NEWS
author nipkow
Wed Feb 16 19:00:49 2005 +0100 (2005-02-16)
changeset 15534 fad04f5f822f
parent 15531 08c8dad8e399
child 15570 8d8c70b41bab
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 * The type Library.option is no more, along with the exception
    10   Library.OPTION: Isabelle now uses the standard option type.  The
    11   functions the, is_some, is_none, etc. are still in Library, but
    12   the constructors are now SOME and NONE instead of Some and None.
    13 
    14 * Document preparation: new antiquotations @{lhs thm} and @{rhs thm}
    15   printing the lhs/rhs of definitions, equations, inequations etc. 
    16 
    17 * isatool usedir: new option -f that allows specification of the ML
    18   file to be used by Isabelle; default is ROOT.ML.
    19 
    20 * Theory headers: the new header syntax for Isar theories is
    21 
    22   theory <name>
    23   imports <theory1> ... <theoryn>
    24   begin
    25 
    26   optionally also with a "files" section. The syntax
    27 
    28   theory <name> = <theory1> + ... + <theoryn>:
    29 
    30   will still be supported for some time but will eventually disappear.
    31   The syntax of old-style theories has not changed.
    32 
    33 * Theory loader: parent theories can now also be referred to via
    34   relative and absolute paths.
    35 
    36 * Provers/quasi.ML:  new transitivity reasoners for transitivity only
    37   and quasi orders.
    38 
    39 * Provers/trancl.ML:  new transitivity reasoner for transitive and
    40   reflexive-transitive closure of relations.
    41 
    42 * Provers/blast.ML:  new reference depth_limit to make blast's depth
    43   limit (previously hard-coded with a value of 20) user-definable.
    44 
    45 * Provers: new version of the subst method, for single-step rewriting: it now
    46   works in bound variable contexts. New is subst (asm), for rewriting an
    47   assumption. Thanks to Lucas Dixon! INCOMPATIBILITY: may rewrite a different
    48   subterm than the original subst method, which is still available under the
    49   name simplesubst.
    50 
    51 * Pure: thin_tac now works even if the assumption being deleted contains !! or ==>. 
    52   More generally, erule now works even if the major premise of the elimination rule
    53   contains !! or ==>.
    54 
    55 * Pure: considerably improved version of 'constdefs' command.  Now
    56   performs automatic type-inference of declared constants; additional
    57   support for local structure declarations (cf. locales and HOL
    58   records), see also isar-ref manual.  Potential INCOMPATIBILITY: need
    59   to observe strictly sequential dependencies of definitions within a
    60   single 'constdefs' section; moreover, the declared name needs to be
    61   an identifier.  If all fails, consider to fall back on 'consts' and
    62   'defs' separately.
    63 
    64 * Pure: improved indexed syntax and implicit structures.  First of
    65   all, indexed syntax provides a notational device for subscripted
    66   application, using the new syntax \<^bsub>term\<^esub> for arbitrary
    67   expressions.  Secondly, in a local context with structure
    68   declarations, number indexes \<^sub>n or the empty index (default
    69   number 1) refer to a certain fixed variable implicitly; option
    70   show_structs controls printing of implicit structures.  Typical
    71   applications of these concepts involve record types and locales.
    72 
    73 * Pure: clear separation of logical types and nonterminals, where the
    74   latter may only occur in 'syntax' specifications or type
    75   abbreviations.  Before that distinction was only partially
    76   implemented via type class "logic" vs. "{}".  Potential
    77   INCOMPATIBILITY in rare cases of improper use of 'types'/'consts'
    78   instead of 'nonterminals'/'syntax'.  Some very exotic syntax
    79   specifications may require further adaption (e.g. Cube/Base.thy).
    80 
    81 * Pure: removed obsolete type class "logic", use the top sort {}
    82   instead.  Note that non-logical types should be declared as
    83   'nonterminals' rather than 'types'.  INCOMPATIBILITY for new
    84   object-logic specifications.
    85 
    86 * Pure: print_tac now outputs the goal through the trace channel.
    87 
    88 * Pure: reference Namespace.unique_names included.  If true the
    89   (shortest) namespace-prefix is printed to disambiguate conflicts (as
    90   yet). If false the first entry wins (as during parsing). Default
    91   value is true.
    92 
    93 * Pure: tuned internal renaming of symbolic identifiers -- attach
    94   primes instead of base 26 numbers.
    95 
    96 * Pure: new flag show_var_qmarks to control printing of leading
    97   question marks of variable names.
    98 
    99 * Pure/Syntax: inner syntax includes (*(*nested*) comments*).
   100 
   101 * Pure/Syntax: pretty pinter now supports unbreakable blocks,
   102   specified in mixfix annotations as "(00...)".
   103 
   104 * Pure/Syntax: 'advanced' translation functions (parse_translation
   105   etc.) may depend on the signature of the theory context being
   106   presently used for parsing/printing, see also isar-ref manual.
   107 
   108 * Pure/Simplifier: simplification procedures may now take the current
   109   simpset into account (cf. Simplifier.simproc(_i) / mk_simproc
   110   interface), which is very useful for calling the Simplifier
   111   recursively.  Minor INCOMPATIBILITY: the 'prems' argument of
   112   simprocs is gone -- use prems_of_ss on the simpset instead.
   113   Moreover, the low-level mk_simproc no longer applies Logic.varify
   114   internally, to allow for use in a context of fixed variables.
   115 
   116 * Pure/Simplifier: Command "find_rewrites" takes a string and lists all
   117   equality theorems (not just those with attribute simp!) whose left-hand
   118   side matches the term given via the string. In PG the command can be
   119   activated via Isabelle -> Show me -> matching rewrites.
   120 
   121 * Provers: Simplifier and Classical Reasoner now support proof context
   122   dependent plug-ins (simprocs, solvers, wrappers etc.).  These extra
   123   components are stored in the theory and patched into the
   124   simpset/claset when used in an Isar proof context.  Context
   125   dependent components are maintained by the following theory
   126   operations:
   127 
   128     Simplifier.add_context_simprocs
   129     Simplifier.del_context_simprocs
   130     Simplifier.set_context_subgoaler
   131     Simplifier.reset_context_subgoaler
   132     Simplifier.add_context_looper
   133     Simplifier.del_context_looper
   134     Simplifier.add_context_unsafe_solver
   135     Simplifier.add_context_safe_solver
   136 
   137     Classical.add_context_safe_wrapper
   138     Classical.del_context_safe_wrapper
   139     Classical.add_context_unsafe_wrapper
   140     Classical.del_context_unsafe_wrapper
   141 
   142   IMPORTANT NOTE: proof tools (methods etc.) need to use
   143   local_simpset_of and local_claset_of to instead of the primitive
   144   Simplifier.get_local_simpset and Classical.get_local_claset,
   145   respectively, in order to see the context dependent fields!
   146 
   147 * Document preparation: antiquotations now provide the option
   148   'locale=NAME' to specify an alternative context used for evaluating
   149   and printing the subsequent argument, as in @{thm [locale=LC]
   150   fold_commute}, for example.
   151 
   152 * Document preparation: commands 'display_drafts' and 'print_drafts'
   153   perform simple output of raw sources.  Only those symbols that do
   154   not require additional LaTeX packages (depending on comments in
   155   isabellesym.sty) are displayed properly, everything else is left
   156   verbatim.  We use isatool display and isatool print as front ends;
   157   these are subject to the DVI_VIEWER and PRINT_COMMAND settings,
   158   respectively.
   159 
   160 * Document preparation: Proof scripts as well as some other commands
   161   such as ML or parse/print_translation can now be hidden in the document.
   162   Hiding is enabled by default, and can be disabled either via the option
   163   '-H false' of isatool usedir or by resetting the reference variable
   164   IsarOutput.hide_commands. Additional commands to be hidden may be
   165   declared using IsarOutput.add_hidden_commands.
   166 
   167 * ML: output via the Isabelle channels of writeln/warning/error
   168   etc. is now passed through Output.output, with a hook for arbitrary
   169   transformations depending on the print_mode (cf. Output.add_mode --
   170   the first active mode that provides a output function wins).
   171   Already formatted output may be embedded into further text via
   172   Output.raw; the result of Pretty.string_of/str_of and derived
   173   functions (string_of_term/cterm/thm etc.) is already marked raw to
   174   accommodate easy composition of diagnostic messages etc.
   175   Programmers rarely need to care about Output.output or Output.raw at
   176   all, with some notable exceptions: Output.output is required when
   177   bypassing the standard channels (writeln etc.), or in token
   178   translations to produce properly formatted results; Output.raw is
   179   required when capturing already output material that will eventually
   180   be presented to the user a second time.  For the default print mode,
   181   both Output.output and Output.raw have no effect.
   182 
   183 
   184 *** Isar ***
   185 
   186 * Debugging: new reference Toplevel.debug; default false.
   187   Set to make printing of exceptions THM, TERM, TYPE and THEORY more verbose.
   188   
   189 * Locales:
   190   - "includes" disallowed in declaration of named locales (command "locale").
   191   - Fixed parameter management in theorem generation for goals with "includes".
   192     INCOMPATIBILITY: rarely, the generated theorem statement is different.
   193 
   194 * New syntax
   195 
   196     <theorem_name> (<index>, ..., <index>-<index>, ...)
   197 
   198   for referring to specific theorems in a named list of theorems via
   199   indices.
   200 
   201 *** HOL ***
   202 
   203 * Datatype induction via method `induct' now preserves the name of the
   204   induction variable. For example, when proving P(xs::'a list) by induction
   205   on xs, the induction step is now P(xs) ==> P(a#xs) rather than
   206   P(list) ==> P(a#list) as previously.
   207 
   208 * HOL/record: reimplementation of records. Improved scalability for
   209   records with many fields, avoiding performance problems for type
   210   inference. Records are no longer composed of nested field types, but
   211   of nested extension types. Therefore the record type only grows
   212   linear in the number of extensions and not in the number of fields.
   213   The top-level (users) view on records is preserved.  Potential
   214   INCOMPATIBILITY only in strange cases, where the theory depends on
   215   the old record representation. The type generated for a record is
   216   called <record_name>_ext_type.
   217 
   218 * HOL/record: Reference record_quick_and_dirty_sensitive can be
   219   enabled to skip the proofs triggered by a record definition or a
   220   simproc (if quick_and_dirty is enabled). Definitions of large
   221   records can take quite long.
   222 
   223 * HOL/record: "record_upd_simproc" for simplification of multiple
   224   record updates enabled by default.  Moreover, trivial updates are
   225   also removed: r(|x := x r|) = r.  INCOMPATIBILITY: old proofs break
   226   occasionally, since simplification is more powerful by default.
   227 
   228 * HOL: symbolic syntax of Hilbert Choice Operator is now as follows:
   229 
   230   syntax (epsilon)
   231     "_Eps" :: "[pttrn, bool] => 'a"    ("(3\<some>_./ _)" [0, 10] 10)
   232 
   233   The symbol \<some> is displayed as the alternative epsilon of LaTeX
   234   and x-symbol; use option '-m epsilon' to get it actually printed.
   235   Moreover, the mathematically important symbolic identifier
   236   \<epsilon> becomes available as variable, constant etc.
   237 
   238 * HOL: "x > y" abbreviates "y < x" and "x >= y" abbreviates "y <= x".
   239   Similarly for all quantifiers: "ALL x > y" etc.
   240   The x-symbol for >= is \<ge>.
   241 
   242 * HOL/Set: "{x:A. P}" abbreviates "{x. x:A & P}"
   243            (and similarly for "\<in>" instead of ":")
   244 
   245 * HOL/SetInterval: The syntax for open intervals has changed:
   246 
   247   Old         New
   248   {..n(}   -> {..<n}
   249   {)n..}   -> {n<..}
   250   {m..n(}  -> {m..<n}
   251   {)m..n}  -> {m<..n}
   252   {)m..n(} -> {m<..<n}
   253 
   254   The old syntax is still supported but will disappear in the future.
   255   For conversion use the following emacs search and replace patterns:
   256 
   257   {)\([^\.]*\)\.\.  ->  {\1<\.\.}
   258   \.\.\([^(}]*\)(}  ->  \.\.<\1}
   259 
   260   They are not perfect but work quite well.
   261 
   262 * HOL: The syntax for 'setsum', summation over finite sets, has changed:
   263 
   264   The syntax for 'setsum (%x. e) A' used to be '\<Sum>x:A. e'
   265   and is now either 'SUM x:A. e' or '\<Sum>x\<in>A. e'.
   266 
   267   There is new syntax for summation over finite sets:
   268 
   269   '\<Sum>x | P. e'    is the same as  'setsum (%x. e) {x. P}'
   270   '\<Sum>x=a..b. e'   is the same as  'setsum (%x. e) {a..b}'
   271   '\<Sum>x=a..<b. e'  is the same as  'setsum (%x. e) {a..<b}'
   272   '\<Sum>x<k. e'      is the same as  'setsum (%x. e) {..<k}'
   273 
   274   Function 'Summation' over nat is gone, its syntax '\<Sum>i<k. e'
   275   now translates into 'setsum' as above.
   276 
   277 * HOL: Finite set induction: In Isar proofs, the insert case is now
   278   "case (insert x F)" instead of the old counterintuitive "case (insert F x)".
   279 
   280 * HOL/Simplifier:
   281 
   282   - Is now set up to reason about transitivity chains involving "trancl"
   283   (r^+) and "rtrancl" (r^*) by setting up tactics provided by
   284   Provers/trancl.ML as additional solvers.  INCOMPATIBILITY: old proofs break
   285   occasionally as simplification may now solve more goals than previously.
   286 
   287   - Converts x <= y into x = y if assumption y <= x is present.  Works for
   288   all partial orders (class "order"), in particular numbers and sets. For
   289   linear orders (e.g. numbers) it treats ~ x < y just like y <= x.
   290 
   291   - Simproc for "let x = a in f x"
   292   If a is a free or bound variable or a constant then the let is unfolded.
   293   Otherwise first a is simplified to a', and then f a' is simplified to
   294   g. If possible we abstract a' from g arriving at "let x = a' in g' x",
   295   otherwise we unfold the let and arrive at g. The simproc can be 
   296   enabled/disabled by the reference use_let_simproc. Potential
   297   INCOMPATIBILITY since simplification is more powerful by default.
   298  
   299 * HOL: new 'isatool dimacs2hol' to convert files in DIMACS CNF format
   300   (containing Boolean satisfiability problems) into Isabelle/HOL theories.
   301 
   302 
   303 *** HOLCF ***
   304 
   305 * HOLCF: discontinued special version of 'constdefs' (which used to
   306   support continuous functions) in favor of the general Pure one with
   307   full type-inference.
   308 
   309 
   310 *** ZF ***
   311 
   312 * ZF/ex/{Group,Ring}: examples in abstract algebra, including the
   313   First Isomorphism Theorem (on quotienting by the kernel of a
   314   homomorphism).
   315 
   316 * ZF/Simplifier: install second copy of type solver that actually
   317   makes use of TC rules declared to Isar proof contexts (or locales);
   318   the old version is still required for ML proof scripts.
   319 
   320 
   321 
   322 New in Isabelle2004 (April 2004)
   323 --------------------------------
   324 
   325 *** General ***
   326 
   327 * Provers/order.ML:  new efficient reasoner for partial and linear orders.
   328   Replaces linorder.ML.
   329 
   330 * Pure: Greek letters (except small lambda, \<lambda>), as well as Gothic
   331   (\<aa>...\<zz>\<AA>...\<ZZ>), calligraphic (\<A>...\<Z>), and Euler
   332   (\<a>...\<z>), are now considered normal letters, and can therefore
   333   be used anywhere where an ASCII letter (a...zA...Z) has until
   334   now. COMPATIBILITY: This obviously changes the parsing of some
   335   terms, especially where a symbol has been used as a binder, say
   336   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed
   337   as an identifier.  Fix it by inserting a space around former
   338   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in
   339   existing theory and ML files.
   340 
   341 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.
   342 
   343 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now
   344   allowed in identifiers. Similar to Greek letters \<^isub> is now considered
   345   a normal (but invisible) letter. For multiple letter subscripts repeat
   346   \<^isub> like this: x\<^isub>1\<^isub>2.
   347 
   348 * Pure: There are now sub-/superscripts that can span more than one
   349   character. Text between \<^bsub> and \<^esub> is set in subscript in
   350   ProofGeneral and LaTeX, text between \<^bsup> and \<^esup> in
   351   superscript. The new control characters are not identifier parts.
   352 
   353 * Pure: Control-symbols of the form \<^raw:...> will literally print the
   354   content of "..." to the latex file instead of \isacntrl... . The "..."
   355   may consist of any printable characters excluding the end bracket >.
   356 
   357 * Pure: Using new Isar command "finalconsts" (or the ML functions
   358   Theory.add_finals or Theory.add_finals_i) it is now possible to
   359   declare constants "final", which prevents their being given a definition
   360   later.  It is useful for constants whose behaviour is fixed axiomatically
   361   rather than definitionally, such as the meta-logic connectives.
   362 
   363 * Pure: 'instance' now handles general arities with general sorts
   364   (i.e. intersections of classes),
   365 
   366 * Presentation: generated HTML now uses a CSS style sheet to make layout
   367   (somewhat) independent of content. It is copied from lib/html/isabelle.css.
   368   It can be changed to alter the colors/layout of generated pages.
   369 
   370 
   371 *** Isar ***
   372 
   373 * Tactic emulation methods rule_tac, erule_tac, drule_tac, frule_tac,
   374   cut_tac, subgoal_tac and thin_tac:
   375   - Now understand static (Isar) contexts.  As a consequence, users of Isar
   376     locales are no longer forced to write Isar proof scripts.
   377     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
   378     emulations.
   379   - INCOMPATIBILITY: names of variables to be instantiated may no
   380     longer be enclosed in quotes.  Instead, precede variable name with `?'.
   381     This is consistent with the instantiation attribute "where".
   382 
   383 * Attributes "where" and "of":
   384   - Now take type variables of instantiated theorem into account when reading
   385     the instantiation string.  This fixes a bug that caused instantiated
   386     theorems to have too special types in some circumstances.
   387   - "where" permits explicit instantiations of type variables.
   388 
   389 * Calculation commands "moreover" and "also" no longer interfere with
   390   current facts ("this"), admitting arbitrary combinations with "then"
   391   and derived forms.
   392 
   393 * Locales:
   394   - Goal statements involving the context element "includes" no longer
   395     generate theorems with internal delta predicates (those ending on
   396     "_axioms") in the premise.
   397     Resolve particular premise with <locale>.intro to obtain old form.
   398   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
   399     specification and "includes" elements in goal statement.
   400   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
   401     [intro?] and [elim?] (respectively) by default.
   402   - Experimental command for instantiation of locales in proof contexts:
   403         instantiate <label>[<attrs>]: <loc>
   404     Instantiates locale <loc> and adds all its theorems to the current context
   405     taking into account their attributes.  Label and attrs are optional
   406     modifiers, like in theorem declarations.  If present, names of
   407     instantiated theorems are qualified with <label>, and the attributes
   408     <attrs> are applied after any attributes these theorems might have already.
   409       If the locale has assumptions, a chained fact of the form
   410     "<loc> t1 ... tn" is expected from which instantiations of the parameters
   411     are derived.  The command does not support old-style locales declared
   412     with "locale (open)".
   413       A few (very simple) examples can be found in FOL/ex/LocaleInst.thy.
   414 
   415 * HOL: Tactic emulation methods induct_tac and case_tac understand static
   416   (Isar) contexts.
   417 
   418 
   419 *** HOL ***
   420 
   421 * Proof import: new image HOL4 contains the imported library from
   422   the HOL4 system with about 2500 theorems. It is imported by
   423   replaying proof terms produced by HOL4 in Isabelle. The HOL4 image
   424   can be used like any other Isabelle image.  See
   425   HOL/Import/HOL/README for more information.
   426 
   427 * Simplifier:
   428   - Much improved handling of linear and partial orders.
   429     Reasoners for linear and partial orders are set up for type classes
   430     "linorder" and "order" respectively, and are added to the default simpset
   431     as solvers.  This means that the simplifier can build transitivity chains
   432     to solve goals from the assumptions.
   433   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications
   434     of blast or auto after simplification become unnecessary because the goal
   435     is solved by simplification already.
   436 
   437 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws,
   438     all proved in axiomatic type classes for semirings, rings and fields.
   439 
   440 * Numerics:
   441   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are
   442     now formalized using the Ring_and_Field theory mentioned above.
   443   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently
   444     than before, because now they are set up once in a generic manner.
   445   - INCOMPATIBILITY: many type-specific arithmetic laws have gone.
   446     Look for the general versions in Ring_and_Field (and Power if they concern
   447     exponentiation).
   448 
   449 * Type "rat" of the rational numbers is now available in HOL-Complex.
   450 
   451 * Records:
   452   - Record types are now by default printed with their type abbreviation
   453     instead of the list of all field types. This can be configured via
   454     the reference "print_record_type_abbr".
   455   - Simproc "record_upd_simproc" for simplification of multiple updates added
   456     (not enabled by default).
   457   - Simproc "record_ex_sel_eq_simproc" to simplify EX x. sel r = x resp.
   458     EX x. x = sel r to True (not enabled by default).
   459   - Tactic "record_split_simp_tac" to split and simplify records added.
   460 
   461 * 'specification' command added, allowing for definition by
   462   specification.  There is also an 'ax_specification' command that
   463   introduces the new constants axiomatically.
   464 
   465 * arith(_tac) is now able to generate counterexamples for reals as well.
   466 
   467 * HOL-Algebra: new locale "ring" for non-commutative rings.
   468 
   469 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
   470   definitions, thanks to Sava Krsti\'{c} and John Matthews.
   471 
   472 * HOL-Matrix: a first theory for matrices in HOL with an application of
   473   matrix theory to linear programming.
   474 
   475 * Unions and Intersections:
   476   The latex output syntax of UN and INT has been changed
   477   from "\Union x \in A. B" to "\Union_{x \in A} B"
   478   i.e. the index formulae has become a subscript.
   479   Similarly for "\Union x. B", and for \Inter instead of \Union.
   480 
   481 * Unions and Intersections over Intervals:
   482   There is new short syntax "UN i<=n. A" for "UN i:{0..n}. A". There is
   483   also an x-symbol version with subscripts "\<Union>\<^bsub>i <= n\<^esub>. A"
   484   like in normal math, and corresponding versions for < and for intersection.
   485 
   486 * ML: the legacy theory structures Int and List have been removed. They had
   487   conflicted with ML Basis Library structures having the same names.
   488 
   489 * 'refute' command added to search for (finite) countermodels.  Only works
   490   for a fragment of HOL.  The installation of an external SAT solver is
   491   highly recommended.  See "HOL/Refute.thy" for details.
   492 
   493 * 'quickcheck' command: Allows to find counterexamples by evaluating
   494   formulae under an assignment of free variables to random values.
   495   In contrast to 'refute', it can deal with inductive datatypes,
   496   but cannot handle quantifiers. See "HOL/ex/Quickcheck_Examples.thy"
   497   for examples.
   498 
   499 
   500 *** HOLCF ***
   501 
   502 * Streams now come with concatenation and are part of the HOLCF image
   503 
   504 
   505 
   506 New in Isabelle2003 (May 2003)
   507 ------------------------------
   508 
   509 *** General ***
   510 
   511 * Provers/simplifier:
   512 
   513   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   514     Assumptions are now subject to complete mutual simplification,
   515     not just from left to right. The simplifier now preserves
   516     the order of assumptions.
   517 
   518     Potential INCOMPATIBILITY:
   519 
   520     -- simp sometimes diverges where the old version did
   521        not, e.g. invoking simp on the goal
   522 
   523         [| P (f x); y = x; f x = f y |] ==> Q
   524 
   525        now gives rise to the infinite reduction sequence
   526 
   527         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   528 
   529        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   530        kind of problem.
   531 
   532     -- Tactics combining classical reasoner and simplification (such as auto)
   533        are also affected by this change, because many of them rely on
   534        simp. They may sometimes diverge as well or yield a different numbers
   535        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   536        in case of problems. Sometimes subsequent calls to the classical
   537        reasoner will fail because a preceeding call to the simplifier too
   538        eagerly simplified the goal, e.g. deleted redundant premises.
   539 
   540   - The simplifier trace now shows the names of the applied rewrite rules
   541 
   542   - You can limit the number of recursive invocations of the simplifier
   543     during conditional rewriting (where the simplifie tries to solve the
   544     conditions before applying the rewrite rule):
   545     ML "simp_depth_limit := n"
   546     where n is an integer. Thus you can force termination where previously
   547     the simplifier would diverge.
   548 
   549   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   550 
   551   - No longer aborts on failed congruence proof.  Instead, the
   552     congruence is ignored.
   553 
   554 * Pure: New generic framework for extracting programs from constructive
   555   proofs. See HOL/Extraction.thy for an example instantiation, as well
   556   as HOL/Extraction for some case studies.
   557 
   558 * Pure: The main goal of the proof state is no longer shown by default, only
   559 the subgoals. This behaviour is controlled by a new flag.
   560    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   561 (ML: Proof.show_main_goal).
   562 
   563 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   564 rules whose conclusion matches subgoal 1:
   565       PG menu: Isabelle/Isar -> Show me -> matching rules
   566 The rules are ordered by how closely they match the subgoal.
   567 In particular, rules that solve a subgoal outright are displayed first
   568 (or rather last, the way they are printed).
   569 (ML: ProofGeneral.print_intros())
   570 
   571 * Pure: New flag trace_unify_fail causes unification to print
   572 diagnostic information (PG: in trace buffer) when it fails. This is
   573 useful for figuring out why single step proofs like rule, erule or
   574 assumption failed.
   575 
   576 * Pure: Locale specifications now produce predicate definitions
   577 according to the body of text (covering assumptions modulo local
   578 definitions); predicate "loc_axioms" covers newly introduced text,
   579 while "loc" is cumulative wrt. all included locale expressions; the
   580 latter view is presented only on export into the global theory
   581 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   582 on the old view without predicates;
   583 
   584 * Pure: predefined locales "var" and "struct" are useful for sharing
   585 parameters (as in CASL, for example); just specify something like
   586 ``var x + var y + struct M'' as import;
   587 
   588 * Pure: improved thms_containing: proper indexing of facts instead of
   589 raw theorems; check validity of results wrt. current name space;
   590 include local facts of proof configuration (also covers active
   591 locales), cover fixed variables in index; may use "_" in term
   592 specification; an optional limit for the number of printed facts may
   593 be given (the default is 40);
   594 
   595 * Pure: disallow duplicate fact bindings within new-style theory files
   596 (batch-mode only);
   597 
   598 * Provers: improved induct method: assumptions introduced by case
   599 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   600 the goal statement); "foo" still refers to all facts collectively;
   601 
   602 * Provers: the function blast.overloaded has been removed: all constants
   603 are regarded as potentially overloaded, which improves robustness in exchange
   604 for slight decrease in efficiency;
   605 
   606 * Provers/linorder: New generic prover for transitivity reasoning over
   607 linear orders.  Note: this prover is not efficient!
   608 
   609 * Isar: preview of problems to finish 'show' now produce an error
   610 rather than just a warning (in interactive mode);
   611 
   612 
   613 *** HOL ***
   614 
   615 * arith(_tac)
   616 
   617  - Produces a counter example if it cannot prove a goal.
   618    Note that the counter example may be spurious if the goal is not a formula
   619    of quantifier-free linear arithmetic.
   620    In ProofGeneral the counter example appears in the trace buffer.
   621 
   622  - Knows about div k and mod k where k is a numeral of type nat or int.
   623 
   624  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   625    linear arithmetic fails. This takes account of quantifiers and divisibility.
   626    Presburger arithmetic can also be called explicitly via presburger(_tac).
   627 
   628 * simp's arithmetic capabilities have been enhanced a bit: it now
   629 takes ~= in premises into account (by performing a case split);
   630 
   631 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   632 are distributed over a sum of terms;
   633 
   634 * New tactic "trans_tac" and method "trans" instantiate
   635 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   636 "<=", "<" and "=").
   637 
   638 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main
   639 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   640 
   641 * 'typedef' command has new option "open" to suppress the set
   642 definition;
   643 
   644 * functions Min and Max on finite sets have been introduced (theory
   645 Finite_Set);
   646 
   647 * attribute [symmetric] now works for relations as well; it turns
   648 (x,y) : R^-1 into (y,x) : R, and vice versa;
   649 
   650 * induct over a !!-quantified statement (say !!x1..xn):
   651   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   652 
   653 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   654 %x. None. Warning: empty_def now refers to the previously hidden definition
   655 of the empty set.
   656 
   657 * Algebra: formalization of classical algebra.  Intended as base for
   658 any algebraic development in Isabelle.  Currently covers group theory
   659 (up to Sylow's theorem) and ring theory (Universal Property of
   660 Univariate Polynomials).  Contributions welcome;
   661 
   662 * GroupTheory: deleted, since its material has been moved to Algebra;
   663 
   664 * Complex: new directory of the complex numbers with numeric constants,
   665 nonstandard complex numbers, and some complex analysis, standard and
   666 nonstandard (Jacques Fleuriot);
   667 
   668 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   669 
   670 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques
   671 Fleuriot);
   672 
   673 * Real/HahnBanach: updated and adapted to locales;
   674 
   675 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   676 Gray and Kramer);
   677 
   678 * UNITY: added the Meier-Sanders theory of progress sets;
   679 
   680 * MicroJava: bytecode verifier and lightweight bytecode verifier
   681 as abstract algorithms, instantiated to the JVM;
   682 
   683 * Bali: Java source language formalization. Type system, operational
   684 semantics, axiomatic semantics. Supported language features:
   685 classes, interfaces, objects,virtual methods, static methods,
   686 static/instance fields, arrays, access modifiers, definite
   687 assignment, exceptions.
   688 
   689 
   690 *** ZF ***
   691 
   692 * ZF/Constructible: consistency proof for AC (Gdel's constructible
   693 universe, etc.);
   694 
   695 * Main ZF: virtually all theories converted to new-style format;
   696 
   697 
   698 *** ML ***
   699 
   700 * Pure: Tactic.prove provides sane interface for internal proofs;
   701 omits the infamous "standard" operation, so this is more appropriate
   702 than prove_goalw_cterm in many situations (e.g. in simprocs);
   703 
   704 * Pure: improved error reporting of simprocs;
   705 
   706 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   707 up simprocs;
   708 
   709 
   710 *** Document preparation ***
   711 
   712 * uses \par instead of \\ for line breaks in theory text. This may
   713 shift some page breaks in large documents. To get the old behaviour
   714 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   715 
   716 * minimized dependencies of isabelle.sty and isabellesym.sty on
   717 other packages
   718 
   719 * \<euro> now needs package babel/greek instead of marvosym (which
   720 broke \Rightarrow)
   721 
   722 * normal size for \<zero>...\<nine> (uses \mathbf instead of
   723 textcomp package)
   724 
   725 
   726 
   727 New in Isabelle2002 (March 2002)
   728 --------------------------------
   729 
   730 *** Document preparation ***
   731 
   732 * greatly simplified document preparation setup, including more
   733 graceful interpretation of isatool usedir -i/-d/-D options, and more
   734 instructive isatool mkdir; users should basically be able to get
   735 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   736 users may run a separate document processing stage manually like this:
   737 "isatool usedir -D output HOL Test && isatool document Test/output";
   738 
   739 * theory dependency graph may now be incorporated into documents;
   740 isatool usedir -g true will produce session_graph.eps/.pdf for use
   741 with \includegraphics of LaTeX;
   742 
   743 * proper spacing of consecutive markup elements, especially text
   744 blocks after section headings;
   745 
   746 * support bold style (for single symbols only), input syntax is like
   747 this: "\<^bold>\<alpha>" or "\<^bold>A";
   748 
   749 * \<bullet> is now output as bold \cdot by default, which looks much
   750 better in printed text;
   751 
   752 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   753 note that these symbols are currently unavailable in Proof General /
   754 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   755 
   756 * isatool latex no longer depends on changed TEXINPUTS, instead
   757 isatool document copies the Isabelle style files to the target
   758 location;
   759 
   760 
   761 *** Isar ***
   762 
   763 * Pure/Provers: improved proof by cases and induction;
   764   - 'case' command admits impromptu naming of parameters (such as
   765     "case (Suc n)");
   766   - 'induct' method divinates rule instantiation from the inductive
   767     claim; no longer requires excessive ?P bindings for proper
   768     instantiation of cases;
   769   - 'induct' method properly enumerates all possibilities of set/type
   770     rules; as a consequence facts may be also passed through *type*
   771     rules without further ado;
   772   - 'induct' method now derives symbolic cases from the *rulified*
   773     rule (before it used to rulify cases stemming from the internal
   774     atomized version); this means that the context of a non-atomic
   775     statement becomes is included in the hypothesis, avoiding the
   776     slightly cumbersome show "PROP ?case" form;
   777   - 'induct' may now use elim-style induction rules without chaining
   778     facts, using ``missing'' premises from the goal state; this allows
   779     rules stemming from inductive sets to be applied in unstructured
   780     scripts, while still benefitting from proper handling of non-atomic
   781     statements; NB: major inductive premises need to be put first, all
   782     the rest of the goal is passed through the induction;
   783   - 'induct' proper support for mutual induction involving non-atomic
   784     rule statements (uses the new concept of simultaneous goals, see
   785     below);
   786   - append all possible rule selections, but only use the first
   787     success (no backtracking);
   788   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   789   - undeclared rule case names default to numbers 1, 2, 3, ...;
   790   - added 'print_induct_rules' (covered by help item in recent Proof
   791     General versions);
   792   - moved induct/cases attributes to Pure, methods to Provers;
   793   - generic method setup instantiated for FOL and HOL;
   794 
   795 * Pure: support multiple simultaneous goal statements, for example
   796 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   797 meta-level mechanism, this acts as if several individual goals had
   798 been stated separately; in particular common proof methods need to be
   799 repeated in order to cover all claims; note that a single elimination
   800 step is *not* sufficient to establish the two conjunctions, so this
   801 fails:
   802 
   803   assume "A & B" then have A and B ..   (*".." fails*)
   804 
   805 better use "obtain" in situations as above; alternative refer to
   806 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   807 
   808 * Pure: proper integration with ``locales''; unlike the original
   809 version by Florian Kammller, Isar locales package high-level proof
   810 contexts rather than raw logical ones (e.g. we admit to include
   811 attributes everywhere); operations on locales include merge and
   812 rename; support for implicit arguments (``structures''); simultaneous
   813 type-inference over imports and text; see also HOL/ex/Locales.thy for
   814 some examples;
   815 
   816 * Pure: the following commands have been ``localized'', supporting a
   817 target locale specification "(in name)": 'lemma', 'theorem',
   818 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   819 stored both within the locale and at the theory level (exported and
   820 qualified by the locale name);
   821 
   822 * Pure: theory goals may now be specified in ``long'' form, with
   823 ad-hoc contexts consisting of arbitrary locale elements. for example
   824 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   825 definitions may be given, too); the result is a meta-level rule with
   826 the context elements being discharged in the obvious way;
   827 
   828 * Pure: new proof command 'using' allows to augment currently used
   829 facts after a goal statement ('using' is syntactically analogous to
   830 'apply', but acts on the goal's facts only); this allows chained facts
   831 to be separated into parts given before and after a claim, as in
   832 ``from a and b have C using d and e <proof>'';
   833 
   834 * Pure: renamed "antecedent" case to "rule_context";
   835 
   836 * Pure: new 'judgment' command records explicit information about the
   837 object-logic embedding (used by several tools internally); no longer
   838 use hard-wired "Trueprop";
   839 
   840 * Pure: added 'corollary' command;
   841 
   842 * Pure: fixed 'token_translation' command;
   843 
   844 * Pure: removed obsolete 'exported' attribute;
   845 
   846 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   847 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   848 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   849 
   850 * Pure: method 'atomize' presents local goal premises as object-level
   851 statements (atomic meta-level propositions); setup controlled via
   852 rewrite rules declarations of 'atomize' attribute; example
   853 application: 'induct' method with proper rule statements in improper
   854 proof *scripts*;
   855 
   856 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   857 now consider the syntactic context of assumptions, giving a better
   858 chance to get type-inference of the arguments right (this is
   859 especially important for locales);
   860 
   861 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   862 mode;
   863 
   864 * Pure/obtain: the formal conclusion "thesis", being marked as
   865 ``internal'', may no longer be reference directly in the text;
   866 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   867 situations;
   868 
   869 * Pure: generic 'sym' attribute which declares a rule both as pure
   870 'elim?' and for the 'symmetric' operation;
   871 
   872 * Pure: marginal comments ``--'' may now occur just anywhere in the
   873 text; the fixed correlation with particular command syntax has been
   874 discontinued;
   875 
   876 * Pure: new method 'rules' is particularly well-suited for proof
   877 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   878 but often produces more compact proof terms with less detours;
   879 
   880 * Pure/Provers/classical: simplified integration with pure rule
   881 attributes and methods; the classical "intro?/elim?/dest?"
   882 declarations coincide with the pure ones; the "rule" method no longer
   883 includes classically swapped intros; "intro" and "elim" methods no
   884 longer pick rules from the context; also got rid of ML declarations
   885 AddXIs/AddXEs/AddXDs; all of this has some potential for
   886 INCOMPATIBILITY;
   887 
   888 * Provers/classical: attribute 'swapped' produces classical inversions
   889 of introduction rules;
   890 
   891 * Provers/simplifier: 'simplified' attribute may refer to explicit
   892 rules instead of full simplifier context; 'iff' attribute handles
   893 conditional rules;
   894 
   895 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   896 
   897 * HOL: 'recdef' now fails on unfinished automated proofs, use
   898 "(permissive)" option to recover old behavior;
   899 
   900 * HOL: 'inductive' no longer features separate (collective) attributes
   901 for 'intros' (was found too confusing);
   902 
   903 * HOL: properly declared induction rules less_induct and
   904 wf_induct_rule;
   905 
   906 
   907 *** HOL ***
   908 
   909 * HOL: moved over to sane numeral syntax; the new policy is as
   910 follows:
   911 
   912   - 0 and 1 are polymorphic constants, which are defined on any
   913   numeric type (nat, int, real etc.);
   914 
   915   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   916   binary representation internally;
   917 
   918   - type nat has special constructor Suc, and generally prefers Suc 0
   919   over 1::nat and Suc (Suc 0) over 2::nat;
   920 
   921 This change may cause significant problems of INCOMPATIBILITY; here
   922 are some hints on converting existing sources:
   923 
   924   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   925   entities, so expressions involving "-" (unary or binary minus) need
   926   to be spaced properly;
   927 
   928   - existing occurrences of "1" may need to be constraint "1::nat" or
   929   even replaced by Suc 0; similar for old "2";
   930 
   931   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   932 
   933   - remove all special provisions on numerals in proofs;
   934 
   935 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   936 representation (depends on bin_arith_simps in the default context);
   937 
   938 * HOL: symbolic syntax for x^2 (numeral 2);
   939 
   940 * HOL: the class of all HOL types is now called "type" rather than
   941 "term"; INCOMPATIBILITY, need to adapt references to this type class
   942 in axclass/classes, instance/arities, and (usually rare) occurrences
   943 in typings (of consts etc.); internally the class is called
   944 "HOL.type", ML programs should refer to HOLogic.typeS;
   945 
   946 * HOL/record package improvements:
   947   - new derived operations "fields" to build a partial record section,
   948     "extend" to promote a fixed record to a record scheme, and
   949     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   950     declared as simp by default;
   951   - shared operations ("more", "fields", etc.) now need to be always
   952     qualified) --- potential INCOMPATIBILITY;
   953   - removed "make_scheme" operations (use "make" with "extend") --
   954     INCOMPATIBILITY;
   955   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   956   - provides cases/induct rules for use with corresponding Isar
   957     methods (for concrete records, record schemes, concrete more
   958     parts, and schematic more parts -- in that order);
   959   - internal definitions directly based on a light-weight abstract
   960     theory of product types over typedef rather than datatype;
   961 
   962 * HOL: generic code generator for generating executable ML code from
   963 specifications; specific support for HOL constructs such as inductive
   964 datatypes and sets, as well as recursive functions; can be invoked
   965 via 'generate_code' theory section;
   966 
   967 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   968 
   969 * HOL: consolidated and renamed several theories.  In particular:
   970         Ord.thy has been absorbed into HOL.thy
   971         String.thy has been absorbed into List.thy
   972 
   973 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   974 (beware of argument permutation!);
   975 
   976 * HOL: linorder_less_split superseded by linorder_cases;
   977 
   978 * HOL/List: "nodups" renamed to "distinct";
   979 
   980 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   981 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   982   - Ex_def has changed, now need to use some_eq_ex
   983 
   984 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   985 in this (rare) case use:
   986 
   987   delSWrapper "split_all_tac"
   988   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   989 
   990 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   991 MAY FAIL;
   992 
   993 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   994 Isabelle's type classes, ^ on functions and relations has too general
   995 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   996 necessary to attach explicit type constraints;
   997 
   998 * HOL/Relation: the prefix name of the infix "O" has been changed from
   999 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
  1000 renamed accordingly (eg "compI" -> "rel_compI").
  1001 
  1002 * HOL: syntax translations now work properly with numerals and records
  1003 expressions;
  1004 
  1005 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
  1006 of "lam" -- INCOMPATIBILITY;
  1007 
  1008 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
  1009 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
  1010 renamed "Product_Type.unit";
  1011 
  1012 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
  1013 
  1014 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
  1015 the "cases" method);
  1016 
  1017 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
  1018 Florian Kammller);
  1019 
  1020 * HOL/IMP: updated and converted to new-style theory format; several
  1021 parts turned into readable document, with proper Isar proof texts and
  1022 some explanations (by Gerwin Klein);
  1023 
  1024 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
  1025 
  1026 * HOL-Hyperreal is now a logic image;
  1027 
  1028 
  1029 *** HOLCF ***
  1030 
  1031 * Isar: consts/constdefs supports mixfix syntax for continuous
  1032 operations;
  1033 
  1034 * Isar: domain package adapted to new-style theory format, e.g. see
  1035 HOLCF/ex/Dnat.thy;
  1036 
  1037 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
  1038 potential INCOMPATIBILITY; now use plain induct_tac instead of former
  1039 lift.induct_tac, always use UU instead of Undef;
  1040 
  1041 * HOLCF/IMP: updated and converted to new-style theory;
  1042 
  1043 
  1044 *** ZF ***
  1045 
  1046 * Isar: proper integration of logic-specific tools and packages,
  1047 including theory commands '(co)inductive', '(co)datatype',
  1048 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
  1049 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
  1050 
  1051 * theory Main no longer includes AC; for the Axiom of Choice, base
  1052 your theory on Main_ZFC;
  1053 
  1054 * the integer library now covers quotients and remainders, with many
  1055 laws relating division to addition, multiplication, etc.;
  1056 
  1057 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
  1058 typeless version of the formalism;
  1059 
  1060 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
  1061 format;
  1062 
  1063 * ZF/Induct: new directory for examples of inductive definitions,
  1064 including theory Multiset for multiset orderings; converted to
  1065 new-style theory format;
  1066 
  1067 * ZF: many new theorems about lists, ordinals, etc.;
  1068 
  1069 
  1070 *** General ***
  1071 
  1072 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
  1073 variable proof controls level of detail: 0 = no proofs (only oracle
  1074 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
  1075 also ref manual for further ML interfaces;
  1076 
  1077 * Pure/axclass: removed obsolete ML interface
  1078 goal_subclass/goal_arity;
  1079 
  1080 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
  1081 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
  1082 separate tokens, so expressions involving minus need to be spaced
  1083 properly;
  1084 
  1085 * Pure/syntax: support non-oriented infixes, using keyword "infix"
  1086 rather than "infixl" or "infixr";
  1087 
  1088 * Pure/syntax: concrete syntax for dummy type variables admits genuine
  1089 sort constraint specifications in type inference; e.g. "x::_::foo"
  1090 ensures that the type of "x" is of sort "foo" (but not necessarily a
  1091 type variable);
  1092 
  1093 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
  1094 control output of nested => (types); the default behavior is
  1095 "type_brackets";
  1096 
  1097 * Pure/syntax: builtin parse translation for "_constify" turns valued
  1098 tokens into AST constants;
  1099 
  1100 * Pure/syntax: prefer later declarations of translations and print
  1101 translation functions; potential INCOMPATIBILITY: need to reverse
  1102 multiple declarations for same syntax element constant;
  1103 
  1104 * Pure/show_hyps reset by default (in accordance to existing Isar
  1105 practice);
  1106 
  1107 * Provers/classical: renamed addaltern to addafter, addSaltern to
  1108 addSafter;
  1109 
  1110 * Provers/clasimp: ``iff'' declarations now handle conditional rules
  1111 as well;
  1112 
  1113 * system: tested support for MacOS X; should be able to get Isabelle +
  1114 Proof General to work in a plain Terminal after installing Poly/ML
  1115 (e.g. from the Isabelle distribution area) and GNU bash alone
  1116 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
  1117 support requires further installations, e.g. from
  1118 http://fink.sourceforge.net/);
  1119 
  1120 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
  1121 
  1122 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
  1123 of 40 MB), cf. ML_OPTIONS;
  1124 
  1125 * system: Proof General keywords specification is now part of the
  1126 Isabelle distribution (see etc/isar-keywords.el);
  1127 
  1128 * system: support for persistent Proof General sessions (refrain from
  1129 outdating all loaded theories on startup); user may create writable
  1130 logic images like this: ``isabelle -q HOL Test'';
  1131 
  1132 * system: smart selection of Isabelle process versus Isabelle
  1133 interface, accommodates case-insensitive file systems (e.g. HFS+); may
  1134 run both "isabelle" and "Isabelle" even if file names are badly
  1135 damaged (executable inspects the case of the first letter of its own
  1136 name); added separate "isabelle-process" and "isabelle-interface";
  1137 
  1138 * system: refrain from any attempt at filtering input streams; no
  1139 longer support ``8bit'' encoding of old isabelle font, instead proper
  1140 iso-latin characters may now be used; the related isatools
  1141 "symbolinput" and "nonascii" have disappeared as well;
  1142 
  1143 * system: removed old "xterm" interface (the print modes "xterm" and
  1144 "xterm_color" are still available for direct use in a suitable
  1145 terminal);
  1146 
  1147 
  1148 
  1149 New in Isabelle99-2 (February 2001)
  1150 -----------------------------------
  1151 
  1152 *** Overview of INCOMPATIBILITIES ***
  1153 
  1154 * HOL: please note that theories in the Library and elsewhere often use the
  1155 new-style (Isar) format; to refer to their theorems in an ML script you must
  1156 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
  1157 
  1158 * HOL: inductive package no longer splits induction rule aggressively,
  1159 but only as far as specified by the introductions given; the old
  1160 format may be recovered via ML function complete_split_rule or attribute
  1161 'split_rule (complete)';
  1162 
  1163 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
  1164 gfp_Tarski to gfp_unfold;
  1165 
  1166 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
  1167 
  1168 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
  1169 relation); infix "^^" has been renamed "``"; infix "``" has been
  1170 renamed "`"; "univalent" has been renamed "single_valued";
  1171 
  1172 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
  1173 operation;
  1174 
  1175 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
  1176 
  1177 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
  1178 
  1179 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
  1180 consequence, it is no longer monotonic wrt. the local goal context
  1181 (which is now passed through the inductive cases);
  1182 
  1183 * Document preparation: renamed standard symbols \<ll> to \<lless> and
  1184 \<gg> to \<ggreater>;
  1185 
  1186 
  1187 *** Document preparation ***
  1188 
  1189 * \isabellestyle{NAME} selects version of Isabelle output (currently
  1190 available: are "it" for near math-mode best-style output, "sl" for
  1191 slanted text style, and "tt" for plain type-writer; if no
  1192 \isabellestyle command is given, output is according to slanted
  1193 type-writer);
  1194 
  1195 * support sub/super scripts (for single symbols only), input syntax is
  1196 like this: "A\<^sup>*" or "A\<^sup>\<star>";
  1197 
  1198 * some more standard symbols; see Appendix A of the system manual for
  1199 the complete list of symbols defined in isabellesym.sty;
  1200 
  1201 * improved isabelle style files; more abstract symbol implementation
  1202 (should now use \isamath{...} and \isatext{...} in custom symbol
  1203 definitions);
  1204 
  1205 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
  1206 state; Note that presentation of goal states does not conform to
  1207 actual human-readable proof documents.  Please do not include goal
  1208 states into document output unless you really know what you are doing!
  1209 
  1210 * proper indentation of antiquoted output with proportional LaTeX
  1211 fonts;
  1212 
  1213 * no_document ML operator temporarily disables LaTeX document
  1214 generation;
  1215 
  1216 * isatool unsymbolize tunes sources for plain ASCII communication;
  1217 
  1218 
  1219 *** Isar ***
  1220 
  1221 * Pure: Isar now suffers initial goal statements to contain unbound
  1222 schematic variables (this does not conform to actual readable proof
  1223 documents, due to unpredictable outcome and non-compositional proof
  1224 checking); users who know what they are doing may use schematic goals
  1225 for Prolog-style synthesis of proven results;
  1226 
  1227 * Pure: assumption method (an implicit finishing) now handles actual
  1228 rules as well;
  1229 
  1230 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
  1231 initial goal, declare "that" only as Pure intro (only for single
  1232 steps); the "that" rule assumption may now be involved in implicit
  1233 finishing, thus ".." becomes a feasible for trivial obtains;
  1234 
  1235 * Pure: default proof step now includes 'intro_classes'; thus trivial
  1236 instance proofs may be performed by "..";
  1237 
  1238 * Pure: ?thesis / ?this / "..." now work for pure meta-level
  1239 statements as well;
  1240 
  1241 * Pure: more robust selection of calculational rules;
  1242 
  1243 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
  1244 rule (as well as the assumption rule);
  1245 
  1246 * Pure: 'thm_deps' command visualizes dependencies of theorems and
  1247 lemmas, using the graph browser tool;
  1248 
  1249 * Pure: predict failure of "show" in interactive mode;
  1250 
  1251 * Pure: 'thms_containing' now takes actual terms as arguments;
  1252 
  1253 * HOL: improved method 'induct' --- now handles non-atomic goals
  1254 (potential INCOMPATIBILITY); tuned error handling;
  1255 
  1256 * HOL: cases and induct rules now provide explicit hints about the
  1257 number of facts to be consumed (0 for "type" and 1 for "set" rules);
  1258 any remaining facts are inserted into the goal verbatim;
  1259 
  1260 * HOL: local contexts (aka cases) may now contain term bindings as
  1261 well; the 'cases' and 'induct' methods new provide a ?case binding for
  1262 the result to be shown in each case;
  1263 
  1264 * HOL: added 'recdef_tc' command;
  1265 
  1266 * isatool convert assists in eliminating legacy ML scripts;
  1267 
  1268 
  1269 *** HOL ***
  1270 
  1271 * HOL/Library: a collection of generic theories to be used together
  1272 with main HOL; the theory loader path already includes this directory
  1273 by default; the following existing theories have been moved here:
  1274 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
  1275 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
  1276 
  1277 * HOL/Unix: "Some aspects of Unix file-system security", a typical
  1278 modelling and verification task performed in Isabelle/HOL +
  1279 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
  1280 
  1281 * HOL/Algebra: special summation operator SUM no longer exists, it has
  1282 been replaced by setsum; infix 'assoc' now has priority 50 (like
  1283 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
  1284 'domain', this makes the theory consistent with mathematical
  1285 literature;
  1286 
  1287 * HOL basics: added overloaded operations "inverse" and "divide"
  1288 (infix "/"), syntax for generic "abs" operation, generic summation
  1289 operator \<Sum>;
  1290 
  1291 * HOL/typedef: simplified package, provide more useful rules (see also
  1292 HOL/subset.thy);
  1293 
  1294 * HOL/datatype: induction rule for arbitrarily branching datatypes is
  1295 now expressed as a proper nested rule (old-style tactic scripts may
  1296 require atomize_strip_tac to cope with non-atomic premises);
  1297 
  1298 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
  1299 to "split_conv" (old name still available for compatibility);
  1300 
  1301 * HOL: improved concrete syntax for strings (e.g. allows translation
  1302 rules with string literals);
  1303 
  1304 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
  1305  and Fleuriot's mechanization of analysis, including the transcendental
  1306  functions for the reals;
  1307 
  1308 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
  1309 
  1310 
  1311 *** CTT ***
  1312 
  1313 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
  1314 "lam" is displayed as TWO lambda-symbols
  1315 
  1316 * CTT: theory Main now available, containing everything (that is, Bool
  1317 and Arith);
  1318 
  1319 
  1320 *** General ***
  1321 
  1322 * Pure: the Simplifier has been implemented properly as a derived rule
  1323 outside of the actual kernel (at last!); the overall performance
  1324 penalty in practical applications is about 50%, while reliability of
  1325 the Isabelle inference kernel has been greatly improved;
  1326 
  1327 * print modes "brackets" and "no_brackets" control output of nested =>
  1328 (types) and ==> (props); the default behaviour is "brackets";
  1329 
  1330 * Provers: fast_tac (and friends) now handle actual object-logic rules
  1331 as assumptions as well;
  1332 
  1333 * system: support Poly/ML 4.0;
  1334 
  1335 * system: isatool install handles KDE version 1 or 2;
  1336 
  1337 
  1338 
  1339 New in Isabelle99-1 (October 2000)
  1340 ----------------------------------
  1341 
  1342 *** Overview of INCOMPATIBILITIES ***
  1343 
  1344 * HOL: simplification of natural numbers is much changed; to partly
  1345 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
  1346 issue the following ML commands:
  1347 
  1348   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
  1349   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
  1350 
  1351 * HOL: simplification no longer dives into case-expressions; this is
  1352 controlled by "t.weak_case_cong" for each datatype t;
  1353 
  1354 * HOL: nat_less_induct renamed to less_induct;
  1355 
  1356 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
  1357 fixsome to patch .thy and .ML sources automatically;
  1358 
  1359   select_equality  -> some_equality
  1360   select_eq_Ex     -> some_eq_ex
  1361   selectI2EX       -> someI2_ex
  1362   selectI2         -> someI2
  1363   selectI          -> someI
  1364   select1_equality -> some1_equality
  1365   Eps_sym_eq       -> some_sym_eq_trivial
  1366   Eps_eq           -> some_eq_trivial
  1367 
  1368 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
  1369 
  1370 * HOL: removed obsolete theorem binding expand_if (refer to split_if
  1371 instead);
  1372 
  1373 * HOL: the recursion equations generated by 'recdef' are now called
  1374 f.simps instead of f.rules;
  1375 
  1376 * HOL: qed_spec_mp now also handles bounded ALL as well;
  1377 
  1378 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  1379 sometimes be needed;
  1380 
  1381 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  1382 
  1383 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  1384 
  1385 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  1386 product is now "<*>" instead of "Times"; the lexicographic product is
  1387 now "<*lex*>" instead of "**";
  1388 
  1389 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  1390 of main HOL, but was unused); better use HOL's datatype package;
  1391 
  1392 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  1393 the old syntax may be recovered as follows:
  1394 
  1395   syntax (symbols)
  1396     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  1397       (infixl "\\<oplus>" 100)
  1398 
  1399 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1400 
  1401 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1402 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1403 internally;
  1404 
  1405 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1406 changed from A/r to A//r;
  1407 
  1408 * ZF: new treatment of arithmetic (nat & int) may break some old
  1409 proofs;
  1410 
  1411 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1412 rulify -> rule_format, elimify -> elim_format, ...);
  1413 
  1414 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1415 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1416 should have to change intro!! to intro? only); replaced "delrule" by
  1417 "rule del";
  1418 
  1419 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1420 
  1421 * Provers: strengthened force_tac by using new first_best_tac;
  1422 
  1423 * LaTeX document preparation: several changes of isabelle.sty (see
  1424 lib/texinputs);
  1425 
  1426 
  1427 *** Document preparation ***
  1428 
  1429 * formal comments (text blocks etc.) in new-style theories may now
  1430 contain antiquotations of thm/prop/term/typ/text to be presented
  1431 according to latex print mode; concrete syntax is like this:
  1432 @{term[show_types] "f(x) = a + x"};
  1433 
  1434 * isatool mkdir provides easy setup of Isabelle session directories,
  1435 including proper document sources;
  1436 
  1437 * generated LaTeX sources are now deleted after successful run
  1438 (isatool document -c); may retain a copy somewhere else via -D option
  1439 of isatool usedir;
  1440 
  1441 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1442 style files, achieving self-contained LaTeX sources and simplifying
  1443 LaTeX debugging;
  1444 
  1445 * old-style theories now produce (crude) LaTeX output as well;
  1446 
  1447 * browser info session directories are now self-contained (may be put
  1448 on WWW server seperately); improved graphs of nested sessions; removed
  1449 graph for 'all sessions';
  1450 
  1451 * several improvements in isabelle style files; \isabellestyle{it}
  1452 produces fake math mode output; \isamarkupheader is now \section by
  1453 default; see lib/texinputs/isabelle.sty etc.;
  1454 
  1455 
  1456 *** Isar ***
  1457 
  1458 * Isar/Pure: local results and corresponding term bindings are now
  1459 subject to Hindley-Milner polymorphism (similar to ML); this
  1460 accommodates incremental type-inference very nicely;
  1461 
  1462 * Isar/Pure: new derived language element 'obtain' supports
  1463 generalized existence reasoning;
  1464 
  1465 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1466 support accumulation of results, without applying any rules yet;
  1467 useful to collect intermediate results without explicit name
  1468 references, and for use with transitivity rules with more than 2
  1469 premises;
  1470 
  1471 * Isar/Pure: scalable support for case-analysis type proofs: new
  1472 'case' language element refers to local contexts symbolically, as
  1473 produced by certain proof methods; internally, case names are attached
  1474 to theorems as "tags";
  1475 
  1476 * Isar/Pure: theory command 'hide' removes declarations from
  1477 class/type/const name spaces;
  1478 
  1479 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1480 indicate potential overloading;
  1481 
  1482 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1483 
  1484 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1485 "{a,b,c}" instead of {a,b,c};
  1486 
  1487 * Isar/Pure now provides its own version of intro/elim/dest
  1488 attributes; useful for building new logics, but beware of confusion
  1489 with the version in Provers/classical;
  1490 
  1491 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1492 case name 'antecedent';
  1493 
  1494 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1495 to the current context is now done automatically);
  1496 
  1497 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1498 for definining proof methods in ML;
  1499 
  1500 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1501 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1502 most cases, one should have to change intro!! to intro? only);
  1503 replaced "delrule" by "rule del";
  1504 
  1505 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1506 'symmetric' attribute (the latter supercedes [RS sym]);
  1507 
  1508 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1509 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1510 well (including splits);
  1511 
  1512 * Isar/Provers: Simplifier and Classical methods now support all kind
  1513 of modifiers used in the past, including 'cong', 'iff', etc.
  1514 
  1515 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1516 of Simplifier and Classical reasoner);
  1517 
  1518 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1519 now support named cases; major packages (inductive, datatype, primrec,
  1520 recdef) support case names and properly name parameters;
  1521 
  1522 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1523 monotonicity conditions are extracted to be proven at end of
  1524 calculations;
  1525 
  1526 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1527 method anyway;
  1528 
  1529 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1530 split_if split_if_asm; datatype package provides theorems foo.splits =
  1531 foo.split foo.split_asm for each datatype;
  1532 
  1533 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1534 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1535 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1536 use "(cases (simplified))" method in proper proof texts);
  1537 
  1538 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1539 
  1540 * Isar: names of theorems etc. may be natural numbers as well;
  1541 
  1542 * Isar: 'pr' command: optional arguments for goals_limit and
  1543 ProofContext.prems_limit; no longer prints theory contexts, but only
  1544 proof states;
  1545 
  1546 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1547 additional print modes to be specified; e.g. "pr(latex)" will print
  1548 proof state according to the Isabelle LaTeX style;
  1549 
  1550 * Isar: improved support for emulating tactic scripts, including proof
  1551 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1552 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1553 (for HOL datatypes);
  1554 
  1555 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1556 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1557 'proof method scripts' have to be in depth-first order;
  1558 
  1559 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1560 
  1561 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1562 should instead use individual commands for printing items
  1563 (print_commands, print_methods etc.);
  1564 
  1565 * Isar: added 'nothing' --- the empty list of theorems;
  1566 
  1567 
  1568 *** HOL ***
  1569 
  1570 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1571 corresponding virtual machine and a specification of its bytecode
  1572 verifier and a lightweight bytecode verifier, including proofs of
  1573 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1574 Cornelia Pusch (see also the homepage of project Bali at
  1575 http://isabelle.in.tum.de/Bali/);
  1576 
  1577 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1578 Clemens Ballarin;
  1579 
  1580 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1581 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1582 Rasmussen;
  1583 
  1584 * HOL/Lattice: fundamental concepts of lattice theory and order
  1585 structures, including duals, properties of bounds versus algebraic
  1586 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1587 Theorem for complete lattices etc.; may also serve as a demonstration
  1588 for abstract algebraic reasoning using axiomatic type classes, and
  1589 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1590 
  1591 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1592 von Oheimb;
  1593 
  1594 * HOL/IMPP: extension of IMP with local variables and mutually
  1595 recursive procedures, by David von Oheimb;
  1596 
  1597 * HOL/Lambda: converted into new-style theory and document;
  1598 
  1599 * HOL/ex/Multiquote: example of multiple nested quotations and
  1600 anti-quotations -- basically a generalized version of de-Bruijn
  1601 representation; very useful in avoiding lifting of operations;
  1602 
  1603 * HOL/record: added general record equality rule to simpset; fixed
  1604 select-update simplification procedure to handle extended records as
  1605 well; admit "r" as field name;
  1606 
  1607 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1608 other numeric types and also as the identity of groups, rings, etc.;
  1609 
  1610 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1611 Types nat and int belong to this axclass;
  1612 
  1613 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1614    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1615    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1616   two terms #m*u and #n*u are replaced by #(m+n)*u
  1617     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1618   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1619     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1620 
  1621 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1622 powerful prover for predicate logic but knows nothing of clasets; see
  1623 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1624 
  1625 * HOL: new version of "case_tac" subsumes both boolean case split and
  1626 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1627 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1628 
  1629 * HOL: simplification no longer dives into case-expressions: only the
  1630 selector expression is simplified, but not the remaining arms; to
  1631 enable full simplification of case-expressions for datatype t, you may
  1632 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1633 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1634 
  1635 * HOL/recdef: the recursion equations generated by 'recdef' for
  1636 function 'f' are now called f.simps instead of f.rules; if all
  1637 termination conditions are proved automatically, these simplification
  1638 rules are added to the simpset, as in primrec; rules may be named
  1639 individually as well, resulting in a separate list of theorems for
  1640 each equation;
  1641 
  1642 * HOL/While is a new theory that provides a while-combinator. It
  1643 permits the definition of tail-recursive functions without the
  1644 provision of a termination measure. The latter is necessary once the
  1645 invariant proof rule for while is applied.
  1646 
  1647 * HOL: new (overloaded) notation for the set of elements below/above
  1648 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1649 
  1650 * HOL: theorems impI, allI, ballI bound as "strip";
  1651 
  1652 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1653 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1654 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1655 
  1656 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1657 
  1658 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1659 main HOL, but was unused);
  1660 
  1661 * HOL: fewer consts declared as global (e.g. have to refer to
  1662 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1663 
  1664 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1665 in case of overlap with user translations (e.g. judgements over
  1666 tuples); (note that the underlying logical represenation is still
  1667 bogus);
  1668 
  1669 
  1670 *** ZF ***
  1671 
  1672 * ZF: simplification automatically cancels common terms in arithmetic
  1673 expressions over nat and int;
  1674 
  1675 * ZF: new treatment of nat to minimize type-checking: all operators
  1676 coerce their operands to a natural number using the function natify,
  1677 making the algebraic laws unconditional;
  1678 
  1679 * ZF: as above, for int: operators coerce their operands to an integer
  1680 using the function intify;
  1681 
  1682 * ZF: the integer library now contains many of the usual laws for the
  1683 orderings, including $<=, and monotonicity laws for $+ and $*;
  1684 
  1685 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1686 simplification;
  1687 
  1688 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1689 to the simplifier and classical reasoner simultaneously;
  1690 
  1691 
  1692 *** General ***
  1693 
  1694 * Provers: blast_tac now handles actual object-logic rules as
  1695 assumptions; note that auto_tac uses blast_tac internally as well;
  1696 
  1697 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1698 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1699 
  1700 * Provers: delrules now handles destruct rules as well (no longer need
  1701 explicit make_elim);
  1702 
  1703 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1704   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1705 use instead the strong form,
  1706   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1707 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1708 from destruct-rules;
  1709 
  1710 * Provers: Simplifier.easy_setup provides a fast path to basic
  1711 Simplifier setup for new object-logics;
  1712 
  1713 * Pure: AST translation rules no longer require constant head on LHS;
  1714 
  1715 * Pure: improved name spaces: ambiguous output is qualified; support
  1716 for hiding of names;
  1717 
  1718 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1719 XSYMBOL_HOME; no longer need to do manual configuration in most
  1720 situations;
  1721 
  1722 * system: compression of ML heaps images may now be controlled via -c
  1723 option of isabelle and isatool usedir (currently only observed by
  1724 Poly/ML);
  1725 
  1726 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1727 useful for remote X11);
  1728 
  1729 * system: provide TAGS file for Isabelle sources;
  1730 
  1731 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1732 order;
  1733 
  1734 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1735 timing flag supersedes proof_timing and Toplevel.trace;
  1736 
  1737 * ML: new combinators |>> and |>>> for incremental transformations
  1738 with secondary results (e.g. certain theory extensions):
  1739 
  1740 * ML: PureThy.add_defs gets additional argument to indicate potential
  1741 overloading (usually false);
  1742 
  1743 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1744 results;
  1745 
  1746 
  1747 
  1748 New in Isabelle99 (October 1999)
  1749 --------------------------------
  1750 
  1751 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1752 
  1753 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1754 are no longer simplified.  (This allows the simplifier to unfold recursive
  1755 functional programs.)  To restore the old behaviour, declare
  1756 
  1757     Delcongs [if_weak_cong];
  1758 
  1759 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1760 complement;
  1761 
  1762 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1763 
  1764 * HOL/datatype: mutual_induct_tac no longer exists --
  1765   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1766 
  1767 * HOL/typedef: fixed type inference for representing set; type
  1768 arguments now have to occur explicitly on the rhs as type constraints;
  1769 
  1770 * ZF: The con_defs part of an inductive definition may no longer refer
  1771 to constants declared in the same theory;
  1772 
  1773 * HOL, ZF: the function mk_cases, generated by the inductive
  1774 definition package, has lost an argument.  To simplify its result, it
  1775 uses the default simpset instead of a supplied list of theorems.
  1776 
  1777 * HOL/List: the constructors of type list are now Nil and Cons;
  1778 
  1779 * Simplifier: the type of the infix ML functions
  1780         setSSolver addSSolver setSolver addSolver
  1781 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1782 for packaging solvers. A solver is created via
  1783         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1784 where the string argument is only a comment.
  1785 
  1786 
  1787 *** Proof tools ***
  1788 
  1789 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1790 decision procedure for linear arithmetic. Currently it is used for
  1791 types `nat', `int', and `real' in HOL (see below); it can, should and
  1792 will be instantiated for other types and logics as well.
  1793 
  1794 * The simplifier now accepts rewrite rules with flexible heads, eg
  1795      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1796   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1797   matching.
  1798 
  1799 
  1800 *** General ***
  1801 
  1802 * New Isabelle/Isar subsystem provides an alternative to traditional
  1803 tactical theorem proving; together with the ProofGeneral/isar user
  1804 interface it offers an interactive environment for developing human
  1805 readable proof documents (Isar == Intelligible semi-automated
  1806 reasoning); for further information see isatool doc isar-ref,
  1807 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1808 
  1809 * improved and simplified presentation of theories: better HTML markup
  1810 (including colors), graph views in several sizes; isatool usedir now
  1811 provides a proper interface for user theories (via -P option); actual
  1812 document preparation based on (PDF)LaTeX is available as well (for
  1813 new-style theories only); see isatool doc system for more information;
  1814 
  1815 * native support for Proof General, both for classic Isabelle and
  1816 Isabelle/Isar;
  1817 
  1818 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1819 using the graph browser tool;
  1820 
  1821 * Isabelle manuals now also available as PDF;
  1822 
  1823 * theory loader rewritten from scratch (may not be fully
  1824 bug-compatible); old loadpath variable has been replaced by show_path,
  1825 add_path, del_path, reset_path functions; new operations such as
  1826 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1827 isatool doc ref);
  1828 
  1829 * improved isatool install: option -k creates KDE application icon,
  1830 option -p DIR installs standalone binaries;
  1831 
  1832 * added ML_PLATFORM setting (useful for cross-platform installations);
  1833 more robust handling of platform specific ML images for SML/NJ;
  1834 
  1835 * the settings environment is now statically scoped, i.e. it is never
  1836 created again in sub-processes invoked from isabelle, isatool, or
  1837 Isabelle;
  1838 
  1839 * path element specification '~~' refers to '$ISABELLE_HOME';
  1840 
  1841 * in locales, the "assumes" and "defines" parts may be omitted if
  1842 empty;
  1843 
  1844 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1845 long arrows);
  1846 
  1847 * new print_mode "HTML";
  1848 
  1849 * new flag show_tags controls display of tags of theorems (which are
  1850 basically just comments that may be attached by some tools);
  1851 
  1852 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1853 mode and goal output format:
  1854 
  1855 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1856 244c244
  1857 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1858 ---
  1859 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1860 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1861 181c181
  1862 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1863 ---
  1864 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1865 
  1866 * function bind_thms stores lists of theorems (cf. bind_thm);
  1867 
  1868 * new shorthand tactics ftac, eatac, datac, fatac;
  1869 
  1870 * qed (and friends) now accept "" as result name; in that case the
  1871 theorem is not stored, but proper checks and presentation of the
  1872 result still apply;
  1873 
  1874 * theorem database now also indexes constants "Trueprop", "all",
  1875 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1876 
  1877 
  1878 *** HOL ***
  1879 
  1880 ** HOL arithmetic **
  1881 
  1882 * There are now decision procedures for linear arithmetic over nat and
  1883 int:
  1884 
  1885 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1886 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1887 are treated as atomic; subformulae not involving type `nat' or `int'
  1888 are ignored; quantified subformulae are ignored unless they are
  1889 positive universal or negative existential. The tactic has to be
  1890 invoked by hand and can be a little bit slow. In particular, the
  1891 running time is exponential in the number of occurrences of `min' and
  1892 `max', and `-' on `nat'.
  1893 
  1894 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1895 (negated) (in)equalities among the premises and the conclusion into
  1896 account (i.e. no compound formulae) and does not know about `min' and
  1897 `max', and `-' on `nat'. It is fast and is used automatically by the
  1898 simplifier.
  1899 
  1900 NB: At the moment, these decision procedures do not cope with mixed
  1901 nat/int formulae where the two parts interact, such as `m < n ==>
  1902 int(m) < int(n)'.
  1903 
  1904 * HOL/Numeral provides a generic theory of numerals (encoded
  1905 efficiently as bit strings); setup for types nat/int/real is in place;
  1906 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1907 int, existing theories and proof scripts may require a few additional
  1908 type constraints;
  1909 
  1910 * integer division and remainder can now be performed on constant
  1911 arguments;
  1912 
  1913 * many properties of integer multiplication, division and remainder
  1914 are now available;
  1915 
  1916 * An interface to the Stanford Validity Checker (SVC) is available through the
  1917 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1918 are proved automatically.  SVC must be installed separately, and its results
  1919 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1920 invocation of the underlying oracle).  For SVC see
  1921   http://verify.stanford.edu/SVC
  1922 
  1923 * IsaMakefile: the HOL-Real target now builds an actual image;
  1924 
  1925 
  1926 ** HOL misc **
  1927 
  1928 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1929 (in Isabelle/Isar) -- by Gertrud Bauer;
  1930 
  1931 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1932 analysis for assembly languages with subtypes;
  1933 
  1934 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1935 -- avoids syntactic ambiguities and treats state, transition, and
  1936 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1937 changed syntax and (many) tactics;
  1938 
  1939 * HOL/inductive: Now also handles more general introduction rules such
  1940   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1941   theorems are now maintained within the theory (maintained via the
  1942   "mono" attribute);
  1943 
  1944 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1945   (using function types) such as
  1946 
  1947   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1948 
  1949 * HOL/record: record_simproc (part of the default simpset) takes care
  1950 of selectors applied to updated records; record_split_tac is no longer
  1951 part of the default claset; update_defs may now be removed from the
  1952 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1953 
  1954   claset_ref () := claset() addSWrapper record_split_wrapper;
  1955   Delsimprocs [record_simproc]
  1956 
  1957 * HOL/typedef: fixed type inference for representing set; type
  1958 arguments now have to occur explicitly on the rhs as type constraints;
  1959 
  1960 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1961 names rather than an ML expression;
  1962 
  1963 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1964 supplied later.  Program schemes can be defined, such as
  1965     "While B C s = (if B s then While B C (C s) else s)"
  1966 where the well-founded relation can be chosen after B and C have been given.
  1967 
  1968 * HOL/List: the constructors of type list are now Nil and Cons;
  1969 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1970 course, ML tools referring to List.list.op # etc. have to be adapted;
  1971 
  1972 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1973 disabled by default; run isabelle with option -m HOL to get back to
  1974 the original Gordon/HOL-style output;
  1975 
  1976 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1977 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1978 
  1979 * HOL basic syntax simplified (more orthogonal): all variants of
  1980 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1981 Eps operator is provided as well: "SOME x. P[x]";
  1982 
  1983 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1984 
  1985 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1986 thus available for user theories;
  1987 
  1988 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1989 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1990 time;
  1991 
  1992 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1993 several times and then mp;
  1994 
  1995 
  1996 *** LK ***
  1997 
  1998 * the notation <<...>> is now available as a notation for sequences of
  1999 formulas;
  2000 
  2001 * the simplifier is now installed
  2002 
  2003 * the axiom system has been generalized (thanks to Soren Heilmann)
  2004 
  2005 * the classical reasoner now has a default rule database
  2006 
  2007 
  2008 *** ZF ***
  2009 
  2010 * new primrec section allows primitive recursive functions to be given
  2011 directly (as in HOL) over datatypes and the natural numbers;
  2012 
  2013 * new tactics induct_tac and exhaust_tac for induction (or case
  2014 analysis) over datatypes and the natural numbers;
  2015 
  2016 * the datatype declaration of type T now defines the recursor T_rec;
  2017 
  2018 * simplification automatically does freeness reasoning for datatype
  2019 constructors;
  2020 
  2021 * automatic type-inference, with AddTCs command to insert new
  2022 type-checking rules;
  2023 
  2024 * datatype introduction rules are now added as Safe Introduction rules
  2025 to the claset;
  2026 
  2027 * the syntax "if P then x else y" is now available in addition to
  2028 if(P,x,y);
  2029 
  2030 
  2031 *** Internal programming interfaces ***
  2032 
  2033 * tuned simplifier trace output; new flag debug_simp;
  2034 
  2035 * structures Vartab / Termtab (instances of TableFun) offer efficient
  2036 tables indexed by indexname_ord / term_ord (compatible with aconv);
  2037 
  2038 * AxClass.axclass_tac lost the theory argument;
  2039 
  2040 * tuned current_goals_markers semantics: begin / end goal avoids
  2041 printing empty lines;
  2042 
  2043 * removed prs and prs_fn hook, which was broken because it did not
  2044 include \n in its semantics, forcing writeln to add one
  2045 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  2046 string -> unit if you really want to output text without newline;
  2047 
  2048 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  2049 plain output, interface builders may have to enable 'isabelle_font'
  2050 mode to get Isabelle font glyphs as before;
  2051 
  2052 * refined token_translation interface; INCOMPATIBILITY: output length
  2053 now of type real instead of int;
  2054 
  2055 * theory loader actions may be traced via new ThyInfo.add_hook
  2056 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  2057 your own database of information attached to *whole* theories -- as
  2058 opposed to intra-theory data slots offered via TheoryDataFun;
  2059 
  2060 * proper handling of dangling sort hypotheses (at last!);
  2061 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  2062 extra sort hypotheses that can be witnessed from the type signature;
  2063 the force_strip_shyps flag is gone, any remaining shyps are simply
  2064 left in the theorem (with a warning issued by strip_shyps_warning);
  2065 
  2066 
  2067 
  2068 New in Isabelle98-1 (October 1998)
  2069 ----------------------------------
  2070 
  2071 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2072 
  2073 * several changes of automated proof tools;
  2074 
  2075 * HOL: major changes to the inductive and datatype packages, including
  2076 some minor incompatibilities of theory syntax;
  2077 
  2078 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  2079 called `inj_on';
  2080 
  2081 * HOL: removed duplicate thms in Arith:
  2082   less_imp_add_less  should be replaced by  trans_less_add1
  2083   le_imp_add_le      should be replaced by  trans_le_add1
  2084 
  2085 * HOL: unary minus is now overloaded (new type constraints may be
  2086 required);
  2087 
  2088 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  2089 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  2090 now taken as an integer constant.
  2091 
  2092 * Pure: ML function 'theory_of' renamed to 'theory';
  2093 
  2094 
  2095 *** Proof tools ***
  2096 
  2097 * Simplifier:
  2098   1. Asm_full_simp_tac is now more aggressive.
  2099      1. It will sometimes reorient premises if that increases their power to
  2100         simplify.
  2101      2. It does no longer proceed strictly from left to right but may also
  2102         rotate premises to achieve further simplification.
  2103      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  2104      old Asm_full_simp_tac in that it does not rotate premises.
  2105   2. The simplifier now knows a little bit about nat-arithmetic.
  2106 
  2107 * Classical reasoner: wrapper mechanism for the classical reasoner now
  2108 allows for selected deletion of wrappers, by introduction of names for
  2109 wrapper functionals.  This implies that addbefore, addSbefore,
  2110 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  2111 and that adding two tactics with the same name overwrites the first
  2112 one (emitting a warning).
  2113   type wrapper = (int -> tactic) -> (int -> tactic)
  2114   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  2115   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  2116   delWrapper, delSWrapper: claset *  string            -> claset
  2117   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  2118 
  2119 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  2120 semantics; addbefore now affects only the unsafe part of step_tac
  2121 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  2122 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  2123 by Force_tac;
  2124 
  2125 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  2126 compWrapper; added safe wrapper (and access functions for it);
  2127 
  2128 * HOL/split_all_tac is now much faster and fails if there is nothing
  2129 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  2130 and the names of the automatically generated variables have changed.
  2131 split_all_tac has moved within claset() from unsafe wrappers to safe
  2132 wrappers, which means that !!-bound variables are split much more
  2133 aggressively, and safe_tac and clarify_tac now split such variables.
  2134 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  2135 Note: the same holds for record_split_tac, which does the job of
  2136 split_all_tac for record fields.
  2137 
  2138 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  2139 permanently to the default simpset using Addsplits just like
  2140 Addsimps. They can be removed via Delsplits just like
  2141 Delsimps. Lower-case versions are also available.
  2142 
  2143 * HOL/Simplifier: The rule split_if is now part of the default
  2144 simpset. This means that the simplifier will eliminate all occurrences
  2145 of if-then-else in the conclusion of a goal. To prevent this, you can
  2146 either remove split_if completely from the default simpset by
  2147 `Delsplits [split_if]' or remove it in a specific call of the
  2148 simplifier using `... delsplits [split_if]'.  You can also add/delete
  2149 other case splitting rules to/from the default simpset: every datatype
  2150 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  2151 t is the name of the datatype).
  2152 
  2153 * Classical reasoner / Simplifier combination: new force_tac (and
  2154 derivatives Force_tac, force) combines rewriting and classical
  2155 reasoning (and whatever other tools) similarly to auto_tac, but is
  2156 aimed to solve the given subgoal completely.
  2157 
  2158 
  2159 *** General ***
  2160 
  2161 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  2162 and `goalw': the theory is no longer needed as an explicit argument -
  2163 the current theory context is used; assumptions are no longer returned
  2164 at the ML-level unless one of them starts with ==> or !!; it is
  2165 recommended to convert to these new commands using isatool fixgoal
  2166 (backup your sources first!);
  2167 
  2168 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  2169 the current theory context, and 'theory' to lookup stored theories;
  2170 
  2171 * new theory section 'locale' for declaring constants, assumptions and
  2172 definitions that have local scope;
  2173 
  2174 * new theory section 'nonterminals' for purely syntactic types;
  2175 
  2176 * new theory section 'setup' for generic ML setup functions
  2177 (e.g. package initialization);
  2178 
  2179 * the distribution now includes Isabelle icons: see
  2180 lib/logo/isabelle-{small,tiny}.xpm;
  2181 
  2182 * isatool install - install binaries with absolute references to
  2183 ISABELLE_HOME/bin;
  2184 
  2185 * isatool logo -- create instances of the Isabelle logo (as EPS);
  2186 
  2187 * print mode 'emacs' reserved for Isamode;
  2188 
  2189 * support multiple print (ast) translations per constant name;
  2190 
  2191 * theorems involving oracles are now printed with a suffixed [!];
  2192 
  2193 
  2194 *** HOL ***
  2195 
  2196 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  2197 
  2198 * HOL/inductive package reorganized and improved: now supports mutual
  2199 definitions such as
  2200 
  2201   inductive EVEN ODD
  2202     intrs
  2203       null "0 : EVEN"
  2204       oddI "n : EVEN ==> Suc n : ODD"
  2205       evenI "n : ODD ==> Suc n : EVEN"
  2206 
  2207 new theorem list "elims" contains an elimination rule for each of the
  2208 recursive sets; inductive definitions now handle disjunctive premises
  2209 correctly (also ZF);
  2210 
  2211 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  2212 "mutual_induct" no longer exists - the induction rule is always
  2213 contained in "induct";
  2214 
  2215 
  2216 * HOL/datatype package re-implemented and greatly improved: now
  2217 supports mutually recursive datatypes such as
  2218 
  2219   datatype
  2220     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  2221             | SUM ('a aexp) ('a aexp)
  2222             | DIFF ('a aexp) ('a aexp)
  2223             | NUM 'a
  2224   and
  2225     'a bexp = LESS ('a aexp) ('a aexp)
  2226             | AND ('a bexp) ('a bexp)
  2227             | OR ('a bexp) ('a bexp)
  2228 
  2229 as well as indirectly recursive datatypes such as
  2230 
  2231   datatype
  2232     ('a, 'b) term = Var 'a
  2233                   | App 'b ((('a, 'b) term) list)
  2234 
  2235 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  2236 induction on mutually / indirectly recursive datatypes.
  2237 
  2238 Primrec equations are now stored in theory and can be accessed via
  2239 <function_name>.simps.
  2240 
  2241 INCOMPATIBILITIES:
  2242 
  2243   - Theories using datatypes must now have theory Datatype as an
  2244     ancestor.
  2245   - The specific <typename>.induct_tac no longer exists - use the
  2246     generic induct_tac instead.
  2247   - natE has been renamed to nat.exhaust - use exhaust_tac
  2248     instead of res_inst_tac ... natE. Note that the variable
  2249     names in nat.exhaust differ from the names in natE, this
  2250     may cause some "fragile" proofs to fail.
  2251   - The theorems split_<typename>_case and split_<typename>_case_asm
  2252     have been renamed to <typename>.split and <typename>.split_asm.
  2253   - Since default sorts of type variables are now handled correctly,
  2254     some datatype definitions may have to be annotated with explicit
  2255     sort constraints.
  2256   - Primrec definitions no longer require function name and type
  2257     of recursive argument.
  2258 
  2259 Consider using isatool fixdatatype to adapt your theories and proof
  2260 scripts to the new package (backup your sources first!).
  2261 
  2262 
  2263 * HOL/record package: considerably improved implementation; now
  2264 includes concrete syntax for record types, terms, updates; theorems
  2265 for surjective pairing and splitting !!-bound record variables; proof
  2266 support is as follows:
  2267 
  2268   1) standard conversions (selectors or updates applied to record
  2269 constructor terms) are part of the standard simpset;
  2270 
  2271   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  2272 made part of standard simpset and claset via addIffs;
  2273 
  2274   3) a tactic for record field splitting (record_split_tac) is part of
  2275 the standard claset (addSWrapper);
  2276 
  2277 To get a better idea about these rules you may retrieve them via
  2278 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  2279 the name of your record type.
  2280 
  2281 The split tactic 3) conceptually simplifies by the following rule:
  2282 
  2283   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  2284 
  2285 Thus any record variable that is bound by meta-all will automatically
  2286 blow up into some record constructor term, consequently the
  2287 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  2288 solve record problems automatically.
  2289 
  2290 
  2291 * reorganized the main HOL image: HOL/Integ and String loaded by
  2292 default; theory Main includes everything;
  2293 
  2294 * automatic simplification of integer sums and comparisons, using cancellation;
  2295 
  2296 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  2297 
  2298 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  2299 
  2300 * many new identities for unions, intersections, set difference, etc.;
  2301 
  2302 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  2303 called split_if, split_split, split_sum_case and split_nat_case (to go
  2304 with add/delsplits);
  2305 
  2306 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  2307 (?x::unit) = (); this is made part of the default simpset, which COULD
  2308 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  2309 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  2310 unit_abs_eta_conv is added in order to counter the effect of
  2311 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  2312 %u.f();
  2313 
  2314 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  2315 makes more sense);
  2316 
  2317 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2318   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2319   disjointness reasoning but breaking a few old proofs.
  2320 
  2321 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  2322 to 'converse' from 'inverse' (for compatibility with ZF and some
  2323 literature);
  2324 
  2325 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  2326 the well-founded relation;
  2327 
  2328 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  2329     Compl A.  The "Compl" syntax remains available as input syntax for this
  2330     release ONLY.
  2331 
  2332 * HOL/Update: new theory of function updates:
  2333     f(a:=b) == %x. if x=a then b else f x
  2334 may also be iterated as in f(a:=b,c:=d,...);
  2335 
  2336 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  2337 
  2338 * HOL/List:
  2339   - new function list_update written xs[i:=v] that updates the i-th
  2340     list position. May also be iterated as in xs[i:=a,j:=b,...].
  2341   - new function `upt' written [i..j(] which generates the list
  2342     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  2343     bound write [i..j], which is a shorthand for [i..j+1(].
  2344   - new lexicographic orderings and corresponding wellfoundedness theorems.
  2345 
  2346 * HOL/Arith:
  2347   - removed 'pred' (predecessor) function;
  2348   - generalized some theorems about n-1;
  2349   - many new laws about "div" and "mod";
  2350   - new laws about greatest common divisors (see theory ex/Primes);
  2351 
  2352 * HOL/Relation: renamed the relational operator r^-1 "converse"
  2353 instead of "inverse";
  2354 
  2355 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  2356   of the multiset ordering;
  2357 
  2358 * directory HOL/Real: a construction of the reals using Dedekind cuts
  2359   (not included by default);
  2360 
  2361 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  2362 
  2363 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  2364   programs, i.e. different program variables may have different types.
  2365 
  2366 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2367   [previously, this check worked only if the rewrite rule was unconditional]
  2368   Now rew can involve either definitions or equalities (either == or =).
  2369 
  2370 
  2371 *** ZF ***
  2372 
  2373 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  2374   only the theorems proved on ZF.ML;
  2375 
  2376 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2377   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2378   disjointness reasoning but breaking a few old proofs.
  2379 
  2380 * ZF/Update: new theory of function updates
  2381     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  2382   may also be iterated as in f(a:=b,c:=d,...);
  2383 
  2384 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  2385 
  2386 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2387   [previously, this check worked only if the rewrite rule was unconditional]
  2388   Now rew can involve either definitions or equalities (either == or =).
  2389 
  2390 * case_tac provided for compatibility with HOL
  2391     (like the old excluded_middle_tac, but with subgoals swapped)
  2392 
  2393 
  2394 *** Internal programming interfaces ***
  2395 
  2396 * Pure: several new basic modules made available for general use, see
  2397 also src/Pure/README;
  2398 
  2399 * improved the theory data mechanism to support encapsulation (data
  2400 kind name replaced by private Object.kind, acting as authorization
  2401 key); new type-safe user interface via functor TheoryDataFun; generic
  2402 print_data function becomes basically useless;
  2403 
  2404 * removed global_names compatibility flag -- all theory declarations
  2405 are qualified by default;
  2406 
  2407 * module Pure/Syntax now offers quote / antiquote translation
  2408 functions (useful for Hoare logic etc. with implicit dependencies);
  2409 see HOL/ex/Antiquote for an example use;
  2410 
  2411 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2412 cterm -> thm;
  2413 
  2414 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2415 subgoal;
  2416 
  2417 * Display.print_goals function moved to Locale.print_goals;
  2418 
  2419 * standard print function for goals supports current_goals_markers
  2420 variable for marking begin of proof, end of proof, start of goal; the
  2421 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2422 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2423 for example;
  2424 
  2425 
  2426 
  2427 New in Isabelle98 (January 1998)
  2428 --------------------------------
  2429 
  2430 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2431 
  2432 * changed lexical syntax of terms / types: dots made part of long
  2433 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2434 
  2435 * simpset (and claset) reference variable replaced by functions
  2436 simpset / simpset_ref;
  2437 
  2438 * no longer supports theory aliases (via merge) and non-trivial
  2439 implicit merge of thms' signatures;
  2440 
  2441 * most internal names of constants changed due to qualified names;
  2442 
  2443 * changed Pure/Sequence interface (see Pure/seq.ML);
  2444 
  2445 
  2446 *** General Changes ***
  2447 
  2448 * hierachically structured name spaces (for consts, types, axms, thms
  2449 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2450 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2451 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2452 long_names for fully qualified output names; NOTE: ML programs
  2453 (special tactics, packages etc.) referring to internal names may have
  2454 to be adapted to cope with fully qualified names; in case of severe
  2455 backward campatibility problems try setting 'global_names' at compile
  2456 time to have enrything declared within a flat name space; one may also
  2457 fine tune name declarations in theories via the 'global' and 'local'
  2458 section;
  2459 
  2460 * reimplemented the implicit simpset and claset using the new anytype
  2461 data filed in signatures; references simpset:simpset ref etc. are
  2462 replaced by functions simpset:unit->simpset and
  2463 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2464 to patch your ML files accordingly;
  2465 
  2466 * HTML output now includes theory graph data for display with Java
  2467 applet or isatool browser; data generated automatically via isatool
  2468 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2469 
  2470 * defs may now be conditional; improved rewrite_goals_tac to handle
  2471 conditional equations;
  2472 
  2473 * defs now admits additional type arguments, using TYPE('a) syntax;
  2474 
  2475 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2476 creates a new theory node; implicit merge of thms' signatures is
  2477 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2478 transfer:theory->thm->thm in (rare) cases;
  2479 
  2480 * improved handling of draft signatures / theories; draft thms (and
  2481 ctyps, cterms) are automatically promoted to real ones;
  2482 
  2483 * slightly changed interfaces for oracles: admit many per theory, named
  2484 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2485 
  2486 * print_goals: optional output of const types (set show_consts and
  2487 show_types);
  2488 
  2489 * improved output of warnings (###) and errors (***);
  2490 
  2491 * subgoal_tac displays a warning if the new subgoal has type variables;
  2492 
  2493 * removed old README and Makefiles;
  2494 
  2495 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2496 
  2497 * removed obsolete init_pps and init_database;
  2498 
  2499 * deleted the obsolete tactical STATE, which was declared by
  2500     fun STATE tacfun st = tacfun st st;
  2501 
  2502 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2503 (which abbreviates $HOME);
  2504 
  2505 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2506 use isatool fixseq to adapt your ML programs (this works for fully
  2507 qualified references to the Sequence structure only!);
  2508 
  2509 * use_thy no longer requires writable current directory; it always
  2510 reloads .ML *and* .thy file, if either one is out of date;
  2511 
  2512 
  2513 *** Classical Reasoner ***
  2514 
  2515 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2516 tactics that use classical reasoning to simplify a subgoal without
  2517 splitting it into several subgoals;
  2518 
  2519 * Safe_tac: like safe_tac but uses the default claset;
  2520 
  2521 
  2522 *** Simplifier ***
  2523 
  2524 * added simplification meta rules:
  2525     (asm_)(full_)simplify: simpset -> thm -> thm;
  2526 
  2527 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2528 logics (again);
  2529 
  2530 * added prems argument to simplification procedures;
  2531 
  2532 * HOL, FOL, ZF: added infix function `addsplits':
  2533   instead of `<simpset> setloop (split_tac <thms>)'
  2534   you can simply write `<simpset> addsplits <thms>'
  2535 
  2536 
  2537 *** Syntax ***
  2538 
  2539 * TYPE('a) syntax for type reflection terms;
  2540 
  2541 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2542 
  2543 * pretty printer: changed order of mixfix annotation preference (again!);
  2544 
  2545 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2546 
  2547 
  2548 *** HOL ***
  2549 
  2550 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2551   with `addloop' of the simplifier to faciliate case splitting in premises.
  2552 
  2553 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2554 
  2555 * HOL/Auth: new protocol proofs including some for the Internet
  2556   protocol TLS;
  2557 
  2558 * HOL/Map: new theory of `maps' a la VDM;
  2559 
  2560 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2561 cancelling out common nat summands from =, <, <= (in)equalities, or
  2562 differences; simplification procedures nat_cancel_factor for
  2563 cancelling common factor from =, <, <= (in)equalities over natural
  2564 sums; nat_cancel contains both kinds of procedures, it is installed by
  2565 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2566 
  2567 * HOL/simplifier: terms of the form
  2568   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2569   are rewritten to
  2570   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2571   and those of the form
  2572   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2573   are rewritten to
  2574   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2575 
  2576 * HOL/datatype
  2577   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2578 
  2579   P(t_case f1 ... fn x) =
  2580      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2581         ...
  2582        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2583      )
  2584 
  2585   and a theorem `split_t_case_asm' of the form
  2586 
  2587   P(t_case f1 ... fn x) =
  2588     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2589         ...
  2590        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2591      )
  2592   which can be added to a simpset via `addsplits'. The existing theorems
  2593   expand_list_case and expand_option_case have been renamed to
  2594   split_list_case and split_option_case.
  2595 
  2596 * HOL/Arithmetic:
  2597   - `pred n' is automatically converted to `n-1'.
  2598     Users are strongly encouraged not to use `pred' any longer,
  2599     because it will disappear altogether at some point.
  2600   - Users are strongly encouraged to write "0 < n" rather than
  2601     "n ~= 0". Theorems and proof tools have been modified towards this
  2602     `standard'.
  2603 
  2604 * HOL/Lists:
  2605   the function "set_of_list" has been renamed "set" (and its theorems too);
  2606   the function "nth" now takes its arguments in the reverse order and
  2607   has acquired the infix notation "!" as in "xs!n".
  2608 
  2609 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2610 
  2611 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2612   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2613 
  2614 * HOL/record: extensible records with schematic structural subtyping
  2615 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2616 still lacks various theorems and concrete record syntax;
  2617 
  2618 
  2619 *** HOLCF ***
  2620 
  2621 * removed "axioms" and "generated by" sections;
  2622 
  2623 * replaced "ops" section by extended "consts" section, which is capable of
  2624   handling the continuous function space "->" directly;
  2625 
  2626 * domain package:
  2627   . proves theorems immediately and stores them in the theory,
  2628   . creates hierachical name space,
  2629   . now uses normal mixfix annotations (instead of cinfix...),
  2630   . minor changes to some names and values (for consistency),
  2631   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2632   . separator between mutual domain defs: changed "," to "and",
  2633   . improved handling of sort constraints;  now they have to
  2634     appear on the left-hand side of the equations only;
  2635 
  2636 * fixed LAM <x,y,zs>.b syntax;
  2637 
  2638 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2639 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2640 
  2641 
  2642 *** FOL and ZF ***
  2643 
  2644 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2645   with `addloop' of the simplifier to faciliate case splitting in premises.
  2646 
  2647 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2648 in HOL, they strip ALL and --> from proved theorems;
  2649 
  2650 
  2651 
  2652 New in Isabelle94-8 (May 1997)
  2653 ------------------------------
  2654 
  2655 *** General Changes ***
  2656 
  2657 * new utilities to build / run / maintain Isabelle etc. (in parts
  2658 still somewhat experimental); old Makefiles etc. still functional;
  2659 
  2660 * new 'Isabelle System Manual';
  2661 
  2662 * INSTALL text, together with ./configure and ./build scripts;
  2663 
  2664 * reimplemented type inference for greater efficiency, better error
  2665 messages and clean internal interface;
  2666 
  2667 * prlim command for dealing with lots of subgoals (an easier way of
  2668 setting goals_limit);
  2669 
  2670 
  2671 *** Syntax ***
  2672 
  2673 * supports alternative (named) syntax tables (parser and pretty
  2674 printer); internal interface is provided by add_modesyntax(_i);
  2675 
  2676 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2677 be used in conjunction with the Isabelle symbol font; uses the
  2678 "symbols" syntax table;
  2679 
  2680 * added token_translation interface (may translate name tokens in
  2681 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2682 the current print_mode); IMPORTANT: user print translation functions
  2683 are responsible for marking newly introduced bounds
  2684 (Syntax.mark_boundT);
  2685 
  2686 * token translations for modes "xterm" and "xterm_color" that display
  2687 names in bold, underline etc. or colors (which requires a color
  2688 version of xterm);
  2689 
  2690 * infixes may now be declared with names independent of their syntax;
  2691 
  2692 * added typed_print_translation (like print_translation, but may
  2693 access type of constant);
  2694 
  2695 
  2696 *** Classical Reasoner ***
  2697 
  2698 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2699 some limitations.  Blast_tac...
  2700   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2701   + ignores elimination rules that don't have the correct format
  2702         (the conclusion MUST be a formula variable)
  2703   + ignores types, which can make HOL proofs fail
  2704   + rules must not require higher-order unification, e.g. apply_type in ZF
  2705     [message "Function Var's argument not a bound variable" relates to this]
  2706   + its proof strategy is more general but can actually be slower
  2707 
  2708 * substitution with equality assumptions no longer permutes other
  2709 assumptions;
  2710 
  2711 * minor changes in semantics of addafter (now called addaltern); renamed
  2712 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2713 (and access functions for it);
  2714 
  2715 * improved combination of classical reasoner and simplifier:
  2716   + functions for handling clasimpsets
  2717   + improvement of addss: now the simplifier is called _after_ the
  2718     safe steps.
  2719   + safe variant of addss called addSss: uses safe simplifications
  2720     _during_ the safe steps. It is more complete as it allows multiple
  2721     instantiations of unknowns (e.g. with slow_tac).
  2722 
  2723 *** Simplifier ***
  2724 
  2725 * added interface for simplification procedures (functions that
  2726 produce *proven* rewrite rules on the fly, depending on current
  2727 redex);
  2728 
  2729 * ordering on terms as parameter (used for ordered rewriting);
  2730 
  2731 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2732 
  2733 * the solver is now split into a safe and an unsafe part.
  2734 This should be invisible for the normal user, except that the
  2735 functions setsolver and addsolver have been renamed to setSolver and
  2736 addSolver; added safe_asm_full_simp_tac;
  2737 
  2738 
  2739 *** HOL ***
  2740 
  2741 * a generic induction tactic `induct_tac' which works for all datatypes and
  2742 also for type `nat';
  2743 
  2744 * a generic case distinction tactic `exhaust_tac' which works for all
  2745 datatypes and also for type `nat';
  2746 
  2747 * each datatype comes with a function `size';
  2748 
  2749 * patterns in case expressions allow tuple patterns as arguments to
  2750 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2751 
  2752 * primrec now also works with type nat;
  2753 
  2754 * recdef: a new declaration form, allows general recursive functions to be
  2755 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2756 
  2757 * the constant for negation has been renamed from "not" to "Not" to
  2758 harmonize with FOL, ZF, LK, etc.;
  2759 
  2760 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2761 infinite lists;
  2762 
  2763 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2764 
  2765 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2766 problems in commutative rings, using axiomatic type classes for + and *;
  2767 
  2768 * more examples in HOL/MiniML and HOL/Auth;
  2769 
  2770 * more default rewrite rules for quantifiers, union/intersection;
  2771 
  2772 * a new constant `arbitrary == @x.False';
  2773 
  2774 * HOLCF/IOA replaces old HOL/IOA;
  2775 
  2776 * HOLCF changes: derived all rules and arities
  2777   + axiomatic type classes instead of classes
  2778   + typedef instead of faking type definitions
  2779   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2780   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2781   + eliminated the types void, one, tr
  2782   + use unit lift and bool lift (with translations) instead of one and tr
  2783   + eliminated blift from Lift3.thy (use Def instead of blift)
  2784   all eliminated rules are derived as theorems --> no visible changes ;
  2785 
  2786 
  2787 *** ZF ***
  2788 
  2789 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2790 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2791 as ZF_cs addSIs [equalityI];
  2792 
  2793 
  2794 
  2795 New in Isabelle94-7 (November 96)
  2796 ---------------------------------
  2797 
  2798 * allowing negative levels (as offsets) in prlev and choplev;
  2799 
  2800 * super-linear speedup for large simplifications;
  2801 
  2802 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2803 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2804 FAIL); can suppress it using the command Delsimps (ex_simps @
  2805 all_simps); De Morgan laws are also now included, by default;
  2806 
  2807 * improved printing of ==>  :  ~:
  2808 
  2809 * new object-logic "Sequents" adds linear logic, while replacing LK
  2810 and Modal (thanks to Sara Kalvala);
  2811 
  2812 * HOL/Auth: correctness proofs for authentication protocols;
  2813 
  2814 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2815 examples on HOL/Auth);
  2816 
  2817 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2818 the rewriter and classical reasoner simultaneously;
  2819 
  2820 * function uresult no longer returns theorems in "standard" format;
  2821 regain previous version by: val uresult = standard o uresult;
  2822 
  2823 
  2824 
  2825 New in Isabelle94-6
  2826 -------------------
  2827 
  2828 * oracles -- these establish an interface between Isabelle and trusted
  2829 external reasoners, which may deliver results as theorems;
  2830 
  2831 * proof objects (in particular record all uses of oracles);
  2832 
  2833 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2834 
  2835 * "constdefs" section in theory files;
  2836 
  2837 * "primrec" section (HOL) no longer requires names;
  2838 
  2839 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2840 
  2841 
  2842 
  2843 New in Isabelle94-5
  2844 -------------------
  2845 
  2846 * reduced space requirements;
  2847 
  2848 * automatic HTML generation from theories;
  2849 
  2850 * theory files no longer require "..." (quotes) around most types;
  2851 
  2852 * new examples, including two proofs of the Church-Rosser theorem;
  2853 
  2854 * non-curried (1994) version of HOL is no longer distributed;
  2855 
  2856 
  2857 
  2858 New in Isabelle94-4
  2859 -------------------
  2860 
  2861 * greatly reduced space requirements;
  2862 
  2863 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2864 
  2865 * searchable theorem database (see the section "Retrieving theorems" on
  2866 page 8 of the Reference Manual);
  2867 
  2868 * new examples, including Grabczewski's monumental case study of the
  2869 Axiom of Choice;
  2870 
  2871 * The previous version of HOL renamed to Old_HOL;
  2872 
  2873 * The new version of HOL (previously called CHOL) uses a curried syntax
  2874 for functions.  Application looks like f a b instead of f(a,b);
  2875 
  2876 * Mutually recursive inductive definitions finally work in HOL;
  2877 
  2878 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2879 translates to the operator "split";
  2880 
  2881 
  2882 
  2883 New in Isabelle94-3
  2884 -------------------
  2885 
  2886 * new infix operator, addss, allowing the classical reasoner to
  2887 perform simplification at each step of its search.  Example:
  2888         fast_tac (cs addss ss)
  2889 
  2890 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2891 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2892 look like (a,b) instead of <a,b>;
  2893 
  2894 * PLEASE NOTE: CHOL will eventually replace HOL!
  2895 
  2896 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2897 It translates to the operator "split".  A new theory of integers is available;
  2898 
  2899 * In ZF, integer numerals now denote two's-complement binary integers.
  2900 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2901 
  2902 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2903 of the Axiom of Choice;
  2904 
  2905 
  2906 
  2907 New in Isabelle94-2
  2908 -------------------
  2909 
  2910 * Significantly faster resolution;
  2911 
  2912 * the different sections in a .thy file can now be mixed and repeated
  2913 freely;
  2914 
  2915 * Database of theorems for FOL, HOL and ZF.  New
  2916 commands including qed, qed_goal and bind_thm store theorems in the database.
  2917 
  2918 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2919 a given theory (thms_of), or find out what theory a theorem was proved in
  2920 (theory_of_thm);
  2921 
  2922 * Bugs fixed in the inductive definition and datatype packages;
  2923 
  2924 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2925 and HOL_dup_cs obsolete;
  2926 
  2927 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2928 have been removed;
  2929 
  2930 * Simpler definition of function space in ZF;
  2931 
  2932 * new results about cardinal and ordinal arithmetic in ZF;
  2933 
  2934 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2935 types;
  2936 
  2937 
  2938 $Id$