NEWS
author ballarin
Wed Jul 19 19:25:58 2006 +0200 (2006-07-19)
changeset 20168 ed7bced29e1b
parent 20136 8e92a8f9720b
child 20169 52173f7687fd
permissions -rw-r--r--
Reimplemented algebra method; now controlled by attribute.
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** General ***
     8 
     9 * Theory syntax: the header format ``theory A = B + C:'' has been
    10 discontinued in favour of ``theory A imports B C begin''.  Use isatool
    11 fixheaders to convert existing theory files.  INCOMPATIBILITY.
    12 
    13 * Theory syntax: the old non-Isar theory file format has been
    14 discontinued altogether.  Note that ML proof scripts may still be used
    15 with Isar theories; migration is usually quite simple with the ML
    16 function use_legacy_bindings.  INCOMPATIBILITY.
    17 
    18 * Theory syntax: some popular names (e.g. "class", "if") are now
    19 keywords.  INCOMPATIBILITY, use double quotes.
    20 
    21 * Legacy goal package: reduced interface to the bare minimum required
    22 to keep existing proof scripts running.  Most other user-level
    23 functions are now part of the OldGoals structure, which is *not* open
    24 by default (consider isatool expandshort before open OldGoals).
    25 Removed top_sg, prin, printyp, pprint_term/typ altogether, because
    26 these tend to cause confusion about the actual goal (!) context being
    27 used here, which is not necessarily the same as the_context().
    28 
    29 * Command 'find_theorems': support "*" wildcard in "name:" criterion.
    30 
    31 
    32 *** Document preparation ***
    33 
    34 * Added antiquotations @{ML_type text} and @{ML_struct text} which
    35 check the given source text as ML type/structure, printing verbatim.
    36 
    37 
    38 *** Pure ***
    39 
    40 * Command 'no_translations' removes translation rules from theory
    41 syntax.
    42 
    43 * Overloaded definitions are now actually checked for acyclic
    44 dependencies.  The overloading scheme is slightly more general than
    45 that of Haskell98, although Isabelle does not demand an exact
    46 correspondence to type class and instance declarations.
    47 INCOMPATIBILITY, use ``defs (unchecked overloaded)'' to admit more
    48 exotic versions of overloading -- at the discretion of the user!
    49 
    50 Polymorphic constants are represented via type arguments, i.e. the
    51 instantiation that matches an instance against the most general
    52 declaration given in the signature.  For example, with the declaration
    53 c :: 'a => 'a => 'a, an instance c :: nat => nat => nat is represented
    54 as c(nat).  Overloading is essentially simultaneous structural
    55 recursion over such type arguments.  Incomplete specification patterns
    56 impose global constraints on all occurrences, e.g. c('a * 'a) on the
    57 LHS means that more general c('a * 'b) will be disallowed on any RHS.
    58 Command 'print_theory' outputs the normalized system of recursive
    59 equations, see section "definitions".
    60 
    61 * Isar: improper proof element 'guess' is like 'obtain', but derives
    62 the obtained context from the course of reasoning!  For example:
    63 
    64   assume "EX x y. A x & B y"   -- "any previous fact"
    65   then guess x and y by clarify
    66 
    67 This technique is potentially adventurous, depending on the facts and
    68 proof tools being involved here.
    69 
    70 * Isar: known facts from the proof context may be specified as literal
    71 propositions, using ASCII back-quote syntax.  This works wherever
    72 named facts used to be allowed so far, in proof commands, proof
    73 methods, attributes etc.  Literal facts are retrieved from the context
    74 according to unification of type and term parameters.  For example,
    75 provided that "A" and "A ==> B" and "!!x. P x ==> Q x" are known
    76 theorems in the current context, then these are valid literal facts:
    77 `A` and `A ==> B` and `!!x. P x ==> Q x" as well as `P a ==> Q a` etc.
    78 
    79 There is also a proof method "fact" which does the same composition
    80 for explicit goal states, e.g. the following proof texts coincide with
    81 certain special cases of literal facts:
    82 
    83   have "A" by fact                 ==  note `A`
    84   have "A ==> B" by fact           ==  note `A ==> B`
    85   have "!!x. P x ==> Q x" by fact  ==  note `!!x. P x ==> Q x`
    86   have "P a ==> Q a" by fact       ==  note `P a ==> Q a`
    87 
    88 * Isar: ":" (colon) is no longer a symbolic identifier character in
    89 outer syntax.  Thus symbolic identifiers may be used without
    90 additional white space in declarations like this: ``assume *: A''.
    91 
    92 * Isar: 'print_facts' prints all local facts of the current context,
    93 both named and unnamed ones.
    94 
    95 * Isar: 'def' now admits simultaneous definitions, e.g.:
    96 
    97   def x == "t" and y == "u"
    98 
    99 * Isar: added command 'unfolding', which is structurally similar to
   100 'using', but affects both the goal state and facts by unfolding given
   101 rewrite rules.  Thus many occurrences of the 'unfold' method or
   102 'unfolded' attribute may be replaced by first-class proof text.
   103 
   104 * Isar: methods 'unfold' / 'fold', attributes 'unfolded' / 'folded',
   105 and command 'unfolding' now all support object-level equalities
   106 (potentially conditional).  The underlying notion of rewrite rule is
   107 analogous to the 'rule_format' attribute, but *not* that of the
   108 Simplifier (which is usually more generous).
   109 
   110 * Isar: the goal restriction operator [N] (default N = 1) evaluates a
   111 method expression within a sandbox consisting of the first N
   112 sub-goals, which need to exist.  For example, ``simp_all [3]''
   113 simplifies the first three sub-goals, while (rule foo, simp_all)[]
   114 simplifies all new goals that emerge from applying rule foo to the
   115 originally first one.
   116 
   117 * Isar: schematic goals are no longer restricted to higher-order
   118 patterns; e.g. ``lemma "?P(?x)" by (rule TrueI)'' now works as
   119 expected.
   120 
   121 * Isar: the conclusion of a long theorem statement is now either
   122 'shows' (a simultaneous conjunction, as before), or 'obtains'
   123 (essentially a disjunction of cases with local parameters and
   124 assumptions).  The latter allows to express general elimination rules
   125 adequately; in this notation common elimination rules look like this:
   126 
   127   lemma exE:    -- "EX x. P x ==> (!!x. P x ==> thesis) ==> thesis"
   128     assumes "EX x. P x"
   129     obtains x where "P x"
   130 
   131   lemma conjE:  -- "A & B ==> (A ==> B ==> thesis) ==> thesis"
   132     assumes "A & B"
   133     obtains A and B
   134 
   135   lemma disjE:  -- "A | B ==> (A ==> thesis) ==> (B ==> thesis) ==> thesis"
   136     assumes "A | B"
   137     obtains
   138       A
   139     | B
   140 
   141 The subsequent classical rules even refer to the formal "thesis"
   142 explicitly:
   143 
   144   lemma classical:     -- "(~ thesis ==> thesis) ==> thesis"
   145     obtains "~ thesis"
   146 
   147   lemma Peirce's_Law:  -- "((thesis ==> something) ==> thesis) ==> thesis"
   148     obtains "thesis ==> something"
   149 
   150 The actual proof of an 'obtains' statement is analogous to that of the
   151 Isar proof element 'obtain', only that there may be several cases.
   152 Optional case names may be specified in parentheses; these will be
   153 available both in the present proof and as annotations in the
   154 resulting rule, for later use with the 'cases' method (cf. attribute
   155 case_names).
   156 
   157 * Isar: 'print_statement' prints theorems from the current theory or
   158 proof context in long statement form, according to the syntax of a
   159 top-level lemma.
   160 
   161 * Isar: 'obtain' takes an optional case name for the local context
   162 introduction rule (default "that").
   163 
   164 * Isar: removed obsolete 'concl is' patterns.  INCOMPATIBILITY, use
   165 explicit (is "_ ==> ?foo") in the rare cases where this still happens
   166 to occur.
   167 
   168 * Pure: syntax "CONST name" produces a fully internalized constant
   169 according to the current context.  This is particularly useful for
   170 syntax translations that should refer to internal constant
   171 representations independently of name spaces.
   172 
   173 * Isar/locales: 'const_syntax' provides a robust interface to the
   174 'syntax' primitive that also works in a locale context.  Type
   175 declaration and internal syntactic representation of given constants
   176 retrieved from the context.
   177 
   178 * Isar/locales: new derived specification elements 'axiomatization',
   179 'definition', 'abbreviation', which support type-inference, admit
   180 object-level specifications (equality, equivalence).  See also the
   181 isar-ref manual.  Examples:
   182 
   183   axiomatization
   184     eq  (infix "===" 50)
   185     where eq_refl: "x === x" and eq_subst: "x === y ==> P x ==> P y"
   186 
   187   definition
   188     "f x y = x + y + 1"
   189     "g x = f x x"
   190 
   191   abbreviation
   192     neq  (infix "=!=" 50)
   193     "x =!= y == ~ (x === y)"
   194 
   195 These specifications may be also used in a locale context.  Then the
   196 constants being introduced depend on certain fixed parameters, and the
   197 constant name is qualified by the locale base name.  An internal
   198 abbreviation takes care for convenient input and output, making the
   199 parameters implicit and using the original short name.  See also
   200 HOL/ex/Abstract_NAT.thy for an example of deriving polymorphic
   201 entities from a monomorphic theory.
   202 
   203 Presently, abbreviations are only available 'in' a target locale, but
   204 not inherited by general import expressions.  Also note that
   205 'abbreviation' may be used as a type-safe replacement for 'syntax' +
   206 'translations' in common applications.
   207 
   208 Concrete syntax is attached to specified constants in internal form,
   209 independently of name spaces.  The parse tree representation is
   210 slightly different -- use 'const_syntax' instead of raw 'syntax', and
   211 'translations' with explicit "CONST" markup to accommodate this.
   212 
   213 * Isar/locales: improved parameter handling:
   214 - use of locales "var" and "struct" no longer necessary;
   215 - parameter renamings are no longer required to be injective.
   216   This enables, for example, to define a locale for endomorphisms thus:
   217   locale endom = homom mult mult h.
   218 
   219 * Isar/locales: changed the way locales with predicates are defined.
   220 Instead of accumulating the specification, the imported expression is
   221 now an interpretation.
   222 INCOMPATIBILITY: different normal form of locale expressions.
   223 In particular, in interpretations of locales with predicates,
   224 goals repesenting already interpreted fragments are not removed
   225 automatically.  Use methods `intro_locales' and `unfold_locales'; see below.
   226 
   227 * Isar/locales: new methods `intro_locales' and `unfold_locales' provide
   228 backward reasoning on locales predicates.  The methods are aware of
   229 interpretations and discharge corresponding goals.  `intro_locales' is
   230 less aggressive then `unfold_locales' and does not unfold predicates to
   231 assumptions.
   232 
   233 * Isar/locales: the order in which locale fragments are accumulated
   234 has changed.  This enables to override declarations from fragments
   235 due to interpretations -- for example, unwanted simp rules.
   236 
   237 * Provers/induct: improved internal context management to support
   238 local fixes and defines on-the-fly.  Thus explicit meta-level
   239 connectives !! and ==> are rarely required anymore in inductive goals
   240 (using object-logic connectives for this purpose has been long
   241 obsolete anyway).  The subsequent proof patterns illustrate advanced
   242 techniques of natural induction; general datatypes and inductive sets
   243 work analogously (see also src/HOL/Lambda for realistic examples).
   244 
   245 (1) This is how to ``strengthen'' an inductive goal wrt. certain
   246 parameters:
   247 
   248   lemma
   249     fixes n :: nat and x :: 'a
   250     assumes a: "A n x"
   251     shows "P n x"
   252     using a                     -- {* make induct insert fact a *}
   253   proof (induct n fixing: x)    -- {* generalize goal to "!!x. A n x ==> P n x" *}
   254     case 0
   255     show ?case sorry
   256   next
   257     case (Suc n)
   258     note `!!x. A n x ==> P n x` -- {* induction hypothesis, according to induction rule *}
   259     note `A (Suc n) x`          -- {* induction premise, stemming from fact a *}
   260     show ?case sorry
   261   qed
   262 
   263 (2) This is how to perform induction over ``expressions of a certain
   264 form'', using a locally defined inductive parameter n == "a x"
   265 together with strengthening (the latter is usually required to get
   266 sufficiently flexible induction hypotheses):
   267 
   268   lemma
   269     fixes a :: "'a => nat"
   270     assumes a: "A (a x)"
   271     shows "P (a x)"
   272     using a
   273   proof (induct n == "a x" fixing: x)
   274     ...
   275 
   276 See also HOL/Isar_examples/Puzzle.thy for an application of the this
   277 particular technique.
   278 
   279 (3) This is how to perform existential reasoning ('obtains' or
   280 'obtain') by induction, while avoiding explicit object-logic
   281 encodings:
   282 
   283   lemma
   284     fixes n :: nat
   285     obtains x :: 'a where "P n x" and "Q n x"
   286   proof (induct n fixing: thesis)
   287     case 0
   288     obtain x where "P 0 x" and "Q 0 x" sorry
   289     then show thesis by (rule 0)
   290   next
   291     case (Suc n)
   292     obtain x where "P n x" and "Q n x" by (rule Suc.hyps)
   293     obtain x where "P (Suc n) x" and "Q (Suc n) x" sorry
   294     then show thesis by (rule Suc.prems)
   295   qed
   296 
   297 Here the 'fixing: thesis' specification essentially modifies the scope
   298 of the formal thesis parameter, in order to the get the whole
   299 existence statement through the induction as expected.
   300 
   301 * Provers/induct: mutual induction rules are now specified as a list
   302 of rule sharing the same induction cases.  HOL packages usually
   303 provide foo_bar.inducts for mutually defined items foo and bar
   304 (e.g. inductive sets or datatypes).  INCOMPATIBILITY, users need to
   305 specify mutual induction rules differently, i.e. like this:
   306 
   307   (induct rule: foo_bar.inducts)
   308   (induct set: foo bar)
   309   (induct type: foo bar)
   310 
   311 The ML function ProjectRule.projections turns old-style rules into the
   312 new format.
   313 
   314 * Provers/induct: improved handling of simultaneous goals.  Instead of
   315 introducing object-level conjunction, the statement is now split into
   316 several conclusions, while the corresponding symbolic cases are
   317 nested accordingly.  INCOMPATIBILITY, proofs need to be structured
   318 explicitly.  For example:
   319 
   320   lemma
   321     fixes n :: nat
   322     shows "P n" and "Q n"
   323   proof (induct n)
   324     case 0 case 1
   325     show "P 0" sorry
   326   next
   327     case 0 case 2
   328     show "Q 0" sorry
   329   next
   330     case (Suc n) case 1
   331     note `P n` and `Q n`
   332     show "P (Suc n)" sorry
   333   next
   334     case (Suc n) case 2
   335     note `P n` and `Q n`
   336     show "Q (Suc n)" sorry
   337   qed
   338 
   339 The split into subcases may be deferred as follows -- this is
   340 particularly relevant for goal statements with local premises.
   341 
   342   lemma
   343     fixes n :: nat
   344     shows "A n ==> P n" and "B n ==> Q n"
   345   proof (induct n)
   346     case 0
   347     {
   348       case 1
   349       note `A 0`
   350       show "P 0" sorry
   351     next
   352       case 2
   353       note `B 0`
   354       show "Q 0" sorry
   355     }
   356   next
   357     case (Suc n)
   358     note `A n ==> P n` and `B n ==> Q n`
   359     {
   360       case 1
   361       note `A (Suc n)`
   362       show "P (Suc n)" sorry
   363     next
   364       case 2
   365       note `B (Suc n)`
   366       show "Q (Suc n)" sorry
   367     }
   368   qed
   369 
   370 If simultaneous goals are to be used with mutual rules, the statement
   371 needs to be structured carefully as a two-level conjunction, using
   372 lists of propositions separated by 'and':
   373 
   374   lemma
   375     shows "a : A ==> P1 a"
   376           "a : A ==> P2 a"
   377       and "b : B ==> Q1 b"
   378           "b : B ==> Q2 b"
   379           "b : B ==> Q3 b"
   380   proof (induct set: A B)
   381 
   382 * Provers/induct: support coinduction as well.  See
   383 src/HOL/Library/Coinductive_List.thy for various examples.
   384 
   385 * Simplifier: by default the simplifier trace only shows top level rewrites
   386 now. That is, trace_simp_depth_limit is set to 1 by default. Thus there is
   387 less danger of being flooded by the trace. The trace indicates where parts
   388 have been suppressed.
   389   
   390 * Provers/classical: removed obsolete classical version of elim_format
   391 attribute; classical elim/dest rules are now treated uniformly when
   392 manipulating the claset.
   393 
   394 * Provers/classical: stricter checks to ensure that supplied intro,
   395 dest and elim rules are well-formed; dest and elim rules must have at
   396 least one premise.
   397 
   398 * Provers/classical: attributes dest/elim/intro take an optional
   399 weight argument for the rule (just as the Pure versions).  Weights are
   400 ignored by automated tools, but determine the search order of single
   401 rule steps.
   402 
   403 * Syntax: input syntax now supports dummy variable binding "%_. b",
   404 where the body does not mention the bound variable.  Note that dummy
   405 patterns implicitly depend on their context of bounds, which makes
   406 "{_. _}" match any set comprehension as expected.  Potential
   407 INCOMPATIBILITY -- parse translations need to cope with syntactic
   408 constant "_idtdummy" in the binding position.
   409 
   410 * Syntax: removed obsolete syntactic constant "_K" and its associated
   411 parse translation.  INCOMPATIBILITY -- use dummy abstraction instead,
   412 for example "A -> B" => "Pi A (%_. B)".
   413 
   414 
   415 *** HOL ***
   416 
   417 * New top level command 'normal_form' computes the normal form of a term
   418 that may contain free variables. For example 'normal_form "rev[a,b,c]"'
   419 prints '[b,c,a]'. This command is suitable for heavy-duty computations
   420 because the functions are compiled to ML first.
   421 INCOMPATIBILITY: new keywords 'normal_form' must quoted when used as
   422 an identifier.
   423 
   424 * Alternative iff syntax "A <-> B" for equality on bool (with priority
   425 25 like -->); output depends on the "iff" print_mode, the default is
   426 "A = B" (with priority 50).
   427 
   428 * Renamed constants in HOL.thy and Orderings.thy:
   429     op +   ~> HOL.plus
   430     op -   ~> HOL.minus
   431     uminus ~> HOL.uminus
   432     op *   ~> HOL.times
   433     op <   ~> Orderings.less
   434     op <=  ~> Orderings.less_eq
   435 
   436 Adaptions may be required in the following cases:
   437 
   438 a) User-defined constants using any of the names "plus", "minus", "times",
   439 "less" or "less_eq". The standard syntax translations for "+", "-" and "*"
   440 may go wrong.
   441 INCOMPATIBILITY: use more specific names.
   442 
   443 b) Variables named "plus", "minus", "times", "less", "less_eq"
   444 INCOMPATIBILITY: use more specific names.
   445 
   446 c) Permutative equations (e.g. "a + b = b + a")
   447 Since the change of names also changes the order of terms, permutative
   448 rewrite rules may get applied in a different order. Experience shows that
   449 this is rarely the case (only two adaptions in the whole Isabelle
   450 distribution).
   451 INCOMPATIBILITY: rewrite proofs
   452 
   453 d) ML code directly refering to constant names
   454 This in general only affects hand-written proof tactics, simprocs and so on.
   455 INCOMPATIBILITY: grep your sourcecode and replace names.
   456 
   457 * "LEAST x:A. P" expands to "LEAST x. x:A & P" (input only).
   458 
   459 * The old set interval syntax "{m..n(}" (and relatives) has been removed.
   460   Use "{m..<n}" (and relatives) instead.
   461 
   462 * In the context of the assumption "~(s = t)" the Simplifier rewrites
   463 "t = s" to False (by simproc "neq_simproc").  For backward
   464 compatibility this can be disabled by ML "reset use_neq_simproc".
   465 
   466 * "m dvd n" where m and n are numbers is evaluated to True/False by simp.
   467 
   468 * Theorem Cons_eq_map_conv no longer has attribute `simp'.
   469 
   470 * Theorem setsum_mult renamed to setsum_right_distrib.
   471 
   472 * Prefer ex1I over ex_ex1I in single-step reasoning, e.g. by the
   473 'rule' method.
   474 
   475 * Tactics 'sat' and 'satx' reimplemented, several improvements: goals
   476 no longer need to be stated as "<prems> ==> False", equivalences (i.e.
   477 "=" on type bool) are handled, variable names of the form "lit_<n>"
   478 are no longer reserved, significant speedup.
   479 
   480 * Tactics 'sat' and 'satx' can now replay MiniSat proof traces.  zChaff is
   481 still supported as well.
   482 
   483 * inductive and datatype: provide projections of mutual rules, bundled
   484 as foo_bar.inducts;
   485 
   486 * Library: theory Accessible_Part has been move to main HOL.
   487 
   488 * Library: added theory Coinductive_List of potentially infinite lists
   489 as greatest fixed-point.
   490 
   491 * Library: added theory AssocList which implements (finite) maps as
   492 association lists.
   493 
   494 * New proof method "evaluation" for efficiently solving a goal
   495   (i.e. a boolean expression) by compiling it to ML. The goal is
   496   "proved" (via the oracle "Evaluation") if it evaluates to True.
   497 
   498 * Support for hex (0x20) and binary (0b1001) numerals. 
   499 
   500 *** HOL-Complex ***
   501 
   502 * Theory Real: new method ferrack implements quantifier elimination
   503 for linear arithmetic over the reals. The quantifier elimination
   504 feature is used only for decision, for compatibility with arith. This
   505 means a goal is either solved or left unchanged, no simplification.
   506 
   507 
   508 *** ML ***
   509 
   510 * Pure/library:
   511 
   512   val burrow: ('a list -> 'b list) -> 'a list list -> 'b list list
   513   val fold_burrow: ('a list -> 'c -> 'b list * 'd) -> 'a list list -> 'c -> 'b list list * 'd
   514 
   515 The semantics of "burrow" is: "take a function with *simulatanously*
   516 transforms a list of value, and apply it *simulatanously* to a list of
   517 list of values of the appropriate type". Confer this with "map" which
   518 would *not* apply its argument function simulatanously but in
   519 sequence. "fold_burrow" has an additional context.
   520 
   521 Both actually avoid the usage of "unflat" since they hide away
   522 "unflat" from the user.
   523 
   524 * Pure/library: functions map2 and fold2 with curried syntax for
   525 simultanous mapping and folding:
   526 
   527     val map2: ('a -> 'b -> 'c) -> 'a list -> 'b list -> 'c list
   528     val fold2: ('a -> 'b -> 'c -> 'c) -> 'a list -> 'b list -> 'c -> 'c
   529 
   530 * Pure/library: indexed lists - some functions in the Isabelle library
   531 treating lists over 'a as finite mappings from [0...n] to 'a have been
   532 given more convenient names and signatures reminiscent of similar
   533 functions for alists, tables, etc:
   534 
   535   val nth: 'a list -> int -> 'a 
   536   val nth_update: int * 'a -> 'a list -> 'a list
   537   val nth_map: int -> ('a -> 'a) -> 'a list -> 'a list
   538   val fold_index: (int * 'a -> 'b -> 'b) -> 'a list -> 'b -> 'b
   539 
   540 Note that fold_index starts counting at index 0, not 1 like foldln
   541 used to.
   542 
   543 * Pure/library: general ``divide_and_conquer'' combinator on lists.
   544 
   545 * Pure/General/name_mangler.ML provides a functor for generic name
   546 mangling (bijective mapping from any expression values to strings).
   547 
   548 * Pure/General/rat.ML implements rational numbers.
   549 
   550 * Pure/General/table.ML: the join operations now works via exceptions
   551 DUP/SAME instead of type option.  This is simpler in simple cases, and
   552 admits slightly more efficient complex applications.
   553 
   554 * Pure: datatype Context.generic joins theory/Proof.context and
   555 provides some facilities for code that works in either kind of
   556 context, notably GenericDataFun for uniform theory and proof data.
   557 
   558 * Pure: 'advanced' translation functions (parse_translation etc.) now
   559 use Context.generic instead of just theory.
   560 
   561 * Pure: simplified internal attribute type, which is now always
   562 Context.generic * thm -> Context.generic * thm.  Global (theory)
   563 vs. local (Proof.context) attributes have been discontinued, while
   564 minimizing code duplication.  Thm.rule_attribute and
   565 Thm.declaration_attribute build canonical attributes; see also
   566 structure Context for further operations on Context.generic, notably
   567 GenericDataFun.  INCOMPATIBILITY, need to adapt attribute type
   568 declarations and definitions.
   569 
   570 * Pure/kernel: consts certification ignores sort constraints given in
   571 signature declarations.  (This information is not relevant to the
   572 logic, but only for type inference.)  IMPORTANT INTERNAL CHANGE.
   573 
   574 * Pure: axiomatic type classes are now purely definitional, with
   575 explicit proofs of class axioms and super class relations performed
   576 internally.  See Pure/axclass.ML for the main internal interfaces --
   577 notably AxClass.define_class supercedes AxClass.add_axclass, and
   578 AxClass.axiomatize_class/classrel/arity supercede
   579 Sign.add_classes/classrel/arities.
   580 
   581 * Pure/Isar: Args/Attrib parsers operate on Context.generic --
   582 global/local versions on theory vs. Proof.context have been
   583 discontinued; Attrib.syntax and Method.syntax have been adapted
   584 accordingly.  INCOMPATIBILITY, need to adapt parser expressions for
   585 attributes, methods, etc.
   586 
   587 * Pure: several functions of signature "... -> theory -> theory * ..."
   588 have been reoriented to "... -> theory -> ... * theory" in order to
   589 allow natural usage in combination with the ||>, ||>>, |-> and
   590 fold_map combinators.
   591 
   592 * Pure: primitive rule lift_rule now takes goal cterm instead of an
   593 actual goal state (thm).  Use Thm.lift_rule (Thm.cprem_of st i) to
   594 achieve the old behaviour.
   595 
   596 * Pure: the "Goal" constant is now called "prop", supporting a
   597 slightly more general idea of ``protecting'' meta-level rule
   598 statements.
   599 
   600 * Pure: Logic.(un)varify only works in a global context, which is now
   601 enforced instead of silently assumed.  INCOMPATIBILITY, may use
   602 Logic.legacy_(un)varify as temporary workaround.
   603 
   604 * Pure: structure Name provides scalable operations for generating
   605 internal variable names, notably Name.variants etc.  This replaces
   606 some popular functions from term.ML:
   607 
   608   Term.variant		->  Name.variant
   609   Term.variantlist	->  Name.variant_list  (*canonical argument order*)
   610   Term.invent_names	->  Name.invent_list
   611 
   612 Note that low-level renaming rarely occurs in new code -- operations
   613 from structure Variable are used instead (see below).
   614 
   615 * Pure: structure Variable provides fundamental operations for proper
   616 treatment of fixed/schematic variables in a context.  For example,
   617 Variable.import introduces fixes for schematics of given facts and
   618 Variable.export reverses the effect (up to renaming) -- this replaces
   619 various freeze_thaw operations.
   620 
   621 * Pure: structure Goal provides simple interfaces for
   622 init/conclude/finish and tactical prove operations (replacing former
   623 Tactic.prove).  Goal.prove is the canonical way to prove results
   624 within a given context; Goal.prove_global is a degraded version for
   625 theory level goals, including a global Drule.standard.  Note that
   626 OldGoals.prove_goalw_cterm has long been obsolete, since it is
   627 ill-behaved in a local proof context (e.g. with local fixes/assumes or
   628 in a locale context).
   629 
   630 * Isar: simplified treatment of user-level errors, using exception
   631 ERROR of string uniformly.  Function error now merely raises ERROR,
   632 without any side effect on output channels.  The Isar toplevel takes
   633 care of proper display of ERROR exceptions.  ML code may use plain
   634 handle/can/try; cat_error may be used to concatenate errors like this:
   635 
   636   ... handle ERROR msg => cat_error msg "..."
   637 
   638 Toplevel ML code (run directly or through the Isar toplevel) may be
   639 embedded into the Isar toplevel with exception display/debug like
   640 this:
   641 
   642   Isar.toplevel (fn () => ...)
   643 
   644 INCOMPATIBILITY, removed special transform_error facilities, removed
   645 obsolete variants of user-level exceptions (ERROR_MESSAGE,
   646 Context.PROOF, ProofContext.CONTEXT, Proof.STATE, ProofHistory.FAIL)
   647 -- use plain ERROR instead.
   648 
   649 * Isar: theory setup now has type (theory -> theory), instead of a
   650 list.  INCOMPATIBILITY, may use #> to compose setup functions.
   651 
   652 * Isar: installed ML toplevel pretty printer for type Proof.context,
   653 subject to ProofContext.debug/verbose flags.
   654 
   655 * Isar: Toplevel.theory_to_proof admits transactions that modify the
   656 theory before entering a proof state.  Transactions now always see a
   657 quasi-functional intermediate checkpoint, both in interactive and
   658 batch mode.
   659 
   660 * Simplifier: the simpset of a running simplification process now
   661 contains a proof context (cf. Simplifier.the_context), which is the
   662 very context that the initial simpset has been retrieved from (by
   663 simpset_of/local_simpset_of).  Consequently, all plug-in components
   664 (solver, looper etc.) may depend on arbitrary proof data.
   665 
   666 * Simplifier.inherit_context inherits the proof context (plus the
   667 local bounds) of the current simplification process; any simproc
   668 etc. that calls the Simplifier recursively should do this!  Removed
   669 former Simplifier.inherit_bounds, which is already included here --
   670 INCOMPATIBILITY.  Tools based on low-level rewriting may even have to
   671 specify an explicit context using Simplifier.context/theory_context.
   672 
   673 * Simplifier/Classical Reasoner: more abstract interfaces
   674 change_simpset/claset for modifying the simpset/claset reference of a
   675 theory; raw versions simpset/claset_ref etc. have been discontinued --
   676 INCOMPATIBILITY.
   677 
   678 * Provers: more generic wrt. syntax of object-logics, avoid hardwired
   679 "Trueprop" etc.
   680 
   681 
   682 
   683 New in Isabelle2005 (October 2005)
   684 ----------------------------------
   685 
   686 *** General ***
   687 
   688 * Theory headers: the new header syntax for Isar theories is
   689 
   690   theory <name>
   691   imports <theory1> ... <theoryN>
   692   uses <file1> ... <fileM>
   693   begin
   694 
   695 where the 'uses' part is optional.  The previous syntax
   696 
   697   theory <name> = <theory1> + ... + <theoryN>:
   698 
   699 will disappear in the next release.  Use isatool fixheaders to convert
   700 existing theory files.  Note that there is no change in ancient
   701 non-Isar theories now, but these will disappear soon.
   702 
   703 * Theory loader: parent theories can now also be referred to via
   704 relative and absolute paths.
   705 
   706 * Command 'find_theorems' searches for a list of criteria instead of a
   707 list of constants. Known criteria are: intro, elim, dest, name:string,
   708 simp:term, and any term. Criteria can be preceded by '-' to select
   709 theorems that do not match. Intro, elim, dest select theorems that
   710 match the current goal, name:s selects theorems whose fully qualified
   711 name contain s, and simp:term selects all simplification rules whose
   712 lhs match term.  Any other term is interpreted as pattern and selects
   713 all theorems matching the pattern. Available in ProofGeneral under
   714 'ProofGeneral -> Find Theorems' or C-c C-f.  Example:
   715 
   716   C-c C-f (100) "(_::nat) + _ + _" intro -name: "HOL."
   717 
   718 prints the last 100 theorems matching the pattern "(_::nat) + _ + _",
   719 matching the current goal as introduction rule and not having "HOL."
   720 in their name (i.e. not being defined in theory HOL).
   721 
   722 * Command 'thms_containing' has been discontinued in favour of
   723 'find_theorems'; INCOMPATIBILITY.
   724 
   725 * Communication with Proof General is now 8bit clean, which means that
   726 Unicode text in UTF-8 encoding may be used within theory texts (both
   727 formal and informal parts).  Cf. option -U of the Isabelle Proof
   728 General interface.  Here are some simple examples (cf. src/HOL/ex):
   729 
   730   http://isabelle.in.tum.de/library/HOL/ex/Hebrew.html
   731   http://isabelle.in.tum.de/library/HOL/ex/Chinese.html
   732 
   733 * Improved efficiency of the Simplifier and, to a lesser degree, the
   734 Classical Reasoner.  Typical big applications run around 2 times
   735 faster.
   736 
   737 
   738 *** Document preparation ***
   739 
   740 * Commands 'display_drafts' and 'print_drafts' perform simple output
   741 of raw sources.  Only those symbols that do not require additional
   742 LaTeX packages (depending on comments in isabellesym.sty) are
   743 displayed properly, everything else is left verbatim.  isatool display
   744 and isatool print are used as front ends (these are subject to the
   745 DVI/PDF_VIEWER and PRINT_COMMAND settings, respectively).
   746 
   747 * Command tags control specific markup of certain regions of text,
   748 notably folding and hiding.  Predefined tags include "theory" (for
   749 theory begin and end), "proof" for proof commands, and "ML" for
   750 commands involving ML code; the additional tags "visible" and
   751 "invisible" are unused by default.  Users may give explicit tag
   752 specifications in the text, e.g. ''by %invisible (auto)''.  The
   753 interpretation of tags is determined by the LaTeX job during document
   754 preparation: see option -V of isatool usedir, or options -n and -t of
   755 isatool document, or even the LaTeX macros \isakeeptag, \isafoldtag,
   756 \isadroptag.
   757 
   758 Several document versions may be produced at the same time via isatool
   759 usedir (the generated index.html will link all of them).  Typical
   760 specifications include ''-V document=theory,proof,ML'' to present
   761 theory/proof/ML parts faithfully, ''-V outline=/proof,/ML'' to fold
   762 proof and ML commands, and ''-V mutilated=-theory,-proof,-ML'' to omit
   763 these parts without any formal replacement text.  The Isabelle site
   764 default settings produce ''document'' and ''outline'' versions as
   765 specified above.
   766 
   767 * Several new antiquotations:
   768 
   769   @{term_type term} prints a term with its type annotated;
   770 
   771   @{typeof term} prints the type of a term;
   772 
   773   @{const const} is the same as @{term const}, but checks that the
   774   argument is a known logical constant;
   775 
   776   @{term_style style term} and @{thm_style style thm} print a term or
   777   theorem applying a "style" to it
   778 
   779   @{ML text}
   780 
   781 Predefined styles are 'lhs' and 'rhs' printing the lhs/rhs of
   782 definitions, equations, inequations etc., 'concl' printing only the
   783 conclusion of a meta-logical statement theorem, and 'prem1' .. 'prem19'
   784 to print the specified premise.  TermStyle.add_style provides an ML
   785 interface for introducing further styles.  See also the "LaTeX Sugar"
   786 document practical applications.  The ML antiquotation prints
   787 type-checked ML expressions verbatim.
   788 
   789 * Markup commands 'chapter', 'section', 'subsection', 'subsubsection',
   790 and 'text' support optional locale specification '(in loc)', which
   791 specifies the default context for interpreting antiquotations.  For
   792 example: 'text (in lattice) {* @{thm inf_assoc}*}'.
   793 
   794 * Option 'locale=NAME' of antiquotations specifies an alternative
   795 context interpreting the subsequent argument.  For example: @{thm
   796 [locale=lattice] inf_assoc}.
   797 
   798 * Proper output of proof terms (@{prf ...} and @{full_prf ...}) within
   799 a proof context.
   800 
   801 * Proper output of antiquotations for theory commands involving a
   802 proof context (such as 'locale' or 'theorem (in loc) ...').
   803 
   804 * Delimiters of outer tokens (string etc.) now produce separate LaTeX
   805 macros (\isachardoublequoteopen, isachardoublequoteclose etc.).
   806 
   807 * isatool usedir: new option -C (default true) controls whether option
   808 -D should include a copy of the original document directory; -C false
   809 prevents unwanted effects such as copying of administrative CVS data.
   810 
   811 
   812 *** Pure ***
   813 
   814 * Considerably improved version of 'constdefs' command.  Now performs
   815 automatic type-inference of declared constants; additional support for
   816 local structure declarations (cf. locales and HOL records), see also
   817 isar-ref manual.  Potential INCOMPATIBILITY: need to observe strictly
   818 sequential dependencies of definitions within a single 'constdefs'
   819 section; moreover, the declared name needs to be an identifier.  If
   820 all fails, consider to fall back on 'consts' and 'defs' separately.
   821 
   822 * Improved indexed syntax and implicit structures.  First of all,
   823 indexed syntax provides a notational device for subscripted
   824 application, using the new syntax \<^bsub>term\<^esub> for arbitrary
   825 expressions.  Secondly, in a local context with structure
   826 declarations, number indexes \<^sub>n or the empty index (default
   827 number 1) refer to a certain fixed variable implicitly; option
   828 show_structs controls printing of implicit structures.  Typical
   829 applications of these concepts involve record types and locales.
   830 
   831 * New command 'no_syntax' removes grammar declarations (and
   832 translations) resulting from the given syntax specification, which is
   833 interpreted in the same manner as for the 'syntax' command.
   834 
   835 * 'Advanced' translation functions (parse_translation etc.) may depend
   836 on the signature of the theory context being presently used for
   837 parsing/printing, see also isar-ref manual.
   838 
   839 * Improved 'oracle' command provides a type-safe interface to turn an
   840 ML expression of type theory -> T -> term into a primitive rule of
   841 type theory -> T -> thm (i.e. the functionality of Thm.invoke_oracle
   842 is already included here); see also FOL/ex/IffExample.thy;
   843 INCOMPATIBILITY.
   844 
   845 * axclass: name space prefix for class "c" is now "c_class" (was "c"
   846 before); "cI" is no longer bound, use "c.intro" instead.
   847 INCOMPATIBILITY.  This change avoids clashes of fact bindings for
   848 axclasses vs. locales.
   849 
   850 * Improved internal renaming of symbolic identifiers -- attach primes
   851 instead of base 26 numbers.
   852 
   853 * New flag show_question_marks controls printing of leading question
   854 marks in schematic variable names.
   855 
   856 * In schematic variable names, *any* symbol following \<^isub> or
   857 \<^isup> is now treated as part of the base name.  For example, the
   858 following works without printing of awkward ".0" indexes:
   859 
   860   lemma "x\<^isub>1 = x\<^isub>2 ==> x\<^isub>2 = x\<^isub>1"
   861     by simp
   862 
   863 * Inner syntax includes (*(*nested*) comments*).
   864 
   865 * Pretty printer now supports unbreakable blocks, specified in mixfix
   866 annotations as "(00...)".
   867 
   868 * Clear separation of logical types and nonterminals, where the latter
   869 may only occur in 'syntax' specifications or type abbreviations.
   870 Before that distinction was only partially implemented via type class
   871 "logic" vs. "{}".  Potential INCOMPATIBILITY in rare cases of improper
   872 use of 'types'/'consts' instead of 'nonterminals'/'syntax'.  Some very
   873 exotic syntax specifications may require further adaption
   874 (e.g. Cube/Cube.thy).
   875 
   876 * Removed obsolete type class "logic", use the top sort {} instead.
   877 Note that non-logical types should be declared as 'nonterminals'
   878 rather than 'types'.  INCOMPATIBILITY for new object-logic
   879 specifications.
   880 
   881 * Attributes 'induct' and 'cases': type or set names may now be
   882 locally fixed variables as well.
   883 
   884 * Simplifier: can now control the depth to which conditional rewriting
   885 is traced via the PG menu Isabelle -> Settings -> Trace Simp Depth
   886 Limit.
   887 
   888 * Simplifier: simplification procedures may now take the current
   889 simpset into account (cf. Simplifier.simproc(_i) / mk_simproc
   890 interface), which is very useful for calling the Simplifier
   891 recursively.  Minor INCOMPATIBILITY: the 'prems' argument of simprocs
   892 is gone -- use prems_of_ss on the simpset instead.  Moreover, the
   893 low-level mk_simproc no longer applies Logic.varify internally, to
   894 allow for use in a context of fixed variables.
   895 
   896 * thin_tac now works even if the assumption being deleted contains !!
   897 or ==>.  More generally, erule now works even if the major premise of
   898 the elimination rule contains !! or ==>.
   899 
   900 * Method 'rules' has been renamed to 'iprover'. INCOMPATIBILITY.
   901 
   902 * Reorganized bootstrapping of the Pure theories; CPure is now derived
   903 from Pure, which contains all common declarations already.  Both
   904 theories are defined via plain Isabelle/Isar .thy files.
   905 INCOMPATIBILITY: elements of CPure (such as the CPure.intro /
   906 CPure.elim / CPure.dest attributes) now appear in the Pure name space;
   907 use isatool fixcpure to adapt your theory and ML sources.
   908 
   909 * New syntax 'name(i-j, i-, i, ...)' for referring to specific
   910 selections of theorems in named facts via index ranges.
   911 
   912 * 'print_theorems': in theory mode, really print the difference
   913 wrt. the last state (works for interactive theory development only),
   914 in proof mode print all local facts (cf. 'print_facts');
   915 
   916 * 'hide': option '(open)' hides only base names.
   917 
   918 * More efficient treatment of intermediate checkpoints in interactive
   919 theory development.
   920 
   921 * Code generator is now invoked via code_module (incremental code
   922 generation) and code_library (modular code generation, ML structures
   923 for each theory).  INCOMPATIBILITY: new keywords 'file' and 'contains'
   924 must be quoted when used as identifiers.
   925 
   926 * New 'value' command for reading, evaluating and printing terms using
   927 the code generator.  INCOMPATIBILITY: command keyword 'value' must be
   928 quoted when used as identifier.
   929 
   930 
   931 *** Locales ***
   932 
   933 * New commands for the interpretation of locale expressions in
   934 theories (1), locales (2) and proof contexts (3).  These generate
   935 proof obligations from the expression specification.  After the
   936 obligations have been discharged, theorems of the expression are added
   937 to the theory, target locale or proof context.  The synopsis of the
   938 commands is a follows:
   939 
   940   (1) interpretation expr inst
   941   (2) interpretation target < expr
   942   (3) interpret expr inst
   943 
   944 Interpretation in theories and proof contexts require a parameter
   945 instantiation of terms from the current context.  This is applied to
   946 specifications and theorems of the interpreted expression.
   947 Interpretation in locales only permits parameter renaming through the
   948 locale expression.  Interpretation is smart in that interpretations
   949 that are active already do not occur in proof obligations, neither are
   950 instantiated theorems stored in duplicate.  Use 'print_interps' to
   951 inspect active interpretations of a particular locale.  For details,
   952 see the Isar Reference manual.  Examples can be found in
   953 HOL/Finite_Set.thy and HOL/Algebra/UnivPoly.thy.
   954 
   955 INCOMPATIBILITY: former 'instantiate' has been withdrawn, use
   956 'interpret' instead.
   957 
   958 * New context element 'constrains' for adding type constraints to
   959 parameters.
   960 
   961 * Context expressions: renaming of parameters with syntax
   962 redeclaration.
   963 
   964 * Locale declaration: 'includes' disallowed.
   965 
   966 * Proper static binding of attribute syntax -- i.e. types / terms /
   967 facts mentioned as arguments are always those of the locale definition
   968 context, independently of the context of later invocations.  Moreover,
   969 locale operations (renaming and type / term instantiation) are applied
   970 to attribute arguments as expected.
   971 
   972 INCOMPATIBILITY of the ML interface: always pass Attrib.src instead of
   973 actual attributes; rare situations may require Attrib.attribute to
   974 embed those attributes into Attrib.src that lack concrete syntax.
   975 Attribute implementations need to cooperate properly with the static
   976 binding mechanism.  Basic parsers Args.XXX_typ/term/prop and
   977 Attrib.XXX_thm etc. already do the right thing without further
   978 intervention.  Only unusual applications -- such as "where" or "of"
   979 (cf. src/Pure/Isar/attrib.ML), which process arguments depending both
   980 on the context and the facts involved -- may have to assign parsed
   981 values to argument tokens explicitly.
   982 
   983 * Changed parameter management in theorem generation for long goal
   984 statements with 'includes'.  INCOMPATIBILITY: produces a different
   985 theorem statement in rare situations.
   986 
   987 * Locale inspection command 'print_locale' omits notes elements.  Use
   988 'print_locale!' to have them included in the output.
   989 
   990 
   991 *** Provers ***
   992 
   993 * Provers/hypsubst.ML: improved version of the subst method, for
   994 single-step rewriting: it now works in bound variable contexts. New is
   995 'subst (asm)', for rewriting an assumption.  INCOMPATIBILITY: may
   996 rewrite a different subterm than the original subst method, which is
   997 still available as 'simplesubst'.
   998 
   999 * Provers/quasi.ML: new transitivity reasoners for transitivity only
  1000 and quasi orders.
  1001 
  1002 * Provers/trancl.ML: new transitivity reasoner for transitive and
  1003 reflexive-transitive closure of relations.
  1004 
  1005 * Provers/blast.ML: new reference depth_limit to make blast's depth
  1006 limit (previously hard-coded with a value of 20) user-definable.
  1007 
  1008 * Provers/simplifier.ML has been moved to Pure, where Simplifier.setup
  1009 is peformed already.  Object-logics merely need to finish their
  1010 initial simpset configuration as before.  INCOMPATIBILITY.
  1011 
  1012 
  1013 *** HOL ***
  1014 
  1015 * Symbolic syntax of Hilbert Choice Operator is now as follows:
  1016 
  1017   syntax (epsilon)
  1018     "_Eps" :: "[pttrn, bool] => 'a"    ("(3\<some>_./ _)" [0, 10] 10)
  1019 
  1020 The symbol \<some> is displayed as the alternative epsilon of LaTeX
  1021 and x-symbol; use option '-m epsilon' to get it actually printed.
  1022 Moreover, the mathematically important symbolic identifier \<epsilon>
  1023 becomes available as variable, constant etc.  INCOMPATIBILITY,
  1024 
  1025 * "x > y" abbreviates "y < x" and "x >= y" abbreviates "y <= x".
  1026 Similarly for all quantifiers: "ALL x > y" etc.  The x-symbol for >=
  1027 is \<ge>. New transitivity rules have been added to HOL/Orderings.thy to
  1028 support corresponding Isar calculations.
  1029 
  1030 * "{x:A. P}" abbreviates "{x. x:A & P}", and similarly for "\<in>"
  1031 instead of ":".
  1032 
  1033 * theory SetInterval: changed the syntax for open intervals:
  1034 
  1035   Old       New
  1036   {..n(}    {..<n}
  1037   {)n..}    {n<..}
  1038   {m..n(}   {m..<n}
  1039   {)m..n}   {m<..n}
  1040   {)m..n(}  {m<..<n}
  1041 
  1042 The old syntax is still supported but will disappear in the next
  1043 release.  For conversion use the following Emacs search and replace
  1044 patterns (these are not perfect but work quite well):
  1045 
  1046   {)\([^\.]*\)\.\.  ->  {\1<\.\.}
  1047   \.\.\([^(}]*\)(}  ->  \.\.<\1}
  1048 
  1049 * Theory Commutative_Ring (in Library): method comm_ring for proving
  1050 equalities in commutative rings; method 'algebra' provides a generic
  1051 interface.
  1052 
  1053 * Theory Finite_Set: changed the syntax for 'setsum', summation over
  1054 finite sets: "setsum (%x. e) A", which used to be "\<Sum>x:A. e", is
  1055 now either "SUM x:A. e" or "\<Sum>x \<in> A. e". The bound variable can
  1056 be a tuple pattern.
  1057 
  1058 Some new syntax forms are available:
  1059 
  1060   "\<Sum>x | P. e"      for     "setsum (%x. e) {x. P}"
  1061   "\<Sum>x = a..b. e"   for     "setsum (%x. e) {a..b}"
  1062   "\<Sum>x = a..<b. e"  for     "setsum (%x. e) {a..<b}"
  1063   "\<Sum>x < k. e"      for     "setsum (%x. e) {..<k}"
  1064 
  1065 The latter form "\<Sum>x < k. e" used to be based on a separate
  1066 function "Summation", which has been discontinued.
  1067 
  1068 * theory Finite_Set: in structured induction proofs, the insert case
  1069 is now 'case (insert x F)' instead of the old counterintuitive 'case
  1070 (insert F x)'.
  1071 
  1072 * The 'refute' command has been extended to support a much larger
  1073 fragment of HOL, including axiomatic type classes, constdefs and
  1074 typedefs, inductive datatypes and recursion.
  1075 
  1076 * New tactics 'sat' and 'satx' to prove propositional tautologies.
  1077 Requires zChaff with proof generation to be installed.  See
  1078 HOL/ex/SAT_Examples.thy for examples.
  1079 
  1080 * Datatype induction via method 'induct' now preserves the name of the
  1081 induction variable. For example, when proving P(xs::'a list) by
  1082 induction on xs, the induction step is now P(xs) ==> P(a#xs) rather
  1083 than P(list) ==> P(a#list) as previously.  Potential INCOMPATIBILITY
  1084 in unstructured proof scripts.
  1085 
  1086 * Reworked implementation of records.  Improved scalability for
  1087 records with many fields, avoiding performance problems for type
  1088 inference. Records are no longer composed of nested field types, but
  1089 of nested extension types. Therefore the record type only grows linear
  1090 in the number of extensions and not in the number of fields.  The
  1091 top-level (users) view on records is preserved.  Potential
  1092 INCOMPATIBILITY only in strange cases, where the theory depends on the
  1093 old record representation. The type generated for a record is called
  1094 <record_name>_ext_type.
  1095 
  1096 Flag record_quick_and_dirty_sensitive can be enabled to skip the
  1097 proofs triggered by a record definition or a simproc (if
  1098 quick_and_dirty is enabled).  Definitions of large records can take
  1099 quite long.
  1100 
  1101 New simproc record_upd_simproc for simplification of multiple record
  1102 updates enabled by default.  Moreover, trivial updates are also
  1103 removed: r(|x := x r|) = r.  INCOMPATIBILITY: old proofs break
  1104 occasionally, since simplification is more powerful by default.
  1105 
  1106 * typedef: proper support for polymorphic sets, which contain extra
  1107 type-variables in the term.
  1108 
  1109 * Simplifier: automatically reasons about transitivity chains
  1110 involving "trancl" (r^+) and "rtrancl" (r^*) by setting up tactics
  1111 provided by Provers/trancl.ML as additional solvers.  INCOMPATIBILITY:
  1112 old proofs break occasionally as simplification may now solve more
  1113 goals than previously.
  1114 
  1115 * Simplifier: converts x <= y into x = y if assumption y <= x is
  1116 present.  Works for all partial orders (class "order"), in particular
  1117 numbers and sets.  For linear orders (e.g. numbers) it treats ~ x < y
  1118 just like y <= x.
  1119 
  1120 * Simplifier: new simproc for "let x = a in f x".  If a is a free or
  1121 bound variable or a constant then the let is unfolded.  Otherwise
  1122 first a is simplified to b, and then f b is simplified to g. If
  1123 possible we abstract b from g arriving at "let x = b in h x",
  1124 otherwise we unfold the let and arrive at g.  The simproc can be
  1125 enabled/disabled by the reference use_let_simproc.  Potential
  1126 INCOMPATIBILITY since simplification is more powerful by default.
  1127 
  1128 * Classical reasoning: the meson method now accepts theorems as arguments.
  1129 
  1130 * Prover support: pre-release of the Isabelle-ATP linkup, which runs background
  1131 jobs to provide advice on the provability of subgoals.
  1132 
  1133 * Theory OrderedGroup and Ring_and_Field: various additions and
  1134 improvements to faciliate calculations involving equalities and
  1135 inequalities.
  1136 
  1137 The following theorems have been eliminated or modified
  1138 (INCOMPATIBILITY):
  1139 
  1140   abs_eq             now named abs_of_nonneg
  1141   abs_of_ge_0        now named abs_of_nonneg
  1142   abs_minus_eq       now named abs_of_nonpos
  1143   imp_abs_id         now named abs_of_nonneg
  1144   imp_abs_neg_id     now named abs_of_nonpos
  1145   mult_pos           now named mult_pos_pos
  1146   mult_pos_le        now named mult_nonneg_nonneg
  1147   mult_pos_neg_le    now named mult_nonneg_nonpos
  1148   mult_pos_neg2_le   now named mult_nonneg_nonpos2
  1149   mult_neg           now named mult_neg_neg
  1150   mult_neg_le        now named mult_nonpos_nonpos
  1151 
  1152 * Theory Parity: added rules for simplifying exponents.
  1153 
  1154 * Theory List:
  1155 
  1156 The following theorems have been eliminated or modified
  1157 (INCOMPATIBILITY):
  1158 
  1159   list_all_Nil       now named list_all.simps(1)
  1160   list_all_Cons      now named list_all.simps(2)
  1161   list_all_conv      now named list_all_iff
  1162   set_mem_eq         now named mem_iff
  1163 
  1164 * Theories SetsAndFunctions and BigO (see HOL/Library) support
  1165 asymptotic "big O" calculations.  See the notes in BigO.thy.
  1166 
  1167 
  1168 *** HOL-Complex ***
  1169 
  1170 * Theory RealDef: better support for embedding natural numbers and
  1171 integers in the reals.
  1172 
  1173 The following theorems have been eliminated or modified
  1174 (INCOMPATIBILITY):
  1175 
  1176   exp_ge_add_one_self  now requires no hypotheses
  1177   real_of_int_add      reversed direction of equality (use [symmetric])
  1178   real_of_int_minus    reversed direction of equality (use [symmetric])
  1179   real_of_int_diff     reversed direction of equality (use [symmetric])
  1180   real_of_int_mult     reversed direction of equality (use [symmetric])
  1181 
  1182 * Theory RComplete: expanded support for floor and ceiling functions.
  1183 
  1184 * Theory Ln is new, with properties of the natural logarithm
  1185 
  1186 * Hyperreal: There is a new type constructor "star" for making
  1187 nonstandard types.  The old type names are now type synonyms:
  1188 
  1189   hypreal = real star
  1190   hypnat = nat star
  1191   hcomplex = complex star
  1192 
  1193 * Hyperreal: Many groups of similarly-defined constants have been
  1194 replaced by polymorphic versions (INCOMPATIBILITY):
  1195 
  1196   star_of <-- hypreal_of_real, hypnat_of_nat, hcomplex_of_complex
  1197 
  1198   starset      <-- starsetNat, starsetC
  1199   *s*          <-- *sNat*, *sc*
  1200   starset_n    <-- starsetNat_n, starsetC_n
  1201   *sn*         <-- *sNatn*, *scn*
  1202   InternalSets <-- InternalNatSets, InternalCSets
  1203 
  1204   starfun      <-- starfun{Nat,Nat2,C,RC,CR}
  1205   *f*          <-- *fNat*, *fNat2*, *fc*, *fRc*, *fcR*
  1206   starfun_n    <-- starfun{Nat,Nat2,C,RC,CR}_n
  1207   *fn*         <-- *fNatn*, *fNat2n*, *fcn*, *fRcn*, *fcRn*
  1208   InternalFuns <-- InternalNatFuns, InternalNatFuns2, Internal{C,RC,CR}Funs
  1209 
  1210 * Hyperreal: Many type-specific theorems have been removed in favor of
  1211 theorems specific to various axiomatic type classes (INCOMPATIBILITY):
  1212 
  1213   add_commute <-- {hypreal,hypnat,hcomplex}_add_commute
  1214   add_assoc   <-- {hypreal,hypnat,hcomplex}_add_assocs
  1215   OrderedGroup.add_0 <-- {hypreal,hypnat,hcomplex}_add_zero_left
  1216   OrderedGroup.add_0_right <-- {hypreal,hcomplex}_add_zero_right
  1217   right_minus <-- hypreal_add_minus
  1218   left_minus <-- {hypreal,hcomplex}_add_minus_left
  1219   mult_commute <-- {hypreal,hypnat,hcomplex}_mult_commute
  1220   mult_assoc <-- {hypreal,hypnat,hcomplex}_mult_assoc
  1221   mult_1_left <-- {hypreal,hypnat}_mult_1, hcomplex_mult_one_left
  1222   mult_1_right <-- hcomplex_mult_one_right
  1223   mult_zero_left <-- hcomplex_mult_zero_left
  1224   left_distrib <-- {hypreal,hypnat,hcomplex}_add_mult_distrib
  1225   right_distrib <-- hypnat_add_mult_distrib2
  1226   zero_neq_one <-- {hypreal,hypnat,hcomplex}_zero_not_eq_one
  1227   right_inverse <-- hypreal_mult_inverse
  1228   left_inverse <-- hypreal_mult_inverse_left, hcomplex_mult_inv_left
  1229   order_refl <-- {hypreal,hypnat}_le_refl
  1230   order_trans <-- {hypreal,hypnat}_le_trans
  1231   order_antisym <-- {hypreal,hypnat}_le_anti_sym
  1232   order_less_le <-- {hypreal,hypnat}_less_le
  1233   linorder_linear <-- {hypreal,hypnat}_le_linear
  1234   add_left_mono <-- {hypreal,hypnat}_add_left_mono
  1235   mult_strict_left_mono <-- {hypreal,hypnat}_mult_less_mono2
  1236   add_nonneg_nonneg <-- hypreal_le_add_order
  1237 
  1238 * Hyperreal: Separate theorems having to do with type-specific
  1239 versions of constants have been merged into theorems that apply to the
  1240 new polymorphic constants (INCOMPATIBILITY):
  1241 
  1242   STAR_UNIV_set <-- {STAR_real,NatStar_real,STARC_complex}_set
  1243   STAR_empty_set <-- {STAR,NatStar,STARC}_empty_set
  1244   STAR_Un <-- {STAR,NatStar,STARC}_Un
  1245   STAR_Int <-- {STAR,NatStar,STARC}_Int
  1246   STAR_Compl <-- {STAR,NatStar,STARC}_Compl
  1247   STAR_subset <-- {STAR,NatStar,STARC}_subset
  1248   STAR_mem <-- {STAR,NatStar,STARC}_mem
  1249   STAR_mem_Compl <-- {STAR,STARC}_mem_Compl
  1250   STAR_diff <-- {STAR,STARC}_diff
  1251   STAR_star_of_image_subset <-- {STAR_hypreal_of_real, NatStar_hypreal_of_real,
  1252     STARC_hcomplex_of_complex}_image_subset
  1253   starset_n_Un <-- starset{Nat,C}_n_Un
  1254   starset_n_Int <-- starset{Nat,C}_n_Int
  1255   starset_n_Compl <-- starset{Nat,C}_n_Compl
  1256   starset_n_diff <-- starset{Nat,C}_n_diff
  1257   InternalSets_Un <-- Internal{Nat,C}Sets_Un
  1258   InternalSets_Int <-- Internal{Nat,C}Sets_Int
  1259   InternalSets_Compl <-- Internal{Nat,C}Sets_Compl
  1260   InternalSets_diff <-- Internal{Nat,C}Sets_diff
  1261   InternalSets_UNIV_diff <-- Internal{Nat,C}Sets_UNIV_diff
  1262   InternalSets_starset_n <-- Internal{Nat,C}Sets_starset{Nat,C}_n
  1263   starset_starset_n_eq <-- starset{Nat,C}_starset{Nat,C}_n_eq
  1264   starset_n_starset <-- starset{Nat,C}_n_starset{Nat,C}
  1265   starfun_n_starfun <-- starfun{Nat,Nat2,C,RC,CR}_n_starfun{Nat,Nat2,C,RC,CR}
  1266   starfun <-- starfun{Nat,Nat2,C,RC,CR}
  1267   starfun_mult <-- starfun{Nat,Nat2,C,RC,CR}_mult
  1268   starfun_add <-- starfun{Nat,Nat2,C,RC,CR}_add
  1269   starfun_minus <-- starfun{Nat,Nat2,C,RC,CR}_minus
  1270   starfun_diff <-- starfun{C,RC,CR}_diff
  1271   starfun_o <-- starfun{NatNat2,Nat2,_stafunNat,C,C_starfunRC,_starfunCR}_o
  1272   starfun_o2 <-- starfun{NatNat2,_stafunNat,C,C_starfunRC,_starfunCR}_o2
  1273   starfun_const_fun <-- starfun{Nat,Nat2,C,RC,CR}_const_fun
  1274   starfun_inverse <-- starfun{Nat,C,RC,CR}_inverse
  1275   starfun_eq <-- starfun{Nat,Nat2,C,RC,CR}_eq
  1276   starfun_eq_iff <-- starfun{C,RC,CR}_eq_iff
  1277   starfun_Id <-- starfunC_Id
  1278   starfun_approx <-- starfun{Nat,CR}_approx
  1279   starfun_capprox <-- starfun{C,RC}_capprox
  1280   starfun_abs <-- starfunNat_rabs
  1281   starfun_lambda_cancel <-- starfun{C,CR,RC}_lambda_cancel
  1282   starfun_lambda_cancel2 <-- starfun{C,CR,RC}_lambda_cancel2
  1283   starfun_mult_HFinite_approx <-- starfunCR_mult_HFinite_capprox
  1284   starfun_mult_CFinite_capprox <-- starfun{C,RC}_mult_CFinite_capprox
  1285   starfun_add_capprox <-- starfun{C,RC}_add_capprox
  1286   starfun_add_approx <-- starfunCR_add_approx
  1287   starfun_inverse_inverse <-- starfunC_inverse_inverse
  1288   starfun_divide <-- starfun{C,CR,RC}_divide
  1289   starfun_n <-- starfun{Nat,C}_n
  1290   starfun_n_mult <-- starfun{Nat,C}_n_mult
  1291   starfun_n_add <-- starfun{Nat,C}_n_add
  1292   starfun_n_add_minus <-- starfunNat_n_add_minus
  1293   starfun_n_const_fun <-- starfun{Nat,C}_n_const_fun
  1294   starfun_n_minus <-- starfun{Nat,C}_n_minus
  1295   starfun_n_eq <-- starfun{Nat,C}_n_eq
  1296 
  1297   star_n_add <-- {hypreal,hypnat,hcomplex}_add
  1298   star_n_minus <-- {hypreal,hcomplex}_minus
  1299   star_n_diff <-- {hypreal,hcomplex}_diff
  1300   star_n_mult <-- {hypreal,hcomplex}_mult
  1301   star_n_inverse <-- {hypreal,hcomplex}_inverse
  1302   star_n_le <-- {hypreal,hypnat}_le
  1303   star_n_less <-- {hypreal,hypnat}_less
  1304   star_n_zero_num <-- {hypreal,hypnat,hcomplex}_zero_num
  1305   star_n_one_num <-- {hypreal,hypnat,hcomplex}_one_num
  1306   star_n_abs <-- hypreal_hrabs
  1307   star_n_divide <-- hcomplex_divide
  1308 
  1309   star_of_add <-- {hypreal_of_real,hypnat_of_nat,hcomplex_of_complex}_add
  1310   star_of_minus <-- {hypreal_of_real,hcomplex_of_complex}_minus
  1311   star_of_diff <-- hypreal_of_real_diff
  1312   star_of_mult <-- {hypreal_of_real,hypnat_of_nat,hcomplex_of_complex}_mult
  1313   star_of_one <-- {hypreal_of_real,hcomplex_of_complex}_one
  1314   star_of_zero <-- {hypreal_of_real,hypnat_of_nat,hcomplex_of_complex}_zero
  1315   star_of_le <-- {hypreal_of_real,hypnat_of_nat}_le_iff
  1316   star_of_less <-- {hypreal_of_real,hypnat_of_nat}_less_iff
  1317   star_of_eq <-- {hypreal_of_real,hypnat_of_nat,hcomplex_of_complex}_eq_iff
  1318   star_of_inverse <-- {hypreal_of_real,hcomplex_of_complex}_inverse
  1319   star_of_divide <-- {hypreal_of_real,hcomplex_of_complex}_divide
  1320   star_of_of_nat <-- {hypreal_of_real,hcomplex_of_complex}_of_nat
  1321   star_of_of_int <-- {hypreal_of_real,hcomplex_of_complex}_of_int
  1322   star_of_number_of <-- {hypreal,hcomplex}_number_of
  1323   star_of_number_less <-- number_of_less_hypreal_of_real_iff
  1324   star_of_number_le <-- number_of_le_hypreal_of_real_iff
  1325   star_of_eq_number <-- hypreal_of_real_eq_number_of_iff
  1326   star_of_less_number <-- hypreal_of_real_less_number_of_iff
  1327   star_of_le_number <-- hypreal_of_real_le_number_of_iff
  1328   star_of_power <-- hypreal_of_real_power
  1329   star_of_eq_0 <-- hcomplex_of_complex_zero_iff
  1330 
  1331 * Hyperreal: new method "transfer" that implements the transfer
  1332 principle of nonstandard analysis. With a subgoal that mentions
  1333 nonstandard types like "'a star", the command "apply transfer"
  1334 replaces it with an equivalent one that mentions only standard types.
  1335 To be successful, all free variables must have standard types; non-
  1336 standard variables must have explicit universal quantifiers.
  1337 
  1338 * Hyperreal: A theory of Taylor series.
  1339 
  1340 
  1341 *** HOLCF ***
  1342 
  1343 * Discontinued special version of 'constdefs' (which used to support
  1344 continuous functions) in favor of the general Pure one with full
  1345 type-inference.
  1346 
  1347 * New simplification procedure for solving continuity conditions; it
  1348 is much faster on terms with many nested lambda abstractions (cubic
  1349 instead of exponential time).
  1350 
  1351 * New syntax for domain package: selector names are now optional.
  1352 Parentheses should be omitted unless argument is lazy, for example:
  1353 
  1354   domain 'a stream = cons "'a" (lazy "'a stream")
  1355 
  1356 * New command 'fixrec' for defining recursive functions with pattern
  1357 matching; defining multiple functions with mutual recursion is also
  1358 supported.  Patterns may include the constants cpair, spair, up, sinl,
  1359 sinr, or any data constructor defined by the domain package. The given
  1360 equations are proven as rewrite rules. See HOLCF/ex/Fixrec_ex.thy for
  1361 syntax and examples.
  1362 
  1363 * New commands 'cpodef' and 'pcpodef' for defining predicate subtypes
  1364 of cpo and pcpo types. Syntax is exactly like the 'typedef' command,
  1365 but the proof obligation additionally includes an admissibility
  1366 requirement. The packages generate instances of class cpo or pcpo,
  1367 with continuity and strictness theorems for Rep and Abs.
  1368 
  1369 * HOLCF: Many theorems have been renamed according to a more standard naming
  1370 scheme (INCOMPATIBILITY):
  1371 
  1372   foo_inject:  "foo$x = foo$y ==> x = y"
  1373   foo_eq:      "(foo$x = foo$y) = (x = y)"
  1374   foo_less:    "(foo$x << foo$y) = (x << y)"
  1375   foo_strict:  "foo$UU = UU"
  1376   foo_defined: "... ==> foo$x ~= UU"
  1377   foo_defined_iff: "(foo$x = UU) = (x = UU)"
  1378 
  1379 
  1380 *** ZF ***
  1381 
  1382 * ZF/ex: theories Group and Ring provide examples in abstract algebra,
  1383 including the First Isomorphism Theorem (on quotienting by the kernel
  1384 of a homomorphism).
  1385 
  1386 * ZF/Simplifier: install second copy of type solver that actually
  1387 makes use of TC rules declared to Isar proof contexts (or locales);
  1388 the old version is still required for ML proof scripts.
  1389 
  1390 
  1391 *** Cube ***
  1392 
  1393 * Converted to Isar theory format; use locales instead of axiomatic
  1394 theories.
  1395 
  1396 
  1397 *** ML ***
  1398 
  1399 * Pure/library.ML no longer defines its own option datatype, but uses
  1400 that of the SML basis, which has constructors NONE and SOME instead of
  1401 None and Some, as well as exception Option.Option instead of OPTION.
  1402 The functions the, if_none, is_some, is_none have been adapted
  1403 accordingly, while Option.map replaces apsome.
  1404 
  1405 * Pure/library.ML: the exception LIST has been given up in favour of
  1406 the standard exceptions Empty and Subscript, as well as
  1407 Library.UnequalLengths.  Function like Library.hd and Library.tl are
  1408 superceded by the standard hd and tl functions etc.
  1409 
  1410 A number of basic list functions are no longer exported to the ML
  1411 toplevel, as they are variants of predefined functions.  The following
  1412 suggests how one can translate existing code:
  1413 
  1414     rev_append xs ys = List.revAppend (xs, ys)
  1415     nth_elem (i, xs) = List.nth (xs, i)
  1416     last_elem xs = List.last xs
  1417     flat xss = List.concat xss
  1418     seq fs = List.app fs
  1419     partition P xs = List.partition P xs
  1420     mapfilter f xs = List.mapPartial f xs
  1421 
  1422 * Pure/library.ML: several combinators for linear functional
  1423 transformations, notably reverse application and composition:
  1424 
  1425   x |> f                f #> g
  1426   (x, y) |-> f          f #-> g
  1427 
  1428 * Pure/library.ML: introduced/changed precedence of infix operators:
  1429 
  1430   infix 1 |> |-> ||> ||>> |>> |>>> #> #->;
  1431   infix 2 ?;
  1432   infix 3 o oo ooo oooo;
  1433   infix 4 ~~ upto downto;
  1434 
  1435 Maybe INCOMPATIBILITY when any of those is used in conjunction with other
  1436 infix operators.
  1437 
  1438 * Pure/library.ML: natural list combinators fold, fold_rev, and
  1439 fold_map support linear functional transformations and nesting.  For
  1440 example:
  1441 
  1442   fold f [x1, ..., xN] y =
  1443     y |> f x1 |> ... |> f xN
  1444 
  1445   (fold o fold) f [xs1, ..., xsN] y =
  1446     y |> fold f xs1 |> ... |> fold f xsN
  1447 
  1448   fold f [x1, ..., xN] =
  1449     f x1 #> ... #> f xN
  1450 
  1451   (fold o fold) f [xs1, ..., xsN] =
  1452     fold f xs1 #> ... #> fold f xsN
  1453 
  1454 * Pure/library.ML: the following selectors on type 'a option are
  1455 available:
  1456 
  1457   the:               'a option -> 'a  (*partial*)
  1458   these:             'a option -> 'a  where 'a = 'b list
  1459   the_default: 'a -> 'a option -> 'a
  1460   the_list:          'a option -> 'a list
  1461 
  1462 * Pure/General: structure AList (cf. Pure/General/alist.ML) provides
  1463 basic operations for association lists, following natural argument
  1464 order; moreover the explicit equality predicate passed here avoids
  1465 potentially expensive polymorphic runtime equality checks.
  1466 The old functions may be expressed as follows:
  1467 
  1468   assoc = uncurry (AList.lookup (op =))
  1469   assocs = these oo AList.lookup (op =)
  1470   overwrite = uncurry (AList.update (op =)) o swap
  1471 
  1472 * Pure/General: structure AList (cf. Pure/General/alist.ML) provides
  1473 
  1474   val make: ('a -> 'b) -> 'a list -> ('a * 'b) list
  1475   val find: ('a * 'b -> bool) -> ('c * 'b) list -> 'a -> 'c list
  1476 
  1477 replacing make_keylist and keyfilter (occassionally used)
  1478 Naive rewrites:
  1479 
  1480   make_keylist = AList.make
  1481   keyfilter = AList.find (op =)
  1482 
  1483 * eq_fst and eq_snd now take explicit equality parameter, thus
  1484   avoiding eqtypes. Naive rewrites:
  1485 
  1486     eq_fst = eq_fst (op =)
  1487     eq_snd = eq_snd (op =)
  1488 
  1489 * Removed deprecated apl and apr (rarely used).
  1490   Naive rewrites:
  1491 
  1492     apl (n, op) =>>= curry op n
  1493     apr (op, m) =>>= fn n => op (n, m)
  1494 
  1495 * Pure/General: structure OrdList (cf. Pure/General/ord_list.ML)
  1496 provides a reasonably efficient light-weight implementation of sets as
  1497 lists.
  1498 
  1499 * Pure/General: generic tables (cf. Pure/General/table.ML) provide a
  1500 few new operations; existing lookup and update are now curried to
  1501 follow natural argument order (for use with fold etc.);
  1502 INCOMPATIBILITY, use (uncurry Symtab.lookup) etc. as last resort.
  1503 
  1504 * Pure/General: output via the Isabelle channels of
  1505 writeln/warning/error etc. is now passed through Output.output, with a
  1506 hook for arbitrary transformations depending on the print_mode
  1507 (cf. Output.add_mode -- the first active mode that provides a output
  1508 function wins).  Already formatted output may be embedded into further
  1509 text via Output.raw; the result of Pretty.string_of/str_of and derived
  1510 functions (string_of_term/cterm/thm etc.) is already marked raw to
  1511 accommodate easy composition of diagnostic messages etc.  Programmers
  1512 rarely need to care about Output.output or Output.raw at all, with
  1513 some notable exceptions: Output.output is required when bypassing the
  1514 standard channels (writeln etc.), or in token translations to produce
  1515 properly formatted results; Output.raw is required when capturing
  1516 already output material that will eventually be presented to the user
  1517 a second time.  For the default print mode, both Output.output and
  1518 Output.raw have no effect.
  1519 
  1520 * Pure/General: Output.time_accumulator NAME creates an operator ('a
  1521 -> 'b) -> 'a -> 'b to measure runtime and count invocations; the
  1522 cumulative results are displayed at the end of a batch session.
  1523 
  1524 * Pure/General: File.sysify_path and File.quote_sysify path have been
  1525 replaced by File.platform_path and File.shell_path (with appropriate
  1526 hooks).  This provides a clean interface for unusual systems where the
  1527 internal and external process view of file names are different.
  1528 
  1529 * Pure: more efficient orders for basic syntactic entities: added
  1530 fast_string_ord, fast_indexname_ord, fast_term_ord; changed sort_ord
  1531 and typ_ord to use fast_string_ord and fast_indexname_ord (term_ord is
  1532 NOT affected); structures Symtab, Vartab, Typtab, Termtab use the fast
  1533 orders now -- potential INCOMPATIBILITY for code that depends on a
  1534 particular order for Symtab.keys, Symtab.dest, etc. (consider using
  1535 Library.sort_strings on result).
  1536 
  1537 * Pure/term.ML: combinators fold_atyps, fold_aterms, fold_term_types,
  1538 fold_types traverse types/terms from left to right, observing natural
  1539 argument order.  Supercedes previous foldl_XXX versions, add_frees,
  1540 add_vars etc. have been adapted as well: INCOMPATIBILITY.
  1541 
  1542 * Pure: name spaces have been refined, with significant changes of the
  1543 internal interfaces -- INCOMPATIBILITY.  Renamed cond_extern(_table)
  1544 to extern(_table).  The plain name entry path is superceded by a
  1545 general 'naming' context, which also includes the 'policy' to produce
  1546 a fully qualified name and external accesses of a fully qualified
  1547 name; NameSpace.extend is superceded by context dependent
  1548 Sign.declare_name.  Several theory and proof context operations modify
  1549 the naming context.  Especially note Theory.restore_naming and
  1550 ProofContext.restore_naming to get back to a sane state; note that
  1551 Theory.add_path is no longer sufficient to recover from
  1552 Theory.absolute_path in particular.
  1553 
  1554 * Pure: new flags short_names (default false) and unique_names
  1555 (default true) for controlling output of qualified names.  If
  1556 short_names is set, names are printed unqualified.  If unique_names is
  1557 reset, the name prefix is reduced to the minimum required to achieve
  1558 the original result when interning again, even if there is an overlap
  1559 with earlier declarations.
  1560 
  1561 * Pure/TheoryDataFun: change of the argument structure; 'prep_ext' is
  1562 now 'extend', and 'merge' gets an additional Pretty.pp argument
  1563 (useful for printing error messages).  INCOMPATIBILITY.
  1564 
  1565 * Pure: major reorganization of the theory context.  Type Sign.sg and
  1566 Theory.theory are now identified, referring to the universal
  1567 Context.theory (see Pure/context.ML).  Actual signature and theory
  1568 content is managed as theory data.  The old code and interfaces were
  1569 spread over many files and structures; the new arrangement introduces
  1570 considerable INCOMPATIBILITY to gain more clarity:
  1571 
  1572   Context -- theory management operations (name, identity, inclusion,
  1573     parents, ancestors, merge, etc.), plus generic theory data;
  1574 
  1575   Sign -- logical signature and syntax operations (declaring consts,
  1576     types, etc.), plus certify/read for common entities;
  1577 
  1578   Theory -- logical theory operations (stating axioms, definitions,
  1579     oracles), plus a copy of logical signature operations (consts,
  1580     types, etc.); also a few basic management operations (Theory.copy,
  1581     Theory.merge, etc.)
  1582 
  1583 The most basic sign_of operations (Theory.sign_of, Thm.sign_of_thm
  1584 etc.) as well as the sign field in Thm.rep_thm etc. have been retained
  1585 for convenience -- they merely return the theory.
  1586 
  1587 * Pure: type Type.tsig is superceded by theory in most interfaces.
  1588 
  1589 * Pure: the Isar proof context type is already defined early in Pure
  1590 as Context.proof (note that ProofContext.context and Proof.context are
  1591 aliases, where the latter is the preferred name).  This enables other
  1592 Isabelle components to refer to that type even before Isar is present.
  1593 
  1594 * Pure/sign/theory: discontinued named name spaces (i.e. classK,
  1595 typeK, constK, axiomK, oracleK), but provide explicit operations for
  1596 any of these kinds.  For example, Sign.intern typeK is now
  1597 Sign.intern_type, Theory.hide_space Sign.typeK is now
  1598 Theory.hide_types.  Also note that former
  1599 Theory.hide_classes/types/consts are now
  1600 Theory.hide_classes_i/types_i/consts_i, while the non '_i' versions
  1601 internalize their arguments!  INCOMPATIBILITY.
  1602 
  1603 * Pure: get_thm interface (of PureThy and ProofContext) expects
  1604 datatype thmref (with constructors Name and NameSelection) instead of
  1605 plain string -- INCOMPATIBILITY;
  1606 
  1607 * Pure: cases produced by proof methods specify options, where NONE
  1608 means to remove case bindings -- INCOMPATIBILITY in
  1609 (RAW_)METHOD_CASES.
  1610 
  1611 * Pure: the following operations retrieve axioms or theorems from a
  1612 theory node or theory hierarchy, respectively:
  1613 
  1614   Theory.axioms_of: theory -> (string * term) list
  1615   Theory.all_axioms_of: theory -> (string * term) list
  1616   PureThy.thms_of: theory -> (string * thm) list
  1617   PureThy.all_thms_of: theory -> (string * thm) list
  1618 
  1619 * Pure: print_tac now outputs the goal through the trace channel.
  1620 
  1621 * Isar toplevel: improved diagnostics, mostly for Poly/ML only.
  1622 Reference Toplevel.debug (default false) controls detailed printing
  1623 and tracing of low-level exceptions; Toplevel.profiling (default 0)
  1624 controls execution profiling -- set to 1 for time and 2 for space
  1625 (both increase the runtime).
  1626 
  1627 * Isar session: The initial use of ROOT.ML is now always timed,
  1628 i.e. the log will show the actual process times, in contrast to the
  1629 elapsed wall-clock time that the outer shell wrapper produces.
  1630 
  1631 * Simplifier: improved handling of bound variables (nameless
  1632 representation, avoid allocating new strings).  Simprocs that invoke
  1633 the Simplifier recursively should use Simplifier.inherit_bounds to
  1634 avoid local name clashes.  Failure to do so produces warnings
  1635 "Simplifier: renamed bound variable ..."; set Simplifier.debug_bounds
  1636 for further details.
  1637 
  1638 * ML functions legacy_bindings and use_legacy_bindings produce ML fact
  1639 bindings for all theorems stored within a given theory; this may help
  1640 in porting non-Isar theories to Isar ones, while keeping ML proof
  1641 scripts for the time being.
  1642 
  1643 * ML operator HTML.with_charset specifies the charset begin used for
  1644 generated HTML files.  For example:
  1645 
  1646   HTML.with_charset "utf-8" use_thy "Hebrew";
  1647   HTML.with_charset "utf-8" use_thy "Chinese";
  1648 
  1649 
  1650 *** System ***
  1651 
  1652 * Allow symlinks to all proper Isabelle executables (Isabelle,
  1653 isabelle, isatool etc.).
  1654 
  1655 * ISABELLE_DOC_FORMAT setting specifies preferred document format (for
  1656 isatool doc, isatool mkdir, display_drafts etc.).
  1657 
  1658 * isatool usedir: option -f allows specification of the ML file to be
  1659 used by Isabelle; default is ROOT.ML.
  1660 
  1661 * New isatool version outputs the version identifier of the Isabelle
  1662 distribution being used.
  1663 
  1664 * HOL: new isatool dimacs2hol converts files in DIMACS CNF format
  1665 (containing Boolean satisfiability problems) into Isabelle/HOL
  1666 theories.
  1667 
  1668 
  1669 
  1670 New in Isabelle2004 (April 2004)
  1671 --------------------------------
  1672 
  1673 *** General ***
  1674 
  1675 * Provers/order.ML:  new efficient reasoner for partial and linear orders.
  1676   Replaces linorder.ML.
  1677 
  1678 * Pure: Greek letters (except small lambda, \<lambda>), as well as Gothic
  1679   (\<aa>...\<zz>\<AA>...\<ZZ>), calligraphic (\<A>...\<Z>), and Euler
  1680   (\<a>...\<z>), are now considered normal letters, and can therefore
  1681   be used anywhere where an ASCII letter (a...zA...Z) has until
  1682   now. COMPATIBILITY: This obviously changes the parsing of some
  1683   terms, especially where a symbol has been used as a binder, say
  1684   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed
  1685   as an identifier.  Fix it by inserting a space around former
  1686   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in
  1687   existing theory and ML files.
  1688 
  1689 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.
  1690 
  1691 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now
  1692   allowed in identifiers. Similar to Greek letters \<^isub> is now considered
  1693   a normal (but invisible) letter. For multiple letter subscripts repeat
  1694   \<^isub> like this: x\<^isub>1\<^isub>2.
  1695 
  1696 * Pure: There are now sub-/superscripts that can span more than one
  1697   character. Text between \<^bsub> and \<^esub> is set in subscript in
  1698   ProofGeneral and LaTeX, text between \<^bsup> and \<^esup> in
  1699   superscript. The new control characters are not identifier parts.
  1700 
  1701 * Pure: Control-symbols of the form \<^raw:...> will literally print the
  1702   content of "..." to the latex file instead of \isacntrl... . The "..."
  1703   may consist of any printable characters excluding the end bracket >.
  1704 
  1705 * Pure: Using new Isar command "finalconsts" (or the ML functions
  1706   Theory.add_finals or Theory.add_finals_i) it is now possible to
  1707   declare constants "final", which prevents their being given a definition
  1708   later.  It is useful for constants whose behaviour is fixed axiomatically
  1709   rather than definitionally, such as the meta-logic connectives.
  1710 
  1711 * Pure: 'instance' now handles general arities with general sorts
  1712   (i.e. intersections of classes),
  1713 
  1714 * Presentation: generated HTML now uses a CSS style sheet to make layout
  1715   (somewhat) independent of content. It is copied from lib/html/isabelle.css.
  1716   It can be changed to alter the colors/layout of generated pages.
  1717 
  1718 
  1719 *** Isar ***
  1720 
  1721 * Tactic emulation methods rule_tac, erule_tac, drule_tac, frule_tac,
  1722   cut_tac, subgoal_tac and thin_tac:
  1723   - Now understand static (Isar) contexts.  As a consequence, users of Isar
  1724     locales are no longer forced to write Isar proof scripts.
  1725     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
  1726     emulations.
  1727   - INCOMPATIBILITY: names of variables to be instantiated may no
  1728     longer be enclosed in quotes.  Instead, precede variable name with `?'.
  1729     This is consistent with the instantiation attribute "where".
  1730 
  1731 * Attributes "where" and "of":
  1732   - Now take type variables of instantiated theorem into account when reading
  1733     the instantiation string.  This fixes a bug that caused instantiated
  1734     theorems to have too special types in some circumstances.
  1735   - "where" permits explicit instantiations of type variables.
  1736 
  1737 * Calculation commands "moreover" and "also" no longer interfere with
  1738   current facts ("this"), admitting arbitrary combinations with "then"
  1739   and derived forms.
  1740 
  1741 * Locales:
  1742   - Goal statements involving the context element "includes" no longer
  1743     generate theorems with internal delta predicates (those ending on
  1744     "_axioms") in the premise.
  1745     Resolve particular premise with <locale>.intro to obtain old form.
  1746   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
  1747     specification and "includes" elements in goal statement.
  1748   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
  1749     [intro?] and [elim?] (respectively) by default.
  1750   - Experimental command for instantiation of locales in proof contexts:
  1751         instantiate <label>[<attrs>]: <loc>
  1752     Instantiates locale <loc> and adds all its theorems to the current context
  1753     taking into account their attributes.  Label and attrs are optional
  1754     modifiers, like in theorem declarations.  If present, names of
  1755     instantiated theorems are qualified with <label>, and the attributes
  1756     <attrs> are applied after any attributes these theorems might have already.
  1757       If the locale has assumptions, a chained fact of the form
  1758     "<loc> t1 ... tn" is expected from which instantiations of the parameters
  1759     are derived.  The command does not support old-style locales declared
  1760     with "locale (open)".
  1761       A few (very simple) examples can be found in FOL/ex/LocaleInst.thy.
  1762 
  1763 * HOL: Tactic emulation methods induct_tac and case_tac understand static
  1764   (Isar) contexts.
  1765 
  1766 
  1767 *** HOL ***
  1768 
  1769 * Proof import: new image HOL4 contains the imported library from
  1770   the HOL4 system with about 2500 theorems. It is imported by
  1771   replaying proof terms produced by HOL4 in Isabelle. The HOL4 image
  1772   can be used like any other Isabelle image.  See
  1773   HOL/Import/HOL/README for more information.
  1774 
  1775 * Simplifier:
  1776   - Much improved handling of linear and partial orders.
  1777     Reasoners for linear and partial orders are set up for type classes
  1778     "linorder" and "order" respectively, and are added to the default simpset
  1779     as solvers.  This means that the simplifier can build transitivity chains
  1780     to solve goals from the assumptions.
  1781   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications
  1782     of blast or auto after simplification become unnecessary because the goal
  1783     is solved by simplification already.
  1784 
  1785 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws,
  1786     all proved in axiomatic type classes for semirings, rings and fields.
  1787 
  1788 * Numerics:
  1789   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are
  1790     now formalized using the Ring_and_Field theory mentioned above.
  1791   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently
  1792     than before, because now they are set up once in a generic manner.
  1793   - INCOMPATIBILITY: many type-specific arithmetic laws have gone.
  1794     Look for the general versions in Ring_and_Field (and Power if they concern
  1795     exponentiation).
  1796 
  1797 * Type "rat" of the rational numbers is now available in HOL-Complex.
  1798 
  1799 * Records:
  1800   - Record types are now by default printed with their type abbreviation
  1801     instead of the list of all field types. This can be configured via
  1802     the reference "print_record_type_abbr".
  1803   - Simproc "record_upd_simproc" for simplification of multiple updates added
  1804     (not enabled by default).
  1805   - Simproc "record_ex_sel_eq_simproc" to simplify EX x. sel r = x resp.
  1806     EX x. x = sel r to True (not enabled by default).
  1807   - Tactic "record_split_simp_tac" to split and simplify records added.
  1808 
  1809 * 'specification' command added, allowing for definition by
  1810   specification.  There is also an 'ax_specification' command that
  1811   introduces the new constants axiomatically.
  1812 
  1813 * arith(_tac) is now able to generate counterexamples for reals as well.
  1814 
  1815 * HOL-Algebra: new locale "ring" for non-commutative rings.
  1816 
  1817 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
  1818   definitions, thanks to Sava Krsti\'{c} and John Matthews.
  1819 
  1820 * HOL-Matrix: a first theory for matrices in HOL with an application of
  1821   matrix theory to linear programming.
  1822 
  1823 * Unions and Intersections:
  1824   The latex output syntax of UN and INT has been changed
  1825   from "\Union x \in A. B" to "\Union_{x \in A} B"
  1826   i.e. the index formulae has become a subscript.
  1827   Similarly for "\Union x. B", and for \Inter instead of \Union.
  1828 
  1829 * Unions and Intersections over Intervals:
  1830   There is new short syntax "UN i<=n. A" for "UN i:{0..n}. A". There is
  1831   also an x-symbol version with subscripts "\<Union>\<^bsub>i <= n\<^esub>. A"
  1832   like in normal math, and corresponding versions for < and for intersection.
  1833 
  1834 * HOL/List: Ordering "lexico" is renamed "lenlex" and the standard
  1835   lexicographic dictonary ordering has been added as "lexord".
  1836 
  1837 * ML: the legacy theory structures Int and List have been removed. They had
  1838   conflicted with ML Basis Library structures having the same names.
  1839 
  1840 * 'refute' command added to search for (finite) countermodels.  Only works
  1841   for a fragment of HOL.  The installation of an external SAT solver is
  1842   highly recommended.  See "HOL/Refute.thy" for details.
  1843 
  1844 * 'quickcheck' command: Allows to find counterexamples by evaluating
  1845   formulae under an assignment of free variables to random values.
  1846   In contrast to 'refute', it can deal with inductive datatypes,
  1847   but cannot handle quantifiers. See "HOL/ex/Quickcheck_Examples.thy"
  1848   for examples.
  1849 
  1850 
  1851 *** HOLCF ***
  1852 
  1853 * Streams now come with concatenation and are part of the HOLCF image
  1854 
  1855 
  1856 
  1857 New in Isabelle2003 (May 2003)
  1858 ------------------------------
  1859 
  1860 *** General ***
  1861 
  1862 * Provers/simplifier:
  1863 
  1864   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
  1865     Assumptions are now subject to complete mutual simplification,
  1866     not just from left to right. The simplifier now preserves
  1867     the order of assumptions.
  1868 
  1869     Potential INCOMPATIBILITY:
  1870 
  1871     -- simp sometimes diverges where the old version did
  1872        not, e.g. invoking simp on the goal
  1873 
  1874         [| P (f x); y = x; f x = f y |] ==> Q
  1875 
  1876        now gives rise to the infinite reduction sequence
  1877 
  1878         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
  1879 
  1880        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
  1881        kind of problem.
  1882 
  1883     -- Tactics combining classical reasoner and simplification (such as auto)
  1884        are also affected by this change, because many of them rely on
  1885        simp. They may sometimes diverge as well or yield a different numbers
  1886        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
  1887        in case of problems. Sometimes subsequent calls to the classical
  1888        reasoner will fail because a preceeding call to the simplifier too
  1889        eagerly simplified the goal, e.g. deleted redundant premises.
  1890 
  1891   - The simplifier trace now shows the names of the applied rewrite rules
  1892 
  1893   - You can limit the number of recursive invocations of the simplifier
  1894     during conditional rewriting (where the simplifie tries to solve the
  1895     conditions before applying the rewrite rule):
  1896     ML "simp_depth_limit := n"
  1897     where n is an integer. Thus you can force termination where previously
  1898     the simplifier would diverge.
  1899 
  1900   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
  1901 
  1902   - No longer aborts on failed congruence proof.  Instead, the
  1903     congruence is ignored.
  1904 
  1905 * Pure: New generic framework for extracting programs from constructive
  1906   proofs. See HOL/Extraction.thy for an example instantiation, as well
  1907   as HOL/Extraction for some case studies.
  1908 
  1909 * Pure: The main goal of the proof state is no longer shown by default, only
  1910 the subgoals. This behaviour is controlled by a new flag.
  1911    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
  1912 (ML: Proof.show_main_goal).
  1913 
  1914 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
  1915 rules whose conclusion matches subgoal 1:
  1916       PG menu: Isabelle/Isar -> Show me -> matching rules
  1917 The rules are ordered by how closely they match the subgoal.
  1918 In particular, rules that solve a subgoal outright are displayed first
  1919 (or rather last, the way they are printed).
  1920 (ML: ProofGeneral.print_intros())
  1921 
  1922 * Pure: New flag trace_unify_fail causes unification to print
  1923 diagnostic information (PG: in trace buffer) when it fails. This is
  1924 useful for figuring out why single step proofs like rule, erule or
  1925 assumption failed.
  1926 
  1927 * Pure: Locale specifications now produce predicate definitions
  1928 according to the body of text (covering assumptions modulo local
  1929 definitions); predicate "loc_axioms" covers newly introduced text,
  1930 while "loc" is cumulative wrt. all included locale expressions; the
  1931 latter view is presented only on export into the global theory
  1932 context; potential INCOMPATIBILITY, use "(open)" option to fall back
  1933 on the old view without predicates;
  1934 
  1935 * Pure: predefined locales "var" and "struct" are useful for sharing
  1936 parameters (as in CASL, for example); just specify something like
  1937 ``var x + var y + struct M'' as import;
  1938 
  1939 * Pure: improved thms_containing: proper indexing of facts instead of
  1940 raw theorems; check validity of results wrt. current name space;
  1941 include local facts of proof configuration (also covers active
  1942 locales), cover fixed variables in index; may use "_" in term
  1943 specification; an optional limit for the number of printed facts may
  1944 be given (the default is 40);
  1945 
  1946 * Pure: disallow duplicate fact bindings within new-style theory files
  1947 (batch-mode only);
  1948 
  1949 * Provers: improved induct method: assumptions introduced by case
  1950 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
  1951 the goal statement); "foo" still refers to all facts collectively;
  1952 
  1953 * Provers: the function blast.overloaded has been removed: all constants
  1954 are regarded as potentially overloaded, which improves robustness in exchange
  1955 for slight decrease in efficiency;
  1956 
  1957 * Provers/linorder: New generic prover for transitivity reasoning over
  1958 linear orders.  Note: this prover is not efficient!
  1959 
  1960 * Isar: preview of problems to finish 'show' now produce an error
  1961 rather than just a warning (in interactive mode);
  1962 
  1963 
  1964 *** HOL ***
  1965 
  1966 * arith(_tac)
  1967 
  1968  - Produces a counter example if it cannot prove a goal.
  1969    Note that the counter example may be spurious if the goal is not a formula
  1970    of quantifier-free linear arithmetic.
  1971    In ProofGeneral the counter example appears in the trace buffer.
  1972 
  1973  - Knows about div k and mod k where k is a numeral of type nat or int.
  1974 
  1975  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
  1976    linear arithmetic fails. This takes account of quantifiers and divisibility.
  1977    Presburger arithmetic can also be called explicitly via presburger(_tac).
  1978 
  1979 * simp's arithmetic capabilities have been enhanced a bit: it now
  1980 takes ~= in premises into account (by performing a case split);
  1981 
  1982 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
  1983 are distributed over a sum of terms;
  1984 
  1985 * New tactic "trans_tac" and method "trans" instantiate
  1986 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
  1987 "<=", "<" and "=").
  1988 
  1989 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main
  1990 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
  1991 
  1992 * 'typedef' command has new option "open" to suppress the set
  1993 definition;
  1994 
  1995 * functions Min and Max on finite sets have been introduced (theory
  1996 Finite_Set);
  1997 
  1998 * attribute [symmetric] now works for relations as well; it turns
  1999 (x,y) : R^-1 into (y,x) : R, and vice versa;
  2000 
  2001 * induct over a !!-quantified statement (say !!x1..xn):
  2002   each "case" automatically performs "fix x1 .. xn" with exactly those names.
  2003 
  2004 * Map: `empty' is no longer a constant but a syntactic abbreviation for
  2005 %x. None. Warning: empty_def now refers to the previously hidden definition
  2006 of the empty set.
  2007 
  2008 * Algebra: formalization of classical algebra.  Intended as base for
  2009 any algebraic development in Isabelle.  Currently covers group theory
  2010 (up to Sylow's theorem) and ring theory (Universal Property of
  2011 Univariate Polynomials).  Contributions welcome;
  2012 
  2013 * GroupTheory: deleted, since its material has been moved to Algebra;
  2014 
  2015 * Complex: new directory of the complex numbers with numeric constants,
  2016 nonstandard complex numbers, and some complex analysis, standard and
  2017 nonstandard (Jacques Fleuriot);
  2018 
  2019 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
  2020 
  2021 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques
  2022 Fleuriot);
  2023 
  2024 * Real/HahnBanach: updated and adapted to locales;
  2025 
  2026 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
  2027 Gray and Kramer);
  2028 
  2029 * UNITY: added the Meier-Sanders theory of progress sets;
  2030 
  2031 * MicroJava: bytecode verifier and lightweight bytecode verifier
  2032 as abstract algorithms, instantiated to the JVM;
  2033 
  2034 * Bali: Java source language formalization. Type system, operational
  2035 semantics, axiomatic semantics. Supported language features:
  2036 classes, interfaces, objects,virtual methods, static methods,
  2037 static/instance fields, arrays, access modifiers, definite
  2038 assignment, exceptions.
  2039 
  2040 
  2041 *** ZF ***
  2042 
  2043 * ZF/Constructible: consistency proof for AC (Gdel's constructible
  2044 universe, etc.);
  2045 
  2046 * Main ZF: virtually all theories converted to new-style format;
  2047 
  2048 
  2049 *** ML ***
  2050 
  2051 * Pure: Tactic.prove provides sane interface for internal proofs;
  2052 omits the infamous "standard" operation, so this is more appropriate
  2053 than prove_goalw_cterm in many situations (e.g. in simprocs);
  2054 
  2055 * Pure: improved error reporting of simprocs;
  2056 
  2057 * Provers: Simplifier.simproc(_i) provides sane interface for setting
  2058 up simprocs;
  2059 
  2060 
  2061 *** Document preparation ***
  2062 
  2063 * uses \par instead of \\ for line breaks in theory text. This may
  2064 shift some page breaks in large documents. To get the old behaviour
  2065 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
  2066 
  2067 * minimized dependencies of isabelle.sty and isabellesym.sty on
  2068 other packages
  2069 
  2070 * \<euro> now needs package babel/greek instead of marvosym (which
  2071 broke \Rightarrow)
  2072 
  2073 * normal size for \<zero>...\<nine> (uses \mathbf instead of
  2074 textcomp package)
  2075 
  2076 
  2077 
  2078 New in Isabelle2002 (March 2002)
  2079 --------------------------------
  2080 
  2081 *** Document preparation ***
  2082 
  2083 * greatly simplified document preparation setup, including more
  2084 graceful interpretation of isatool usedir -i/-d/-D options, and more
  2085 instructive isatool mkdir; users should basically be able to get
  2086 started with "isatool mkdir HOL Test && isatool make"; alternatively,
  2087 users may run a separate document processing stage manually like this:
  2088 "isatool usedir -D output HOL Test && isatool document Test/output";
  2089 
  2090 * theory dependency graph may now be incorporated into documents;
  2091 isatool usedir -g true will produce session_graph.eps/.pdf for use
  2092 with \includegraphics of LaTeX;
  2093 
  2094 * proper spacing of consecutive markup elements, especially text
  2095 blocks after section headings;
  2096 
  2097 * support bold style (for single symbols only), input syntax is like
  2098 this: "\<^bold>\<alpha>" or "\<^bold>A";
  2099 
  2100 * \<bullet> is now output as bold \cdot by default, which looks much
  2101 better in printed text;
  2102 
  2103 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
  2104 note that these symbols are currently unavailable in Proof General /
  2105 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
  2106 
  2107 * isatool latex no longer depends on changed TEXINPUTS, instead
  2108 isatool document copies the Isabelle style files to the target
  2109 location;
  2110 
  2111 
  2112 *** Isar ***
  2113 
  2114 * Pure/Provers: improved proof by cases and induction;
  2115   - 'case' command admits impromptu naming of parameters (such as
  2116     "case (Suc n)");
  2117   - 'induct' method divinates rule instantiation from the inductive
  2118     claim; no longer requires excessive ?P bindings for proper
  2119     instantiation of cases;
  2120   - 'induct' method properly enumerates all possibilities of set/type
  2121     rules; as a consequence facts may be also passed through *type*
  2122     rules without further ado;
  2123   - 'induct' method now derives symbolic cases from the *rulified*
  2124     rule (before it used to rulify cases stemming from the internal
  2125     atomized version); this means that the context of a non-atomic
  2126     statement becomes is included in the hypothesis, avoiding the
  2127     slightly cumbersome show "PROP ?case" form;
  2128   - 'induct' may now use elim-style induction rules without chaining
  2129     facts, using ``missing'' premises from the goal state; this allows
  2130     rules stemming from inductive sets to be applied in unstructured
  2131     scripts, while still benefitting from proper handling of non-atomic
  2132     statements; NB: major inductive premises need to be put first, all
  2133     the rest of the goal is passed through the induction;
  2134   - 'induct' proper support for mutual induction involving non-atomic
  2135     rule statements (uses the new concept of simultaneous goals, see
  2136     below);
  2137   - append all possible rule selections, but only use the first
  2138     success (no backtracking);
  2139   - removed obsolete "(simplified)" and "(stripped)" options of methods;
  2140   - undeclared rule case names default to numbers 1, 2, 3, ...;
  2141   - added 'print_induct_rules' (covered by help item in recent Proof
  2142     General versions);
  2143   - moved induct/cases attributes to Pure, methods to Provers;
  2144   - generic method setup instantiated for FOL and HOL;
  2145 
  2146 * Pure: support multiple simultaneous goal statements, for example
  2147 "have a: A and b: B" (same for 'theorem' etc.); being a pure
  2148 meta-level mechanism, this acts as if several individual goals had
  2149 been stated separately; in particular common proof methods need to be
  2150 repeated in order to cover all claims; note that a single elimination
  2151 step is *not* sufficient to establish the two conjunctions, so this
  2152 fails:
  2153 
  2154   assume "A & B" then have A and B ..   (*".." fails*)
  2155 
  2156 better use "obtain" in situations as above; alternative refer to
  2157 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
  2158 
  2159 * Pure: proper integration with ``locales''; unlike the original
  2160 version by Florian Kammller, Isar locales package high-level proof
  2161 contexts rather than raw logical ones (e.g. we admit to include
  2162 attributes everywhere); operations on locales include merge and
  2163 rename; support for implicit arguments (``structures''); simultaneous
  2164 type-inference over imports and text; see also HOL/ex/Locales.thy for
  2165 some examples;
  2166 
  2167 * Pure: the following commands have been ``localized'', supporting a
  2168 target locale specification "(in name)": 'lemma', 'theorem',
  2169 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
  2170 stored both within the locale and at the theory level (exported and
  2171 qualified by the locale name);
  2172 
  2173 * Pure: theory goals may now be specified in ``long'' form, with
  2174 ad-hoc contexts consisting of arbitrary locale elements. for example
  2175 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
  2176 definitions may be given, too); the result is a meta-level rule with
  2177 the context elements being discharged in the obvious way;
  2178 
  2179 * Pure: new proof command 'using' allows to augment currently used
  2180 facts after a goal statement ('using' is syntactically analogous to
  2181 'apply', but acts on the goal's facts only); this allows chained facts
  2182 to be separated into parts given before and after a claim, as in
  2183 ``from a and b have C using d and e <proof>'';
  2184 
  2185 * Pure: renamed "antecedent" case to "rule_context";
  2186 
  2187 * Pure: new 'judgment' command records explicit information about the
  2188 object-logic embedding (used by several tools internally); no longer
  2189 use hard-wired "Trueprop";
  2190 
  2191 * Pure: added 'corollary' command;
  2192 
  2193 * Pure: fixed 'token_translation' command;
  2194 
  2195 * Pure: removed obsolete 'exported' attribute;
  2196 
  2197 * Pure: dummy pattern "_" in is/let is now automatically lifted over
  2198 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
  2199 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
  2200 
  2201 * Pure: method 'atomize' presents local goal premises as object-level
  2202 statements (atomic meta-level propositions); setup controlled via
  2203 rewrite rules declarations of 'atomize' attribute; example
  2204 application: 'induct' method with proper rule statements in improper
  2205 proof *scripts*;
  2206 
  2207 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
  2208 now consider the syntactic context of assumptions, giving a better
  2209 chance to get type-inference of the arguments right (this is
  2210 especially important for locales);
  2211 
  2212 * Pure: "sorry" no longer requires quick_and_dirty in interactive
  2213 mode;
  2214 
  2215 * Pure/obtain: the formal conclusion "thesis", being marked as
  2216 ``internal'', may no longer be reference directly in the text;
  2217 potential INCOMPATIBILITY, may need to use "?thesis" in rare
  2218 situations;
  2219 
  2220 * Pure: generic 'sym' attribute which declares a rule both as pure
  2221 'elim?' and for the 'symmetric' operation;
  2222 
  2223 * Pure: marginal comments ``--'' may now occur just anywhere in the
  2224 text; the fixed correlation with particular command syntax has been
  2225 discontinued;
  2226 
  2227 * Pure: new method 'rules' is particularly well-suited for proof
  2228 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
  2229 but often produces more compact proof terms with less detours;
  2230 
  2231 * Pure/Provers/classical: simplified integration with pure rule
  2232 attributes and methods; the classical "intro?/elim?/dest?"
  2233 declarations coincide with the pure ones; the "rule" method no longer
  2234 includes classically swapped intros; "intro" and "elim" methods no
  2235 longer pick rules from the context; also got rid of ML declarations
  2236 AddXIs/AddXEs/AddXDs; all of this has some potential for
  2237 INCOMPATIBILITY;
  2238 
  2239 * Provers/classical: attribute 'swapped' produces classical inversions
  2240 of introduction rules;
  2241 
  2242 * Provers/simplifier: 'simplified' attribute may refer to explicit
  2243 rules instead of full simplifier context; 'iff' attribute handles
  2244 conditional rules;
  2245 
  2246 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
  2247 
  2248 * HOL: 'recdef' now fails on unfinished automated proofs, use
  2249 "(permissive)" option to recover old behavior;
  2250 
  2251 * HOL: 'inductive' no longer features separate (collective) attributes
  2252 for 'intros' (was found too confusing);
  2253 
  2254 * HOL: properly declared induction rules less_induct and
  2255 wf_induct_rule;
  2256 
  2257 
  2258 *** HOL ***
  2259 
  2260 * HOL: moved over to sane numeral syntax; the new policy is as
  2261 follows:
  2262 
  2263   - 0 and 1 are polymorphic constants, which are defined on any
  2264   numeric type (nat, int, real etc.);
  2265 
  2266   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
  2267   binary representation internally;
  2268 
  2269   - type nat has special constructor Suc, and generally prefers Suc 0
  2270   over 1::nat and Suc (Suc 0) over 2::nat;
  2271 
  2272 This change may cause significant problems of INCOMPATIBILITY; here
  2273 are some hints on converting existing sources:
  2274 
  2275   - due to the new "num" token, "-0" and "-1" etc. are now atomic
  2276   entities, so expressions involving "-" (unary or binary minus) need
  2277   to be spaced properly;
  2278 
  2279   - existing occurrences of "1" may need to be constraint "1::nat" or
  2280   even replaced by Suc 0; similar for old "2";
  2281 
  2282   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
  2283 
  2284   - remove all special provisions on numerals in proofs;
  2285 
  2286 * HOL: simp rules nat_number expand numerals on nat to Suc/0
  2287 representation (depends on bin_arith_simps in the default context);
  2288 
  2289 * HOL: symbolic syntax for x^2 (numeral 2);
  2290 
  2291 * HOL: the class of all HOL types is now called "type" rather than
  2292 "term"; INCOMPATIBILITY, need to adapt references to this type class
  2293 in axclass/classes, instance/arities, and (usually rare) occurrences
  2294 in typings (of consts etc.); internally the class is called
  2295 "HOL.type", ML programs should refer to HOLogic.typeS;
  2296 
  2297 * HOL/record package improvements:
  2298   - new derived operations "fields" to build a partial record section,
  2299     "extend" to promote a fixed record to a record scheme, and
  2300     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
  2301     declared as simp by default;
  2302   - shared operations ("more", "fields", etc.) now need to be always
  2303     qualified) --- potential INCOMPATIBILITY;
  2304   - removed "make_scheme" operations (use "make" with "extend") --
  2305     INCOMPATIBILITY;
  2306   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
  2307   - provides cases/induct rules for use with corresponding Isar
  2308     methods (for concrete records, record schemes, concrete more
  2309     parts, and schematic more parts -- in that order);
  2310   - internal definitions directly based on a light-weight abstract
  2311     theory of product types over typedef rather than datatype;
  2312 
  2313 * HOL: generic code generator for generating executable ML code from
  2314 specifications; specific support for HOL constructs such as inductive
  2315 datatypes and sets, as well as recursive functions; can be invoked
  2316 via 'generate_code' theory section;
  2317 
  2318 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
  2319 
  2320 * HOL: consolidated and renamed several theories.  In particular:
  2321         Ord.thy has been absorbed into HOL.thy
  2322         String.thy has been absorbed into List.thy
  2323 
  2324 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
  2325 (beware of argument permutation!);
  2326 
  2327 * HOL: linorder_less_split superseded by linorder_cases;
  2328 
  2329 * HOL/List: "nodups" renamed to "distinct";
  2330 
  2331 * HOL: added "The" definite description operator; move Hilbert's "Eps"
  2332 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
  2333   - Ex_def has changed, now need to use some_eq_ex
  2334 
  2335 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
  2336 in this (rare) case use:
  2337 
  2338   delSWrapper "split_all_tac"
  2339   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
  2340 
  2341 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
  2342 MAY FAIL;
  2343 
  2344 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
  2345 Isabelle's type classes, ^ on functions and relations has too general
  2346 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
  2347 necessary to attach explicit type constraints;
  2348 
  2349 * HOL/Relation: the prefix name of the infix "O" has been changed from
  2350 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
  2351 renamed accordingly (eg "compI" -> "rel_compI").
  2352 
  2353 * HOL: syntax translations now work properly with numerals and records
  2354 expressions;
  2355 
  2356 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
  2357 of "lam" -- INCOMPATIBILITY;
  2358 
  2359 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
  2360 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
  2361 renamed "Product_Type.unit";
  2362 
  2363 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
  2364 
  2365 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
  2366 the "cases" method);
  2367 
  2368 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
  2369 Florian Kammller);
  2370 
  2371 * HOL/IMP: updated and converted to new-style theory format; several
  2372 parts turned into readable document, with proper Isar proof texts and
  2373 some explanations (by Gerwin Klein);
  2374 
  2375 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
  2376 
  2377 * HOL-Hyperreal is now a logic image;
  2378 
  2379 
  2380 *** HOLCF ***
  2381 
  2382 * Isar: consts/constdefs supports mixfix syntax for continuous
  2383 operations;
  2384 
  2385 * Isar: domain package adapted to new-style theory format, e.g. see
  2386 HOLCF/ex/Dnat.thy;
  2387 
  2388 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
  2389 potential INCOMPATIBILITY; now use plain induct_tac instead of former
  2390 lift.induct_tac, always use UU instead of Undef;
  2391 
  2392 * HOLCF/IMP: updated and converted to new-style theory;
  2393 
  2394 
  2395 *** ZF ***
  2396 
  2397 * Isar: proper integration of logic-specific tools and packages,
  2398 including theory commands '(co)inductive', '(co)datatype',
  2399 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
  2400 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
  2401 
  2402 * theory Main no longer includes AC; for the Axiom of Choice, base
  2403 your theory on Main_ZFC;
  2404 
  2405 * the integer library now covers quotients and remainders, with many
  2406 laws relating division to addition, multiplication, etc.;
  2407 
  2408 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
  2409 typeless version of the formalism;
  2410 
  2411 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
  2412 format;
  2413 
  2414 * ZF/Induct: new directory for examples of inductive definitions,
  2415 including theory Multiset for multiset orderings; converted to
  2416 new-style theory format;
  2417 
  2418 * ZF: many new theorems about lists, ordinals, etc.;
  2419 
  2420 
  2421 *** General ***
  2422 
  2423 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
  2424 variable proof controls level of detail: 0 = no proofs (only oracle
  2425 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
  2426 also ref manual for further ML interfaces;
  2427 
  2428 * Pure/axclass: removed obsolete ML interface
  2429 goal_subclass/goal_arity;
  2430 
  2431 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
  2432 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
  2433 separate tokens, so expressions involving minus need to be spaced
  2434 properly;
  2435 
  2436 * Pure/syntax: support non-oriented infixes, using keyword "infix"
  2437 rather than "infixl" or "infixr";
  2438 
  2439 * Pure/syntax: concrete syntax for dummy type variables admits genuine
  2440 sort constraint specifications in type inference; e.g. "x::_::foo"
  2441 ensures that the type of "x" is of sort "foo" (but not necessarily a
  2442 type variable);
  2443 
  2444 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
  2445 control output of nested => (types); the default behavior is
  2446 "type_brackets";
  2447 
  2448 * Pure/syntax: builtin parse translation for "_constify" turns valued
  2449 tokens into AST constants;
  2450 
  2451 * Pure/syntax: prefer later declarations of translations and print
  2452 translation functions; potential INCOMPATIBILITY: need to reverse
  2453 multiple declarations for same syntax element constant;
  2454 
  2455 * Pure/show_hyps reset by default (in accordance to existing Isar
  2456 practice);
  2457 
  2458 * Provers/classical: renamed addaltern to addafter, addSaltern to
  2459 addSafter;
  2460 
  2461 * Provers/clasimp: ``iff'' declarations now handle conditional rules
  2462 as well;
  2463 
  2464 * system: tested support for MacOS X; should be able to get Isabelle +
  2465 Proof General to work in a plain Terminal after installing Poly/ML
  2466 (e.g. from the Isabelle distribution area) and GNU bash alone
  2467 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
  2468 support requires further installations, e.g. from
  2469 http://fink.sourceforge.net/);
  2470 
  2471 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
  2472 
  2473 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
  2474 of 40 MB), cf. ML_OPTIONS;
  2475 
  2476 * system: Proof General keywords specification is now part of the
  2477 Isabelle distribution (see etc/isar-keywords.el);
  2478 
  2479 * system: support for persistent Proof General sessions (refrain from
  2480 outdating all loaded theories on startup); user may create writable
  2481 logic images like this: ``isabelle -q HOL Test'';
  2482 
  2483 * system: smart selection of Isabelle process versus Isabelle
  2484 interface, accommodates case-insensitive file systems (e.g. HFS+); may
  2485 run both "isabelle" and "Isabelle" even if file names are badly
  2486 damaged (executable inspects the case of the first letter of its own
  2487 name); added separate "isabelle-process" and "isabelle-interface";
  2488 
  2489 * system: refrain from any attempt at filtering input streams; no
  2490 longer support ``8bit'' encoding of old isabelle font, instead proper
  2491 iso-latin characters may now be used; the related isatools
  2492 "symbolinput" and "nonascii" have disappeared as well;
  2493 
  2494 * system: removed old "xterm" interface (the print modes "xterm" and
  2495 "xterm_color" are still available for direct use in a suitable
  2496 terminal);
  2497 
  2498 
  2499 
  2500 New in Isabelle99-2 (February 2001)
  2501 -----------------------------------
  2502 
  2503 *** Overview of INCOMPATIBILITIES ***
  2504 
  2505 * HOL: please note that theories in the Library and elsewhere often use the
  2506 new-style (Isar) format; to refer to their theorems in an ML script you must
  2507 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
  2508 
  2509 * HOL: inductive package no longer splits induction rule aggressively,
  2510 but only as far as specified by the introductions given; the old
  2511 format may be recovered via ML function complete_split_rule or attribute
  2512 'split_rule (complete)';
  2513 
  2514 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
  2515 gfp_Tarski to gfp_unfold;
  2516 
  2517 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
  2518 
  2519 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
  2520 relation); infix "^^" has been renamed "``"; infix "``" has been
  2521 renamed "`"; "univalent" has been renamed "single_valued";
  2522 
  2523 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
  2524 operation;
  2525 
  2526 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
  2527 
  2528 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
  2529 
  2530 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
  2531 consequence, it is no longer monotonic wrt. the local goal context
  2532 (which is now passed through the inductive cases);
  2533 
  2534 * Document preparation: renamed standard symbols \<ll> to \<lless> and
  2535 \<gg> to \<ggreater>;
  2536 
  2537 
  2538 *** Document preparation ***
  2539 
  2540 * \isabellestyle{NAME} selects version of Isabelle output (currently
  2541 available: are "it" for near math-mode best-style output, "sl" for
  2542 slanted text style, and "tt" for plain type-writer; if no
  2543 \isabellestyle command is given, output is according to slanted
  2544 type-writer);
  2545 
  2546 * support sub/super scripts (for single symbols only), input syntax is
  2547 like this: "A\<^sup>*" or "A\<^sup>\<star>";
  2548 
  2549 * some more standard symbols; see Appendix A of the system manual for
  2550 the complete list of symbols defined in isabellesym.sty;
  2551 
  2552 * improved isabelle style files; more abstract symbol implementation
  2553 (should now use \isamath{...} and \isatext{...} in custom symbol
  2554 definitions);
  2555 
  2556 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
  2557 state; Note that presentation of goal states does not conform to
  2558 actual human-readable proof documents.  Please do not include goal
  2559 states into document output unless you really know what you are doing!
  2560 
  2561 * proper indentation of antiquoted output with proportional LaTeX
  2562 fonts;
  2563 
  2564 * no_document ML operator temporarily disables LaTeX document
  2565 generation;
  2566 
  2567 * isatool unsymbolize tunes sources for plain ASCII communication;
  2568 
  2569 
  2570 *** Isar ***
  2571 
  2572 * Pure: Isar now suffers initial goal statements to contain unbound
  2573 schematic variables (this does not conform to actual readable proof
  2574 documents, due to unpredictable outcome and non-compositional proof
  2575 checking); users who know what they are doing may use schematic goals
  2576 for Prolog-style synthesis of proven results;
  2577 
  2578 * Pure: assumption method (an implicit finishing) now handles actual
  2579 rules as well;
  2580 
  2581 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
  2582 initial goal, declare "that" only as Pure intro (only for single
  2583 steps); the "that" rule assumption may now be involved in implicit
  2584 finishing, thus ".." becomes a feasible for trivial obtains;
  2585 
  2586 * Pure: default proof step now includes 'intro_classes'; thus trivial
  2587 instance proofs may be performed by "..";
  2588 
  2589 * Pure: ?thesis / ?this / "..." now work for pure meta-level
  2590 statements as well;
  2591 
  2592 * Pure: more robust selection of calculational rules;
  2593 
  2594 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
  2595 rule (as well as the assumption rule);
  2596 
  2597 * Pure: 'thm_deps' command visualizes dependencies of theorems and
  2598 lemmas, using the graph browser tool;
  2599 
  2600 * Pure: predict failure of "show" in interactive mode;
  2601 
  2602 * Pure: 'thms_containing' now takes actual terms as arguments;
  2603 
  2604 * HOL: improved method 'induct' --- now handles non-atomic goals
  2605 (potential INCOMPATIBILITY); tuned error handling;
  2606 
  2607 * HOL: cases and induct rules now provide explicit hints about the
  2608 number of facts to be consumed (0 for "type" and 1 for "set" rules);
  2609 any remaining facts are inserted into the goal verbatim;
  2610 
  2611 * HOL: local contexts (aka cases) may now contain term bindings as
  2612 well; the 'cases' and 'induct' methods new provide a ?case binding for
  2613 the result to be shown in each case;
  2614 
  2615 * HOL: added 'recdef_tc' command;
  2616 
  2617 * isatool convert assists in eliminating legacy ML scripts;
  2618 
  2619 
  2620 *** HOL ***
  2621 
  2622 * HOL/Library: a collection of generic theories to be used together
  2623 with main HOL; the theory loader path already includes this directory
  2624 by default; the following existing theories have been moved here:
  2625 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
  2626 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
  2627 
  2628 * HOL/Unix: "Some aspects of Unix file-system security", a typical
  2629 modelling and verification task performed in Isabelle/HOL +
  2630 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
  2631 
  2632 * HOL/Algebra: special summation operator SUM no longer exists, it has
  2633 been replaced by setsum; infix 'assoc' now has priority 50 (like
  2634 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
  2635 'domain', this makes the theory consistent with mathematical
  2636 literature;
  2637 
  2638 * HOL basics: added overloaded operations "inverse" and "divide"
  2639 (infix "/"), syntax for generic "abs" operation, generic summation
  2640 operator \<Sum>;
  2641 
  2642 * HOL/typedef: simplified package, provide more useful rules (see also
  2643 HOL/subset.thy);
  2644 
  2645 * HOL/datatype: induction rule for arbitrarily branching datatypes is
  2646 now expressed as a proper nested rule (old-style tactic scripts may
  2647 require atomize_strip_tac to cope with non-atomic premises);
  2648 
  2649 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
  2650 to "split_conv" (old name still available for compatibility);
  2651 
  2652 * HOL: improved concrete syntax for strings (e.g. allows translation
  2653 rules with string literals);
  2654 
  2655 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
  2656  and Fleuriot's mechanization of analysis, including the transcendental
  2657  functions for the reals;
  2658 
  2659 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
  2660 
  2661 
  2662 *** CTT ***
  2663 
  2664 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
  2665 "lam" is displayed as TWO lambda-symbols
  2666 
  2667 * CTT: theory Main now available, containing everything (that is, Bool
  2668 and Arith);
  2669 
  2670 
  2671 *** General ***
  2672 
  2673 * Pure: the Simplifier has been implemented properly as a derived rule
  2674 outside of the actual kernel (at last!); the overall performance
  2675 penalty in practical applications is about 50%, while reliability of
  2676 the Isabelle inference kernel has been greatly improved;
  2677 
  2678 * print modes "brackets" and "no_brackets" control output of nested =>
  2679 (types) and ==> (props); the default behaviour is "brackets";
  2680 
  2681 * Provers: fast_tac (and friends) now handle actual object-logic rules
  2682 as assumptions as well;
  2683 
  2684 * system: support Poly/ML 4.0;
  2685 
  2686 * system: isatool install handles KDE version 1 or 2;
  2687 
  2688 
  2689 
  2690 New in Isabelle99-1 (October 2000)
  2691 ----------------------------------
  2692 
  2693 *** Overview of INCOMPATIBILITIES ***
  2694 
  2695 * HOL: simplification of natural numbers is much changed; to partly
  2696 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
  2697 issue the following ML commands:
  2698 
  2699   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
  2700   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
  2701 
  2702 * HOL: simplification no longer dives into case-expressions; this is
  2703 controlled by "t.weak_case_cong" for each datatype t;
  2704 
  2705 * HOL: nat_less_induct renamed to less_induct;
  2706 
  2707 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
  2708 fixsome to patch .thy and .ML sources automatically;
  2709 
  2710   select_equality  -> some_equality
  2711   select_eq_Ex     -> some_eq_ex
  2712   selectI2EX       -> someI2_ex
  2713   selectI2         -> someI2
  2714   selectI          -> someI
  2715   select1_equality -> some1_equality
  2716   Eps_sym_eq       -> some_sym_eq_trivial
  2717   Eps_eq           -> some_eq_trivial
  2718 
  2719 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
  2720 
  2721 * HOL: removed obsolete theorem binding expand_if (refer to split_if
  2722 instead);
  2723 
  2724 * HOL: the recursion equations generated by 'recdef' are now called
  2725 f.simps instead of f.rules;
  2726 
  2727 * HOL: qed_spec_mp now also handles bounded ALL as well;
  2728 
  2729 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  2730 sometimes be needed;
  2731 
  2732 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  2733 
  2734 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  2735 
  2736 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  2737 product is now "<*>" instead of "Times"; the lexicographic product is
  2738 now "<*lex*>" instead of "**";
  2739 
  2740 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  2741 of main HOL, but was unused); better use HOL's datatype package;
  2742 
  2743 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  2744 the old syntax may be recovered as follows:
  2745 
  2746   syntax (symbols)
  2747     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  2748       (infixl "\\<oplus>" 100)
  2749 
  2750 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  2751 
  2752 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  2753 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  2754 internally;
  2755 
  2756 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  2757 changed from A/r to A//r;
  2758 
  2759 * ZF: new treatment of arithmetic (nat & int) may break some old
  2760 proofs;
  2761 
  2762 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  2763 rulify -> rule_format, elimify -> elim_format, ...);
  2764 
  2765 * Isar/Provers: intro/elim/dest attributes changed; renamed
  2766 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  2767 should have to change intro!! to intro? only); replaced "delrule" by
  2768 "rule del";
  2769 
  2770 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  2771 
  2772 * Provers: strengthened force_tac by using new first_best_tac;
  2773 
  2774 * LaTeX document preparation: several changes of isabelle.sty (see
  2775 lib/texinputs);
  2776 
  2777 
  2778 *** Document preparation ***
  2779 
  2780 * formal comments (text blocks etc.) in new-style theories may now
  2781 contain antiquotations of thm/prop/term/typ/text to be presented
  2782 according to latex print mode; concrete syntax is like this:
  2783 @{term[show_types] "f(x) = a + x"};
  2784 
  2785 * isatool mkdir provides easy setup of Isabelle session directories,
  2786 including proper document sources;
  2787 
  2788 * generated LaTeX sources are now deleted after successful run
  2789 (isatool document -c); may retain a copy somewhere else via -D option
  2790 of isatool usedir;
  2791 
  2792 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  2793 style files, achieving self-contained LaTeX sources and simplifying
  2794 LaTeX debugging;
  2795 
  2796 * old-style theories now produce (crude) LaTeX output as well;
  2797 
  2798 * browser info session directories are now self-contained (may be put
  2799 on WWW server seperately); improved graphs of nested sessions; removed
  2800 graph for 'all sessions';
  2801 
  2802 * several improvements in isabelle style files; \isabellestyle{it}
  2803 produces fake math mode output; \isamarkupheader is now \section by
  2804 default; see lib/texinputs/isabelle.sty etc.;
  2805 
  2806 
  2807 *** Isar ***
  2808 
  2809 * Isar/Pure: local results and corresponding term bindings are now
  2810 subject to Hindley-Milner polymorphism (similar to ML); this
  2811 accommodates incremental type-inference very nicely;
  2812 
  2813 * Isar/Pure: new derived language element 'obtain' supports
  2814 generalized existence reasoning;
  2815 
  2816 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  2817 support accumulation of results, without applying any rules yet;
  2818 useful to collect intermediate results without explicit name
  2819 references, and for use with transitivity rules with more than 2
  2820 premises;
  2821 
  2822 * Isar/Pure: scalable support for case-analysis type proofs: new
  2823 'case' language element refers to local contexts symbolically, as
  2824 produced by certain proof methods; internally, case names are attached
  2825 to theorems as "tags";
  2826 
  2827 * Isar/Pure: theory command 'hide' removes declarations from
  2828 class/type/const name spaces;
  2829 
  2830 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  2831 indicate potential overloading;
  2832 
  2833 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  2834 
  2835 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  2836 "{a,b,c}" instead of {a,b,c};
  2837 
  2838 * Isar/Pure now provides its own version of intro/elim/dest
  2839 attributes; useful for building new logics, but beware of confusion
  2840 with the version in Provers/classical;
  2841 
  2842 * Isar/Pure: the local context of (non-atomic) goals is provided via
  2843 case name 'antecedent';
  2844 
  2845 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  2846 to the current context is now done automatically);
  2847 
  2848 * Isar/Pure: theory command 'method_setup' provides a simple interface
  2849 for definining proof methods in ML;
  2850 
  2851 * Isar/Provers: intro/elim/dest attributes changed; renamed
  2852 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  2853 most cases, one should have to change intro!! to intro? only);
  2854 replaced "delrule" by "rule del";
  2855 
  2856 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  2857 'symmetric' attribute (the latter supercedes [RS sym]);
  2858 
  2859 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  2860 method modifier); 'simp' method: 'only:' modifier removes loopers as
  2861 well (including splits);
  2862 
  2863 * Isar/Provers: Simplifier and Classical methods now support all kind
  2864 of modifiers used in the past, including 'cong', 'iff', etc.
  2865 
  2866 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  2867 of Simplifier and Classical reasoner);
  2868 
  2869 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  2870 now support named cases; major packages (inductive, datatype, primrec,
  2871 recdef) support case names and properly name parameters;
  2872 
  2873 * Isar/HOL: new transitivity rules for substitution in inequalities --
  2874 monotonicity conditions are extracted to be proven at end of
  2875 calculations;
  2876 
  2877 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  2878 method anyway;
  2879 
  2880 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  2881 split_if split_if_asm; datatype package provides theorems foo.splits =
  2882 foo.split foo.split_asm for each datatype;
  2883 
  2884 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  2885 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  2886 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  2887 use "(cases (simplified))" method in proper proof texts);
  2888 
  2889 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  2890 
  2891 * Isar: names of theorems etc. may be natural numbers as well;
  2892 
  2893 * Isar: 'pr' command: optional arguments for goals_limit and
  2894 ProofContext.prems_limit; no longer prints theory contexts, but only
  2895 proof states;
  2896 
  2897 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  2898 additional print modes to be specified; e.g. "pr(latex)" will print
  2899 proof state according to the Isabelle LaTeX style;
  2900 
  2901 * Isar: improved support for emulating tactic scripts, including proof
  2902 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  2903 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  2904 (for HOL datatypes);
  2905 
  2906 * Isar: simplified (more robust) goal selection of proof methods: 1st
  2907 goal, all goals, or explicit goal specifier (tactic emulation); thus
  2908 'proof method scripts' have to be in depth-first order;
  2909 
  2910 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  2911 
  2912 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  2913 should instead use individual commands for printing items
  2914 (print_commands, print_methods etc.);
  2915 
  2916 * Isar: added 'nothing' --- the empty list of theorems;
  2917 
  2918 
  2919 *** HOL ***
  2920 
  2921 * HOL/MicroJava: formalization of a fragment of Java, together with a
  2922 corresponding virtual machine and a specification of its bytecode
  2923 verifier and a lightweight bytecode verifier, including proofs of
  2924 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  2925 Cornelia Pusch (see also the homepage of project Bali at
  2926 http://isabelle.in.tum.de/Bali/);
  2927 
  2928 * HOL/Algebra: new theory of rings and univariate polynomials, by
  2929 Clemens Ballarin;
  2930 
  2931 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  2932 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  2933 Rasmussen;
  2934 
  2935 * HOL/Lattice: fundamental concepts of lattice theory and order
  2936 structures, including duals, properties of bounds versus algebraic
  2937 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  2938 Theorem for complete lattices etc.; may also serve as a demonstration
  2939 for abstract algebraic reasoning using axiomatic type classes, and
  2940 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  2941 
  2942 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  2943 von Oheimb;
  2944 
  2945 * HOL/IMPP: extension of IMP with local variables and mutually
  2946 recursive procedures, by David von Oheimb;
  2947 
  2948 * HOL/Lambda: converted into new-style theory and document;
  2949 
  2950 * HOL/ex/Multiquote: example of multiple nested quotations and
  2951 anti-quotations -- basically a generalized version of de-Bruijn
  2952 representation; very useful in avoiding lifting of operations;
  2953 
  2954 * HOL/record: added general record equality rule to simpset; fixed
  2955 select-update simplification procedure to handle extended records as
  2956 well; admit "r" as field name;
  2957 
  2958 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  2959 other numeric types and also as the identity of groups, rings, etc.;
  2960 
  2961 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  2962 Types nat and int belong to this axclass;
  2963 
  2964 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  2965    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  2966    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  2967   two terms #m*u and #n*u are replaced by #(m+n)*u
  2968     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  2969   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  2970     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  2971 
  2972 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  2973 powerful prover for predicate logic but knows nothing of clasets; see
  2974 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  2975 
  2976 * HOL: new version of "case_tac" subsumes both boolean case split and
  2977 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  2978 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  2979 
  2980 * HOL: simplification no longer dives into case-expressions: only the
  2981 selector expression is simplified, but not the remaining arms; to
  2982 enable full simplification of case-expressions for datatype t, you may
  2983 remove t.weak_case_cong from the simpset, either globally (Delcongs
  2984 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  2985 
  2986 * HOL/recdef: the recursion equations generated by 'recdef' for
  2987 function 'f' are now called f.simps instead of f.rules; if all
  2988 termination conditions are proved automatically, these simplification
  2989 rules are added to the simpset, as in primrec; rules may be named
  2990 individually as well, resulting in a separate list of theorems for
  2991 each equation;
  2992 
  2993 * HOL/While is a new theory that provides a while-combinator. It
  2994 permits the definition of tail-recursive functions without the
  2995 provision of a termination measure. The latter is necessary once the
  2996 invariant proof rule for while is applied.
  2997 
  2998 * HOL: new (overloaded) notation for the set of elements below/above
  2999 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  3000 
  3001 * HOL: theorems impI, allI, ballI bound as "strip";
  3002 
  3003 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  3004 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  3005 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  3006 
  3007 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  3008 
  3009 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  3010 main HOL, but was unused);
  3011 
  3012 * HOL: fewer consts declared as global (e.g. have to refer to
  3013 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  3014 
  3015 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  3016 in case of overlap with user translations (e.g. judgements over
  3017 tuples); (note that the underlying logical represenation is still
  3018 bogus);
  3019 
  3020 
  3021 *** ZF ***
  3022 
  3023 * ZF: simplification automatically cancels common terms in arithmetic
  3024 expressions over nat and int;
  3025 
  3026 * ZF: new treatment of nat to minimize type-checking: all operators
  3027 coerce their operands to a natural number using the function natify,
  3028 making the algebraic laws unconditional;
  3029 
  3030 * ZF: as above, for int: operators coerce their operands to an integer
  3031 using the function intify;
  3032 
  3033 * ZF: the integer library now contains many of the usual laws for the
  3034 orderings, including $<=, and monotonicity laws for $+ and $*;
  3035 
  3036 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  3037 simplification;
  3038 
  3039 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  3040 to the simplifier and classical reasoner simultaneously;
  3041 
  3042 
  3043 *** General ***
  3044 
  3045 * Provers: blast_tac now handles actual object-logic rules as
  3046 assumptions; note that auto_tac uses blast_tac internally as well;
  3047 
  3048 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  3049 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  3050 
  3051 * Provers: delrules now handles destruct rules as well (no longer need
  3052 explicit make_elim);
  3053 
  3054 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  3055   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  3056 use instead the strong form,
  3057   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  3058 in HOL, FOL and ZF the function cla_make_elim will create such rules
  3059 from destruct-rules;
  3060 
  3061 * Provers: Simplifier.easy_setup provides a fast path to basic
  3062 Simplifier setup for new object-logics;
  3063 
  3064 * Pure: AST translation rules no longer require constant head on LHS;
  3065 
  3066 * Pure: improved name spaces: ambiguous output is qualified; support
  3067 for hiding of names;
  3068 
  3069 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  3070 XSYMBOL_HOME; no longer need to do manual configuration in most
  3071 situations;
  3072 
  3073 * system: compression of ML heaps images may now be controlled via -c
  3074 option of isabelle and isatool usedir (currently only observed by
  3075 Poly/ML);
  3076 
  3077 * system: isatool installfonts may handle X-Symbol fonts as well (very
  3078 useful for remote X11);
  3079 
  3080 * system: provide TAGS file for Isabelle sources;
  3081 
  3082 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  3083 order;
  3084 
  3085 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  3086 timing flag supersedes proof_timing and Toplevel.trace;
  3087 
  3088 * ML: new combinators |>> and |>>> for incremental transformations
  3089 with secondary results (e.g. certain theory extensions):
  3090 
  3091 * ML: PureThy.add_defs gets additional argument to indicate potential
  3092 overloading (usually false);
  3093 
  3094 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  3095 results;
  3096 
  3097 
  3098 
  3099 New in Isabelle99 (October 1999)
  3100 --------------------------------
  3101 
  3102 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  3103 
  3104 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  3105 are no longer simplified.  (This allows the simplifier to unfold recursive
  3106 functional programs.)  To restore the old behaviour, declare
  3107 
  3108     Delcongs [if_weak_cong];
  3109 
  3110 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  3111 complement;
  3112 
  3113 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  3114 
  3115 * HOL/datatype: mutual_induct_tac no longer exists --
  3116   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  3117 
  3118 * HOL/typedef: fixed type inference for representing set; type
  3119 arguments now have to occur explicitly on the rhs as type constraints;
  3120 
  3121 * ZF: The con_defs part of an inductive definition may no longer refer
  3122 to constants declared in the same theory;
  3123 
  3124 * HOL, ZF: the function mk_cases, generated by the inductive
  3125 definition package, has lost an argument.  To simplify its result, it
  3126 uses the default simpset instead of a supplied list of theorems.
  3127 
  3128 * HOL/List: the constructors of type list are now Nil and Cons;
  3129 
  3130 * Simplifier: the type of the infix ML functions
  3131         setSSolver addSSolver setSolver addSolver
  3132 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  3133 for packaging solvers. A solver is created via
  3134         mk_solver: string -> (thm list -> int -> tactic) -> solver
  3135 where the string argument is only a comment.
  3136 
  3137 
  3138 *** Proof tools ***
  3139 
  3140 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  3141 decision procedure for linear arithmetic. Currently it is used for
  3142 types `nat', `int', and `real' in HOL (see below); it can, should and
  3143 will be instantiated for other types and logics as well.
  3144 
  3145 * The simplifier now accepts rewrite rules with flexible heads, eg
  3146      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  3147   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  3148   matching.
  3149 
  3150 
  3151 *** General ***
  3152 
  3153 * New Isabelle/Isar subsystem provides an alternative to traditional
  3154 tactical theorem proving; together with the ProofGeneral/isar user
  3155 interface it offers an interactive environment for developing human
  3156 readable proof documents (Isar == Intelligible semi-automated
  3157 reasoning); for further information see isatool doc isar-ref,
  3158 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  3159 
  3160 * improved and simplified presentation of theories: better HTML markup
  3161 (including colors), graph views in several sizes; isatool usedir now
  3162 provides a proper interface for user theories (via -P option); actual
  3163 document preparation based on (PDF)LaTeX is available as well (for
  3164 new-style theories only); see isatool doc system for more information;
  3165 
  3166 * native support for Proof General, both for classic Isabelle and
  3167 Isabelle/Isar;
  3168 
  3169 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  3170 using the graph browser tool;
  3171 
  3172 * Isabelle manuals now also available as PDF;
  3173 
  3174 * theory loader rewritten from scratch (may not be fully
  3175 bug-compatible); old loadpath variable has been replaced by show_path,
  3176 add_path, del_path, reset_path functions; new operations such as
  3177 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  3178 isatool doc ref);
  3179 
  3180 * improved isatool install: option -k creates KDE application icon,
  3181 option -p DIR installs standalone binaries;
  3182 
  3183 * added ML_PLATFORM setting (useful for cross-platform installations);
  3184 more robust handling of platform specific ML images for SML/NJ;
  3185 
  3186 * the settings environment is now statically scoped, i.e. it is never
  3187 created again in sub-processes invoked from isabelle, isatool, or
  3188 Isabelle;
  3189 
  3190 * path element specification '~~' refers to '$ISABELLE_HOME';
  3191 
  3192 * in locales, the "assumes" and "defines" parts may be omitted if
  3193 empty;
  3194 
  3195 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  3196 long arrows);
  3197 
  3198 * new print_mode "HTML";
  3199 
  3200 * new flag show_tags controls display of tags of theorems (which are
  3201 basically just comments that may be attached by some tools);
  3202 
  3203 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  3204 mode and goal output format:
  3205 
  3206 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  3207 244c244
  3208 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  3209 ---
  3210 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  3211 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  3212 181c181
  3213 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  3214 ---
  3215 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  3216 
  3217 * function bind_thms stores lists of theorems (cf. bind_thm);
  3218 
  3219 * new shorthand tactics ftac, eatac, datac, fatac;
  3220 
  3221 * qed (and friends) now accept "" as result name; in that case the
  3222 theorem is not stored, but proper checks and presentation of the
  3223 result still apply;
  3224 
  3225 * theorem database now also indexes constants "Trueprop", "all",
  3226 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  3227 
  3228 
  3229 *** HOL ***
  3230 
  3231 ** HOL arithmetic **
  3232 
  3233 * There are now decision procedures for linear arithmetic over nat and
  3234 int:
  3235 
  3236 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  3237 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  3238 are treated as atomic; subformulae not involving type `nat' or `int'
  3239 are ignored; quantified subformulae are ignored unless they are
  3240 positive universal or negative existential. The tactic has to be
  3241 invoked by hand and can be a little bit slow. In particular, the
  3242 running time is exponential in the number of occurrences of `min' and
  3243 `max', and `-' on `nat'.
  3244 
  3245 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  3246 (negated) (in)equalities among the premises and the conclusion into
  3247 account (i.e. no compound formulae) and does not know about `min' and
  3248 `max', and `-' on `nat'. It is fast and is used automatically by the
  3249 simplifier.
  3250 
  3251 NB: At the moment, these decision procedures do not cope with mixed
  3252 nat/int formulae where the two parts interact, such as `m < n ==>
  3253 int(m) < int(n)'.
  3254 
  3255 * HOL/Numeral provides a generic theory of numerals (encoded
  3256 efficiently as bit strings); setup for types nat/int/real is in place;
  3257 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  3258 int, existing theories and proof scripts may require a few additional
  3259 type constraints;
  3260 
  3261 * integer division and remainder can now be performed on constant
  3262 arguments;
  3263 
  3264 * many properties of integer multiplication, division and remainder
  3265 are now available;
  3266 
  3267 * An interface to the Stanford Validity Checker (SVC) is available through the
  3268 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  3269 are proved automatically.  SVC must be installed separately, and its results
  3270 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  3271 invocation of the underlying oracle).  For SVC see
  3272   http://verify.stanford.edu/SVC
  3273 
  3274 * IsaMakefile: the HOL-Real target now builds an actual image;
  3275 
  3276 
  3277 ** HOL misc **
  3278 
  3279 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  3280 (in Isabelle/Isar) -- by Gertrud Bauer;
  3281 
  3282 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  3283 analysis for assembly languages with subtypes;
  3284 
  3285 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  3286 -- avoids syntactic ambiguities and treats state, transition, and
  3287 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  3288 changed syntax and (many) tactics;
  3289 
  3290 * HOL/inductive: Now also handles more general introduction rules such
  3291   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  3292   theorems are now maintained within the theory (maintained via the
  3293   "mono" attribute);
  3294 
  3295 * HOL/datatype: Now also handles arbitrarily branching datatypes
  3296   (using function types) such as
  3297 
  3298   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  3299 
  3300 * HOL/record: record_simproc (part of the default simpset) takes care
  3301 of selectors applied to updated records; record_split_tac is no longer
  3302 part of the default claset; update_defs may now be removed from the
  3303 simpset in many cases; COMPATIBILITY: old behavior achieved by
  3304 
  3305   claset_ref () := claset() addSWrapper record_split_wrapper;
  3306   Delsimprocs [record_simproc]
  3307 
  3308 * HOL/typedef: fixed type inference for representing set; type
  3309 arguments now have to occur explicitly on the rhs as type constraints;
  3310 
  3311 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  3312 names rather than an ML expression;
  3313 
  3314 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  3315 supplied later.  Program schemes can be defined, such as
  3316     "While B C s = (if B s then While B C (C s) else s)"
  3317 where the well-founded relation can be chosen after B and C have been given.
  3318 
  3319 * HOL/List: the constructors of type list are now Nil and Cons;
  3320 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  3321 course, ML tools referring to List.list.op # etc. have to be adapted;
  3322 
  3323 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  3324 disabled by default; run isabelle with option -m HOL to get back to
  3325 the original Gordon/HOL-style output;
  3326 
  3327 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  3328 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  3329 
  3330 * HOL basic syntax simplified (more orthogonal): all variants of
  3331 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  3332 Eps operator is provided as well: "SOME x. P[x]";
  3333 
  3334 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  3335 
  3336 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  3337 thus available for user theories;
  3338 
  3339 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  3340 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  3341 time;
  3342 
  3343 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  3344 several times and then mp;
  3345 
  3346 
  3347 *** LK ***
  3348 
  3349 * the notation <<...>> is now available as a notation for sequences of
  3350 formulas;
  3351 
  3352 * the simplifier is now installed
  3353 
  3354 * the axiom system has been generalized (thanks to Soren Heilmann)
  3355 
  3356 * the classical reasoner now has a default rule database
  3357 
  3358 
  3359 *** ZF ***
  3360 
  3361 * new primrec section allows primitive recursive functions to be given
  3362 directly (as in HOL) over datatypes and the natural numbers;
  3363 
  3364 * new tactics induct_tac and exhaust_tac for induction (or case
  3365 analysis) over datatypes and the natural numbers;
  3366 
  3367 * the datatype declaration of type T now defines the recursor T_rec;
  3368 
  3369 * simplification automatically does freeness reasoning for datatype
  3370 constructors;
  3371 
  3372 * automatic type-inference, with AddTCs command to insert new
  3373 type-checking rules;
  3374 
  3375 * datatype introduction rules are now added as Safe Introduction rules
  3376 to the claset;
  3377 
  3378 * the syntax "if P then x else y" is now available in addition to
  3379 if(P,x,y);
  3380 
  3381 
  3382 *** Internal programming interfaces ***
  3383 
  3384 * tuned simplifier trace output; new flag debug_simp;
  3385 
  3386 * structures Vartab / Termtab (instances of TableFun) offer efficient
  3387 tables indexed by indexname_ord / term_ord (compatible with aconv);
  3388 
  3389 * AxClass.axclass_tac lost the theory argument;
  3390 
  3391 * tuned current_goals_markers semantics: begin / end goal avoids
  3392 printing empty lines;
  3393 
  3394 * removed prs and prs_fn hook, which was broken because it did not
  3395 include \n in its semantics, forcing writeln to add one
  3396 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  3397 string -> unit if you really want to output text without newline;
  3398 
  3399 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  3400 plain output, interface builders may have to enable 'isabelle_font'
  3401 mode to get Isabelle font glyphs as before;
  3402 
  3403 * refined token_translation interface; INCOMPATIBILITY: output length
  3404 now of type real instead of int;
  3405 
  3406 * theory loader actions may be traced via new ThyInfo.add_hook
  3407 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  3408 your own database of information attached to *whole* theories -- as
  3409 opposed to intra-theory data slots offered via TheoryDataFun;
  3410 
  3411 * proper handling of dangling sort hypotheses (at last!);
  3412 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  3413 extra sort hypotheses that can be witnessed from the type signature;
  3414 the force_strip_shyps flag is gone, any remaining shyps are simply
  3415 left in the theorem (with a warning issued by strip_shyps_warning);
  3416 
  3417 
  3418 
  3419 New in Isabelle98-1 (October 1998)
  3420 ----------------------------------
  3421 
  3422 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  3423 
  3424 * several changes of automated proof tools;
  3425 
  3426 * HOL: major changes to the inductive and datatype packages, including
  3427 some minor incompatibilities of theory syntax;
  3428 
  3429 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  3430 called `inj_on';
  3431 
  3432 * HOL: removed duplicate thms in Arith:
  3433   less_imp_add_less  should be replaced by  trans_less_add1
  3434   le_imp_add_le      should be replaced by  trans_le_add1
  3435 
  3436 * HOL: unary minus is now overloaded (new type constraints may be
  3437 required);
  3438 
  3439 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  3440 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  3441 now taken as an integer constant.
  3442 
  3443 * Pure: ML function 'theory_of' renamed to 'theory';
  3444 
  3445 
  3446 *** Proof tools ***
  3447 
  3448 * Simplifier:
  3449   1. Asm_full_simp_tac is now more aggressive.
  3450      1. It will sometimes reorient premises if that increases their power to
  3451         simplify.
  3452      2. It does no longer proceed strictly from left to right but may also
  3453         rotate premises to achieve further simplification.
  3454      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  3455      old Asm_full_simp_tac in that it does not rotate premises.
  3456   2. The simplifier now knows a little bit about nat-arithmetic.
  3457 
  3458 * Classical reasoner: wrapper mechanism for the classical reasoner now
  3459 allows for selected deletion of wrappers, by introduction of names for
  3460 wrapper functionals.  This implies that addbefore, addSbefore,
  3461 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  3462 and that adding two tactics with the same name overwrites the first
  3463 one (emitting a warning).
  3464   type wrapper = (int -> tactic) -> (int -> tactic)
  3465   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  3466   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  3467   delWrapper, delSWrapper: claset *  string            -> claset
  3468   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  3469 
  3470 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  3471 semantics; addbefore now affects only the unsafe part of step_tac
  3472 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  3473 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  3474 by Force_tac;
  3475 
  3476 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  3477 compWrapper; added safe wrapper (and access functions for it);
  3478 
  3479 * HOL/split_all_tac is now much faster and fails if there is nothing
  3480 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  3481 and the names of the automatically generated variables have changed.
  3482 split_all_tac has moved within claset() from unsafe wrappers to safe
  3483 wrappers, which means that !!-bound variables are split much more
  3484 aggressively, and safe_tac and clarify_tac now split such variables.
  3485 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  3486 Note: the same holds for record_split_tac, which does the job of
  3487 split_all_tac for record fields.
  3488 
  3489 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  3490 permanently to the default simpset using Addsplits just like
  3491 Addsimps. They can be removed via Delsplits just like
  3492 Delsimps. Lower-case versions are also available.
  3493 
  3494 * HOL/Simplifier: The rule split_if is now part of the default
  3495 simpset. This means that the simplifier will eliminate all occurrences
  3496 of if-then-else in the conclusion of a goal. To prevent this, you can
  3497 either remove split_if completely from the default simpset by
  3498 `Delsplits [split_if]' or remove it in a specific call of the
  3499 simplifier using `... delsplits [split_if]'.  You can also add/delete
  3500 other case splitting rules to/from the default simpset: every datatype
  3501 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  3502 t is the name of the datatype).
  3503 
  3504 * Classical reasoner / Simplifier combination: new force_tac (and
  3505 derivatives Force_tac, force) combines rewriting and classical
  3506 reasoning (and whatever other tools) similarly to auto_tac, but is
  3507 aimed to solve the given subgoal completely.
  3508 
  3509 
  3510 *** General ***
  3511 
  3512 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  3513 and `goalw': the theory is no longer needed as an explicit argument -
  3514 the current theory context is used; assumptions are no longer returned
  3515 at the ML-level unless one of them starts with ==> or !!; it is
  3516 recommended to convert to these new commands using isatool fixgoal
  3517 (backup your sources first!);
  3518 
  3519 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  3520 the current theory context, and 'theory' to lookup stored theories;
  3521 
  3522 * new theory section 'locale' for declaring constants, assumptions and
  3523 definitions that have local scope;
  3524 
  3525 * new theory section 'nonterminals' for purely syntactic types;
  3526 
  3527 * new theory section 'setup' for generic ML setup functions
  3528 (e.g. package initialization);
  3529 
  3530 * the distribution now includes Isabelle icons: see
  3531 lib/logo/isabelle-{small,tiny}.xpm;
  3532 
  3533 * isatool install - install binaries with absolute references to
  3534 ISABELLE_HOME/bin;
  3535 
  3536 * isatool logo -- create instances of the Isabelle logo (as EPS);
  3537 
  3538 * print mode 'emacs' reserved for Isamode;
  3539 
  3540 * support multiple print (ast) translations per constant name;
  3541 
  3542 * theorems involving oracles are now printed with a suffixed [!];
  3543 
  3544 
  3545 *** HOL ***
  3546 
  3547 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  3548 
  3549 * HOL/inductive package reorganized and improved: now supports mutual
  3550 definitions such as
  3551 
  3552   inductive EVEN ODD
  3553     intrs
  3554       null "0 : EVEN"
  3555       oddI "n : EVEN ==> Suc n : ODD"
  3556       evenI "n : ODD ==> Suc n : EVEN"
  3557 
  3558 new theorem list "elims" contains an elimination rule for each of the
  3559 recursive sets; inductive definitions now handle disjunctive premises
  3560 correctly (also ZF);
  3561 
  3562 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  3563 "mutual_induct" no longer exists - the induction rule is always
  3564 contained in "induct";
  3565 
  3566 
  3567 * HOL/datatype package re-implemented and greatly improved: now
  3568 supports mutually recursive datatypes such as
  3569 
  3570   datatype
  3571     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  3572             | SUM ('a aexp) ('a aexp)
  3573             | DIFF ('a aexp) ('a aexp)
  3574             | NUM 'a
  3575   and
  3576     'a bexp = LESS ('a aexp) ('a aexp)
  3577             | AND ('a bexp) ('a bexp)
  3578             | OR ('a bexp) ('a bexp)
  3579 
  3580 as well as indirectly recursive datatypes such as
  3581 
  3582   datatype
  3583     ('a, 'b) term = Var 'a
  3584                   | App 'b ((('a, 'b) term) list)
  3585 
  3586 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  3587 induction on mutually / indirectly recursive datatypes.
  3588 
  3589 Primrec equations are now stored in theory and can be accessed via
  3590 <function_name>.simps.
  3591 
  3592 INCOMPATIBILITIES:
  3593 
  3594   - Theories using datatypes must now have theory Datatype as an
  3595     ancestor.
  3596   - The specific <typename>.induct_tac no longer exists - use the
  3597     generic induct_tac instead.
  3598   - natE has been renamed to nat.exhaust - use exhaust_tac
  3599     instead of res_inst_tac ... natE. Note that the variable
  3600     names in nat.exhaust differ from the names in natE, this
  3601     may cause some "fragile" proofs to fail.
  3602   - The theorems split_<typename>_case and split_<typename>_case_asm
  3603     have been renamed to <typename>.split and <typename>.split_asm.
  3604   - Since default sorts of type variables are now handled correctly,
  3605     some datatype definitions may have to be annotated with explicit
  3606     sort constraints.
  3607   - Primrec definitions no longer require function name and type
  3608     of recursive argument.
  3609 
  3610 Consider using isatool fixdatatype to adapt your theories and proof
  3611 scripts to the new package (backup your sources first!).
  3612 
  3613 
  3614 * HOL/record package: considerably improved implementation; now
  3615 includes concrete syntax for record types, terms, updates; theorems
  3616 for surjective pairing and splitting !!-bound record variables; proof
  3617 support is as follows:
  3618 
  3619   1) standard conversions (selectors or updates applied to record
  3620 constructor terms) are part of the standard simpset;
  3621 
  3622   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  3623 made part of standard simpset and claset via addIffs;
  3624 
  3625   3) a tactic for record field splitting (record_split_tac) is part of
  3626 the standard claset (addSWrapper);
  3627 
  3628 To get a better idea about these rules you may retrieve them via
  3629 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  3630 the name of your record type.
  3631 
  3632 The split tactic 3) conceptually simplifies by the following rule:
  3633 
  3634   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  3635 
  3636 Thus any record variable that is bound by meta-all will automatically
  3637 blow up into some record constructor term, consequently the
  3638 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  3639 solve record problems automatically.
  3640 
  3641 
  3642 * reorganized the main HOL image: HOL/Integ and String loaded by
  3643 default; theory Main includes everything;
  3644 
  3645 * automatic simplification of integer sums and comparisons, using cancellation;
  3646 
  3647 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  3648 
  3649 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  3650 
  3651 * many new identities for unions, intersections, set difference, etc.;
  3652 
  3653 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  3654 called split_if, split_split, split_sum_case and split_nat_case (to go
  3655 with add/delsplits);
  3656 
  3657 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  3658 (?x::unit) = (); this is made part of the default simpset, which COULD
  3659 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  3660 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  3661 unit_abs_eta_conv is added in order to counter the effect of
  3662 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  3663 %u.f();
  3664 
  3665 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  3666 makes more sense);
  3667 
  3668 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  3669   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  3670   disjointness reasoning but breaking a few old proofs.
  3671 
  3672 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  3673 to 'converse' from 'inverse' (for compatibility with ZF and some
  3674 literature);
  3675 
  3676 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  3677 the well-founded relation;
  3678 
  3679 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  3680     Compl A.  The "Compl" syntax remains available as input syntax for this
  3681     release ONLY.
  3682 
  3683 * HOL/Update: new theory of function updates:
  3684     f(a:=b) == %x. if x=a then b else f x
  3685 may also be iterated as in f(a:=b,c:=d,...);
  3686 
  3687 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  3688 
  3689 * HOL/List:
  3690   - new function list_update written xs[i:=v] that updates the i-th
  3691     list position. May also be iterated as in xs[i:=a,j:=b,...].
  3692   - new function `upt' written [i..j(] which generates the list
  3693     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  3694     bound write [i..j], which is a shorthand for [i..j+1(].
  3695   - new lexicographic orderings and corresponding wellfoundedness theorems.
  3696 
  3697 * HOL/Arith:
  3698   - removed 'pred' (predecessor) function;
  3699   - generalized some theorems about n-1;
  3700   - many new laws about "div" and "mod";
  3701   - new laws about greatest common divisors (see theory ex/Primes);
  3702 
  3703 * HOL/Relation: renamed the relational operator r^-1 "converse"
  3704 instead of "inverse";
  3705 
  3706 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  3707   of the multiset ordering;
  3708 
  3709 * directory HOL/Real: a construction of the reals using Dedekind cuts
  3710   (not included by default);
  3711 
  3712 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  3713 
  3714 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  3715   programs, i.e. different program variables may have different types.
  3716 
  3717 * calling (stac rew i) now fails if "rew" has no effect on the goal
  3718   [previously, this check worked only if the rewrite rule was unconditional]
  3719   Now rew can involve either definitions or equalities (either == or =).
  3720 
  3721 
  3722 *** ZF ***
  3723 
  3724 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  3725   only the theorems proved on ZF.ML;
  3726 
  3727 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  3728   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  3729   disjointness reasoning but breaking a few old proofs.
  3730 
  3731 * ZF/Update: new theory of function updates
  3732     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  3733   may also be iterated as in f(a:=b,c:=d,...);
  3734 
  3735 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  3736 
  3737 * calling (stac rew i) now fails if "rew" has no effect on the goal
  3738   [previously, this check worked only if the rewrite rule was unconditional]
  3739   Now rew can involve either definitions or equalities (either == or =).
  3740 
  3741 * case_tac provided for compatibility with HOL
  3742     (like the old excluded_middle_tac, but with subgoals swapped)
  3743 
  3744 
  3745 *** Internal programming interfaces ***
  3746 
  3747 * Pure: several new basic modules made available for general use, see
  3748 also src/Pure/README;
  3749 
  3750 * improved the theory data mechanism to support encapsulation (data
  3751 kind name replaced by private Object.kind, acting as authorization
  3752 key); new type-safe user interface via functor TheoryDataFun; generic
  3753 print_data function becomes basically useless;
  3754 
  3755 * removed global_names compatibility flag -- all theory declarations
  3756 are qualified by default;
  3757 
  3758 * module Pure/Syntax now offers quote / antiquote translation
  3759 functions (useful for Hoare logic etc. with implicit dependencies);
  3760 see HOL/ex/Antiquote for an example use;
  3761 
  3762 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  3763 cterm -> thm;
  3764 
  3765 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  3766 subgoal;
  3767 
  3768 * Display.print_goals function moved to Locale.print_goals;
  3769 
  3770 * standard print function for goals supports current_goals_markers
  3771 variable for marking begin of proof, end of proof, start of goal; the
  3772 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  3773 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  3774 for example;
  3775 
  3776 
  3777 
  3778 New in Isabelle98 (January 1998)
  3779 --------------------------------
  3780 
  3781 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  3782 
  3783 * changed lexical syntax of terms / types: dots made part of long
  3784 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  3785 
  3786 * simpset (and claset) reference variable replaced by functions
  3787 simpset / simpset_ref;
  3788 
  3789 * no longer supports theory aliases (via merge) and non-trivial
  3790 implicit merge of thms' signatures;
  3791 
  3792 * most internal names of constants changed due to qualified names;
  3793 
  3794 * changed Pure/Sequence interface (see Pure/seq.ML);
  3795 
  3796 
  3797 *** General Changes ***
  3798 
  3799 * hierachically structured name spaces (for consts, types, axms, thms
  3800 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  3801 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  3802 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  3803 long_names for fully qualified output names; NOTE: ML programs
  3804 (special tactics, packages etc.) referring to internal names may have
  3805 to be adapted to cope with fully qualified names; in case of severe
  3806 backward campatibility problems try setting 'global_names' at compile
  3807 time to have enrything declared within a flat name space; one may also
  3808 fine tune name declarations in theories via the 'global' and 'local'
  3809 section;
  3810 
  3811 * reimplemented the implicit simpset and claset using the new anytype
  3812 data filed in signatures; references simpset:simpset ref etc. are
  3813 replaced by functions simpset:unit->simpset and
  3814 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  3815 to patch your ML files accordingly;
  3816 
  3817 * HTML output now includes theory graph data for display with Java
  3818 applet or isatool browser; data generated automatically via isatool
  3819 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  3820 
  3821 * defs may now be conditional; improved rewrite_goals_tac to handle
  3822 conditional equations;
  3823 
  3824 * defs now admits additional type arguments, using TYPE('a) syntax;
  3825 
  3826 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  3827 creates a new theory node; implicit merge of thms' signatures is
  3828 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  3829 transfer:theory->thm->thm in (rare) cases;
  3830 
  3831 * improved handling of draft signatures / theories; draft thms (and
  3832 ctyps, cterms) are automatically promoted to real ones;
  3833 
  3834 * slightly changed interfaces for oracles: admit many per theory, named
  3835 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  3836 
  3837 * print_goals: optional output of const types (set show_consts and
  3838 show_types);
  3839 
  3840 * improved output of warnings (###) and errors (***);
  3841 
  3842 * subgoal_tac displays a warning if the new subgoal has type variables;
  3843 
  3844 * removed old README and Makefiles;
  3845 
  3846 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  3847 
  3848 * removed obsolete init_pps and init_database;
  3849 
  3850 * deleted the obsolete tactical STATE, which was declared by
  3851     fun STATE tacfun st = tacfun st st;
  3852 
  3853 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  3854 (which abbreviates $HOME);
  3855 
  3856 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  3857 use isatool fixseq to adapt your ML programs (this works for fully
  3858 qualified references to the Sequence structure only!);
  3859 
  3860 * use_thy no longer requires writable current directory; it always
  3861 reloads .ML *and* .thy file, if either one is out of date;
  3862 
  3863 
  3864 *** Classical Reasoner ***
  3865 
  3866 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  3867 tactics that use classical reasoning to simplify a subgoal without
  3868 splitting it into several subgoals;
  3869 
  3870 * Safe_tac: like safe_tac but uses the default claset;
  3871 
  3872 
  3873 *** Simplifier ***
  3874 
  3875 * added simplification meta rules:
  3876     (asm_)(full_)simplify: simpset -> thm -> thm;
  3877 
  3878 * simplifier.ML no longer part of Pure -- has to be loaded by object
  3879 logics (again);
  3880 
  3881 * added prems argument to simplification procedures;
  3882 
  3883 * HOL, FOL, ZF: added infix function `addsplits':
  3884   instead of `<simpset> setloop (split_tac <thms>)'
  3885   you can simply write `<simpset> addsplits <thms>'
  3886 
  3887 
  3888 *** Syntax ***
  3889 
  3890 * TYPE('a) syntax for type reflection terms;
  3891 
  3892 * no longer handles consts with name "" -- declare as 'syntax' instead;
  3893 
  3894 * pretty printer: changed order of mixfix annotation preference (again!);
  3895 
  3896 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  3897 
  3898 
  3899 *** HOL ***
  3900 
  3901 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  3902   with `addloop' of the simplifier to faciliate case splitting in premises.
  3903 
  3904 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  3905 
  3906 * HOL/Auth: new protocol proofs including some for the Internet
  3907   protocol TLS;
  3908 
  3909 * HOL/Map: new theory of `maps' a la VDM;
  3910 
  3911 * HOL/simplifier: simplification procedures nat_cancel_sums for
  3912 cancelling out common nat summands from =, <, <= (in)equalities, or
  3913 differences; simplification procedures nat_cancel_factor for
  3914 cancelling common factor from =, <, <= (in)equalities over natural
  3915 sums; nat_cancel contains both kinds of procedures, it is installed by
  3916 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  3917 
  3918 * HOL/simplifier: terms of the form
  3919   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  3920   are rewritten to
  3921   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  3922   and those of the form
  3923   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  3924   are rewritten to
  3925   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  3926 
  3927 * HOL/datatype
  3928   Each datatype `t' now comes with a theorem `split_t_case' of the form
  3929 
  3930   P(t_case f1 ... fn x) =
  3931      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  3932         ...
  3933        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  3934      )
  3935 
  3936   and a theorem `split_t_case_asm' of the form
  3937 
  3938   P(t_case f1 ... fn x) =
  3939     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  3940         ...
  3941        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  3942      )
  3943   which can be added to a simpset via `addsplits'. The existing theorems
  3944   expand_list_case and expand_option_case have been renamed to
  3945   split_list_case and split_option_case.
  3946 
  3947 * HOL/Arithmetic:
  3948   - `pred n' is automatically converted to `n-1'.
  3949     Users are strongly encouraged not to use `pred' any longer,
  3950     because it will disappear altogether at some point.
  3951   - Users are strongly encouraged to write "0 < n" rather than
  3952     "n ~= 0". Theorems and proof tools have been modified towards this
  3953     `standard'.
  3954 
  3955 * HOL/Lists:
  3956   the function "set_of_list" has been renamed "set" (and its theorems too);
  3957   the function "nth" now takes its arguments in the reverse order and
  3958   has acquired the infix notation "!" as in "xs!n".
  3959 
  3960 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  3961 
  3962 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  3963   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  3964 
  3965 * HOL/record: extensible records with schematic structural subtyping
  3966 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  3967 still lacks various theorems and concrete record syntax;
  3968 
  3969 
  3970 *** HOLCF ***
  3971 
  3972 * removed "axioms" and "generated by" sections;
  3973 
  3974 * replaced "ops" section by extended "consts" section, which is capable of
  3975   handling the continuous function space "->" directly;
  3976 
  3977 * domain package:
  3978   . proves theorems immediately and stores them in the theory,
  3979   . creates hierachical name space,
  3980   . now uses normal mixfix annotations (instead of cinfix...),
  3981   . minor changes to some names and values (for consistency),
  3982   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  3983   . separator between mutual domain defs: changed "," to "and",
  3984   . improved handling of sort constraints;  now they have to
  3985     appear on the left-hand side of the equations only;
  3986 
  3987 * fixed LAM <x,y,zs>.b syntax;
  3988 
  3989 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  3990 adm (%x. P (t x)), where P is chainfinite and t continuous;
  3991 
  3992 
  3993 *** FOL and ZF ***
  3994 
  3995 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  3996   with `addloop' of the simplifier to faciliate case splitting in premises.
  3997 
  3998 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  3999 in HOL, they strip ALL and --> from proved theorems;
  4000 
  4001 
  4002 
  4003 New in Isabelle94-8 (May 1997)
  4004 ------------------------------
  4005 
  4006 *** General Changes ***
  4007 
  4008 * new utilities to build / run / maintain Isabelle etc. (in parts
  4009 still somewhat experimental); old Makefiles etc. still functional;
  4010 
  4011 * new 'Isabelle System Manual';
  4012 
  4013 * INSTALL text, together with ./configure and ./build scripts;
  4014 
  4015 * reimplemented type inference for greater efficiency, better error
  4016 messages and clean internal interface;
  4017 
  4018 * prlim command for dealing with lots of subgoals (an easier way of
  4019 setting goals_limit);
  4020 
  4021 
  4022 *** Syntax ***
  4023 
  4024 * supports alternative (named) syntax tables (parser and pretty
  4025 printer); internal interface is provided by add_modesyntax(_i);
  4026 
  4027 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  4028 be used in conjunction with the Isabelle symbol font; uses the
  4029 "symbols" syntax table;
  4030 
  4031 * added token_translation interface (may translate name tokens in
  4032 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  4033 the current print_mode); IMPORTANT: user print translation functions
  4034 are responsible for marking newly introduced bounds
  4035 (Syntax.mark_boundT);
  4036 
  4037 * token translations for modes "xterm" and "xterm_color" that display
  4038 names in bold, underline etc. or colors (which requires a color
  4039 version of xterm);
  4040 
  4041 * infixes may now be declared with names independent of their syntax;
  4042 
  4043 * added typed_print_translation (like print_translation, but may
  4044 access type of constant);
  4045 
  4046 
  4047 *** Classical Reasoner ***
  4048 
  4049 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  4050 some limitations.  Blast_tac...
  4051   + ignores addss, addbefore, addafter; this restriction is intrinsic
  4052   + ignores elimination rules that don't have the correct format
  4053         (the conclusion MUST be a formula variable)
  4054   + ignores types, which can make HOL proofs fail
  4055   + rules must not require higher-order unification, e.g. apply_type in ZF
  4056     [message "Function Var's argument not a bound variable" relates to this]
  4057   + its proof strategy is more general but can actually be slower
  4058 
  4059 * substitution with equality assumptions no longer permutes other
  4060 assumptions;
  4061 
  4062 * minor changes in semantics of addafter (now called addaltern); renamed
  4063 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  4064 (and access functions for it);
  4065 
  4066 * improved combination of classical reasoner and simplifier:
  4067   + functions for handling clasimpsets
  4068   + improvement of addss: now the simplifier is called _after_ the
  4069     safe steps.
  4070   + safe variant of addss called addSss: uses safe simplifications
  4071     _during_ the safe steps. It is more complete as it allows multiple
  4072     instantiations of unknowns (e.g. with slow_tac).
  4073 
  4074 *** Simplifier ***
  4075 
  4076 * added interface for simplification procedures (functions that
  4077 produce *proven* rewrite rules on the fly, depending on current
  4078 redex);
  4079 
  4080 * ordering on terms as parameter (used for ordered rewriting);
  4081 
  4082 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  4083 
  4084 * the solver is now split into a safe and an unsafe part.
  4085 This should be invisible for the normal user, except that the
  4086 functions setsolver and addsolver have been renamed to setSolver and
  4087 addSolver; added safe_asm_full_simp_tac;
  4088 
  4089 
  4090 *** HOL ***
  4091 
  4092 * a generic induction tactic `induct_tac' which works for all datatypes and
  4093 also for type `nat';
  4094 
  4095 * a generic case distinction tactic `exhaust_tac' which works for all
  4096 datatypes and also for type `nat';
  4097 
  4098 * each datatype comes with a function `size';
  4099 
  4100 * patterns in case expressions allow tuple patterns as arguments to
  4101 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  4102 
  4103 * primrec now also works with type nat;
  4104 
  4105 * recdef: a new declaration form, allows general recursive functions to be
  4106 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  4107 
  4108 * the constant for negation has been renamed from "not" to "Not" to
  4109 harmonize with FOL, ZF, LK, etc.;
  4110 
  4111 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  4112 infinite lists;
  4113 
  4114 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  4115 
  4116 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  4117 problems in commutative rings, using axiomatic type classes for + and *;
  4118 
  4119 * more examples in HOL/MiniML and HOL/Auth;
  4120 
  4121 * more default rewrite rules for quantifiers, union/intersection;
  4122 
  4123 * a new constant `arbitrary == @x.False';
  4124 
  4125 * HOLCF/IOA replaces old HOL/IOA;
  4126 
  4127 * HOLCF changes: derived all rules and arities
  4128   + axiomatic type classes instead of classes
  4129   + typedef instead of faking type definitions
  4130   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  4131   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  4132   + eliminated the types void, one, tr
  4133   + use unit lift and bool lift (with translations) instead of one and tr
  4134   + eliminated blift from Lift3.thy (use Def instead of blift)
  4135   all eliminated rules are derived as theorems --> no visible changes ;
  4136 
  4137 
  4138 *** ZF ***
  4139 
  4140 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  4141 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  4142 as ZF_cs addSIs [equalityI];
  4143 
  4144 
  4145 
  4146 New in Isabelle94-7 (November 96)
  4147 ---------------------------------
  4148 
  4149 * allowing negative levels (as offsets) in prlev and choplev;
  4150 
  4151 * super-linear speedup for large simplifications;
  4152 
  4153 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  4154 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  4155 FAIL); can suppress it using the command Delsimps (ex_simps @
  4156 all_simps); De Morgan laws are also now included, by default;
  4157 
  4158 * improved printing of ==>  :  ~:
  4159 
  4160 * new object-logic "Sequents" adds linear logic, while replacing LK
  4161 and Modal (thanks to Sara Kalvala);
  4162 
  4163 * HOL/Auth: correctness proofs for authentication protocols;
  4164 
  4165 * HOL: new auto_tac combines rewriting and classical reasoning (many
  4166 examples on HOL/Auth);
  4167 
  4168 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  4169 the rewriter and classical reasoner simultaneously;
  4170 
  4171 * function uresult no longer returns theorems in "standard" format;
  4172 regain previous version by: val uresult = standard o uresult;
  4173 
  4174 
  4175 
  4176 New in Isabelle94-6
  4177 -------------------
  4178 
  4179 * oracles -- these establish an interface between Isabelle and trusted
  4180 external reasoners, which may deliver results as theorems;
  4181 
  4182 * proof objects (in particular record all uses of oracles);
  4183 
  4184 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  4185 
  4186 * "constdefs" section in theory files;
  4187 
  4188 * "primrec" section (HOL) no longer requires names;
  4189 
  4190 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  4191 
  4192 
  4193 
  4194 New in Isabelle94-5
  4195 -------------------
  4196 
  4197 * reduced space requirements;
  4198 
  4199 * automatic HTML generation from theories;
  4200 
  4201 * theory files no longer require "..." (quotes) around most types;
  4202 
  4203 * new examples, including two proofs of the Church-Rosser theorem;
  4204 
  4205 * non-curried (1994) version of HOL is no longer distributed;
  4206 
  4207 
  4208 
  4209 New in Isabelle94-4
  4210 -------------------
  4211 
  4212 * greatly reduced space requirements;
  4213 
  4214 * theory files (.thy) no longer require \...\ escapes at line breaks;
  4215 
  4216 * searchable theorem database (see the section "Retrieving theorems" on
  4217 page 8 of the Reference Manual);
  4218 
  4219 * new examples, including Grabczewski's monumental case study of the
  4220 Axiom of Choice;
  4221 
  4222 * The previous version of HOL renamed to Old_HOL;
  4223 
  4224 * The new version of HOL (previously called CHOL) uses a curried syntax
  4225 for functions.  Application looks like f a b instead of f(a,b);
  4226 
  4227 * Mutually recursive inductive definitions finally work in HOL;
  4228 
  4229 * In ZF, pattern-matching on tuples is now available in all abstractions and
  4230 translates to the operator "split";
  4231 
  4232 
  4233 
  4234 New in Isabelle94-3
  4235 -------------------
  4236 
  4237 * new infix operator, addss, allowing the classical reasoner to
  4238 perform simplification at each step of its search.  Example:
  4239         fast_tac (cs addss ss)
  4240 
  4241 * a new logic, CHOL, the same as HOL, but with a curried syntax
  4242 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  4243 look like (a,b) instead of <a,b>;
  4244 
  4245 * PLEASE NOTE: CHOL will eventually replace HOL!
  4246 
  4247 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  4248 It translates to the operator "split".  A new theory of integers is available;
  4249 
  4250 * In ZF, integer numerals now denote two's-complement binary integers.
  4251 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  4252 
  4253 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  4254 of the Axiom of Choice;
  4255 
  4256 
  4257 
  4258 New in Isabelle94-2
  4259 -------------------
  4260 
  4261 * Significantly faster resolution;
  4262 
  4263 * the different sections in a .thy file can now be mixed and repeated
  4264 freely;
  4265 
  4266 * Database of theorems for FOL, HOL and ZF.  New
  4267 commands including qed, qed_goal and bind_thm store theorems in the database.
  4268 
  4269 * Simple database queries: return a named theorem (get_thm) or all theorems of
  4270 a given theory (thms_of), or find out what theory a theorem was proved in
  4271 (theory_of_thm);
  4272 
  4273 * Bugs fixed in the inductive definition and datatype packages;
  4274 
  4275 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  4276 and HOL_dup_cs obsolete;
  4277 
  4278 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  4279 have been removed;
  4280 
  4281 * Simpler definition of function space in ZF;
  4282 
  4283 * new results about cardinal and ordinal arithmetic in ZF;
  4284 
  4285 * 'subtype' facility in HOL for introducing new types as subsets of existing
  4286 types;
  4287 
  4288 
  4289 $Id$