NEWS
author wenzelm
Fri Jul 26 21:09:39 2002 +0200 (2002-07-26)
changeset 13425 119ae829ad9b
parent 13410 f2cd09766864
child 13443 1c3327c348b3
permissions -rw-r--r--
support for split assumptions in cases (hyps vs. prems);
     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 * improved induct method: assumptions introduced by case "foo" are
    19 split into "foo.hyps" (from the rule) and "foo.prems" (from the goal
    20 statement); "foo" still refers to all facts collectively;
    21 
    22 * improved thms_containing: proper indexing of facts instead of raw
    23 theorems; check validity of results wrt. current name space; include
    24 local facts of proof configuration (also covers active locales); an
    25 optional limit for the number of printed facts may be given (the
    26 default is 40);
    27 
    28 
    29 *** HOL ***
    30 
    31 * attribute [symmetric] now works for relations as well. It turns
    32   (x,y) : R^-1 into (y,x) : R, and vice versa.
    33 
    34 * arith(_tac) does now know about div k and mod k where k is a numeral of
    35   type nat or int. It can solve simple goals like
    36   "0 < n ==> n div 2 < (n::nat)"
    37   but fails if divisibility plays a role like in
    38   "n div 2 + (n+1) div 2 = (n::nat)".
    39 * simp's arithmetic capabilities have been enhanced a bit:
    40   it now takes ~= in premises into account (by performing a case split).
    41 
    42 
    43 
    44 New in Isabelle2002 (March 2002)
    45 --------------------------------
    46 
    47 *** Document preparation ***
    48 
    49 * greatly simplified document preparation setup, including more
    50 graceful interpretation of isatool usedir -i/-d/-D options, and more
    51 instructive isatool mkdir; users should basically be able to get
    52 started with "isatool mkdir HOL Test && isatool make"; alternatively,
    53 users may run a separate document processing stage manually like this:
    54 "isatool usedir -D output HOL Test && isatool document Test/output";
    55 
    56 * theory dependency graph may now be incorporated into documents;
    57 isatool usedir -g true will produce session_graph.eps/.pdf for use
    58 with \includegraphics of LaTeX;
    59 
    60 * proper spacing of consecutive markup elements, especially text
    61 blocks after section headings;
    62 
    63 * support bold style (for single symbols only), input syntax is like
    64 this: "\<^bold>\<alpha>" or "\<^bold>A";
    65 
    66 * \<bullet> is now output as bold \cdot by default, which looks much
    67 better in printed text;
    68 
    69 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
    70 note that these symbols are currently unavailable in Proof General /
    71 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
    72 
    73 * isatool latex no longer depends on changed TEXINPUTS, instead
    74 isatool document copies the Isabelle style files to the target
    75 location;
    76 
    77 
    78 *** Isar ***
    79 
    80 * Pure/Provers: improved proof by cases and induction;
    81   - 'case' command admits impromptu naming of parameters (such as
    82     "case (Suc n)");
    83   - 'induct' method divinates rule instantiation from the inductive
    84     claim; no longer requires excessive ?P bindings for proper
    85     instantiation of cases;
    86   - 'induct' method properly enumerates all possibilities of set/type
    87     rules; as a consequence facts may be also passed through *type*
    88     rules without further ado;
    89   - 'induct' method now derives symbolic cases from the *rulified*
    90     rule (before it used to rulify cases stemming from the internal
    91     atomized version); this means that the context of a non-atomic
    92     statement becomes is included in the hypothesis, avoiding the
    93     slightly cumbersome show "PROP ?case" form;
    94   - 'induct' may now use elim-style induction rules without chaining
    95     facts, using ``missing'' premises from the goal state; this allows
    96     rules stemming from inductive sets to be applied in unstructured
    97     scripts, while still benefitting from proper handling of non-atomic
    98     statements; NB: major inductive premises need to be put first, all
    99     the rest of the goal is passed through the induction;
   100   - 'induct' proper support for mutual induction involving non-atomic
   101     rule statements (uses the new concept of simultaneous goals, see
   102     below);
   103   - append all possible rule selections, but only use the first
   104     success (no backtracking);
   105   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   106   - undeclared rule case names default to numbers 1, 2, 3, ...;
   107   - added 'print_induct_rules' (covered by help item in recent Proof
   108     General versions);
   109   - moved induct/cases attributes to Pure, methods to Provers;
   110   - generic method setup instantiated for FOL and HOL;
   111 
   112 * Pure: support multiple simultaneous goal statements, for example
   113 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   114 meta-level mechanism, this acts as if several individual goals had
   115 been stated separately; in particular common proof methods need to be
   116 repeated in order to cover all claims; note that a single elimination
   117 step is *not* sufficient to establish the two conjunctions, so this
   118 fails:
   119 
   120   assume "A & B" then have A and B ..   (*".." fails*)
   121 
   122 better use "obtain" in situations as above; alternative refer to
   123 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   124 
   125 * Pure: proper integration with ``locales''; unlike the original
   126 version by Florian Kammüller, Isar locales package high-level proof
   127 contexts rather than raw logical ones (e.g. we admit to include
   128 attributes everywhere); operations on locales include merge and
   129 rename; support for implicit arguments (``structures''); simultaneous
   130 type-inference over imports and text; see also HOL/ex/Locales.thy for
   131 some examples;
   132 
   133 * Pure: the following commands have been ``localized'', supporting a
   134 target locale specification "(in name)": 'lemma', 'theorem',
   135 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   136 stored both within the locale and at the theory level (exported and
   137 qualified by the locale name);
   138 
   139 * Pure: theory goals may now be specified in ``long'' form, with
   140 ad-hoc contexts consisting of arbitrary locale elements. for example
   141 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   142 definitions may be given, too); the result is a meta-level rule with
   143 the context elements being discharged in the obvious way;
   144 
   145 * Pure: new proof command 'using' allows to augment currently used
   146 facts after a goal statement ('using' is syntactically analogous to
   147 'apply', but acts on the goal's facts only); this allows chained facts
   148 to be separated into parts given before and after a claim, as in
   149 ``from a and b have C using d and e <proof>'';
   150 
   151 * Pure: renamed "antecedent" case to "rule_context";
   152 
   153 * Pure: new 'judgment' command records explicit information about the
   154 object-logic embedding (used by several tools internally); no longer
   155 use hard-wired "Trueprop";
   156 
   157 * Pure: added 'corollary' command;
   158 
   159 * Pure: fixed 'token_translation' command;
   160 
   161 * Pure: removed obsolete 'exported' attribute;
   162 
   163 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   164 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   165 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   166 
   167 * Pure: method 'atomize' presents local goal premises as object-level
   168 statements (atomic meta-level propositions); setup controlled via
   169 rewrite rules declarations of 'atomize' attribute; example
   170 application: 'induct' method with proper rule statements in improper
   171 proof *scripts*;
   172 
   173 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   174 now consider the syntactic context of assumptions, giving a better
   175 chance to get type-inference of the arguments right (this is
   176 especially important for locales);
   177 
   178 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   179 mode;
   180 
   181 * Pure/obtain: the formal conclusion "thesis", being marked as
   182 ``internal'', may no longer be reference directly in the text;
   183 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   184 situations;
   185 
   186 * Pure: generic 'sym' attribute which declares a rule both as pure
   187 'elim?' and for the 'symmetric' operation;
   188 
   189 * Pure: marginal comments ``--'' may now occur just anywhere in the
   190 text; the fixed correlation with particular command syntax has been
   191 discontinued;
   192 
   193 * Pure: new method 'rules' is particularly well-suited for proof
   194 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   195 but often produces more compact proof terms with less detours;
   196 
   197 * Pure/Provers/classical: simplified integration with pure rule
   198 attributes and methods; the classical "intro?/elim?/dest?"
   199 declarations coincide with the pure ones; the "rule" method no longer
   200 includes classically swapped intros; "intro" and "elim" methods no
   201 longer pick rules from the context; also got rid of ML declarations
   202 AddXIs/AddXEs/AddXDs; all of this has some potential for
   203 INCOMPATIBILITY;
   204 
   205 * Provers/classical: attribute 'swapped' produces classical inversions
   206 of introduction rules;
   207 
   208 * Provers/simplifier: 'simplified' attribute may refer to explicit
   209 rules instead of full simplifier context; 'iff' attribute handles
   210 conditional rules;
   211 
   212 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   213 
   214 * HOL: 'recdef' now fails on unfinished automated proofs, use
   215 "(permissive)" option to recover old behavior;
   216 
   217 * HOL: 'inductive' no longer features separate (collective) attributes
   218 for 'intros' (was found too confusing);
   219 
   220 * HOL: properly declared induction rules less_induct and
   221 wf_induct_rule;
   222 
   223 
   224 *** HOL ***
   225 
   226 * HOL: moved over to sane numeral syntax; the new policy is as
   227 follows:
   228 
   229   - 0 and 1 are polymorphic constants, which are defined on any
   230   numeric type (nat, int, real etc.);
   231 
   232   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   233   binary representation internally;
   234 
   235   - type nat has special constructor Suc, and generally prefers Suc 0
   236   over 1::nat and Suc (Suc 0) over 2::nat;
   237 
   238 This change may cause significant problems of INCOMPATIBILITY; here
   239 are some hints on converting existing sources:
   240 
   241   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   242   entities, so expressions involving "-" (unary or binary minus) need
   243   to be spaced properly;
   244 
   245   - existing occurrences of "1" may need to be constraint "1::nat" or
   246   even replaced by Suc 0; similar for old "2";
   247 
   248   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   249 
   250   - remove all special provisions on numerals in proofs;
   251 
   252 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   253 representation (depends on bin_arith_simps in the default context);
   254 
   255 * HOL: symbolic syntax for x^2 (numeral 2);
   256 
   257 * HOL: the class of all HOL types is now called "type" rather than
   258 "term"; INCOMPATIBILITY, need to adapt references to this type class
   259 in axclass/classes, instance/arities, and (usually rare) occurrences
   260 in typings (of consts etc.); internally the class is called
   261 "HOL.type", ML programs should refer to HOLogic.typeS;
   262 
   263 * HOL/record package improvements:
   264   - new derived operations "fields" to build a partial record section,
   265     "extend" to promote a fixed record to a record scheme, and
   266     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   267     declared as simp by default;
   268   - shared operations ("more", "fields", etc.) now need to be always
   269     qualified) --- potential INCOMPATIBILITY;
   270   - removed "make_scheme" operations (use "make" with "extend") --
   271     INCOMPATIBILITY;
   272   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   273   - provides cases/induct rules for use with corresponding Isar
   274     methods (for concrete records, record schemes, concrete more
   275     parts, and schematic more parts -- in that order);
   276   - internal definitions directly based on a light-weight abstract
   277     theory of product types over typedef rather than datatype;
   278 
   279 * HOL: generic code generator for generating executable ML code from
   280 specifications; specific support for HOL constructs such as inductive
   281 datatypes and sets, as well as recursive functions; can be invoked
   282 via 'generate_code' theory section;
   283 
   284 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   285 
   286 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   287 (beware of argument permutation!);
   288 
   289 * HOL: linorder_less_split superseded by linorder_cases;
   290 
   291 * HOL/List: "nodups" renamed to "distinct";
   292 
   293 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   294 to peripheral theory "Hilbert_Choice";
   295 
   296 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   297 in this (rare) case use:
   298 
   299   delSWrapper "split_all_tac"
   300   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   301 
   302 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   303 MAY FAIL;
   304 
   305 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   306 Isabelle's type classes, ^ on functions and relations has too general
   307 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   308 necessary to attach explicit type constraints;
   309 
   310 * HOL/Relation: the prefix name of the infix "O" has been changed from
   311 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   312 renamed accordingly (eg "compI" -> "rel_compI").
   313 
   314 * HOL: syntax translations now work properly with numerals and records
   315 expressions;
   316 
   317 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   318 of "lam" -- INCOMPATIBILITY;
   319 
   320 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   321 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   322 renamed "Product_Type.unit";
   323 
   324 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   325 
   326 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   327 the "cases" method);
   328 
   329 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   330 Florian Kammüller);
   331 
   332 * HOL/IMP: updated and converted to new-style theory format; several
   333 parts turned into readable document, with proper Isar proof texts and
   334 some explanations (by Gerwin Klein);
   335 
   336 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   337 
   338 * HOL-Hyperreal is now a logic image;
   339 
   340 
   341 *** HOLCF ***
   342 
   343 * Isar: consts/constdefs supports mixfix syntax for continuous
   344 operations;
   345 
   346 * Isar: domain package adapted to new-style theory format, e.g. see
   347 HOLCF/ex/Dnat.thy;
   348 
   349 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   350 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   351 lift.induct_tac, always use UU instead of Undef;
   352 
   353 * HOLCF/IMP: updated and converted to new-style theory;
   354 
   355 
   356 *** ZF ***
   357 
   358 * Isar: proper integration of logic-specific tools and packages,
   359 including theory commands '(co)inductive', '(co)datatype',
   360 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   361 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   362 
   363 * theory Main no longer includes AC; for the Axiom of Choice, base
   364 your theory on Main_ZFC;
   365 
   366 * the integer library now covers quotients and remainders, with many
   367 laws relating division to addition, multiplication, etc.;
   368 
   369 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   370 typeless version of the formalism;
   371 
   372 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   373 format;
   374 
   375 * ZF/Induct: new directory for examples of inductive definitions,
   376 including theory Multiset for multiset orderings; converted to
   377 new-style theory format;
   378 
   379 * ZF: many new theorems about lists, ordinals, etc.;
   380 
   381 
   382 *** General ***
   383 
   384 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   385 variable proof controls level of detail: 0 = no proofs (only oracle
   386 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   387 also ref manual for further ML interfaces;
   388 
   389 * Pure/axclass: removed obsolete ML interface
   390 goal_subclass/goal_arity;
   391 
   392 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   393 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   394 separate tokens, so expressions involving minus need to be spaced
   395 properly;
   396 
   397 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   398 rather than "infixl" or "infixr";
   399 
   400 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   401 sort constraint specifications in type inference; e.g. "x::_::foo"
   402 ensures that the type of "x" is of sort "foo" (but not necessarily a
   403 type variable);
   404 
   405 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   406 control output of nested => (types); the default behavior is
   407 "type_brackets";
   408 
   409 * Pure/syntax: builtin parse translation for "_constify" turns valued
   410 tokens into AST constants;
   411 
   412 * Pure/syntax: prefer later declarations of translations and print
   413 translation functions; potential INCOMPATIBILITY: need to reverse
   414 multiple declarations for same syntax element constant;
   415 
   416 * Pure/show_hyps reset by default (in accordance to existing Isar
   417 practice);
   418 
   419 * Provers/classical: renamed addaltern to addafter, addSaltern to
   420 addSafter;
   421 
   422 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   423 as well;
   424 
   425 * system: tested support for MacOS X; should be able to get Isabelle +
   426 Proof General to work in a plain Terminal after installing Poly/ML
   427 (e.g. from the Isabelle distribution area) and GNU bash alone
   428 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   429 support requires further installations, e.g. from
   430 http://fink.sourceforge.net/);
   431 
   432 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   433 
   434 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   435 of 40 MB), cf. ML_OPTIONS;
   436 
   437 * system: Proof General keywords specification is now part of the
   438 Isabelle distribution (see etc/isar-keywords.el);
   439 
   440 * system: support for persistent Proof General sessions (refrain from
   441 outdating all loaded theories on startup); user may create writable
   442 logic images like this: ``isabelle -q HOL Test'';
   443 
   444 * system: smart selection of Isabelle process versus Isabelle
   445 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   446 run both "isabelle" and "Isabelle" even if file names are badly
   447 damaged (executable inspects the case of the first letter of its own
   448 name); added separate "isabelle-process" and "isabelle-interface";
   449 
   450 * system: refrain from any attempt at filtering input streams; no
   451 longer support ``8bit'' encoding of old isabelle font, instead proper
   452 iso-latin characters may now be used; the related isatools
   453 "symbolinput" and "nonascii" have disappeared as well;
   454 
   455 * system: removed old "xterm" interface (the print modes "xterm" and
   456 "xterm_color" are still available for direct use in a suitable
   457 terminal);
   458 
   459 
   460 
   461 New in Isabelle99-2 (February 2001)
   462 -----------------------------------
   463 
   464 *** Overview of INCOMPATIBILITIES ***
   465 
   466 * HOL: please note that theories in the Library and elsewhere often use the
   467 new-style (Isar) format; to refer to their theorems in an ML script you must
   468 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   469 
   470 * HOL: inductive package no longer splits induction rule aggressively,
   471 but only as far as specified by the introductions given; the old
   472 format may be recovered via ML function complete_split_rule or attribute
   473 'split_rule (complete)';
   474 
   475 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   476 gfp_Tarski to gfp_unfold;
   477 
   478 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   479 
   480 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   481 relation); infix "^^" has been renamed "``"; infix "``" has been
   482 renamed "`"; "univalent" has been renamed "single_valued";
   483 
   484 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   485 operation;
   486 
   487 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   488 
   489 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   490 
   491 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   492 consequence, it is no longer monotonic wrt. the local goal context
   493 (which is now passed through the inductive cases);
   494 
   495 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   496 \<gg> to \<ggreater>;
   497 
   498 
   499 *** Document preparation ***
   500 
   501 * \isabellestyle{NAME} selects version of Isabelle output (currently
   502 available: are "it" for near math-mode best-style output, "sl" for
   503 slanted text style, and "tt" for plain type-writer; if no
   504 \isabellestyle command is given, output is according to slanted
   505 type-writer);
   506 
   507 * support sub/super scripts (for single symbols only), input syntax is
   508 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   509 
   510 * some more standard symbols; see Appendix A of the system manual for
   511 the complete list of symbols defined in isabellesym.sty;
   512 
   513 * improved isabelle style files; more abstract symbol implementation
   514 (should now use \isamath{...} and \isatext{...} in custom symbol
   515 definitions);
   516 
   517 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   518 state; Note that presentation of goal states does not conform to
   519 actual human-readable proof documents.  Please do not include goal
   520 states into document output unless you really know what you are doing!
   521 
   522 * proper indentation of antiquoted output with proportional LaTeX
   523 fonts;
   524 
   525 * no_document ML operator temporarily disables LaTeX document
   526 generation;
   527 
   528 * isatool unsymbolize tunes sources for plain ASCII communication;
   529 
   530 
   531 *** Isar ***
   532 
   533 * Pure: Isar now suffers initial goal statements to contain unbound
   534 schematic variables (this does not conform to actual readable proof
   535 documents, due to unpredictable outcome and non-compositional proof
   536 checking); users who know what they are doing may use schematic goals
   537 for Prolog-style synthesis of proven results;
   538 
   539 * Pure: assumption method (an implicit finishing) now handles actual
   540 rules as well;
   541 
   542 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   543 initial goal, declare "that" only as Pure intro (only for single
   544 steps); the "that" rule assumption may now be involved in implicit
   545 finishing, thus ".." becomes a feasible for trivial obtains;
   546 
   547 * Pure: default proof step now includes 'intro_classes'; thus trivial
   548 instance proofs may be performed by "..";
   549 
   550 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   551 statements as well;
   552 
   553 * Pure: more robust selection of calculational rules;
   554 
   555 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   556 rule (as well as the assumption rule);
   557 
   558 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   559 lemmas, using the graph browser tool;
   560 
   561 * Pure: predict failure of "show" in interactive mode;
   562 
   563 * Pure: 'thms_containing' now takes actual terms as arguments;
   564 
   565 * HOL: improved method 'induct' --- now handles non-atomic goals
   566 (potential INCOMPATIBILITY); tuned error handling;
   567 
   568 * HOL: cases and induct rules now provide explicit hints about the
   569 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   570 any remaining facts are inserted into the goal verbatim;
   571 
   572 * HOL: local contexts (aka cases) may now contain term bindings as
   573 well; the 'cases' and 'induct' methods new provide a ?case binding for
   574 the result to be shown in each case;
   575 
   576 * HOL: added 'recdef_tc' command;
   577 
   578 * isatool convert assists in eliminating legacy ML scripts;
   579 
   580 
   581 *** HOL ***
   582 
   583 * HOL/Library: a collection of generic theories to be used together
   584 with main HOL; the theory loader path already includes this directory
   585 by default; the following existing theories have been moved here:
   586 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   587 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   588 
   589 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   590 modelling and verification task performed in Isabelle/HOL +
   591 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   592 
   593 * HOL/Algebra: special summation operator SUM no longer exists, it has
   594 been replaced by setsum; infix 'assoc' now has priority 50 (like
   595 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   596 'domain', this makes the theory consistent with mathematical
   597 literature;
   598 
   599 * HOL basics: added overloaded operations "inverse" and "divide"
   600 (infix "/"), syntax for generic "abs" operation, generic summation
   601 operator \<Sum>;
   602 
   603 * HOL/typedef: simplified package, provide more useful rules (see also
   604 HOL/subset.thy);
   605 
   606 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   607 now expressed as a proper nested rule (old-style tactic scripts may
   608 require atomize_strip_tac to cope with non-atomic premises);
   609 
   610 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   611 to "split_conv" (old name still available for compatibility);
   612 
   613 * HOL: improved concrete syntax for strings (e.g. allows translation
   614 rules with string literals);
   615 
   616 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   617  and Fleuriot's mechanization of analysis, including the transcendental
   618  functions for the reals;
   619 
   620 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   621 
   622 
   623 *** CTT ***
   624 
   625 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   626 "lam" is displayed as TWO lambda-symbols
   627 
   628 * CTT: theory Main now available, containing everything (that is, Bool
   629 and Arith);
   630 
   631 
   632 *** General ***
   633 
   634 * Pure: the Simplifier has been implemented properly as a derived rule
   635 outside of the actual kernel (at last!); the overall performance
   636 penalty in practical applications is about 50%, while reliability of
   637 the Isabelle inference kernel has been greatly improved;
   638 
   639 * print modes "brackets" and "no_brackets" control output of nested =>
   640 (types) and ==> (props); the default behaviour is "brackets";
   641 
   642 * Provers: fast_tac (and friends) now handle actual object-logic rules
   643 as assumptions as well;
   644 
   645 * system: support Poly/ML 4.0;
   646 
   647 * system: isatool install handles KDE version 1 or 2;
   648 
   649 
   650 
   651 New in Isabelle99-1 (October 2000)
   652 ----------------------------------
   653 
   654 *** Overview of INCOMPATIBILITIES ***
   655 
   656 * HOL: simplification of natural numbers is much changed; to partly
   657 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   658 issue the following ML commands:
   659 
   660   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   661   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   662 
   663 * HOL: simplification no longer dives into case-expressions; this is
   664 controlled by "t.weak_case_cong" for each datatype t;
   665 
   666 * HOL: nat_less_induct renamed to less_induct;
   667 
   668 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   669 fixsome to patch .thy and .ML sources automatically;
   670 
   671   select_equality  -> some_equality
   672   select_eq_Ex     -> some_eq_ex
   673   selectI2EX       -> someI2_ex
   674   selectI2         -> someI2
   675   selectI          -> someI
   676   select1_equality -> some1_equality
   677   Eps_sym_eq       -> some_sym_eq_trivial
   678   Eps_eq           -> some_eq_trivial
   679 
   680 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   681 
   682 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   683 instead);
   684 
   685 * HOL: the recursion equations generated by 'recdef' are now called
   686 f.simps instead of f.rules;
   687 
   688 * HOL: qed_spec_mp now also handles bounded ALL as well;
   689 
   690 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   691 sometimes be needed;
   692 
   693 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   694 
   695 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   696 
   697 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   698 product is now "<*>" instead of "Times"; the lexicographic product is
   699 now "<*lex*>" instead of "**";
   700 
   701 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   702 of main HOL, but was unused); better use HOL's datatype package;
   703 
   704 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   705 the old syntax may be recovered as follows:
   706 
   707   syntax (symbols)
   708     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   709       (infixl "\\<oplus>" 100)
   710 
   711 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   712 
   713 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   714 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   715 internally;
   716 
   717 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   718 changed from A/r to A//r;
   719 
   720 * ZF: new treatment of arithmetic (nat & int) may break some old
   721 proofs;
   722 
   723 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   724 rulify -> rule_format, elimify -> elim_format, ...);
   725 
   726 * Isar/Provers: intro/elim/dest attributes changed; renamed
   727 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   728 should have to change intro!! to intro? only); replaced "delrule" by
   729 "rule del";
   730 
   731 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   732 
   733 * Provers: strengthened force_tac by using new first_best_tac;
   734 
   735 * LaTeX document preparation: several changes of isabelle.sty (see
   736 lib/texinputs);
   737 
   738 
   739 *** Document preparation ***
   740 
   741 * formal comments (text blocks etc.) in new-style theories may now
   742 contain antiquotations of thm/prop/term/typ/text to be presented
   743 according to latex print mode; concrete syntax is like this:
   744 @{term[show_types] "f(x) = a + x"};
   745 
   746 * isatool mkdir provides easy setup of Isabelle session directories,
   747 including proper document sources;
   748 
   749 * generated LaTeX sources are now deleted after successful run
   750 (isatool document -c); may retain a copy somewhere else via -D option
   751 of isatool usedir;
   752 
   753 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   754 style files, achieving self-contained LaTeX sources and simplifying
   755 LaTeX debugging;
   756 
   757 * old-style theories now produce (crude) LaTeX output as well;
   758 
   759 * browser info session directories are now self-contained (may be put
   760 on WWW server seperately); improved graphs of nested sessions; removed
   761 graph for 'all sessions';
   762 
   763 * several improvements in isabelle style files; \isabellestyle{it}
   764 produces fake math mode output; \isamarkupheader is now \section by
   765 default; see lib/texinputs/isabelle.sty etc.;
   766 
   767 
   768 *** Isar ***
   769 
   770 * Isar/Pure: local results and corresponding term bindings are now
   771 subject to Hindley-Milner polymorphism (similar to ML); this
   772 accommodates incremental type-inference very nicely;
   773 
   774 * Isar/Pure: new derived language element 'obtain' supports
   775 generalized existence reasoning;
   776 
   777 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   778 support accumulation of results, without applying any rules yet;
   779 useful to collect intermediate results without explicit name
   780 references, and for use with transitivity rules with more than 2
   781 premises;
   782 
   783 * Isar/Pure: scalable support for case-analysis type proofs: new
   784 'case' language element refers to local contexts symbolically, as
   785 produced by certain proof methods; internally, case names are attached
   786 to theorems as "tags";
   787 
   788 * Isar/Pure: theory command 'hide' removes declarations from
   789 class/type/const name spaces;
   790 
   791 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   792 indicate potential overloading;
   793 
   794 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   795 
   796 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   797 "{a,b,c}" instead of {a,b,c};
   798 
   799 * Isar/Pure now provides its own version of intro/elim/dest
   800 attributes; useful for building new logics, but beware of confusion
   801 with the version in Provers/classical;
   802 
   803 * Isar/Pure: the local context of (non-atomic) goals is provided via
   804 case name 'antecedent';
   805 
   806 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   807 to the current context is now done automatically);
   808 
   809 * Isar/Pure: theory command 'method_setup' provides a simple interface
   810 for definining proof methods in ML;
   811 
   812 * Isar/Provers: intro/elim/dest attributes changed; renamed
   813 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   814 most cases, one should have to change intro!! to intro? only);
   815 replaced "delrule" by "rule del";
   816 
   817 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   818 'symmetric' attribute (the latter supercedes [RS sym]);
   819 
   820 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   821 method modifier); 'simp' method: 'only:' modifier removes loopers as
   822 well (including splits);
   823 
   824 * Isar/Provers: Simplifier and Classical methods now support all kind
   825 of modifiers used in the past, including 'cong', 'iff', etc.
   826 
   827 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   828 of Simplifier and Classical reasoner);
   829 
   830 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   831 now support named cases; major packages (inductive, datatype, primrec,
   832 recdef) support case names and properly name parameters;
   833 
   834 * Isar/HOL: new transitivity rules for substitution in inequalities --
   835 monotonicity conditions are extracted to be proven at end of
   836 calculations;
   837 
   838 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   839 method anyway;
   840 
   841 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   842 split_if split_if_asm; datatype package provides theorems foo.splits =
   843 foo.split foo.split_asm for each datatype;
   844 
   845 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   846 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   847 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   848 use "(cases (simplified))" method in proper proof texts);
   849 
   850 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   851 
   852 * Isar: names of theorems etc. may be natural numbers as well;
   853 
   854 * Isar: 'pr' command: optional arguments for goals_limit and
   855 ProofContext.prems_limit; no longer prints theory contexts, but only
   856 proof states;
   857 
   858 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   859 additional print modes to be specified; e.g. "pr(latex)" will print
   860 proof state according to the Isabelle LaTeX style;
   861 
   862 * Isar: improved support for emulating tactic scripts, including proof
   863 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   864 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   865 (for HOL datatypes);
   866 
   867 * Isar: simplified (more robust) goal selection of proof methods: 1st
   868 goal, all goals, or explicit goal specifier (tactic emulation); thus
   869 'proof method scripts' have to be in depth-first order;
   870 
   871 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   872 
   873 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   874 should instead use individual commands for printing items
   875 (print_commands, print_methods etc.);
   876 
   877 * Isar: added 'nothing' --- the empty list of theorems;
   878 
   879 
   880 *** HOL ***
   881 
   882 * HOL/MicroJava: formalization of a fragment of Java, together with a
   883 corresponding virtual machine and a specification of its bytecode
   884 verifier and a lightweight bytecode verifier, including proofs of
   885 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   886 Cornelia Pusch (see also the homepage of project Bali at
   887 http://isabelle.in.tum.de/Bali/);
   888 
   889 * HOL/Algebra: new theory of rings and univariate polynomials, by
   890 Clemens Ballarin;
   891 
   892 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   893 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   894 Rasmussen;
   895 
   896 * HOL/Lattice: fundamental concepts of lattice theory and order
   897 structures, including duals, properties of bounds versus algebraic
   898 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   899 Theorem for complete lattices etc.; may also serve as a demonstration
   900 for abstract algebraic reasoning using axiomatic type classes, and
   901 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   902 
   903 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   904 von Oheimb;
   905 
   906 * HOL/IMPP: extension of IMP with local variables and mutually
   907 recursive procedures, by David von Oheimb;
   908 
   909 * HOL/Lambda: converted into new-style theory and document;
   910 
   911 * HOL/ex/Multiquote: example of multiple nested quotations and
   912 anti-quotations -- basically a generalized version of de-Bruijn
   913 representation; very useful in avoiding lifting of operations;
   914 
   915 * HOL/record: added general record equality rule to simpset; fixed
   916 select-update simplification procedure to handle extended records as
   917 well; admit "r" as field name;
   918 
   919 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   920 other numeric types and also as the identity of groups, rings, etc.;
   921 
   922 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   923 Types nat and int belong to this axclass;
   924 
   925 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   926    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   927    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   928   two terms #m*u and #n*u are replaced by #(m+n)*u
   929     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   930   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   931     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   932 
   933 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   934 powerful prover for predicate logic but knows nothing of clasets; see
   935 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   936 
   937 * HOL: new version of "case_tac" subsumes both boolean case split and
   938 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   939 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   940 
   941 * HOL: simplification no longer dives into case-expressions: only the
   942 selector expression is simplified, but not the remaining arms; to
   943 enable full simplification of case-expressions for datatype t, you may
   944 remove t.weak_case_cong from the simpset, either globally (Delcongs
   945 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   946 
   947 * HOL/recdef: the recursion equations generated by 'recdef' for
   948 function 'f' are now called f.simps instead of f.rules; if all
   949 termination conditions are proved automatically, these simplification
   950 rules are added to the simpset, as in primrec; rules may be named
   951 individually as well, resulting in a separate list of theorems for
   952 each equation;
   953 
   954 * HOL/While is a new theory that provides a while-combinator. It
   955 permits the definition of tail-recursive functions without the
   956 provision of a termination measure. The latter is necessary once the
   957 invariant proof rule for while is applied.
   958 
   959 * HOL: new (overloaded) notation for the set of elements below/above
   960 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   961 
   962 * HOL: theorems impI, allI, ballI bound as "strip";
   963 
   964 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   965 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   966 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   967 
   968 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   969 
   970 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   971 main HOL, but was unused);
   972 
   973 * HOL: fewer consts declared as global (e.g. have to refer to
   974 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   975 
   976 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   977 in case of overlap with user translations (e.g. judgements over
   978 tuples); (note that the underlying logical represenation is still
   979 bogus);
   980 
   981 
   982 *** ZF ***
   983 
   984 * ZF: simplification automatically cancels common terms in arithmetic
   985 expressions over nat and int;
   986 
   987 * ZF: new treatment of nat to minimize type-checking: all operators
   988 coerce their operands to a natural number using the function natify,
   989 making the algebraic laws unconditional;
   990 
   991 * ZF: as above, for int: operators coerce their operands to an integer
   992 using the function intify;
   993 
   994 * ZF: the integer library now contains many of the usual laws for the
   995 orderings, including $<=, and monotonicity laws for $+ and $*;
   996 
   997 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
   998 simplification;
   999 
  1000 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1001 to the simplifier and classical reasoner simultaneously;
  1002 
  1003 
  1004 *** General ***
  1005 
  1006 * Provers: blast_tac now handles actual object-logic rules as
  1007 assumptions; note that auto_tac uses blast_tac internally as well;
  1008 
  1009 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1010 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1011 
  1012 * Provers: delrules now handles destruct rules as well (no longer need
  1013 explicit make_elim);
  1014 
  1015 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1016   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1017 use instead the strong form,
  1018   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1019 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1020 from destruct-rules;
  1021 
  1022 * Provers: Simplifier.easy_setup provides a fast path to basic
  1023 Simplifier setup for new object-logics;
  1024 
  1025 * Pure: AST translation rules no longer require constant head on LHS;
  1026 
  1027 * Pure: improved name spaces: ambiguous output is qualified; support
  1028 for hiding of names;
  1029 
  1030 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1031 XSYMBOL_HOME; no longer need to do manual configuration in most
  1032 situations;
  1033 
  1034 * system: compression of ML heaps images may now be controlled via -c
  1035 option of isabelle and isatool usedir (currently only observed by
  1036 Poly/ML);
  1037 
  1038 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1039 useful for remote X11);
  1040 
  1041 * system: provide TAGS file for Isabelle sources;
  1042 
  1043 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1044 order;
  1045 
  1046 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1047 timing flag supersedes proof_timing and Toplevel.trace;
  1048 
  1049 * ML: new combinators |>> and |>>> for incremental transformations
  1050 with secondary results (e.g. certain theory extensions):
  1051 
  1052 * ML: PureThy.add_defs gets additional argument to indicate potential
  1053 overloading (usually false);
  1054 
  1055 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1056 results;
  1057 
  1058 
  1059 
  1060 New in Isabelle99 (October 1999)
  1061 --------------------------------
  1062 
  1063 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1064 
  1065 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1066 are no longer simplified.  (This allows the simplifier to unfold recursive
  1067 functional programs.)  To restore the old behaviour, declare
  1068 
  1069     Delcongs [if_weak_cong];
  1070 
  1071 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1072 complement;
  1073 
  1074 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1075 
  1076 * HOL/datatype: mutual_induct_tac no longer exists --
  1077   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1078 
  1079 * HOL/typedef: fixed type inference for representing set; type
  1080 arguments now have to occur explicitly on the rhs as type constraints;
  1081 
  1082 * ZF: The con_defs part of an inductive definition may no longer refer
  1083 to constants declared in the same theory;
  1084 
  1085 * HOL, ZF: the function mk_cases, generated by the inductive
  1086 definition package, has lost an argument.  To simplify its result, it
  1087 uses the default simpset instead of a supplied list of theorems.
  1088 
  1089 * HOL/List: the constructors of type list are now Nil and Cons;
  1090 
  1091 * Simplifier: the type of the infix ML functions
  1092         setSSolver addSSolver setSolver addSolver
  1093 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1094 for packaging solvers. A solver is created via
  1095         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1096 where the string argument is only a comment.
  1097 
  1098 
  1099 *** Proof tools ***
  1100 
  1101 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1102 decision procedure for linear arithmetic. Currently it is used for
  1103 types `nat', `int', and `real' in HOL (see below); it can, should and
  1104 will be instantiated for other types and logics as well.
  1105 
  1106 * The simplifier now accepts rewrite rules with flexible heads, eg
  1107      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1108   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1109   matching.
  1110 
  1111 
  1112 *** General ***
  1113 
  1114 * New Isabelle/Isar subsystem provides an alternative to traditional
  1115 tactical theorem proving; together with the ProofGeneral/isar user
  1116 interface it offers an interactive environment for developing human
  1117 readable proof documents (Isar == Intelligible semi-automated
  1118 reasoning); for further information see isatool doc isar-ref,
  1119 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1120 
  1121 * improved and simplified presentation of theories: better HTML markup
  1122 (including colors), graph views in several sizes; isatool usedir now
  1123 provides a proper interface for user theories (via -P option); actual
  1124 document preparation based on (PDF)LaTeX is available as well (for
  1125 new-style theories only); see isatool doc system for more information;
  1126 
  1127 * native support for Proof General, both for classic Isabelle and
  1128 Isabelle/Isar;
  1129 
  1130 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1131 using the graph browser tool;
  1132 
  1133 * Isabelle manuals now also available as PDF;
  1134 
  1135 * theory loader rewritten from scratch (may not be fully
  1136 bug-compatible); old loadpath variable has been replaced by show_path,
  1137 add_path, del_path, reset_path functions; new operations such as
  1138 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1139 isatool doc ref);
  1140 
  1141 * improved isatool install: option -k creates KDE application icon,
  1142 option -p DIR installs standalone binaries;
  1143 
  1144 * added ML_PLATFORM setting (useful for cross-platform installations);
  1145 more robust handling of platform specific ML images for SML/NJ;
  1146 
  1147 * the settings environment is now statically scoped, i.e. it is never
  1148 created again in sub-processes invoked from isabelle, isatool, or
  1149 Isabelle;
  1150 
  1151 * path element specification '~~' refers to '$ISABELLE_HOME';
  1152 
  1153 * in locales, the "assumes" and "defines" parts may be omitted if
  1154 empty;
  1155 
  1156 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1157 long arrows);
  1158 
  1159 * new print_mode "HTML";
  1160 
  1161 * new flag show_tags controls display of tags of theorems (which are
  1162 basically just comments that may be attached by some tools);
  1163 
  1164 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1165 mode and goal output format:
  1166 
  1167 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1168 244c244
  1169 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1170 ---
  1171 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1172 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1173 181c181
  1174 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1175 ---
  1176 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1177 
  1178 * function bind_thms stores lists of theorems (cf. bind_thm);
  1179 
  1180 * new shorthand tactics ftac, eatac, datac, fatac;
  1181 
  1182 * qed (and friends) now accept "" as result name; in that case the
  1183 theorem is not stored, but proper checks and presentation of the
  1184 result still apply;
  1185 
  1186 * theorem database now also indexes constants "Trueprop", "all",
  1187 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1188 
  1189 
  1190 *** HOL ***
  1191 
  1192 ** HOL arithmetic **
  1193 
  1194 * There are now decision procedures for linear arithmetic over nat and
  1195 int:
  1196 
  1197 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1198 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1199 are treated as atomic; subformulae not involving type `nat' or `int'
  1200 are ignored; quantified subformulae are ignored unless they are
  1201 positive universal or negative existential. The tactic has to be
  1202 invoked by hand and can be a little bit slow. In particular, the
  1203 running time is exponential in the number of occurrences of `min' and
  1204 `max', and `-' on `nat'.
  1205 
  1206 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1207 (negated) (in)equalities among the premises and the conclusion into
  1208 account (i.e. no compound formulae) and does not know about `min' and
  1209 `max', and `-' on `nat'. It is fast and is used automatically by the
  1210 simplifier.
  1211 
  1212 NB: At the moment, these decision procedures do not cope with mixed
  1213 nat/int formulae where the two parts interact, such as `m < n ==>
  1214 int(m) < int(n)'.
  1215 
  1216 * HOL/Numeral provides a generic theory of numerals (encoded
  1217 efficiently as bit strings); setup for types nat/int/real is in place;
  1218 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1219 int, existing theories and proof scripts may require a few additional
  1220 type constraints;
  1221 
  1222 * integer division and remainder can now be performed on constant
  1223 arguments;
  1224 
  1225 * many properties of integer multiplication, division and remainder
  1226 are now available;
  1227 
  1228 * An interface to the Stanford Validity Checker (SVC) is available through the
  1229 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1230 are proved automatically.  SVC must be installed separately, and its results
  1231 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1232 invocation of the underlying oracle).  For SVC see
  1233   http://verify.stanford.edu/SVC
  1234 
  1235 * IsaMakefile: the HOL-Real target now builds an actual image;
  1236 
  1237 
  1238 ** HOL misc **
  1239 
  1240 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1241 (in Isabelle/Isar) -- by Gertrud Bauer;
  1242 
  1243 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1244 analysis for assembly languages with subtypes;
  1245 
  1246 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1247 -- avoids syntactic ambiguities and treats state, transition, and
  1248 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1249 changed syntax and (many) tactics;
  1250 
  1251 * HOL/inductive: Now also handles more general introduction rules such
  1252   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1253   theorems are now maintained within the theory (maintained via the
  1254   "mono" attribute);
  1255 
  1256 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1257   (using function types) such as
  1258 
  1259   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1260 
  1261 * HOL/record: record_simproc (part of the default simpset) takes care
  1262 of selectors applied to updated records; record_split_tac is no longer
  1263 part of the default claset; update_defs may now be removed from the
  1264 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1265 
  1266   claset_ref () := claset() addSWrapper record_split_wrapper;
  1267   Delsimprocs [record_simproc]
  1268 
  1269 * HOL/typedef: fixed type inference for representing set; type
  1270 arguments now have to occur explicitly on the rhs as type constraints;
  1271 
  1272 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1273 names rather than an ML expression;
  1274 
  1275 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1276 supplied later.  Program schemes can be defined, such as
  1277     "While B C s = (if B s then While B C (C s) else s)"
  1278 where the well-founded relation can be chosen after B and C have been given.
  1279 
  1280 * HOL/List: the constructors of type list are now Nil and Cons;
  1281 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1282 course, ML tools referring to List.list.op # etc. have to be adapted;
  1283 
  1284 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1285 disabled by default; run isabelle with option -m HOL to get back to
  1286 the original Gordon/HOL-style output;
  1287 
  1288 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1289 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1290 
  1291 * HOL basic syntax simplified (more orthogonal): all variants of
  1292 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1293 Eps operator is provided as well: "SOME x. P[x]";
  1294 
  1295 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1296 
  1297 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1298 thus available for user theories;
  1299 
  1300 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1301 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1302 time;
  1303 
  1304 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1305 several times and then mp;
  1306 
  1307 
  1308 *** LK ***
  1309 
  1310 * the notation <<...>> is now available as a notation for sequences of
  1311 formulas;
  1312 
  1313 * the simplifier is now installed
  1314 
  1315 * the axiom system has been generalized (thanks to Soren Heilmann)
  1316 
  1317 * the classical reasoner now has a default rule database
  1318 
  1319 
  1320 *** ZF ***
  1321 
  1322 * new primrec section allows primitive recursive functions to be given
  1323 directly (as in HOL) over datatypes and the natural numbers;
  1324 
  1325 * new tactics induct_tac and exhaust_tac for induction (or case
  1326 analysis) over datatypes and the natural numbers;
  1327 
  1328 * the datatype declaration of type T now defines the recursor T_rec;
  1329 
  1330 * simplification automatically does freeness reasoning for datatype
  1331 constructors;
  1332 
  1333 * automatic type-inference, with AddTCs command to insert new
  1334 type-checking rules;
  1335 
  1336 * datatype introduction rules are now added as Safe Introduction rules
  1337 to the claset;
  1338 
  1339 * the syntax "if P then x else y" is now available in addition to
  1340 if(P,x,y);
  1341 
  1342 
  1343 *** Internal programming interfaces ***
  1344 
  1345 * tuned simplifier trace output; new flag debug_simp;
  1346 
  1347 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1348 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1349 
  1350 * AxClass.axclass_tac lost the theory argument;
  1351 
  1352 * tuned current_goals_markers semantics: begin / end goal avoids
  1353 printing empty lines;
  1354 
  1355 * removed prs and prs_fn hook, which was broken because it did not
  1356 include \n in its semantics, forcing writeln to add one
  1357 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1358 string -> unit if you really want to output text without newline;
  1359 
  1360 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1361 plain output, interface builders may have to enable 'isabelle_font'
  1362 mode to get Isabelle font glyphs as before;
  1363 
  1364 * refined token_translation interface; INCOMPATIBILITY: output length
  1365 now of type real instead of int;
  1366 
  1367 * theory loader actions may be traced via new ThyInfo.add_hook
  1368 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1369 your own database of information attached to *whole* theories -- as
  1370 opposed to intra-theory data slots offered via TheoryDataFun;
  1371 
  1372 * proper handling of dangling sort hypotheses (at last!);
  1373 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1374 extra sort hypotheses that can be witnessed from the type signature;
  1375 the force_strip_shyps flag is gone, any remaining shyps are simply
  1376 left in the theorem (with a warning issued by strip_shyps_warning);
  1377 
  1378 
  1379 
  1380 New in Isabelle98-1 (October 1998)
  1381 ----------------------------------
  1382 
  1383 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1384 
  1385 * several changes of automated proof tools;
  1386 
  1387 * HOL: major changes to the inductive and datatype packages, including
  1388 some minor incompatibilities of theory syntax;
  1389 
  1390 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1391 called `inj_on';
  1392 
  1393 * HOL: removed duplicate thms in Arith:
  1394   less_imp_add_less  should be replaced by  trans_less_add1
  1395   le_imp_add_le      should be replaced by  trans_le_add1
  1396 
  1397 * HOL: unary minus is now overloaded (new type constraints may be
  1398 required);
  1399 
  1400 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1401 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1402 now taken as an integer constant.
  1403 
  1404 * Pure: ML function 'theory_of' renamed to 'theory';
  1405 
  1406 
  1407 *** Proof tools ***
  1408 
  1409 * Simplifier:
  1410   1. Asm_full_simp_tac is now more aggressive.
  1411      1. It will sometimes reorient premises if that increases their power to
  1412         simplify.
  1413      2. It does no longer proceed strictly from left to right but may also
  1414         rotate premises to achieve further simplification.
  1415      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1416      old Asm_full_simp_tac in that it does not rotate premises.
  1417   2. The simplifier now knows a little bit about nat-arithmetic.
  1418 
  1419 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1420 allows for selected deletion of wrappers, by introduction of names for
  1421 wrapper functionals.  This implies that addbefore, addSbefore,
  1422 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1423 and that adding two tactics with the same name overwrites the first
  1424 one (emitting a warning).
  1425   type wrapper = (int -> tactic) -> (int -> tactic)
  1426   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1427   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1428   delWrapper, delSWrapper: claset *  string            -> claset
  1429   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1430 
  1431 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1432 semantics; addbefore now affects only the unsafe part of step_tac
  1433 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1434 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1435 by Force_tac;
  1436 
  1437 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1438 compWrapper; added safe wrapper (and access functions for it);
  1439 
  1440 * HOL/split_all_tac is now much faster and fails if there is nothing
  1441 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1442 and the names of the automatically generated variables have changed.
  1443 split_all_tac has moved within claset() from unsafe wrappers to safe
  1444 wrappers, which means that !!-bound variables are split much more
  1445 aggressively, and safe_tac and clarify_tac now split such variables.
  1446 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1447 Note: the same holds for record_split_tac, which does the job of
  1448 split_all_tac for record fields.
  1449 
  1450 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1451 permanently to the default simpset using Addsplits just like
  1452 Addsimps. They can be removed via Delsplits just like
  1453 Delsimps. Lower-case versions are also available.
  1454 
  1455 * HOL/Simplifier: The rule split_if is now part of the default
  1456 simpset. This means that the simplifier will eliminate all occurrences
  1457 of if-then-else in the conclusion of a goal. To prevent this, you can
  1458 either remove split_if completely from the default simpset by
  1459 `Delsplits [split_if]' or remove it in a specific call of the
  1460 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1461 other case splitting rules to/from the default simpset: every datatype
  1462 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1463 t is the name of the datatype).
  1464 
  1465 * Classical reasoner / Simplifier combination: new force_tac (and
  1466 derivatives Force_tac, force) combines rewriting and classical
  1467 reasoning (and whatever other tools) similarly to auto_tac, but is
  1468 aimed to solve the given subgoal completely.
  1469 
  1470 
  1471 *** General ***
  1472 
  1473 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1474 and `goalw': the theory is no longer needed as an explicit argument -
  1475 the current theory context is used; assumptions are no longer returned
  1476 at the ML-level unless one of them starts with ==> or !!; it is
  1477 recommended to convert to these new commands using isatool fixgoal
  1478 (backup your sources first!);
  1479 
  1480 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1481 the current theory context, and 'theory' to lookup stored theories;
  1482 
  1483 * new theory section 'locale' for declaring constants, assumptions and
  1484 definitions that have local scope;
  1485 
  1486 * new theory section 'nonterminals' for purely syntactic types;
  1487 
  1488 * new theory section 'setup' for generic ML setup functions
  1489 (e.g. package initialization);
  1490 
  1491 * the distribution now includes Isabelle icons: see
  1492 lib/logo/isabelle-{small,tiny}.xpm;
  1493 
  1494 * isatool install - install binaries with absolute references to
  1495 ISABELLE_HOME/bin;
  1496 
  1497 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1498 
  1499 * print mode 'emacs' reserved for Isamode;
  1500 
  1501 * support multiple print (ast) translations per constant name;
  1502 
  1503 * theorems involving oracles are now printed with a suffixed [!];
  1504 
  1505 
  1506 *** HOL ***
  1507 
  1508 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1509 
  1510 * HOL/inductive package reorganized and improved: now supports mutual
  1511 definitions such as
  1512 
  1513   inductive EVEN ODD
  1514     intrs
  1515       null "0 : EVEN"
  1516       oddI "n : EVEN ==> Suc n : ODD"
  1517       evenI "n : ODD ==> Suc n : EVEN"
  1518 
  1519 new theorem list "elims" contains an elimination rule for each of the
  1520 recursive sets; inductive definitions now handle disjunctive premises
  1521 correctly (also ZF);
  1522 
  1523 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1524 "mutual_induct" no longer exists - the induction rule is always
  1525 contained in "induct";
  1526 
  1527 
  1528 * HOL/datatype package re-implemented and greatly improved: now
  1529 supports mutually recursive datatypes such as
  1530 
  1531   datatype
  1532     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1533             | SUM ('a aexp) ('a aexp)
  1534             | DIFF ('a aexp) ('a aexp)
  1535             | NUM 'a
  1536   and
  1537     'a bexp = LESS ('a aexp) ('a aexp)
  1538             | AND ('a bexp) ('a bexp)
  1539             | OR ('a bexp) ('a bexp)
  1540 
  1541 as well as indirectly recursive datatypes such as
  1542 
  1543   datatype
  1544     ('a, 'b) term = Var 'a
  1545                   | App 'b ((('a, 'b) term) list)
  1546 
  1547 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1548 induction on mutually / indirectly recursive datatypes.
  1549 
  1550 Primrec equations are now stored in theory and can be accessed via
  1551 <function_name>.simps.
  1552 
  1553 INCOMPATIBILITIES:
  1554 
  1555   - Theories using datatypes must now have theory Datatype as an
  1556     ancestor.
  1557   - The specific <typename>.induct_tac no longer exists - use the
  1558     generic induct_tac instead.
  1559   - natE has been renamed to nat.exhaust - use exhaust_tac
  1560     instead of res_inst_tac ... natE. Note that the variable
  1561     names in nat.exhaust differ from the names in natE, this
  1562     may cause some "fragile" proofs to fail.
  1563   - The theorems split_<typename>_case and split_<typename>_case_asm
  1564     have been renamed to <typename>.split and <typename>.split_asm.
  1565   - Since default sorts of type variables are now handled correctly,
  1566     some datatype definitions may have to be annotated with explicit
  1567     sort constraints.
  1568   - Primrec definitions no longer require function name and type
  1569     of recursive argument.
  1570 
  1571 Consider using isatool fixdatatype to adapt your theories and proof
  1572 scripts to the new package (backup your sources first!).
  1573 
  1574 
  1575 * HOL/record package: considerably improved implementation; now
  1576 includes concrete syntax for record types, terms, updates; theorems
  1577 for surjective pairing and splitting !!-bound record variables; proof
  1578 support is as follows:
  1579 
  1580   1) standard conversions (selectors or updates applied to record
  1581 constructor terms) are part of the standard simpset;
  1582 
  1583   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1584 made part of standard simpset and claset via addIffs;
  1585 
  1586   3) a tactic for record field splitting (record_split_tac) is part of
  1587 the standard claset (addSWrapper);
  1588 
  1589 To get a better idea about these rules you may retrieve them via
  1590 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1591 the name of your record type.
  1592 
  1593 The split tactic 3) conceptually simplifies by the following rule:
  1594 
  1595   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1596 
  1597 Thus any record variable that is bound by meta-all will automatically
  1598 blow up into some record constructor term, consequently the
  1599 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1600 solve record problems automatically.
  1601 
  1602 
  1603 * reorganized the main HOL image: HOL/Integ and String loaded by
  1604 default; theory Main includes everything;
  1605 
  1606 * automatic simplification of integer sums and comparisons, using cancellation;
  1607 
  1608 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1609 
  1610 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1611 
  1612 * many new identities for unions, intersections, set difference, etc.;
  1613 
  1614 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1615 called split_if, split_split, split_sum_case and split_nat_case (to go
  1616 with add/delsplits);
  1617 
  1618 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1619 (?x::unit) = (); this is made part of the default simpset, which COULD
  1620 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1621 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1622 unit_abs_eta_conv is added in order to counter the effect of
  1623 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1624 %u.f();
  1625 
  1626 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1627 makes more sense);
  1628 
  1629 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1630   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1631   disjointness reasoning but breaking a few old proofs.
  1632 
  1633 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1634 to 'converse' from 'inverse' (for compatibility with ZF and some
  1635 literature);
  1636 
  1637 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1638 the well-founded relation;
  1639 
  1640 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1641     Compl A.  The "Compl" syntax remains available as input syntax for this
  1642     release ONLY.
  1643 
  1644 * HOL/Update: new theory of function updates:
  1645     f(a:=b) == %x. if x=a then b else f x
  1646 may also be iterated as in f(a:=b,c:=d,...);
  1647 
  1648 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1649 
  1650 * HOL/List:
  1651   - new function list_update written xs[i:=v] that updates the i-th
  1652     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1653   - new function `upt' written [i..j(] which generates the list
  1654     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1655     bound write [i..j], which is a shorthand for [i..j+1(].
  1656   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1657 
  1658 * HOL/Arith:
  1659   - removed 'pred' (predecessor) function;
  1660   - generalized some theorems about n-1;
  1661   - many new laws about "div" and "mod";
  1662   - new laws about greatest common divisors (see theory ex/Primes);
  1663 
  1664 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1665 instead of "inverse";
  1666 
  1667 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1668   of the multiset ordering;
  1669 
  1670 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1671   (not included by default);
  1672 
  1673 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1674 
  1675 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1676   programs, i.e. different program variables may have different types.
  1677 
  1678 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1679   [previously, this check worked only if the rewrite rule was unconditional]
  1680   Now rew can involve either definitions or equalities (either == or =).
  1681 
  1682 
  1683 *** ZF ***
  1684 
  1685 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1686   only the theorems proved on ZF.ML;
  1687 
  1688 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1689   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1690   disjointness reasoning but breaking a few old proofs.
  1691 
  1692 * ZF/Update: new theory of function updates
  1693     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1694   may also be iterated as in f(a:=b,c:=d,...);
  1695 
  1696 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1697 
  1698 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1699   [previously, this check worked only if the rewrite rule was unconditional]
  1700   Now rew can involve either definitions or equalities (either == or =).
  1701 
  1702 * case_tac provided for compatibility with HOL
  1703     (like the old excluded_middle_tac, but with subgoals swapped)
  1704 
  1705 
  1706 *** Internal programming interfaces ***
  1707 
  1708 * Pure: several new basic modules made available for general use, see
  1709 also src/Pure/README;
  1710 
  1711 * improved the theory data mechanism to support encapsulation (data
  1712 kind name replaced by private Object.kind, acting as authorization
  1713 key); new type-safe user interface via functor TheoryDataFun; generic
  1714 print_data function becomes basically useless;
  1715 
  1716 * removed global_names compatibility flag -- all theory declarations
  1717 are qualified by default;
  1718 
  1719 * module Pure/Syntax now offers quote / antiquote translation
  1720 functions (useful for Hoare logic etc. with implicit dependencies);
  1721 see HOL/ex/Antiquote for an example use;
  1722 
  1723 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1724 cterm -> thm;
  1725 
  1726 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1727 subgoal;
  1728 
  1729 * Display.print_goals function moved to Locale.print_goals;
  1730 
  1731 * standard print function for goals supports current_goals_markers
  1732 variable for marking begin of proof, end of proof, start of goal; the
  1733 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1734 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1735 for example;
  1736 
  1737 
  1738 
  1739 New in Isabelle98 (January 1998)
  1740 --------------------------------
  1741 
  1742 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1743 
  1744 * changed lexical syntax of terms / types: dots made part of long
  1745 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1746 
  1747 * simpset (and claset) reference variable replaced by functions
  1748 simpset / simpset_ref;
  1749 
  1750 * no longer supports theory aliases (via merge) and non-trivial
  1751 implicit merge of thms' signatures;
  1752 
  1753 * most internal names of constants changed due to qualified names;
  1754 
  1755 * changed Pure/Sequence interface (see Pure/seq.ML);
  1756 
  1757 
  1758 *** General Changes ***
  1759 
  1760 * hierachically structured name spaces (for consts, types, axms, thms
  1761 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1762 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1763 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1764 long_names for fully qualified output names; NOTE: ML programs
  1765 (special tactics, packages etc.) referring to internal names may have
  1766 to be adapted to cope with fully qualified names; in case of severe
  1767 backward campatibility problems try setting 'global_names' at compile
  1768 time to have enrything declared within a flat name space; one may also
  1769 fine tune name declarations in theories via the 'global' and 'local'
  1770 section;
  1771 
  1772 * reimplemented the implicit simpset and claset using the new anytype
  1773 data filed in signatures; references simpset:simpset ref etc. are
  1774 replaced by functions simpset:unit->simpset and
  1775 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1776 to patch your ML files accordingly;
  1777 
  1778 * HTML output now includes theory graph data for display with Java
  1779 applet or isatool browser; data generated automatically via isatool
  1780 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1781 
  1782 * defs may now be conditional; improved rewrite_goals_tac to handle
  1783 conditional equations;
  1784 
  1785 * defs now admits additional type arguments, using TYPE('a) syntax;
  1786 
  1787 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1788 creates a new theory node; implicit merge of thms' signatures is
  1789 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1790 transfer:theory->thm->thm in (rare) cases;
  1791 
  1792 * improved handling of draft signatures / theories; draft thms (and
  1793 ctyps, cterms) are automatically promoted to real ones;
  1794 
  1795 * slightly changed interfaces for oracles: admit many per theory, named
  1796 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1797 
  1798 * print_goals: optional output of const types (set show_consts and
  1799 show_types);
  1800 
  1801 * improved output of warnings (###) and errors (***);
  1802 
  1803 * subgoal_tac displays a warning if the new subgoal has type variables;
  1804 
  1805 * removed old README and Makefiles;
  1806 
  1807 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1808 
  1809 * removed obsolete init_pps and init_database;
  1810 
  1811 * deleted the obsolete tactical STATE, which was declared by
  1812     fun STATE tacfun st = tacfun st st;
  1813 
  1814 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1815 (which abbreviates $HOME);
  1816 
  1817 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1818 use isatool fixseq to adapt your ML programs (this works for fully
  1819 qualified references to the Sequence structure only!);
  1820 
  1821 * use_thy no longer requires writable current directory; it always
  1822 reloads .ML *and* .thy file, if either one is out of date;
  1823 
  1824 
  1825 *** Classical Reasoner ***
  1826 
  1827 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1828 tactics that use classical reasoning to simplify a subgoal without
  1829 splitting it into several subgoals;
  1830 
  1831 * Safe_tac: like safe_tac but uses the default claset;
  1832 
  1833 
  1834 *** Simplifier ***
  1835 
  1836 * added simplification meta rules:
  1837     (asm_)(full_)simplify: simpset -> thm -> thm;
  1838 
  1839 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1840 logics (again);
  1841 
  1842 * added prems argument to simplification procedures;
  1843 
  1844 * HOL, FOL, ZF: added infix function `addsplits':
  1845   instead of `<simpset> setloop (split_tac <thms>)'
  1846   you can simply write `<simpset> addsplits <thms>'
  1847 
  1848 
  1849 *** Syntax ***
  1850 
  1851 * TYPE('a) syntax for type reflection terms;
  1852 
  1853 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1854 
  1855 * pretty printer: changed order of mixfix annotation preference (again!);
  1856 
  1857 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1858 
  1859 
  1860 *** HOL ***
  1861 
  1862 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1863   with `addloop' of the simplifier to faciliate case splitting in premises.
  1864 
  1865 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1866 
  1867 * HOL/Auth: new protocol proofs including some for the Internet
  1868   protocol TLS;
  1869 
  1870 * HOL/Map: new theory of `maps' a la VDM;
  1871 
  1872 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1873 cancelling out common nat summands from =, <, <= (in)equalities, or
  1874 differences; simplification procedures nat_cancel_factor for
  1875 cancelling common factor from =, <, <= (in)equalities over natural
  1876 sums; nat_cancel contains both kinds of procedures, it is installed by
  1877 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1878 
  1879 * HOL/simplifier: terms of the form
  1880   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1881   are rewritten to
  1882   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1883   and those of the form
  1884   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1885   are rewritten to
  1886   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1887 
  1888 * HOL/datatype
  1889   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1890 
  1891   P(t_case f1 ... fn x) =
  1892      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1893         ...
  1894        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1895      )
  1896 
  1897   and a theorem `split_t_case_asm' of the form
  1898 
  1899   P(t_case f1 ... fn x) =
  1900     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1901         ...
  1902        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1903      )
  1904   which can be added to a simpset via `addsplits'. The existing theorems
  1905   expand_list_case and expand_option_case have been renamed to
  1906   split_list_case and split_option_case.
  1907 
  1908 * HOL/Arithmetic:
  1909   - `pred n' is automatically converted to `n-1'.
  1910     Users are strongly encouraged not to use `pred' any longer,
  1911     because it will disappear altogether at some point.
  1912   - Users are strongly encouraged to write "0 < n" rather than
  1913     "n ~= 0". Theorems and proof tools have been modified towards this
  1914     `standard'.
  1915 
  1916 * HOL/Lists:
  1917   the function "set_of_list" has been renamed "set" (and its theorems too);
  1918   the function "nth" now takes its arguments in the reverse order and
  1919   has acquired the infix notation "!" as in "xs!n".
  1920 
  1921 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1922 
  1923 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1924   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1925 
  1926 * HOL/record: extensible records with schematic structural subtyping
  1927 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1928 still lacks various theorems and concrete record syntax;
  1929 
  1930 
  1931 *** HOLCF ***
  1932 
  1933 * removed "axioms" and "generated by" sections;
  1934 
  1935 * replaced "ops" section by extended "consts" section, which is capable of
  1936   handling the continuous function space "->" directly;
  1937 
  1938 * domain package:
  1939   . proves theorems immediately and stores them in the theory,
  1940   . creates hierachical name space,
  1941   . now uses normal mixfix annotations (instead of cinfix...),
  1942   . minor changes to some names and values (for consistency),
  1943   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1944   . separator between mutual domain defs: changed "," to "and",
  1945   . improved handling of sort constraints;  now they have to
  1946     appear on the left-hand side of the equations only;
  1947 
  1948 * fixed LAM <x,y,zs>.b syntax;
  1949 
  1950 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1951 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1952 
  1953 
  1954 *** FOL and ZF ***
  1955 
  1956 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1957   with `addloop' of the simplifier to faciliate case splitting in premises.
  1958 
  1959 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1960 in HOL, they strip ALL and --> from proved theorems;
  1961 
  1962 
  1963 
  1964 New in Isabelle94-8 (May 1997)
  1965 ------------------------------
  1966 
  1967 *** General Changes ***
  1968 
  1969 * new utilities to build / run / maintain Isabelle etc. (in parts
  1970 still somewhat experimental); old Makefiles etc. still functional;
  1971 
  1972 * new 'Isabelle System Manual';
  1973 
  1974 * INSTALL text, together with ./configure and ./build scripts;
  1975 
  1976 * reimplemented type inference for greater efficiency, better error
  1977 messages and clean internal interface;
  1978 
  1979 * prlim command for dealing with lots of subgoals (an easier way of
  1980 setting goals_limit);
  1981 
  1982 
  1983 *** Syntax ***
  1984 
  1985 * supports alternative (named) syntax tables (parser and pretty
  1986 printer); internal interface is provided by add_modesyntax(_i);
  1987 
  1988 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1989 be used in conjunction with the Isabelle symbol font; uses the
  1990 "symbols" syntax table;
  1991 
  1992 * added token_translation interface (may translate name tokens in
  1993 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1994 the current print_mode); IMPORTANT: user print translation functions
  1995 are responsible for marking newly introduced bounds
  1996 (Syntax.mark_boundT);
  1997 
  1998 * token translations for modes "xterm" and "xterm_color" that display
  1999 names in bold, underline etc. or colors (which requires a color
  2000 version of xterm);
  2001 
  2002 * infixes may now be declared with names independent of their syntax;
  2003 
  2004 * added typed_print_translation (like print_translation, but may
  2005 access type of constant);
  2006 
  2007 
  2008 *** Classical Reasoner ***
  2009 
  2010 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2011 some limitations.  Blast_tac...
  2012   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2013   + ignores elimination rules that don't have the correct format
  2014         (the conclusion MUST be a formula variable)
  2015   + ignores types, which can make HOL proofs fail
  2016   + rules must not require higher-order unification, e.g. apply_type in ZF
  2017     [message "Function Var's argument not a bound variable" relates to this]
  2018   + its proof strategy is more general but can actually be slower
  2019 
  2020 * substitution with equality assumptions no longer permutes other
  2021 assumptions;
  2022 
  2023 * minor changes in semantics of addafter (now called addaltern); renamed
  2024 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2025 (and access functions for it);
  2026 
  2027 * improved combination of classical reasoner and simplifier:
  2028   + functions for handling clasimpsets
  2029   + improvement of addss: now the simplifier is called _after_ the
  2030     safe steps.
  2031   + safe variant of addss called addSss: uses safe simplifications
  2032     _during_ the safe steps. It is more complete as it allows multiple
  2033     instantiations of unknowns (e.g. with slow_tac).
  2034 
  2035 *** Simplifier ***
  2036 
  2037 * added interface for simplification procedures (functions that
  2038 produce *proven* rewrite rules on the fly, depending on current
  2039 redex);
  2040 
  2041 * ordering on terms as parameter (used for ordered rewriting);
  2042 
  2043 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2044 
  2045 * the solver is now split into a safe and an unsafe part.
  2046 This should be invisible for the normal user, except that the
  2047 functions setsolver and addsolver have been renamed to setSolver and
  2048 addSolver; added safe_asm_full_simp_tac;
  2049 
  2050 
  2051 *** HOL ***
  2052 
  2053 * a generic induction tactic `induct_tac' which works for all datatypes and
  2054 also for type `nat';
  2055 
  2056 * a generic case distinction tactic `exhaust_tac' which works for all
  2057 datatypes and also for type `nat';
  2058 
  2059 * each datatype comes with a function `size';
  2060 
  2061 * patterns in case expressions allow tuple patterns as arguments to
  2062 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2063 
  2064 * primrec now also works with type nat;
  2065 
  2066 * recdef: a new declaration form, allows general recursive functions to be
  2067 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2068 
  2069 * the constant for negation has been renamed from "not" to "Not" to
  2070 harmonize with FOL, ZF, LK, etc.;
  2071 
  2072 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2073 infinite lists;
  2074 
  2075 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2076 
  2077 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2078 problems in commutative rings, using axiomatic type classes for + and *;
  2079 
  2080 * more examples in HOL/MiniML and HOL/Auth;
  2081 
  2082 * more default rewrite rules for quantifiers, union/intersection;
  2083 
  2084 * a new constant `arbitrary == @x.False';
  2085 
  2086 * HOLCF/IOA replaces old HOL/IOA;
  2087 
  2088 * HOLCF changes: derived all rules and arities
  2089   + axiomatic type classes instead of classes
  2090   + typedef instead of faking type definitions
  2091   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2092   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2093   + eliminated the types void, one, tr
  2094   + use unit lift and bool lift (with translations) instead of one and tr
  2095   + eliminated blift from Lift3.thy (use Def instead of blift)
  2096   all eliminated rules are derived as theorems --> no visible changes ;
  2097 
  2098 
  2099 *** ZF ***
  2100 
  2101 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2102 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2103 as ZF_cs addSIs [equalityI];
  2104 
  2105 
  2106 
  2107 New in Isabelle94-7 (November 96)
  2108 ---------------------------------
  2109 
  2110 * allowing negative levels (as offsets) in prlev and choplev;
  2111 
  2112 * super-linear speedup for large simplifications;
  2113 
  2114 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2115 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2116 FAIL); can suppress it using the command Delsimps (ex_simps @
  2117 all_simps); De Morgan laws are also now included, by default;
  2118 
  2119 * improved printing of ==>  :  ~:
  2120 
  2121 * new object-logic "Sequents" adds linear logic, while replacing LK
  2122 and Modal (thanks to Sara Kalvala);
  2123 
  2124 * HOL/Auth: correctness proofs for authentication protocols;
  2125 
  2126 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2127 examples on HOL/Auth);
  2128 
  2129 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2130 the rewriter and classical reasoner simultaneously;
  2131 
  2132 * function uresult no longer returns theorems in "standard" format;
  2133 regain previous version by: val uresult = standard o uresult;
  2134 
  2135 
  2136 
  2137 New in Isabelle94-6
  2138 -------------------
  2139 
  2140 * oracles -- these establish an interface between Isabelle and trusted
  2141 external reasoners, which may deliver results as theorems;
  2142 
  2143 * proof objects (in particular record all uses of oracles);
  2144 
  2145 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2146 
  2147 * "constdefs" section in theory files;
  2148 
  2149 * "primrec" section (HOL) no longer requires names;
  2150 
  2151 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2152 
  2153 
  2154 
  2155 New in Isabelle94-5
  2156 -------------------
  2157 
  2158 * reduced space requirements;
  2159 
  2160 * automatic HTML generation from theories;
  2161 
  2162 * theory files no longer require "..." (quotes) around most types;
  2163 
  2164 * new examples, including two proofs of the Church-Rosser theorem;
  2165 
  2166 * non-curried (1994) version of HOL is no longer distributed;
  2167 
  2168 
  2169 
  2170 New in Isabelle94-4
  2171 -------------------
  2172 
  2173 * greatly reduced space requirements;
  2174 
  2175 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2176 
  2177 * searchable theorem database (see the section "Retrieving theorems" on
  2178 page 8 of the Reference Manual);
  2179 
  2180 * new examples, including Grabczewski's monumental case study of the
  2181 Axiom of Choice;
  2182 
  2183 * The previous version of HOL renamed to Old_HOL;
  2184 
  2185 * The new version of HOL (previously called CHOL) uses a curried syntax
  2186 for functions.  Application looks like f a b instead of f(a,b);
  2187 
  2188 * Mutually recursive inductive definitions finally work in HOL;
  2189 
  2190 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2191 translates to the operator "split";
  2192 
  2193 
  2194 
  2195 New in Isabelle94-3
  2196 -------------------
  2197 
  2198 * new infix operator, addss, allowing the classical reasoner to
  2199 perform simplification at each step of its search.  Example:
  2200         fast_tac (cs addss ss)
  2201 
  2202 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2203 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2204 look like (a,b) instead of <a,b>;
  2205 
  2206 * PLEASE NOTE: CHOL will eventually replace HOL!
  2207 
  2208 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2209 It translates to the operator "split".  A new theory of integers is available;
  2210 
  2211 * In ZF, integer numerals now denote two's-complement binary integers.
  2212 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2213 
  2214 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2215 of the Axiom of Choice;
  2216 
  2217 
  2218 
  2219 New in Isabelle94-2
  2220 -------------------
  2221 
  2222 * Significantly faster resolution;
  2223 
  2224 * the different sections in a .thy file can now be mixed and repeated
  2225 freely;
  2226 
  2227 * Database of theorems for FOL, HOL and ZF.  New
  2228 commands including qed, qed_goal and bind_thm store theorems in the database.
  2229 
  2230 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2231 a given theory (thms_of), or find out what theory a theorem was proved in
  2232 (theory_of_thm);
  2233 
  2234 * Bugs fixed in the inductive definition and datatype packages;
  2235 
  2236 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2237 and HOL_dup_cs obsolete;
  2238 
  2239 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2240 have been removed;
  2241 
  2242 * Simpler definition of function space in ZF;
  2243 
  2244 * new results about cardinal and ordinal arithmetic in ZF;
  2245 
  2246 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2247 types;
  2248 
  2249 
  2250 $Id$