NEWS
author nipkow
Wed Dec 01 18:17:01 2004 +0100 (2004-12-01)
changeset 15356 cfd08f5e0bdd
parent 15350 53d2927d9680
child 15361 bb2dd95c8c5e
permissions -rw-r--r--
*** empty log message ***
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** General ***
     8 
     9 * Document preparation: new antiquotations @{lhs thm} and @{rhs thm}
    10   printing the lhs/rhs of definitions, equations, inequations etc. 
    11 
    12 * isatool usedir: new option -f that allows specification of the ML
    13   file to be used by Isabelle; default is ROOT.ML.
    14 
    15 * Theory headers: the new header syntax for Isar theories is
    16 
    17   theory <name>
    18   imports <theory1> ... <theoryn>
    19   begin
    20 
    21   optionally also with a "files" section. The syntax
    22 
    23   theory <name> = <theory1> + ... + <theoryn>:
    24 
    25   will still be supported for some time but will eventually disappear.
    26   The syntax of old-style theories has not changed.
    27 
    28 * Provers/quasi.ML:  new transitivity reasoners for transitivity only
    29   and quasi orders.
    30 
    31 * Provers/trancl.ML:  new transitivity reasoner for transitive and
    32   reflexive-transitive closure of relations.
    33 
    34 * Provers/blast.ML:  new reference depth_limit to make blast's depth
    35   limit (previously hard-coded with a value of 20) user-definable.
    36 
    37 * Pure: considerably improved version of 'constdefs' command.  Now
    38   performs automatic type-inference of declared constants; additional
    39   support for local structure declarations (cf. locales and HOL
    40   records), see also isar-ref manual.  Potential INCOMPATIBILITY: need
    41   to observe strictly sequential dependencies of definitions within a
    42   single 'constdefs' section; moreover, the declared name needs to be
    43   an identifier.  If all fails, consider to fall back on 'consts' and
    44   'defs' separately.
    45 
    46 * Pure: improved indexed syntax and implicit structures.  First of
    47   all, indexed syntax provides a notational device for subscripted
    48   application, using the new syntax \<^bsub>term\<^esub> for arbitrary
    49   expressions.  Secondly, in a local context with structure
    50   declarations, number indexes \<^sub>n or the empty index (default
    51   number 1) refer to a certain fixed variable implicitly; option
    52   show_structs controls printing of implicit structures.  Typical
    53   applications of these concepts involve record types and locales.
    54 
    55 * Pure: clear separation of logical types and nonterminals, where the
    56   latter may only occur in 'syntax' specifications or type
    57   abbreviations.  Before that distinction was only partially
    58   implemented via type class "logic" vs. "{}".  Potential
    59   INCOMPATIBILITY in rare cases of improper use of 'types'/'consts'
    60   instead of 'nonterminals'/'syntax'.  Some very exotic syntax
    61   specifications may require further adaption (e.g. Cube/Base.thy).
    62 
    63 * Pure: removed obsolete type class "logic", use the top sort {}
    64   instead.  Note that non-logical types should be declared as
    65   'nonterminals' rather than 'types'.  INCOMPATIBILITY for new
    66   object-logic specifications.
    67 
    68 * Pure: print_tac now outputs the goal through the trace channel.
    69 
    70 * Pure: reference Namespace.unique_names included.  If true the
    71   (shortest) namespace-prefix is printed to disambiguate conflicts (as
    72   yet). If false the first entry wins (as during parsing). Default
    73   value is true.
    74 
    75 * Pure: tuned internal renaming of symbolic identifiers -- attach
    76   primes instead of base 26 numbers.
    77 
    78 * Pure/Syntax: inner syntax includes (*(*nested*) comments*).
    79 
    80 * Pure/Syntax: pretty pinter now supports unbreakable blocks,
    81   specified in mixfix annotations as "(00...)".
    82 
    83 * Pure/Syntax: 'advanced' translation functions (parse_translation
    84   etc.) may depend on the signature of the theory context being
    85   presently used for parsing/printing, see also isar-ref manual.
    86 
    87 * Pure/Simplifier: simplification procedures may now take the current
    88   simpset into account (cf. Simplifier.simproc(_i) / mk_simproc
    89   interface), which is very useful for calling the Simplifier
    90   recursively.  Minor INCOMPATIBILITY: the 'prems' argument of
    91   simprocs is gone -- use prems_of_ss on the simpset instead.
    92   Moreover, the low-level mk_simproc no longer applies Logic.varify
    93   internally, to allow for use in a context of fixed variables.
    94 
    95 * Provers: Simplifier and Classical Reasoner now support proof context
    96   dependent plug-ins (simprocs, solvers, wrappers etc.).  These extra
    97   components are stored in the theory and patched into the
    98   simpset/claset when used in an Isar proof context.  Context
    99   dependent components are maintained by the following theory
   100   operations:
   101 
   102     Simplifier.add_context_simprocs
   103     Simplifier.del_context_simprocs
   104     Simplifier.set_context_subgoaler
   105     Simplifier.reset_context_subgoaler
   106     Simplifier.add_context_looper
   107     Simplifier.del_context_looper
   108     Simplifier.add_context_unsafe_solver
   109     Simplifier.add_context_safe_solver
   110 
   111     Classical.add_context_safe_wrapper
   112     Classical.del_context_safe_wrapper
   113     Classical.add_context_unsafe_wrapper
   114     Classical.del_context_unsafe_wrapper
   115 
   116   IMPORTANT NOTE: proof tools (methods etc.) need to use
   117   local_simpset_of and local_claset_of to instead of the primitive
   118   Simplifier.get_local_simpset and Classical.get_local_claset,
   119   respectively, in order to see the context dependent fields!
   120 
   121 * Document preparation: antiquotations now provide the option
   122   'locale=NAME' to specify an alternative context used for evaluating
   123   and printing the subsequent argument, as in @{thm [locale=LC]
   124   fold_commute}, for example.
   125 
   126 * Document preparation: commands 'display_drafts' and 'print_drafts'
   127   perform simple output of raw sources.  Only those symbols that do
   128   not require additional LaTeX packages (depending on comments in
   129   isabellesym.sty) are displayed properly, everything else is left
   130   verbatim.  We use isatool display and isatool print as front ends;
   131   these are subject to the DVI_VIEWER and PRINT_COMMAND settings,
   132   respectively.
   133 
   134 * ML: output via the Isabelle channels of writeln/warning/error
   135   etc. is now passed through Output.output, with a hook for arbitrary
   136   transformations depending on the print_mode (cf. Output.add_mode --
   137   the first active mode that provides a output function wins).
   138   Already formatted output may be embedded into further text via
   139   Output.raw; the result of Pretty.string_of/str_of and derived
   140   functions (string_of_term/cterm/thm etc.) is already marked raw to
   141   accommodate easy composition of diagnostic messages etc.
   142   Programmers rarely need to care about Output.output or Output.raw at
   143   all, with some notable exceptions: Output.output is required when
   144   bypassing the standard channels (writeln etc.), or in token
   145   translations to produce properly formatted results; Output.raw is
   146   required when capturing already output material that will eventually
   147   be presented to the user a second time.  For the default print mode,
   148   both Output.output and Output.raw have no effect.
   149 
   150 
   151 *** Isar ***
   152 
   153 * Locales:
   154   - "includes" disallowed in declaration of named locales (command "locale").
   155   - Fixed parameter management in theorem generation for goals with "includes".
   156     INCOMPATIBILITY: rarely, the generated theorem statement is different.
   157  
   158 *** HOL ***
   159 
   160 * Datatype induction via method `induct' now preserves the name of the
   161   induction variable. For example, when proving P(xs::'a list) by induction
   162   on xs, the induction step is now P(xs) ==> P(a#xs) rather than
   163   P(list) ==> P(a#list) as previously.
   164 
   165 * HOL/record: reimplementation of records. Improved scalability for
   166   records with many fields, avoiding performance problems for type
   167   inference. Records are no longer composed of nested field types, but
   168   of nested extension types. Therefore the record type only grows
   169   linear in the number of extensions and not in the number of fields.
   170   The top-level (users) view on records is preserved.  Potential
   171   INCOMPATIBILITY only in strange cases, where the theory depends on
   172   the old record representation. The type generated for a record is
   173   called <record_name>_ext_type.
   174 
   175 * HOL/record: Reference record_quick_and_dirty_sensitive can be
   176   enabled to skip the proofs triggered by a record definition or a
   177   simproc (if quick_and_dirty is enabled). Definitions of large
   178   records can take quite long.
   179 
   180 * HOL/record: "record_upd_simproc" for simplification of multiple
   181   record updates enabled by default.  Moreover, trivial updates are
   182   also removed: r(|x := x r|) = r.  INCOMPATIBILITY: old proofs break
   183   occasionally, since simplification is more powerful by default.
   184 
   185 * HOL: symbolic syntax of Hilbert Choice Operator is now as follows:
   186 
   187   syntax (epsilon)
   188     "_Eps" :: "[pttrn, bool] => 'a"    ("(3\<some>_./ _)" [0, 10] 10)
   189 
   190   The symbol \<some> is displayed as the alternative epsilon of LaTeX
   191   and x-symbol; use option '-m epsilon' to get it actually printed.
   192   Moreover, the mathematically important symbolic identifier
   193   \<epsilon> becomes available as variable, constant etc.
   194 
   195 * HOL: "x > y" abbreviates "y < x" and "x >= y" abbreviates "y <= x"
   196 
   197 * HOL/SetInterval: The syntax for open intervals has changed:
   198 
   199   Old         New
   200   {..n(}   -> {..<n}
   201   {)n..}   -> {n<..}
   202   {m..n(}  -> {m..<n}
   203   {)m..n}  -> {m<..n}
   204   {)m..n(} -> {m<..<n}
   205 
   206   The old syntax is still supported but will disappear in the future.
   207   For conversion use the following emacs search and replace patterns:
   208 
   209   {)\([^\.]*\)\.\.  ->  {\1<\.\.}
   210   \.\.\([^(}]*\)(}  ->  \.\.<\1}
   211 
   212   They are not perfect but work quite well.
   213 
   214 * HOL: The syntax for 'setsum', summation over finite sets, has changed:
   215 
   216   The syntax for 'setsum (%x. e) A' used to be '\<Sum>x:A. e'
   217   and is now either 'SUM x:A. e' or '\<Sum>x\<in>A. e'.
   218 
   219   There is new syntax for summation over finite sets:
   220 
   221   '\<Sum>x | P. e'    is the same as  'setsum (%x. e) {x. P}'
   222   '\<Sum>x=a..b. e'   is the same as  'setsum (%x. e) {a..b}'
   223   '\<Sum>x=a..<b. e'  is the same as  'setsum (%x. e) {a..<b}'
   224   '\<Sum>x<k. e'      is the same as  'setsum (%x. e) {..<k}'
   225 
   226   Function 'Summation' over nat is gone, its syntax '\<Sum>i<k. e'
   227   now translates into 'setsum' as above.
   228 
   229 * HOL: Finite set induction: In Isar proofs, the insert case is now
   230   "case (insert x F)" instead of the old counterintuitive "case (insert F x)".
   231 
   232 * HOL/Simplifier:
   233 
   234   - Is now set up to reason about transitivity chains involving "trancl"
   235   (r^+) and "rtrancl" (r^*) by setting up tactics provided by
   236   Provers/trancl.ML as additional solvers.  INCOMPATIBILITY: old proofs break
   237   occasionally as simplification may now solve more goals than previously.
   238 
   239   - Converts x <= y into x = y if assumption y <= x is present.  Works for
   240   all partial orders (class "order"), in particular numbers and sets. For
   241   linear orders (e.g. numbers) it treats ~ x < y just like y <= x.
   242 
   243 * HOL: new 'isatool dimacs2hol' to convert files in DIMACS CNF format
   244   (containing Boolean satisfiability problems) into Isabelle/HOL theories.
   245 
   246 
   247 *** HOLCF ***
   248 
   249 * HOLCF: discontinued special version of 'constdefs' (which used to
   250   support continuous functions) in favor of the general Pure one with
   251   full type-inference.
   252 
   253 
   254 *** ZF ***
   255 
   256 * ZF/ex/{Group,Ring}: examples in abstract algebra, including the
   257   First Isomorphism Theorem (on quotienting by the kernel of a
   258   homomorphism).
   259 
   260 * ZF/Simplifier: install second copy of type solver that actually
   261   makes use of TC rules declared to Isar proof contexts (or locales);
   262   the old version is still required for ML proof scripts.
   263 
   264 
   265 
   266 New in Isabelle2004 (April 2004)
   267 --------------------------------
   268 
   269 *** General ***
   270 
   271 * Provers/order.ML:  new efficient reasoner for partial and linear orders.
   272   Replaces linorder.ML.
   273 
   274 * Pure: Greek letters (except small lambda, \<lambda>), as well as Gothic
   275   (\<aa>...\<zz>\<AA>...\<ZZ>), calligraphic (\<A>...\<Z>), and Euler
   276   (\<a>...\<z>), are now considered normal letters, and can therefore
   277   be used anywhere where an ASCII letter (a...zA...Z) has until
   278   now. COMPATIBILITY: This obviously changes the parsing of some
   279   terms, especially where a symbol has been used as a binder, say
   280   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed
   281   as an identifier.  Fix it by inserting a space around former
   282   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in
   283   existing theory and ML files.
   284 
   285 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.
   286 
   287 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now
   288   allowed in identifiers. Similar to Greek letters \<^isub> is now considered
   289   a normal (but invisible) letter. For multiple letter subscripts repeat
   290   \<^isub> like this: x\<^isub>1\<^isub>2.
   291 
   292 * Pure: There are now sub-/superscripts that can span more than one
   293   character. Text between \<^bsub> and \<^esub> is set in subscript in
   294   ProofGeneral and LaTeX, text between \<^bsup> and \<^esup> in
   295   superscript. The new control characters are not identifier parts.
   296 
   297 * Pure: Control-symbols of the form \<^raw:...> will literally print the
   298   content of "..." to the latex file instead of \isacntrl... . The "..."
   299   may consist of any printable characters excluding the end bracket >.
   300 
   301 * Pure: Using new Isar command "finalconsts" (or the ML functions
   302   Theory.add_finals or Theory.add_finals_i) it is now possible to
   303   declare constants "final", which prevents their being given a definition
   304   later.  It is useful for constants whose behaviour is fixed axiomatically
   305   rather than definitionally, such as the meta-logic connectives.
   306 
   307 * Pure: 'instance' now handles general arities with general sorts
   308   (i.e. intersections of classes),
   309 
   310 * Presentation: generated HTML now uses a CSS style sheet to make layout
   311   (somewhat) independent of content. It is copied from lib/html/isabelle.css.
   312   It can be changed to alter the colors/layout of generated pages.
   313 
   314 
   315 *** Isar ***
   316 
   317 * Tactic emulation methods rule_tac, erule_tac, drule_tac, frule_tac,
   318   cut_tac, subgoal_tac and thin_tac:
   319   - Now understand static (Isar) contexts.  As a consequence, users of Isar
   320     locales are no longer forced to write Isar proof scripts.
   321     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
   322     emulations.
   323   - INCOMPATIBILITY: names of variables to be instantiated may no
   324     longer be enclosed in quotes.  Instead, precede variable name with `?'.
   325     This is consistent with the instantiation attribute "where".
   326 
   327 * Attributes "where" and "of":
   328   - Now take type variables of instantiated theorem into account when reading
   329     the instantiation string.  This fixes a bug that caused instantiated
   330     theorems to have too special types in some circumstances.
   331   - "where" permits explicit instantiations of type variables.
   332 
   333 * Calculation commands "moreover" and "also" no longer interfere with
   334   current facts ("this"), admitting arbitrary combinations with "then"
   335   and derived forms.
   336 
   337 * Locales:
   338   - Goal statements involving the context element "includes" no longer
   339     generate theorems with internal delta predicates (those ending on
   340     "_axioms") in the premise.
   341     Resolve particular premise with <locale>.intro to obtain old form.
   342   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
   343     specification and "includes" elements in goal statement.
   344   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
   345     [intro?] and [elim?] (respectively) by default.
   346   - Experimental command for instantiation of locales in proof contexts:
   347         instantiate <label>[<attrs>]: <loc>
   348     Instantiates locale <loc> and adds all its theorems to the current context
   349     taking into account their attributes.  Label and attrs are optional
   350     modifiers, like in theorem declarations.  If present, names of
   351     instantiated theorems are qualified with <label>, and the attributes
   352     <attrs> are applied after any attributes these theorems might have already.
   353       If the locale has assumptions, a chained fact of the form
   354     "<loc> t1 ... tn" is expected from which instantiations of the parameters
   355     are derived.  The command does not support old-style locales declared
   356     with "locale (open)".
   357       A few (very simple) examples can be found in FOL/ex/LocaleInst.thy.
   358 
   359 * HOL: Tactic emulation methods induct_tac and case_tac understand static
   360   (Isar) contexts.
   361 
   362 
   363 *** HOL ***
   364 
   365 * Proof import: new image HOL4 contains the imported library from
   366   the HOL4 system with about 2500 theorems. It is imported by
   367   replaying proof terms produced by HOL4 in Isabelle. The HOL4 image
   368   can be used like any other Isabelle image.  See
   369   HOL/Import/HOL/README for more information.
   370 
   371 * Simplifier:
   372   - Much improved handling of linear and partial orders.
   373     Reasoners for linear and partial orders are set up for type classes
   374     "linorder" and "order" respectively, and are added to the default simpset
   375     as solvers.  This means that the simplifier can build transitivity chains
   376     to solve goals from the assumptions.
   377   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications
   378     of blast or auto after simplification become unnecessary because the goal
   379     is solved by simplification already.
   380 
   381 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws,
   382     all proved in axiomatic type classes for semirings, rings and fields.
   383 
   384 * Numerics:
   385   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are
   386     now formalized using the Ring_and_Field theory mentioned above.
   387   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently
   388     than before, because now they are set up once in a generic manner.
   389   - INCOMPATIBILITY: many type-specific arithmetic laws have gone.
   390     Look for the general versions in Ring_and_Field (and Power if they concern
   391     exponentiation).
   392 
   393 * Type "rat" of the rational numbers is now available in HOL-Complex.
   394 
   395 * Records:
   396   - Record types are now by default printed with their type abbreviation
   397     instead of the list of all field types. This can be configured via
   398     the reference "print_record_type_abbr".
   399   - Simproc "record_upd_simproc" for simplification of multiple updates added
   400     (not enabled by default).
   401   - Simproc "record_ex_sel_eq_simproc" to simplify EX x. sel r = x resp.
   402     EX x. x = sel r to True (not enabled by default).
   403   - Tactic "record_split_simp_tac" to split and simplify records added.
   404 
   405 * 'specification' command added, allowing for definition by
   406   specification.  There is also an 'ax_specification' command that
   407   introduces the new constants axiomatically.
   408 
   409 * arith(_tac) is now able to generate counterexamples for reals as well.
   410 
   411 * HOL-Algebra: new locale "ring" for non-commutative rings.
   412 
   413 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
   414   definitions, thanks to Sava Krsti\'{c} and John Matthews.
   415 
   416 * HOL-Matrix: a first theory for matrices in HOL with an application of
   417   matrix theory to linear programming.
   418 
   419 * Unions and Intersections:
   420   The latex output syntax of UN and INT has been changed
   421   from "\Union x \in A. B" to "\Union_{x \in A} B"
   422   i.e. the index formulae has become a subscript.
   423   Similarly for "\Union x. B", and for \Inter instead of \Union.
   424 
   425 * Unions and Intersections over Intervals:
   426   There is new short syntax "UN i<=n. A" for "UN i:{0..n}. A". There is
   427   also an x-symbol version with subscripts "\<Union>\<^bsub>i <= n\<^esub>. A"
   428   like in normal math, and corresponding versions for < and for intersection.
   429 
   430 * ML: the legacy theory structures Int and List have been removed. They had
   431   conflicted with ML Basis Library structures having the same names.
   432 
   433 * 'refute' command added to search for (finite) countermodels.  Only works
   434   for a fragment of HOL.  The installation of an external SAT solver is
   435   highly recommended.  See "HOL/Refute.thy" for details.
   436 
   437 * 'quickcheck' command: Allows to find counterexamples by evaluating
   438   formulae under an assignment of free variables to random values.
   439   In contrast to 'refute', it can deal with inductive datatypes,
   440   but cannot handle quantifiers. See "HOL/ex/Quickcheck_Examples.thy"
   441   for examples.
   442 
   443 
   444 *** HOLCF ***
   445 
   446 * Streams now come with concatenation and are part of the HOLCF image
   447 
   448 
   449 
   450 New in Isabelle2003 (May 2003)
   451 ------------------------------
   452 
   453 *** General ***
   454 
   455 * Provers/simplifier:
   456 
   457   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   458     Assumptions are now subject to complete mutual simplification,
   459     not just from left to right. The simplifier now preserves
   460     the order of assumptions.
   461 
   462     Potential INCOMPATIBILITY:
   463 
   464     -- simp sometimes diverges where the old version did
   465        not, e.g. invoking simp on the goal
   466 
   467         [| P (f x); y = x; f x = f y |] ==> Q
   468 
   469        now gives rise to the infinite reduction sequence
   470 
   471         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   472 
   473        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   474        kind of problem.
   475 
   476     -- Tactics combining classical reasoner and simplification (such as auto)
   477        are also affected by this change, because many of them rely on
   478        simp. They may sometimes diverge as well or yield a different numbers
   479        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   480        in case of problems. Sometimes subsequent calls to the classical
   481        reasoner will fail because a preceeding call to the simplifier too
   482        eagerly simplified the goal, e.g. deleted redundant premises.
   483 
   484   - The simplifier trace now shows the names of the applied rewrite rules
   485 
   486   - You can limit the number of recursive invocations of the simplifier
   487     during conditional rewriting (where the simplifie tries to solve the
   488     conditions before applying the rewrite rule):
   489     ML "simp_depth_limit := n"
   490     where n is an integer. Thus you can force termination where previously
   491     the simplifier would diverge.
   492 
   493   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   494 
   495   - No longer aborts on failed congruence proof.  Instead, the
   496     congruence is ignored.
   497 
   498 * Pure: New generic framework for extracting programs from constructive
   499   proofs. See HOL/Extraction.thy for an example instantiation, as well
   500   as HOL/Extraction for some case studies.
   501 
   502 * Pure: The main goal of the proof state is no longer shown by default, only
   503 the subgoals. This behaviour is controlled by a new flag.
   504    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   505 (ML: Proof.show_main_goal).
   506 
   507 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   508 rules whose conclusion matches subgoal 1:
   509       PG menu: Isabelle/Isar -> Show me -> matching rules
   510 The rules are ordered by how closely they match the subgoal.
   511 In particular, rules that solve a subgoal outright are displayed first
   512 (or rather last, the way they are printed).
   513 (ML: ProofGeneral.print_intros())
   514 
   515 * Pure: New flag trace_unify_fail causes unification to print
   516 diagnostic information (PG: in trace buffer) when it fails. This is
   517 useful for figuring out why single step proofs like rule, erule or
   518 assumption failed.
   519 
   520 * Pure: Locale specifications now produce predicate definitions
   521 according to the body of text (covering assumptions modulo local
   522 definitions); predicate "loc_axioms" covers newly introduced text,
   523 while "loc" is cumulative wrt. all included locale expressions; the
   524 latter view is presented only on export into the global theory
   525 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   526 on the old view without predicates;
   527 
   528 * Pure: predefined locales "var" and "struct" are useful for sharing
   529 parameters (as in CASL, for example); just specify something like
   530 ``var x + var y + struct M'' as import;
   531 
   532 * Pure: improved thms_containing: proper indexing of facts instead of
   533 raw theorems; check validity of results wrt. current name space;
   534 include local facts of proof configuration (also covers active
   535 locales), cover fixed variables in index; may use "_" in term
   536 specification; an optional limit for the number of printed facts may
   537 be given (the default is 40);
   538 
   539 * Pure: disallow duplicate fact bindings within new-style theory files
   540 (batch-mode only);
   541 
   542 * Provers: improved induct method: assumptions introduced by case
   543 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   544 the goal statement); "foo" still refers to all facts collectively;
   545 
   546 * Provers: the function blast.overloaded has been removed: all constants
   547 are regarded as potentially overloaded, which improves robustness in exchange
   548 for slight decrease in efficiency;
   549 
   550 * Provers/linorder: New generic prover for transitivity reasoning over
   551 linear orders.  Note: this prover is not efficient!
   552 
   553 * Isar: preview of problems to finish 'show' now produce an error
   554 rather than just a warning (in interactive mode);
   555 
   556 
   557 *** HOL ***
   558 
   559 * arith(_tac)
   560 
   561  - Produces a counter example if it cannot prove a goal.
   562    Note that the counter example may be spurious if the goal is not a formula
   563    of quantifier-free linear arithmetic.
   564    In ProofGeneral the counter example appears in the trace buffer.
   565 
   566  - Knows about div k and mod k where k is a numeral of type nat or int.
   567 
   568  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   569    linear arithmetic fails. This takes account of quantifiers and divisibility.
   570    Presburger arithmetic can also be called explicitly via presburger(_tac).
   571 
   572 * simp's arithmetic capabilities have been enhanced a bit: it now
   573 takes ~= in premises into account (by performing a case split);
   574 
   575 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   576 are distributed over a sum of terms;
   577 
   578 * New tactic "trans_tac" and method "trans" instantiate
   579 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   580 "<=", "<" and "=").
   581 
   582 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main
   583 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   584 
   585 * 'typedef' command has new option "open" to suppress the set
   586 definition;
   587 
   588 * functions Min and Max on finite sets have been introduced (theory
   589 Finite_Set);
   590 
   591 * attribute [symmetric] now works for relations as well; it turns
   592 (x,y) : R^-1 into (y,x) : R, and vice versa;
   593 
   594 * induct over a !!-quantified statement (say !!x1..xn):
   595   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   596 
   597 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   598 %x. None. Warning: empty_def now refers to the previously hidden definition
   599 of the empty set.
   600 
   601 * Algebra: formalization of classical algebra.  Intended as base for
   602 any algebraic development in Isabelle.  Currently covers group theory
   603 (up to Sylow's theorem) and ring theory (Universal Property of
   604 Univariate Polynomials).  Contributions welcome;
   605 
   606 * GroupTheory: deleted, since its material has been moved to Algebra;
   607 
   608 * Complex: new directory of the complex numbers with numeric constants,
   609 nonstandard complex numbers, and some complex analysis, standard and
   610 nonstandard (Jacques Fleuriot);
   611 
   612 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   613 
   614 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques
   615 Fleuriot);
   616 
   617 * Real/HahnBanach: updated and adapted to locales;
   618 
   619 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   620 Gray and Kramer);
   621 
   622 * UNITY: added the Meier-Sanders theory of progress sets;
   623 
   624 * MicroJava: bytecode verifier and lightweight bytecode verifier
   625 as abstract algorithms, instantiated to the JVM;
   626 
   627 * Bali: Java source language formalization. Type system, operational
   628 semantics, axiomatic semantics. Supported language features:
   629 classes, interfaces, objects,virtual methods, static methods,
   630 static/instance fields, arrays, access modifiers, definite
   631 assignment, exceptions.
   632 
   633 
   634 *** ZF ***
   635 
   636 * ZF/Constructible: consistency proof for AC (Gdel's constructible
   637 universe, etc.);
   638 
   639 * Main ZF: virtually all theories converted to new-style format;
   640 
   641 
   642 *** ML ***
   643 
   644 * Pure: Tactic.prove provides sane interface for internal proofs;
   645 omits the infamous "standard" operation, so this is more appropriate
   646 than prove_goalw_cterm in many situations (e.g. in simprocs);
   647 
   648 * Pure: improved error reporting of simprocs;
   649 
   650 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   651 up simprocs;
   652 
   653 
   654 *** Document preparation ***
   655 
   656 * uses \par instead of \\ for line breaks in theory text. This may
   657 shift some page breaks in large documents. To get the old behaviour
   658 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   659 
   660 * minimized dependencies of isabelle.sty and isabellesym.sty on
   661 other packages
   662 
   663 * \<euro> now needs package babel/greek instead of marvosym (which
   664 broke \Rightarrow)
   665 
   666 * normal size for \<zero>...\<nine> (uses \mathbf instead of
   667 textcomp package)
   668 
   669 
   670 
   671 New in Isabelle2002 (March 2002)
   672 --------------------------------
   673 
   674 *** Document preparation ***
   675 
   676 * greatly simplified document preparation setup, including more
   677 graceful interpretation of isatool usedir -i/-d/-D options, and more
   678 instructive isatool mkdir; users should basically be able to get
   679 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   680 users may run a separate document processing stage manually like this:
   681 "isatool usedir -D output HOL Test && isatool document Test/output";
   682 
   683 * theory dependency graph may now be incorporated into documents;
   684 isatool usedir -g true will produce session_graph.eps/.pdf for use
   685 with \includegraphics of LaTeX;
   686 
   687 * proper spacing of consecutive markup elements, especially text
   688 blocks after section headings;
   689 
   690 * support bold style (for single symbols only), input syntax is like
   691 this: "\<^bold>\<alpha>" or "\<^bold>A";
   692 
   693 * \<bullet> is now output as bold \cdot by default, which looks much
   694 better in printed text;
   695 
   696 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   697 note that these symbols are currently unavailable in Proof General /
   698 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   699 
   700 * isatool latex no longer depends on changed TEXINPUTS, instead
   701 isatool document copies the Isabelle style files to the target
   702 location;
   703 
   704 
   705 *** Isar ***
   706 
   707 * Pure/Provers: improved proof by cases and induction;
   708   - 'case' command admits impromptu naming of parameters (such as
   709     "case (Suc n)");
   710   - 'induct' method divinates rule instantiation from the inductive
   711     claim; no longer requires excessive ?P bindings for proper
   712     instantiation of cases;
   713   - 'induct' method properly enumerates all possibilities of set/type
   714     rules; as a consequence facts may be also passed through *type*
   715     rules without further ado;
   716   - 'induct' method now derives symbolic cases from the *rulified*
   717     rule (before it used to rulify cases stemming from the internal
   718     atomized version); this means that the context of a non-atomic
   719     statement becomes is included in the hypothesis, avoiding the
   720     slightly cumbersome show "PROP ?case" form;
   721   - 'induct' may now use elim-style induction rules without chaining
   722     facts, using ``missing'' premises from the goal state; this allows
   723     rules stemming from inductive sets to be applied in unstructured
   724     scripts, while still benefitting from proper handling of non-atomic
   725     statements; NB: major inductive premises need to be put first, all
   726     the rest of the goal is passed through the induction;
   727   - 'induct' proper support for mutual induction involving non-atomic
   728     rule statements (uses the new concept of simultaneous goals, see
   729     below);
   730   - append all possible rule selections, but only use the first
   731     success (no backtracking);
   732   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   733   - undeclared rule case names default to numbers 1, 2, 3, ...;
   734   - added 'print_induct_rules' (covered by help item in recent Proof
   735     General versions);
   736   - moved induct/cases attributes to Pure, methods to Provers;
   737   - generic method setup instantiated for FOL and HOL;
   738 
   739 * Pure: support multiple simultaneous goal statements, for example
   740 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   741 meta-level mechanism, this acts as if several individual goals had
   742 been stated separately; in particular common proof methods need to be
   743 repeated in order to cover all claims; note that a single elimination
   744 step is *not* sufficient to establish the two conjunctions, so this
   745 fails:
   746 
   747   assume "A & B" then have A and B ..   (*".." fails*)
   748 
   749 better use "obtain" in situations as above; alternative refer to
   750 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   751 
   752 * Pure: proper integration with ``locales''; unlike the original
   753 version by Florian Kammller, Isar locales package high-level proof
   754 contexts rather than raw logical ones (e.g. we admit to include
   755 attributes everywhere); operations on locales include merge and
   756 rename; support for implicit arguments (``structures''); simultaneous
   757 type-inference over imports and text; see also HOL/ex/Locales.thy for
   758 some examples;
   759 
   760 * Pure: the following commands have been ``localized'', supporting a
   761 target locale specification "(in name)": 'lemma', 'theorem',
   762 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   763 stored both within the locale and at the theory level (exported and
   764 qualified by the locale name);
   765 
   766 * Pure: theory goals may now be specified in ``long'' form, with
   767 ad-hoc contexts consisting of arbitrary locale elements. for example
   768 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   769 definitions may be given, too); the result is a meta-level rule with
   770 the context elements being discharged in the obvious way;
   771 
   772 * Pure: new proof command 'using' allows to augment currently used
   773 facts after a goal statement ('using' is syntactically analogous to
   774 'apply', but acts on the goal's facts only); this allows chained facts
   775 to be separated into parts given before and after a claim, as in
   776 ``from a and b have C using d and e <proof>'';
   777 
   778 * Pure: renamed "antecedent" case to "rule_context";
   779 
   780 * Pure: new 'judgment' command records explicit information about the
   781 object-logic embedding (used by several tools internally); no longer
   782 use hard-wired "Trueprop";
   783 
   784 * Pure: added 'corollary' command;
   785 
   786 * Pure: fixed 'token_translation' command;
   787 
   788 * Pure: removed obsolete 'exported' attribute;
   789 
   790 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   791 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   792 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   793 
   794 * Pure: method 'atomize' presents local goal premises as object-level
   795 statements (atomic meta-level propositions); setup controlled via
   796 rewrite rules declarations of 'atomize' attribute; example
   797 application: 'induct' method with proper rule statements in improper
   798 proof *scripts*;
   799 
   800 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   801 now consider the syntactic context of assumptions, giving a better
   802 chance to get type-inference of the arguments right (this is
   803 especially important for locales);
   804 
   805 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   806 mode;
   807 
   808 * Pure/obtain: the formal conclusion "thesis", being marked as
   809 ``internal'', may no longer be reference directly in the text;
   810 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   811 situations;
   812 
   813 * Pure: generic 'sym' attribute which declares a rule both as pure
   814 'elim?' and for the 'symmetric' operation;
   815 
   816 * Pure: marginal comments ``--'' may now occur just anywhere in the
   817 text; the fixed correlation with particular command syntax has been
   818 discontinued;
   819 
   820 * Pure: new method 'rules' is particularly well-suited for proof
   821 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   822 but often produces more compact proof terms with less detours;
   823 
   824 * Pure/Provers/classical: simplified integration with pure rule
   825 attributes and methods; the classical "intro?/elim?/dest?"
   826 declarations coincide with the pure ones; the "rule" method no longer
   827 includes classically swapped intros; "intro" and "elim" methods no
   828 longer pick rules from the context; also got rid of ML declarations
   829 AddXIs/AddXEs/AddXDs; all of this has some potential for
   830 INCOMPATIBILITY;
   831 
   832 * Provers/classical: attribute 'swapped' produces classical inversions
   833 of introduction rules;
   834 
   835 * Provers/simplifier: 'simplified' attribute may refer to explicit
   836 rules instead of full simplifier context; 'iff' attribute handles
   837 conditional rules;
   838 
   839 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   840 
   841 * HOL: 'recdef' now fails on unfinished automated proofs, use
   842 "(permissive)" option to recover old behavior;
   843 
   844 * HOL: 'inductive' no longer features separate (collective) attributes
   845 for 'intros' (was found too confusing);
   846 
   847 * HOL: properly declared induction rules less_induct and
   848 wf_induct_rule;
   849 
   850 
   851 *** HOL ***
   852 
   853 * HOL: moved over to sane numeral syntax; the new policy is as
   854 follows:
   855 
   856   - 0 and 1 are polymorphic constants, which are defined on any
   857   numeric type (nat, int, real etc.);
   858 
   859   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   860   binary representation internally;
   861 
   862   - type nat has special constructor Suc, and generally prefers Suc 0
   863   over 1::nat and Suc (Suc 0) over 2::nat;
   864 
   865 This change may cause significant problems of INCOMPATIBILITY; here
   866 are some hints on converting existing sources:
   867 
   868   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   869   entities, so expressions involving "-" (unary or binary minus) need
   870   to be spaced properly;
   871 
   872   - existing occurrences of "1" may need to be constraint "1::nat" or
   873   even replaced by Suc 0; similar for old "2";
   874 
   875   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   876 
   877   - remove all special provisions on numerals in proofs;
   878 
   879 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   880 representation (depends on bin_arith_simps in the default context);
   881 
   882 * HOL: symbolic syntax for x^2 (numeral 2);
   883 
   884 * HOL: the class of all HOL types is now called "type" rather than
   885 "term"; INCOMPATIBILITY, need to adapt references to this type class
   886 in axclass/classes, instance/arities, and (usually rare) occurrences
   887 in typings (of consts etc.); internally the class is called
   888 "HOL.type", ML programs should refer to HOLogic.typeS;
   889 
   890 * HOL/record package improvements:
   891   - new derived operations "fields" to build a partial record section,
   892     "extend" to promote a fixed record to a record scheme, and
   893     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   894     declared as simp by default;
   895   - shared operations ("more", "fields", etc.) now need to be always
   896     qualified) --- potential INCOMPATIBILITY;
   897   - removed "make_scheme" operations (use "make" with "extend") --
   898     INCOMPATIBILITY;
   899   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   900   - provides cases/induct rules for use with corresponding Isar
   901     methods (for concrete records, record schemes, concrete more
   902     parts, and schematic more parts -- in that order);
   903   - internal definitions directly based on a light-weight abstract
   904     theory of product types over typedef rather than datatype;
   905 
   906 * HOL: generic code generator for generating executable ML code from
   907 specifications; specific support for HOL constructs such as inductive
   908 datatypes and sets, as well as recursive functions; can be invoked
   909 via 'generate_code' theory section;
   910 
   911 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   912 
   913 * HOL: consolidated and renamed several theories.  In particular:
   914         Ord.thy has been absorbed into HOL.thy
   915         String.thy has been absorbed into List.thy
   916 
   917 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   918 (beware of argument permutation!);
   919 
   920 * HOL: linorder_less_split superseded by linorder_cases;
   921 
   922 * HOL/List: "nodups" renamed to "distinct";
   923 
   924 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   925 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   926   - Ex_def has changed, now need to use some_eq_ex
   927 
   928 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   929 in this (rare) case use:
   930 
   931   delSWrapper "split_all_tac"
   932   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   933 
   934 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   935 MAY FAIL;
   936 
   937 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   938 Isabelle's type classes, ^ on functions and relations has too general
   939 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   940 necessary to attach explicit type constraints;
   941 
   942 * HOL/Relation: the prefix name of the infix "O" has been changed from
   943 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   944 renamed accordingly (eg "compI" -> "rel_compI").
   945 
   946 * HOL: syntax translations now work properly with numerals and records
   947 expressions;
   948 
   949 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   950 of "lam" -- INCOMPATIBILITY;
   951 
   952 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   953 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   954 renamed "Product_Type.unit";
   955 
   956 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   957 
   958 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   959 the "cases" method);
   960 
   961 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   962 Florian Kammller);
   963 
   964 * HOL/IMP: updated and converted to new-style theory format; several
   965 parts turned into readable document, with proper Isar proof texts and
   966 some explanations (by Gerwin Klein);
   967 
   968 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   969 
   970 * HOL-Hyperreal is now a logic image;
   971 
   972 
   973 *** HOLCF ***
   974 
   975 * Isar: consts/constdefs supports mixfix syntax for continuous
   976 operations;
   977 
   978 * Isar: domain package adapted to new-style theory format, e.g. see
   979 HOLCF/ex/Dnat.thy;
   980 
   981 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   982 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   983 lift.induct_tac, always use UU instead of Undef;
   984 
   985 * HOLCF/IMP: updated and converted to new-style theory;
   986 
   987 
   988 *** ZF ***
   989 
   990 * Isar: proper integration of logic-specific tools and packages,
   991 including theory commands '(co)inductive', '(co)datatype',
   992 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   993 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   994 
   995 * theory Main no longer includes AC; for the Axiom of Choice, base
   996 your theory on Main_ZFC;
   997 
   998 * the integer library now covers quotients and remainders, with many
   999 laws relating division to addition, multiplication, etc.;
  1000 
  1001 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
  1002 typeless version of the formalism;
  1003 
  1004 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
  1005 format;
  1006 
  1007 * ZF/Induct: new directory for examples of inductive definitions,
  1008 including theory Multiset for multiset orderings; converted to
  1009 new-style theory format;
  1010 
  1011 * ZF: many new theorems about lists, ordinals, etc.;
  1012 
  1013 
  1014 *** General ***
  1015 
  1016 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
  1017 variable proof controls level of detail: 0 = no proofs (only oracle
  1018 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
  1019 also ref manual for further ML interfaces;
  1020 
  1021 * Pure/axclass: removed obsolete ML interface
  1022 goal_subclass/goal_arity;
  1023 
  1024 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
  1025 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
  1026 separate tokens, so expressions involving minus need to be spaced
  1027 properly;
  1028 
  1029 * Pure/syntax: support non-oriented infixes, using keyword "infix"
  1030 rather than "infixl" or "infixr";
  1031 
  1032 * Pure/syntax: concrete syntax for dummy type variables admits genuine
  1033 sort constraint specifications in type inference; e.g. "x::_::foo"
  1034 ensures that the type of "x" is of sort "foo" (but not necessarily a
  1035 type variable);
  1036 
  1037 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
  1038 control output of nested => (types); the default behavior is
  1039 "type_brackets";
  1040 
  1041 * Pure/syntax: builtin parse translation for "_constify" turns valued
  1042 tokens into AST constants;
  1043 
  1044 * Pure/syntax: prefer later declarations of translations and print
  1045 translation functions; potential INCOMPATIBILITY: need to reverse
  1046 multiple declarations for same syntax element constant;
  1047 
  1048 * Pure/show_hyps reset by default (in accordance to existing Isar
  1049 practice);
  1050 
  1051 * Provers/classical: renamed addaltern to addafter, addSaltern to
  1052 addSafter;
  1053 
  1054 * Provers/clasimp: ``iff'' declarations now handle conditional rules
  1055 as well;
  1056 
  1057 * system: tested support for MacOS X; should be able to get Isabelle +
  1058 Proof General to work in a plain Terminal after installing Poly/ML
  1059 (e.g. from the Isabelle distribution area) and GNU bash alone
  1060 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
  1061 support requires further installations, e.g. from
  1062 http://fink.sourceforge.net/);
  1063 
  1064 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
  1065 
  1066 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
  1067 of 40 MB), cf. ML_OPTIONS;
  1068 
  1069 * system: Proof General keywords specification is now part of the
  1070 Isabelle distribution (see etc/isar-keywords.el);
  1071 
  1072 * system: support for persistent Proof General sessions (refrain from
  1073 outdating all loaded theories on startup); user may create writable
  1074 logic images like this: ``isabelle -q HOL Test'';
  1075 
  1076 * system: smart selection of Isabelle process versus Isabelle
  1077 interface, accommodates case-insensitive file systems (e.g. HFS+); may
  1078 run both "isabelle" and "Isabelle" even if file names are badly
  1079 damaged (executable inspects the case of the first letter of its own
  1080 name); added separate "isabelle-process" and "isabelle-interface";
  1081 
  1082 * system: refrain from any attempt at filtering input streams; no
  1083 longer support ``8bit'' encoding of old isabelle font, instead proper
  1084 iso-latin characters may now be used; the related isatools
  1085 "symbolinput" and "nonascii" have disappeared as well;
  1086 
  1087 * system: removed old "xterm" interface (the print modes "xterm" and
  1088 "xterm_color" are still available for direct use in a suitable
  1089 terminal);
  1090 
  1091 
  1092 
  1093 New in Isabelle99-2 (February 2001)
  1094 -----------------------------------
  1095 
  1096 *** Overview of INCOMPATIBILITIES ***
  1097 
  1098 * HOL: please note that theories in the Library and elsewhere often use the
  1099 new-style (Isar) format; to refer to their theorems in an ML script you must
  1100 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
  1101 
  1102 * HOL: inductive package no longer splits induction rule aggressively,
  1103 but only as far as specified by the introductions given; the old
  1104 format may be recovered via ML function complete_split_rule or attribute
  1105 'split_rule (complete)';
  1106 
  1107 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
  1108 gfp_Tarski to gfp_unfold;
  1109 
  1110 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
  1111 
  1112 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
  1113 relation); infix "^^" has been renamed "``"; infix "``" has been
  1114 renamed "`"; "univalent" has been renamed "single_valued";
  1115 
  1116 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
  1117 operation;
  1118 
  1119 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
  1120 
  1121 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
  1122 
  1123 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
  1124 consequence, it is no longer monotonic wrt. the local goal context
  1125 (which is now passed through the inductive cases);
  1126 
  1127 * Document preparation: renamed standard symbols \<ll> to \<lless> and
  1128 \<gg> to \<ggreater>;
  1129 
  1130 
  1131 *** Document preparation ***
  1132 
  1133 * \isabellestyle{NAME} selects version of Isabelle output (currently
  1134 available: are "it" for near math-mode best-style output, "sl" for
  1135 slanted text style, and "tt" for plain type-writer; if no
  1136 \isabellestyle command is given, output is according to slanted
  1137 type-writer);
  1138 
  1139 * support sub/super scripts (for single symbols only), input syntax is
  1140 like this: "A\<^sup>*" or "A\<^sup>\<star>";
  1141 
  1142 * some more standard symbols; see Appendix A of the system manual for
  1143 the complete list of symbols defined in isabellesym.sty;
  1144 
  1145 * improved isabelle style files; more abstract symbol implementation
  1146 (should now use \isamath{...} and \isatext{...} in custom symbol
  1147 definitions);
  1148 
  1149 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
  1150 state; Note that presentation of goal states does not conform to
  1151 actual human-readable proof documents.  Please do not include goal
  1152 states into document output unless you really know what you are doing!
  1153 
  1154 * proper indentation of antiquoted output with proportional LaTeX
  1155 fonts;
  1156 
  1157 * no_document ML operator temporarily disables LaTeX document
  1158 generation;
  1159 
  1160 * isatool unsymbolize tunes sources for plain ASCII communication;
  1161 
  1162 
  1163 *** Isar ***
  1164 
  1165 * Pure: Isar now suffers initial goal statements to contain unbound
  1166 schematic variables (this does not conform to actual readable proof
  1167 documents, due to unpredictable outcome and non-compositional proof
  1168 checking); users who know what they are doing may use schematic goals
  1169 for Prolog-style synthesis of proven results;
  1170 
  1171 * Pure: assumption method (an implicit finishing) now handles actual
  1172 rules as well;
  1173 
  1174 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
  1175 initial goal, declare "that" only as Pure intro (only for single
  1176 steps); the "that" rule assumption may now be involved in implicit
  1177 finishing, thus ".." becomes a feasible for trivial obtains;
  1178 
  1179 * Pure: default proof step now includes 'intro_classes'; thus trivial
  1180 instance proofs may be performed by "..";
  1181 
  1182 * Pure: ?thesis / ?this / "..." now work for pure meta-level
  1183 statements as well;
  1184 
  1185 * Pure: more robust selection of calculational rules;
  1186 
  1187 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
  1188 rule (as well as the assumption rule);
  1189 
  1190 * Pure: 'thm_deps' command visualizes dependencies of theorems and
  1191 lemmas, using the graph browser tool;
  1192 
  1193 * Pure: predict failure of "show" in interactive mode;
  1194 
  1195 * Pure: 'thms_containing' now takes actual terms as arguments;
  1196 
  1197 * HOL: improved method 'induct' --- now handles non-atomic goals
  1198 (potential INCOMPATIBILITY); tuned error handling;
  1199 
  1200 * HOL: cases and induct rules now provide explicit hints about the
  1201 number of facts to be consumed (0 for "type" and 1 for "set" rules);
  1202 any remaining facts are inserted into the goal verbatim;
  1203 
  1204 * HOL: local contexts (aka cases) may now contain term bindings as
  1205 well; the 'cases' and 'induct' methods new provide a ?case binding for
  1206 the result to be shown in each case;
  1207 
  1208 * HOL: added 'recdef_tc' command;
  1209 
  1210 * isatool convert assists in eliminating legacy ML scripts;
  1211 
  1212 
  1213 *** HOL ***
  1214 
  1215 * HOL/Library: a collection of generic theories to be used together
  1216 with main HOL; the theory loader path already includes this directory
  1217 by default; the following existing theories have been moved here:
  1218 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
  1219 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
  1220 
  1221 * HOL/Unix: "Some aspects of Unix file-system security", a typical
  1222 modelling and verification task performed in Isabelle/HOL +
  1223 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
  1224 
  1225 * HOL/Algebra: special summation operator SUM no longer exists, it has
  1226 been replaced by setsum; infix 'assoc' now has priority 50 (like
  1227 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
  1228 'domain', this makes the theory consistent with mathematical
  1229 literature;
  1230 
  1231 * HOL basics: added overloaded operations "inverse" and "divide"
  1232 (infix "/"), syntax for generic "abs" operation, generic summation
  1233 operator \<Sum>;
  1234 
  1235 * HOL/typedef: simplified package, provide more useful rules (see also
  1236 HOL/subset.thy);
  1237 
  1238 * HOL/datatype: induction rule for arbitrarily branching datatypes is
  1239 now expressed as a proper nested rule (old-style tactic scripts may
  1240 require atomize_strip_tac to cope with non-atomic premises);
  1241 
  1242 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
  1243 to "split_conv" (old name still available for compatibility);
  1244 
  1245 * HOL: improved concrete syntax for strings (e.g. allows translation
  1246 rules with string literals);
  1247 
  1248 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
  1249  and Fleuriot's mechanization of analysis, including the transcendental
  1250  functions for the reals;
  1251 
  1252 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
  1253 
  1254 
  1255 *** CTT ***
  1256 
  1257 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
  1258 "lam" is displayed as TWO lambda-symbols
  1259 
  1260 * CTT: theory Main now available, containing everything (that is, Bool
  1261 and Arith);
  1262 
  1263 
  1264 *** General ***
  1265 
  1266 * Pure: the Simplifier has been implemented properly as a derived rule
  1267 outside of the actual kernel (at last!); the overall performance
  1268 penalty in practical applications is about 50%, while reliability of
  1269 the Isabelle inference kernel has been greatly improved;
  1270 
  1271 * print modes "brackets" and "no_brackets" control output of nested =>
  1272 (types) and ==> (props); the default behaviour is "brackets";
  1273 
  1274 * Provers: fast_tac (and friends) now handle actual object-logic rules
  1275 as assumptions as well;
  1276 
  1277 * system: support Poly/ML 4.0;
  1278 
  1279 * system: isatool install handles KDE version 1 or 2;
  1280 
  1281 
  1282 
  1283 New in Isabelle99-1 (October 2000)
  1284 ----------------------------------
  1285 
  1286 *** Overview of INCOMPATIBILITIES ***
  1287 
  1288 * HOL: simplification of natural numbers is much changed; to partly
  1289 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
  1290 issue the following ML commands:
  1291 
  1292   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
  1293   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
  1294 
  1295 * HOL: simplification no longer dives into case-expressions; this is
  1296 controlled by "t.weak_case_cong" for each datatype t;
  1297 
  1298 * HOL: nat_less_induct renamed to less_induct;
  1299 
  1300 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
  1301 fixsome to patch .thy and .ML sources automatically;
  1302 
  1303   select_equality  -> some_equality
  1304   select_eq_Ex     -> some_eq_ex
  1305   selectI2EX       -> someI2_ex
  1306   selectI2         -> someI2
  1307   selectI          -> someI
  1308   select1_equality -> some1_equality
  1309   Eps_sym_eq       -> some_sym_eq_trivial
  1310   Eps_eq           -> some_eq_trivial
  1311 
  1312 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
  1313 
  1314 * HOL: removed obsolete theorem binding expand_if (refer to split_if
  1315 instead);
  1316 
  1317 * HOL: the recursion equations generated by 'recdef' are now called
  1318 f.simps instead of f.rules;
  1319 
  1320 * HOL: qed_spec_mp now also handles bounded ALL as well;
  1321 
  1322 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  1323 sometimes be needed;
  1324 
  1325 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  1326 
  1327 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  1328 
  1329 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  1330 product is now "<*>" instead of "Times"; the lexicographic product is
  1331 now "<*lex*>" instead of "**";
  1332 
  1333 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  1334 of main HOL, but was unused); better use HOL's datatype package;
  1335 
  1336 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  1337 the old syntax may be recovered as follows:
  1338 
  1339   syntax (symbols)
  1340     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  1341       (infixl "\\<oplus>" 100)
  1342 
  1343 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1344 
  1345 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1346 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1347 internally;
  1348 
  1349 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1350 changed from A/r to A//r;
  1351 
  1352 * ZF: new treatment of arithmetic (nat & int) may break some old
  1353 proofs;
  1354 
  1355 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1356 rulify -> rule_format, elimify -> elim_format, ...);
  1357 
  1358 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1359 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1360 should have to change intro!! to intro? only); replaced "delrule" by
  1361 "rule del";
  1362 
  1363 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1364 
  1365 * Provers: strengthened force_tac by using new first_best_tac;
  1366 
  1367 * LaTeX document preparation: several changes of isabelle.sty (see
  1368 lib/texinputs);
  1369 
  1370 
  1371 *** Document preparation ***
  1372 
  1373 * formal comments (text blocks etc.) in new-style theories may now
  1374 contain antiquotations of thm/prop/term/typ/text to be presented
  1375 according to latex print mode; concrete syntax is like this:
  1376 @{term[show_types] "f(x) = a + x"};
  1377 
  1378 * isatool mkdir provides easy setup of Isabelle session directories,
  1379 including proper document sources;
  1380 
  1381 * generated LaTeX sources are now deleted after successful run
  1382 (isatool document -c); may retain a copy somewhere else via -D option
  1383 of isatool usedir;
  1384 
  1385 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1386 style files, achieving self-contained LaTeX sources and simplifying
  1387 LaTeX debugging;
  1388 
  1389 * old-style theories now produce (crude) LaTeX output as well;
  1390 
  1391 * browser info session directories are now self-contained (may be put
  1392 on WWW server seperately); improved graphs of nested sessions; removed
  1393 graph for 'all sessions';
  1394 
  1395 * several improvements in isabelle style files; \isabellestyle{it}
  1396 produces fake math mode output; \isamarkupheader is now \section by
  1397 default; see lib/texinputs/isabelle.sty etc.;
  1398 
  1399 
  1400 *** Isar ***
  1401 
  1402 * Isar/Pure: local results and corresponding term bindings are now
  1403 subject to Hindley-Milner polymorphism (similar to ML); this
  1404 accommodates incremental type-inference very nicely;
  1405 
  1406 * Isar/Pure: new derived language element 'obtain' supports
  1407 generalized existence reasoning;
  1408 
  1409 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1410 support accumulation of results, without applying any rules yet;
  1411 useful to collect intermediate results without explicit name
  1412 references, and for use with transitivity rules with more than 2
  1413 premises;
  1414 
  1415 * Isar/Pure: scalable support for case-analysis type proofs: new
  1416 'case' language element refers to local contexts symbolically, as
  1417 produced by certain proof methods; internally, case names are attached
  1418 to theorems as "tags";
  1419 
  1420 * Isar/Pure: theory command 'hide' removes declarations from
  1421 class/type/const name spaces;
  1422 
  1423 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1424 indicate potential overloading;
  1425 
  1426 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1427 
  1428 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1429 "{a,b,c}" instead of {a,b,c};
  1430 
  1431 * Isar/Pure now provides its own version of intro/elim/dest
  1432 attributes; useful for building new logics, but beware of confusion
  1433 with the version in Provers/classical;
  1434 
  1435 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1436 case name 'antecedent';
  1437 
  1438 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1439 to the current context is now done automatically);
  1440 
  1441 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1442 for definining proof methods in ML;
  1443 
  1444 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1445 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1446 most cases, one should have to change intro!! to intro? only);
  1447 replaced "delrule" by "rule del";
  1448 
  1449 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1450 'symmetric' attribute (the latter supercedes [RS sym]);
  1451 
  1452 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1453 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1454 well (including splits);
  1455 
  1456 * Isar/Provers: Simplifier and Classical methods now support all kind
  1457 of modifiers used in the past, including 'cong', 'iff', etc.
  1458 
  1459 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1460 of Simplifier and Classical reasoner);
  1461 
  1462 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1463 now support named cases; major packages (inductive, datatype, primrec,
  1464 recdef) support case names and properly name parameters;
  1465 
  1466 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1467 monotonicity conditions are extracted to be proven at end of
  1468 calculations;
  1469 
  1470 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1471 method anyway;
  1472 
  1473 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1474 split_if split_if_asm; datatype package provides theorems foo.splits =
  1475 foo.split foo.split_asm for each datatype;
  1476 
  1477 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1478 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1479 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1480 use "(cases (simplified))" method in proper proof texts);
  1481 
  1482 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1483 
  1484 * Isar: names of theorems etc. may be natural numbers as well;
  1485 
  1486 * Isar: 'pr' command: optional arguments for goals_limit and
  1487 ProofContext.prems_limit; no longer prints theory contexts, but only
  1488 proof states;
  1489 
  1490 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1491 additional print modes to be specified; e.g. "pr(latex)" will print
  1492 proof state according to the Isabelle LaTeX style;
  1493 
  1494 * Isar: improved support for emulating tactic scripts, including proof
  1495 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1496 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1497 (for HOL datatypes);
  1498 
  1499 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1500 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1501 'proof method scripts' have to be in depth-first order;
  1502 
  1503 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1504 
  1505 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1506 should instead use individual commands for printing items
  1507 (print_commands, print_methods etc.);
  1508 
  1509 * Isar: added 'nothing' --- the empty list of theorems;
  1510 
  1511 
  1512 *** HOL ***
  1513 
  1514 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1515 corresponding virtual machine and a specification of its bytecode
  1516 verifier and a lightweight bytecode verifier, including proofs of
  1517 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1518 Cornelia Pusch (see also the homepage of project Bali at
  1519 http://isabelle.in.tum.de/Bali/);
  1520 
  1521 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1522 Clemens Ballarin;
  1523 
  1524 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1525 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1526 Rasmussen;
  1527 
  1528 * HOL/Lattice: fundamental concepts of lattice theory and order
  1529 structures, including duals, properties of bounds versus algebraic
  1530 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1531 Theorem for complete lattices etc.; may also serve as a demonstration
  1532 for abstract algebraic reasoning using axiomatic type classes, and
  1533 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1534 
  1535 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1536 von Oheimb;
  1537 
  1538 * HOL/IMPP: extension of IMP with local variables and mutually
  1539 recursive procedures, by David von Oheimb;
  1540 
  1541 * HOL/Lambda: converted into new-style theory and document;
  1542 
  1543 * HOL/ex/Multiquote: example of multiple nested quotations and
  1544 anti-quotations -- basically a generalized version of de-Bruijn
  1545 representation; very useful in avoiding lifting of operations;
  1546 
  1547 * HOL/record: added general record equality rule to simpset; fixed
  1548 select-update simplification procedure to handle extended records as
  1549 well; admit "r" as field name;
  1550 
  1551 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1552 other numeric types and also as the identity of groups, rings, etc.;
  1553 
  1554 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1555 Types nat and int belong to this axclass;
  1556 
  1557 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1558    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1559    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1560   two terms #m*u and #n*u are replaced by #(m+n)*u
  1561     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1562   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1563     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1564 
  1565 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1566 powerful prover for predicate logic but knows nothing of clasets; see
  1567 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1568 
  1569 * HOL: new version of "case_tac" subsumes both boolean case split and
  1570 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1571 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1572 
  1573 * HOL: simplification no longer dives into case-expressions: only the
  1574 selector expression is simplified, but not the remaining arms; to
  1575 enable full simplification of case-expressions for datatype t, you may
  1576 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1577 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1578 
  1579 * HOL/recdef: the recursion equations generated by 'recdef' for
  1580 function 'f' are now called f.simps instead of f.rules; if all
  1581 termination conditions are proved automatically, these simplification
  1582 rules are added to the simpset, as in primrec; rules may be named
  1583 individually as well, resulting in a separate list of theorems for
  1584 each equation;
  1585 
  1586 * HOL/While is a new theory that provides a while-combinator. It
  1587 permits the definition of tail-recursive functions without the
  1588 provision of a termination measure. The latter is necessary once the
  1589 invariant proof rule for while is applied.
  1590 
  1591 * HOL: new (overloaded) notation for the set of elements below/above
  1592 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1593 
  1594 * HOL: theorems impI, allI, ballI bound as "strip";
  1595 
  1596 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1597 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1598 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1599 
  1600 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1601 
  1602 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1603 main HOL, but was unused);
  1604 
  1605 * HOL: fewer consts declared as global (e.g. have to refer to
  1606 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1607 
  1608 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1609 in case of overlap with user translations (e.g. judgements over
  1610 tuples); (note that the underlying logical represenation is still
  1611 bogus);
  1612 
  1613 
  1614 *** ZF ***
  1615 
  1616 * ZF: simplification automatically cancels common terms in arithmetic
  1617 expressions over nat and int;
  1618 
  1619 * ZF: new treatment of nat to minimize type-checking: all operators
  1620 coerce their operands to a natural number using the function natify,
  1621 making the algebraic laws unconditional;
  1622 
  1623 * ZF: as above, for int: operators coerce their operands to an integer
  1624 using the function intify;
  1625 
  1626 * ZF: the integer library now contains many of the usual laws for the
  1627 orderings, including $<=, and monotonicity laws for $+ and $*;
  1628 
  1629 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1630 simplification;
  1631 
  1632 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1633 to the simplifier and classical reasoner simultaneously;
  1634 
  1635 
  1636 *** General ***
  1637 
  1638 * Provers: blast_tac now handles actual object-logic rules as
  1639 assumptions; note that auto_tac uses blast_tac internally as well;
  1640 
  1641 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1642 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1643 
  1644 * Provers: delrules now handles destruct rules as well (no longer need
  1645 explicit make_elim);
  1646 
  1647 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1648   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1649 use instead the strong form,
  1650   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1651 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1652 from destruct-rules;
  1653 
  1654 * Provers: Simplifier.easy_setup provides a fast path to basic
  1655 Simplifier setup for new object-logics;
  1656 
  1657 * Pure: AST translation rules no longer require constant head on LHS;
  1658 
  1659 * Pure: improved name spaces: ambiguous output is qualified; support
  1660 for hiding of names;
  1661 
  1662 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1663 XSYMBOL_HOME; no longer need to do manual configuration in most
  1664 situations;
  1665 
  1666 * system: compression of ML heaps images may now be controlled via -c
  1667 option of isabelle and isatool usedir (currently only observed by
  1668 Poly/ML);
  1669 
  1670 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1671 useful for remote X11);
  1672 
  1673 * system: provide TAGS file for Isabelle sources;
  1674 
  1675 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1676 order;
  1677 
  1678 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1679 timing flag supersedes proof_timing and Toplevel.trace;
  1680 
  1681 * ML: new combinators |>> and |>>> for incremental transformations
  1682 with secondary results (e.g. certain theory extensions):
  1683 
  1684 * ML: PureThy.add_defs gets additional argument to indicate potential
  1685 overloading (usually false);
  1686 
  1687 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1688 results;
  1689 
  1690 
  1691 
  1692 New in Isabelle99 (October 1999)
  1693 --------------------------------
  1694 
  1695 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1696 
  1697 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1698 are no longer simplified.  (This allows the simplifier to unfold recursive
  1699 functional programs.)  To restore the old behaviour, declare
  1700 
  1701     Delcongs [if_weak_cong];
  1702 
  1703 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1704 complement;
  1705 
  1706 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1707 
  1708 * HOL/datatype: mutual_induct_tac no longer exists --
  1709   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1710 
  1711 * HOL/typedef: fixed type inference for representing set; type
  1712 arguments now have to occur explicitly on the rhs as type constraints;
  1713 
  1714 * ZF: The con_defs part of an inductive definition may no longer refer
  1715 to constants declared in the same theory;
  1716 
  1717 * HOL, ZF: the function mk_cases, generated by the inductive
  1718 definition package, has lost an argument.  To simplify its result, it
  1719 uses the default simpset instead of a supplied list of theorems.
  1720 
  1721 * HOL/List: the constructors of type list are now Nil and Cons;
  1722 
  1723 * Simplifier: the type of the infix ML functions
  1724         setSSolver addSSolver setSolver addSolver
  1725 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1726 for packaging solvers. A solver is created via
  1727         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1728 where the string argument is only a comment.
  1729 
  1730 
  1731 *** Proof tools ***
  1732 
  1733 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1734 decision procedure for linear arithmetic. Currently it is used for
  1735 types `nat', `int', and `real' in HOL (see below); it can, should and
  1736 will be instantiated for other types and logics as well.
  1737 
  1738 * The simplifier now accepts rewrite rules with flexible heads, eg
  1739      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1740   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1741   matching.
  1742 
  1743 
  1744 *** General ***
  1745 
  1746 * New Isabelle/Isar subsystem provides an alternative to traditional
  1747 tactical theorem proving; together with the ProofGeneral/isar user
  1748 interface it offers an interactive environment for developing human
  1749 readable proof documents (Isar == Intelligible semi-automated
  1750 reasoning); for further information see isatool doc isar-ref,
  1751 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1752 
  1753 * improved and simplified presentation of theories: better HTML markup
  1754 (including colors), graph views in several sizes; isatool usedir now
  1755 provides a proper interface for user theories (via -P option); actual
  1756 document preparation based on (PDF)LaTeX is available as well (for
  1757 new-style theories only); see isatool doc system for more information;
  1758 
  1759 * native support for Proof General, both for classic Isabelle and
  1760 Isabelle/Isar;
  1761 
  1762 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1763 using the graph browser tool;
  1764 
  1765 * Isabelle manuals now also available as PDF;
  1766 
  1767 * theory loader rewritten from scratch (may not be fully
  1768 bug-compatible); old loadpath variable has been replaced by show_path,
  1769 add_path, del_path, reset_path functions; new operations such as
  1770 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1771 isatool doc ref);
  1772 
  1773 * improved isatool install: option -k creates KDE application icon,
  1774 option -p DIR installs standalone binaries;
  1775 
  1776 * added ML_PLATFORM setting (useful for cross-platform installations);
  1777 more robust handling of platform specific ML images for SML/NJ;
  1778 
  1779 * the settings environment is now statically scoped, i.e. it is never
  1780 created again in sub-processes invoked from isabelle, isatool, or
  1781 Isabelle;
  1782 
  1783 * path element specification '~~' refers to '$ISABELLE_HOME';
  1784 
  1785 * in locales, the "assumes" and "defines" parts may be omitted if
  1786 empty;
  1787 
  1788 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1789 long arrows);
  1790 
  1791 * new print_mode "HTML";
  1792 
  1793 * new flag show_tags controls display of tags of theorems (which are
  1794 basically just comments that may be attached by some tools);
  1795 
  1796 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1797 mode and goal output format:
  1798 
  1799 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1800 244c244
  1801 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1802 ---
  1803 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1804 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1805 181c181
  1806 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1807 ---
  1808 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1809 
  1810 * function bind_thms stores lists of theorems (cf. bind_thm);
  1811 
  1812 * new shorthand tactics ftac, eatac, datac, fatac;
  1813 
  1814 * qed (and friends) now accept "" as result name; in that case the
  1815 theorem is not stored, but proper checks and presentation of the
  1816 result still apply;
  1817 
  1818 * theorem database now also indexes constants "Trueprop", "all",
  1819 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1820 
  1821 
  1822 *** HOL ***
  1823 
  1824 ** HOL arithmetic **
  1825 
  1826 * There are now decision procedures for linear arithmetic over nat and
  1827 int:
  1828 
  1829 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1830 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1831 are treated as atomic; subformulae not involving type `nat' or `int'
  1832 are ignored; quantified subformulae are ignored unless they are
  1833 positive universal or negative existential. The tactic has to be
  1834 invoked by hand and can be a little bit slow. In particular, the
  1835 running time is exponential in the number of occurrences of `min' and
  1836 `max', and `-' on `nat'.
  1837 
  1838 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1839 (negated) (in)equalities among the premises and the conclusion into
  1840 account (i.e. no compound formulae) and does not know about `min' and
  1841 `max', and `-' on `nat'. It is fast and is used automatically by the
  1842 simplifier.
  1843 
  1844 NB: At the moment, these decision procedures do not cope with mixed
  1845 nat/int formulae where the two parts interact, such as `m < n ==>
  1846 int(m) < int(n)'.
  1847 
  1848 * HOL/Numeral provides a generic theory of numerals (encoded
  1849 efficiently as bit strings); setup for types nat/int/real is in place;
  1850 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1851 int, existing theories and proof scripts may require a few additional
  1852 type constraints;
  1853 
  1854 * integer division and remainder can now be performed on constant
  1855 arguments;
  1856 
  1857 * many properties of integer multiplication, division and remainder
  1858 are now available;
  1859 
  1860 * An interface to the Stanford Validity Checker (SVC) is available through the
  1861 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1862 are proved automatically.  SVC must be installed separately, and its results
  1863 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1864 invocation of the underlying oracle).  For SVC see
  1865   http://verify.stanford.edu/SVC
  1866 
  1867 * IsaMakefile: the HOL-Real target now builds an actual image;
  1868 
  1869 
  1870 ** HOL misc **
  1871 
  1872 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1873 (in Isabelle/Isar) -- by Gertrud Bauer;
  1874 
  1875 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1876 analysis for assembly languages with subtypes;
  1877 
  1878 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1879 -- avoids syntactic ambiguities and treats state, transition, and
  1880 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1881 changed syntax and (many) tactics;
  1882 
  1883 * HOL/inductive: Now also handles more general introduction rules such
  1884   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1885   theorems are now maintained within the theory (maintained via the
  1886   "mono" attribute);
  1887 
  1888 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1889   (using function types) such as
  1890 
  1891   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1892 
  1893 * HOL/record: record_simproc (part of the default simpset) takes care
  1894 of selectors applied to updated records; record_split_tac is no longer
  1895 part of the default claset; update_defs may now be removed from the
  1896 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1897 
  1898   claset_ref () := claset() addSWrapper record_split_wrapper;
  1899   Delsimprocs [record_simproc]
  1900 
  1901 * HOL/typedef: fixed type inference for representing set; type
  1902 arguments now have to occur explicitly on the rhs as type constraints;
  1903 
  1904 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1905 names rather than an ML expression;
  1906 
  1907 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1908 supplied later.  Program schemes can be defined, such as
  1909     "While B C s = (if B s then While B C (C s) else s)"
  1910 where the well-founded relation can be chosen after B and C have been given.
  1911 
  1912 * HOL/List: the constructors of type list are now Nil and Cons;
  1913 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1914 course, ML tools referring to List.list.op # etc. have to be adapted;
  1915 
  1916 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1917 disabled by default; run isabelle with option -m HOL to get back to
  1918 the original Gordon/HOL-style output;
  1919 
  1920 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1921 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1922 
  1923 * HOL basic syntax simplified (more orthogonal): all variants of
  1924 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1925 Eps operator is provided as well: "SOME x. P[x]";
  1926 
  1927 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1928 
  1929 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1930 thus available for user theories;
  1931 
  1932 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1933 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1934 time;
  1935 
  1936 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1937 several times and then mp;
  1938 
  1939 
  1940 *** LK ***
  1941 
  1942 * the notation <<...>> is now available as a notation for sequences of
  1943 formulas;
  1944 
  1945 * the simplifier is now installed
  1946 
  1947 * the axiom system has been generalized (thanks to Soren Heilmann)
  1948 
  1949 * the classical reasoner now has a default rule database
  1950 
  1951 
  1952 *** ZF ***
  1953 
  1954 * new primrec section allows primitive recursive functions to be given
  1955 directly (as in HOL) over datatypes and the natural numbers;
  1956 
  1957 * new tactics induct_tac and exhaust_tac for induction (or case
  1958 analysis) over datatypes and the natural numbers;
  1959 
  1960 * the datatype declaration of type T now defines the recursor T_rec;
  1961 
  1962 * simplification automatically does freeness reasoning for datatype
  1963 constructors;
  1964 
  1965 * automatic type-inference, with AddTCs command to insert new
  1966 type-checking rules;
  1967 
  1968 * datatype introduction rules are now added as Safe Introduction rules
  1969 to the claset;
  1970 
  1971 * the syntax "if P then x else y" is now available in addition to
  1972 if(P,x,y);
  1973 
  1974 
  1975 *** Internal programming interfaces ***
  1976 
  1977 * tuned simplifier trace output; new flag debug_simp;
  1978 
  1979 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1980 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1981 
  1982 * AxClass.axclass_tac lost the theory argument;
  1983 
  1984 * tuned current_goals_markers semantics: begin / end goal avoids
  1985 printing empty lines;
  1986 
  1987 * removed prs and prs_fn hook, which was broken because it did not
  1988 include \n in its semantics, forcing writeln to add one
  1989 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1990 string -> unit if you really want to output text without newline;
  1991 
  1992 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1993 plain output, interface builders may have to enable 'isabelle_font'
  1994 mode to get Isabelle font glyphs as before;
  1995 
  1996 * refined token_translation interface; INCOMPATIBILITY: output length
  1997 now of type real instead of int;
  1998 
  1999 * theory loader actions may be traced via new ThyInfo.add_hook
  2000 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  2001 your own database of information attached to *whole* theories -- as
  2002 opposed to intra-theory data slots offered via TheoryDataFun;
  2003 
  2004 * proper handling of dangling sort hypotheses (at last!);
  2005 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  2006 extra sort hypotheses that can be witnessed from the type signature;
  2007 the force_strip_shyps flag is gone, any remaining shyps are simply
  2008 left in the theorem (with a warning issued by strip_shyps_warning);
  2009 
  2010 
  2011 
  2012 New in Isabelle98-1 (October 1998)
  2013 ----------------------------------
  2014 
  2015 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2016 
  2017 * several changes of automated proof tools;
  2018 
  2019 * HOL: major changes to the inductive and datatype packages, including
  2020 some minor incompatibilities of theory syntax;
  2021 
  2022 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  2023 called `inj_on';
  2024 
  2025 * HOL: removed duplicate thms in Arith:
  2026   less_imp_add_less  should be replaced by  trans_less_add1
  2027   le_imp_add_le      should be replaced by  trans_le_add1
  2028 
  2029 * HOL: unary minus is now overloaded (new type constraints may be
  2030 required);
  2031 
  2032 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  2033 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  2034 now taken as an integer constant.
  2035 
  2036 * Pure: ML function 'theory_of' renamed to 'theory';
  2037 
  2038 
  2039 *** Proof tools ***
  2040 
  2041 * Simplifier:
  2042   1. Asm_full_simp_tac is now more aggressive.
  2043      1. It will sometimes reorient premises if that increases their power to
  2044         simplify.
  2045      2. It does no longer proceed strictly from left to right but may also
  2046         rotate premises to achieve further simplification.
  2047      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  2048      old Asm_full_simp_tac in that it does not rotate premises.
  2049   2. The simplifier now knows a little bit about nat-arithmetic.
  2050 
  2051 * Classical reasoner: wrapper mechanism for the classical reasoner now
  2052 allows for selected deletion of wrappers, by introduction of names for
  2053 wrapper functionals.  This implies that addbefore, addSbefore,
  2054 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  2055 and that adding two tactics with the same name overwrites the first
  2056 one (emitting a warning).
  2057   type wrapper = (int -> tactic) -> (int -> tactic)
  2058   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  2059   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  2060   delWrapper, delSWrapper: claset *  string            -> claset
  2061   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  2062 
  2063 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  2064 semantics; addbefore now affects only the unsafe part of step_tac
  2065 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  2066 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  2067 by Force_tac;
  2068 
  2069 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  2070 compWrapper; added safe wrapper (and access functions for it);
  2071 
  2072 * HOL/split_all_tac is now much faster and fails if there is nothing
  2073 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  2074 and the names of the automatically generated variables have changed.
  2075 split_all_tac has moved within claset() from unsafe wrappers to safe
  2076 wrappers, which means that !!-bound variables are split much more
  2077 aggressively, and safe_tac and clarify_tac now split such variables.
  2078 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  2079 Note: the same holds for record_split_tac, which does the job of
  2080 split_all_tac for record fields.
  2081 
  2082 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  2083 permanently to the default simpset using Addsplits just like
  2084 Addsimps. They can be removed via Delsplits just like
  2085 Delsimps. Lower-case versions are also available.
  2086 
  2087 * HOL/Simplifier: The rule split_if is now part of the default
  2088 simpset. This means that the simplifier will eliminate all occurrences
  2089 of if-then-else in the conclusion of a goal. To prevent this, you can
  2090 either remove split_if completely from the default simpset by
  2091 `Delsplits [split_if]' or remove it in a specific call of the
  2092 simplifier using `... delsplits [split_if]'.  You can also add/delete
  2093 other case splitting rules to/from the default simpset: every datatype
  2094 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  2095 t is the name of the datatype).
  2096 
  2097 * Classical reasoner / Simplifier combination: new force_tac (and
  2098 derivatives Force_tac, force) combines rewriting and classical
  2099 reasoning (and whatever other tools) similarly to auto_tac, but is
  2100 aimed to solve the given subgoal completely.
  2101 
  2102 
  2103 *** General ***
  2104 
  2105 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  2106 and `goalw': the theory is no longer needed as an explicit argument -
  2107 the current theory context is used; assumptions are no longer returned
  2108 at the ML-level unless one of them starts with ==> or !!; it is
  2109 recommended to convert to these new commands using isatool fixgoal
  2110 (backup your sources first!);
  2111 
  2112 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  2113 the current theory context, and 'theory' to lookup stored theories;
  2114 
  2115 * new theory section 'locale' for declaring constants, assumptions and
  2116 definitions that have local scope;
  2117 
  2118 * new theory section 'nonterminals' for purely syntactic types;
  2119 
  2120 * new theory section 'setup' for generic ML setup functions
  2121 (e.g. package initialization);
  2122 
  2123 * the distribution now includes Isabelle icons: see
  2124 lib/logo/isabelle-{small,tiny}.xpm;
  2125 
  2126 * isatool install - install binaries with absolute references to
  2127 ISABELLE_HOME/bin;
  2128 
  2129 * isatool logo -- create instances of the Isabelle logo (as EPS);
  2130 
  2131 * print mode 'emacs' reserved for Isamode;
  2132 
  2133 * support multiple print (ast) translations per constant name;
  2134 
  2135 * theorems involving oracles are now printed with a suffixed [!];
  2136 
  2137 
  2138 *** HOL ***
  2139 
  2140 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  2141 
  2142 * HOL/inductive package reorganized and improved: now supports mutual
  2143 definitions such as
  2144 
  2145   inductive EVEN ODD
  2146     intrs
  2147       null "0 : EVEN"
  2148       oddI "n : EVEN ==> Suc n : ODD"
  2149       evenI "n : ODD ==> Suc n : EVEN"
  2150 
  2151 new theorem list "elims" contains an elimination rule for each of the
  2152 recursive sets; inductive definitions now handle disjunctive premises
  2153 correctly (also ZF);
  2154 
  2155 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  2156 "mutual_induct" no longer exists - the induction rule is always
  2157 contained in "induct";
  2158 
  2159 
  2160 * HOL/datatype package re-implemented and greatly improved: now
  2161 supports mutually recursive datatypes such as
  2162 
  2163   datatype
  2164     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  2165             | SUM ('a aexp) ('a aexp)
  2166             | DIFF ('a aexp) ('a aexp)
  2167             | NUM 'a
  2168   and
  2169     'a bexp = LESS ('a aexp) ('a aexp)
  2170             | AND ('a bexp) ('a bexp)
  2171             | OR ('a bexp) ('a bexp)
  2172 
  2173 as well as indirectly recursive datatypes such as
  2174 
  2175   datatype
  2176     ('a, 'b) term = Var 'a
  2177                   | App 'b ((('a, 'b) term) list)
  2178 
  2179 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  2180 induction on mutually / indirectly recursive datatypes.
  2181 
  2182 Primrec equations are now stored in theory and can be accessed via
  2183 <function_name>.simps.
  2184 
  2185 INCOMPATIBILITIES:
  2186 
  2187   - Theories using datatypes must now have theory Datatype as an
  2188     ancestor.
  2189   - The specific <typename>.induct_tac no longer exists - use the
  2190     generic induct_tac instead.
  2191   - natE has been renamed to nat.exhaust - use exhaust_tac
  2192     instead of res_inst_tac ... natE. Note that the variable
  2193     names in nat.exhaust differ from the names in natE, this
  2194     may cause some "fragile" proofs to fail.
  2195   - The theorems split_<typename>_case and split_<typename>_case_asm
  2196     have been renamed to <typename>.split and <typename>.split_asm.
  2197   - Since default sorts of type variables are now handled correctly,
  2198     some datatype definitions may have to be annotated with explicit
  2199     sort constraints.
  2200   - Primrec definitions no longer require function name and type
  2201     of recursive argument.
  2202 
  2203 Consider using isatool fixdatatype to adapt your theories and proof
  2204 scripts to the new package (backup your sources first!).
  2205 
  2206 
  2207 * HOL/record package: considerably improved implementation; now
  2208 includes concrete syntax for record types, terms, updates; theorems
  2209 for surjective pairing and splitting !!-bound record variables; proof
  2210 support is as follows:
  2211 
  2212   1) standard conversions (selectors or updates applied to record
  2213 constructor terms) are part of the standard simpset;
  2214 
  2215   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  2216 made part of standard simpset and claset via addIffs;
  2217 
  2218   3) a tactic for record field splitting (record_split_tac) is part of
  2219 the standard claset (addSWrapper);
  2220 
  2221 To get a better idea about these rules you may retrieve them via
  2222 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  2223 the name of your record type.
  2224 
  2225 The split tactic 3) conceptually simplifies by the following rule:
  2226 
  2227   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  2228 
  2229 Thus any record variable that is bound by meta-all will automatically
  2230 blow up into some record constructor term, consequently the
  2231 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  2232 solve record problems automatically.
  2233 
  2234 
  2235 * reorganized the main HOL image: HOL/Integ and String loaded by
  2236 default; theory Main includes everything;
  2237 
  2238 * automatic simplification of integer sums and comparisons, using cancellation;
  2239 
  2240 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  2241 
  2242 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  2243 
  2244 * many new identities for unions, intersections, set difference, etc.;
  2245 
  2246 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  2247 called split_if, split_split, split_sum_case and split_nat_case (to go
  2248 with add/delsplits);
  2249 
  2250 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  2251 (?x::unit) = (); this is made part of the default simpset, which COULD
  2252 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  2253 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  2254 unit_abs_eta_conv is added in order to counter the effect of
  2255 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  2256 %u.f();
  2257 
  2258 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  2259 makes more sense);
  2260 
  2261 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2262   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2263   disjointness reasoning but breaking a few old proofs.
  2264 
  2265 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  2266 to 'converse' from 'inverse' (for compatibility with ZF and some
  2267 literature);
  2268 
  2269 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  2270 the well-founded relation;
  2271 
  2272 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  2273     Compl A.  The "Compl" syntax remains available as input syntax for this
  2274     release ONLY.
  2275 
  2276 * HOL/Update: new theory of function updates:
  2277     f(a:=b) == %x. if x=a then b else f x
  2278 may also be iterated as in f(a:=b,c:=d,...);
  2279 
  2280 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  2281 
  2282 * HOL/List:
  2283   - new function list_update written xs[i:=v] that updates the i-th
  2284     list position. May also be iterated as in xs[i:=a,j:=b,...].
  2285   - new function `upt' written [i..j(] which generates the list
  2286     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  2287     bound write [i..j], which is a shorthand for [i..j+1(].
  2288   - new lexicographic orderings and corresponding wellfoundedness theorems.
  2289 
  2290 * HOL/Arith:
  2291   - removed 'pred' (predecessor) function;
  2292   - generalized some theorems about n-1;
  2293   - many new laws about "div" and "mod";
  2294   - new laws about greatest common divisors (see theory ex/Primes);
  2295 
  2296 * HOL/Relation: renamed the relational operator r^-1 "converse"
  2297 instead of "inverse";
  2298 
  2299 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  2300   of the multiset ordering;
  2301 
  2302 * directory HOL/Real: a construction of the reals using Dedekind cuts
  2303   (not included by default);
  2304 
  2305 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  2306 
  2307 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  2308   programs, i.e. different program variables may have different types.
  2309 
  2310 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2311   [previously, this check worked only if the rewrite rule was unconditional]
  2312   Now rew can involve either definitions or equalities (either == or =).
  2313 
  2314 
  2315 *** ZF ***
  2316 
  2317 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  2318   only the theorems proved on ZF.ML;
  2319 
  2320 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2321   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2322   disjointness reasoning but breaking a few old proofs.
  2323 
  2324 * ZF/Update: new theory of function updates
  2325     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  2326   may also be iterated as in f(a:=b,c:=d,...);
  2327 
  2328 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  2329 
  2330 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2331   [previously, this check worked only if the rewrite rule was unconditional]
  2332   Now rew can involve either definitions or equalities (either == or =).
  2333 
  2334 * case_tac provided for compatibility with HOL
  2335     (like the old excluded_middle_tac, but with subgoals swapped)
  2336 
  2337 
  2338 *** Internal programming interfaces ***
  2339 
  2340 * Pure: several new basic modules made available for general use, see
  2341 also src/Pure/README;
  2342 
  2343 * improved the theory data mechanism to support encapsulation (data
  2344 kind name replaced by private Object.kind, acting as authorization
  2345 key); new type-safe user interface via functor TheoryDataFun; generic
  2346 print_data function becomes basically useless;
  2347 
  2348 * removed global_names compatibility flag -- all theory declarations
  2349 are qualified by default;
  2350 
  2351 * module Pure/Syntax now offers quote / antiquote translation
  2352 functions (useful for Hoare logic etc. with implicit dependencies);
  2353 see HOL/ex/Antiquote for an example use;
  2354 
  2355 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2356 cterm -> thm;
  2357 
  2358 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2359 subgoal;
  2360 
  2361 * Display.print_goals function moved to Locale.print_goals;
  2362 
  2363 * standard print function for goals supports current_goals_markers
  2364 variable for marking begin of proof, end of proof, start of goal; the
  2365 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2366 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2367 for example;
  2368 
  2369 
  2370 
  2371 New in Isabelle98 (January 1998)
  2372 --------------------------------
  2373 
  2374 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2375 
  2376 * changed lexical syntax of terms / types: dots made part of long
  2377 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2378 
  2379 * simpset (and claset) reference variable replaced by functions
  2380 simpset / simpset_ref;
  2381 
  2382 * no longer supports theory aliases (via merge) and non-trivial
  2383 implicit merge of thms' signatures;
  2384 
  2385 * most internal names of constants changed due to qualified names;
  2386 
  2387 * changed Pure/Sequence interface (see Pure/seq.ML);
  2388 
  2389 
  2390 *** General Changes ***
  2391 
  2392 * hierachically structured name spaces (for consts, types, axms, thms
  2393 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2394 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2395 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2396 long_names for fully qualified output names; NOTE: ML programs
  2397 (special tactics, packages etc.) referring to internal names may have
  2398 to be adapted to cope with fully qualified names; in case of severe
  2399 backward campatibility problems try setting 'global_names' at compile
  2400 time to have enrything declared within a flat name space; one may also
  2401 fine tune name declarations in theories via the 'global' and 'local'
  2402 section;
  2403 
  2404 * reimplemented the implicit simpset and claset using the new anytype
  2405 data filed in signatures; references simpset:simpset ref etc. are
  2406 replaced by functions simpset:unit->simpset and
  2407 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2408 to patch your ML files accordingly;
  2409 
  2410 * HTML output now includes theory graph data for display with Java
  2411 applet or isatool browser; data generated automatically via isatool
  2412 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2413 
  2414 * defs may now be conditional; improved rewrite_goals_tac to handle
  2415 conditional equations;
  2416 
  2417 * defs now admits additional type arguments, using TYPE('a) syntax;
  2418 
  2419 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2420 creates a new theory node; implicit merge of thms' signatures is
  2421 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2422 transfer:theory->thm->thm in (rare) cases;
  2423 
  2424 * improved handling of draft signatures / theories; draft thms (and
  2425 ctyps, cterms) are automatically promoted to real ones;
  2426 
  2427 * slightly changed interfaces for oracles: admit many per theory, named
  2428 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2429 
  2430 * print_goals: optional output of const types (set show_consts and
  2431 show_types);
  2432 
  2433 * improved output of warnings (###) and errors (***);
  2434 
  2435 * subgoal_tac displays a warning if the new subgoal has type variables;
  2436 
  2437 * removed old README and Makefiles;
  2438 
  2439 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2440 
  2441 * removed obsolete init_pps and init_database;
  2442 
  2443 * deleted the obsolete tactical STATE, which was declared by
  2444     fun STATE tacfun st = tacfun st st;
  2445 
  2446 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2447 (which abbreviates $HOME);
  2448 
  2449 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2450 use isatool fixseq to adapt your ML programs (this works for fully
  2451 qualified references to the Sequence structure only!);
  2452 
  2453 * use_thy no longer requires writable current directory; it always
  2454 reloads .ML *and* .thy file, if either one is out of date;
  2455 
  2456 
  2457 *** Classical Reasoner ***
  2458 
  2459 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2460 tactics that use classical reasoning to simplify a subgoal without
  2461 splitting it into several subgoals;
  2462 
  2463 * Safe_tac: like safe_tac but uses the default claset;
  2464 
  2465 
  2466 *** Simplifier ***
  2467 
  2468 * added simplification meta rules:
  2469     (asm_)(full_)simplify: simpset -> thm -> thm;
  2470 
  2471 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2472 logics (again);
  2473 
  2474 * added prems argument to simplification procedures;
  2475 
  2476 * HOL, FOL, ZF: added infix function `addsplits':
  2477   instead of `<simpset> setloop (split_tac <thms>)'
  2478   you can simply write `<simpset> addsplits <thms>'
  2479 
  2480 
  2481 *** Syntax ***
  2482 
  2483 * TYPE('a) syntax for type reflection terms;
  2484 
  2485 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2486 
  2487 * pretty printer: changed order of mixfix annotation preference (again!);
  2488 
  2489 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2490 
  2491 
  2492 *** HOL ***
  2493 
  2494 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2495   with `addloop' of the simplifier to faciliate case splitting in premises.
  2496 
  2497 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2498 
  2499 * HOL/Auth: new protocol proofs including some for the Internet
  2500   protocol TLS;
  2501 
  2502 * HOL/Map: new theory of `maps' a la VDM;
  2503 
  2504 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2505 cancelling out common nat summands from =, <, <= (in)equalities, or
  2506 differences; simplification procedures nat_cancel_factor for
  2507 cancelling common factor from =, <, <= (in)equalities over natural
  2508 sums; nat_cancel contains both kinds of procedures, it is installed by
  2509 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2510 
  2511 * HOL/simplifier: terms of the form
  2512   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2513   are rewritten to
  2514   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2515   and those of the form
  2516   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2517   are rewritten to
  2518   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2519 
  2520 * HOL/datatype
  2521   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2522 
  2523   P(t_case f1 ... fn x) =
  2524      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2525         ...
  2526        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2527      )
  2528 
  2529   and a theorem `split_t_case_asm' of the form
  2530 
  2531   P(t_case f1 ... fn x) =
  2532     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2533         ...
  2534        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2535      )
  2536   which can be added to a simpset via `addsplits'. The existing theorems
  2537   expand_list_case and expand_option_case have been renamed to
  2538   split_list_case and split_option_case.
  2539 
  2540 * HOL/Arithmetic:
  2541   - `pred n' is automatically converted to `n-1'.
  2542     Users are strongly encouraged not to use `pred' any longer,
  2543     because it will disappear altogether at some point.
  2544   - Users are strongly encouraged to write "0 < n" rather than
  2545     "n ~= 0". Theorems and proof tools have been modified towards this
  2546     `standard'.
  2547 
  2548 * HOL/Lists:
  2549   the function "set_of_list" has been renamed "set" (and its theorems too);
  2550   the function "nth" now takes its arguments in the reverse order and
  2551   has acquired the infix notation "!" as in "xs!n".
  2552 
  2553 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2554 
  2555 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2556   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2557 
  2558 * HOL/record: extensible records with schematic structural subtyping
  2559 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2560 still lacks various theorems and concrete record syntax;
  2561 
  2562 
  2563 *** HOLCF ***
  2564 
  2565 * removed "axioms" and "generated by" sections;
  2566 
  2567 * replaced "ops" section by extended "consts" section, which is capable of
  2568   handling the continuous function space "->" directly;
  2569 
  2570 * domain package:
  2571   . proves theorems immediately and stores them in the theory,
  2572   . creates hierachical name space,
  2573   . now uses normal mixfix annotations (instead of cinfix...),
  2574   . minor changes to some names and values (for consistency),
  2575   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2576   . separator between mutual domain defs: changed "," to "and",
  2577   . improved handling of sort constraints;  now they have to
  2578     appear on the left-hand side of the equations only;
  2579 
  2580 * fixed LAM <x,y,zs>.b syntax;
  2581 
  2582 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2583 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2584 
  2585 
  2586 *** FOL and ZF ***
  2587 
  2588 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2589   with `addloop' of the simplifier to faciliate case splitting in premises.
  2590 
  2591 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2592 in HOL, they strip ALL and --> from proved theorems;
  2593 
  2594 
  2595 
  2596 New in Isabelle94-8 (May 1997)
  2597 ------------------------------
  2598 
  2599 *** General Changes ***
  2600 
  2601 * new utilities to build / run / maintain Isabelle etc. (in parts
  2602 still somewhat experimental); old Makefiles etc. still functional;
  2603 
  2604 * new 'Isabelle System Manual';
  2605 
  2606 * INSTALL text, together with ./configure and ./build scripts;
  2607 
  2608 * reimplemented type inference for greater efficiency, better error
  2609 messages and clean internal interface;
  2610 
  2611 * prlim command for dealing with lots of subgoals (an easier way of
  2612 setting goals_limit);
  2613 
  2614 
  2615 *** Syntax ***
  2616 
  2617 * supports alternative (named) syntax tables (parser and pretty
  2618 printer); internal interface is provided by add_modesyntax(_i);
  2619 
  2620 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2621 be used in conjunction with the Isabelle symbol font; uses the
  2622 "symbols" syntax table;
  2623 
  2624 * added token_translation interface (may translate name tokens in
  2625 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2626 the current print_mode); IMPORTANT: user print translation functions
  2627 are responsible for marking newly introduced bounds
  2628 (Syntax.mark_boundT);
  2629 
  2630 * token translations for modes "xterm" and "xterm_color" that display
  2631 names in bold, underline etc. or colors (which requires a color
  2632 version of xterm);
  2633 
  2634 * infixes may now be declared with names independent of their syntax;
  2635 
  2636 * added typed_print_translation (like print_translation, but may
  2637 access type of constant);
  2638 
  2639 
  2640 *** Classical Reasoner ***
  2641 
  2642 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2643 some limitations.  Blast_tac...
  2644   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2645   + ignores elimination rules that don't have the correct format
  2646         (the conclusion MUST be a formula variable)
  2647   + ignores types, which can make HOL proofs fail
  2648   + rules must not require higher-order unification, e.g. apply_type in ZF
  2649     [message "Function Var's argument not a bound variable" relates to this]
  2650   + its proof strategy is more general but can actually be slower
  2651 
  2652 * substitution with equality assumptions no longer permutes other
  2653 assumptions;
  2654 
  2655 * minor changes in semantics of addafter (now called addaltern); renamed
  2656 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2657 (and access functions for it);
  2658 
  2659 * improved combination of classical reasoner and simplifier:
  2660   + functions for handling clasimpsets
  2661   + improvement of addss: now the simplifier is called _after_ the
  2662     safe steps.
  2663   + safe variant of addss called addSss: uses safe simplifications
  2664     _during_ the safe steps. It is more complete as it allows multiple
  2665     instantiations of unknowns (e.g. with slow_tac).
  2666 
  2667 *** Simplifier ***
  2668 
  2669 * added interface for simplification procedures (functions that
  2670 produce *proven* rewrite rules on the fly, depending on current
  2671 redex);
  2672 
  2673 * ordering on terms as parameter (used for ordered rewriting);
  2674 
  2675 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2676 
  2677 * the solver is now split into a safe and an unsafe part.
  2678 This should be invisible for the normal user, except that the
  2679 functions setsolver and addsolver have been renamed to setSolver and
  2680 addSolver; added safe_asm_full_simp_tac;
  2681 
  2682 
  2683 *** HOL ***
  2684 
  2685 * a generic induction tactic `induct_tac' which works for all datatypes and
  2686 also for type `nat';
  2687 
  2688 * a generic case distinction tactic `exhaust_tac' which works for all
  2689 datatypes and also for type `nat';
  2690 
  2691 * each datatype comes with a function `size';
  2692 
  2693 * patterns in case expressions allow tuple patterns as arguments to
  2694 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2695 
  2696 * primrec now also works with type nat;
  2697 
  2698 * recdef: a new declaration form, allows general recursive functions to be
  2699 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2700 
  2701 * the constant for negation has been renamed from "not" to "Not" to
  2702 harmonize with FOL, ZF, LK, etc.;
  2703 
  2704 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2705 infinite lists;
  2706 
  2707 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2708 
  2709 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2710 problems in commutative rings, using axiomatic type classes for + and *;
  2711 
  2712 * more examples in HOL/MiniML and HOL/Auth;
  2713 
  2714 * more default rewrite rules for quantifiers, union/intersection;
  2715 
  2716 * a new constant `arbitrary == @x.False';
  2717 
  2718 * HOLCF/IOA replaces old HOL/IOA;
  2719 
  2720 * HOLCF changes: derived all rules and arities
  2721   + axiomatic type classes instead of classes
  2722   + typedef instead of faking type definitions
  2723   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2724   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2725   + eliminated the types void, one, tr
  2726   + use unit lift and bool lift (with translations) instead of one and tr
  2727   + eliminated blift from Lift3.thy (use Def instead of blift)
  2728   all eliminated rules are derived as theorems --> no visible changes ;
  2729 
  2730 
  2731 *** ZF ***
  2732 
  2733 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2734 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2735 as ZF_cs addSIs [equalityI];
  2736 
  2737 
  2738 
  2739 New in Isabelle94-7 (November 96)
  2740 ---------------------------------
  2741 
  2742 * allowing negative levels (as offsets) in prlev and choplev;
  2743 
  2744 * super-linear speedup for large simplifications;
  2745 
  2746 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2747 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2748 FAIL); can suppress it using the command Delsimps (ex_simps @
  2749 all_simps); De Morgan laws are also now included, by default;
  2750 
  2751 * improved printing of ==>  :  ~:
  2752 
  2753 * new object-logic "Sequents" adds linear logic, while replacing LK
  2754 and Modal (thanks to Sara Kalvala);
  2755 
  2756 * HOL/Auth: correctness proofs for authentication protocols;
  2757 
  2758 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2759 examples on HOL/Auth);
  2760 
  2761 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2762 the rewriter and classical reasoner simultaneously;
  2763 
  2764 * function uresult no longer returns theorems in "standard" format;
  2765 regain previous version by: val uresult = standard o uresult;
  2766 
  2767 
  2768 
  2769 New in Isabelle94-6
  2770 -------------------
  2771 
  2772 * oracles -- these establish an interface between Isabelle and trusted
  2773 external reasoners, which may deliver results as theorems;
  2774 
  2775 * proof objects (in particular record all uses of oracles);
  2776 
  2777 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2778 
  2779 * "constdefs" section in theory files;
  2780 
  2781 * "primrec" section (HOL) no longer requires names;
  2782 
  2783 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2784 
  2785 
  2786 
  2787 New in Isabelle94-5
  2788 -------------------
  2789 
  2790 * reduced space requirements;
  2791 
  2792 * automatic HTML generation from theories;
  2793 
  2794 * theory files no longer require "..." (quotes) around most types;
  2795 
  2796 * new examples, including two proofs of the Church-Rosser theorem;
  2797 
  2798 * non-curried (1994) version of HOL is no longer distributed;
  2799 
  2800 
  2801 
  2802 New in Isabelle94-4
  2803 -------------------
  2804 
  2805 * greatly reduced space requirements;
  2806 
  2807 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2808 
  2809 * searchable theorem database (see the section "Retrieving theorems" on
  2810 page 8 of the Reference Manual);
  2811 
  2812 * new examples, including Grabczewski's monumental case study of the
  2813 Axiom of Choice;
  2814 
  2815 * The previous version of HOL renamed to Old_HOL;
  2816 
  2817 * The new version of HOL (previously called CHOL) uses a curried syntax
  2818 for functions.  Application looks like f a b instead of f(a,b);
  2819 
  2820 * Mutually recursive inductive definitions finally work in HOL;
  2821 
  2822 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2823 translates to the operator "split";
  2824 
  2825 
  2826 
  2827 New in Isabelle94-3
  2828 -------------------
  2829 
  2830 * new infix operator, addss, allowing the classical reasoner to
  2831 perform simplification at each step of its search.  Example:
  2832         fast_tac (cs addss ss)
  2833 
  2834 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2835 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2836 look like (a,b) instead of <a,b>;
  2837 
  2838 * PLEASE NOTE: CHOL will eventually replace HOL!
  2839 
  2840 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2841 It translates to the operator "split".  A new theory of integers is available;
  2842 
  2843 * In ZF, integer numerals now denote two's-complement binary integers.
  2844 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2845 
  2846 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2847 of the Axiom of Choice;
  2848 
  2849 
  2850 
  2851 New in Isabelle94-2
  2852 -------------------
  2853 
  2854 * Significantly faster resolution;
  2855 
  2856 * the different sections in a .thy file can now be mixed and repeated
  2857 freely;
  2858 
  2859 * Database of theorems for FOL, HOL and ZF.  New
  2860 commands including qed, qed_goal and bind_thm store theorems in the database.
  2861 
  2862 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2863 a given theory (thms_of), or find out what theory a theorem was proved in
  2864 (theory_of_thm);
  2865 
  2866 * Bugs fixed in the inductive definition and datatype packages;
  2867 
  2868 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2869 and HOL_dup_cs obsolete;
  2870 
  2871 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2872 have been removed;
  2873 
  2874 * Simpler definition of function space in ZF;
  2875 
  2876 * new results about cardinal and ordinal arithmetic in ZF;
  2877 
  2878 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2879 types;
  2880 
  2881 
  2882 $Id$