NEWS
author paulson
Tue Feb 01 18:01:57 2005 +0100 (2005-02-01)
changeset 15481 fc075ae929e4
parent 15477 5058984779b9
child 15528 1b12557f720d
permissions -rw-r--r--
the new subst tactic, by Lucas Dixon
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** General ***
     8 
     9 * Document preparation: new antiquotations @{lhs thm} and @{rhs thm}
    10   printing the lhs/rhs of definitions, equations, inequations etc. 
    11 
    12 * isatool usedir: new option -f that allows specification of the ML
    13   file to be used by Isabelle; default is ROOT.ML.
    14 
    15 * Theory headers: the new header syntax for Isar theories is
    16 
    17   theory <name>
    18   imports <theory1> ... <theoryn>
    19   begin
    20 
    21   optionally also with a "files" section. The syntax
    22 
    23   theory <name> = <theory1> + ... + <theoryn>:
    24 
    25   will still be supported for some time but will eventually disappear.
    26   The syntax of old-style theories has not changed.
    27 
    28 * Theory loader: parent theories can now also be referred to via
    29   relative and absolute paths.
    30 
    31 * Provers/quasi.ML:  new transitivity reasoners for transitivity only
    32   and quasi orders.
    33 
    34 * Provers/trancl.ML:  new transitivity reasoner for transitive and
    35   reflexive-transitive closure of relations.
    36 
    37 * Provers/blast.ML:  new reference depth_limit to make blast's depth
    38   limit (previously hard-coded with a value of 20) user-definable.
    39 
    40 * Provers: new version of the subst method, for single-step rewriting: it now
    41   works in bound variable contexts. New is subst (asm), for rewriting an
    42   assumption. Thanks to Lucas Dixon! INCOMPATIBILITY: may rewrite a different
    43   subterm than the original subst method, which is still available under the
    44   name simplesubst.
    45 
    46 * Pure: thin_tac now works even if the assumption being deleted contains !! or ==>. 
    47   More generally, erule now works even if the major premise of the elimination rule
    48   contains !! or ==>.
    49 
    50 * Pure: considerably improved version of 'constdefs' command.  Now
    51   performs automatic type-inference of declared constants; additional
    52   support for local structure declarations (cf. locales and HOL
    53   records), see also isar-ref manual.  Potential INCOMPATIBILITY: need
    54   to observe strictly sequential dependencies of definitions within a
    55   single 'constdefs' section; moreover, the declared name needs to be
    56   an identifier.  If all fails, consider to fall back on 'consts' and
    57   'defs' separately.
    58 
    59 * Pure: improved indexed syntax and implicit structures.  First of
    60   all, indexed syntax provides a notational device for subscripted
    61   application, using the new syntax \<^bsub>term\<^esub> for arbitrary
    62   expressions.  Secondly, in a local context with structure
    63   declarations, number indexes \<^sub>n or the empty index (default
    64   number 1) refer to a certain fixed variable implicitly; option
    65   show_structs controls printing of implicit structures.  Typical
    66   applications of these concepts involve record types and locales.
    67 
    68 * Pure: clear separation of logical types and nonterminals, where the
    69   latter may only occur in 'syntax' specifications or type
    70   abbreviations.  Before that distinction was only partially
    71   implemented via type class "logic" vs. "{}".  Potential
    72   INCOMPATIBILITY in rare cases of improper use of 'types'/'consts'
    73   instead of 'nonterminals'/'syntax'.  Some very exotic syntax
    74   specifications may require further adaption (e.g. Cube/Base.thy).
    75 
    76 * Pure: removed obsolete type class "logic", use the top sort {}
    77   instead.  Note that non-logical types should be declared as
    78   'nonterminals' rather than 'types'.  INCOMPATIBILITY for new
    79   object-logic specifications.
    80 
    81 * Pure: print_tac now outputs the goal through the trace channel.
    82 
    83 * Pure: reference Namespace.unique_names included.  If true the
    84   (shortest) namespace-prefix is printed to disambiguate conflicts (as
    85   yet). If false the first entry wins (as during parsing). Default
    86   value is true.
    87 
    88 * Pure: tuned internal renaming of symbolic identifiers -- attach
    89   primes instead of base 26 numbers.
    90 
    91 * Pure: new flag show_var_qmarks to control printing of leading
    92   question marks of variable names.
    93 
    94 * Pure/Syntax: inner syntax includes (*(*nested*) comments*).
    95 
    96 * Pure/Syntax: pretty pinter now supports unbreakable blocks,
    97   specified in mixfix annotations as "(00...)".
    98 
    99 * Pure/Syntax: 'advanced' translation functions (parse_translation
   100   etc.) may depend on the signature of the theory context being
   101   presently used for parsing/printing, see also isar-ref manual.
   102 
   103 * Pure/Simplifier: simplification procedures may now take the current
   104   simpset into account (cf. Simplifier.simproc(_i) / mk_simproc
   105   interface), which is very useful for calling the Simplifier
   106   recursively.  Minor INCOMPATIBILITY: the 'prems' argument of
   107   simprocs is gone -- use prems_of_ss on the simpset instead.
   108   Moreover, the low-level mk_simproc no longer applies Logic.varify
   109   internally, to allow for use in a context of fixed variables.
   110 
   111 * Pure/Simplifier: Command "find_rewrites" takes a string and lists all
   112   equality theorems (not just those with attribute simp!) whose left-hand
   113   side matches the term given via the string. In PG the command can be
   114   activated via Isabelle -> Show me -> matching rewrites.
   115 
   116 * Provers: Simplifier and Classical Reasoner now support proof context
   117   dependent plug-ins (simprocs, solvers, wrappers etc.).  These extra
   118   components are stored in the theory and patched into the
   119   simpset/claset when used in an Isar proof context.  Context
   120   dependent components are maintained by the following theory
   121   operations:
   122 
   123     Simplifier.add_context_simprocs
   124     Simplifier.del_context_simprocs
   125     Simplifier.set_context_subgoaler
   126     Simplifier.reset_context_subgoaler
   127     Simplifier.add_context_looper
   128     Simplifier.del_context_looper
   129     Simplifier.add_context_unsafe_solver
   130     Simplifier.add_context_safe_solver
   131 
   132     Classical.add_context_safe_wrapper
   133     Classical.del_context_safe_wrapper
   134     Classical.add_context_unsafe_wrapper
   135     Classical.del_context_unsafe_wrapper
   136 
   137   IMPORTANT NOTE: proof tools (methods etc.) need to use
   138   local_simpset_of and local_claset_of to instead of the primitive
   139   Simplifier.get_local_simpset and Classical.get_local_claset,
   140   respectively, in order to see the context dependent fields!
   141 
   142 * Document preparation: antiquotations now provide the option
   143   'locale=NAME' to specify an alternative context used for evaluating
   144   and printing the subsequent argument, as in @{thm [locale=LC]
   145   fold_commute}, for example.
   146 
   147 * Document preparation: commands 'display_drafts' and 'print_drafts'
   148   perform simple output of raw sources.  Only those symbols that do
   149   not require additional LaTeX packages (depending on comments in
   150   isabellesym.sty) are displayed properly, everything else is left
   151   verbatim.  We use isatool display and isatool print as front ends;
   152   these are subject to the DVI_VIEWER and PRINT_COMMAND settings,
   153   respectively.
   154 
   155 * Document preparation: Proof scripts as well as some other commands
   156   such as ML or parse/print_translation can now be hidden in the document.
   157   Hiding is enabled by default, and can be disabled either via the option
   158   '-H false' of isatool usedir or by resetting the reference variable
   159   IsarOutput.hide_commands. Additional commands to be hidden may be
   160   declared using IsarOutput.add_hidden_commands.
   161 
   162 * ML: output via the Isabelle channels of writeln/warning/error
   163   etc. is now passed through Output.output, with a hook for arbitrary
   164   transformations depending on the print_mode (cf. Output.add_mode --
   165   the first active mode that provides a output function wins).
   166   Already formatted output may be embedded into further text via
   167   Output.raw; the result of Pretty.string_of/str_of and derived
   168   functions (string_of_term/cterm/thm etc.) is already marked raw to
   169   accommodate easy composition of diagnostic messages etc.
   170   Programmers rarely need to care about Output.output or Output.raw at
   171   all, with some notable exceptions: Output.output is required when
   172   bypassing the standard channels (writeln etc.), or in token
   173   translations to produce properly formatted results; Output.raw is
   174   required when capturing already output material that will eventually
   175   be presented to the user a second time.  For the default print mode,
   176   both Output.output and Output.raw have no effect.
   177 
   178 
   179 *** Isar ***
   180 
   181 * Locales:
   182   - "includes" disallowed in declaration of named locales (command "locale").
   183   - Fixed parameter management in theorem generation for goals with "includes".
   184     INCOMPATIBILITY: rarely, the generated theorem statement is different.
   185 
   186 * New syntax
   187 
   188     <theorem_name> (<index>, ..., <index>-<index>, ...)
   189 
   190   for referring to specific theorems in a named list of theorems via
   191   indices.
   192 
   193 *** HOL ***
   194 
   195 * Datatype induction via method `induct' now preserves the name of the
   196   induction variable. For example, when proving P(xs::'a list) by induction
   197   on xs, the induction step is now P(xs) ==> P(a#xs) rather than
   198   P(list) ==> P(a#list) as previously.
   199 
   200 * HOL/record: reimplementation of records. Improved scalability for
   201   records with many fields, avoiding performance problems for type
   202   inference. Records are no longer composed of nested field types, but
   203   of nested extension types. Therefore the record type only grows
   204   linear in the number of extensions and not in the number of fields.
   205   The top-level (users) view on records is preserved.  Potential
   206   INCOMPATIBILITY only in strange cases, where the theory depends on
   207   the old record representation. The type generated for a record is
   208   called <record_name>_ext_type.
   209 
   210 * HOL/record: Reference record_quick_and_dirty_sensitive can be
   211   enabled to skip the proofs triggered by a record definition or a
   212   simproc (if quick_and_dirty is enabled). Definitions of large
   213   records can take quite long.
   214 
   215 * HOL/record: "record_upd_simproc" for simplification of multiple
   216   record updates enabled by default.  Moreover, trivial updates are
   217   also removed: r(|x := x r|) = r.  INCOMPATIBILITY: old proofs break
   218   occasionally, since simplification is more powerful by default.
   219 
   220 * HOL: symbolic syntax of Hilbert Choice Operator is now as follows:
   221 
   222   syntax (epsilon)
   223     "_Eps" :: "[pttrn, bool] => 'a"    ("(3\<some>_./ _)" [0, 10] 10)
   224 
   225   The symbol \<some> is displayed as the alternative epsilon of LaTeX
   226   and x-symbol; use option '-m epsilon' to get it actually printed.
   227   Moreover, the mathematically important symbolic identifier
   228   \<epsilon> becomes available as variable, constant etc.
   229 
   230 * HOL: "x > y" abbreviates "y < x" and "x >= y" abbreviates "y <= x".
   231   Similarly for all quantifiers: "ALL x > y" etc.
   232   The x-symbol for >= is \<ge>.
   233 
   234 * HOL/SetInterval: The syntax for open intervals has changed:
   235 
   236   Old         New
   237   {..n(}   -> {..<n}
   238   {)n..}   -> {n<..}
   239   {m..n(}  -> {m..<n}
   240   {)m..n}  -> {m<..n}
   241   {)m..n(} -> {m<..<n}
   242 
   243   The old syntax is still supported but will disappear in the future.
   244   For conversion use the following emacs search and replace patterns:
   245 
   246   {)\([^\.]*\)\.\.  ->  {\1<\.\.}
   247   \.\.\([^(}]*\)(}  ->  \.\.<\1}
   248 
   249   They are not perfect but work quite well.
   250 
   251 * HOL: The syntax for 'setsum', summation over finite sets, has changed:
   252 
   253   The syntax for 'setsum (%x. e) A' used to be '\<Sum>x:A. e'
   254   and is now either 'SUM x:A. e' or '\<Sum>x\<in>A. e'.
   255 
   256   There is new syntax for summation over finite sets:
   257 
   258   '\<Sum>x | P. e'    is the same as  'setsum (%x. e) {x. P}'
   259   '\<Sum>x=a..b. e'   is the same as  'setsum (%x. e) {a..b}'
   260   '\<Sum>x=a..<b. e'  is the same as  'setsum (%x. e) {a..<b}'
   261   '\<Sum>x<k. e'      is the same as  'setsum (%x. e) {..<k}'
   262 
   263   Function 'Summation' over nat is gone, its syntax '\<Sum>i<k. e'
   264   now translates into 'setsum' as above.
   265 
   266 * HOL: Finite set induction: In Isar proofs, the insert case is now
   267   "case (insert x F)" instead of the old counterintuitive "case (insert F x)".
   268 
   269 * HOL/Simplifier:
   270 
   271   - Is now set up to reason about transitivity chains involving "trancl"
   272   (r^+) and "rtrancl" (r^*) by setting up tactics provided by
   273   Provers/trancl.ML as additional solvers.  INCOMPATIBILITY: old proofs break
   274   occasionally as simplification may now solve more goals than previously.
   275 
   276   - Converts x <= y into x = y if assumption y <= x is present.  Works for
   277   all partial orders (class "order"), in particular numbers and sets. For
   278   linear orders (e.g. numbers) it treats ~ x < y just like y <= x.
   279 
   280   - Simproc for "let x = a in f x"
   281   If a is a free or bound variable or a constant then the let is unfolded.
   282   Otherwise first a is simplified to a', and then f a' is simplified to
   283   g. If possible we abstract a' from g arriving at "let x = a' in g' x",
   284   otherwise we unfold the let and arrive at g. The simproc can be 
   285   enabled/disabled by the reference use_let_simproc. Potential
   286   INCOMPATIBILITY since simplification is more powerful by default.
   287  
   288 * HOL: new 'isatool dimacs2hol' to convert files in DIMACS CNF format
   289   (containing Boolean satisfiability problems) into Isabelle/HOL theories.
   290 
   291 
   292 *** HOLCF ***
   293 
   294 * HOLCF: discontinued special version of 'constdefs' (which used to
   295   support continuous functions) in favor of the general Pure one with
   296   full type-inference.
   297 
   298 
   299 *** ZF ***
   300 
   301 * ZF/ex/{Group,Ring}: examples in abstract algebra, including the
   302   First Isomorphism Theorem (on quotienting by the kernel of a
   303   homomorphism).
   304 
   305 * ZF/Simplifier: install second copy of type solver that actually
   306   makes use of TC rules declared to Isar proof contexts (or locales);
   307   the old version is still required for ML proof scripts.
   308 
   309 
   310 
   311 New in Isabelle2004 (April 2004)
   312 --------------------------------
   313 
   314 *** General ***
   315 
   316 * Provers/order.ML:  new efficient reasoner for partial and linear orders.
   317   Replaces linorder.ML.
   318 
   319 * Pure: Greek letters (except small lambda, \<lambda>), as well as Gothic
   320   (\<aa>...\<zz>\<AA>...\<ZZ>), calligraphic (\<A>...\<Z>), and Euler
   321   (\<a>...\<z>), are now considered normal letters, and can therefore
   322   be used anywhere where an ASCII letter (a...zA...Z) has until
   323   now. COMPATIBILITY: This obviously changes the parsing of some
   324   terms, especially where a symbol has been used as a binder, say
   325   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed
   326   as an identifier.  Fix it by inserting a space around former
   327   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in
   328   existing theory and ML files.
   329 
   330 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.
   331 
   332 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now
   333   allowed in identifiers. Similar to Greek letters \<^isub> is now considered
   334   a normal (but invisible) letter. For multiple letter subscripts repeat
   335   \<^isub> like this: x\<^isub>1\<^isub>2.
   336 
   337 * Pure: There are now sub-/superscripts that can span more than one
   338   character. Text between \<^bsub> and \<^esub> is set in subscript in
   339   ProofGeneral and LaTeX, text between \<^bsup> and \<^esup> in
   340   superscript. The new control characters are not identifier parts.
   341 
   342 * Pure: Control-symbols of the form \<^raw:...> will literally print the
   343   content of "..." to the latex file instead of \isacntrl... . The "..."
   344   may consist of any printable characters excluding the end bracket >.
   345 
   346 * Pure: Using new Isar command "finalconsts" (or the ML functions
   347   Theory.add_finals or Theory.add_finals_i) it is now possible to
   348   declare constants "final", which prevents their being given a definition
   349   later.  It is useful for constants whose behaviour is fixed axiomatically
   350   rather than definitionally, such as the meta-logic connectives.
   351 
   352 * Pure: 'instance' now handles general arities with general sorts
   353   (i.e. intersections of classes),
   354 
   355 * Presentation: generated HTML now uses a CSS style sheet to make layout
   356   (somewhat) independent of content. It is copied from lib/html/isabelle.css.
   357   It can be changed to alter the colors/layout of generated pages.
   358 
   359 
   360 *** Isar ***
   361 
   362 * Tactic emulation methods rule_tac, erule_tac, drule_tac, frule_tac,
   363   cut_tac, subgoal_tac and thin_tac:
   364   - Now understand static (Isar) contexts.  As a consequence, users of Isar
   365     locales are no longer forced to write Isar proof scripts.
   366     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
   367     emulations.
   368   - INCOMPATIBILITY: names of variables to be instantiated may no
   369     longer be enclosed in quotes.  Instead, precede variable name with `?'.
   370     This is consistent with the instantiation attribute "where".
   371 
   372 * Attributes "where" and "of":
   373   - Now take type variables of instantiated theorem into account when reading
   374     the instantiation string.  This fixes a bug that caused instantiated
   375     theorems to have too special types in some circumstances.
   376   - "where" permits explicit instantiations of type variables.
   377 
   378 * Calculation commands "moreover" and "also" no longer interfere with
   379   current facts ("this"), admitting arbitrary combinations with "then"
   380   and derived forms.
   381 
   382 * Locales:
   383   - Goal statements involving the context element "includes" no longer
   384     generate theorems with internal delta predicates (those ending on
   385     "_axioms") in the premise.
   386     Resolve particular premise with <locale>.intro to obtain old form.
   387   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
   388     specification and "includes" elements in goal statement.
   389   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
   390     [intro?] and [elim?] (respectively) by default.
   391   - Experimental command for instantiation of locales in proof contexts:
   392         instantiate <label>[<attrs>]: <loc>
   393     Instantiates locale <loc> and adds all its theorems to the current context
   394     taking into account their attributes.  Label and attrs are optional
   395     modifiers, like in theorem declarations.  If present, names of
   396     instantiated theorems are qualified with <label>, and the attributes
   397     <attrs> are applied after any attributes these theorems might have already.
   398       If the locale has assumptions, a chained fact of the form
   399     "<loc> t1 ... tn" is expected from which instantiations of the parameters
   400     are derived.  The command does not support old-style locales declared
   401     with "locale (open)".
   402       A few (very simple) examples can be found in FOL/ex/LocaleInst.thy.
   403 
   404 * HOL: Tactic emulation methods induct_tac and case_tac understand static
   405   (Isar) contexts.
   406 
   407 
   408 *** HOL ***
   409 
   410 * Proof import: new image HOL4 contains the imported library from
   411   the HOL4 system with about 2500 theorems. It is imported by
   412   replaying proof terms produced by HOL4 in Isabelle. The HOL4 image
   413   can be used like any other Isabelle image.  See
   414   HOL/Import/HOL/README for more information.
   415 
   416 * Simplifier:
   417   - Much improved handling of linear and partial orders.
   418     Reasoners for linear and partial orders are set up for type classes
   419     "linorder" and "order" respectively, and are added to the default simpset
   420     as solvers.  This means that the simplifier can build transitivity chains
   421     to solve goals from the assumptions.
   422   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications
   423     of blast or auto after simplification become unnecessary because the goal
   424     is solved by simplification already.
   425 
   426 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws,
   427     all proved in axiomatic type classes for semirings, rings and fields.
   428 
   429 * Numerics:
   430   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are
   431     now formalized using the Ring_and_Field theory mentioned above.
   432   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently
   433     than before, because now they are set up once in a generic manner.
   434   - INCOMPATIBILITY: many type-specific arithmetic laws have gone.
   435     Look for the general versions in Ring_and_Field (and Power if they concern
   436     exponentiation).
   437 
   438 * Type "rat" of the rational numbers is now available in HOL-Complex.
   439 
   440 * Records:
   441   - Record types are now by default printed with their type abbreviation
   442     instead of the list of all field types. This can be configured via
   443     the reference "print_record_type_abbr".
   444   - Simproc "record_upd_simproc" for simplification of multiple updates added
   445     (not enabled by default).
   446   - Simproc "record_ex_sel_eq_simproc" to simplify EX x. sel r = x resp.
   447     EX x. x = sel r to True (not enabled by default).
   448   - Tactic "record_split_simp_tac" to split and simplify records added.
   449 
   450 * 'specification' command added, allowing for definition by
   451   specification.  There is also an 'ax_specification' command that
   452   introduces the new constants axiomatically.
   453 
   454 * arith(_tac) is now able to generate counterexamples for reals as well.
   455 
   456 * HOL-Algebra: new locale "ring" for non-commutative rings.
   457 
   458 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
   459   definitions, thanks to Sava Krsti\'{c} and John Matthews.
   460 
   461 * HOL-Matrix: a first theory for matrices in HOL with an application of
   462   matrix theory to linear programming.
   463 
   464 * Unions and Intersections:
   465   The latex output syntax of UN and INT has been changed
   466   from "\Union x \in A. B" to "\Union_{x \in A} B"
   467   i.e. the index formulae has become a subscript.
   468   Similarly for "\Union x. B", and for \Inter instead of \Union.
   469 
   470 * Unions and Intersections over Intervals:
   471   There is new short syntax "UN i<=n. A" for "UN i:{0..n}. A". There is
   472   also an x-symbol version with subscripts "\<Union>\<^bsub>i <= n\<^esub>. A"
   473   like in normal math, and corresponding versions for < and for intersection.
   474 
   475 * ML: the legacy theory structures Int and List have been removed. They had
   476   conflicted with ML Basis Library structures having the same names.
   477 
   478 * 'refute' command added to search for (finite) countermodels.  Only works
   479   for a fragment of HOL.  The installation of an external SAT solver is
   480   highly recommended.  See "HOL/Refute.thy" for details.
   481 
   482 * 'quickcheck' command: Allows to find counterexamples by evaluating
   483   formulae under an assignment of free variables to random values.
   484   In contrast to 'refute', it can deal with inductive datatypes,
   485   but cannot handle quantifiers. See "HOL/ex/Quickcheck_Examples.thy"
   486   for examples.
   487 
   488 
   489 *** HOLCF ***
   490 
   491 * Streams now come with concatenation and are part of the HOLCF image
   492 
   493 
   494 
   495 New in Isabelle2003 (May 2003)
   496 ------------------------------
   497 
   498 *** General ***
   499 
   500 * Provers/simplifier:
   501 
   502   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   503     Assumptions are now subject to complete mutual simplification,
   504     not just from left to right. The simplifier now preserves
   505     the order of assumptions.
   506 
   507     Potential INCOMPATIBILITY:
   508 
   509     -- simp sometimes diverges where the old version did
   510        not, e.g. invoking simp on the goal
   511 
   512         [| P (f x); y = x; f x = f y |] ==> Q
   513 
   514        now gives rise to the infinite reduction sequence
   515 
   516         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   517 
   518        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   519        kind of problem.
   520 
   521     -- Tactics combining classical reasoner and simplification (such as auto)
   522        are also affected by this change, because many of them rely on
   523        simp. They may sometimes diverge as well or yield a different numbers
   524        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   525        in case of problems. Sometimes subsequent calls to the classical
   526        reasoner will fail because a preceeding call to the simplifier too
   527        eagerly simplified the goal, e.g. deleted redundant premises.
   528 
   529   - The simplifier trace now shows the names of the applied rewrite rules
   530 
   531   - You can limit the number of recursive invocations of the simplifier
   532     during conditional rewriting (where the simplifie tries to solve the
   533     conditions before applying the rewrite rule):
   534     ML "simp_depth_limit := n"
   535     where n is an integer. Thus you can force termination where previously
   536     the simplifier would diverge.
   537 
   538   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   539 
   540   - No longer aborts on failed congruence proof.  Instead, the
   541     congruence is ignored.
   542 
   543 * Pure: New generic framework for extracting programs from constructive
   544   proofs. See HOL/Extraction.thy for an example instantiation, as well
   545   as HOL/Extraction for some case studies.
   546 
   547 * Pure: The main goal of the proof state is no longer shown by default, only
   548 the subgoals. This behaviour is controlled by a new flag.
   549    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   550 (ML: Proof.show_main_goal).
   551 
   552 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   553 rules whose conclusion matches subgoal 1:
   554       PG menu: Isabelle/Isar -> Show me -> matching rules
   555 The rules are ordered by how closely they match the subgoal.
   556 In particular, rules that solve a subgoal outright are displayed first
   557 (or rather last, the way they are printed).
   558 (ML: ProofGeneral.print_intros())
   559 
   560 * Pure: New flag trace_unify_fail causes unification to print
   561 diagnostic information (PG: in trace buffer) when it fails. This is
   562 useful for figuring out why single step proofs like rule, erule or
   563 assumption failed.
   564 
   565 * Pure: Locale specifications now produce predicate definitions
   566 according to the body of text (covering assumptions modulo local
   567 definitions); predicate "loc_axioms" covers newly introduced text,
   568 while "loc" is cumulative wrt. all included locale expressions; the
   569 latter view is presented only on export into the global theory
   570 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   571 on the old view without predicates;
   572 
   573 * Pure: predefined locales "var" and "struct" are useful for sharing
   574 parameters (as in CASL, for example); just specify something like
   575 ``var x + var y + struct M'' as import;
   576 
   577 * Pure: improved thms_containing: proper indexing of facts instead of
   578 raw theorems; check validity of results wrt. current name space;
   579 include local facts of proof configuration (also covers active
   580 locales), cover fixed variables in index; may use "_" in term
   581 specification; an optional limit for the number of printed facts may
   582 be given (the default is 40);
   583 
   584 * Pure: disallow duplicate fact bindings within new-style theory files
   585 (batch-mode only);
   586 
   587 * Provers: improved induct method: assumptions introduced by case
   588 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   589 the goal statement); "foo" still refers to all facts collectively;
   590 
   591 * Provers: the function blast.overloaded has been removed: all constants
   592 are regarded as potentially overloaded, which improves robustness in exchange
   593 for slight decrease in efficiency;
   594 
   595 * Provers/linorder: New generic prover for transitivity reasoning over
   596 linear orders.  Note: this prover is not efficient!
   597 
   598 * Isar: preview of problems to finish 'show' now produce an error
   599 rather than just a warning (in interactive mode);
   600 
   601 
   602 *** HOL ***
   603 
   604 * arith(_tac)
   605 
   606  - Produces a counter example if it cannot prove a goal.
   607    Note that the counter example may be spurious if the goal is not a formula
   608    of quantifier-free linear arithmetic.
   609    In ProofGeneral the counter example appears in the trace buffer.
   610 
   611  - Knows about div k and mod k where k is a numeral of type nat or int.
   612 
   613  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   614    linear arithmetic fails. This takes account of quantifiers and divisibility.
   615    Presburger arithmetic can also be called explicitly via presburger(_tac).
   616 
   617 * simp's arithmetic capabilities have been enhanced a bit: it now
   618 takes ~= in premises into account (by performing a case split);
   619 
   620 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   621 are distributed over a sum of terms;
   622 
   623 * New tactic "trans_tac" and method "trans" instantiate
   624 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   625 "<=", "<" and "=").
   626 
   627 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main
   628 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   629 
   630 * 'typedef' command has new option "open" to suppress the set
   631 definition;
   632 
   633 * functions Min and Max on finite sets have been introduced (theory
   634 Finite_Set);
   635 
   636 * attribute [symmetric] now works for relations as well; it turns
   637 (x,y) : R^-1 into (y,x) : R, and vice versa;
   638 
   639 * induct over a !!-quantified statement (say !!x1..xn):
   640   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   641 
   642 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   643 %x. None. Warning: empty_def now refers to the previously hidden definition
   644 of the empty set.
   645 
   646 * Algebra: formalization of classical algebra.  Intended as base for
   647 any algebraic development in Isabelle.  Currently covers group theory
   648 (up to Sylow's theorem) and ring theory (Universal Property of
   649 Univariate Polynomials).  Contributions welcome;
   650 
   651 * GroupTheory: deleted, since its material has been moved to Algebra;
   652 
   653 * Complex: new directory of the complex numbers with numeric constants,
   654 nonstandard complex numbers, and some complex analysis, standard and
   655 nonstandard (Jacques Fleuriot);
   656 
   657 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   658 
   659 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques
   660 Fleuriot);
   661 
   662 * Real/HahnBanach: updated and adapted to locales;
   663 
   664 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   665 Gray and Kramer);
   666 
   667 * UNITY: added the Meier-Sanders theory of progress sets;
   668 
   669 * MicroJava: bytecode verifier and lightweight bytecode verifier
   670 as abstract algorithms, instantiated to the JVM;
   671 
   672 * Bali: Java source language formalization. Type system, operational
   673 semantics, axiomatic semantics. Supported language features:
   674 classes, interfaces, objects,virtual methods, static methods,
   675 static/instance fields, arrays, access modifiers, definite
   676 assignment, exceptions.
   677 
   678 
   679 *** ZF ***
   680 
   681 * ZF/Constructible: consistency proof for AC (Gdel's constructible
   682 universe, etc.);
   683 
   684 * Main ZF: virtually all theories converted to new-style format;
   685 
   686 
   687 *** ML ***
   688 
   689 * Pure: Tactic.prove provides sane interface for internal proofs;
   690 omits the infamous "standard" operation, so this is more appropriate
   691 than prove_goalw_cterm in many situations (e.g. in simprocs);
   692 
   693 * Pure: improved error reporting of simprocs;
   694 
   695 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   696 up simprocs;
   697 
   698 
   699 *** Document preparation ***
   700 
   701 * uses \par instead of \\ for line breaks in theory text. This may
   702 shift some page breaks in large documents. To get the old behaviour
   703 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   704 
   705 * minimized dependencies of isabelle.sty and isabellesym.sty on
   706 other packages
   707 
   708 * \<euro> now needs package babel/greek instead of marvosym (which
   709 broke \Rightarrow)
   710 
   711 * normal size for \<zero>...\<nine> (uses \mathbf instead of
   712 textcomp package)
   713 
   714 
   715 
   716 New in Isabelle2002 (March 2002)
   717 --------------------------------
   718 
   719 *** Document preparation ***
   720 
   721 * greatly simplified document preparation setup, including more
   722 graceful interpretation of isatool usedir -i/-d/-D options, and more
   723 instructive isatool mkdir; users should basically be able to get
   724 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   725 users may run a separate document processing stage manually like this:
   726 "isatool usedir -D output HOL Test && isatool document Test/output";
   727 
   728 * theory dependency graph may now be incorporated into documents;
   729 isatool usedir -g true will produce session_graph.eps/.pdf for use
   730 with \includegraphics of LaTeX;
   731 
   732 * proper spacing of consecutive markup elements, especially text
   733 blocks after section headings;
   734 
   735 * support bold style (for single symbols only), input syntax is like
   736 this: "\<^bold>\<alpha>" or "\<^bold>A";
   737 
   738 * \<bullet> is now output as bold \cdot by default, which looks much
   739 better in printed text;
   740 
   741 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   742 note that these symbols are currently unavailable in Proof General /
   743 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   744 
   745 * isatool latex no longer depends on changed TEXINPUTS, instead
   746 isatool document copies the Isabelle style files to the target
   747 location;
   748 
   749 
   750 *** Isar ***
   751 
   752 * Pure/Provers: improved proof by cases and induction;
   753   - 'case' command admits impromptu naming of parameters (such as
   754     "case (Suc n)");
   755   - 'induct' method divinates rule instantiation from the inductive
   756     claim; no longer requires excessive ?P bindings for proper
   757     instantiation of cases;
   758   - 'induct' method properly enumerates all possibilities of set/type
   759     rules; as a consequence facts may be also passed through *type*
   760     rules without further ado;
   761   - 'induct' method now derives symbolic cases from the *rulified*
   762     rule (before it used to rulify cases stemming from the internal
   763     atomized version); this means that the context of a non-atomic
   764     statement becomes is included in the hypothesis, avoiding the
   765     slightly cumbersome show "PROP ?case" form;
   766   - 'induct' may now use elim-style induction rules without chaining
   767     facts, using ``missing'' premises from the goal state; this allows
   768     rules stemming from inductive sets to be applied in unstructured
   769     scripts, while still benefitting from proper handling of non-atomic
   770     statements; NB: major inductive premises need to be put first, all
   771     the rest of the goal is passed through the induction;
   772   - 'induct' proper support for mutual induction involving non-atomic
   773     rule statements (uses the new concept of simultaneous goals, see
   774     below);
   775   - append all possible rule selections, but only use the first
   776     success (no backtracking);
   777   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   778   - undeclared rule case names default to numbers 1, 2, 3, ...;
   779   - added 'print_induct_rules' (covered by help item in recent Proof
   780     General versions);
   781   - moved induct/cases attributes to Pure, methods to Provers;
   782   - generic method setup instantiated for FOL and HOL;
   783 
   784 * Pure: support multiple simultaneous goal statements, for example
   785 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   786 meta-level mechanism, this acts as if several individual goals had
   787 been stated separately; in particular common proof methods need to be
   788 repeated in order to cover all claims; note that a single elimination
   789 step is *not* sufficient to establish the two conjunctions, so this
   790 fails:
   791 
   792   assume "A & B" then have A and B ..   (*".." fails*)
   793 
   794 better use "obtain" in situations as above; alternative refer to
   795 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   796 
   797 * Pure: proper integration with ``locales''; unlike the original
   798 version by Florian Kammller, Isar locales package high-level proof
   799 contexts rather than raw logical ones (e.g. we admit to include
   800 attributes everywhere); operations on locales include merge and
   801 rename; support for implicit arguments (``structures''); simultaneous
   802 type-inference over imports and text; see also HOL/ex/Locales.thy for
   803 some examples;
   804 
   805 * Pure: the following commands have been ``localized'', supporting a
   806 target locale specification "(in name)": 'lemma', 'theorem',
   807 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   808 stored both within the locale and at the theory level (exported and
   809 qualified by the locale name);
   810 
   811 * Pure: theory goals may now be specified in ``long'' form, with
   812 ad-hoc contexts consisting of arbitrary locale elements. for example
   813 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   814 definitions may be given, too); the result is a meta-level rule with
   815 the context elements being discharged in the obvious way;
   816 
   817 * Pure: new proof command 'using' allows to augment currently used
   818 facts after a goal statement ('using' is syntactically analogous to
   819 'apply', but acts on the goal's facts only); this allows chained facts
   820 to be separated into parts given before and after a claim, as in
   821 ``from a and b have C using d and e <proof>'';
   822 
   823 * Pure: renamed "antecedent" case to "rule_context";
   824 
   825 * Pure: new 'judgment' command records explicit information about the
   826 object-logic embedding (used by several tools internally); no longer
   827 use hard-wired "Trueprop";
   828 
   829 * Pure: added 'corollary' command;
   830 
   831 * Pure: fixed 'token_translation' command;
   832 
   833 * Pure: removed obsolete 'exported' attribute;
   834 
   835 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   836 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   837 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   838 
   839 * Pure: method 'atomize' presents local goal premises as object-level
   840 statements (atomic meta-level propositions); setup controlled via
   841 rewrite rules declarations of 'atomize' attribute; example
   842 application: 'induct' method with proper rule statements in improper
   843 proof *scripts*;
   844 
   845 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   846 now consider the syntactic context of assumptions, giving a better
   847 chance to get type-inference of the arguments right (this is
   848 especially important for locales);
   849 
   850 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   851 mode;
   852 
   853 * Pure/obtain: the formal conclusion "thesis", being marked as
   854 ``internal'', may no longer be reference directly in the text;
   855 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   856 situations;
   857 
   858 * Pure: generic 'sym' attribute which declares a rule both as pure
   859 'elim?' and for the 'symmetric' operation;
   860 
   861 * Pure: marginal comments ``--'' may now occur just anywhere in the
   862 text; the fixed correlation with particular command syntax has been
   863 discontinued;
   864 
   865 * Pure: new method 'rules' is particularly well-suited for proof
   866 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   867 but often produces more compact proof terms with less detours;
   868 
   869 * Pure/Provers/classical: simplified integration with pure rule
   870 attributes and methods; the classical "intro?/elim?/dest?"
   871 declarations coincide with the pure ones; the "rule" method no longer
   872 includes classically swapped intros; "intro" and "elim" methods no
   873 longer pick rules from the context; also got rid of ML declarations
   874 AddXIs/AddXEs/AddXDs; all of this has some potential for
   875 INCOMPATIBILITY;
   876 
   877 * Provers/classical: attribute 'swapped' produces classical inversions
   878 of introduction rules;
   879 
   880 * Provers/simplifier: 'simplified' attribute may refer to explicit
   881 rules instead of full simplifier context; 'iff' attribute handles
   882 conditional rules;
   883 
   884 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   885 
   886 * HOL: 'recdef' now fails on unfinished automated proofs, use
   887 "(permissive)" option to recover old behavior;
   888 
   889 * HOL: 'inductive' no longer features separate (collective) attributes
   890 for 'intros' (was found too confusing);
   891 
   892 * HOL: properly declared induction rules less_induct and
   893 wf_induct_rule;
   894 
   895 
   896 *** HOL ***
   897 
   898 * HOL: moved over to sane numeral syntax; the new policy is as
   899 follows:
   900 
   901   - 0 and 1 are polymorphic constants, which are defined on any
   902   numeric type (nat, int, real etc.);
   903 
   904   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   905   binary representation internally;
   906 
   907   - type nat has special constructor Suc, and generally prefers Suc 0
   908   over 1::nat and Suc (Suc 0) over 2::nat;
   909 
   910 This change may cause significant problems of INCOMPATIBILITY; here
   911 are some hints on converting existing sources:
   912 
   913   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   914   entities, so expressions involving "-" (unary or binary minus) need
   915   to be spaced properly;
   916 
   917   - existing occurrences of "1" may need to be constraint "1::nat" or
   918   even replaced by Suc 0; similar for old "2";
   919 
   920   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   921 
   922   - remove all special provisions on numerals in proofs;
   923 
   924 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   925 representation (depends on bin_arith_simps in the default context);
   926 
   927 * HOL: symbolic syntax for x^2 (numeral 2);
   928 
   929 * HOL: the class of all HOL types is now called "type" rather than
   930 "term"; INCOMPATIBILITY, need to adapt references to this type class
   931 in axclass/classes, instance/arities, and (usually rare) occurrences
   932 in typings (of consts etc.); internally the class is called
   933 "HOL.type", ML programs should refer to HOLogic.typeS;
   934 
   935 * HOL/record package improvements:
   936   - new derived operations "fields" to build a partial record section,
   937     "extend" to promote a fixed record to a record scheme, and
   938     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   939     declared as simp by default;
   940   - shared operations ("more", "fields", etc.) now need to be always
   941     qualified) --- potential INCOMPATIBILITY;
   942   - removed "make_scheme" operations (use "make" with "extend") --
   943     INCOMPATIBILITY;
   944   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   945   - provides cases/induct rules for use with corresponding Isar
   946     methods (for concrete records, record schemes, concrete more
   947     parts, and schematic more parts -- in that order);
   948   - internal definitions directly based on a light-weight abstract
   949     theory of product types over typedef rather than datatype;
   950 
   951 * HOL: generic code generator for generating executable ML code from
   952 specifications; specific support for HOL constructs such as inductive
   953 datatypes and sets, as well as recursive functions; can be invoked
   954 via 'generate_code' theory section;
   955 
   956 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   957 
   958 * HOL: consolidated and renamed several theories.  In particular:
   959         Ord.thy has been absorbed into HOL.thy
   960         String.thy has been absorbed into List.thy
   961 
   962 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   963 (beware of argument permutation!);
   964 
   965 * HOL: linorder_less_split superseded by linorder_cases;
   966 
   967 * HOL/List: "nodups" renamed to "distinct";
   968 
   969 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   970 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   971   - Ex_def has changed, now need to use some_eq_ex
   972 
   973 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   974 in this (rare) case use:
   975 
   976   delSWrapper "split_all_tac"
   977   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   978 
   979 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   980 MAY FAIL;
   981 
   982 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   983 Isabelle's type classes, ^ on functions and relations has too general
   984 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   985 necessary to attach explicit type constraints;
   986 
   987 * HOL/Relation: the prefix name of the infix "O" has been changed from
   988 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   989 renamed accordingly (eg "compI" -> "rel_compI").
   990 
   991 * HOL: syntax translations now work properly with numerals and records
   992 expressions;
   993 
   994 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   995 of "lam" -- INCOMPATIBILITY;
   996 
   997 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   998 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   999 renamed "Product_Type.unit";
  1000 
  1001 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
  1002 
  1003 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
  1004 the "cases" method);
  1005 
  1006 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
  1007 Florian Kammller);
  1008 
  1009 * HOL/IMP: updated and converted to new-style theory format; several
  1010 parts turned into readable document, with proper Isar proof texts and
  1011 some explanations (by Gerwin Klein);
  1012 
  1013 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
  1014 
  1015 * HOL-Hyperreal is now a logic image;
  1016 
  1017 
  1018 *** HOLCF ***
  1019 
  1020 * Isar: consts/constdefs supports mixfix syntax for continuous
  1021 operations;
  1022 
  1023 * Isar: domain package adapted to new-style theory format, e.g. see
  1024 HOLCF/ex/Dnat.thy;
  1025 
  1026 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
  1027 potential INCOMPATIBILITY; now use plain induct_tac instead of former
  1028 lift.induct_tac, always use UU instead of Undef;
  1029 
  1030 * HOLCF/IMP: updated and converted to new-style theory;
  1031 
  1032 
  1033 *** ZF ***
  1034 
  1035 * Isar: proper integration of logic-specific tools and packages,
  1036 including theory commands '(co)inductive', '(co)datatype',
  1037 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
  1038 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
  1039 
  1040 * theory Main no longer includes AC; for the Axiom of Choice, base
  1041 your theory on Main_ZFC;
  1042 
  1043 * the integer library now covers quotients and remainders, with many
  1044 laws relating division to addition, multiplication, etc.;
  1045 
  1046 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
  1047 typeless version of the formalism;
  1048 
  1049 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
  1050 format;
  1051 
  1052 * ZF/Induct: new directory for examples of inductive definitions,
  1053 including theory Multiset for multiset orderings; converted to
  1054 new-style theory format;
  1055 
  1056 * ZF: many new theorems about lists, ordinals, etc.;
  1057 
  1058 
  1059 *** General ***
  1060 
  1061 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
  1062 variable proof controls level of detail: 0 = no proofs (only oracle
  1063 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
  1064 also ref manual for further ML interfaces;
  1065 
  1066 * Pure/axclass: removed obsolete ML interface
  1067 goal_subclass/goal_arity;
  1068 
  1069 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
  1070 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
  1071 separate tokens, so expressions involving minus need to be spaced
  1072 properly;
  1073 
  1074 * Pure/syntax: support non-oriented infixes, using keyword "infix"
  1075 rather than "infixl" or "infixr";
  1076 
  1077 * Pure/syntax: concrete syntax for dummy type variables admits genuine
  1078 sort constraint specifications in type inference; e.g. "x::_::foo"
  1079 ensures that the type of "x" is of sort "foo" (but not necessarily a
  1080 type variable);
  1081 
  1082 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
  1083 control output of nested => (types); the default behavior is
  1084 "type_brackets";
  1085 
  1086 * Pure/syntax: builtin parse translation for "_constify" turns valued
  1087 tokens into AST constants;
  1088 
  1089 * Pure/syntax: prefer later declarations of translations and print
  1090 translation functions; potential INCOMPATIBILITY: need to reverse
  1091 multiple declarations for same syntax element constant;
  1092 
  1093 * Pure/show_hyps reset by default (in accordance to existing Isar
  1094 practice);
  1095 
  1096 * Provers/classical: renamed addaltern to addafter, addSaltern to
  1097 addSafter;
  1098 
  1099 * Provers/clasimp: ``iff'' declarations now handle conditional rules
  1100 as well;
  1101 
  1102 * system: tested support for MacOS X; should be able to get Isabelle +
  1103 Proof General to work in a plain Terminal after installing Poly/ML
  1104 (e.g. from the Isabelle distribution area) and GNU bash alone
  1105 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
  1106 support requires further installations, e.g. from
  1107 http://fink.sourceforge.net/);
  1108 
  1109 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
  1110 
  1111 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
  1112 of 40 MB), cf. ML_OPTIONS;
  1113 
  1114 * system: Proof General keywords specification is now part of the
  1115 Isabelle distribution (see etc/isar-keywords.el);
  1116 
  1117 * system: support for persistent Proof General sessions (refrain from
  1118 outdating all loaded theories on startup); user may create writable
  1119 logic images like this: ``isabelle -q HOL Test'';
  1120 
  1121 * system: smart selection of Isabelle process versus Isabelle
  1122 interface, accommodates case-insensitive file systems (e.g. HFS+); may
  1123 run both "isabelle" and "Isabelle" even if file names are badly
  1124 damaged (executable inspects the case of the first letter of its own
  1125 name); added separate "isabelle-process" and "isabelle-interface";
  1126 
  1127 * system: refrain from any attempt at filtering input streams; no
  1128 longer support ``8bit'' encoding of old isabelle font, instead proper
  1129 iso-latin characters may now be used; the related isatools
  1130 "symbolinput" and "nonascii" have disappeared as well;
  1131 
  1132 * system: removed old "xterm" interface (the print modes "xterm" and
  1133 "xterm_color" are still available for direct use in a suitable
  1134 terminal);
  1135 
  1136 
  1137 
  1138 New in Isabelle99-2 (February 2001)
  1139 -----------------------------------
  1140 
  1141 *** Overview of INCOMPATIBILITIES ***
  1142 
  1143 * HOL: please note that theories in the Library and elsewhere often use the
  1144 new-style (Isar) format; to refer to their theorems in an ML script you must
  1145 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
  1146 
  1147 * HOL: inductive package no longer splits induction rule aggressively,
  1148 but only as far as specified by the introductions given; the old
  1149 format may be recovered via ML function complete_split_rule or attribute
  1150 'split_rule (complete)';
  1151 
  1152 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
  1153 gfp_Tarski to gfp_unfold;
  1154 
  1155 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
  1156 
  1157 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
  1158 relation); infix "^^" has been renamed "``"; infix "``" has been
  1159 renamed "`"; "univalent" has been renamed "single_valued";
  1160 
  1161 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
  1162 operation;
  1163 
  1164 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
  1165 
  1166 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
  1167 
  1168 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
  1169 consequence, it is no longer monotonic wrt. the local goal context
  1170 (which is now passed through the inductive cases);
  1171 
  1172 * Document preparation: renamed standard symbols \<ll> to \<lless> and
  1173 \<gg> to \<ggreater>;
  1174 
  1175 
  1176 *** Document preparation ***
  1177 
  1178 * \isabellestyle{NAME} selects version of Isabelle output (currently
  1179 available: are "it" for near math-mode best-style output, "sl" for
  1180 slanted text style, and "tt" for plain type-writer; if no
  1181 \isabellestyle command is given, output is according to slanted
  1182 type-writer);
  1183 
  1184 * support sub/super scripts (for single symbols only), input syntax is
  1185 like this: "A\<^sup>*" or "A\<^sup>\<star>";
  1186 
  1187 * some more standard symbols; see Appendix A of the system manual for
  1188 the complete list of symbols defined in isabellesym.sty;
  1189 
  1190 * improved isabelle style files; more abstract symbol implementation
  1191 (should now use \isamath{...} and \isatext{...} in custom symbol
  1192 definitions);
  1193 
  1194 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
  1195 state; Note that presentation of goal states does not conform to
  1196 actual human-readable proof documents.  Please do not include goal
  1197 states into document output unless you really know what you are doing!
  1198 
  1199 * proper indentation of antiquoted output with proportional LaTeX
  1200 fonts;
  1201 
  1202 * no_document ML operator temporarily disables LaTeX document
  1203 generation;
  1204 
  1205 * isatool unsymbolize tunes sources for plain ASCII communication;
  1206 
  1207 
  1208 *** Isar ***
  1209 
  1210 * Pure: Isar now suffers initial goal statements to contain unbound
  1211 schematic variables (this does not conform to actual readable proof
  1212 documents, due to unpredictable outcome and non-compositional proof
  1213 checking); users who know what they are doing may use schematic goals
  1214 for Prolog-style synthesis of proven results;
  1215 
  1216 * Pure: assumption method (an implicit finishing) now handles actual
  1217 rules as well;
  1218 
  1219 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
  1220 initial goal, declare "that" only as Pure intro (only for single
  1221 steps); the "that" rule assumption may now be involved in implicit
  1222 finishing, thus ".." becomes a feasible for trivial obtains;
  1223 
  1224 * Pure: default proof step now includes 'intro_classes'; thus trivial
  1225 instance proofs may be performed by "..";
  1226 
  1227 * Pure: ?thesis / ?this / "..." now work for pure meta-level
  1228 statements as well;
  1229 
  1230 * Pure: more robust selection of calculational rules;
  1231 
  1232 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
  1233 rule (as well as the assumption rule);
  1234 
  1235 * Pure: 'thm_deps' command visualizes dependencies of theorems and
  1236 lemmas, using the graph browser tool;
  1237 
  1238 * Pure: predict failure of "show" in interactive mode;
  1239 
  1240 * Pure: 'thms_containing' now takes actual terms as arguments;
  1241 
  1242 * HOL: improved method 'induct' --- now handles non-atomic goals
  1243 (potential INCOMPATIBILITY); tuned error handling;
  1244 
  1245 * HOL: cases and induct rules now provide explicit hints about the
  1246 number of facts to be consumed (0 for "type" and 1 for "set" rules);
  1247 any remaining facts are inserted into the goal verbatim;
  1248 
  1249 * HOL: local contexts (aka cases) may now contain term bindings as
  1250 well; the 'cases' and 'induct' methods new provide a ?case binding for
  1251 the result to be shown in each case;
  1252 
  1253 * HOL: added 'recdef_tc' command;
  1254 
  1255 * isatool convert assists in eliminating legacy ML scripts;
  1256 
  1257 
  1258 *** HOL ***
  1259 
  1260 * HOL/Library: a collection of generic theories to be used together
  1261 with main HOL; the theory loader path already includes this directory
  1262 by default; the following existing theories have been moved here:
  1263 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
  1264 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
  1265 
  1266 * HOL/Unix: "Some aspects of Unix file-system security", a typical
  1267 modelling and verification task performed in Isabelle/HOL +
  1268 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
  1269 
  1270 * HOL/Algebra: special summation operator SUM no longer exists, it has
  1271 been replaced by setsum; infix 'assoc' now has priority 50 (like
  1272 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
  1273 'domain', this makes the theory consistent with mathematical
  1274 literature;
  1275 
  1276 * HOL basics: added overloaded operations "inverse" and "divide"
  1277 (infix "/"), syntax for generic "abs" operation, generic summation
  1278 operator \<Sum>;
  1279 
  1280 * HOL/typedef: simplified package, provide more useful rules (see also
  1281 HOL/subset.thy);
  1282 
  1283 * HOL/datatype: induction rule for arbitrarily branching datatypes is
  1284 now expressed as a proper nested rule (old-style tactic scripts may
  1285 require atomize_strip_tac to cope with non-atomic premises);
  1286 
  1287 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
  1288 to "split_conv" (old name still available for compatibility);
  1289 
  1290 * HOL: improved concrete syntax for strings (e.g. allows translation
  1291 rules with string literals);
  1292 
  1293 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
  1294  and Fleuriot's mechanization of analysis, including the transcendental
  1295  functions for the reals;
  1296 
  1297 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
  1298 
  1299 
  1300 *** CTT ***
  1301 
  1302 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
  1303 "lam" is displayed as TWO lambda-symbols
  1304 
  1305 * CTT: theory Main now available, containing everything (that is, Bool
  1306 and Arith);
  1307 
  1308 
  1309 *** General ***
  1310 
  1311 * Pure: the Simplifier has been implemented properly as a derived rule
  1312 outside of the actual kernel (at last!); the overall performance
  1313 penalty in practical applications is about 50%, while reliability of
  1314 the Isabelle inference kernel has been greatly improved;
  1315 
  1316 * print modes "brackets" and "no_brackets" control output of nested =>
  1317 (types) and ==> (props); the default behaviour is "brackets";
  1318 
  1319 * Provers: fast_tac (and friends) now handle actual object-logic rules
  1320 as assumptions as well;
  1321 
  1322 * system: support Poly/ML 4.0;
  1323 
  1324 * system: isatool install handles KDE version 1 or 2;
  1325 
  1326 
  1327 
  1328 New in Isabelle99-1 (October 2000)
  1329 ----------------------------------
  1330 
  1331 *** Overview of INCOMPATIBILITIES ***
  1332 
  1333 * HOL: simplification of natural numbers is much changed; to partly
  1334 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
  1335 issue the following ML commands:
  1336 
  1337   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
  1338   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
  1339 
  1340 * HOL: simplification no longer dives into case-expressions; this is
  1341 controlled by "t.weak_case_cong" for each datatype t;
  1342 
  1343 * HOL: nat_less_induct renamed to less_induct;
  1344 
  1345 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
  1346 fixsome to patch .thy and .ML sources automatically;
  1347 
  1348   select_equality  -> some_equality
  1349   select_eq_Ex     -> some_eq_ex
  1350   selectI2EX       -> someI2_ex
  1351   selectI2         -> someI2
  1352   selectI          -> someI
  1353   select1_equality -> some1_equality
  1354   Eps_sym_eq       -> some_sym_eq_trivial
  1355   Eps_eq           -> some_eq_trivial
  1356 
  1357 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
  1358 
  1359 * HOL: removed obsolete theorem binding expand_if (refer to split_if
  1360 instead);
  1361 
  1362 * HOL: the recursion equations generated by 'recdef' are now called
  1363 f.simps instead of f.rules;
  1364 
  1365 * HOL: qed_spec_mp now also handles bounded ALL as well;
  1366 
  1367 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  1368 sometimes be needed;
  1369 
  1370 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  1371 
  1372 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  1373 
  1374 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  1375 product is now "<*>" instead of "Times"; the lexicographic product is
  1376 now "<*lex*>" instead of "**";
  1377 
  1378 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  1379 of main HOL, but was unused); better use HOL's datatype package;
  1380 
  1381 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  1382 the old syntax may be recovered as follows:
  1383 
  1384   syntax (symbols)
  1385     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  1386       (infixl "\\<oplus>" 100)
  1387 
  1388 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1389 
  1390 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1391 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1392 internally;
  1393 
  1394 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1395 changed from A/r to A//r;
  1396 
  1397 * ZF: new treatment of arithmetic (nat & int) may break some old
  1398 proofs;
  1399 
  1400 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1401 rulify -> rule_format, elimify -> elim_format, ...);
  1402 
  1403 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1404 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1405 should have to change intro!! to intro? only); replaced "delrule" by
  1406 "rule del";
  1407 
  1408 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1409 
  1410 * Provers: strengthened force_tac by using new first_best_tac;
  1411 
  1412 * LaTeX document preparation: several changes of isabelle.sty (see
  1413 lib/texinputs);
  1414 
  1415 
  1416 *** Document preparation ***
  1417 
  1418 * formal comments (text blocks etc.) in new-style theories may now
  1419 contain antiquotations of thm/prop/term/typ/text to be presented
  1420 according to latex print mode; concrete syntax is like this:
  1421 @{term[show_types] "f(x) = a + x"};
  1422 
  1423 * isatool mkdir provides easy setup of Isabelle session directories,
  1424 including proper document sources;
  1425 
  1426 * generated LaTeX sources are now deleted after successful run
  1427 (isatool document -c); may retain a copy somewhere else via -D option
  1428 of isatool usedir;
  1429 
  1430 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1431 style files, achieving self-contained LaTeX sources and simplifying
  1432 LaTeX debugging;
  1433 
  1434 * old-style theories now produce (crude) LaTeX output as well;
  1435 
  1436 * browser info session directories are now self-contained (may be put
  1437 on WWW server seperately); improved graphs of nested sessions; removed
  1438 graph for 'all sessions';
  1439 
  1440 * several improvements in isabelle style files; \isabellestyle{it}
  1441 produces fake math mode output; \isamarkupheader is now \section by
  1442 default; see lib/texinputs/isabelle.sty etc.;
  1443 
  1444 
  1445 *** Isar ***
  1446 
  1447 * Isar/Pure: local results and corresponding term bindings are now
  1448 subject to Hindley-Milner polymorphism (similar to ML); this
  1449 accommodates incremental type-inference very nicely;
  1450 
  1451 * Isar/Pure: new derived language element 'obtain' supports
  1452 generalized existence reasoning;
  1453 
  1454 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1455 support accumulation of results, without applying any rules yet;
  1456 useful to collect intermediate results without explicit name
  1457 references, and for use with transitivity rules with more than 2
  1458 premises;
  1459 
  1460 * Isar/Pure: scalable support for case-analysis type proofs: new
  1461 'case' language element refers to local contexts symbolically, as
  1462 produced by certain proof methods; internally, case names are attached
  1463 to theorems as "tags";
  1464 
  1465 * Isar/Pure: theory command 'hide' removes declarations from
  1466 class/type/const name spaces;
  1467 
  1468 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1469 indicate potential overloading;
  1470 
  1471 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1472 
  1473 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1474 "{a,b,c}" instead of {a,b,c};
  1475 
  1476 * Isar/Pure now provides its own version of intro/elim/dest
  1477 attributes; useful for building new logics, but beware of confusion
  1478 with the version in Provers/classical;
  1479 
  1480 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1481 case name 'antecedent';
  1482 
  1483 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1484 to the current context is now done automatically);
  1485 
  1486 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1487 for definining proof methods in ML;
  1488 
  1489 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1490 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1491 most cases, one should have to change intro!! to intro? only);
  1492 replaced "delrule" by "rule del";
  1493 
  1494 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1495 'symmetric' attribute (the latter supercedes [RS sym]);
  1496 
  1497 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1498 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1499 well (including splits);
  1500 
  1501 * Isar/Provers: Simplifier and Classical methods now support all kind
  1502 of modifiers used in the past, including 'cong', 'iff', etc.
  1503 
  1504 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1505 of Simplifier and Classical reasoner);
  1506 
  1507 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1508 now support named cases; major packages (inductive, datatype, primrec,
  1509 recdef) support case names and properly name parameters;
  1510 
  1511 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1512 monotonicity conditions are extracted to be proven at end of
  1513 calculations;
  1514 
  1515 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1516 method anyway;
  1517 
  1518 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1519 split_if split_if_asm; datatype package provides theorems foo.splits =
  1520 foo.split foo.split_asm for each datatype;
  1521 
  1522 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1523 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1524 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1525 use "(cases (simplified))" method in proper proof texts);
  1526 
  1527 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1528 
  1529 * Isar: names of theorems etc. may be natural numbers as well;
  1530 
  1531 * Isar: 'pr' command: optional arguments for goals_limit and
  1532 ProofContext.prems_limit; no longer prints theory contexts, but only
  1533 proof states;
  1534 
  1535 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1536 additional print modes to be specified; e.g. "pr(latex)" will print
  1537 proof state according to the Isabelle LaTeX style;
  1538 
  1539 * Isar: improved support for emulating tactic scripts, including proof
  1540 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1541 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1542 (for HOL datatypes);
  1543 
  1544 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1545 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1546 'proof method scripts' have to be in depth-first order;
  1547 
  1548 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1549 
  1550 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1551 should instead use individual commands for printing items
  1552 (print_commands, print_methods etc.);
  1553 
  1554 * Isar: added 'nothing' --- the empty list of theorems;
  1555 
  1556 
  1557 *** HOL ***
  1558 
  1559 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1560 corresponding virtual machine and a specification of its bytecode
  1561 verifier and a lightweight bytecode verifier, including proofs of
  1562 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1563 Cornelia Pusch (see also the homepage of project Bali at
  1564 http://isabelle.in.tum.de/Bali/);
  1565 
  1566 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1567 Clemens Ballarin;
  1568 
  1569 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1570 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1571 Rasmussen;
  1572 
  1573 * HOL/Lattice: fundamental concepts of lattice theory and order
  1574 structures, including duals, properties of bounds versus algebraic
  1575 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1576 Theorem for complete lattices etc.; may also serve as a demonstration
  1577 for abstract algebraic reasoning using axiomatic type classes, and
  1578 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1579 
  1580 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1581 von Oheimb;
  1582 
  1583 * HOL/IMPP: extension of IMP with local variables and mutually
  1584 recursive procedures, by David von Oheimb;
  1585 
  1586 * HOL/Lambda: converted into new-style theory and document;
  1587 
  1588 * HOL/ex/Multiquote: example of multiple nested quotations and
  1589 anti-quotations -- basically a generalized version of de-Bruijn
  1590 representation; very useful in avoiding lifting of operations;
  1591 
  1592 * HOL/record: added general record equality rule to simpset; fixed
  1593 select-update simplification procedure to handle extended records as
  1594 well; admit "r" as field name;
  1595 
  1596 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1597 other numeric types and also as the identity of groups, rings, etc.;
  1598 
  1599 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1600 Types nat and int belong to this axclass;
  1601 
  1602 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1603    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1604    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1605   two terms #m*u and #n*u are replaced by #(m+n)*u
  1606     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1607   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1608     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1609 
  1610 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1611 powerful prover for predicate logic but knows nothing of clasets; see
  1612 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1613 
  1614 * HOL: new version of "case_tac" subsumes both boolean case split and
  1615 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1616 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1617 
  1618 * HOL: simplification no longer dives into case-expressions: only the
  1619 selector expression is simplified, but not the remaining arms; to
  1620 enable full simplification of case-expressions for datatype t, you may
  1621 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1622 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1623 
  1624 * HOL/recdef: the recursion equations generated by 'recdef' for
  1625 function 'f' are now called f.simps instead of f.rules; if all
  1626 termination conditions are proved automatically, these simplification
  1627 rules are added to the simpset, as in primrec; rules may be named
  1628 individually as well, resulting in a separate list of theorems for
  1629 each equation;
  1630 
  1631 * HOL/While is a new theory that provides a while-combinator. It
  1632 permits the definition of tail-recursive functions without the
  1633 provision of a termination measure. The latter is necessary once the
  1634 invariant proof rule for while is applied.
  1635 
  1636 * HOL: new (overloaded) notation for the set of elements below/above
  1637 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1638 
  1639 * HOL: theorems impI, allI, ballI bound as "strip";
  1640 
  1641 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1642 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1643 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1644 
  1645 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1646 
  1647 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1648 main HOL, but was unused);
  1649 
  1650 * HOL: fewer consts declared as global (e.g. have to refer to
  1651 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1652 
  1653 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1654 in case of overlap with user translations (e.g. judgements over
  1655 tuples); (note that the underlying logical represenation is still
  1656 bogus);
  1657 
  1658 
  1659 *** ZF ***
  1660 
  1661 * ZF: simplification automatically cancels common terms in arithmetic
  1662 expressions over nat and int;
  1663 
  1664 * ZF: new treatment of nat to minimize type-checking: all operators
  1665 coerce their operands to a natural number using the function natify,
  1666 making the algebraic laws unconditional;
  1667 
  1668 * ZF: as above, for int: operators coerce their operands to an integer
  1669 using the function intify;
  1670 
  1671 * ZF: the integer library now contains many of the usual laws for the
  1672 orderings, including $<=, and monotonicity laws for $+ and $*;
  1673 
  1674 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1675 simplification;
  1676 
  1677 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1678 to the simplifier and classical reasoner simultaneously;
  1679 
  1680 
  1681 *** General ***
  1682 
  1683 * Provers: blast_tac now handles actual object-logic rules as
  1684 assumptions; note that auto_tac uses blast_tac internally as well;
  1685 
  1686 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1687 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1688 
  1689 * Provers: delrules now handles destruct rules as well (no longer need
  1690 explicit make_elim);
  1691 
  1692 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1693   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1694 use instead the strong form,
  1695   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1696 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1697 from destruct-rules;
  1698 
  1699 * Provers: Simplifier.easy_setup provides a fast path to basic
  1700 Simplifier setup for new object-logics;
  1701 
  1702 * Pure: AST translation rules no longer require constant head on LHS;
  1703 
  1704 * Pure: improved name spaces: ambiguous output is qualified; support
  1705 for hiding of names;
  1706 
  1707 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1708 XSYMBOL_HOME; no longer need to do manual configuration in most
  1709 situations;
  1710 
  1711 * system: compression of ML heaps images may now be controlled via -c
  1712 option of isabelle and isatool usedir (currently only observed by
  1713 Poly/ML);
  1714 
  1715 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1716 useful for remote X11);
  1717 
  1718 * system: provide TAGS file for Isabelle sources;
  1719 
  1720 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1721 order;
  1722 
  1723 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1724 timing flag supersedes proof_timing and Toplevel.trace;
  1725 
  1726 * ML: new combinators |>> and |>>> for incremental transformations
  1727 with secondary results (e.g. certain theory extensions):
  1728 
  1729 * ML: PureThy.add_defs gets additional argument to indicate potential
  1730 overloading (usually false);
  1731 
  1732 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1733 results;
  1734 
  1735 
  1736 
  1737 New in Isabelle99 (October 1999)
  1738 --------------------------------
  1739 
  1740 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1741 
  1742 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1743 are no longer simplified.  (This allows the simplifier to unfold recursive
  1744 functional programs.)  To restore the old behaviour, declare
  1745 
  1746     Delcongs [if_weak_cong];
  1747 
  1748 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1749 complement;
  1750 
  1751 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1752 
  1753 * HOL/datatype: mutual_induct_tac no longer exists --
  1754   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1755 
  1756 * HOL/typedef: fixed type inference for representing set; type
  1757 arguments now have to occur explicitly on the rhs as type constraints;
  1758 
  1759 * ZF: The con_defs part of an inductive definition may no longer refer
  1760 to constants declared in the same theory;
  1761 
  1762 * HOL, ZF: the function mk_cases, generated by the inductive
  1763 definition package, has lost an argument.  To simplify its result, it
  1764 uses the default simpset instead of a supplied list of theorems.
  1765 
  1766 * HOL/List: the constructors of type list are now Nil and Cons;
  1767 
  1768 * Simplifier: the type of the infix ML functions
  1769         setSSolver addSSolver setSolver addSolver
  1770 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1771 for packaging solvers. A solver is created via
  1772         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1773 where the string argument is only a comment.
  1774 
  1775 
  1776 *** Proof tools ***
  1777 
  1778 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1779 decision procedure for linear arithmetic. Currently it is used for
  1780 types `nat', `int', and `real' in HOL (see below); it can, should and
  1781 will be instantiated for other types and logics as well.
  1782 
  1783 * The simplifier now accepts rewrite rules with flexible heads, eg
  1784      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1785   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1786   matching.
  1787 
  1788 
  1789 *** General ***
  1790 
  1791 * New Isabelle/Isar subsystem provides an alternative to traditional
  1792 tactical theorem proving; together with the ProofGeneral/isar user
  1793 interface it offers an interactive environment for developing human
  1794 readable proof documents (Isar == Intelligible semi-automated
  1795 reasoning); for further information see isatool doc isar-ref,
  1796 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1797 
  1798 * improved and simplified presentation of theories: better HTML markup
  1799 (including colors), graph views in several sizes; isatool usedir now
  1800 provides a proper interface for user theories (via -P option); actual
  1801 document preparation based on (PDF)LaTeX is available as well (for
  1802 new-style theories only); see isatool doc system for more information;
  1803 
  1804 * native support for Proof General, both for classic Isabelle and
  1805 Isabelle/Isar;
  1806 
  1807 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1808 using the graph browser tool;
  1809 
  1810 * Isabelle manuals now also available as PDF;
  1811 
  1812 * theory loader rewritten from scratch (may not be fully
  1813 bug-compatible); old loadpath variable has been replaced by show_path,
  1814 add_path, del_path, reset_path functions; new operations such as
  1815 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1816 isatool doc ref);
  1817 
  1818 * improved isatool install: option -k creates KDE application icon,
  1819 option -p DIR installs standalone binaries;
  1820 
  1821 * added ML_PLATFORM setting (useful for cross-platform installations);
  1822 more robust handling of platform specific ML images for SML/NJ;
  1823 
  1824 * the settings environment is now statically scoped, i.e. it is never
  1825 created again in sub-processes invoked from isabelle, isatool, or
  1826 Isabelle;
  1827 
  1828 * path element specification '~~' refers to '$ISABELLE_HOME';
  1829 
  1830 * in locales, the "assumes" and "defines" parts may be omitted if
  1831 empty;
  1832 
  1833 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1834 long arrows);
  1835 
  1836 * new print_mode "HTML";
  1837 
  1838 * new flag show_tags controls display of tags of theorems (which are
  1839 basically just comments that may be attached by some tools);
  1840 
  1841 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1842 mode and goal output format:
  1843 
  1844 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1845 244c244
  1846 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1847 ---
  1848 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1849 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1850 181c181
  1851 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1852 ---
  1853 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1854 
  1855 * function bind_thms stores lists of theorems (cf. bind_thm);
  1856 
  1857 * new shorthand tactics ftac, eatac, datac, fatac;
  1858 
  1859 * qed (and friends) now accept "" as result name; in that case the
  1860 theorem is not stored, but proper checks and presentation of the
  1861 result still apply;
  1862 
  1863 * theorem database now also indexes constants "Trueprop", "all",
  1864 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1865 
  1866 
  1867 *** HOL ***
  1868 
  1869 ** HOL arithmetic **
  1870 
  1871 * There are now decision procedures for linear arithmetic over nat and
  1872 int:
  1873 
  1874 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1875 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1876 are treated as atomic; subformulae not involving type `nat' or `int'
  1877 are ignored; quantified subformulae are ignored unless they are
  1878 positive universal or negative existential. The tactic has to be
  1879 invoked by hand and can be a little bit slow. In particular, the
  1880 running time is exponential in the number of occurrences of `min' and
  1881 `max', and `-' on `nat'.
  1882 
  1883 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1884 (negated) (in)equalities among the premises and the conclusion into
  1885 account (i.e. no compound formulae) and does not know about `min' and
  1886 `max', and `-' on `nat'. It is fast and is used automatically by the
  1887 simplifier.
  1888 
  1889 NB: At the moment, these decision procedures do not cope with mixed
  1890 nat/int formulae where the two parts interact, such as `m < n ==>
  1891 int(m) < int(n)'.
  1892 
  1893 * HOL/Numeral provides a generic theory of numerals (encoded
  1894 efficiently as bit strings); setup for types nat/int/real is in place;
  1895 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1896 int, existing theories and proof scripts may require a few additional
  1897 type constraints;
  1898 
  1899 * integer division and remainder can now be performed on constant
  1900 arguments;
  1901 
  1902 * many properties of integer multiplication, division and remainder
  1903 are now available;
  1904 
  1905 * An interface to the Stanford Validity Checker (SVC) is available through the
  1906 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1907 are proved automatically.  SVC must be installed separately, and its results
  1908 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1909 invocation of the underlying oracle).  For SVC see
  1910   http://verify.stanford.edu/SVC
  1911 
  1912 * IsaMakefile: the HOL-Real target now builds an actual image;
  1913 
  1914 
  1915 ** HOL misc **
  1916 
  1917 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1918 (in Isabelle/Isar) -- by Gertrud Bauer;
  1919 
  1920 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1921 analysis for assembly languages with subtypes;
  1922 
  1923 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1924 -- avoids syntactic ambiguities and treats state, transition, and
  1925 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1926 changed syntax and (many) tactics;
  1927 
  1928 * HOL/inductive: Now also handles more general introduction rules such
  1929   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1930   theorems are now maintained within the theory (maintained via the
  1931   "mono" attribute);
  1932 
  1933 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1934   (using function types) such as
  1935 
  1936   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1937 
  1938 * HOL/record: record_simproc (part of the default simpset) takes care
  1939 of selectors applied to updated records; record_split_tac is no longer
  1940 part of the default claset; update_defs may now be removed from the
  1941 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1942 
  1943   claset_ref () := claset() addSWrapper record_split_wrapper;
  1944   Delsimprocs [record_simproc]
  1945 
  1946 * HOL/typedef: fixed type inference for representing set; type
  1947 arguments now have to occur explicitly on the rhs as type constraints;
  1948 
  1949 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1950 names rather than an ML expression;
  1951 
  1952 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1953 supplied later.  Program schemes can be defined, such as
  1954     "While B C s = (if B s then While B C (C s) else s)"
  1955 where the well-founded relation can be chosen after B and C have been given.
  1956 
  1957 * HOL/List: the constructors of type list are now Nil and Cons;
  1958 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1959 course, ML tools referring to List.list.op # etc. have to be adapted;
  1960 
  1961 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1962 disabled by default; run isabelle with option -m HOL to get back to
  1963 the original Gordon/HOL-style output;
  1964 
  1965 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1966 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1967 
  1968 * HOL basic syntax simplified (more orthogonal): all variants of
  1969 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1970 Eps operator is provided as well: "SOME x. P[x]";
  1971 
  1972 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1973 
  1974 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1975 thus available for user theories;
  1976 
  1977 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1978 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1979 time;
  1980 
  1981 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1982 several times and then mp;
  1983 
  1984 
  1985 *** LK ***
  1986 
  1987 * the notation <<...>> is now available as a notation for sequences of
  1988 formulas;
  1989 
  1990 * the simplifier is now installed
  1991 
  1992 * the axiom system has been generalized (thanks to Soren Heilmann)
  1993 
  1994 * the classical reasoner now has a default rule database
  1995 
  1996 
  1997 *** ZF ***
  1998 
  1999 * new primrec section allows primitive recursive functions to be given
  2000 directly (as in HOL) over datatypes and the natural numbers;
  2001 
  2002 * new tactics induct_tac and exhaust_tac for induction (or case
  2003 analysis) over datatypes and the natural numbers;
  2004 
  2005 * the datatype declaration of type T now defines the recursor T_rec;
  2006 
  2007 * simplification automatically does freeness reasoning for datatype
  2008 constructors;
  2009 
  2010 * automatic type-inference, with AddTCs command to insert new
  2011 type-checking rules;
  2012 
  2013 * datatype introduction rules are now added as Safe Introduction rules
  2014 to the claset;
  2015 
  2016 * the syntax "if P then x else y" is now available in addition to
  2017 if(P,x,y);
  2018 
  2019 
  2020 *** Internal programming interfaces ***
  2021 
  2022 * tuned simplifier trace output; new flag debug_simp;
  2023 
  2024 * structures Vartab / Termtab (instances of TableFun) offer efficient
  2025 tables indexed by indexname_ord / term_ord (compatible with aconv);
  2026 
  2027 * AxClass.axclass_tac lost the theory argument;
  2028 
  2029 * tuned current_goals_markers semantics: begin / end goal avoids
  2030 printing empty lines;
  2031 
  2032 * removed prs and prs_fn hook, which was broken because it did not
  2033 include \n in its semantics, forcing writeln to add one
  2034 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  2035 string -> unit if you really want to output text without newline;
  2036 
  2037 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  2038 plain output, interface builders may have to enable 'isabelle_font'
  2039 mode to get Isabelle font glyphs as before;
  2040 
  2041 * refined token_translation interface; INCOMPATIBILITY: output length
  2042 now of type real instead of int;
  2043 
  2044 * theory loader actions may be traced via new ThyInfo.add_hook
  2045 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  2046 your own database of information attached to *whole* theories -- as
  2047 opposed to intra-theory data slots offered via TheoryDataFun;
  2048 
  2049 * proper handling of dangling sort hypotheses (at last!);
  2050 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  2051 extra sort hypotheses that can be witnessed from the type signature;
  2052 the force_strip_shyps flag is gone, any remaining shyps are simply
  2053 left in the theorem (with a warning issued by strip_shyps_warning);
  2054 
  2055 
  2056 
  2057 New in Isabelle98-1 (October 1998)
  2058 ----------------------------------
  2059 
  2060 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2061 
  2062 * several changes of automated proof tools;
  2063 
  2064 * HOL: major changes to the inductive and datatype packages, including
  2065 some minor incompatibilities of theory syntax;
  2066 
  2067 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  2068 called `inj_on';
  2069 
  2070 * HOL: removed duplicate thms in Arith:
  2071   less_imp_add_less  should be replaced by  trans_less_add1
  2072   le_imp_add_le      should be replaced by  trans_le_add1
  2073 
  2074 * HOL: unary minus is now overloaded (new type constraints may be
  2075 required);
  2076 
  2077 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  2078 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  2079 now taken as an integer constant.
  2080 
  2081 * Pure: ML function 'theory_of' renamed to 'theory';
  2082 
  2083 
  2084 *** Proof tools ***
  2085 
  2086 * Simplifier:
  2087   1. Asm_full_simp_tac is now more aggressive.
  2088      1. It will sometimes reorient premises if that increases their power to
  2089         simplify.
  2090      2. It does no longer proceed strictly from left to right but may also
  2091         rotate premises to achieve further simplification.
  2092      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  2093      old Asm_full_simp_tac in that it does not rotate premises.
  2094   2. The simplifier now knows a little bit about nat-arithmetic.
  2095 
  2096 * Classical reasoner: wrapper mechanism for the classical reasoner now
  2097 allows for selected deletion of wrappers, by introduction of names for
  2098 wrapper functionals.  This implies that addbefore, addSbefore,
  2099 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  2100 and that adding two tactics with the same name overwrites the first
  2101 one (emitting a warning).
  2102   type wrapper = (int -> tactic) -> (int -> tactic)
  2103   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  2104   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  2105   delWrapper, delSWrapper: claset *  string            -> claset
  2106   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  2107 
  2108 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  2109 semantics; addbefore now affects only the unsafe part of step_tac
  2110 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  2111 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  2112 by Force_tac;
  2113 
  2114 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  2115 compWrapper; added safe wrapper (and access functions for it);
  2116 
  2117 * HOL/split_all_tac is now much faster and fails if there is nothing
  2118 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  2119 and the names of the automatically generated variables have changed.
  2120 split_all_tac has moved within claset() from unsafe wrappers to safe
  2121 wrappers, which means that !!-bound variables are split much more
  2122 aggressively, and safe_tac and clarify_tac now split such variables.
  2123 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  2124 Note: the same holds for record_split_tac, which does the job of
  2125 split_all_tac for record fields.
  2126 
  2127 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  2128 permanently to the default simpset using Addsplits just like
  2129 Addsimps. They can be removed via Delsplits just like
  2130 Delsimps. Lower-case versions are also available.
  2131 
  2132 * HOL/Simplifier: The rule split_if is now part of the default
  2133 simpset. This means that the simplifier will eliminate all occurrences
  2134 of if-then-else in the conclusion of a goal. To prevent this, you can
  2135 either remove split_if completely from the default simpset by
  2136 `Delsplits [split_if]' or remove it in a specific call of the
  2137 simplifier using `... delsplits [split_if]'.  You can also add/delete
  2138 other case splitting rules to/from the default simpset: every datatype
  2139 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  2140 t is the name of the datatype).
  2141 
  2142 * Classical reasoner / Simplifier combination: new force_tac (and
  2143 derivatives Force_tac, force) combines rewriting and classical
  2144 reasoning (and whatever other tools) similarly to auto_tac, but is
  2145 aimed to solve the given subgoal completely.
  2146 
  2147 
  2148 *** General ***
  2149 
  2150 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  2151 and `goalw': the theory is no longer needed as an explicit argument -
  2152 the current theory context is used; assumptions are no longer returned
  2153 at the ML-level unless one of them starts with ==> or !!; it is
  2154 recommended to convert to these new commands using isatool fixgoal
  2155 (backup your sources first!);
  2156 
  2157 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  2158 the current theory context, and 'theory' to lookup stored theories;
  2159 
  2160 * new theory section 'locale' for declaring constants, assumptions and
  2161 definitions that have local scope;
  2162 
  2163 * new theory section 'nonterminals' for purely syntactic types;
  2164 
  2165 * new theory section 'setup' for generic ML setup functions
  2166 (e.g. package initialization);
  2167 
  2168 * the distribution now includes Isabelle icons: see
  2169 lib/logo/isabelle-{small,tiny}.xpm;
  2170 
  2171 * isatool install - install binaries with absolute references to
  2172 ISABELLE_HOME/bin;
  2173 
  2174 * isatool logo -- create instances of the Isabelle logo (as EPS);
  2175 
  2176 * print mode 'emacs' reserved for Isamode;
  2177 
  2178 * support multiple print (ast) translations per constant name;
  2179 
  2180 * theorems involving oracles are now printed with a suffixed [!];
  2181 
  2182 
  2183 *** HOL ***
  2184 
  2185 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  2186 
  2187 * HOL/inductive package reorganized and improved: now supports mutual
  2188 definitions such as
  2189 
  2190   inductive EVEN ODD
  2191     intrs
  2192       null "0 : EVEN"
  2193       oddI "n : EVEN ==> Suc n : ODD"
  2194       evenI "n : ODD ==> Suc n : EVEN"
  2195 
  2196 new theorem list "elims" contains an elimination rule for each of the
  2197 recursive sets; inductive definitions now handle disjunctive premises
  2198 correctly (also ZF);
  2199 
  2200 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  2201 "mutual_induct" no longer exists - the induction rule is always
  2202 contained in "induct";
  2203 
  2204 
  2205 * HOL/datatype package re-implemented and greatly improved: now
  2206 supports mutually recursive datatypes such as
  2207 
  2208   datatype
  2209     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  2210             | SUM ('a aexp) ('a aexp)
  2211             | DIFF ('a aexp) ('a aexp)
  2212             | NUM 'a
  2213   and
  2214     'a bexp = LESS ('a aexp) ('a aexp)
  2215             | AND ('a bexp) ('a bexp)
  2216             | OR ('a bexp) ('a bexp)
  2217 
  2218 as well as indirectly recursive datatypes such as
  2219 
  2220   datatype
  2221     ('a, 'b) term = Var 'a
  2222                   | App 'b ((('a, 'b) term) list)
  2223 
  2224 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  2225 induction on mutually / indirectly recursive datatypes.
  2226 
  2227 Primrec equations are now stored in theory and can be accessed via
  2228 <function_name>.simps.
  2229 
  2230 INCOMPATIBILITIES:
  2231 
  2232   - Theories using datatypes must now have theory Datatype as an
  2233     ancestor.
  2234   - The specific <typename>.induct_tac no longer exists - use the
  2235     generic induct_tac instead.
  2236   - natE has been renamed to nat.exhaust - use exhaust_tac
  2237     instead of res_inst_tac ... natE. Note that the variable
  2238     names in nat.exhaust differ from the names in natE, this
  2239     may cause some "fragile" proofs to fail.
  2240   - The theorems split_<typename>_case and split_<typename>_case_asm
  2241     have been renamed to <typename>.split and <typename>.split_asm.
  2242   - Since default sorts of type variables are now handled correctly,
  2243     some datatype definitions may have to be annotated with explicit
  2244     sort constraints.
  2245   - Primrec definitions no longer require function name and type
  2246     of recursive argument.
  2247 
  2248 Consider using isatool fixdatatype to adapt your theories and proof
  2249 scripts to the new package (backup your sources first!).
  2250 
  2251 
  2252 * HOL/record package: considerably improved implementation; now
  2253 includes concrete syntax for record types, terms, updates; theorems
  2254 for surjective pairing and splitting !!-bound record variables; proof
  2255 support is as follows:
  2256 
  2257   1) standard conversions (selectors or updates applied to record
  2258 constructor terms) are part of the standard simpset;
  2259 
  2260   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  2261 made part of standard simpset and claset via addIffs;
  2262 
  2263   3) a tactic for record field splitting (record_split_tac) is part of
  2264 the standard claset (addSWrapper);
  2265 
  2266 To get a better idea about these rules you may retrieve them via
  2267 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  2268 the name of your record type.
  2269 
  2270 The split tactic 3) conceptually simplifies by the following rule:
  2271 
  2272   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  2273 
  2274 Thus any record variable that is bound by meta-all will automatically
  2275 blow up into some record constructor term, consequently the
  2276 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  2277 solve record problems automatically.
  2278 
  2279 
  2280 * reorganized the main HOL image: HOL/Integ and String loaded by
  2281 default; theory Main includes everything;
  2282 
  2283 * automatic simplification of integer sums and comparisons, using cancellation;
  2284 
  2285 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  2286 
  2287 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  2288 
  2289 * many new identities for unions, intersections, set difference, etc.;
  2290 
  2291 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  2292 called split_if, split_split, split_sum_case and split_nat_case (to go
  2293 with add/delsplits);
  2294 
  2295 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  2296 (?x::unit) = (); this is made part of the default simpset, which COULD
  2297 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  2298 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  2299 unit_abs_eta_conv is added in order to counter the effect of
  2300 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  2301 %u.f();
  2302 
  2303 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  2304 makes more sense);
  2305 
  2306 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2307   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2308   disjointness reasoning but breaking a few old proofs.
  2309 
  2310 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  2311 to 'converse' from 'inverse' (for compatibility with ZF and some
  2312 literature);
  2313 
  2314 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  2315 the well-founded relation;
  2316 
  2317 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  2318     Compl A.  The "Compl" syntax remains available as input syntax for this
  2319     release ONLY.
  2320 
  2321 * HOL/Update: new theory of function updates:
  2322     f(a:=b) == %x. if x=a then b else f x
  2323 may also be iterated as in f(a:=b,c:=d,...);
  2324 
  2325 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  2326 
  2327 * HOL/List:
  2328   - new function list_update written xs[i:=v] that updates the i-th
  2329     list position. May also be iterated as in xs[i:=a,j:=b,...].
  2330   - new function `upt' written [i..j(] which generates the list
  2331     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  2332     bound write [i..j], which is a shorthand for [i..j+1(].
  2333   - new lexicographic orderings and corresponding wellfoundedness theorems.
  2334 
  2335 * HOL/Arith:
  2336   - removed 'pred' (predecessor) function;
  2337   - generalized some theorems about n-1;
  2338   - many new laws about "div" and "mod";
  2339   - new laws about greatest common divisors (see theory ex/Primes);
  2340 
  2341 * HOL/Relation: renamed the relational operator r^-1 "converse"
  2342 instead of "inverse";
  2343 
  2344 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  2345   of the multiset ordering;
  2346 
  2347 * directory HOL/Real: a construction of the reals using Dedekind cuts
  2348   (not included by default);
  2349 
  2350 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  2351 
  2352 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  2353   programs, i.e. different program variables may have different types.
  2354 
  2355 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2356   [previously, this check worked only if the rewrite rule was unconditional]
  2357   Now rew can involve either definitions or equalities (either == or =).
  2358 
  2359 
  2360 *** ZF ***
  2361 
  2362 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  2363   only the theorems proved on ZF.ML;
  2364 
  2365 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2366   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2367   disjointness reasoning but breaking a few old proofs.
  2368 
  2369 * ZF/Update: new theory of function updates
  2370     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  2371   may also be iterated as in f(a:=b,c:=d,...);
  2372 
  2373 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  2374 
  2375 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2376   [previously, this check worked only if the rewrite rule was unconditional]
  2377   Now rew can involve either definitions or equalities (either == or =).
  2378 
  2379 * case_tac provided for compatibility with HOL
  2380     (like the old excluded_middle_tac, but with subgoals swapped)
  2381 
  2382 
  2383 *** Internal programming interfaces ***
  2384 
  2385 * Pure: several new basic modules made available for general use, see
  2386 also src/Pure/README;
  2387 
  2388 * improved the theory data mechanism to support encapsulation (data
  2389 kind name replaced by private Object.kind, acting as authorization
  2390 key); new type-safe user interface via functor TheoryDataFun; generic
  2391 print_data function becomes basically useless;
  2392 
  2393 * removed global_names compatibility flag -- all theory declarations
  2394 are qualified by default;
  2395 
  2396 * module Pure/Syntax now offers quote / antiquote translation
  2397 functions (useful for Hoare logic etc. with implicit dependencies);
  2398 see HOL/ex/Antiquote for an example use;
  2399 
  2400 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2401 cterm -> thm;
  2402 
  2403 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2404 subgoal;
  2405 
  2406 * Display.print_goals function moved to Locale.print_goals;
  2407 
  2408 * standard print function for goals supports current_goals_markers
  2409 variable for marking begin of proof, end of proof, start of goal; the
  2410 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2411 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2412 for example;
  2413 
  2414 
  2415 
  2416 New in Isabelle98 (January 1998)
  2417 --------------------------------
  2418 
  2419 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2420 
  2421 * changed lexical syntax of terms / types: dots made part of long
  2422 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2423 
  2424 * simpset (and claset) reference variable replaced by functions
  2425 simpset / simpset_ref;
  2426 
  2427 * no longer supports theory aliases (via merge) and non-trivial
  2428 implicit merge of thms' signatures;
  2429 
  2430 * most internal names of constants changed due to qualified names;
  2431 
  2432 * changed Pure/Sequence interface (see Pure/seq.ML);
  2433 
  2434 
  2435 *** General Changes ***
  2436 
  2437 * hierachically structured name spaces (for consts, types, axms, thms
  2438 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2439 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2440 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2441 long_names for fully qualified output names; NOTE: ML programs
  2442 (special tactics, packages etc.) referring to internal names may have
  2443 to be adapted to cope with fully qualified names; in case of severe
  2444 backward campatibility problems try setting 'global_names' at compile
  2445 time to have enrything declared within a flat name space; one may also
  2446 fine tune name declarations in theories via the 'global' and 'local'
  2447 section;
  2448 
  2449 * reimplemented the implicit simpset and claset using the new anytype
  2450 data filed in signatures; references simpset:simpset ref etc. are
  2451 replaced by functions simpset:unit->simpset and
  2452 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2453 to patch your ML files accordingly;
  2454 
  2455 * HTML output now includes theory graph data for display with Java
  2456 applet or isatool browser; data generated automatically via isatool
  2457 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2458 
  2459 * defs may now be conditional; improved rewrite_goals_tac to handle
  2460 conditional equations;
  2461 
  2462 * defs now admits additional type arguments, using TYPE('a) syntax;
  2463 
  2464 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2465 creates a new theory node; implicit merge of thms' signatures is
  2466 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2467 transfer:theory->thm->thm in (rare) cases;
  2468 
  2469 * improved handling of draft signatures / theories; draft thms (and
  2470 ctyps, cterms) are automatically promoted to real ones;
  2471 
  2472 * slightly changed interfaces for oracles: admit many per theory, named
  2473 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2474 
  2475 * print_goals: optional output of const types (set show_consts and
  2476 show_types);
  2477 
  2478 * improved output of warnings (###) and errors (***);
  2479 
  2480 * subgoal_tac displays a warning if the new subgoal has type variables;
  2481 
  2482 * removed old README and Makefiles;
  2483 
  2484 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2485 
  2486 * removed obsolete init_pps and init_database;
  2487 
  2488 * deleted the obsolete tactical STATE, which was declared by
  2489     fun STATE tacfun st = tacfun st st;
  2490 
  2491 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2492 (which abbreviates $HOME);
  2493 
  2494 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2495 use isatool fixseq to adapt your ML programs (this works for fully
  2496 qualified references to the Sequence structure only!);
  2497 
  2498 * use_thy no longer requires writable current directory; it always
  2499 reloads .ML *and* .thy file, if either one is out of date;
  2500 
  2501 
  2502 *** Classical Reasoner ***
  2503 
  2504 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2505 tactics that use classical reasoning to simplify a subgoal without
  2506 splitting it into several subgoals;
  2507 
  2508 * Safe_tac: like safe_tac but uses the default claset;
  2509 
  2510 
  2511 *** Simplifier ***
  2512 
  2513 * added simplification meta rules:
  2514     (asm_)(full_)simplify: simpset -> thm -> thm;
  2515 
  2516 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2517 logics (again);
  2518 
  2519 * added prems argument to simplification procedures;
  2520 
  2521 * HOL, FOL, ZF: added infix function `addsplits':
  2522   instead of `<simpset> setloop (split_tac <thms>)'
  2523   you can simply write `<simpset> addsplits <thms>'
  2524 
  2525 
  2526 *** Syntax ***
  2527 
  2528 * TYPE('a) syntax for type reflection terms;
  2529 
  2530 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2531 
  2532 * pretty printer: changed order of mixfix annotation preference (again!);
  2533 
  2534 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2535 
  2536 
  2537 *** HOL ***
  2538 
  2539 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2540   with `addloop' of the simplifier to faciliate case splitting in premises.
  2541 
  2542 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2543 
  2544 * HOL/Auth: new protocol proofs including some for the Internet
  2545   protocol TLS;
  2546 
  2547 * HOL/Map: new theory of `maps' a la VDM;
  2548 
  2549 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2550 cancelling out common nat summands from =, <, <= (in)equalities, or
  2551 differences; simplification procedures nat_cancel_factor for
  2552 cancelling common factor from =, <, <= (in)equalities over natural
  2553 sums; nat_cancel contains both kinds of procedures, it is installed by
  2554 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2555 
  2556 * HOL/simplifier: terms of the form
  2557   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2558   are rewritten to
  2559   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2560   and those of the form
  2561   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2562   are rewritten to
  2563   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2564 
  2565 * HOL/datatype
  2566   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2567 
  2568   P(t_case f1 ... fn x) =
  2569      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2570         ...
  2571        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2572      )
  2573 
  2574   and a theorem `split_t_case_asm' of the form
  2575 
  2576   P(t_case f1 ... fn x) =
  2577     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2578         ...
  2579        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2580      )
  2581   which can be added to a simpset via `addsplits'. The existing theorems
  2582   expand_list_case and expand_option_case have been renamed to
  2583   split_list_case and split_option_case.
  2584 
  2585 * HOL/Arithmetic:
  2586   - `pred n' is automatically converted to `n-1'.
  2587     Users are strongly encouraged not to use `pred' any longer,
  2588     because it will disappear altogether at some point.
  2589   - Users are strongly encouraged to write "0 < n" rather than
  2590     "n ~= 0". Theorems and proof tools have been modified towards this
  2591     `standard'.
  2592 
  2593 * HOL/Lists:
  2594   the function "set_of_list" has been renamed "set" (and its theorems too);
  2595   the function "nth" now takes its arguments in the reverse order and
  2596   has acquired the infix notation "!" as in "xs!n".
  2597 
  2598 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2599 
  2600 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2601   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2602 
  2603 * HOL/record: extensible records with schematic structural subtyping
  2604 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2605 still lacks various theorems and concrete record syntax;
  2606 
  2607 
  2608 *** HOLCF ***
  2609 
  2610 * removed "axioms" and "generated by" sections;
  2611 
  2612 * replaced "ops" section by extended "consts" section, which is capable of
  2613   handling the continuous function space "->" directly;
  2614 
  2615 * domain package:
  2616   . proves theorems immediately and stores them in the theory,
  2617   . creates hierachical name space,
  2618   . now uses normal mixfix annotations (instead of cinfix...),
  2619   . minor changes to some names and values (for consistency),
  2620   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2621   . separator between mutual domain defs: changed "," to "and",
  2622   . improved handling of sort constraints;  now they have to
  2623     appear on the left-hand side of the equations only;
  2624 
  2625 * fixed LAM <x,y,zs>.b syntax;
  2626 
  2627 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2628 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2629 
  2630 
  2631 *** FOL and ZF ***
  2632 
  2633 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2634   with `addloop' of the simplifier to faciliate case splitting in premises.
  2635 
  2636 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2637 in HOL, they strip ALL and --> from proved theorems;
  2638 
  2639 
  2640 
  2641 New in Isabelle94-8 (May 1997)
  2642 ------------------------------
  2643 
  2644 *** General Changes ***
  2645 
  2646 * new utilities to build / run / maintain Isabelle etc. (in parts
  2647 still somewhat experimental); old Makefiles etc. still functional;
  2648 
  2649 * new 'Isabelle System Manual';
  2650 
  2651 * INSTALL text, together with ./configure and ./build scripts;
  2652 
  2653 * reimplemented type inference for greater efficiency, better error
  2654 messages and clean internal interface;
  2655 
  2656 * prlim command for dealing with lots of subgoals (an easier way of
  2657 setting goals_limit);
  2658 
  2659 
  2660 *** Syntax ***
  2661 
  2662 * supports alternative (named) syntax tables (parser and pretty
  2663 printer); internal interface is provided by add_modesyntax(_i);
  2664 
  2665 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2666 be used in conjunction with the Isabelle symbol font; uses the
  2667 "symbols" syntax table;
  2668 
  2669 * added token_translation interface (may translate name tokens in
  2670 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2671 the current print_mode); IMPORTANT: user print translation functions
  2672 are responsible for marking newly introduced bounds
  2673 (Syntax.mark_boundT);
  2674 
  2675 * token translations for modes "xterm" and "xterm_color" that display
  2676 names in bold, underline etc. or colors (which requires a color
  2677 version of xterm);
  2678 
  2679 * infixes may now be declared with names independent of their syntax;
  2680 
  2681 * added typed_print_translation (like print_translation, but may
  2682 access type of constant);
  2683 
  2684 
  2685 *** Classical Reasoner ***
  2686 
  2687 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2688 some limitations.  Blast_tac...
  2689   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2690   + ignores elimination rules that don't have the correct format
  2691         (the conclusion MUST be a formula variable)
  2692   + ignores types, which can make HOL proofs fail
  2693   + rules must not require higher-order unification, e.g. apply_type in ZF
  2694     [message "Function Var's argument not a bound variable" relates to this]
  2695   + its proof strategy is more general but can actually be slower
  2696 
  2697 * substitution with equality assumptions no longer permutes other
  2698 assumptions;
  2699 
  2700 * minor changes in semantics of addafter (now called addaltern); renamed
  2701 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2702 (and access functions for it);
  2703 
  2704 * improved combination of classical reasoner and simplifier:
  2705   + functions for handling clasimpsets
  2706   + improvement of addss: now the simplifier is called _after_ the
  2707     safe steps.
  2708   + safe variant of addss called addSss: uses safe simplifications
  2709     _during_ the safe steps. It is more complete as it allows multiple
  2710     instantiations of unknowns (e.g. with slow_tac).
  2711 
  2712 *** Simplifier ***
  2713 
  2714 * added interface for simplification procedures (functions that
  2715 produce *proven* rewrite rules on the fly, depending on current
  2716 redex);
  2717 
  2718 * ordering on terms as parameter (used for ordered rewriting);
  2719 
  2720 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2721 
  2722 * the solver is now split into a safe and an unsafe part.
  2723 This should be invisible for the normal user, except that the
  2724 functions setsolver and addsolver have been renamed to setSolver and
  2725 addSolver; added safe_asm_full_simp_tac;
  2726 
  2727 
  2728 *** HOL ***
  2729 
  2730 * a generic induction tactic `induct_tac' which works for all datatypes and
  2731 also for type `nat';
  2732 
  2733 * a generic case distinction tactic `exhaust_tac' which works for all
  2734 datatypes and also for type `nat';
  2735 
  2736 * each datatype comes with a function `size';
  2737 
  2738 * patterns in case expressions allow tuple patterns as arguments to
  2739 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2740 
  2741 * primrec now also works with type nat;
  2742 
  2743 * recdef: a new declaration form, allows general recursive functions to be
  2744 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2745 
  2746 * the constant for negation has been renamed from "not" to "Not" to
  2747 harmonize with FOL, ZF, LK, etc.;
  2748 
  2749 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2750 infinite lists;
  2751 
  2752 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2753 
  2754 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2755 problems in commutative rings, using axiomatic type classes for + and *;
  2756 
  2757 * more examples in HOL/MiniML and HOL/Auth;
  2758 
  2759 * more default rewrite rules for quantifiers, union/intersection;
  2760 
  2761 * a new constant `arbitrary == @x.False';
  2762 
  2763 * HOLCF/IOA replaces old HOL/IOA;
  2764 
  2765 * HOLCF changes: derived all rules and arities
  2766   + axiomatic type classes instead of classes
  2767   + typedef instead of faking type definitions
  2768   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2769   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2770   + eliminated the types void, one, tr
  2771   + use unit lift and bool lift (with translations) instead of one and tr
  2772   + eliminated blift from Lift3.thy (use Def instead of blift)
  2773   all eliminated rules are derived as theorems --> no visible changes ;
  2774 
  2775 
  2776 *** ZF ***
  2777 
  2778 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2779 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2780 as ZF_cs addSIs [equalityI];
  2781 
  2782 
  2783 
  2784 New in Isabelle94-7 (November 96)
  2785 ---------------------------------
  2786 
  2787 * allowing negative levels (as offsets) in prlev and choplev;
  2788 
  2789 * super-linear speedup for large simplifications;
  2790 
  2791 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2792 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2793 FAIL); can suppress it using the command Delsimps (ex_simps @
  2794 all_simps); De Morgan laws are also now included, by default;
  2795 
  2796 * improved printing of ==>  :  ~:
  2797 
  2798 * new object-logic "Sequents" adds linear logic, while replacing LK
  2799 and Modal (thanks to Sara Kalvala);
  2800 
  2801 * HOL/Auth: correctness proofs for authentication protocols;
  2802 
  2803 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2804 examples on HOL/Auth);
  2805 
  2806 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2807 the rewriter and classical reasoner simultaneously;
  2808 
  2809 * function uresult no longer returns theorems in "standard" format;
  2810 regain previous version by: val uresult = standard o uresult;
  2811 
  2812 
  2813 
  2814 New in Isabelle94-6
  2815 -------------------
  2816 
  2817 * oracles -- these establish an interface between Isabelle and trusted
  2818 external reasoners, which may deliver results as theorems;
  2819 
  2820 * proof objects (in particular record all uses of oracles);
  2821 
  2822 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2823 
  2824 * "constdefs" section in theory files;
  2825 
  2826 * "primrec" section (HOL) no longer requires names;
  2827 
  2828 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2829 
  2830 
  2831 
  2832 New in Isabelle94-5
  2833 -------------------
  2834 
  2835 * reduced space requirements;
  2836 
  2837 * automatic HTML generation from theories;
  2838 
  2839 * theory files no longer require "..." (quotes) around most types;
  2840 
  2841 * new examples, including two proofs of the Church-Rosser theorem;
  2842 
  2843 * non-curried (1994) version of HOL is no longer distributed;
  2844 
  2845 
  2846 
  2847 New in Isabelle94-4
  2848 -------------------
  2849 
  2850 * greatly reduced space requirements;
  2851 
  2852 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2853 
  2854 * searchable theorem database (see the section "Retrieving theorems" on
  2855 page 8 of the Reference Manual);
  2856 
  2857 * new examples, including Grabczewski's monumental case study of the
  2858 Axiom of Choice;
  2859 
  2860 * The previous version of HOL renamed to Old_HOL;
  2861 
  2862 * The new version of HOL (previously called CHOL) uses a curried syntax
  2863 for functions.  Application looks like f a b instead of f(a,b);
  2864 
  2865 * Mutually recursive inductive definitions finally work in HOL;
  2866 
  2867 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2868 translates to the operator "split";
  2869 
  2870 
  2871 
  2872 New in Isabelle94-3
  2873 -------------------
  2874 
  2875 * new infix operator, addss, allowing the classical reasoner to
  2876 perform simplification at each step of its search.  Example:
  2877         fast_tac (cs addss ss)
  2878 
  2879 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2880 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2881 look like (a,b) instead of <a,b>;
  2882 
  2883 * PLEASE NOTE: CHOL will eventually replace HOL!
  2884 
  2885 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2886 It translates to the operator "split".  A new theory of integers is available;
  2887 
  2888 * In ZF, integer numerals now denote two's-complement binary integers.
  2889 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2890 
  2891 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2892 of the Axiom of Choice;
  2893 
  2894 
  2895 
  2896 New in Isabelle94-2
  2897 -------------------
  2898 
  2899 * Significantly faster resolution;
  2900 
  2901 * the different sections in a .thy file can now be mixed and repeated
  2902 freely;
  2903 
  2904 * Database of theorems for FOL, HOL and ZF.  New
  2905 commands including qed, qed_goal and bind_thm store theorems in the database.
  2906 
  2907 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2908 a given theory (thms_of), or find out what theory a theorem was proved in
  2909 (theory_of_thm);
  2910 
  2911 * Bugs fixed in the inductive definition and datatype packages;
  2912 
  2913 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2914 and HOL_dup_cs obsolete;
  2915 
  2916 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2917 have been removed;
  2918 
  2919 * Simpler definition of function space in ZF;
  2920 
  2921 * new results about cardinal and ordinal arithmetic in ZF;
  2922 
  2923 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2924 types;
  2925 
  2926 
  2927 $Id$