NEWS
author wenzelm
Tue Aug 06 11:19:00 2002 +0200 (2002-08-06)
changeset 13459 83f41b047a39
parent 13443 1c3327c348b3
child 13463 07747943c626
permissions -rw-r--r--
* Pure: predefined locales "var" and "struct" are useful for sharing
parameters (as in CASL, for example); just specify something like
``var x + var y + struct M'' as import;
     1 
     2 Isabelle NEWS -- history user-relevant changes
     3 ==============================================
     4 
     5 New in this Isabelle release
     6 ----------------------------
     7 
     8 *** General ***
     9 
    10 * Pure: locale specifications now produce predicate definitions
    11 according to the body of text (covering assumptions modulo local
    12 definitions); predicate "loc_axioms" covers newly introduced text,
    13 while "loc" is cumulative wrt. all included locale expressions; the
    14 latter view is presented only on export into the global theory
    15 context; potential INCOMPATIBILITY, use "(open)" option to fall back
    16 on the old view without predicates;
    17 
    18 * Pure: predefined locales "var" and "struct" are useful for sharing
    19 parameters (as in CASL, for example); just specify something like
    20 ``var x + var y + struct M'' as import;
    21 
    22 * improved induct method: assumptions introduced by case "foo" are
    23 split into "foo.hyps" (from the rule) and "foo.prems" (from the goal
    24 statement); "foo" still refers to all facts collectively;
    25 
    26 * improved thms_containing: proper indexing of facts instead of raw
    27 theorems; check validity of results wrt. current name space; include
    28 local facts of proof configuration (also covers active locales); an
    29 optional limit for the number of printed facts may be given (the
    30 default is 40);
    31 
    32 
    33 *** HOL ***
    34 
    35 * 'typedef' command has new option "open" to suppress the set
    36 definition;
    37 
    38 * attribute [symmetric] now works for relations as well; it turns
    39 (x,y) : R^-1 into (y,x) : R, and vice versa;
    40 
    41 * arith(_tac) does now know about div k and mod k where k is a numeral
    42 of type nat or int. It can solve simple goals like
    43 
    44   "0 < n ==> n div 2 < (n::nat)"
    45 
    46 but fails if divisibility plays a role like in
    47 
    48   "n div 2 + (n+1) div 2 = (n::nat)"
    49 
    50 * simp's arithmetic capabilities have been enhanced a bit: it now
    51 takes ~= in premises into account (by performing a case split);
    52 
    53 
    54 
    55 New in Isabelle2002 (March 2002)
    56 --------------------------------
    57 
    58 *** Document preparation ***
    59 
    60 * greatly simplified document preparation setup, including more
    61 graceful interpretation of isatool usedir -i/-d/-D options, and more
    62 instructive isatool mkdir; users should basically be able to get
    63 started with "isatool mkdir HOL Test && isatool make"; alternatively,
    64 users may run a separate document processing stage manually like this:
    65 "isatool usedir -D output HOL Test && isatool document Test/output";
    66 
    67 * theory dependency graph may now be incorporated into documents;
    68 isatool usedir -g true will produce session_graph.eps/.pdf for use
    69 with \includegraphics of LaTeX;
    70 
    71 * proper spacing of consecutive markup elements, especially text
    72 blocks after section headings;
    73 
    74 * support bold style (for single symbols only), input syntax is like
    75 this: "\<^bold>\<alpha>" or "\<^bold>A";
    76 
    77 * \<bullet> is now output as bold \cdot by default, which looks much
    78 better in printed text;
    79 
    80 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
    81 note that these symbols are currently unavailable in Proof General /
    82 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
    83 
    84 * isatool latex no longer depends on changed TEXINPUTS, instead
    85 isatool document copies the Isabelle style files to the target
    86 location;
    87 
    88 
    89 *** Isar ***
    90 
    91 * Pure/Provers: improved proof by cases and induction;
    92   - 'case' command admits impromptu naming of parameters (such as
    93     "case (Suc n)");
    94   - 'induct' method divinates rule instantiation from the inductive
    95     claim; no longer requires excessive ?P bindings for proper
    96     instantiation of cases;
    97   - 'induct' method properly enumerates all possibilities of set/type
    98     rules; as a consequence facts may be also passed through *type*
    99     rules without further ado;
   100   - 'induct' method now derives symbolic cases from the *rulified*
   101     rule (before it used to rulify cases stemming from the internal
   102     atomized version); this means that the context of a non-atomic
   103     statement becomes is included in the hypothesis, avoiding the
   104     slightly cumbersome show "PROP ?case" form;
   105   - 'induct' may now use elim-style induction rules without chaining
   106     facts, using ``missing'' premises from the goal state; this allows
   107     rules stemming from inductive sets to be applied in unstructured
   108     scripts, while still benefitting from proper handling of non-atomic
   109     statements; NB: major inductive premises need to be put first, all
   110     the rest of the goal is passed through the induction;
   111   - 'induct' proper support for mutual induction involving non-atomic
   112     rule statements (uses the new concept of simultaneous goals, see
   113     below);
   114   - append all possible rule selections, but only use the first
   115     success (no backtracking);
   116   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   117   - undeclared rule case names default to numbers 1, 2, 3, ...;
   118   - added 'print_induct_rules' (covered by help item in recent Proof
   119     General versions);
   120   - moved induct/cases attributes to Pure, methods to Provers;
   121   - generic method setup instantiated for FOL and HOL;
   122 
   123 * Pure: support multiple simultaneous goal statements, for example
   124 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   125 meta-level mechanism, this acts as if several individual goals had
   126 been stated separately; in particular common proof methods need to be
   127 repeated in order to cover all claims; note that a single elimination
   128 step is *not* sufficient to establish the two conjunctions, so this
   129 fails:
   130 
   131   assume "A & B" then have A and B ..   (*".." fails*)
   132 
   133 better use "obtain" in situations as above; alternative refer to
   134 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   135 
   136 * Pure: proper integration with ``locales''; unlike the original
   137 version by Florian Kammüller, Isar locales package high-level proof
   138 contexts rather than raw logical ones (e.g. we admit to include
   139 attributes everywhere); operations on locales include merge and
   140 rename; support for implicit arguments (``structures''); simultaneous
   141 type-inference over imports and text; see also HOL/ex/Locales.thy for
   142 some examples;
   143 
   144 * Pure: the following commands have been ``localized'', supporting a
   145 target locale specification "(in name)": 'lemma', 'theorem',
   146 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   147 stored both within the locale and at the theory level (exported and
   148 qualified by the locale name);
   149 
   150 * Pure: theory goals may now be specified in ``long'' form, with
   151 ad-hoc contexts consisting of arbitrary locale elements. for example
   152 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   153 definitions may be given, too); the result is a meta-level rule with
   154 the context elements being discharged in the obvious way;
   155 
   156 * Pure: new proof command 'using' allows to augment currently used
   157 facts after a goal statement ('using' is syntactically analogous to
   158 'apply', but acts on the goal's facts only); this allows chained facts
   159 to be separated into parts given before and after a claim, as in
   160 ``from a and b have C using d and e <proof>'';
   161 
   162 * Pure: renamed "antecedent" case to "rule_context";
   163 
   164 * Pure: new 'judgment' command records explicit information about the
   165 object-logic embedding (used by several tools internally); no longer
   166 use hard-wired "Trueprop";
   167 
   168 * Pure: added 'corollary' command;
   169 
   170 * Pure: fixed 'token_translation' command;
   171 
   172 * Pure: removed obsolete 'exported' attribute;
   173 
   174 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   175 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   176 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   177 
   178 * Pure: method 'atomize' presents local goal premises as object-level
   179 statements (atomic meta-level propositions); setup controlled via
   180 rewrite rules declarations of 'atomize' attribute; example
   181 application: 'induct' method with proper rule statements in improper
   182 proof *scripts*;
   183 
   184 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   185 now consider the syntactic context of assumptions, giving a better
   186 chance to get type-inference of the arguments right (this is
   187 especially important for locales);
   188 
   189 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   190 mode;
   191 
   192 * Pure/obtain: the formal conclusion "thesis", being marked as
   193 ``internal'', may no longer be reference directly in the text;
   194 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   195 situations;
   196 
   197 * Pure: generic 'sym' attribute which declares a rule both as pure
   198 'elim?' and for the 'symmetric' operation;
   199 
   200 * Pure: marginal comments ``--'' may now occur just anywhere in the
   201 text; the fixed correlation with particular command syntax has been
   202 discontinued;
   203 
   204 * Pure: new method 'rules' is particularly well-suited for proof
   205 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   206 but often produces more compact proof terms with less detours;
   207 
   208 * Pure/Provers/classical: simplified integration with pure rule
   209 attributes and methods; the classical "intro?/elim?/dest?"
   210 declarations coincide with the pure ones; the "rule" method no longer
   211 includes classically swapped intros; "intro" and "elim" methods no
   212 longer pick rules from the context; also got rid of ML declarations
   213 AddXIs/AddXEs/AddXDs; all of this has some potential for
   214 INCOMPATIBILITY;
   215 
   216 * Provers/classical: attribute 'swapped' produces classical inversions
   217 of introduction rules;
   218 
   219 * Provers/simplifier: 'simplified' attribute may refer to explicit
   220 rules instead of full simplifier context; 'iff' attribute handles
   221 conditional rules;
   222 
   223 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   224 
   225 * HOL: 'recdef' now fails on unfinished automated proofs, use
   226 "(permissive)" option to recover old behavior;
   227 
   228 * HOL: 'inductive' no longer features separate (collective) attributes
   229 for 'intros' (was found too confusing);
   230 
   231 * HOL: properly declared induction rules less_induct and
   232 wf_induct_rule;
   233 
   234 
   235 *** HOL ***
   236 
   237 * HOL: moved over to sane numeral syntax; the new policy is as
   238 follows:
   239 
   240   - 0 and 1 are polymorphic constants, which are defined on any
   241   numeric type (nat, int, real etc.);
   242 
   243   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   244   binary representation internally;
   245 
   246   - type nat has special constructor Suc, and generally prefers Suc 0
   247   over 1::nat and Suc (Suc 0) over 2::nat;
   248 
   249 This change may cause significant problems of INCOMPATIBILITY; here
   250 are some hints on converting existing sources:
   251 
   252   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   253   entities, so expressions involving "-" (unary or binary minus) need
   254   to be spaced properly;
   255 
   256   - existing occurrences of "1" may need to be constraint "1::nat" or
   257   even replaced by Suc 0; similar for old "2";
   258 
   259   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   260 
   261   - remove all special provisions on numerals in proofs;
   262 
   263 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   264 representation (depends on bin_arith_simps in the default context);
   265 
   266 * HOL: symbolic syntax for x^2 (numeral 2);
   267 
   268 * HOL: the class of all HOL types is now called "type" rather than
   269 "term"; INCOMPATIBILITY, need to adapt references to this type class
   270 in axclass/classes, instance/arities, and (usually rare) occurrences
   271 in typings (of consts etc.); internally the class is called
   272 "HOL.type", ML programs should refer to HOLogic.typeS;
   273 
   274 * HOL/record package improvements:
   275   - new derived operations "fields" to build a partial record section,
   276     "extend" to promote a fixed record to a record scheme, and
   277     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   278     declared as simp by default;
   279   - shared operations ("more", "fields", etc.) now need to be always
   280     qualified) --- potential INCOMPATIBILITY;
   281   - removed "make_scheme" operations (use "make" with "extend") --
   282     INCOMPATIBILITY;
   283   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   284   - provides cases/induct rules for use with corresponding Isar
   285     methods (for concrete records, record schemes, concrete more
   286     parts, and schematic more parts -- in that order);
   287   - internal definitions directly based on a light-weight abstract
   288     theory of product types over typedef rather than datatype;
   289 
   290 * HOL: generic code generator for generating executable ML code from
   291 specifications; specific support for HOL constructs such as inductive
   292 datatypes and sets, as well as recursive functions; can be invoked
   293 via 'generate_code' theory section;
   294 
   295 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   296 
   297 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   298 (beware of argument permutation!);
   299 
   300 * HOL: linorder_less_split superseded by linorder_cases;
   301 
   302 * HOL/List: "nodups" renamed to "distinct";
   303 
   304 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   305 to peripheral theory "Hilbert_Choice";
   306 
   307 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   308 in this (rare) case use:
   309 
   310   delSWrapper "split_all_tac"
   311   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   312 
   313 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   314 MAY FAIL;
   315 
   316 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   317 Isabelle's type classes, ^ on functions and relations has too general
   318 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   319 necessary to attach explicit type constraints;
   320 
   321 * HOL/Relation: the prefix name of the infix "O" has been changed from
   322 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   323 renamed accordingly (eg "compI" -> "rel_compI").
   324 
   325 * HOL: syntax translations now work properly with numerals and records
   326 expressions;
   327 
   328 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   329 of "lam" -- INCOMPATIBILITY;
   330 
   331 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   332 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   333 renamed "Product_Type.unit";
   334 
   335 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   336 
   337 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   338 the "cases" method);
   339 
   340 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   341 Florian Kammüller);
   342 
   343 * HOL/IMP: updated and converted to new-style theory format; several
   344 parts turned into readable document, with proper Isar proof texts and
   345 some explanations (by Gerwin Klein);
   346 
   347 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   348 
   349 * HOL-Hyperreal is now a logic image;
   350 
   351 
   352 *** HOLCF ***
   353 
   354 * Isar: consts/constdefs supports mixfix syntax for continuous
   355 operations;
   356 
   357 * Isar: domain package adapted to new-style theory format, e.g. see
   358 HOLCF/ex/Dnat.thy;
   359 
   360 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   361 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   362 lift.induct_tac, always use UU instead of Undef;
   363 
   364 * HOLCF/IMP: updated and converted to new-style theory;
   365 
   366 
   367 *** ZF ***
   368 
   369 * Isar: proper integration of logic-specific tools and packages,
   370 including theory commands '(co)inductive', '(co)datatype',
   371 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   372 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   373 
   374 * theory Main no longer includes AC; for the Axiom of Choice, base
   375 your theory on Main_ZFC;
   376 
   377 * the integer library now covers quotients and remainders, with many
   378 laws relating division to addition, multiplication, etc.;
   379 
   380 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   381 typeless version of the formalism;
   382 
   383 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   384 format;
   385 
   386 * ZF/Induct: new directory for examples of inductive definitions,
   387 including theory Multiset for multiset orderings; converted to
   388 new-style theory format;
   389 
   390 * ZF: many new theorems about lists, ordinals, etc.;
   391 
   392 
   393 *** General ***
   394 
   395 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   396 variable proof controls level of detail: 0 = no proofs (only oracle
   397 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   398 also ref manual for further ML interfaces;
   399 
   400 * Pure/axclass: removed obsolete ML interface
   401 goal_subclass/goal_arity;
   402 
   403 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   404 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   405 separate tokens, so expressions involving minus need to be spaced
   406 properly;
   407 
   408 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   409 rather than "infixl" or "infixr";
   410 
   411 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   412 sort constraint specifications in type inference; e.g. "x::_::foo"
   413 ensures that the type of "x" is of sort "foo" (but not necessarily a
   414 type variable);
   415 
   416 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   417 control output of nested => (types); the default behavior is
   418 "type_brackets";
   419 
   420 * Pure/syntax: builtin parse translation for "_constify" turns valued
   421 tokens into AST constants;
   422 
   423 * Pure/syntax: prefer later declarations of translations and print
   424 translation functions; potential INCOMPATIBILITY: need to reverse
   425 multiple declarations for same syntax element constant;
   426 
   427 * Pure/show_hyps reset by default (in accordance to existing Isar
   428 practice);
   429 
   430 * Provers/classical: renamed addaltern to addafter, addSaltern to
   431 addSafter;
   432 
   433 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   434 as well;
   435 
   436 * system: tested support for MacOS X; should be able to get Isabelle +
   437 Proof General to work in a plain Terminal after installing Poly/ML
   438 (e.g. from the Isabelle distribution area) and GNU bash alone
   439 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   440 support requires further installations, e.g. from
   441 http://fink.sourceforge.net/);
   442 
   443 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   444 
   445 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   446 of 40 MB), cf. ML_OPTIONS;
   447 
   448 * system: Proof General keywords specification is now part of the
   449 Isabelle distribution (see etc/isar-keywords.el);
   450 
   451 * system: support for persistent Proof General sessions (refrain from
   452 outdating all loaded theories on startup); user may create writable
   453 logic images like this: ``isabelle -q HOL Test'';
   454 
   455 * system: smart selection of Isabelle process versus Isabelle
   456 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   457 run both "isabelle" and "Isabelle" even if file names are badly
   458 damaged (executable inspects the case of the first letter of its own
   459 name); added separate "isabelle-process" and "isabelle-interface";
   460 
   461 * system: refrain from any attempt at filtering input streams; no
   462 longer support ``8bit'' encoding of old isabelle font, instead proper
   463 iso-latin characters may now be used; the related isatools
   464 "symbolinput" and "nonascii" have disappeared as well;
   465 
   466 * system: removed old "xterm" interface (the print modes "xterm" and
   467 "xterm_color" are still available for direct use in a suitable
   468 terminal);
   469 
   470 
   471 
   472 New in Isabelle99-2 (February 2001)
   473 -----------------------------------
   474 
   475 *** Overview of INCOMPATIBILITIES ***
   476 
   477 * HOL: please note that theories in the Library and elsewhere often use the
   478 new-style (Isar) format; to refer to their theorems in an ML script you must
   479 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   480 
   481 * HOL: inductive package no longer splits induction rule aggressively,
   482 but only as far as specified by the introductions given; the old
   483 format may be recovered via ML function complete_split_rule or attribute
   484 'split_rule (complete)';
   485 
   486 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   487 gfp_Tarski to gfp_unfold;
   488 
   489 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   490 
   491 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   492 relation); infix "^^" has been renamed "``"; infix "``" has been
   493 renamed "`"; "univalent" has been renamed "single_valued";
   494 
   495 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   496 operation;
   497 
   498 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   499 
   500 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   501 
   502 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   503 consequence, it is no longer monotonic wrt. the local goal context
   504 (which is now passed through the inductive cases);
   505 
   506 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   507 \<gg> to \<ggreater>;
   508 
   509 
   510 *** Document preparation ***
   511 
   512 * \isabellestyle{NAME} selects version of Isabelle output (currently
   513 available: are "it" for near math-mode best-style output, "sl" for
   514 slanted text style, and "tt" for plain type-writer; if no
   515 \isabellestyle command is given, output is according to slanted
   516 type-writer);
   517 
   518 * support sub/super scripts (for single symbols only), input syntax is
   519 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   520 
   521 * some more standard symbols; see Appendix A of the system manual for
   522 the complete list of symbols defined in isabellesym.sty;
   523 
   524 * improved isabelle style files; more abstract symbol implementation
   525 (should now use \isamath{...} and \isatext{...} in custom symbol
   526 definitions);
   527 
   528 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   529 state; Note that presentation of goal states does not conform to
   530 actual human-readable proof documents.  Please do not include goal
   531 states into document output unless you really know what you are doing!
   532 
   533 * proper indentation of antiquoted output with proportional LaTeX
   534 fonts;
   535 
   536 * no_document ML operator temporarily disables LaTeX document
   537 generation;
   538 
   539 * isatool unsymbolize tunes sources for plain ASCII communication;
   540 
   541 
   542 *** Isar ***
   543 
   544 * Pure: Isar now suffers initial goal statements to contain unbound
   545 schematic variables (this does not conform to actual readable proof
   546 documents, due to unpredictable outcome and non-compositional proof
   547 checking); users who know what they are doing may use schematic goals
   548 for Prolog-style synthesis of proven results;
   549 
   550 * Pure: assumption method (an implicit finishing) now handles actual
   551 rules as well;
   552 
   553 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   554 initial goal, declare "that" only as Pure intro (only for single
   555 steps); the "that" rule assumption may now be involved in implicit
   556 finishing, thus ".." becomes a feasible for trivial obtains;
   557 
   558 * Pure: default proof step now includes 'intro_classes'; thus trivial
   559 instance proofs may be performed by "..";
   560 
   561 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   562 statements as well;
   563 
   564 * Pure: more robust selection of calculational rules;
   565 
   566 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   567 rule (as well as the assumption rule);
   568 
   569 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   570 lemmas, using the graph browser tool;
   571 
   572 * Pure: predict failure of "show" in interactive mode;
   573 
   574 * Pure: 'thms_containing' now takes actual terms as arguments;
   575 
   576 * HOL: improved method 'induct' --- now handles non-atomic goals
   577 (potential INCOMPATIBILITY); tuned error handling;
   578 
   579 * HOL: cases and induct rules now provide explicit hints about the
   580 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   581 any remaining facts are inserted into the goal verbatim;
   582 
   583 * HOL: local contexts (aka cases) may now contain term bindings as
   584 well; the 'cases' and 'induct' methods new provide a ?case binding for
   585 the result to be shown in each case;
   586 
   587 * HOL: added 'recdef_tc' command;
   588 
   589 * isatool convert assists in eliminating legacy ML scripts;
   590 
   591 
   592 *** HOL ***
   593 
   594 * HOL/Library: a collection of generic theories to be used together
   595 with main HOL; the theory loader path already includes this directory
   596 by default; the following existing theories have been moved here:
   597 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   598 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   599 
   600 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   601 modelling and verification task performed in Isabelle/HOL +
   602 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   603 
   604 * HOL/Algebra: special summation operator SUM no longer exists, it has
   605 been replaced by setsum; infix 'assoc' now has priority 50 (like
   606 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   607 'domain', this makes the theory consistent with mathematical
   608 literature;
   609 
   610 * HOL basics: added overloaded operations "inverse" and "divide"
   611 (infix "/"), syntax for generic "abs" operation, generic summation
   612 operator \<Sum>;
   613 
   614 * HOL/typedef: simplified package, provide more useful rules (see also
   615 HOL/subset.thy);
   616 
   617 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   618 now expressed as a proper nested rule (old-style tactic scripts may
   619 require atomize_strip_tac to cope with non-atomic premises);
   620 
   621 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   622 to "split_conv" (old name still available for compatibility);
   623 
   624 * HOL: improved concrete syntax for strings (e.g. allows translation
   625 rules with string literals);
   626 
   627 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   628  and Fleuriot's mechanization of analysis, including the transcendental
   629  functions for the reals;
   630 
   631 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   632 
   633 
   634 *** CTT ***
   635 
   636 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   637 "lam" is displayed as TWO lambda-symbols
   638 
   639 * CTT: theory Main now available, containing everything (that is, Bool
   640 and Arith);
   641 
   642 
   643 *** General ***
   644 
   645 * Pure: the Simplifier has been implemented properly as a derived rule
   646 outside of the actual kernel (at last!); the overall performance
   647 penalty in practical applications is about 50%, while reliability of
   648 the Isabelle inference kernel has been greatly improved;
   649 
   650 * print modes "brackets" and "no_brackets" control output of nested =>
   651 (types) and ==> (props); the default behaviour is "brackets";
   652 
   653 * Provers: fast_tac (and friends) now handle actual object-logic rules
   654 as assumptions as well;
   655 
   656 * system: support Poly/ML 4.0;
   657 
   658 * system: isatool install handles KDE version 1 or 2;
   659 
   660 
   661 
   662 New in Isabelle99-1 (October 2000)
   663 ----------------------------------
   664 
   665 *** Overview of INCOMPATIBILITIES ***
   666 
   667 * HOL: simplification of natural numbers is much changed; to partly
   668 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   669 issue the following ML commands:
   670 
   671   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   672   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   673 
   674 * HOL: simplification no longer dives into case-expressions; this is
   675 controlled by "t.weak_case_cong" for each datatype t;
   676 
   677 * HOL: nat_less_induct renamed to less_induct;
   678 
   679 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   680 fixsome to patch .thy and .ML sources automatically;
   681 
   682   select_equality  -> some_equality
   683   select_eq_Ex     -> some_eq_ex
   684   selectI2EX       -> someI2_ex
   685   selectI2         -> someI2
   686   selectI          -> someI
   687   select1_equality -> some1_equality
   688   Eps_sym_eq       -> some_sym_eq_trivial
   689   Eps_eq           -> some_eq_trivial
   690 
   691 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   692 
   693 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   694 instead);
   695 
   696 * HOL: the recursion equations generated by 'recdef' are now called
   697 f.simps instead of f.rules;
   698 
   699 * HOL: qed_spec_mp now also handles bounded ALL as well;
   700 
   701 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   702 sometimes be needed;
   703 
   704 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   705 
   706 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   707 
   708 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   709 product is now "<*>" instead of "Times"; the lexicographic product is
   710 now "<*lex*>" instead of "**";
   711 
   712 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   713 of main HOL, but was unused); better use HOL's datatype package;
   714 
   715 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   716 the old syntax may be recovered as follows:
   717 
   718   syntax (symbols)
   719     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   720       (infixl "\\<oplus>" 100)
   721 
   722 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   723 
   724 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   725 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   726 internally;
   727 
   728 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   729 changed from A/r to A//r;
   730 
   731 * ZF: new treatment of arithmetic (nat & int) may break some old
   732 proofs;
   733 
   734 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   735 rulify -> rule_format, elimify -> elim_format, ...);
   736 
   737 * Isar/Provers: intro/elim/dest attributes changed; renamed
   738 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   739 should have to change intro!! to intro? only); replaced "delrule" by
   740 "rule del";
   741 
   742 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   743 
   744 * Provers: strengthened force_tac by using new first_best_tac;
   745 
   746 * LaTeX document preparation: several changes of isabelle.sty (see
   747 lib/texinputs);
   748 
   749 
   750 *** Document preparation ***
   751 
   752 * formal comments (text blocks etc.) in new-style theories may now
   753 contain antiquotations of thm/prop/term/typ/text to be presented
   754 according to latex print mode; concrete syntax is like this:
   755 @{term[show_types] "f(x) = a + x"};
   756 
   757 * isatool mkdir provides easy setup of Isabelle session directories,
   758 including proper document sources;
   759 
   760 * generated LaTeX sources are now deleted after successful run
   761 (isatool document -c); may retain a copy somewhere else via -D option
   762 of isatool usedir;
   763 
   764 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   765 style files, achieving self-contained LaTeX sources and simplifying
   766 LaTeX debugging;
   767 
   768 * old-style theories now produce (crude) LaTeX output as well;
   769 
   770 * browser info session directories are now self-contained (may be put
   771 on WWW server seperately); improved graphs of nested sessions; removed
   772 graph for 'all sessions';
   773 
   774 * several improvements in isabelle style files; \isabellestyle{it}
   775 produces fake math mode output; \isamarkupheader is now \section by
   776 default; see lib/texinputs/isabelle.sty etc.;
   777 
   778 
   779 *** Isar ***
   780 
   781 * Isar/Pure: local results and corresponding term bindings are now
   782 subject to Hindley-Milner polymorphism (similar to ML); this
   783 accommodates incremental type-inference very nicely;
   784 
   785 * Isar/Pure: new derived language element 'obtain' supports
   786 generalized existence reasoning;
   787 
   788 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   789 support accumulation of results, without applying any rules yet;
   790 useful to collect intermediate results without explicit name
   791 references, and for use with transitivity rules with more than 2
   792 premises;
   793 
   794 * Isar/Pure: scalable support for case-analysis type proofs: new
   795 'case' language element refers to local contexts symbolically, as
   796 produced by certain proof methods; internally, case names are attached
   797 to theorems as "tags";
   798 
   799 * Isar/Pure: theory command 'hide' removes declarations from
   800 class/type/const name spaces;
   801 
   802 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   803 indicate potential overloading;
   804 
   805 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   806 
   807 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   808 "{a,b,c}" instead of {a,b,c};
   809 
   810 * Isar/Pure now provides its own version of intro/elim/dest
   811 attributes; useful for building new logics, but beware of confusion
   812 with the version in Provers/classical;
   813 
   814 * Isar/Pure: the local context of (non-atomic) goals is provided via
   815 case name 'antecedent';
   816 
   817 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   818 to the current context is now done automatically);
   819 
   820 * Isar/Pure: theory command 'method_setup' provides a simple interface
   821 for definining proof methods in ML;
   822 
   823 * Isar/Provers: intro/elim/dest attributes changed; renamed
   824 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   825 most cases, one should have to change intro!! to intro? only);
   826 replaced "delrule" by "rule del";
   827 
   828 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   829 'symmetric' attribute (the latter supercedes [RS sym]);
   830 
   831 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   832 method modifier); 'simp' method: 'only:' modifier removes loopers as
   833 well (including splits);
   834 
   835 * Isar/Provers: Simplifier and Classical methods now support all kind
   836 of modifiers used in the past, including 'cong', 'iff', etc.
   837 
   838 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   839 of Simplifier and Classical reasoner);
   840 
   841 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   842 now support named cases; major packages (inductive, datatype, primrec,
   843 recdef) support case names and properly name parameters;
   844 
   845 * Isar/HOL: new transitivity rules for substitution in inequalities --
   846 monotonicity conditions are extracted to be proven at end of
   847 calculations;
   848 
   849 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   850 method anyway;
   851 
   852 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   853 split_if split_if_asm; datatype package provides theorems foo.splits =
   854 foo.split foo.split_asm for each datatype;
   855 
   856 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   857 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   858 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   859 use "(cases (simplified))" method in proper proof texts);
   860 
   861 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   862 
   863 * Isar: names of theorems etc. may be natural numbers as well;
   864 
   865 * Isar: 'pr' command: optional arguments for goals_limit and
   866 ProofContext.prems_limit; no longer prints theory contexts, but only
   867 proof states;
   868 
   869 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   870 additional print modes to be specified; e.g. "pr(latex)" will print
   871 proof state according to the Isabelle LaTeX style;
   872 
   873 * Isar: improved support for emulating tactic scripts, including proof
   874 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   875 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   876 (for HOL datatypes);
   877 
   878 * Isar: simplified (more robust) goal selection of proof methods: 1st
   879 goal, all goals, or explicit goal specifier (tactic emulation); thus
   880 'proof method scripts' have to be in depth-first order;
   881 
   882 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   883 
   884 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   885 should instead use individual commands for printing items
   886 (print_commands, print_methods etc.);
   887 
   888 * Isar: added 'nothing' --- the empty list of theorems;
   889 
   890 
   891 *** HOL ***
   892 
   893 * HOL/MicroJava: formalization of a fragment of Java, together with a
   894 corresponding virtual machine and a specification of its bytecode
   895 verifier and a lightweight bytecode verifier, including proofs of
   896 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   897 Cornelia Pusch (see also the homepage of project Bali at
   898 http://isabelle.in.tum.de/Bali/);
   899 
   900 * HOL/Algebra: new theory of rings and univariate polynomials, by
   901 Clemens Ballarin;
   902 
   903 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   904 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   905 Rasmussen;
   906 
   907 * HOL/Lattice: fundamental concepts of lattice theory and order
   908 structures, including duals, properties of bounds versus algebraic
   909 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   910 Theorem for complete lattices etc.; may also serve as a demonstration
   911 for abstract algebraic reasoning using axiomatic type classes, and
   912 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   913 
   914 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   915 von Oheimb;
   916 
   917 * HOL/IMPP: extension of IMP with local variables and mutually
   918 recursive procedures, by David von Oheimb;
   919 
   920 * HOL/Lambda: converted into new-style theory and document;
   921 
   922 * HOL/ex/Multiquote: example of multiple nested quotations and
   923 anti-quotations -- basically a generalized version of de-Bruijn
   924 representation; very useful in avoiding lifting of operations;
   925 
   926 * HOL/record: added general record equality rule to simpset; fixed
   927 select-update simplification procedure to handle extended records as
   928 well; admit "r" as field name;
   929 
   930 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   931 other numeric types and also as the identity of groups, rings, etc.;
   932 
   933 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   934 Types nat and int belong to this axclass;
   935 
   936 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   937    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   938    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   939   two terms #m*u and #n*u are replaced by #(m+n)*u
   940     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   941   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   942     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   943 
   944 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   945 powerful prover for predicate logic but knows nothing of clasets; see
   946 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   947 
   948 * HOL: new version of "case_tac" subsumes both boolean case split and
   949 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   950 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   951 
   952 * HOL: simplification no longer dives into case-expressions: only the
   953 selector expression is simplified, but not the remaining arms; to
   954 enable full simplification of case-expressions for datatype t, you may
   955 remove t.weak_case_cong from the simpset, either globally (Delcongs
   956 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   957 
   958 * HOL/recdef: the recursion equations generated by 'recdef' for
   959 function 'f' are now called f.simps instead of f.rules; if all
   960 termination conditions are proved automatically, these simplification
   961 rules are added to the simpset, as in primrec; rules may be named
   962 individually as well, resulting in a separate list of theorems for
   963 each equation;
   964 
   965 * HOL/While is a new theory that provides a while-combinator. It
   966 permits the definition of tail-recursive functions without the
   967 provision of a termination measure. The latter is necessary once the
   968 invariant proof rule for while is applied.
   969 
   970 * HOL: new (overloaded) notation for the set of elements below/above
   971 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   972 
   973 * HOL: theorems impI, allI, ballI bound as "strip";
   974 
   975 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   976 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   977 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   978 
   979 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   980 
   981 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   982 main HOL, but was unused);
   983 
   984 * HOL: fewer consts declared as global (e.g. have to refer to
   985 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   986 
   987 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   988 in case of overlap with user translations (e.g. judgements over
   989 tuples); (note that the underlying logical represenation is still
   990 bogus);
   991 
   992 
   993 *** ZF ***
   994 
   995 * ZF: simplification automatically cancels common terms in arithmetic
   996 expressions over nat and int;
   997 
   998 * ZF: new treatment of nat to minimize type-checking: all operators
   999 coerce their operands to a natural number using the function natify,
  1000 making the algebraic laws unconditional;
  1001 
  1002 * ZF: as above, for int: operators coerce their operands to an integer
  1003 using the function intify;
  1004 
  1005 * ZF: the integer library now contains many of the usual laws for the
  1006 orderings, including $<=, and monotonicity laws for $+ and $*;
  1007 
  1008 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1009 simplification;
  1010 
  1011 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1012 to the simplifier and classical reasoner simultaneously;
  1013 
  1014 
  1015 *** General ***
  1016 
  1017 * Provers: blast_tac now handles actual object-logic rules as
  1018 assumptions; note that auto_tac uses blast_tac internally as well;
  1019 
  1020 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1021 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1022 
  1023 * Provers: delrules now handles destruct rules as well (no longer need
  1024 explicit make_elim);
  1025 
  1026 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1027   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1028 use instead the strong form,
  1029   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1030 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1031 from destruct-rules;
  1032 
  1033 * Provers: Simplifier.easy_setup provides a fast path to basic
  1034 Simplifier setup for new object-logics;
  1035 
  1036 * Pure: AST translation rules no longer require constant head on LHS;
  1037 
  1038 * Pure: improved name spaces: ambiguous output is qualified; support
  1039 for hiding of names;
  1040 
  1041 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1042 XSYMBOL_HOME; no longer need to do manual configuration in most
  1043 situations;
  1044 
  1045 * system: compression of ML heaps images may now be controlled via -c
  1046 option of isabelle and isatool usedir (currently only observed by
  1047 Poly/ML);
  1048 
  1049 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1050 useful for remote X11);
  1051 
  1052 * system: provide TAGS file for Isabelle sources;
  1053 
  1054 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1055 order;
  1056 
  1057 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1058 timing flag supersedes proof_timing and Toplevel.trace;
  1059 
  1060 * ML: new combinators |>> and |>>> for incremental transformations
  1061 with secondary results (e.g. certain theory extensions):
  1062 
  1063 * ML: PureThy.add_defs gets additional argument to indicate potential
  1064 overloading (usually false);
  1065 
  1066 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1067 results;
  1068 
  1069 
  1070 
  1071 New in Isabelle99 (October 1999)
  1072 --------------------------------
  1073 
  1074 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1075 
  1076 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1077 are no longer simplified.  (This allows the simplifier to unfold recursive
  1078 functional programs.)  To restore the old behaviour, declare
  1079 
  1080     Delcongs [if_weak_cong];
  1081 
  1082 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1083 complement;
  1084 
  1085 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1086 
  1087 * HOL/datatype: mutual_induct_tac no longer exists --
  1088   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1089 
  1090 * HOL/typedef: fixed type inference for representing set; type
  1091 arguments now have to occur explicitly on the rhs as type constraints;
  1092 
  1093 * ZF: The con_defs part of an inductive definition may no longer refer
  1094 to constants declared in the same theory;
  1095 
  1096 * HOL, ZF: the function mk_cases, generated by the inductive
  1097 definition package, has lost an argument.  To simplify its result, it
  1098 uses the default simpset instead of a supplied list of theorems.
  1099 
  1100 * HOL/List: the constructors of type list are now Nil and Cons;
  1101 
  1102 * Simplifier: the type of the infix ML functions
  1103         setSSolver addSSolver setSolver addSolver
  1104 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1105 for packaging solvers. A solver is created via
  1106         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1107 where the string argument is only a comment.
  1108 
  1109 
  1110 *** Proof tools ***
  1111 
  1112 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1113 decision procedure for linear arithmetic. Currently it is used for
  1114 types `nat', `int', and `real' in HOL (see below); it can, should and
  1115 will be instantiated for other types and logics as well.
  1116 
  1117 * The simplifier now accepts rewrite rules with flexible heads, eg
  1118      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1119   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1120   matching.
  1121 
  1122 
  1123 *** General ***
  1124 
  1125 * New Isabelle/Isar subsystem provides an alternative to traditional
  1126 tactical theorem proving; together with the ProofGeneral/isar user
  1127 interface it offers an interactive environment for developing human
  1128 readable proof documents (Isar == Intelligible semi-automated
  1129 reasoning); for further information see isatool doc isar-ref,
  1130 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1131 
  1132 * improved and simplified presentation of theories: better HTML markup
  1133 (including colors), graph views in several sizes; isatool usedir now
  1134 provides a proper interface for user theories (via -P option); actual
  1135 document preparation based on (PDF)LaTeX is available as well (for
  1136 new-style theories only); see isatool doc system for more information;
  1137 
  1138 * native support for Proof General, both for classic Isabelle and
  1139 Isabelle/Isar;
  1140 
  1141 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1142 using the graph browser tool;
  1143 
  1144 * Isabelle manuals now also available as PDF;
  1145 
  1146 * theory loader rewritten from scratch (may not be fully
  1147 bug-compatible); old loadpath variable has been replaced by show_path,
  1148 add_path, del_path, reset_path functions; new operations such as
  1149 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1150 isatool doc ref);
  1151 
  1152 * improved isatool install: option -k creates KDE application icon,
  1153 option -p DIR installs standalone binaries;
  1154 
  1155 * added ML_PLATFORM setting (useful for cross-platform installations);
  1156 more robust handling of platform specific ML images for SML/NJ;
  1157 
  1158 * the settings environment is now statically scoped, i.e. it is never
  1159 created again in sub-processes invoked from isabelle, isatool, or
  1160 Isabelle;
  1161 
  1162 * path element specification '~~' refers to '$ISABELLE_HOME';
  1163 
  1164 * in locales, the "assumes" and "defines" parts may be omitted if
  1165 empty;
  1166 
  1167 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1168 long arrows);
  1169 
  1170 * new print_mode "HTML";
  1171 
  1172 * new flag show_tags controls display of tags of theorems (which are
  1173 basically just comments that may be attached by some tools);
  1174 
  1175 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1176 mode and goal output format:
  1177 
  1178 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1179 244c244
  1180 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1181 ---
  1182 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1183 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1184 181c181
  1185 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1186 ---
  1187 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1188 
  1189 * function bind_thms stores lists of theorems (cf. bind_thm);
  1190 
  1191 * new shorthand tactics ftac, eatac, datac, fatac;
  1192 
  1193 * qed (and friends) now accept "" as result name; in that case the
  1194 theorem is not stored, but proper checks and presentation of the
  1195 result still apply;
  1196 
  1197 * theorem database now also indexes constants "Trueprop", "all",
  1198 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1199 
  1200 
  1201 *** HOL ***
  1202 
  1203 ** HOL arithmetic **
  1204 
  1205 * There are now decision procedures for linear arithmetic over nat and
  1206 int:
  1207 
  1208 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1209 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1210 are treated as atomic; subformulae not involving type `nat' or `int'
  1211 are ignored; quantified subformulae are ignored unless they are
  1212 positive universal or negative existential. The tactic has to be
  1213 invoked by hand and can be a little bit slow. In particular, the
  1214 running time is exponential in the number of occurrences of `min' and
  1215 `max', and `-' on `nat'.
  1216 
  1217 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1218 (negated) (in)equalities among the premises and the conclusion into
  1219 account (i.e. no compound formulae) and does not know about `min' and
  1220 `max', and `-' on `nat'. It is fast and is used automatically by the
  1221 simplifier.
  1222 
  1223 NB: At the moment, these decision procedures do not cope with mixed
  1224 nat/int formulae where the two parts interact, such as `m < n ==>
  1225 int(m) < int(n)'.
  1226 
  1227 * HOL/Numeral provides a generic theory of numerals (encoded
  1228 efficiently as bit strings); setup for types nat/int/real is in place;
  1229 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1230 int, existing theories and proof scripts may require a few additional
  1231 type constraints;
  1232 
  1233 * integer division and remainder can now be performed on constant
  1234 arguments;
  1235 
  1236 * many properties of integer multiplication, division and remainder
  1237 are now available;
  1238 
  1239 * An interface to the Stanford Validity Checker (SVC) is available through the
  1240 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1241 are proved automatically.  SVC must be installed separately, and its results
  1242 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1243 invocation of the underlying oracle).  For SVC see
  1244   http://verify.stanford.edu/SVC
  1245 
  1246 * IsaMakefile: the HOL-Real target now builds an actual image;
  1247 
  1248 
  1249 ** HOL misc **
  1250 
  1251 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1252 (in Isabelle/Isar) -- by Gertrud Bauer;
  1253 
  1254 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1255 analysis for assembly languages with subtypes;
  1256 
  1257 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1258 -- avoids syntactic ambiguities and treats state, transition, and
  1259 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1260 changed syntax and (many) tactics;
  1261 
  1262 * HOL/inductive: Now also handles more general introduction rules such
  1263   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1264   theorems are now maintained within the theory (maintained via the
  1265   "mono" attribute);
  1266 
  1267 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1268   (using function types) such as
  1269 
  1270   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1271 
  1272 * HOL/record: record_simproc (part of the default simpset) takes care
  1273 of selectors applied to updated records; record_split_tac is no longer
  1274 part of the default claset; update_defs may now be removed from the
  1275 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1276 
  1277   claset_ref () := claset() addSWrapper record_split_wrapper;
  1278   Delsimprocs [record_simproc]
  1279 
  1280 * HOL/typedef: fixed type inference for representing set; type
  1281 arguments now have to occur explicitly on the rhs as type constraints;
  1282 
  1283 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1284 names rather than an ML expression;
  1285 
  1286 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1287 supplied later.  Program schemes can be defined, such as
  1288     "While B C s = (if B s then While B C (C s) else s)"
  1289 where the well-founded relation can be chosen after B and C have been given.
  1290 
  1291 * HOL/List: the constructors of type list are now Nil and Cons;
  1292 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1293 course, ML tools referring to List.list.op # etc. have to be adapted;
  1294 
  1295 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1296 disabled by default; run isabelle with option -m HOL to get back to
  1297 the original Gordon/HOL-style output;
  1298 
  1299 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1300 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1301 
  1302 * HOL basic syntax simplified (more orthogonal): all variants of
  1303 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1304 Eps operator is provided as well: "SOME x. P[x]";
  1305 
  1306 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1307 
  1308 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1309 thus available for user theories;
  1310 
  1311 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1312 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1313 time;
  1314 
  1315 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1316 several times and then mp;
  1317 
  1318 
  1319 *** LK ***
  1320 
  1321 * the notation <<...>> is now available as a notation for sequences of
  1322 formulas;
  1323 
  1324 * the simplifier is now installed
  1325 
  1326 * the axiom system has been generalized (thanks to Soren Heilmann)
  1327 
  1328 * the classical reasoner now has a default rule database
  1329 
  1330 
  1331 *** ZF ***
  1332 
  1333 * new primrec section allows primitive recursive functions to be given
  1334 directly (as in HOL) over datatypes and the natural numbers;
  1335 
  1336 * new tactics induct_tac and exhaust_tac for induction (or case
  1337 analysis) over datatypes and the natural numbers;
  1338 
  1339 * the datatype declaration of type T now defines the recursor T_rec;
  1340 
  1341 * simplification automatically does freeness reasoning for datatype
  1342 constructors;
  1343 
  1344 * automatic type-inference, with AddTCs command to insert new
  1345 type-checking rules;
  1346 
  1347 * datatype introduction rules are now added as Safe Introduction rules
  1348 to the claset;
  1349 
  1350 * the syntax "if P then x else y" is now available in addition to
  1351 if(P,x,y);
  1352 
  1353 
  1354 *** Internal programming interfaces ***
  1355 
  1356 * tuned simplifier trace output; new flag debug_simp;
  1357 
  1358 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1359 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1360 
  1361 * AxClass.axclass_tac lost the theory argument;
  1362 
  1363 * tuned current_goals_markers semantics: begin / end goal avoids
  1364 printing empty lines;
  1365 
  1366 * removed prs and prs_fn hook, which was broken because it did not
  1367 include \n in its semantics, forcing writeln to add one
  1368 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1369 string -> unit if you really want to output text without newline;
  1370 
  1371 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1372 plain output, interface builders may have to enable 'isabelle_font'
  1373 mode to get Isabelle font glyphs as before;
  1374 
  1375 * refined token_translation interface; INCOMPATIBILITY: output length
  1376 now of type real instead of int;
  1377 
  1378 * theory loader actions may be traced via new ThyInfo.add_hook
  1379 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1380 your own database of information attached to *whole* theories -- as
  1381 opposed to intra-theory data slots offered via TheoryDataFun;
  1382 
  1383 * proper handling of dangling sort hypotheses (at last!);
  1384 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1385 extra sort hypotheses that can be witnessed from the type signature;
  1386 the force_strip_shyps flag is gone, any remaining shyps are simply
  1387 left in the theorem (with a warning issued by strip_shyps_warning);
  1388 
  1389 
  1390 
  1391 New in Isabelle98-1 (October 1998)
  1392 ----------------------------------
  1393 
  1394 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1395 
  1396 * several changes of automated proof tools;
  1397 
  1398 * HOL: major changes to the inductive and datatype packages, including
  1399 some minor incompatibilities of theory syntax;
  1400 
  1401 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1402 called `inj_on';
  1403 
  1404 * HOL: removed duplicate thms in Arith:
  1405   less_imp_add_less  should be replaced by  trans_less_add1
  1406   le_imp_add_le      should be replaced by  trans_le_add1
  1407 
  1408 * HOL: unary minus is now overloaded (new type constraints may be
  1409 required);
  1410 
  1411 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1412 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1413 now taken as an integer constant.
  1414 
  1415 * Pure: ML function 'theory_of' renamed to 'theory';
  1416 
  1417 
  1418 *** Proof tools ***
  1419 
  1420 * Simplifier:
  1421   1. Asm_full_simp_tac is now more aggressive.
  1422      1. It will sometimes reorient premises if that increases their power to
  1423         simplify.
  1424      2. It does no longer proceed strictly from left to right but may also
  1425         rotate premises to achieve further simplification.
  1426      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1427      old Asm_full_simp_tac in that it does not rotate premises.
  1428   2. The simplifier now knows a little bit about nat-arithmetic.
  1429 
  1430 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1431 allows for selected deletion of wrappers, by introduction of names for
  1432 wrapper functionals.  This implies that addbefore, addSbefore,
  1433 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1434 and that adding two tactics with the same name overwrites the first
  1435 one (emitting a warning).
  1436   type wrapper = (int -> tactic) -> (int -> tactic)
  1437   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1438   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1439   delWrapper, delSWrapper: claset *  string            -> claset
  1440   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1441 
  1442 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1443 semantics; addbefore now affects only the unsafe part of step_tac
  1444 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1445 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1446 by Force_tac;
  1447 
  1448 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1449 compWrapper; added safe wrapper (and access functions for it);
  1450 
  1451 * HOL/split_all_tac is now much faster and fails if there is nothing
  1452 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1453 and the names of the automatically generated variables have changed.
  1454 split_all_tac has moved within claset() from unsafe wrappers to safe
  1455 wrappers, which means that !!-bound variables are split much more
  1456 aggressively, and safe_tac and clarify_tac now split such variables.
  1457 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1458 Note: the same holds for record_split_tac, which does the job of
  1459 split_all_tac for record fields.
  1460 
  1461 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1462 permanently to the default simpset using Addsplits just like
  1463 Addsimps. They can be removed via Delsplits just like
  1464 Delsimps. Lower-case versions are also available.
  1465 
  1466 * HOL/Simplifier: The rule split_if is now part of the default
  1467 simpset. This means that the simplifier will eliminate all occurrences
  1468 of if-then-else in the conclusion of a goal. To prevent this, you can
  1469 either remove split_if completely from the default simpset by
  1470 `Delsplits [split_if]' or remove it in a specific call of the
  1471 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1472 other case splitting rules to/from the default simpset: every datatype
  1473 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1474 t is the name of the datatype).
  1475 
  1476 * Classical reasoner / Simplifier combination: new force_tac (and
  1477 derivatives Force_tac, force) combines rewriting and classical
  1478 reasoning (and whatever other tools) similarly to auto_tac, but is
  1479 aimed to solve the given subgoal completely.
  1480 
  1481 
  1482 *** General ***
  1483 
  1484 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1485 and `goalw': the theory is no longer needed as an explicit argument -
  1486 the current theory context is used; assumptions are no longer returned
  1487 at the ML-level unless one of them starts with ==> or !!; it is
  1488 recommended to convert to these new commands using isatool fixgoal
  1489 (backup your sources first!);
  1490 
  1491 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1492 the current theory context, and 'theory' to lookup stored theories;
  1493 
  1494 * new theory section 'locale' for declaring constants, assumptions and
  1495 definitions that have local scope;
  1496 
  1497 * new theory section 'nonterminals' for purely syntactic types;
  1498 
  1499 * new theory section 'setup' for generic ML setup functions
  1500 (e.g. package initialization);
  1501 
  1502 * the distribution now includes Isabelle icons: see
  1503 lib/logo/isabelle-{small,tiny}.xpm;
  1504 
  1505 * isatool install - install binaries with absolute references to
  1506 ISABELLE_HOME/bin;
  1507 
  1508 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1509 
  1510 * print mode 'emacs' reserved for Isamode;
  1511 
  1512 * support multiple print (ast) translations per constant name;
  1513 
  1514 * theorems involving oracles are now printed with a suffixed [!];
  1515 
  1516 
  1517 *** HOL ***
  1518 
  1519 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1520 
  1521 * HOL/inductive package reorganized and improved: now supports mutual
  1522 definitions such as
  1523 
  1524   inductive EVEN ODD
  1525     intrs
  1526       null "0 : EVEN"
  1527       oddI "n : EVEN ==> Suc n : ODD"
  1528       evenI "n : ODD ==> Suc n : EVEN"
  1529 
  1530 new theorem list "elims" contains an elimination rule for each of the
  1531 recursive sets; inductive definitions now handle disjunctive premises
  1532 correctly (also ZF);
  1533 
  1534 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1535 "mutual_induct" no longer exists - the induction rule is always
  1536 contained in "induct";
  1537 
  1538 
  1539 * HOL/datatype package re-implemented and greatly improved: now
  1540 supports mutually recursive datatypes such as
  1541 
  1542   datatype
  1543     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1544             | SUM ('a aexp) ('a aexp)
  1545             | DIFF ('a aexp) ('a aexp)
  1546             | NUM 'a
  1547   and
  1548     'a bexp = LESS ('a aexp) ('a aexp)
  1549             | AND ('a bexp) ('a bexp)
  1550             | OR ('a bexp) ('a bexp)
  1551 
  1552 as well as indirectly recursive datatypes such as
  1553 
  1554   datatype
  1555     ('a, 'b) term = Var 'a
  1556                   | App 'b ((('a, 'b) term) list)
  1557 
  1558 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1559 induction on mutually / indirectly recursive datatypes.
  1560 
  1561 Primrec equations are now stored in theory and can be accessed via
  1562 <function_name>.simps.
  1563 
  1564 INCOMPATIBILITIES:
  1565 
  1566   - Theories using datatypes must now have theory Datatype as an
  1567     ancestor.
  1568   - The specific <typename>.induct_tac no longer exists - use the
  1569     generic induct_tac instead.
  1570   - natE has been renamed to nat.exhaust - use exhaust_tac
  1571     instead of res_inst_tac ... natE. Note that the variable
  1572     names in nat.exhaust differ from the names in natE, this
  1573     may cause some "fragile" proofs to fail.
  1574   - The theorems split_<typename>_case and split_<typename>_case_asm
  1575     have been renamed to <typename>.split and <typename>.split_asm.
  1576   - Since default sorts of type variables are now handled correctly,
  1577     some datatype definitions may have to be annotated with explicit
  1578     sort constraints.
  1579   - Primrec definitions no longer require function name and type
  1580     of recursive argument.
  1581 
  1582 Consider using isatool fixdatatype to adapt your theories and proof
  1583 scripts to the new package (backup your sources first!).
  1584 
  1585 
  1586 * HOL/record package: considerably improved implementation; now
  1587 includes concrete syntax for record types, terms, updates; theorems
  1588 for surjective pairing and splitting !!-bound record variables; proof
  1589 support is as follows:
  1590 
  1591   1) standard conversions (selectors or updates applied to record
  1592 constructor terms) are part of the standard simpset;
  1593 
  1594   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1595 made part of standard simpset and claset via addIffs;
  1596 
  1597   3) a tactic for record field splitting (record_split_tac) is part of
  1598 the standard claset (addSWrapper);
  1599 
  1600 To get a better idea about these rules you may retrieve them via
  1601 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1602 the name of your record type.
  1603 
  1604 The split tactic 3) conceptually simplifies by the following rule:
  1605 
  1606   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1607 
  1608 Thus any record variable that is bound by meta-all will automatically
  1609 blow up into some record constructor term, consequently the
  1610 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1611 solve record problems automatically.
  1612 
  1613 
  1614 * reorganized the main HOL image: HOL/Integ and String loaded by
  1615 default; theory Main includes everything;
  1616 
  1617 * automatic simplification of integer sums and comparisons, using cancellation;
  1618 
  1619 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1620 
  1621 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1622 
  1623 * many new identities for unions, intersections, set difference, etc.;
  1624 
  1625 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1626 called split_if, split_split, split_sum_case and split_nat_case (to go
  1627 with add/delsplits);
  1628 
  1629 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1630 (?x::unit) = (); this is made part of the default simpset, which COULD
  1631 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1632 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1633 unit_abs_eta_conv is added in order to counter the effect of
  1634 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1635 %u.f();
  1636 
  1637 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1638 makes more sense);
  1639 
  1640 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1641   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1642   disjointness reasoning but breaking a few old proofs.
  1643 
  1644 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1645 to 'converse' from 'inverse' (for compatibility with ZF and some
  1646 literature);
  1647 
  1648 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1649 the well-founded relation;
  1650 
  1651 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1652     Compl A.  The "Compl" syntax remains available as input syntax for this
  1653     release ONLY.
  1654 
  1655 * HOL/Update: new theory of function updates:
  1656     f(a:=b) == %x. if x=a then b else f x
  1657 may also be iterated as in f(a:=b,c:=d,...);
  1658 
  1659 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1660 
  1661 * HOL/List:
  1662   - new function list_update written xs[i:=v] that updates the i-th
  1663     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1664   - new function `upt' written [i..j(] which generates the list
  1665     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1666     bound write [i..j], which is a shorthand for [i..j+1(].
  1667   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1668 
  1669 * HOL/Arith:
  1670   - removed 'pred' (predecessor) function;
  1671   - generalized some theorems about n-1;
  1672   - many new laws about "div" and "mod";
  1673   - new laws about greatest common divisors (see theory ex/Primes);
  1674 
  1675 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1676 instead of "inverse";
  1677 
  1678 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1679   of the multiset ordering;
  1680 
  1681 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1682   (not included by default);
  1683 
  1684 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1685 
  1686 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1687   programs, i.e. different program variables may have different types.
  1688 
  1689 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1690   [previously, this check worked only if the rewrite rule was unconditional]
  1691   Now rew can involve either definitions or equalities (either == or =).
  1692 
  1693 
  1694 *** ZF ***
  1695 
  1696 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1697   only the theorems proved on ZF.ML;
  1698 
  1699 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1700   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1701   disjointness reasoning but breaking a few old proofs.
  1702 
  1703 * ZF/Update: new theory of function updates
  1704     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1705   may also be iterated as in f(a:=b,c:=d,...);
  1706 
  1707 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1708 
  1709 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1710   [previously, this check worked only if the rewrite rule was unconditional]
  1711   Now rew can involve either definitions or equalities (either == or =).
  1712 
  1713 * case_tac provided for compatibility with HOL
  1714     (like the old excluded_middle_tac, but with subgoals swapped)
  1715 
  1716 
  1717 *** Internal programming interfaces ***
  1718 
  1719 * Pure: several new basic modules made available for general use, see
  1720 also src/Pure/README;
  1721 
  1722 * improved the theory data mechanism to support encapsulation (data
  1723 kind name replaced by private Object.kind, acting as authorization
  1724 key); new type-safe user interface via functor TheoryDataFun; generic
  1725 print_data function becomes basically useless;
  1726 
  1727 * removed global_names compatibility flag -- all theory declarations
  1728 are qualified by default;
  1729 
  1730 * module Pure/Syntax now offers quote / antiquote translation
  1731 functions (useful for Hoare logic etc. with implicit dependencies);
  1732 see HOL/ex/Antiquote for an example use;
  1733 
  1734 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1735 cterm -> thm;
  1736 
  1737 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1738 subgoal;
  1739 
  1740 * Display.print_goals function moved to Locale.print_goals;
  1741 
  1742 * standard print function for goals supports current_goals_markers
  1743 variable for marking begin of proof, end of proof, start of goal; the
  1744 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1745 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1746 for example;
  1747 
  1748 
  1749 
  1750 New in Isabelle98 (January 1998)
  1751 --------------------------------
  1752 
  1753 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1754 
  1755 * changed lexical syntax of terms / types: dots made part of long
  1756 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1757 
  1758 * simpset (and claset) reference variable replaced by functions
  1759 simpset / simpset_ref;
  1760 
  1761 * no longer supports theory aliases (via merge) and non-trivial
  1762 implicit merge of thms' signatures;
  1763 
  1764 * most internal names of constants changed due to qualified names;
  1765 
  1766 * changed Pure/Sequence interface (see Pure/seq.ML);
  1767 
  1768 
  1769 *** General Changes ***
  1770 
  1771 * hierachically structured name spaces (for consts, types, axms, thms
  1772 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1773 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1774 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1775 long_names for fully qualified output names; NOTE: ML programs
  1776 (special tactics, packages etc.) referring to internal names may have
  1777 to be adapted to cope with fully qualified names; in case of severe
  1778 backward campatibility problems try setting 'global_names' at compile
  1779 time to have enrything declared within a flat name space; one may also
  1780 fine tune name declarations in theories via the 'global' and 'local'
  1781 section;
  1782 
  1783 * reimplemented the implicit simpset and claset using the new anytype
  1784 data filed in signatures; references simpset:simpset ref etc. are
  1785 replaced by functions simpset:unit->simpset and
  1786 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1787 to patch your ML files accordingly;
  1788 
  1789 * HTML output now includes theory graph data for display with Java
  1790 applet or isatool browser; data generated automatically via isatool
  1791 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1792 
  1793 * defs may now be conditional; improved rewrite_goals_tac to handle
  1794 conditional equations;
  1795 
  1796 * defs now admits additional type arguments, using TYPE('a) syntax;
  1797 
  1798 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1799 creates a new theory node; implicit merge of thms' signatures is
  1800 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1801 transfer:theory->thm->thm in (rare) cases;
  1802 
  1803 * improved handling of draft signatures / theories; draft thms (and
  1804 ctyps, cterms) are automatically promoted to real ones;
  1805 
  1806 * slightly changed interfaces for oracles: admit many per theory, named
  1807 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1808 
  1809 * print_goals: optional output of const types (set show_consts and
  1810 show_types);
  1811 
  1812 * improved output of warnings (###) and errors (***);
  1813 
  1814 * subgoal_tac displays a warning if the new subgoal has type variables;
  1815 
  1816 * removed old README and Makefiles;
  1817 
  1818 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1819 
  1820 * removed obsolete init_pps and init_database;
  1821 
  1822 * deleted the obsolete tactical STATE, which was declared by
  1823     fun STATE tacfun st = tacfun st st;
  1824 
  1825 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1826 (which abbreviates $HOME);
  1827 
  1828 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1829 use isatool fixseq to adapt your ML programs (this works for fully
  1830 qualified references to the Sequence structure only!);
  1831 
  1832 * use_thy no longer requires writable current directory; it always
  1833 reloads .ML *and* .thy file, if either one is out of date;
  1834 
  1835 
  1836 *** Classical Reasoner ***
  1837 
  1838 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1839 tactics that use classical reasoning to simplify a subgoal without
  1840 splitting it into several subgoals;
  1841 
  1842 * Safe_tac: like safe_tac but uses the default claset;
  1843 
  1844 
  1845 *** Simplifier ***
  1846 
  1847 * added simplification meta rules:
  1848     (asm_)(full_)simplify: simpset -> thm -> thm;
  1849 
  1850 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1851 logics (again);
  1852 
  1853 * added prems argument to simplification procedures;
  1854 
  1855 * HOL, FOL, ZF: added infix function `addsplits':
  1856   instead of `<simpset> setloop (split_tac <thms>)'
  1857   you can simply write `<simpset> addsplits <thms>'
  1858 
  1859 
  1860 *** Syntax ***
  1861 
  1862 * TYPE('a) syntax for type reflection terms;
  1863 
  1864 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1865 
  1866 * pretty printer: changed order of mixfix annotation preference (again!);
  1867 
  1868 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1869 
  1870 
  1871 *** HOL ***
  1872 
  1873 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1874   with `addloop' of the simplifier to faciliate case splitting in premises.
  1875 
  1876 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1877 
  1878 * HOL/Auth: new protocol proofs including some for the Internet
  1879   protocol TLS;
  1880 
  1881 * HOL/Map: new theory of `maps' a la VDM;
  1882 
  1883 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1884 cancelling out common nat summands from =, <, <= (in)equalities, or
  1885 differences; simplification procedures nat_cancel_factor for
  1886 cancelling common factor from =, <, <= (in)equalities over natural
  1887 sums; nat_cancel contains both kinds of procedures, it is installed by
  1888 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1889 
  1890 * HOL/simplifier: terms of the form
  1891   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1892   are rewritten to
  1893   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1894   and those of the form
  1895   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1896   are rewritten to
  1897   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1898 
  1899 * HOL/datatype
  1900   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1901 
  1902   P(t_case f1 ... fn x) =
  1903      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1904         ...
  1905        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1906      )
  1907 
  1908   and a theorem `split_t_case_asm' of the form
  1909 
  1910   P(t_case f1 ... fn x) =
  1911     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1912         ...
  1913        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1914      )
  1915   which can be added to a simpset via `addsplits'. The existing theorems
  1916   expand_list_case and expand_option_case have been renamed to
  1917   split_list_case and split_option_case.
  1918 
  1919 * HOL/Arithmetic:
  1920   - `pred n' is automatically converted to `n-1'.
  1921     Users are strongly encouraged not to use `pred' any longer,
  1922     because it will disappear altogether at some point.
  1923   - Users are strongly encouraged to write "0 < n" rather than
  1924     "n ~= 0". Theorems and proof tools have been modified towards this
  1925     `standard'.
  1926 
  1927 * HOL/Lists:
  1928   the function "set_of_list" has been renamed "set" (and its theorems too);
  1929   the function "nth" now takes its arguments in the reverse order and
  1930   has acquired the infix notation "!" as in "xs!n".
  1931 
  1932 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1933 
  1934 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1935   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1936 
  1937 * HOL/record: extensible records with schematic structural subtyping
  1938 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1939 still lacks various theorems and concrete record syntax;
  1940 
  1941 
  1942 *** HOLCF ***
  1943 
  1944 * removed "axioms" and "generated by" sections;
  1945 
  1946 * replaced "ops" section by extended "consts" section, which is capable of
  1947   handling the continuous function space "->" directly;
  1948 
  1949 * domain package:
  1950   . proves theorems immediately and stores them in the theory,
  1951   . creates hierachical name space,
  1952   . now uses normal mixfix annotations (instead of cinfix...),
  1953   . minor changes to some names and values (for consistency),
  1954   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1955   . separator between mutual domain defs: changed "," to "and",
  1956   . improved handling of sort constraints;  now they have to
  1957     appear on the left-hand side of the equations only;
  1958 
  1959 * fixed LAM <x,y,zs>.b syntax;
  1960 
  1961 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1962 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1963 
  1964 
  1965 *** FOL and ZF ***
  1966 
  1967 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1968   with `addloop' of the simplifier to faciliate case splitting in premises.
  1969 
  1970 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1971 in HOL, they strip ALL and --> from proved theorems;
  1972 
  1973 
  1974 
  1975 New in Isabelle94-8 (May 1997)
  1976 ------------------------------
  1977 
  1978 *** General Changes ***
  1979 
  1980 * new utilities to build / run / maintain Isabelle etc. (in parts
  1981 still somewhat experimental); old Makefiles etc. still functional;
  1982 
  1983 * new 'Isabelle System Manual';
  1984 
  1985 * INSTALL text, together with ./configure and ./build scripts;
  1986 
  1987 * reimplemented type inference for greater efficiency, better error
  1988 messages and clean internal interface;
  1989 
  1990 * prlim command for dealing with lots of subgoals (an easier way of
  1991 setting goals_limit);
  1992 
  1993 
  1994 *** Syntax ***
  1995 
  1996 * supports alternative (named) syntax tables (parser and pretty
  1997 printer); internal interface is provided by add_modesyntax(_i);
  1998 
  1999 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2000 be used in conjunction with the Isabelle symbol font; uses the
  2001 "symbols" syntax table;
  2002 
  2003 * added token_translation interface (may translate name tokens in
  2004 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2005 the current print_mode); IMPORTANT: user print translation functions
  2006 are responsible for marking newly introduced bounds
  2007 (Syntax.mark_boundT);
  2008 
  2009 * token translations for modes "xterm" and "xterm_color" that display
  2010 names in bold, underline etc. or colors (which requires a color
  2011 version of xterm);
  2012 
  2013 * infixes may now be declared with names independent of their syntax;
  2014 
  2015 * added typed_print_translation (like print_translation, but may
  2016 access type of constant);
  2017 
  2018 
  2019 *** Classical Reasoner ***
  2020 
  2021 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2022 some limitations.  Blast_tac...
  2023   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2024   + ignores elimination rules that don't have the correct format
  2025         (the conclusion MUST be a formula variable)
  2026   + ignores types, which can make HOL proofs fail
  2027   + rules must not require higher-order unification, e.g. apply_type in ZF
  2028     [message "Function Var's argument not a bound variable" relates to this]
  2029   + its proof strategy is more general but can actually be slower
  2030 
  2031 * substitution with equality assumptions no longer permutes other
  2032 assumptions;
  2033 
  2034 * minor changes in semantics of addafter (now called addaltern); renamed
  2035 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2036 (and access functions for it);
  2037 
  2038 * improved combination of classical reasoner and simplifier:
  2039   + functions for handling clasimpsets
  2040   + improvement of addss: now the simplifier is called _after_ the
  2041     safe steps.
  2042   + safe variant of addss called addSss: uses safe simplifications
  2043     _during_ the safe steps. It is more complete as it allows multiple
  2044     instantiations of unknowns (e.g. with slow_tac).
  2045 
  2046 *** Simplifier ***
  2047 
  2048 * added interface for simplification procedures (functions that
  2049 produce *proven* rewrite rules on the fly, depending on current
  2050 redex);
  2051 
  2052 * ordering on terms as parameter (used for ordered rewriting);
  2053 
  2054 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2055 
  2056 * the solver is now split into a safe and an unsafe part.
  2057 This should be invisible for the normal user, except that the
  2058 functions setsolver and addsolver have been renamed to setSolver and
  2059 addSolver; added safe_asm_full_simp_tac;
  2060 
  2061 
  2062 *** HOL ***
  2063 
  2064 * a generic induction tactic `induct_tac' which works for all datatypes and
  2065 also for type `nat';
  2066 
  2067 * a generic case distinction tactic `exhaust_tac' which works for all
  2068 datatypes and also for type `nat';
  2069 
  2070 * each datatype comes with a function `size';
  2071 
  2072 * patterns in case expressions allow tuple patterns as arguments to
  2073 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2074 
  2075 * primrec now also works with type nat;
  2076 
  2077 * recdef: a new declaration form, allows general recursive functions to be
  2078 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2079 
  2080 * the constant for negation has been renamed from "not" to "Not" to
  2081 harmonize with FOL, ZF, LK, etc.;
  2082 
  2083 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2084 infinite lists;
  2085 
  2086 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2087 
  2088 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2089 problems in commutative rings, using axiomatic type classes for + and *;
  2090 
  2091 * more examples in HOL/MiniML and HOL/Auth;
  2092 
  2093 * more default rewrite rules for quantifiers, union/intersection;
  2094 
  2095 * a new constant `arbitrary == @x.False';
  2096 
  2097 * HOLCF/IOA replaces old HOL/IOA;
  2098 
  2099 * HOLCF changes: derived all rules and arities
  2100   + axiomatic type classes instead of classes
  2101   + typedef instead of faking type definitions
  2102   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2103   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2104   + eliminated the types void, one, tr
  2105   + use unit lift and bool lift (with translations) instead of one and tr
  2106   + eliminated blift from Lift3.thy (use Def instead of blift)
  2107   all eliminated rules are derived as theorems --> no visible changes ;
  2108 
  2109 
  2110 *** ZF ***
  2111 
  2112 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2113 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2114 as ZF_cs addSIs [equalityI];
  2115 
  2116 
  2117 
  2118 New in Isabelle94-7 (November 96)
  2119 ---------------------------------
  2120 
  2121 * allowing negative levels (as offsets) in prlev and choplev;
  2122 
  2123 * super-linear speedup for large simplifications;
  2124 
  2125 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2126 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2127 FAIL); can suppress it using the command Delsimps (ex_simps @
  2128 all_simps); De Morgan laws are also now included, by default;
  2129 
  2130 * improved printing of ==>  :  ~:
  2131 
  2132 * new object-logic "Sequents" adds linear logic, while replacing LK
  2133 and Modal (thanks to Sara Kalvala);
  2134 
  2135 * HOL/Auth: correctness proofs for authentication protocols;
  2136 
  2137 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2138 examples on HOL/Auth);
  2139 
  2140 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2141 the rewriter and classical reasoner simultaneously;
  2142 
  2143 * function uresult no longer returns theorems in "standard" format;
  2144 regain previous version by: val uresult = standard o uresult;
  2145 
  2146 
  2147 
  2148 New in Isabelle94-6
  2149 -------------------
  2150 
  2151 * oracles -- these establish an interface between Isabelle and trusted
  2152 external reasoners, which may deliver results as theorems;
  2153 
  2154 * proof objects (in particular record all uses of oracles);
  2155 
  2156 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2157 
  2158 * "constdefs" section in theory files;
  2159 
  2160 * "primrec" section (HOL) no longer requires names;
  2161 
  2162 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2163 
  2164 
  2165 
  2166 New in Isabelle94-5
  2167 -------------------
  2168 
  2169 * reduced space requirements;
  2170 
  2171 * automatic HTML generation from theories;
  2172 
  2173 * theory files no longer require "..." (quotes) around most types;
  2174 
  2175 * new examples, including two proofs of the Church-Rosser theorem;
  2176 
  2177 * non-curried (1994) version of HOL is no longer distributed;
  2178 
  2179 
  2180 
  2181 New in Isabelle94-4
  2182 -------------------
  2183 
  2184 * greatly reduced space requirements;
  2185 
  2186 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2187 
  2188 * searchable theorem database (see the section "Retrieving theorems" on
  2189 page 8 of the Reference Manual);
  2190 
  2191 * new examples, including Grabczewski's monumental case study of the
  2192 Axiom of Choice;
  2193 
  2194 * The previous version of HOL renamed to Old_HOL;
  2195 
  2196 * The new version of HOL (previously called CHOL) uses a curried syntax
  2197 for functions.  Application looks like f a b instead of f(a,b);
  2198 
  2199 * Mutually recursive inductive definitions finally work in HOL;
  2200 
  2201 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2202 translates to the operator "split";
  2203 
  2204 
  2205 
  2206 New in Isabelle94-3
  2207 -------------------
  2208 
  2209 * new infix operator, addss, allowing the classical reasoner to
  2210 perform simplification at each step of its search.  Example:
  2211         fast_tac (cs addss ss)
  2212 
  2213 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2214 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2215 look like (a,b) instead of <a,b>;
  2216 
  2217 * PLEASE NOTE: CHOL will eventually replace HOL!
  2218 
  2219 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2220 It translates to the operator "split".  A new theory of integers is available;
  2221 
  2222 * In ZF, integer numerals now denote two's-complement binary integers.
  2223 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2224 
  2225 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2226 of the Axiom of Choice;
  2227 
  2228 
  2229 
  2230 New in Isabelle94-2
  2231 -------------------
  2232 
  2233 * Significantly faster resolution;
  2234 
  2235 * the different sections in a .thy file can now be mixed and repeated
  2236 freely;
  2237 
  2238 * Database of theorems for FOL, HOL and ZF.  New
  2239 commands including qed, qed_goal and bind_thm store theorems in the database.
  2240 
  2241 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2242 a given theory (thms_of), or find out what theory a theorem was proved in
  2243 (theory_of_thm);
  2244 
  2245 * Bugs fixed in the inductive definition and datatype packages;
  2246 
  2247 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2248 and HOL_dup_cs obsolete;
  2249 
  2250 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2251 have been removed;
  2252 
  2253 * Simpler definition of function space in ZF;
  2254 
  2255 * new results about cardinal and ordinal arithmetic in ZF;
  2256 
  2257 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2258 types;
  2259 
  2260 
  2261 $Id$