NEWS
author paulson
Fri Oct 01 11:54:15 2004 +0200 (2004-10-01)
changeset 15223 e669fb5b0f5a
parent 15206 09d78ec709c7
child 15242 1a4b471b1afa
permissions -rw-r--r--
patch to "display"
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** General ***
     8 
     9 * Theory headers: the new header syntax for Isar theories is
    10 
    11   theory <name>
    12   imports <theory1> ... <theoryn>
    13   begin
    14 
    15   optionally also with a "files" section. The syntax
    16 
    17   theory <name> = <theory1> + ... + <theoryn>:
    18 
    19   will still be supported for some time but will eventually disappear.
    20   The syntax of old-style theories has not changed.
    21 
    22 * Provers/quasi.ML:  new transitivity reasoners for transitivity only
    23   and quasi orders.
    24 
    25 * Provers/trancl.ML:  new transitivity reasoner for transitive and
    26   reflexive-transitive closure of relations.
    27 
    28 * Provers/blast.ML:  new reference depth_limit to make blast's depth
    29   limit (previously hard-coded with a value of 20) user-definable.
    30 
    31 * Pure: considerably improved version of 'constdefs' command.  Now
    32   performs automatic type-inference of declared constants; additional
    33   support for local structure declarations (cf. locales and HOL
    34   records), see also isar-ref manual.  Potential INCOMPATIBILITY: need
    35   to observe strictly sequential dependencies of definitions within a
    36   single 'constdefs' section; moreover, the declared name needs to be
    37   an identifier.  If all fails, consider to fall back on 'consts' and
    38   'defs' separately.
    39 
    40 * Pure: improved indexed syntax and implicit structures.  First of
    41   all, indexed syntax provides a notational device for subscripted
    42   application, using the new syntax \<^bsub>term\<^esub> for arbitrary
    43   expressions.  Secondly, in a local context with structure
    44   declarations, number indexes \<^sub>n or the empty index (default
    45   number 1) refer to a certain fixed variable implicitly; option
    46   show_structs controls printing of implicit structures.  Typical
    47   applications of these concepts involve record types and locales.
    48 
    49 * Pure: clear separation of logical types and nonterminals, where the
    50   latter may only occur in 'syntax' specifications or type
    51   abbreviations.  Before that distinction was only partially
    52   implemented via type class "logic" vs. "{}".  Potential
    53   INCOMPATIBILITY in rare cases of improper use of 'types'/'consts'
    54   instead of 'nonterminals'/'syntax'.  Some very exotic syntax
    55   specifications may require further adaption (e.g. Cube/Base.thy).
    56 
    57 * Pure: removed obsolete type class "logic", use the top sort {}
    58   instead.  Note that non-logical types should be declared as
    59   'nonterminals' rather than 'types'.  INCOMPATIBILITY for new
    60   object-logic specifications.
    61 
    62 * Pure: print_tac now outputs the goal through the trace channel.
    63 
    64 * Pure: reference Namespace.unique_names included.  If true the
    65   (shortest) namespace-prefix is printed to disambiguate conflicts (as
    66   yet). If false the first entry wins (as during parsing). Default
    67   value is true.
    68 
    69 * Pure: tuned internal renaming of symbolic identifiers -- attach
    70   primes instead of base 26 numbers.
    71 
    72 * Pure/Syntax: inner syntax includes (*(*nested*) comments*).
    73 
    74 * Pure/Syntax: pretty pinter now supports unbreakable blocks,
    75   specified in mixfix annotations as "(00...)".
    76 
    77 * Pure/Syntax: 'advanced' translation functions (parse_translation
    78   etc.) may depend on the signature of the theory context being
    79   presently used for parsing/printing, see also isar-ref manual.
    80 
    81 * Pure/Simplifier: simplification procedures may now take the current
    82   simpset into account (cf. Simplifier.simproc(_i) / mk_simproc
    83   interface), which is very useful for calling the Simplifier
    84   recursively.  Minor INCOMPATIBILITY: the 'prems' argument of
    85   simprocs is gone -- use prems_of_ss on the simpset instead.
    86   Moreover, the low-level mk_simproc no longer applies Logic.varify
    87   internally, to allow for use in a context of fixed variables.
    88 
    89 * Provers: Simplifier and Classical Reasoner now support proof context
    90   dependent plug-ins (simprocs, solvers, wrappers etc.).  These extra
    91   components are stored in the theory and patched into the
    92   simpset/claset when used in an Isar proof context.  Context
    93   dependent components are maintained by the following theory
    94   operations:
    95 
    96     Simplifier.add_context_simprocs
    97     Simplifier.del_context_simprocs
    98     Simplifier.set_context_subgoaler
    99     Simplifier.reset_context_subgoaler
   100     Simplifier.add_context_looper
   101     Simplifier.del_context_looper
   102     Simplifier.add_context_unsafe_solver
   103     Simplifier.add_context_safe_solver
   104 
   105     Classical.add_context_safe_wrapper
   106     Classical.del_context_safe_wrapper
   107     Classical.add_context_unsafe_wrapper
   108     Classical.del_context_unsafe_wrapper
   109 
   110   IMPORTANT NOTE: proof tools (methods etc.) need to use
   111   local_simpset_of and local_claset_of to instead of the primitive
   112   Simplifier.get_local_simpset and Classical.get_local_claset,
   113   respectively, in order to see the context dependent fields!
   114 
   115 * Document preparation: antiquotations now provide the option
   116   'locale=NAME' to specify an alternative context used for evaluating
   117   and printing the subsequent argument, as in @{thm [locale=LC]
   118   fold_commute}, for example.
   119 
   120 * Document preparation: commands 'display_drafts' and 'print_drafts'
   121   perform simple output of raw sources.  Only those symbols that do
   122   not require additional LaTeX packages (depending on comments in
   123   isabellesym.sty) are displayed properly, everything else is left
   124   verbatim.  We use isatool display and isatool print as front ends;
   125   these are subject to the DVI_VIEWER and PRINT_COMMAND settings,
   126   respectively.
   127 
   128 * ML: output via the Isabelle channels of writeln/warning/error
   129   etc. is now passed through Output.output, with a hook for arbitrary
   130   transformations depending on the print_mode (cf. Output.add_mode --
   131   the first active mode that provides a output function wins).
   132   Already formatted output may be embedded into further text via
   133   Output.raw; the result of Pretty.string_of/str_of and derived
   134   functions (string_of_term/cterm/thm etc.) is already marked raw to
   135   accommodate easy composition of diagnostic messages etc.
   136   Programmers rarely need to care about Output.output or Output.raw at
   137   all, with some notable exceptions: Output.output is required when
   138   bypassing the standard channels (writeln etc.), or in token
   139   translations to produce properly formatted results; Output.raw is
   140   required when capturing already output material that will eventually
   141   be presented to the user a second time.  For the default print mode,
   142   both Output.output and Output.raw have no effect.
   143 
   144 
   145 *** Isar ***
   146 
   147 * Locales:
   148   - "includes" disallowed in declaration of named locales (command "locale").
   149   - Fixed parameter management in theorem generation for goals with "includes".
   150     INCOMPATIBILITY: rarely, the generated theorem statement is different.
   151  
   152 *** HOL ***
   153 
   154 * HOL/record: reimplementation of records. Improved scalability for
   155   records with many fields, avoiding performance problems for type
   156   inference. Records are no longer composed of nested field types, but
   157   of nested extension types. Therefore the record type only grows
   158   linear in the number of extensions and not in the number of fields.
   159   The top-level (users) view on records is preserved.  Potential
   160   INCOMPATIBILITY only in strange cases, where the theory depends on
   161   the old record representation. The type generated for a record is
   162   called <record_name>_ext_type.
   163 
   164 * HOL/record: Reference record_quick_and_dirty_sensitive can be
   165   enabled to skip the proofs triggered by a record definition or a
   166   simproc (if quick_and_dirty is enabled). Definitions of large
   167   records can take quite long.
   168 
   169 * HOL/record: "record_upd_simproc" for simplification of multiple
   170   record updates enabled by default.  Moreover, trivial updates are
   171   also removed: r(|x := x r|) = r.  INCOMPATIBILITY: old proofs break
   172   occasionally, since simplification is more powerful by default.
   173 
   174 * HOL: symbolic syntax of Hilbert Choice Operator is now as follows:
   175 
   176   syntax (epsilon)
   177     "_Eps" :: "[pttrn, bool] => 'a"    ("(3\<some>_./ _)" [0, 10] 10)
   178 
   179   The symbol \<some> is displayed as the alternative epsilon of LaTeX
   180   and x-symbol; use option '-m epsilon' to get it actually printed.
   181   Moreover, the mathematically important symbolic identifier
   182   \<epsilon> becomes available as variable, constant etc.
   183 
   184 * HOL/SetInterval: The syntax for open intervals has changed:
   185 
   186   Old         New
   187   {..n(}   -> {..<n}
   188   {)n..}   -> {n<..}
   189   {m..n(}  -> {m..<n}
   190   {)m..n}  -> {m<..n}
   191   {)m..n(} -> {m<..<n}
   192 
   193   The old syntax is still supported but will disappear in the future.
   194   For conversion use the following emacs search and replace patterns:
   195 
   196   {)\([^\.]*\)\.\.  ->  {\1<\.\.}
   197   \.\.\([^(}]*\)(}  ->  \.\.<\1}
   198 
   199   They are not perfect but work quite well.
   200 
   201 * HOL: The syntax for 'setsum', summation over finite sets, has changed:
   202 
   203   The syntax for 'setsum (%x. e) A' used to be '\<Sum>x:A. e'
   204   and is now either 'SUM x:A. e' or '\<Sum>x\<in>A. e'.
   205 
   206   There is new syntax for summation over finite sets:
   207 
   208   '\<Sum>x | P. e'    is the same as  'setsum (%x. e) {x. P}'
   209   '\<Sum>x=a..b. e'   is the same as  'setsum (%x. e) {a..b}'
   210   '\<Sum>x=a..<b. e'  is the same as  'setsum (%x. e) {a..<b}'
   211   '\<Sum>x<k. e'      is the same as  'setsum (%x. e) {..<k}'
   212 
   213   Function 'Summation' over nat is gone, its syntax '\<Sum>i<k. e'
   214   now translates into 'setsum' as above.
   215 
   216 * HOL/Simplifier:
   217 
   218   - Is now set up to reason about transitivity chains involving "trancl"
   219   (r^+) and "rtrancl" (r^*) by setting up tactics provided by
   220   Provers/trancl.ML as additional solvers.  INCOMPATIBILITY: old proofs break
   221   occasionally as simplification may now solve more goals than previously.
   222 
   223   - Converts x <= y into x = y if assumption y <= x is present.  Works for
   224   all partial orders (class "order"), in particular numbers and sets. For
   225   linear orders (e.g. numbers) it treats ~ x < y just like y <= x.
   226 
   227 * HOL: new 'isatool dimacs2hol' to convert files in DIMACS CNF format
   228   (containing Boolean satisfiability problems) into Isabelle/HOL theories.
   229 
   230 
   231 *** HOLCF ***
   232 
   233 * HOLCF: discontinued special version of 'constdefs' (which used to
   234   support continuous functions) in favor of the general Pure one with
   235   full type-inference.
   236 
   237 
   238 *** ZF ***
   239 
   240 * ZF/ex/{Group,Ring}: examples in abstract algebra, including the
   241   First Isomorphism Theorem (on quotienting by the kernel of a
   242   homomorphism).
   243 
   244 * ZF/Simplifier: install second copy of type solver that actually
   245   makes use of TC rules declared to Isar proof contexts (or locales);
   246   the old version is still required for ML proof scripts.
   247 
   248 
   249 
   250 New in Isabelle2004 (April 2004)
   251 --------------------------------
   252 
   253 *** General ***
   254 
   255 * Provers/order.ML:  new efficient reasoner for partial and linear orders.
   256   Replaces linorder.ML.
   257 
   258 * Pure: Greek letters (except small lambda, \<lambda>), as well as Gothic
   259   (\<aa>...\<zz>\<AA>...\<ZZ>), calligraphic (\<A>...\<Z>), and Euler
   260   (\<a>...\<z>), are now considered normal letters, and can therefore
   261   be used anywhere where an ASCII letter (a...zA...Z) has until
   262   now. COMPATIBILITY: This obviously changes the parsing of some
   263   terms, especially where a symbol has been used as a binder, say
   264   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed
   265   as an identifier.  Fix it by inserting a space around former
   266   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in
   267   existing theory and ML files.
   268 
   269 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.
   270 
   271 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now
   272   allowed in identifiers. Similar to Greek letters \<^isub> is now considered
   273   a normal (but invisible) letter. For multiple letter subscripts repeat
   274   \<^isub> like this: x\<^isub>1\<^isub>2.
   275 
   276 * Pure: There are now sub-/superscripts that can span more than one
   277   character. Text between \<^bsub> and \<^esub> is set in subscript in
   278   ProofGeneral and LaTeX, text between \<^bsup> and \<^esup> in
   279   superscript. The new control characters are not identifier parts.
   280 
   281 * Pure: Control-symbols of the form \<^raw:...> will literally print the
   282   content of "..." to the latex file instead of \isacntrl... . The "..."
   283   may consist of any printable characters excluding the end bracket >.
   284 
   285 * Pure: Using new Isar command "finalconsts" (or the ML functions
   286   Theory.add_finals or Theory.add_finals_i) it is now possible to
   287   declare constants "final", which prevents their being given a definition
   288   later.  It is useful for constants whose behaviour is fixed axiomatically
   289   rather than definitionally, such as the meta-logic connectives.
   290 
   291 * Pure: 'instance' now handles general arities with general sorts
   292   (i.e. intersections of classes),
   293 
   294 * Presentation: generated HTML now uses a CSS style sheet to make layout
   295   (somewhat) independent of content. It is copied from lib/html/isabelle.css.
   296   It can be changed to alter the colors/layout of generated pages.
   297 
   298 
   299 *** Isar ***
   300 
   301 * Tactic emulation methods rule_tac, erule_tac, drule_tac, frule_tac,
   302   cut_tac, subgoal_tac and thin_tac:
   303   - Now understand static (Isar) contexts.  As a consequence, users of Isar
   304     locales are no longer forced to write Isar proof scripts.
   305     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
   306     emulations.
   307   - INCOMPATIBILITY: names of variables to be instantiated may no
   308     longer be enclosed in quotes.  Instead, precede variable name with `?'.
   309     This is consistent with the instantiation attribute "where".
   310 
   311 * Attributes "where" and "of":
   312   - Now take type variables of instantiated theorem into account when reading
   313     the instantiation string.  This fixes a bug that caused instantiated
   314     theorems to have too special types in some circumstances.
   315   - "where" permits explicit instantiations of type variables.
   316 
   317 * Calculation commands "moreover" and "also" no longer interfere with
   318   current facts ("this"), admitting arbitrary combinations with "then"
   319   and derived forms.
   320 
   321 * Locales:
   322   - Goal statements involving the context element "includes" no longer
   323     generate theorems with internal delta predicates (those ending on
   324     "_axioms") in the premise.
   325     Resolve particular premise with <locale>.intro to obtain old form.
   326   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
   327     specification and "includes" elements in goal statement.
   328   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
   329     [intro?] and [elim?] (respectively) by default.
   330   - Experimental command for instantiation of locales in proof contexts:
   331         instantiate <label>[<attrs>]: <loc>
   332     Instantiates locale <loc> and adds all its theorems to the current context
   333     taking into account their attributes.  Label and attrs are optional
   334     modifiers, like in theorem declarations.  If present, names of
   335     instantiated theorems are qualified with <label>, and the attributes
   336     <attrs> are applied after any attributes these theorems might have already.
   337       If the locale has assumptions, a chained fact of the form
   338     "<loc> t1 ... tn" is expected from which instantiations of the parameters
   339     are derived.  The command does not support old-style locales declared
   340     with "locale (open)".
   341       A few (very simple) examples can be found in FOL/ex/LocaleInst.thy.
   342 
   343 * HOL: Tactic emulation methods induct_tac and case_tac understand static
   344   (Isar) contexts.
   345 
   346 
   347 *** HOL ***
   348 
   349 * Proof import: new image HOL4 contains the imported library from
   350   the HOL4 system with about 2500 theorems. It is imported by
   351   replaying proof terms produced by HOL4 in Isabelle. The HOL4 image
   352   can be used like any other Isabelle image.  See
   353   HOL/Import/HOL/README for more information.
   354 
   355 * Simplifier:
   356   - Much improved handling of linear and partial orders.
   357     Reasoners for linear and partial orders are set up for type classes
   358     "linorder" and "order" respectively, and are added to the default simpset
   359     as solvers.  This means that the simplifier can build transitivity chains
   360     to solve goals from the assumptions.
   361   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications
   362     of blast or auto after simplification become unnecessary because the goal
   363     is solved by simplification already.
   364 
   365 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws,
   366     all proved in axiomatic type classes for semirings, rings and fields.
   367 
   368 * Numerics:
   369   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are
   370     now formalized using the Ring_and_Field theory mentioned above.
   371   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently
   372     than before, because now they are set up once in a generic manner.
   373   - INCOMPATIBILITY: many type-specific arithmetic laws have gone.
   374     Look for the general versions in Ring_and_Field (and Power if they concern
   375     exponentiation).
   376 
   377 * Type "rat" of the rational numbers is now available in HOL-Complex.
   378 
   379 * Records:
   380   - Record types are now by default printed with their type abbreviation
   381     instead of the list of all field types. This can be configured via
   382     the reference "print_record_type_abbr".
   383   - Simproc "record_upd_simproc" for simplification of multiple updates added
   384     (not enabled by default).
   385   - Simproc "record_ex_sel_eq_simproc" to simplify EX x. sel r = x resp.
   386     EX x. x = sel r to True (not enabled by default).
   387   - Tactic "record_split_simp_tac" to split and simplify records added.
   388 
   389 * 'specification' command added, allowing for definition by
   390   specification.  There is also an 'ax_specification' command that
   391   introduces the new constants axiomatically.
   392 
   393 * arith(_tac) is now able to generate counterexamples for reals as well.
   394 
   395 * HOL-Algebra: new locale "ring" for non-commutative rings.
   396 
   397 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
   398   definitions, thanks to Sava Krsti\'{c} and John Matthews.
   399 
   400 * HOL-Matrix: a first theory for matrices in HOL with an application of
   401   matrix theory to linear programming.
   402 
   403 * Unions and Intersections:
   404   The latex output syntax of UN and INT has been changed
   405   from "\Union x \in A. B" to "\Union_{x \in A} B"
   406   i.e. the index formulae has become a subscript.
   407   Similarly for "\Union x. B", and for \Inter instead of \Union.
   408 
   409 * Unions and Intersections over Intervals:
   410   There is new short syntax "UN i<=n. A" for "UN i:{0..n}. A". There is
   411   also an x-symbol version with subscripts "\<Union>\<^bsub>i <= n\<^esub>. A"
   412   like in normal math, and corresponding versions for < and for intersection.
   413 
   414 * ML: the legacy theory structures Int and List have been removed. They had
   415   conflicted with ML Basis Library structures having the same names.
   416 
   417 * 'refute' command added to search for (finite) countermodels.  Only works
   418   for a fragment of HOL.  The installation of an external SAT solver is
   419   highly recommended.  See "HOL/Refute.thy" for details.
   420 
   421 * 'quickcheck' command: Allows to find counterexamples by evaluating
   422   formulae under an assignment of free variables to random values.
   423   In contrast to 'refute', it can deal with inductive datatypes,
   424   but cannot handle quantifiers. See "HOL/ex/Quickcheck_Examples.thy"
   425   for examples.
   426 
   427 
   428 *** HOLCF ***
   429 
   430 * Streams now come with concatenation and are part of the HOLCF image
   431 
   432 
   433 
   434 New in Isabelle2003 (May 2003)
   435 ------------------------------
   436 
   437 *** General ***
   438 
   439 * Provers/simplifier:
   440 
   441   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   442     Assumptions are now subject to complete mutual simplification,
   443     not just from left to right. The simplifier now preserves
   444     the order of assumptions.
   445 
   446     Potential INCOMPATIBILITY:
   447 
   448     -- simp sometimes diverges where the old version did
   449        not, e.g. invoking simp on the goal
   450 
   451         [| P (f x); y = x; f x = f y |] ==> Q
   452 
   453        now gives rise to the infinite reduction sequence
   454 
   455         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   456 
   457        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   458        kind of problem.
   459 
   460     -- Tactics combining classical reasoner and simplification (such as auto)
   461        are also affected by this change, because many of them rely on
   462        simp. They may sometimes diverge as well or yield a different numbers
   463        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   464        in case of problems. Sometimes subsequent calls to the classical
   465        reasoner will fail because a preceeding call to the simplifier too
   466        eagerly simplified the goal, e.g. deleted redundant premises.
   467 
   468   - The simplifier trace now shows the names of the applied rewrite rules
   469 
   470   - You can limit the number of recursive invocations of the simplifier
   471     during conditional rewriting (where the simplifie tries to solve the
   472     conditions before applying the rewrite rule):
   473     ML "simp_depth_limit := n"
   474     where n is an integer. Thus you can force termination where previously
   475     the simplifier would diverge.
   476 
   477   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   478 
   479   - No longer aborts on failed congruence proof.  Instead, the
   480     congruence is ignored.
   481 
   482 * Pure: New generic framework for extracting programs from constructive
   483   proofs. See HOL/Extraction.thy for an example instantiation, as well
   484   as HOL/Extraction for some case studies.
   485 
   486 * Pure: The main goal of the proof state is no longer shown by default, only
   487 the subgoals. This behaviour is controlled by a new flag.
   488    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   489 (ML: Proof.show_main_goal).
   490 
   491 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   492 rules whose conclusion matches subgoal 1:
   493       PG menu: Isabelle/Isar -> Show me -> matching rules
   494 The rules are ordered by how closely they match the subgoal.
   495 In particular, rules that solve a subgoal outright are displayed first
   496 (or rather last, the way they are printed).
   497 (ML: ProofGeneral.print_intros())
   498 
   499 * Pure: New flag trace_unify_fail causes unification to print
   500 diagnostic information (PG: in trace buffer) when it fails. This is
   501 useful for figuring out why single step proofs like rule, erule or
   502 assumption failed.
   503 
   504 * Pure: Locale specifications now produce predicate definitions
   505 according to the body of text (covering assumptions modulo local
   506 definitions); predicate "loc_axioms" covers newly introduced text,
   507 while "loc" is cumulative wrt. all included locale expressions; the
   508 latter view is presented only on export into the global theory
   509 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   510 on the old view without predicates;
   511 
   512 * Pure: predefined locales "var" and "struct" are useful for sharing
   513 parameters (as in CASL, for example); just specify something like
   514 ``var x + var y + struct M'' as import;
   515 
   516 * Pure: improved thms_containing: proper indexing of facts instead of
   517 raw theorems; check validity of results wrt. current name space;
   518 include local facts of proof configuration (also covers active
   519 locales), cover fixed variables in index; may use "_" in term
   520 specification; an optional limit for the number of printed facts may
   521 be given (the default is 40);
   522 
   523 * Pure: disallow duplicate fact bindings within new-style theory files
   524 (batch-mode only);
   525 
   526 * Provers: improved induct method: assumptions introduced by case
   527 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   528 the goal statement); "foo" still refers to all facts collectively;
   529 
   530 * Provers: the function blast.overloaded has been removed: all constants
   531 are regarded as potentially overloaded, which improves robustness in exchange
   532 for slight decrease in efficiency;
   533 
   534 * Provers/linorder: New generic prover for transitivity reasoning over
   535 linear orders.  Note: this prover is not efficient!
   536 
   537 * Isar: preview of problems to finish 'show' now produce an error
   538 rather than just a warning (in interactive mode);
   539 
   540 
   541 *** HOL ***
   542 
   543 * arith(_tac)
   544 
   545  - Produces a counter example if it cannot prove a goal.
   546    Note that the counter example may be spurious if the goal is not a formula
   547    of quantifier-free linear arithmetic.
   548    In ProofGeneral the counter example appears in the trace buffer.
   549 
   550  - Knows about div k and mod k where k is a numeral of type nat or int.
   551 
   552  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   553    linear arithmetic fails. This takes account of quantifiers and divisibility.
   554    Presburger arithmetic can also be called explicitly via presburger(_tac).
   555 
   556 * simp's arithmetic capabilities have been enhanced a bit: it now
   557 takes ~= in premises into account (by performing a case split);
   558 
   559 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   560 are distributed over a sum of terms;
   561 
   562 * New tactic "trans_tac" and method "trans" instantiate
   563 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   564 "<=", "<" and "=").
   565 
   566 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main
   567 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   568 
   569 * 'typedef' command has new option "open" to suppress the set
   570 definition;
   571 
   572 * functions Min and Max on finite sets have been introduced (theory
   573 Finite_Set);
   574 
   575 * attribute [symmetric] now works for relations as well; it turns
   576 (x,y) : R^-1 into (y,x) : R, and vice versa;
   577 
   578 * induct over a !!-quantified statement (say !!x1..xn):
   579   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   580 
   581 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   582 %x. None. Warning: empty_def now refers to the previously hidden definition
   583 of the empty set.
   584 
   585 * Algebra: formalization of classical algebra.  Intended as base for
   586 any algebraic development in Isabelle.  Currently covers group theory
   587 (up to Sylow's theorem) and ring theory (Universal Property of
   588 Univariate Polynomials).  Contributions welcome;
   589 
   590 * GroupTheory: deleted, since its material has been moved to Algebra;
   591 
   592 * Complex: new directory of the complex numbers with numeric constants,
   593 nonstandard complex numbers, and some complex analysis, standard and
   594 nonstandard (Jacques Fleuriot);
   595 
   596 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   597 
   598 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques
   599 Fleuriot);
   600 
   601 * Real/HahnBanach: updated and adapted to locales;
   602 
   603 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   604 Gray and Kramer);
   605 
   606 * UNITY: added the Meier-Sanders theory of progress sets;
   607 
   608 * MicroJava: bytecode verifier and lightweight bytecode verifier
   609 as abstract algorithms, instantiated to the JVM;
   610 
   611 * Bali: Java source language formalization. Type system, operational
   612 semantics, axiomatic semantics. Supported language features:
   613 classes, interfaces, objects,virtual methods, static methods,
   614 static/instance fields, arrays, access modifiers, definite
   615 assignment, exceptions.
   616 
   617 
   618 *** ZF ***
   619 
   620 * ZF/Constructible: consistency proof for AC (Gdel's constructible
   621 universe, etc.);
   622 
   623 * Main ZF: virtually all theories converted to new-style format;
   624 
   625 
   626 *** ML ***
   627 
   628 * Pure: Tactic.prove provides sane interface for internal proofs;
   629 omits the infamous "standard" operation, so this is more appropriate
   630 than prove_goalw_cterm in many situations (e.g. in simprocs);
   631 
   632 * Pure: improved error reporting of simprocs;
   633 
   634 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   635 up simprocs;
   636 
   637 
   638 *** Document preparation ***
   639 
   640 * uses \par instead of \\ for line breaks in theory text. This may
   641 shift some page breaks in large documents. To get the old behaviour
   642 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   643 
   644 * minimized dependencies of isabelle.sty and isabellesym.sty on
   645 other packages
   646 
   647 * \<euro> now needs package babel/greek instead of marvosym (which
   648 broke \Rightarrow)
   649 
   650 * normal size for \<zero>...\<nine> (uses \mathbf instead of
   651 textcomp package)
   652 
   653 
   654 
   655 New in Isabelle2002 (March 2002)
   656 --------------------------------
   657 
   658 *** Document preparation ***
   659 
   660 * greatly simplified document preparation setup, including more
   661 graceful interpretation of isatool usedir -i/-d/-D options, and more
   662 instructive isatool mkdir; users should basically be able to get
   663 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   664 users may run a separate document processing stage manually like this:
   665 "isatool usedir -D output HOL Test && isatool document Test/output";
   666 
   667 * theory dependency graph may now be incorporated into documents;
   668 isatool usedir -g true will produce session_graph.eps/.pdf for use
   669 with \includegraphics of LaTeX;
   670 
   671 * proper spacing of consecutive markup elements, especially text
   672 blocks after section headings;
   673 
   674 * support bold style (for single symbols only), input syntax is like
   675 this: "\<^bold>\<alpha>" or "\<^bold>A";
   676 
   677 * \<bullet> is now output as bold \cdot by default, which looks much
   678 better in printed text;
   679 
   680 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   681 note that these symbols are currently unavailable in Proof General /
   682 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   683 
   684 * isatool latex no longer depends on changed TEXINPUTS, instead
   685 isatool document copies the Isabelle style files to the target
   686 location;
   687 
   688 
   689 *** Isar ***
   690 
   691 * Pure/Provers: improved proof by cases and induction;
   692   - 'case' command admits impromptu naming of parameters (such as
   693     "case (Suc n)");
   694   - 'induct' method divinates rule instantiation from the inductive
   695     claim; no longer requires excessive ?P bindings for proper
   696     instantiation of cases;
   697   - 'induct' method properly enumerates all possibilities of set/type
   698     rules; as a consequence facts may be also passed through *type*
   699     rules without further ado;
   700   - 'induct' method now derives symbolic cases from the *rulified*
   701     rule (before it used to rulify cases stemming from the internal
   702     atomized version); this means that the context of a non-atomic
   703     statement becomes is included in the hypothesis, avoiding the
   704     slightly cumbersome show "PROP ?case" form;
   705   - 'induct' may now use elim-style induction rules without chaining
   706     facts, using ``missing'' premises from the goal state; this allows
   707     rules stemming from inductive sets to be applied in unstructured
   708     scripts, while still benefitting from proper handling of non-atomic
   709     statements; NB: major inductive premises need to be put first, all
   710     the rest of the goal is passed through the induction;
   711   - 'induct' proper support for mutual induction involving non-atomic
   712     rule statements (uses the new concept of simultaneous goals, see
   713     below);
   714   - append all possible rule selections, but only use the first
   715     success (no backtracking);
   716   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   717   - undeclared rule case names default to numbers 1, 2, 3, ...;
   718   - added 'print_induct_rules' (covered by help item in recent Proof
   719     General versions);
   720   - moved induct/cases attributes to Pure, methods to Provers;
   721   - generic method setup instantiated for FOL and HOL;
   722 
   723 * Pure: support multiple simultaneous goal statements, for example
   724 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   725 meta-level mechanism, this acts as if several individual goals had
   726 been stated separately; in particular common proof methods need to be
   727 repeated in order to cover all claims; note that a single elimination
   728 step is *not* sufficient to establish the two conjunctions, so this
   729 fails:
   730 
   731   assume "A & B" then have A and B ..   (*".." fails*)
   732 
   733 better use "obtain" in situations as above; alternative refer to
   734 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   735 
   736 * Pure: proper integration with ``locales''; unlike the original
   737 version by Florian Kammller, Isar locales package high-level proof
   738 contexts rather than raw logical ones (e.g. we admit to include
   739 attributes everywhere); operations on locales include merge and
   740 rename; support for implicit arguments (``structures''); simultaneous
   741 type-inference over imports and text; see also HOL/ex/Locales.thy for
   742 some examples;
   743 
   744 * Pure: the following commands have been ``localized'', supporting a
   745 target locale specification "(in name)": 'lemma', 'theorem',
   746 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   747 stored both within the locale and at the theory level (exported and
   748 qualified by the locale name);
   749 
   750 * Pure: theory goals may now be specified in ``long'' form, with
   751 ad-hoc contexts consisting of arbitrary locale elements. for example
   752 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   753 definitions may be given, too); the result is a meta-level rule with
   754 the context elements being discharged in the obvious way;
   755 
   756 * Pure: new proof command 'using' allows to augment currently used
   757 facts after a goal statement ('using' is syntactically analogous to
   758 'apply', but acts on the goal's facts only); this allows chained facts
   759 to be separated into parts given before and after a claim, as in
   760 ``from a and b have C using d and e <proof>'';
   761 
   762 * Pure: renamed "antecedent" case to "rule_context";
   763 
   764 * Pure: new 'judgment' command records explicit information about the
   765 object-logic embedding (used by several tools internally); no longer
   766 use hard-wired "Trueprop";
   767 
   768 * Pure: added 'corollary' command;
   769 
   770 * Pure: fixed 'token_translation' command;
   771 
   772 * Pure: removed obsolete 'exported' attribute;
   773 
   774 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   775 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   776 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   777 
   778 * Pure: method 'atomize' presents local goal premises as object-level
   779 statements (atomic meta-level propositions); setup controlled via
   780 rewrite rules declarations of 'atomize' attribute; example
   781 application: 'induct' method with proper rule statements in improper
   782 proof *scripts*;
   783 
   784 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   785 now consider the syntactic context of assumptions, giving a better
   786 chance to get type-inference of the arguments right (this is
   787 especially important for locales);
   788 
   789 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   790 mode;
   791 
   792 * Pure/obtain: the formal conclusion "thesis", being marked as
   793 ``internal'', may no longer be reference directly in the text;
   794 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   795 situations;
   796 
   797 * Pure: generic 'sym' attribute which declares a rule both as pure
   798 'elim?' and for the 'symmetric' operation;
   799 
   800 * Pure: marginal comments ``--'' may now occur just anywhere in the
   801 text; the fixed correlation with particular command syntax has been
   802 discontinued;
   803 
   804 * Pure: new method 'rules' is particularly well-suited for proof
   805 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   806 but often produces more compact proof terms with less detours;
   807 
   808 * Pure/Provers/classical: simplified integration with pure rule
   809 attributes and methods; the classical "intro?/elim?/dest?"
   810 declarations coincide with the pure ones; the "rule" method no longer
   811 includes classically swapped intros; "intro" and "elim" methods no
   812 longer pick rules from the context; also got rid of ML declarations
   813 AddXIs/AddXEs/AddXDs; all of this has some potential for
   814 INCOMPATIBILITY;
   815 
   816 * Provers/classical: attribute 'swapped' produces classical inversions
   817 of introduction rules;
   818 
   819 * Provers/simplifier: 'simplified' attribute may refer to explicit
   820 rules instead of full simplifier context; 'iff' attribute handles
   821 conditional rules;
   822 
   823 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   824 
   825 * HOL: 'recdef' now fails on unfinished automated proofs, use
   826 "(permissive)" option to recover old behavior;
   827 
   828 * HOL: 'inductive' no longer features separate (collective) attributes
   829 for 'intros' (was found too confusing);
   830 
   831 * HOL: properly declared induction rules less_induct and
   832 wf_induct_rule;
   833 
   834 
   835 *** HOL ***
   836 
   837 * HOL: moved over to sane numeral syntax; the new policy is as
   838 follows:
   839 
   840   - 0 and 1 are polymorphic constants, which are defined on any
   841   numeric type (nat, int, real etc.);
   842 
   843   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   844   binary representation internally;
   845 
   846   - type nat has special constructor Suc, and generally prefers Suc 0
   847   over 1::nat and Suc (Suc 0) over 2::nat;
   848 
   849 This change may cause significant problems of INCOMPATIBILITY; here
   850 are some hints on converting existing sources:
   851 
   852   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   853   entities, so expressions involving "-" (unary or binary minus) need
   854   to be spaced properly;
   855 
   856   - existing occurrences of "1" may need to be constraint "1::nat" or
   857   even replaced by Suc 0; similar for old "2";
   858 
   859   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   860 
   861   - remove all special provisions on numerals in proofs;
   862 
   863 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   864 representation (depends on bin_arith_simps in the default context);
   865 
   866 * HOL: symbolic syntax for x^2 (numeral 2);
   867 
   868 * HOL: the class of all HOL types is now called "type" rather than
   869 "term"; INCOMPATIBILITY, need to adapt references to this type class
   870 in axclass/classes, instance/arities, and (usually rare) occurrences
   871 in typings (of consts etc.); internally the class is called
   872 "HOL.type", ML programs should refer to HOLogic.typeS;
   873 
   874 * HOL/record package improvements:
   875   - new derived operations "fields" to build a partial record section,
   876     "extend" to promote a fixed record to a record scheme, and
   877     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   878     declared as simp by default;
   879   - shared operations ("more", "fields", etc.) now need to be always
   880     qualified) --- potential INCOMPATIBILITY;
   881   - removed "make_scheme" operations (use "make" with "extend") --
   882     INCOMPATIBILITY;
   883   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   884   - provides cases/induct rules for use with corresponding Isar
   885     methods (for concrete records, record schemes, concrete more
   886     parts, and schematic more parts -- in that order);
   887   - internal definitions directly based on a light-weight abstract
   888     theory of product types over typedef rather than datatype;
   889 
   890 * HOL: generic code generator for generating executable ML code from
   891 specifications; specific support for HOL constructs such as inductive
   892 datatypes and sets, as well as recursive functions; can be invoked
   893 via 'generate_code' theory section;
   894 
   895 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   896 
   897 * HOL: consolidated and renamed several theories.  In particular:
   898         Ord.thy has been absorbed into HOL.thy
   899         String.thy has been absorbed into List.thy
   900 
   901 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   902 (beware of argument permutation!);
   903 
   904 * HOL: linorder_less_split superseded by linorder_cases;
   905 
   906 * HOL/List: "nodups" renamed to "distinct";
   907 
   908 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   909 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   910   - Ex_def has changed, now need to use some_eq_ex
   911 
   912 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   913 in this (rare) case use:
   914 
   915   delSWrapper "split_all_tac"
   916   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   917 
   918 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   919 MAY FAIL;
   920 
   921 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   922 Isabelle's type classes, ^ on functions and relations has too general
   923 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   924 necessary to attach explicit type constraints;
   925 
   926 * HOL/Relation: the prefix name of the infix "O" has been changed from
   927 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   928 renamed accordingly (eg "compI" -> "rel_compI").
   929 
   930 * HOL: syntax translations now work properly with numerals and records
   931 expressions;
   932 
   933 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   934 of "lam" -- INCOMPATIBILITY;
   935 
   936 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   937 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   938 renamed "Product_Type.unit";
   939 
   940 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   941 
   942 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   943 the "cases" method);
   944 
   945 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   946 Florian Kammller);
   947 
   948 * HOL/IMP: updated and converted to new-style theory format; several
   949 parts turned into readable document, with proper Isar proof texts and
   950 some explanations (by Gerwin Klein);
   951 
   952 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   953 
   954 * HOL-Hyperreal is now a logic image;
   955 
   956 
   957 *** HOLCF ***
   958 
   959 * Isar: consts/constdefs supports mixfix syntax for continuous
   960 operations;
   961 
   962 * Isar: domain package adapted to new-style theory format, e.g. see
   963 HOLCF/ex/Dnat.thy;
   964 
   965 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   966 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   967 lift.induct_tac, always use UU instead of Undef;
   968 
   969 * HOLCF/IMP: updated and converted to new-style theory;
   970 
   971 
   972 *** ZF ***
   973 
   974 * Isar: proper integration of logic-specific tools and packages,
   975 including theory commands '(co)inductive', '(co)datatype',
   976 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   977 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   978 
   979 * theory Main no longer includes AC; for the Axiom of Choice, base
   980 your theory on Main_ZFC;
   981 
   982 * the integer library now covers quotients and remainders, with many
   983 laws relating division to addition, multiplication, etc.;
   984 
   985 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   986 typeless version of the formalism;
   987 
   988 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   989 format;
   990 
   991 * ZF/Induct: new directory for examples of inductive definitions,
   992 including theory Multiset for multiset orderings; converted to
   993 new-style theory format;
   994 
   995 * ZF: many new theorems about lists, ordinals, etc.;
   996 
   997 
   998 *** General ***
   999 
  1000 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
  1001 variable proof controls level of detail: 0 = no proofs (only oracle
  1002 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
  1003 also ref manual for further ML interfaces;
  1004 
  1005 * Pure/axclass: removed obsolete ML interface
  1006 goal_subclass/goal_arity;
  1007 
  1008 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
  1009 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
  1010 separate tokens, so expressions involving minus need to be spaced
  1011 properly;
  1012 
  1013 * Pure/syntax: support non-oriented infixes, using keyword "infix"
  1014 rather than "infixl" or "infixr";
  1015 
  1016 * Pure/syntax: concrete syntax for dummy type variables admits genuine
  1017 sort constraint specifications in type inference; e.g. "x::_::foo"
  1018 ensures that the type of "x" is of sort "foo" (but not necessarily a
  1019 type variable);
  1020 
  1021 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
  1022 control output of nested => (types); the default behavior is
  1023 "type_brackets";
  1024 
  1025 * Pure/syntax: builtin parse translation for "_constify" turns valued
  1026 tokens into AST constants;
  1027 
  1028 * Pure/syntax: prefer later declarations of translations and print
  1029 translation functions; potential INCOMPATIBILITY: need to reverse
  1030 multiple declarations for same syntax element constant;
  1031 
  1032 * Pure/show_hyps reset by default (in accordance to existing Isar
  1033 practice);
  1034 
  1035 * Provers/classical: renamed addaltern to addafter, addSaltern to
  1036 addSafter;
  1037 
  1038 * Provers/clasimp: ``iff'' declarations now handle conditional rules
  1039 as well;
  1040 
  1041 * system: tested support for MacOS X; should be able to get Isabelle +
  1042 Proof General to work in a plain Terminal after installing Poly/ML
  1043 (e.g. from the Isabelle distribution area) and GNU bash alone
  1044 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
  1045 support requires further installations, e.g. from
  1046 http://fink.sourceforge.net/);
  1047 
  1048 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
  1049 
  1050 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
  1051 of 40 MB), cf. ML_OPTIONS;
  1052 
  1053 * system: Proof General keywords specification is now part of the
  1054 Isabelle distribution (see etc/isar-keywords.el);
  1055 
  1056 * system: support for persistent Proof General sessions (refrain from
  1057 outdating all loaded theories on startup); user may create writable
  1058 logic images like this: ``isabelle -q HOL Test'';
  1059 
  1060 * system: smart selection of Isabelle process versus Isabelle
  1061 interface, accommodates case-insensitive file systems (e.g. HFS+); may
  1062 run both "isabelle" and "Isabelle" even if file names are badly
  1063 damaged (executable inspects the case of the first letter of its own
  1064 name); added separate "isabelle-process" and "isabelle-interface";
  1065 
  1066 * system: refrain from any attempt at filtering input streams; no
  1067 longer support ``8bit'' encoding of old isabelle font, instead proper
  1068 iso-latin characters may now be used; the related isatools
  1069 "symbolinput" and "nonascii" have disappeared as well;
  1070 
  1071 * system: removed old "xterm" interface (the print modes "xterm" and
  1072 "xterm_color" are still available for direct use in a suitable
  1073 terminal);
  1074 
  1075 
  1076 
  1077 New in Isabelle99-2 (February 2001)
  1078 -----------------------------------
  1079 
  1080 *** Overview of INCOMPATIBILITIES ***
  1081 
  1082 * HOL: please note that theories in the Library and elsewhere often use the
  1083 new-style (Isar) format; to refer to their theorems in an ML script you must
  1084 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
  1085 
  1086 * HOL: inductive package no longer splits induction rule aggressively,
  1087 but only as far as specified by the introductions given; the old
  1088 format may be recovered via ML function complete_split_rule or attribute
  1089 'split_rule (complete)';
  1090 
  1091 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
  1092 gfp_Tarski to gfp_unfold;
  1093 
  1094 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
  1095 
  1096 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
  1097 relation); infix "^^" has been renamed "``"; infix "``" has been
  1098 renamed "`"; "univalent" has been renamed "single_valued";
  1099 
  1100 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
  1101 operation;
  1102 
  1103 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
  1104 
  1105 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
  1106 
  1107 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
  1108 consequence, it is no longer monotonic wrt. the local goal context
  1109 (which is now passed through the inductive cases);
  1110 
  1111 * Document preparation: renamed standard symbols \<ll> to \<lless> and
  1112 \<gg> to \<ggreater>;
  1113 
  1114 
  1115 *** Document preparation ***
  1116 
  1117 * \isabellestyle{NAME} selects version of Isabelle output (currently
  1118 available: are "it" for near math-mode best-style output, "sl" for
  1119 slanted text style, and "tt" for plain type-writer; if no
  1120 \isabellestyle command is given, output is according to slanted
  1121 type-writer);
  1122 
  1123 * support sub/super scripts (for single symbols only), input syntax is
  1124 like this: "A\<^sup>*" or "A\<^sup>\<star>";
  1125 
  1126 * some more standard symbols; see Appendix A of the system manual for
  1127 the complete list of symbols defined in isabellesym.sty;
  1128 
  1129 * improved isabelle style files; more abstract symbol implementation
  1130 (should now use \isamath{...} and \isatext{...} in custom symbol
  1131 definitions);
  1132 
  1133 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
  1134 state; Note that presentation of goal states does not conform to
  1135 actual human-readable proof documents.  Please do not include goal
  1136 states into document output unless you really know what you are doing!
  1137 
  1138 * proper indentation of antiquoted output with proportional LaTeX
  1139 fonts;
  1140 
  1141 * no_document ML operator temporarily disables LaTeX document
  1142 generation;
  1143 
  1144 * isatool unsymbolize tunes sources for plain ASCII communication;
  1145 
  1146 
  1147 *** Isar ***
  1148 
  1149 * Pure: Isar now suffers initial goal statements to contain unbound
  1150 schematic variables (this does not conform to actual readable proof
  1151 documents, due to unpredictable outcome and non-compositional proof
  1152 checking); users who know what they are doing may use schematic goals
  1153 for Prolog-style synthesis of proven results;
  1154 
  1155 * Pure: assumption method (an implicit finishing) now handles actual
  1156 rules as well;
  1157 
  1158 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
  1159 initial goal, declare "that" only as Pure intro (only for single
  1160 steps); the "that" rule assumption may now be involved in implicit
  1161 finishing, thus ".." becomes a feasible for trivial obtains;
  1162 
  1163 * Pure: default proof step now includes 'intro_classes'; thus trivial
  1164 instance proofs may be performed by "..";
  1165 
  1166 * Pure: ?thesis / ?this / "..." now work for pure meta-level
  1167 statements as well;
  1168 
  1169 * Pure: more robust selection of calculational rules;
  1170 
  1171 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
  1172 rule (as well as the assumption rule);
  1173 
  1174 * Pure: 'thm_deps' command visualizes dependencies of theorems and
  1175 lemmas, using the graph browser tool;
  1176 
  1177 * Pure: predict failure of "show" in interactive mode;
  1178 
  1179 * Pure: 'thms_containing' now takes actual terms as arguments;
  1180 
  1181 * HOL: improved method 'induct' --- now handles non-atomic goals
  1182 (potential INCOMPATIBILITY); tuned error handling;
  1183 
  1184 * HOL: cases and induct rules now provide explicit hints about the
  1185 number of facts to be consumed (0 for "type" and 1 for "set" rules);
  1186 any remaining facts are inserted into the goal verbatim;
  1187 
  1188 * HOL: local contexts (aka cases) may now contain term bindings as
  1189 well; the 'cases' and 'induct' methods new provide a ?case binding for
  1190 the result to be shown in each case;
  1191 
  1192 * HOL: added 'recdef_tc' command;
  1193 
  1194 * isatool convert assists in eliminating legacy ML scripts;
  1195 
  1196 
  1197 *** HOL ***
  1198 
  1199 * HOL/Library: a collection of generic theories to be used together
  1200 with main HOL; the theory loader path already includes this directory
  1201 by default; the following existing theories have been moved here:
  1202 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
  1203 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
  1204 
  1205 * HOL/Unix: "Some aspects of Unix file-system security", a typical
  1206 modelling and verification task performed in Isabelle/HOL +
  1207 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
  1208 
  1209 * HOL/Algebra: special summation operator SUM no longer exists, it has
  1210 been replaced by setsum; infix 'assoc' now has priority 50 (like
  1211 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
  1212 'domain', this makes the theory consistent with mathematical
  1213 literature;
  1214 
  1215 * HOL basics: added overloaded operations "inverse" and "divide"
  1216 (infix "/"), syntax for generic "abs" operation, generic summation
  1217 operator \<Sum>;
  1218 
  1219 * HOL/typedef: simplified package, provide more useful rules (see also
  1220 HOL/subset.thy);
  1221 
  1222 * HOL/datatype: induction rule for arbitrarily branching datatypes is
  1223 now expressed as a proper nested rule (old-style tactic scripts may
  1224 require atomize_strip_tac to cope with non-atomic premises);
  1225 
  1226 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
  1227 to "split_conv" (old name still available for compatibility);
  1228 
  1229 * HOL: improved concrete syntax for strings (e.g. allows translation
  1230 rules with string literals);
  1231 
  1232 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
  1233  and Fleuriot's mechanization of analysis, including the transcendental
  1234  functions for the reals;
  1235 
  1236 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
  1237 
  1238 
  1239 *** CTT ***
  1240 
  1241 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
  1242 "lam" is displayed as TWO lambda-symbols
  1243 
  1244 * CTT: theory Main now available, containing everything (that is, Bool
  1245 and Arith);
  1246 
  1247 
  1248 *** General ***
  1249 
  1250 * Pure: the Simplifier has been implemented properly as a derived rule
  1251 outside of the actual kernel (at last!); the overall performance
  1252 penalty in practical applications is about 50%, while reliability of
  1253 the Isabelle inference kernel has been greatly improved;
  1254 
  1255 * print modes "brackets" and "no_brackets" control output of nested =>
  1256 (types) and ==> (props); the default behaviour is "brackets";
  1257 
  1258 * Provers: fast_tac (and friends) now handle actual object-logic rules
  1259 as assumptions as well;
  1260 
  1261 * system: support Poly/ML 4.0;
  1262 
  1263 * system: isatool install handles KDE version 1 or 2;
  1264 
  1265 
  1266 
  1267 New in Isabelle99-1 (October 2000)
  1268 ----------------------------------
  1269 
  1270 *** Overview of INCOMPATIBILITIES ***
  1271 
  1272 * HOL: simplification of natural numbers is much changed; to partly
  1273 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
  1274 issue the following ML commands:
  1275 
  1276   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
  1277   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
  1278 
  1279 * HOL: simplification no longer dives into case-expressions; this is
  1280 controlled by "t.weak_case_cong" for each datatype t;
  1281 
  1282 * HOL: nat_less_induct renamed to less_induct;
  1283 
  1284 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
  1285 fixsome to patch .thy and .ML sources automatically;
  1286 
  1287   select_equality  -> some_equality
  1288   select_eq_Ex     -> some_eq_ex
  1289   selectI2EX       -> someI2_ex
  1290   selectI2         -> someI2
  1291   selectI          -> someI
  1292   select1_equality -> some1_equality
  1293   Eps_sym_eq       -> some_sym_eq_trivial
  1294   Eps_eq           -> some_eq_trivial
  1295 
  1296 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
  1297 
  1298 * HOL: removed obsolete theorem binding expand_if (refer to split_if
  1299 instead);
  1300 
  1301 * HOL: the recursion equations generated by 'recdef' are now called
  1302 f.simps instead of f.rules;
  1303 
  1304 * HOL: qed_spec_mp now also handles bounded ALL as well;
  1305 
  1306 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  1307 sometimes be needed;
  1308 
  1309 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  1310 
  1311 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  1312 
  1313 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  1314 product is now "<*>" instead of "Times"; the lexicographic product is
  1315 now "<*lex*>" instead of "**";
  1316 
  1317 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  1318 of main HOL, but was unused); better use HOL's datatype package;
  1319 
  1320 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  1321 the old syntax may be recovered as follows:
  1322 
  1323   syntax (symbols)
  1324     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  1325       (infixl "\\<oplus>" 100)
  1326 
  1327 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1328 
  1329 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1330 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1331 internally;
  1332 
  1333 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1334 changed from A/r to A//r;
  1335 
  1336 * ZF: new treatment of arithmetic (nat & int) may break some old
  1337 proofs;
  1338 
  1339 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1340 rulify -> rule_format, elimify -> elim_format, ...);
  1341 
  1342 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1343 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1344 should have to change intro!! to intro? only); replaced "delrule" by
  1345 "rule del";
  1346 
  1347 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1348 
  1349 * Provers: strengthened force_tac by using new first_best_tac;
  1350 
  1351 * LaTeX document preparation: several changes of isabelle.sty (see
  1352 lib/texinputs);
  1353 
  1354 
  1355 *** Document preparation ***
  1356 
  1357 * formal comments (text blocks etc.) in new-style theories may now
  1358 contain antiquotations of thm/prop/term/typ/text to be presented
  1359 according to latex print mode; concrete syntax is like this:
  1360 @{term[show_types] "f(x) = a + x"};
  1361 
  1362 * isatool mkdir provides easy setup of Isabelle session directories,
  1363 including proper document sources;
  1364 
  1365 * generated LaTeX sources are now deleted after successful run
  1366 (isatool document -c); may retain a copy somewhere else via -D option
  1367 of isatool usedir;
  1368 
  1369 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1370 style files, achieving self-contained LaTeX sources and simplifying
  1371 LaTeX debugging;
  1372 
  1373 * old-style theories now produce (crude) LaTeX output as well;
  1374 
  1375 * browser info session directories are now self-contained (may be put
  1376 on WWW server seperately); improved graphs of nested sessions; removed
  1377 graph for 'all sessions';
  1378 
  1379 * several improvements in isabelle style files; \isabellestyle{it}
  1380 produces fake math mode output; \isamarkupheader is now \section by
  1381 default; see lib/texinputs/isabelle.sty etc.;
  1382 
  1383 
  1384 *** Isar ***
  1385 
  1386 * Isar/Pure: local results and corresponding term bindings are now
  1387 subject to Hindley-Milner polymorphism (similar to ML); this
  1388 accommodates incremental type-inference very nicely;
  1389 
  1390 * Isar/Pure: new derived language element 'obtain' supports
  1391 generalized existence reasoning;
  1392 
  1393 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1394 support accumulation of results, without applying any rules yet;
  1395 useful to collect intermediate results without explicit name
  1396 references, and for use with transitivity rules with more than 2
  1397 premises;
  1398 
  1399 * Isar/Pure: scalable support for case-analysis type proofs: new
  1400 'case' language element refers to local contexts symbolically, as
  1401 produced by certain proof methods; internally, case names are attached
  1402 to theorems as "tags";
  1403 
  1404 * Isar/Pure: theory command 'hide' removes declarations from
  1405 class/type/const name spaces;
  1406 
  1407 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1408 indicate potential overloading;
  1409 
  1410 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1411 
  1412 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1413 "{a,b,c}" instead of {a,b,c};
  1414 
  1415 * Isar/Pure now provides its own version of intro/elim/dest
  1416 attributes; useful for building new logics, but beware of confusion
  1417 with the version in Provers/classical;
  1418 
  1419 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1420 case name 'antecedent';
  1421 
  1422 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1423 to the current context is now done automatically);
  1424 
  1425 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1426 for definining proof methods in ML;
  1427 
  1428 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1429 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1430 most cases, one should have to change intro!! to intro? only);
  1431 replaced "delrule" by "rule del";
  1432 
  1433 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1434 'symmetric' attribute (the latter supercedes [RS sym]);
  1435 
  1436 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1437 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1438 well (including splits);
  1439 
  1440 * Isar/Provers: Simplifier and Classical methods now support all kind
  1441 of modifiers used in the past, including 'cong', 'iff', etc.
  1442 
  1443 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1444 of Simplifier and Classical reasoner);
  1445 
  1446 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1447 now support named cases; major packages (inductive, datatype, primrec,
  1448 recdef) support case names and properly name parameters;
  1449 
  1450 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1451 monotonicity conditions are extracted to be proven at end of
  1452 calculations;
  1453 
  1454 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1455 method anyway;
  1456 
  1457 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1458 split_if split_if_asm; datatype package provides theorems foo.splits =
  1459 foo.split foo.split_asm for each datatype;
  1460 
  1461 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1462 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1463 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1464 use "(cases (simplified))" method in proper proof texts);
  1465 
  1466 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1467 
  1468 * Isar: names of theorems etc. may be natural numbers as well;
  1469 
  1470 * Isar: 'pr' command: optional arguments for goals_limit and
  1471 ProofContext.prems_limit; no longer prints theory contexts, but only
  1472 proof states;
  1473 
  1474 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1475 additional print modes to be specified; e.g. "pr(latex)" will print
  1476 proof state according to the Isabelle LaTeX style;
  1477 
  1478 * Isar: improved support for emulating tactic scripts, including proof
  1479 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1480 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1481 (for HOL datatypes);
  1482 
  1483 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1484 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1485 'proof method scripts' have to be in depth-first order;
  1486 
  1487 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1488 
  1489 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1490 should instead use individual commands for printing items
  1491 (print_commands, print_methods etc.);
  1492 
  1493 * Isar: added 'nothing' --- the empty list of theorems;
  1494 
  1495 
  1496 *** HOL ***
  1497 
  1498 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1499 corresponding virtual machine and a specification of its bytecode
  1500 verifier and a lightweight bytecode verifier, including proofs of
  1501 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1502 Cornelia Pusch (see also the homepage of project Bali at
  1503 http://isabelle.in.tum.de/Bali/);
  1504 
  1505 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1506 Clemens Ballarin;
  1507 
  1508 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1509 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1510 Rasmussen;
  1511 
  1512 * HOL/Lattice: fundamental concepts of lattice theory and order
  1513 structures, including duals, properties of bounds versus algebraic
  1514 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1515 Theorem for complete lattices etc.; may also serve as a demonstration
  1516 for abstract algebraic reasoning using axiomatic type classes, and
  1517 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1518 
  1519 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1520 von Oheimb;
  1521 
  1522 * HOL/IMPP: extension of IMP with local variables and mutually
  1523 recursive procedures, by David von Oheimb;
  1524 
  1525 * HOL/Lambda: converted into new-style theory and document;
  1526 
  1527 * HOL/ex/Multiquote: example of multiple nested quotations and
  1528 anti-quotations -- basically a generalized version of de-Bruijn
  1529 representation; very useful in avoiding lifting of operations;
  1530 
  1531 * HOL/record: added general record equality rule to simpset; fixed
  1532 select-update simplification procedure to handle extended records as
  1533 well; admit "r" as field name;
  1534 
  1535 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1536 other numeric types and also as the identity of groups, rings, etc.;
  1537 
  1538 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1539 Types nat and int belong to this axclass;
  1540 
  1541 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1542    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1543    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1544   two terms #m*u and #n*u are replaced by #(m+n)*u
  1545     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1546   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1547     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1548 
  1549 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1550 powerful prover for predicate logic but knows nothing of clasets; see
  1551 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1552 
  1553 * HOL: new version of "case_tac" subsumes both boolean case split and
  1554 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1555 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1556 
  1557 * HOL: simplification no longer dives into case-expressions: only the
  1558 selector expression is simplified, but not the remaining arms; to
  1559 enable full simplification of case-expressions for datatype t, you may
  1560 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1561 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1562 
  1563 * HOL/recdef: the recursion equations generated by 'recdef' for
  1564 function 'f' are now called f.simps instead of f.rules; if all
  1565 termination conditions are proved automatically, these simplification
  1566 rules are added to the simpset, as in primrec; rules may be named
  1567 individually as well, resulting in a separate list of theorems for
  1568 each equation;
  1569 
  1570 * HOL/While is a new theory that provides a while-combinator. It
  1571 permits the definition of tail-recursive functions without the
  1572 provision of a termination measure. The latter is necessary once the
  1573 invariant proof rule for while is applied.
  1574 
  1575 * HOL: new (overloaded) notation for the set of elements below/above
  1576 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1577 
  1578 * HOL: theorems impI, allI, ballI bound as "strip";
  1579 
  1580 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1581 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1582 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1583 
  1584 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1585 
  1586 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1587 main HOL, but was unused);
  1588 
  1589 * HOL: fewer consts declared as global (e.g. have to refer to
  1590 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1591 
  1592 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1593 in case of overlap with user translations (e.g. judgements over
  1594 tuples); (note that the underlying logical represenation is still
  1595 bogus);
  1596 
  1597 
  1598 *** ZF ***
  1599 
  1600 * ZF: simplification automatically cancels common terms in arithmetic
  1601 expressions over nat and int;
  1602 
  1603 * ZF: new treatment of nat to minimize type-checking: all operators
  1604 coerce their operands to a natural number using the function natify,
  1605 making the algebraic laws unconditional;
  1606 
  1607 * ZF: as above, for int: operators coerce their operands to an integer
  1608 using the function intify;
  1609 
  1610 * ZF: the integer library now contains many of the usual laws for the
  1611 orderings, including $<=, and monotonicity laws for $+ and $*;
  1612 
  1613 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1614 simplification;
  1615 
  1616 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1617 to the simplifier and classical reasoner simultaneously;
  1618 
  1619 
  1620 *** General ***
  1621 
  1622 * Provers: blast_tac now handles actual object-logic rules as
  1623 assumptions; note that auto_tac uses blast_tac internally as well;
  1624 
  1625 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1626 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1627 
  1628 * Provers: delrules now handles destruct rules as well (no longer need
  1629 explicit make_elim);
  1630 
  1631 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1632   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1633 use instead the strong form,
  1634   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1635 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1636 from destruct-rules;
  1637 
  1638 * Provers: Simplifier.easy_setup provides a fast path to basic
  1639 Simplifier setup for new object-logics;
  1640 
  1641 * Pure: AST translation rules no longer require constant head on LHS;
  1642 
  1643 * Pure: improved name spaces: ambiguous output is qualified; support
  1644 for hiding of names;
  1645 
  1646 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1647 XSYMBOL_HOME; no longer need to do manual configuration in most
  1648 situations;
  1649 
  1650 * system: compression of ML heaps images may now be controlled via -c
  1651 option of isabelle and isatool usedir (currently only observed by
  1652 Poly/ML);
  1653 
  1654 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1655 useful for remote X11);
  1656 
  1657 * system: provide TAGS file for Isabelle sources;
  1658 
  1659 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1660 order;
  1661 
  1662 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1663 timing flag supersedes proof_timing and Toplevel.trace;
  1664 
  1665 * ML: new combinators |>> and |>>> for incremental transformations
  1666 with secondary results (e.g. certain theory extensions):
  1667 
  1668 * ML: PureThy.add_defs gets additional argument to indicate potential
  1669 overloading (usually false);
  1670 
  1671 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1672 results;
  1673 
  1674 
  1675 
  1676 New in Isabelle99 (October 1999)
  1677 --------------------------------
  1678 
  1679 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1680 
  1681 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1682 are no longer simplified.  (This allows the simplifier to unfold recursive
  1683 functional programs.)  To restore the old behaviour, declare
  1684 
  1685     Delcongs [if_weak_cong];
  1686 
  1687 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1688 complement;
  1689 
  1690 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1691 
  1692 * HOL/datatype: mutual_induct_tac no longer exists --
  1693   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1694 
  1695 * HOL/typedef: fixed type inference for representing set; type
  1696 arguments now have to occur explicitly on the rhs as type constraints;
  1697 
  1698 * ZF: The con_defs part of an inductive definition may no longer refer
  1699 to constants declared in the same theory;
  1700 
  1701 * HOL, ZF: the function mk_cases, generated by the inductive
  1702 definition package, has lost an argument.  To simplify its result, it
  1703 uses the default simpset instead of a supplied list of theorems.
  1704 
  1705 * HOL/List: the constructors of type list are now Nil and Cons;
  1706 
  1707 * Simplifier: the type of the infix ML functions
  1708         setSSolver addSSolver setSolver addSolver
  1709 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1710 for packaging solvers. A solver is created via
  1711         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1712 where the string argument is only a comment.
  1713 
  1714 
  1715 *** Proof tools ***
  1716 
  1717 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1718 decision procedure for linear arithmetic. Currently it is used for
  1719 types `nat', `int', and `real' in HOL (see below); it can, should and
  1720 will be instantiated for other types and logics as well.
  1721 
  1722 * The simplifier now accepts rewrite rules with flexible heads, eg
  1723      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1724   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1725   matching.
  1726 
  1727 
  1728 *** General ***
  1729 
  1730 * New Isabelle/Isar subsystem provides an alternative to traditional
  1731 tactical theorem proving; together with the ProofGeneral/isar user
  1732 interface it offers an interactive environment for developing human
  1733 readable proof documents (Isar == Intelligible semi-automated
  1734 reasoning); for further information see isatool doc isar-ref,
  1735 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1736 
  1737 * improved and simplified presentation of theories: better HTML markup
  1738 (including colors), graph views in several sizes; isatool usedir now
  1739 provides a proper interface for user theories (via -P option); actual
  1740 document preparation based on (PDF)LaTeX is available as well (for
  1741 new-style theories only); see isatool doc system for more information;
  1742 
  1743 * native support for Proof General, both for classic Isabelle and
  1744 Isabelle/Isar;
  1745 
  1746 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1747 using the graph browser tool;
  1748 
  1749 * Isabelle manuals now also available as PDF;
  1750 
  1751 * theory loader rewritten from scratch (may not be fully
  1752 bug-compatible); old loadpath variable has been replaced by show_path,
  1753 add_path, del_path, reset_path functions; new operations such as
  1754 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1755 isatool doc ref);
  1756 
  1757 * improved isatool install: option -k creates KDE application icon,
  1758 option -p DIR installs standalone binaries;
  1759 
  1760 * added ML_PLATFORM setting (useful for cross-platform installations);
  1761 more robust handling of platform specific ML images for SML/NJ;
  1762 
  1763 * the settings environment is now statically scoped, i.e. it is never
  1764 created again in sub-processes invoked from isabelle, isatool, or
  1765 Isabelle;
  1766 
  1767 * path element specification '~~' refers to '$ISABELLE_HOME';
  1768 
  1769 * in locales, the "assumes" and "defines" parts may be omitted if
  1770 empty;
  1771 
  1772 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1773 long arrows);
  1774 
  1775 * new print_mode "HTML";
  1776 
  1777 * new flag show_tags controls display of tags of theorems (which are
  1778 basically just comments that may be attached by some tools);
  1779 
  1780 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1781 mode and goal output format:
  1782 
  1783 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1784 244c244
  1785 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1786 ---
  1787 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1788 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1789 181c181
  1790 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1791 ---
  1792 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1793 
  1794 * function bind_thms stores lists of theorems (cf. bind_thm);
  1795 
  1796 * new shorthand tactics ftac, eatac, datac, fatac;
  1797 
  1798 * qed (and friends) now accept "" as result name; in that case the
  1799 theorem is not stored, but proper checks and presentation of the
  1800 result still apply;
  1801 
  1802 * theorem database now also indexes constants "Trueprop", "all",
  1803 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1804 
  1805 
  1806 *** HOL ***
  1807 
  1808 ** HOL arithmetic **
  1809 
  1810 * There are now decision procedures for linear arithmetic over nat and
  1811 int:
  1812 
  1813 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1814 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1815 are treated as atomic; subformulae not involving type `nat' or `int'
  1816 are ignored; quantified subformulae are ignored unless they are
  1817 positive universal or negative existential. The tactic has to be
  1818 invoked by hand and can be a little bit slow. In particular, the
  1819 running time is exponential in the number of occurrences of `min' and
  1820 `max', and `-' on `nat'.
  1821 
  1822 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1823 (negated) (in)equalities among the premises and the conclusion into
  1824 account (i.e. no compound formulae) and does not know about `min' and
  1825 `max', and `-' on `nat'. It is fast and is used automatically by the
  1826 simplifier.
  1827 
  1828 NB: At the moment, these decision procedures do not cope with mixed
  1829 nat/int formulae where the two parts interact, such as `m < n ==>
  1830 int(m) < int(n)'.
  1831 
  1832 * HOL/Numeral provides a generic theory of numerals (encoded
  1833 efficiently as bit strings); setup for types nat/int/real is in place;
  1834 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1835 int, existing theories and proof scripts may require a few additional
  1836 type constraints;
  1837 
  1838 * integer division and remainder can now be performed on constant
  1839 arguments;
  1840 
  1841 * many properties of integer multiplication, division and remainder
  1842 are now available;
  1843 
  1844 * An interface to the Stanford Validity Checker (SVC) is available through the
  1845 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1846 are proved automatically.  SVC must be installed separately, and its results
  1847 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1848 invocation of the underlying oracle).  For SVC see
  1849   http://verify.stanford.edu/SVC
  1850 
  1851 * IsaMakefile: the HOL-Real target now builds an actual image;
  1852 
  1853 
  1854 ** HOL misc **
  1855 
  1856 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1857 (in Isabelle/Isar) -- by Gertrud Bauer;
  1858 
  1859 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1860 analysis for assembly languages with subtypes;
  1861 
  1862 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1863 -- avoids syntactic ambiguities and treats state, transition, and
  1864 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1865 changed syntax and (many) tactics;
  1866 
  1867 * HOL/inductive: Now also handles more general introduction rules such
  1868   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1869   theorems are now maintained within the theory (maintained via the
  1870   "mono" attribute);
  1871 
  1872 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1873   (using function types) such as
  1874 
  1875   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1876 
  1877 * HOL/record: record_simproc (part of the default simpset) takes care
  1878 of selectors applied to updated records; record_split_tac is no longer
  1879 part of the default claset; update_defs may now be removed from the
  1880 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1881 
  1882   claset_ref () := claset() addSWrapper record_split_wrapper;
  1883   Delsimprocs [record_simproc]
  1884 
  1885 * HOL/typedef: fixed type inference for representing set; type
  1886 arguments now have to occur explicitly on the rhs as type constraints;
  1887 
  1888 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1889 names rather than an ML expression;
  1890 
  1891 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1892 supplied later.  Program schemes can be defined, such as
  1893     "While B C s = (if B s then While B C (C s) else s)"
  1894 where the well-founded relation can be chosen after B and C have been given.
  1895 
  1896 * HOL/List: the constructors of type list are now Nil and Cons;
  1897 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1898 course, ML tools referring to List.list.op # etc. have to be adapted;
  1899 
  1900 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1901 disabled by default; run isabelle with option -m HOL to get back to
  1902 the original Gordon/HOL-style output;
  1903 
  1904 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1905 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1906 
  1907 * HOL basic syntax simplified (more orthogonal): all variants of
  1908 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1909 Eps operator is provided as well: "SOME x. P[x]";
  1910 
  1911 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1912 
  1913 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1914 thus available for user theories;
  1915 
  1916 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1917 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1918 time;
  1919 
  1920 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1921 several times and then mp;
  1922 
  1923 
  1924 *** LK ***
  1925 
  1926 * the notation <<...>> is now available as a notation for sequences of
  1927 formulas;
  1928 
  1929 * the simplifier is now installed
  1930 
  1931 * the axiom system has been generalized (thanks to Soren Heilmann)
  1932 
  1933 * the classical reasoner now has a default rule database
  1934 
  1935 
  1936 *** ZF ***
  1937 
  1938 * new primrec section allows primitive recursive functions to be given
  1939 directly (as in HOL) over datatypes and the natural numbers;
  1940 
  1941 * new tactics induct_tac and exhaust_tac for induction (or case
  1942 analysis) over datatypes and the natural numbers;
  1943 
  1944 * the datatype declaration of type T now defines the recursor T_rec;
  1945 
  1946 * simplification automatically does freeness reasoning for datatype
  1947 constructors;
  1948 
  1949 * automatic type-inference, with AddTCs command to insert new
  1950 type-checking rules;
  1951 
  1952 * datatype introduction rules are now added as Safe Introduction rules
  1953 to the claset;
  1954 
  1955 * the syntax "if P then x else y" is now available in addition to
  1956 if(P,x,y);
  1957 
  1958 
  1959 *** Internal programming interfaces ***
  1960 
  1961 * tuned simplifier trace output; new flag debug_simp;
  1962 
  1963 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1964 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1965 
  1966 * AxClass.axclass_tac lost the theory argument;
  1967 
  1968 * tuned current_goals_markers semantics: begin / end goal avoids
  1969 printing empty lines;
  1970 
  1971 * removed prs and prs_fn hook, which was broken because it did not
  1972 include \n in its semantics, forcing writeln to add one
  1973 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1974 string -> unit if you really want to output text without newline;
  1975 
  1976 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1977 plain output, interface builders may have to enable 'isabelle_font'
  1978 mode to get Isabelle font glyphs as before;
  1979 
  1980 * refined token_translation interface; INCOMPATIBILITY: output length
  1981 now of type real instead of int;
  1982 
  1983 * theory loader actions may be traced via new ThyInfo.add_hook
  1984 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1985 your own database of information attached to *whole* theories -- as
  1986 opposed to intra-theory data slots offered via TheoryDataFun;
  1987 
  1988 * proper handling of dangling sort hypotheses (at last!);
  1989 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1990 extra sort hypotheses that can be witnessed from the type signature;
  1991 the force_strip_shyps flag is gone, any remaining shyps are simply
  1992 left in the theorem (with a warning issued by strip_shyps_warning);
  1993 
  1994 
  1995 
  1996 New in Isabelle98-1 (October 1998)
  1997 ----------------------------------
  1998 
  1999 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2000 
  2001 * several changes of automated proof tools;
  2002 
  2003 * HOL: major changes to the inductive and datatype packages, including
  2004 some minor incompatibilities of theory syntax;
  2005 
  2006 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  2007 called `inj_on';
  2008 
  2009 * HOL: removed duplicate thms in Arith:
  2010   less_imp_add_less  should be replaced by  trans_less_add1
  2011   le_imp_add_le      should be replaced by  trans_le_add1
  2012 
  2013 * HOL: unary minus is now overloaded (new type constraints may be
  2014 required);
  2015 
  2016 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  2017 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  2018 now taken as an integer constant.
  2019 
  2020 * Pure: ML function 'theory_of' renamed to 'theory';
  2021 
  2022 
  2023 *** Proof tools ***
  2024 
  2025 * Simplifier:
  2026   1. Asm_full_simp_tac is now more aggressive.
  2027      1. It will sometimes reorient premises if that increases their power to
  2028         simplify.
  2029      2. It does no longer proceed strictly from left to right but may also
  2030         rotate premises to achieve further simplification.
  2031      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  2032      old Asm_full_simp_tac in that it does not rotate premises.
  2033   2. The simplifier now knows a little bit about nat-arithmetic.
  2034 
  2035 * Classical reasoner: wrapper mechanism for the classical reasoner now
  2036 allows for selected deletion of wrappers, by introduction of names for
  2037 wrapper functionals.  This implies that addbefore, addSbefore,
  2038 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  2039 and that adding two tactics with the same name overwrites the first
  2040 one (emitting a warning).
  2041   type wrapper = (int -> tactic) -> (int -> tactic)
  2042   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  2043   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  2044   delWrapper, delSWrapper: claset *  string            -> claset
  2045   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  2046 
  2047 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  2048 semantics; addbefore now affects only the unsafe part of step_tac
  2049 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  2050 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  2051 by Force_tac;
  2052 
  2053 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  2054 compWrapper; added safe wrapper (and access functions for it);
  2055 
  2056 * HOL/split_all_tac is now much faster and fails if there is nothing
  2057 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  2058 and the names of the automatically generated variables have changed.
  2059 split_all_tac has moved within claset() from unsafe wrappers to safe
  2060 wrappers, which means that !!-bound variables are split much more
  2061 aggressively, and safe_tac and clarify_tac now split such variables.
  2062 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  2063 Note: the same holds for record_split_tac, which does the job of
  2064 split_all_tac for record fields.
  2065 
  2066 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  2067 permanently to the default simpset using Addsplits just like
  2068 Addsimps. They can be removed via Delsplits just like
  2069 Delsimps. Lower-case versions are also available.
  2070 
  2071 * HOL/Simplifier: The rule split_if is now part of the default
  2072 simpset. This means that the simplifier will eliminate all occurrences
  2073 of if-then-else in the conclusion of a goal. To prevent this, you can
  2074 either remove split_if completely from the default simpset by
  2075 `Delsplits [split_if]' or remove it in a specific call of the
  2076 simplifier using `... delsplits [split_if]'.  You can also add/delete
  2077 other case splitting rules to/from the default simpset: every datatype
  2078 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  2079 t is the name of the datatype).
  2080 
  2081 * Classical reasoner / Simplifier combination: new force_tac (and
  2082 derivatives Force_tac, force) combines rewriting and classical
  2083 reasoning (and whatever other tools) similarly to auto_tac, but is
  2084 aimed to solve the given subgoal completely.
  2085 
  2086 
  2087 *** General ***
  2088 
  2089 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  2090 and `goalw': the theory is no longer needed as an explicit argument -
  2091 the current theory context is used; assumptions are no longer returned
  2092 at the ML-level unless one of them starts with ==> or !!; it is
  2093 recommended to convert to these new commands using isatool fixgoal
  2094 (backup your sources first!);
  2095 
  2096 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  2097 the current theory context, and 'theory' to lookup stored theories;
  2098 
  2099 * new theory section 'locale' for declaring constants, assumptions and
  2100 definitions that have local scope;
  2101 
  2102 * new theory section 'nonterminals' for purely syntactic types;
  2103 
  2104 * new theory section 'setup' for generic ML setup functions
  2105 (e.g. package initialization);
  2106 
  2107 * the distribution now includes Isabelle icons: see
  2108 lib/logo/isabelle-{small,tiny}.xpm;
  2109 
  2110 * isatool install - install binaries with absolute references to
  2111 ISABELLE_HOME/bin;
  2112 
  2113 * isatool logo -- create instances of the Isabelle logo (as EPS);
  2114 
  2115 * print mode 'emacs' reserved for Isamode;
  2116 
  2117 * support multiple print (ast) translations per constant name;
  2118 
  2119 * theorems involving oracles are now printed with a suffixed [!];
  2120 
  2121 
  2122 *** HOL ***
  2123 
  2124 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  2125 
  2126 * HOL/inductive package reorganized and improved: now supports mutual
  2127 definitions such as
  2128 
  2129   inductive EVEN ODD
  2130     intrs
  2131       null "0 : EVEN"
  2132       oddI "n : EVEN ==> Suc n : ODD"
  2133       evenI "n : ODD ==> Suc n : EVEN"
  2134 
  2135 new theorem list "elims" contains an elimination rule for each of the
  2136 recursive sets; inductive definitions now handle disjunctive premises
  2137 correctly (also ZF);
  2138 
  2139 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  2140 "mutual_induct" no longer exists - the induction rule is always
  2141 contained in "induct";
  2142 
  2143 
  2144 * HOL/datatype package re-implemented and greatly improved: now
  2145 supports mutually recursive datatypes such as
  2146 
  2147   datatype
  2148     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  2149             | SUM ('a aexp) ('a aexp)
  2150             | DIFF ('a aexp) ('a aexp)
  2151             | NUM 'a
  2152   and
  2153     'a bexp = LESS ('a aexp) ('a aexp)
  2154             | AND ('a bexp) ('a bexp)
  2155             | OR ('a bexp) ('a bexp)
  2156 
  2157 as well as indirectly recursive datatypes such as
  2158 
  2159   datatype
  2160     ('a, 'b) term = Var 'a
  2161                   | App 'b ((('a, 'b) term) list)
  2162 
  2163 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  2164 induction on mutually / indirectly recursive datatypes.
  2165 
  2166 Primrec equations are now stored in theory and can be accessed via
  2167 <function_name>.simps.
  2168 
  2169 INCOMPATIBILITIES:
  2170 
  2171   - Theories using datatypes must now have theory Datatype as an
  2172     ancestor.
  2173   - The specific <typename>.induct_tac no longer exists - use the
  2174     generic induct_tac instead.
  2175   - natE has been renamed to nat.exhaust - use exhaust_tac
  2176     instead of res_inst_tac ... natE. Note that the variable
  2177     names in nat.exhaust differ from the names in natE, this
  2178     may cause some "fragile" proofs to fail.
  2179   - The theorems split_<typename>_case and split_<typename>_case_asm
  2180     have been renamed to <typename>.split and <typename>.split_asm.
  2181   - Since default sorts of type variables are now handled correctly,
  2182     some datatype definitions may have to be annotated with explicit
  2183     sort constraints.
  2184   - Primrec definitions no longer require function name and type
  2185     of recursive argument.
  2186 
  2187 Consider using isatool fixdatatype to adapt your theories and proof
  2188 scripts to the new package (backup your sources first!).
  2189 
  2190 
  2191 * HOL/record package: considerably improved implementation; now
  2192 includes concrete syntax for record types, terms, updates; theorems
  2193 for surjective pairing and splitting !!-bound record variables; proof
  2194 support is as follows:
  2195 
  2196   1) standard conversions (selectors or updates applied to record
  2197 constructor terms) are part of the standard simpset;
  2198 
  2199   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  2200 made part of standard simpset and claset via addIffs;
  2201 
  2202   3) a tactic for record field splitting (record_split_tac) is part of
  2203 the standard claset (addSWrapper);
  2204 
  2205 To get a better idea about these rules you may retrieve them via
  2206 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  2207 the name of your record type.
  2208 
  2209 The split tactic 3) conceptually simplifies by the following rule:
  2210 
  2211   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  2212 
  2213 Thus any record variable that is bound by meta-all will automatically
  2214 blow up into some record constructor term, consequently the
  2215 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  2216 solve record problems automatically.
  2217 
  2218 
  2219 * reorganized the main HOL image: HOL/Integ and String loaded by
  2220 default; theory Main includes everything;
  2221 
  2222 * automatic simplification of integer sums and comparisons, using cancellation;
  2223 
  2224 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  2225 
  2226 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  2227 
  2228 * many new identities for unions, intersections, set difference, etc.;
  2229 
  2230 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  2231 called split_if, split_split, split_sum_case and split_nat_case (to go
  2232 with add/delsplits);
  2233 
  2234 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  2235 (?x::unit) = (); this is made part of the default simpset, which COULD
  2236 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  2237 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  2238 unit_abs_eta_conv is added in order to counter the effect of
  2239 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  2240 %u.f();
  2241 
  2242 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  2243 makes more sense);
  2244 
  2245 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2246   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2247   disjointness reasoning but breaking a few old proofs.
  2248 
  2249 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  2250 to 'converse' from 'inverse' (for compatibility with ZF and some
  2251 literature);
  2252 
  2253 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  2254 the well-founded relation;
  2255 
  2256 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  2257     Compl A.  The "Compl" syntax remains available as input syntax for this
  2258     release ONLY.
  2259 
  2260 * HOL/Update: new theory of function updates:
  2261     f(a:=b) == %x. if x=a then b else f x
  2262 may also be iterated as in f(a:=b,c:=d,...);
  2263 
  2264 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  2265 
  2266 * HOL/List:
  2267   - new function list_update written xs[i:=v] that updates the i-th
  2268     list position. May also be iterated as in xs[i:=a,j:=b,...].
  2269   - new function `upt' written [i..j(] which generates the list
  2270     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  2271     bound write [i..j], which is a shorthand for [i..j+1(].
  2272   - new lexicographic orderings and corresponding wellfoundedness theorems.
  2273 
  2274 * HOL/Arith:
  2275   - removed 'pred' (predecessor) function;
  2276   - generalized some theorems about n-1;
  2277   - many new laws about "div" and "mod";
  2278   - new laws about greatest common divisors (see theory ex/Primes);
  2279 
  2280 * HOL/Relation: renamed the relational operator r^-1 "converse"
  2281 instead of "inverse";
  2282 
  2283 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  2284   of the multiset ordering;
  2285 
  2286 * directory HOL/Real: a construction of the reals using Dedekind cuts
  2287   (not included by default);
  2288 
  2289 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  2290 
  2291 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  2292   programs, i.e. different program variables may have different types.
  2293 
  2294 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2295   [previously, this check worked only if the rewrite rule was unconditional]
  2296   Now rew can involve either definitions or equalities (either == or =).
  2297 
  2298 
  2299 *** ZF ***
  2300 
  2301 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  2302   only the theorems proved on ZF.ML;
  2303 
  2304 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2305   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2306   disjointness reasoning but breaking a few old proofs.
  2307 
  2308 * ZF/Update: new theory of function updates
  2309     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  2310   may also be iterated as in f(a:=b,c:=d,...);
  2311 
  2312 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  2313 
  2314 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2315   [previously, this check worked only if the rewrite rule was unconditional]
  2316   Now rew can involve either definitions or equalities (either == or =).
  2317 
  2318 * case_tac provided for compatibility with HOL
  2319     (like the old excluded_middle_tac, but with subgoals swapped)
  2320 
  2321 
  2322 *** Internal programming interfaces ***
  2323 
  2324 * Pure: several new basic modules made available for general use, see
  2325 also src/Pure/README;
  2326 
  2327 * improved the theory data mechanism to support encapsulation (data
  2328 kind name replaced by private Object.kind, acting as authorization
  2329 key); new type-safe user interface via functor TheoryDataFun; generic
  2330 print_data function becomes basically useless;
  2331 
  2332 * removed global_names compatibility flag -- all theory declarations
  2333 are qualified by default;
  2334 
  2335 * module Pure/Syntax now offers quote / antiquote translation
  2336 functions (useful for Hoare logic etc. with implicit dependencies);
  2337 see HOL/ex/Antiquote for an example use;
  2338 
  2339 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2340 cterm -> thm;
  2341 
  2342 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2343 subgoal;
  2344 
  2345 * Display.print_goals function moved to Locale.print_goals;
  2346 
  2347 * standard print function for goals supports current_goals_markers
  2348 variable for marking begin of proof, end of proof, start of goal; the
  2349 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2350 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2351 for example;
  2352 
  2353 
  2354 
  2355 New in Isabelle98 (January 1998)
  2356 --------------------------------
  2357 
  2358 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2359 
  2360 * changed lexical syntax of terms / types: dots made part of long
  2361 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2362 
  2363 * simpset (and claset) reference variable replaced by functions
  2364 simpset / simpset_ref;
  2365 
  2366 * no longer supports theory aliases (via merge) and non-trivial
  2367 implicit merge of thms' signatures;
  2368 
  2369 * most internal names of constants changed due to qualified names;
  2370 
  2371 * changed Pure/Sequence interface (see Pure/seq.ML);
  2372 
  2373 
  2374 *** General Changes ***
  2375 
  2376 * hierachically structured name spaces (for consts, types, axms, thms
  2377 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2378 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2379 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2380 long_names for fully qualified output names; NOTE: ML programs
  2381 (special tactics, packages etc.) referring to internal names may have
  2382 to be adapted to cope with fully qualified names; in case of severe
  2383 backward campatibility problems try setting 'global_names' at compile
  2384 time to have enrything declared within a flat name space; one may also
  2385 fine tune name declarations in theories via the 'global' and 'local'
  2386 section;
  2387 
  2388 * reimplemented the implicit simpset and claset using the new anytype
  2389 data filed in signatures; references simpset:simpset ref etc. are
  2390 replaced by functions simpset:unit->simpset and
  2391 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2392 to patch your ML files accordingly;
  2393 
  2394 * HTML output now includes theory graph data for display with Java
  2395 applet or isatool browser; data generated automatically via isatool
  2396 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2397 
  2398 * defs may now be conditional; improved rewrite_goals_tac to handle
  2399 conditional equations;
  2400 
  2401 * defs now admits additional type arguments, using TYPE('a) syntax;
  2402 
  2403 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2404 creates a new theory node; implicit merge of thms' signatures is
  2405 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2406 transfer:theory->thm->thm in (rare) cases;
  2407 
  2408 * improved handling of draft signatures / theories; draft thms (and
  2409 ctyps, cterms) are automatically promoted to real ones;
  2410 
  2411 * slightly changed interfaces for oracles: admit many per theory, named
  2412 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2413 
  2414 * print_goals: optional output of const types (set show_consts and
  2415 show_types);
  2416 
  2417 * improved output of warnings (###) and errors (***);
  2418 
  2419 * subgoal_tac displays a warning if the new subgoal has type variables;
  2420 
  2421 * removed old README and Makefiles;
  2422 
  2423 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2424 
  2425 * removed obsolete init_pps and init_database;
  2426 
  2427 * deleted the obsolete tactical STATE, which was declared by
  2428     fun STATE tacfun st = tacfun st st;
  2429 
  2430 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2431 (which abbreviates $HOME);
  2432 
  2433 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2434 use isatool fixseq to adapt your ML programs (this works for fully
  2435 qualified references to the Sequence structure only!);
  2436 
  2437 * use_thy no longer requires writable current directory; it always
  2438 reloads .ML *and* .thy file, if either one is out of date;
  2439 
  2440 
  2441 *** Classical Reasoner ***
  2442 
  2443 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2444 tactics that use classical reasoning to simplify a subgoal without
  2445 splitting it into several subgoals;
  2446 
  2447 * Safe_tac: like safe_tac but uses the default claset;
  2448 
  2449 
  2450 *** Simplifier ***
  2451 
  2452 * added simplification meta rules:
  2453     (asm_)(full_)simplify: simpset -> thm -> thm;
  2454 
  2455 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2456 logics (again);
  2457 
  2458 * added prems argument to simplification procedures;
  2459 
  2460 * HOL, FOL, ZF: added infix function `addsplits':
  2461   instead of `<simpset> setloop (split_tac <thms>)'
  2462   you can simply write `<simpset> addsplits <thms>'
  2463 
  2464 
  2465 *** Syntax ***
  2466 
  2467 * TYPE('a) syntax for type reflection terms;
  2468 
  2469 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2470 
  2471 * pretty printer: changed order of mixfix annotation preference (again!);
  2472 
  2473 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2474 
  2475 
  2476 *** HOL ***
  2477 
  2478 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2479   with `addloop' of the simplifier to faciliate case splitting in premises.
  2480 
  2481 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2482 
  2483 * HOL/Auth: new protocol proofs including some for the Internet
  2484   protocol TLS;
  2485 
  2486 * HOL/Map: new theory of `maps' a la VDM;
  2487 
  2488 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2489 cancelling out common nat summands from =, <, <= (in)equalities, or
  2490 differences; simplification procedures nat_cancel_factor for
  2491 cancelling common factor from =, <, <= (in)equalities over natural
  2492 sums; nat_cancel contains both kinds of procedures, it is installed by
  2493 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2494 
  2495 * HOL/simplifier: terms of the form
  2496   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2497   are rewritten to
  2498   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2499   and those of the form
  2500   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2501   are rewritten to
  2502   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2503 
  2504 * HOL/datatype
  2505   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2506 
  2507   P(t_case f1 ... fn x) =
  2508      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2509         ...
  2510        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2511      )
  2512 
  2513   and a theorem `split_t_case_asm' of the form
  2514 
  2515   P(t_case f1 ... fn x) =
  2516     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2517         ...
  2518        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2519      )
  2520   which can be added to a simpset via `addsplits'. The existing theorems
  2521   expand_list_case and expand_option_case have been renamed to
  2522   split_list_case and split_option_case.
  2523 
  2524 * HOL/Arithmetic:
  2525   - `pred n' is automatically converted to `n-1'.
  2526     Users are strongly encouraged not to use `pred' any longer,
  2527     because it will disappear altogether at some point.
  2528   - Users are strongly encouraged to write "0 < n" rather than
  2529     "n ~= 0". Theorems and proof tools have been modified towards this
  2530     `standard'.
  2531 
  2532 * HOL/Lists:
  2533   the function "set_of_list" has been renamed "set" (and its theorems too);
  2534   the function "nth" now takes its arguments in the reverse order and
  2535   has acquired the infix notation "!" as in "xs!n".
  2536 
  2537 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2538 
  2539 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2540   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2541 
  2542 * HOL/record: extensible records with schematic structural subtyping
  2543 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2544 still lacks various theorems and concrete record syntax;
  2545 
  2546 
  2547 *** HOLCF ***
  2548 
  2549 * removed "axioms" and "generated by" sections;
  2550 
  2551 * replaced "ops" section by extended "consts" section, which is capable of
  2552   handling the continuous function space "->" directly;
  2553 
  2554 * domain package:
  2555   . proves theorems immediately and stores them in the theory,
  2556   . creates hierachical name space,
  2557   . now uses normal mixfix annotations (instead of cinfix...),
  2558   . minor changes to some names and values (for consistency),
  2559   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2560   . separator between mutual domain defs: changed "," to "and",
  2561   . improved handling of sort constraints;  now they have to
  2562     appear on the left-hand side of the equations only;
  2563 
  2564 * fixed LAM <x,y,zs>.b syntax;
  2565 
  2566 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2567 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2568 
  2569 
  2570 *** FOL and ZF ***
  2571 
  2572 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2573   with `addloop' of the simplifier to faciliate case splitting in premises.
  2574 
  2575 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2576 in HOL, they strip ALL and --> from proved theorems;
  2577 
  2578 
  2579 
  2580 New in Isabelle94-8 (May 1997)
  2581 ------------------------------
  2582 
  2583 *** General Changes ***
  2584 
  2585 * new utilities to build / run / maintain Isabelle etc. (in parts
  2586 still somewhat experimental); old Makefiles etc. still functional;
  2587 
  2588 * new 'Isabelle System Manual';
  2589 
  2590 * INSTALL text, together with ./configure and ./build scripts;
  2591 
  2592 * reimplemented type inference for greater efficiency, better error
  2593 messages and clean internal interface;
  2594 
  2595 * prlim command for dealing with lots of subgoals (an easier way of
  2596 setting goals_limit);
  2597 
  2598 
  2599 *** Syntax ***
  2600 
  2601 * supports alternative (named) syntax tables (parser and pretty
  2602 printer); internal interface is provided by add_modesyntax(_i);
  2603 
  2604 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2605 be used in conjunction with the Isabelle symbol font; uses the
  2606 "symbols" syntax table;
  2607 
  2608 * added token_translation interface (may translate name tokens in
  2609 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2610 the current print_mode); IMPORTANT: user print translation functions
  2611 are responsible for marking newly introduced bounds
  2612 (Syntax.mark_boundT);
  2613 
  2614 * token translations for modes "xterm" and "xterm_color" that display
  2615 names in bold, underline etc. or colors (which requires a color
  2616 version of xterm);
  2617 
  2618 * infixes may now be declared with names independent of their syntax;
  2619 
  2620 * added typed_print_translation (like print_translation, but may
  2621 access type of constant);
  2622 
  2623 
  2624 *** Classical Reasoner ***
  2625 
  2626 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2627 some limitations.  Blast_tac...
  2628   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2629   + ignores elimination rules that don't have the correct format
  2630         (the conclusion MUST be a formula variable)
  2631   + ignores types, which can make HOL proofs fail
  2632   + rules must not require higher-order unification, e.g. apply_type in ZF
  2633     [message "Function Var's argument not a bound variable" relates to this]
  2634   + its proof strategy is more general but can actually be slower
  2635 
  2636 * substitution with equality assumptions no longer permutes other
  2637 assumptions;
  2638 
  2639 * minor changes in semantics of addafter (now called addaltern); renamed
  2640 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2641 (and access functions for it);
  2642 
  2643 * improved combination of classical reasoner and simplifier:
  2644   + functions for handling clasimpsets
  2645   + improvement of addss: now the simplifier is called _after_ the
  2646     safe steps.
  2647   + safe variant of addss called addSss: uses safe simplifications
  2648     _during_ the safe steps. It is more complete as it allows multiple
  2649     instantiations of unknowns (e.g. with slow_tac).
  2650 
  2651 *** Simplifier ***
  2652 
  2653 * added interface for simplification procedures (functions that
  2654 produce *proven* rewrite rules on the fly, depending on current
  2655 redex);
  2656 
  2657 * ordering on terms as parameter (used for ordered rewriting);
  2658 
  2659 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2660 
  2661 * the solver is now split into a safe and an unsafe part.
  2662 This should be invisible for the normal user, except that the
  2663 functions setsolver and addsolver have been renamed to setSolver and
  2664 addSolver; added safe_asm_full_simp_tac;
  2665 
  2666 
  2667 *** HOL ***
  2668 
  2669 * a generic induction tactic `induct_tac' which works for all datatypes and
  2670 also for type `nat';
  2671 
  2672 * a generic case distinction tactic `exhaust_tac' which works for all
  2673 datatypes and also for type `nat';
  2674 
  2675 * each datatype comes with a function `size';
  2676 
  2677 * patterns in case expressions allow tuple patterns as arguments to
  2678 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2679 
  2680 * primrec now also works with type nat;
  2681 
  2682 * recdef: a new declaration form, allows general recursive functions to be
  2683 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2684 
  2685 * the constant for negation has been renamed from "not" to "Not" to
  2686 harmonize with FOL, ZF, LK, etc.;
  2687 
  2688 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2689 infinite lists;
  2690 
  2691 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2692 
  2693 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2694 problems in commutative rings, using axiomatic type classes for + and *;
  2695 
  2696 * more examples in HOL/MiniML and HOL/Auth;
  2697 
  2698 * more default rewrite rules for quantifiers, union/intersection;
  2699 
  2700 * a new constant `arbitrary == @x.False';
  2701 
  2702 * HOLCF/IOA replaces old HOL/IOA;
  2703 
  2704 * HOLCF changes: derived all rules and arities
  2705   + axiomatic type classes instead of classes
  2706   + typedef instead of faking type definitions
  2707   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2708   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2709   + eliminated the types void, one, tr
  2710   + use unit lift and bool lift (with translations) instead of one and tr
  2711   + eliminated blift from Lift3.thy (use Def instead of blift)
  2712   all eliminated rules are derived as theorems --> no visible changes ;
  2713 
  2714 
  2715 *** ZF ***
  2716 
  2717 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2718 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2719 as ZF_cs addSIs [equalityI];
  2720 
  2721 
  2722 
  2723 New in Isabelle94-7 (November 96)
  2724 ---------------------------------
  2725 
  2726 * allowing negative levels (as offsets) in prlev and choplev;
  2727 
  2728 * super-linear speedup for large simplifications;
  2729 
  2730 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2731 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2732 FAIL); can suppress it using the command Delsimps (ex_simps @
  2733 all_simps); De Morgan laws are also now included, by default;
  2734 
  2735 * improved printing of ==>  :  ~:
  2736 
  2737 * new object-logic "Sequents" adds linear logic, while replacing LK
  2738 and Modal (thanks to Sara Kalvala);
  2739 
  2740 * HOL/Auth: correctness proofs for authentication protocols;
  2741 
  2742 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2743 examples on HOL/Auth);
  2744 
  2745 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2746 the rewriter and classical reasoner simultaneously;
  2747 
  2748 * function uresult no longer returns theorems in "standard" format;
  2749 regain previous version by: val uresult = standard o uresult;
  2750 
  2751 
  2752 
  2753 New in Isabelle94-6
  2754 -------------------
  2755 
  2756 * oracles -- these establish an interface between Isabelle and trusted
  2757 external reasoners, which may deliver results as theorems;
  2758 
  2759 * proof objects (in particular record all uses of oracles);
  2760 
  2761 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2762 
  2763 * "constdefs" section in theory files;
  2764 
  2765 * "primrec" section (HOL) no longer requires names;
  2766 
  2767 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2768 
  2769 
  2770 
  2771 New in Isabelle94-5
  2772 -------------------
  2773 
  2774 * reduced space requirements;
  2775 
  2776 * automatic HTML generation from theories;
  2777 
  2778 * theory files no longer require "..." (quotes) around most types;
  2779 
  2780 * new examples, including two proofs of the Church-Rosser theorem;
  2781 
  2782 * non-curried (1994) version of HOL is no longer distributed;
  2783 
  2784 
  2785 
  2786 New in Isabelle94-4
  2787 -------------------
  2788 
  2789 * greatly reduced space requirements;
  2790 
  2791 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2792 
  2793 * searchable theorem database (see the section "Retrieving theorems" on
  2794 page 8 of the Reference Manual);
  2795 
  2796 * new examples, including Grabczewski's monumental case study of the
  2797 Axiom of Choice;
  2798 
  2799 * The previous version of HOL renamed to Old_HOL;
  2800 
  2801 * The new version of HOL (previously called CHOL) uses a curried syntax
  2802 for functions.  Application looks like f a b instead of f(a,b);
  2803 
  2804 * Mutually recursive inductive definitions finally work in HOL;
  2805 
  2806 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2807 translates to the operator "split";
  2808 
  2809 
  2810 
  2811 New in Isabelle94-3
  2812 -------------------
  2813 
  2814 * new infix operator, addss, allowing the classical reasoner to
  2815 perform simplification at each step of its search.  Example:
  2816         fast_tac (cs addss ss)
  2817 
  2818 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2819 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2820 look like (a,b) instead of <a,b>;
  2821 
  2822 * PLEASE NOTE: CHOL will eventually replace HOL!
  2823 
  2824 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2825 It translates to the operator "split".  A new theory of integers is available;
  2826 
  2827 * In ZF, integer numerals now denote two's-complement binary integers.
  2828 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2829 
  2830 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2831 of the Axiom of Choice;
  2832 
  2833 
  2834 
  2835 New in Isabelle94-2
  2836 -------------------
  2837 
  2838 * Significantly faster resolution;
  2839 
  2840 * the different sections in a .thy file can now be mixed and repeated
  2841 freely;
  2842 
  2843 * Database of theorems for FOL, HOL and ZF.  New
  2844 commands including qed, qed_goal and bind_thm store theorems in the database.
  2845 
  2846 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2847 a given theory (thms_of), or find out what theory a theorem was proved in
  2848 (theory_of_thm);
  2849 
  2850 * Bugs fixed in the inductive definition and datatype packages;
  2851 
  2852 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2853 and HOL_dup_cs obsolete;
  2854 
  2855 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2856 have been removed;
  2857 
  2858 * Simpler definition of function space in ZF;
  2859 
  2860 * new results about cardinal and ordinal arithmetic in ZF;
  2861 
  2862 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2863 types;
  2864 
  2865 
  2866 $Id$