NEWS
author wenzelm
Fri Aug 02 11:49:55 2002 +0200 (2002-08-02)
changeset 13443 1c3327c348b3
parent 13425 119ae829ad9b
child 13459 83f41b047a39
permissions -rw-r--r--
typedef: "open" option;
     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 * 'typedef' command has new option "open" to suppress the set
    32 definition;
    33 
    34 * attribute [symmetric] now works for relations as well; it turns
    35 (x,y) : R^-1 into (y,x) : R, and vice versa;
    36 
    37 * arith(_tac) does now know about div k and mod k where k is a numeral
    38 of type nat or int. It can solve simple goals like
    39 
    40   "0 < n ==> n div 2 < (n::nat)"
    41 
    42 but fails if divisibility plays a role like in
    43 
    44   "n div 2 + (n+1) div 2 = (n::nat)"
    45 
    46 * simp's arithmetic capabilities have been enhanced a bit: it now
    47 takes ~= in premises into account (by performing a case split);
    48 
    49 
    50 
    51 New in Isabelle2002 (March 2002)
    52 --------------------------------
    53 
    54 *** Document preparation ***
    55 
    56 * greatly simplified document preparation setup, including more
    57 graceful interpretation of isatool usedir -i/-d/-D options, and more
    58 instructive isatool mkdir; users should basically be able to get
    59 started with "isatool mkdir HOL Test && isatool make"; alternatively,
    60 users may run a separate document processing stage manually like this:
    61 "isatool usedir -D output HOL Test && isatool document Test/output";
    62 
    63 * theory dependency graph may now be incorporated into documents;
    64 isatool usedir -g true will produce session_graph.eps/.pdf for use
    65 with \includegraphics of LaTeX;
    66 
    67 * proper spacing of consecutive markup elements, especially text
    68 blocks after section headings;
    69 
    70 * support bold style (for single symbols only), input syntax is like
    71 this: "\<^bold>\<alpha>" or "\<^bold>A";
    72 
    73 * \<bullet> is now output as bold \cdot by default, which looks much
    74 better in printed text;
    75 
    76 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
    77 note that these symbols are currently unavailable in Proof General /
    78 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
    79 
    80 * isatool latex no longer depends on changed TEXINPUTS, instead
    81 isatool document copies the Isabelle style files to the target
    82 location;
    83 
    84 
    85 *** Isar ***
    86 
    87 * Pure/Provers: improved proof by cases and induction;
    88   - 'case' command admits impromptu naming of parameters (such as
    89     "case (Suc n)");
    90   - 'induct' method divinates rule instantiation from the inductive
    91     claim; no longer requires excessive ?P bindings for proper
    92     instantiation of cases;
    93   - 'induct' method properly enumerates all possibilities of set/type
    94     rules; as a consequence facts may be also passed through *type*
    95     rules without further ado;
    96   - 'induct' method now derives symbolic cases from the *rulified*
    97     rule (before it used to rulify cases stemming from the internal
    98     atomized version); this means that the context of a non-atomic
    99     statement becomes is included in the hypothesis, avoiding the
   100     slightly cumbersome show "PROP ?case" form;
   101   - 'induct' may now use elim-style induction rules without chaining
   102     facts, using ``missing'' premises from the goal state; this allows
   103     rules stemming from inductive sets to be applied in unstructured
   104     scripts, while still benefitting from proper handling of non-atomic
   105     statements; NB: major inductive premises need to be put first, all
   106     the rest of the goal is passed through the induction;
   107   - 'induct' proper support for mutual induction involving non-atomic
   108     rule statements (uses the new concept of simultaneous goals, see
   109     below);
   110   - append all possible rule selections, but only use the first
   111     success (no backtracking);
   112   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   113   - undeclared rule case names default to numbers 1, 2, 3, ...;
   114   - added 'print_induct_rules' (covered by help item in recent Proof
   115     General versions);
   116   - moved induct/cases attributes to Pure, methods to Provers;
   117   - generic method setup instantiated for FOL and HOL;
   118 
   119 * Pure: support multiple simultaneous goal statements, for example
   120 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   121 meta-level mechanism, this acts as if several individual goals had
   122 been stated separately; in particular common proof methods need to be
   123 repeated in order to cover all claims; note that a single elimination
   124 step is *not* sufficient to establish the two conjunctions, so this
   125 fails:
   126 
   127   assume "A & B" then have A and B ..   (*".." fails*)
   128 
   129 better use "obtain" in situations as above; alternative refer to
   130 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   131 
   132 * Pure: proper integration with ``locales''; unlike the original
   133 version by Florian Kammüller, Isar locales package high-level proof
   134 contexts rather than raw logical ones (e.g. we admit to include
   135 attributes everywhere); operations on locales include merge and
   136 rename; support for implicit arguments (``structures''); simultaneous
   137 type-inference over imports and text; see also HOL/ex/Locales.thy for
   138 some examples;
   139 
   140 * Pure: the following commands have been ``localized'', supporting a
   141 target locale specification "(in name)": 'lemma', 'theorem',
   142 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   143 stored both within the locale and at the theory level (exported and
   144 qualified by the locale name);
   145 
   146 * Pure: theory goals may now be specified in ``long'' form, with
   147 ad-hoc contexts consisting of arbitrary locale elements. for example
   148 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   149 definitions may be given, too); the result is a meta-level rule with
   150 the context elements being discharged in the obvious way;
   151 
   152 * Pure: new proof command 'using' allows to augment currently used
   153 facts after a goal statement ('using' is syntactically analogous to
   154 'apply', but acts on the goal's facts only); this allows chained facts
   155 to be separated into parts given before and after a claim, as in
   156 ``from a and b have C using d and e <proof>'';
   157 
   158 * Pure: renamed "antecedent" case to "rule_context";
   159 
   160 * Pure: new 'judgment' command records explicit information about the
   161 object-logic embedding (used by several tools internally); no longer
   162 use hard-wired "Trueprop";
   163 
   164 * Pure: added 'corollary' command;
   165 
   166 * Pure: fixed 'token_translation' command;
   167 
   168 * Pure: removed obsolete 'exported' attribute;
   169 
   170 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   171 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   172 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   173 
   174 * Pure: method 'atomize' presents local goal premises as object-level
   175 statements (atomic meta-level propositions); setup controlled via
   176 rewrite rules declarations of 'atomize' attribute; example
   177 application: 'induct' method with proper rule statements in improper
   178 proof *scripts*;
   179 
   180 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   181 now consider the syntactic context of assumptions, giving a better
   182 chance to get type-inference of the arguments right (this is
   183 especially important for locales);
   184 
   185 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   186 mode;
   187 
   188 * Pure/obtain: the formal conclusion "thesis", being marked as
   189 ``internal'', may no longer be reference directly in the text;
   190 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   191 situations;
   192 
   193 * Pure: generic 'sym' attribute which declares a rule both as pure
   194 'elim?' and for the 'symmetric' operation;
   195 
   196 * Pure: marginal comments ``--'' may now occur just anywhere in the
   197 text; the fixed correlation with particular command syntax has been
   198 discontinued;
   199 
   200 * Pure: new method 'rules' is particularly well-suited for proof
   201 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   202 but often produces more compact proof terms with less detours;
   203 
   204 * Pure/Provers/classical: simplified integration with pure rule
   205 attributes and methods; the classical "intro?/elim?/dest?"
   206 declarations coincide with the pure ones; the "rule" method no longer
   207 includes classically swapped intros; "intro" and "elim" methods no
   208 longer pick rules from the context; also got rid of ML declarations
   209 AddXIs/AddXEs/AddXDs; all of this has some potential for
   210 INCOMPATIBILITY;
   211 
   212 * Provers/classical: attribute 'swapped' produces classical inversions
   213 of introduction rules;
   214 
   215 * Provers/simplifier: 'simplified' attribute may refer to explicit
   216 rules instead of full simplifier context; 'iff' attribute handles
   217 conditional rules;
   218 
   219 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   220 
   221 * HOL: 'recdef' now fails on unfinished automated proofs, use
   222 "(permissive)" option to recover old behavior;
   223 
   224 * HOL: 'inductive' no longer features separate (collective) attributes
   225 for 'intros' (was found too confusing);
   226 
   227 * HOL: properly declared induction rules less_induct and
   228 wf_induct_rule;
   229 
   230 
   231 *** HOL ***
   232 
   233 * HOL: moved over to sane numeral syntax; the new policy is as
   234 follows:
   235 
   236   - 0 and 1 are polymorphic constants, which are defined on any
   237   numeric type (nat, int, real etc.);
   238 
   239   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   240   binary representation internally;
   241 
   242   - type nat has special constructor Suc, and generally prefers Suc 0
   243   over 1::nat and Suc (Suc 0) over 2::nat;
   244 
   245 This change may cause significant problems of INCOMPATIBILITY; here
   246 are some hints on converting existing sources:
   247 
   248   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   249   entities, so expressions involving "-" (unary or binary minus) need
   250   to be spaced properly;
   251 
   252   - existing occurrences of "1" may need to be constraint "1::nat" or
   253   even replaced by Suc 0; similar for old "2";
   254 
   255   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   256 
   257   - remove all special provisions on numerals in proofs;
   258 
   259 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   260 representation (depends on bin_arith_simps in the default context);
   261 
   262 * HOL: symbolic syntax for x^2 (numeral 2);
   263 
   264 * HOL: the class of all HOL types is now called "type" rather than
   265 "term"; INCOMPATIBILITY, need to adapt references to this type class
   266 in axclass/classes, instance/arities, and (usually rare) occurrences
   267 in typings (of consts etc.); internally the class is called
   268 "HOL.type", ML programs should refer to HOLogic.typeS;
   269 
   270 * HOL/record package improvements:
   271   - new derived operations "fields" to build a partial record section,
   272     "extend" to promote a fixed record to a record scheme, and
   273     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   274     declared as simp by default;
   275   - shared operations ("more", "fields", etc.) now need to be always
   276     qualified) --- potential INCOMPATIBILITY;
   277   - removed "make_scheme" operations (use "make" with "extend") --
   278     INCOMPATIBILITY;
   279   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   280   - provides cases/induct rules for use with corresponding Isar
   281     methods (for concrete records, record schemes, concrete more
   282     parts, and schematic more parts -- in that order);
   283   - internal definitions directly based on a light-weight abstract
   284     theory of product types over typedef rather than datatype;
   285 
   286 * HOL: generic code generator for generating executable ML code from
   287 specifications; specific support for HOL constructs such as inductive
   288 datatypes and sets, as well as recursive functions; can be invoked
   289 via 'generate_code' theory section;
   290 
   291 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   292 
   293 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   294 (beware of argument permutation!);
   295 
   296 * HOL: linorder_less_split superseded by linorder_cases;
   297 
   298 * HOL/List: "nodups" renamed to "distinct";
   299 
   300 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   301 to peripheral theory "Hilbert_Choice";
   302 
   303 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   304 in this (rare) case use:
   305 
   306   delSWrapper "split_all_tac"
   307   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   308 
   309 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   310 MAY FAIL;
   311 
   312 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   313 Isabelle's type classes, ^ on functions and relations has too general
   314 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   315 necessary to attach explicit type constraints;
   316 
   317 * HOL/Relation: the prefix name of the infix "O" has been changed from
   318 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   319 renamed accordingly (eg "compI" -> "rel_compI").
   320 
   321 * HOL: syntax translations now work properly with numerals and records
   322 expressions;
   323 
   324 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   325 of "lam" -- INCOMPATIBILITY;
   326 
   327 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   328 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   329 renamed "Product_Type.unit";
   330 
   331 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   332 
   333 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   334 the "cases" method);
   335 
   336 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   337 Florian Kammüller);
   338 
   339 * HOL/IMP: updated and converted to new-style theory format; several
   340 parts turned into readable document, with proper Isar proof texts and
   341 some explanations (by Gerwin Klein);
   342 
   343 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   344 
   345 * HOL-Hyperreal is now a logic image;
   346 
   347 
   348 *** HOLCF ***
   349 
   350 * Isar: consts/constdefs supports mixfix syntax for continuous
   351 operations;
   352 
   353 * Isar: domain package adapted to new-style theory format, e.g. see
   354 HOLCF/ex/Dnat.thy;
   355 
   356 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   357 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   358 lift.induct_tac, always use UU instead of Undef;
   359 
   360 * HOLCF/IMP: updated and converted to new-style theory;
   361 
   362 
   363 *** ZF ***
   364 
   365 * Isar: proper integration of logic-specific tools and packages,
   366 including theory commands '(co)inductive', '(co)datatype',
   367 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   368 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   369 
   370 * theory Main no longer includes AC; for the Axiom of Choice, base
   371 your theory on Main_ZFC;
   372 
   373 * the integer library now covers quotients and remainders, with many
   374 laws relating division to addition, multiplication, etc.;
   375 
   376 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   377 typeless version of the formalism;
   378 
   379 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   380 format;
   381 
   382 * ZF/Induct: new directory for examples of inductive definitions,
   383 including theory Multiset for multiset orderings; converted to
   384 new-style theory format;
   385 
   386 * ZF: many new theorems about lists, ordinals, etc.;
   387 
   388 
   389 *** General ***
   390 
   391 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   392 variable proof controls level of detail: 0 = no proofs (only oracle
   393 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   394 also ref manual for further ML interfaces;
   395 
   396 * Pure/axclass: removed obsolete ML interface
   397 goal_subclass/goal_arity;
   398 
   399 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   400 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   401 separate tokens, so expressions involving minus need to be spaced
   402 properly;
   403 
   404 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   405 rather than "infixl" or "infixr";
   406 
   407 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   408 sort constraint specifications in type inference; e.g. "x::_::foo"
   409 ensures that the type of "x" is of sort "foo" (but not necessarily a
   410 type variable);
   411 
   412 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   413 control output of nested => (types); the default behavior is
   414 "type_brackets";
   415 
   416 * Pure/syntax: builtin parse translation for "_constify" turns valued
   417 tokens into AST constants;
   418 
   419 * Pure/syntax: prefer later declarations of translations and print
   420 translation functions; potential INCOMPATIBILITY: need to reverse
   421 multiple declarations for same syntax element constant;
   422 
   423 * Pure/show_hyps reset by default (in accordance to existing Isar
   424 practice);
   425 
   426 * Provers/classical: renamed addaltern to addafter, addSaltern to
   427 addSafter;
   428 
   429 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   430 as well;
   431 
   432 * system: tested support for MacOS X; should be able to get Isabelle +
   433 Proof General to work in a plain Terminal after installing Poly/ML
   434 (e.g. from the Isabelle distribution area) and GNU bash alone
   435 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   436 support requires further installations, e.g. from
   437 http://fink.sourceforge.net/);
   438 
   439 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   440 
   441 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   442 of 40 MB), cf. ML_OPTIONS;
   443 
   444 * system: Proof General keywords specification is now part of the
   445 Isabelle distribution (see etc/isar-keywords.el);
   446 
   447 * system: support for persistent Proof General sessions (refrain from
   448 outdating all loaded theories on startup); user may create writable
   449 logic images like this: ``isabelle -q HOL Test'';
   450 
   451 * system: smart selection of Isabelle process versus Isabelle
   452 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   453 run both "isabelle" and "Isabelle" even if file names are badly
   454 damaged (executable inspects the case of the first letter of its own
   455 name); added separate "isabelle-process" and "isabelle-interface";
   456 
   457 * system: refrain from any attempt at filtering input streams; no
   458 longer support ``8bit'' encoding of old isabelle font, instead proper
   459 iso-latin characters may now be used; the related isatools
   460 "symbolinput" and "nonascii" have disappeared as well;
   461 
   462 * system: removed old "xterm" interface (the print modes "xterm" and
   463 "xterm_color" are still available for direct use in a suitable
   464 terminal);
   465 
   466 
   467 
   468 New in Isabelle99-2 (February 2001)
   469 -----------------------------------
   470 
   471 *** Overview of INCOMPATIBILITIES ***
   472 
   473 * HOL: please note that theories in the Library and elsewhere often use the
   474 new-style (Isar) format; to refer to their theorems in an ML script you must
   475 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   476 
   477 * HOL: inductive package no longer splits induction rule aggressively,
   478 but only as far as specified by the introductions given; the old
   479 format may be recovered via ML function complete_split_rule or attribute
   480 'split_rule (complete)';
   481 
   482 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   483 gfp_Tarski to gfp_unfold;
   484 
   485 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   486 
   487 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   488 relation); infix "^^" has been renamed "``"; infix "``" has been
   489 renamed "`"; "univalent" has been renamed "single_valued";
   490 
   491 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   492 operation;
   493 
   494 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   495 
   496 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   497 
   498 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   499 consequence, it is no longer monotonic wrt. the local goal context
   500 (which is now passed through the inductive cases);
   501 
   502 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   503 \<gg> to \<ggreater>;
   504 
   505 
   506 *** Document preparation ***
   507 
   508 * \isabellestyle{NAME} selects version of Isabelle output (currently
   509 available: are "it" for near math-mode best-style output, "sl" for
   510 slanted text style, and "tt" for plain type-writer; if no
   511 \isabellestyle command is given, output is according to slanted
   512 type-writer);
   513 
   514 * support sub/super scripts (for single symbols only), input syntax is
   515 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   516 
   517 * some more standard symbols; see Appendix A of the system manual for
   518 the complete list of symbols defined in isabellesym.sty;
   519 
   520 * improved isabelle style files; more abstract symbol implementation
   521 (should now use \isamath{...} and \isatext{...} in custom symbol
   522 definitions);
   523 
   524 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   525 state; Note that presentation of goal states does not conform to
   526 actual human-readable proof documents.  Please do not include goal
   527 states into document output unless you really know what you are doing!
   528 
   529 * proper indentation of antiquoted output with proportional LaTeX
   530 fonts;
   531 
   532 * no_document ML operator temporarily disables LaTeX document
   533 generation;
   534 
   535 * isatool unsymbolize tunes sources for plain ASCII communication;
   536 
   537 
   538 *** Isar ***
   539 
   540 * Pure: Isar now suffers initial goal statements to contain unbound
   541 schematic variables (this does not conform to actual readable proof
   542 documents, due to unpredictable outcome and non-compositional proof
   543 checking); users who know what they are doing may use schematic goals
   544 for Prolog-style synthesis of proven results;
   545 
   546 * Pure: assumption method (an implicit finishing) now handles actual
   547 rules as well;
   548 
   549 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   550 initial goal, declare "that" only as Pure intro (only for single
   551 steps); the "that" rule assumption may now be involved in implicit
   552 finishing, thus ".." becomes a feasible for trivial obtains;
   553 
   554 * Pure: default proof step now includes 'intro_classes'; thus trivial
   555 instance proofs may be performed by "..";
   556 
   557 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   558 statements as well;
   559 
   560 * Pure: more robust selection of calculational rules;
   561 
   562 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   563 rule (as well as the assumption rule);
   564 
   565 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   566 lemmas, using the graph browser tool;
   567 
   568 * Pure: predict failure of "show" in interactive mode;
   569 
   570 * Pure: 'thms_containing' now takes actual terms as arguments;
   571 
   572 * HOL: improved method 'induct' --- now handles non-atomic goals
   573 (potential INCOMPATIBILITY); tuned error handling;
   574 
   575 * HOL: cases and induct rules now provide explicit hints about the
   576 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   577 any remaining facts are inserted into the goal verbatim;
   578 
   579 * HOL: local contexts (aka cases) may now contain term bindings as
   580 well; the 'cases' and 'induct' methods new provide a ?case binding for
   581 the result to be shown in each case;
   582 
   583 * HOL: added 'recdef_tc' command;
   584 
   585 * isatool convert assists in eliminating legacy ML scripts;
   586 
   587 
   588 *** HOL ***
   589 
   590 * HOL/Library: a collection of generic theories to be used together
   591 with main HOL; the theory loader path already includes this directory
   592 by default; the following existing theories have been moved here:
   593 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   594 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   595 
   596 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   597 modelling and verification task performed in Isabelle/HOL +
   598 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   599 
   600 * HOL/Algebra: special summation operator SUM no longer exists, it has
   601 been replaced by setsum; infix 'assoc' now has priority 50 (like
   602 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   603 'domain', this makes the theory consistent with mathematical
   604 literature;
   605 
   606 * HOL basics: added overloaded operations "inverse" and "divide"
   607 (infix "/"), syntax for generic "abs" operation, generic summation
   608 operator \<Sum>;
   609 
   610 * HOL/typedef: simplified package, provide more useful rules (see also
   611 HOL/subset.thy);
   612 
   613 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   614 now expressed as a proper nested rule (old-style tactic scripts may
   615 require atomize_strip_tac to cope with non-atomic premises);
   616 
   617 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   618 to "split_conv" (old name still available for compatibility);
   619 
   620 * HOL: improved concrete syntax for strings (e.g. allows translation
   621 rules with string literals);
   622 
   623 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   624  and Fleuriot's mechanization of analysis, including the transcendental
   625  functions for the reals;
   626 
   627 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   628 
   629 
   630 *** CTT ***
   631 
   632 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   633 "lam" is displayed as TWO lambda-symbols
   634 
   635 * CTT: theory Main now available, containing everything (that is, Bool
   636 and Arith);
   637 
   638 
   639 *** General ***
   640 
   641 * Pure: the Simplifier has been implemented properly as a derived rule
   642 outside of the actual kernel (at last!); the overall performance
   643 penalty in practical applications is about 50%, while reliability of
   644 the Isabelle inference kernel has been greatly improved;
   645 
   646 * print modes "brackets" and "no_brackets" control output of nested =>
   647 (types) and ==> (props); the default behaviour is "brackets";
   648 
   649 * Provers: fast_tac (and friends) now handle actual object-logic rules
   650 as assumptions as well;
   651 
   652 * system: support Poly/ML 4.0;
   653 
   654 * system: isatool install handles KDE version 1 or 2;
   655 
   656 
   657 
   658 New in Isabelle99-1 (October 2000)
   659 ----------------------------------
   660 
   661 *** Overview of INCOMPATIBILITIES ***
   662 
   663 * HOL: simplification of natural numbers is much changed; to partly
   664 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   665 issue the following ML commands:
   666 
   667   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   668   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   669 
   670 * HOL: simplification no longer dives into case-expressions; this is
   671 controlled by "t.weak_case_cong" for each datatype t;
   672 
   673 * HOL: nat_less_induct renamed to less_induct;
   674 
   675 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   676 fixsome to patch .thy and .ML sources automatically;
   677 
   678   select_equality  -> some_equality
   679   select_eq_Ex     -> some_eq_ex
   680   selectI2EX       -> someI2_ex
   681   selectI2         -> someI2
   682   selectI          -> someI
   683   select1_equality -> some1_equality
   684   Eps_sym_eq       -> some_sym_eq_trivial
   685   Eps_eq           -> some_eq_trivial
   686 
   687 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   688 
   689 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   690 instead);
   691 
   692 * HOL: the recursion equations generated by 'recdef' are now called
   693 f.simps instead of f.rules;
   694 
   695 * HOL: qed_spec_mp now also handles bounded ALL as well;
   696 
   697 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   698 sometimes be needed;
   699 
   700 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   701 
   702 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   703 
   704 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   705 product is now "<*>" instead of "Times"; the lexicographic product is
   706 now "<*lex*>" instead of "**";
   707 
   708 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   709 of main HOL, but was unused); better use HOL's datatype package;
   710 
   711 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   712 the old syntax may be recovered as follows:
   713 
   714   syntax (symbols)
   715     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   716       (infixl "\\<oplus>" 100)
   717 
   718 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   719 
   720 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   721 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   722 internally;
   723 
   724 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   725 changed from A/r to A//r;
   726 
   727 * ZF: new treatment of arithmetic (nat & int) may break some old
   728 proofs;
   729 
   730 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   731 rulify -> rule_format, elimify -> elim_format, ...);
   732 
   733 * Isar/Provers: intro/elim/dest attributes changed; renamed
   734 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   735 should have to change intro!! to intro? only); replaced "delrule" by
   736 "rule del";
   737 
   738 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   739 
   740 * Provers: strengthened force_tac by using new first_best_tac;
   741 
   742 * LaTeX document preparation: several changes of isabelle.sty (see
   743 lib/texinputs);
   744 
   745 
   746 *** Document preparation ***
   747 
   748 * formal comments (text blocks etc.) in new-style theories may now
   749 contain antiquotations of thm/prop/term/typ/text to be presented
   750 according to latex print mode; concrete syntax is like this:
   751 @{term[show_types] "f(x) = a + x"};
   752 
   753 * isatool mkdir provides easy setup of Isabelle session directories,
   754 including proper document sources;
   755 
   756 * generated LaTeX sources are now deleted after successful run
   757 (isatool document -c); may retain a copy somewhere else via -D option
   758 of isatool usedir;
   759 
   760 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   761 style files, achieving self-contained LaTeX sources and simplifying
   762 LaTeX debugging;
   763 
   764 * old-style theories now produce (crude) LaTeX output as well;
   765 
   766 * browser info session directories are now self-contained (may be put
   767 on WWW server seperately); improved graphs of nested sessions; removed
   768 graph for 'all sessions';
   769 
   770 * several improvements in isabelle style files; \isabellestyle{it}
   771 produces fake math mode output; \isamarkupheader is now \section by
   772 default; see lib/texinputs/isabelle.sty etc.;
   773 
   774 
   775 *** Isar ***
   776 
   777 * Isar/Pure: local results and corresponding term bindings are now
   778 subject to Hindley-Milner polymorphism (similar to ML); this
   779 accommodates incremental type-inference very nicely;
   780 
   781 * Isar/Pure: new derived language element 'obtain' supports
   782 generalized existence reasoning;
   783 
   784 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   785 support accumulation of results, without applying any rules yet;
   786 useful to collect intermediate results without explicit name
   787 references, and for use with transitivity rules with more than 2
   788 premises;
   789 
   790 * Isar/Pure: scalable support for case-analysis type proofs: new
   791 'case' language element refers to local contexts symbolically, as
   792 produced by certain proof methods; internally, case names are attached
   793 to theorems as "tags";
   794 
   795 * Isar/Pure: theory command 'hide' removes declarations from
   796 class/type/const name spaces;
   797 
   798 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   799 indicate potential overloading;
   800 
   801 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   802 
   803 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   804 "{a,b,c}" instead of {a,b,c};
   805 
   806 * Isar/Pure now provides its own version of intro/elim/dest
   807 attributes; useful for building new logics, but beware of confusion
   808 with the version in Provers/classical;
   809 
   810 * Isar/Pure: the local context of (non-atomic) goals is provided via
   811 case name 'antecedent';
   812 
   813 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   814 to the current context is now done automatically);
   815 
   816 * Isar/Pure: theory command 'method_setup' provides a simple interface
   817 for definining proof methods in ML;
   818 
   819 * Isar/Provers: intro/elim/dest attributes changed; renamed
   820 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   821 most cases, one should have to change intro!! to intro? only);
   822 replaced "delrule" by "rule del";
   823 
   824 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   825 'symmetric' attribute (the latter supercedes [RS sym]);
   826 
   827 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   828 method modifier); 'simp' method: 'only:' modifier removes loopers as
   829 well (including splits);
   830 
   831 * Isar/Provers: Simplifier and Classical methods now support all kind
   832 of modifiers used in the past, including 'cong', 'iff', etc.
   833 
   834 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   835 of Simplifier and Classical reasoner);
   836 
   837 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   838 now support named cases; major packages (inductive, datatype, primrec,
   839 recdef) support case names and properly name parameters;
   840 
   841 * Isar/HOL: new transitivity rules for substitution in inequalities --
   842 monotonicity conditions are extracted to be proven at end of
   843 calculations;
   844 
   845 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   846 method anyway;
   847 
   848 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   849 split_if split_if_asm; datatype package provides theorems foo.splits =
   850 foo.split foo.split_asm for each datatype;
   851 
   852 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   853 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   854 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   855 use "(cases (simplified))" method in proper proof texts);
   856 
   857 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   858 
   859 * Isar: names of theorems etc. may be natural numbers as well;
   860 
   861 * Isar: 'pr' command: optional arguments for goals_limit and
   862 ProofContext.prems_limit; no longer prints theory contexts, but only
   863 proof states;
   864 
   865 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   866 additional print modes to be specified; e.g. "pr(latex)" will print
   867 proof state according to the Isabelle LaTeX style;
   868 
   869 * Isar: improved support for emulating tactic scripts, including proof
   870 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   871 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   872 (for HOL datatypes);
   873 
   874 * Isar: simplified (more robust) goal selection of proof methods: 1st
   875 goal, all goals, or explicit goal specifier (tactic emulation); thus
   876 'proof method scripts' have to be in depth-first order;
   877 
   878 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   879 
   880 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   881 should instead use individual commands for printing items
   882 (print_commands, print_methods etc.);
   883 
   884 * Isar: added 'nothing' --- the empty list of theorems;
   885 
   886 
   887 *** HOL ***
   888 
   889 * HOL/MicroJava: formalization of a fragment of Java, together with a
   890 corresponding virtual machine and a specification of its bytecode
   891 verifier and a lightweight bytecode verifier, including proofs of
   892 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   893 Cornelia Pusch (see also the homepage of project Bali at
   894 http://isabelle.in.tum.de/Bali/);
   895 
   896 * HOL/Algebra: new theory of rings and univariate polynomials, by
   897 Clemens Ballarin;
   898 
   899 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   900 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   901 Rasmussen;
   902 
   903 * HOL/Lattice: fundamental concepts of lattice theory and order
   904 structures, including duals, properties of bounds versus algebraic
   905 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   906 Theorem for complete lattices etc.; may also serve as a demonstration
   907 for abstract algebraic reasoning using axiomatic type classes, and
   908 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   909 
   910 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   911 von Oheimb;
   912 
   913 * HOL/IMPP: extension of IMP with local variables and mutually
   914 recursive procedures, by David von Oheimb;
   915 
   916 * HOL/Lambda: converted into new-style theory and document;
   917 
   918 * HOL/ex/Multiquote: example of multiple nested quotations and
   919 anti-quotations -- basically a generalized version of de-Bruijn
   920 representation; very useful in avoiding lifting of operations;
   921 
   922 * HOL/record: added general record equality rule to simpset; fixed
   923 select-update simplification procedure to handle extended records as
   924 well; admit "r" as field name;
   925 
   926 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   927 other numeric types and also as the identity of groups, rings, etc.;
   928 
   929 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   930 Types nat and int belong to this axclass;
   931 
   932 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   933    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   934    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   935   two terms #m*u and #n*u are replaced by #(m+n)*u
   936     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   937   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   938     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   939 
   940 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   941 powerful prover for predicate logic but knows nothing of clasets; see
   942 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   943 
   944 * HOL: new version of "case_tac" subsumes both boolean case split and
   945 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   946 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   947 
   948 * HOL: simplification no longer dives into case-expressions: only the
   949 selector expression is simplified, but not the remaining arms; to
   950 enable full simplification of case-expressions for datatype t, you may
   951 remove t.weak_case_cong from the simpset, either globally (Delcongs
   952 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   953 
   954 * HOL/recdef: the recursion equations generated by 'recdef' for
   955 function 'f' are now called f.simps instead of f.rules; if all
   956 termination conditions are proved automatically, these simplification
   957 rules are added to the simpset, as in primrec; rules may be named
   958 individually as well, resulting in a separate list of theorems for
   959 each equation;
   960 
   961 * HOL/While is a new theory that provides a while-combinator. It
   962 permits the definition of tail-recursive functions without the
   963 provision of a termination measure. The latter is necessary once the
   964 invariant proof rule for while is applied.
   965 
   966 * HOL: new (overloaded) notation for the set of elements below/above
   967 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   968 
   969 * HOL: theorems impI, allI, ballI bound as "strip";
   970 
   971 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   972 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   973 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   974 
   975 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   976 
   977 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   978 main HOL, but was unused);
   979 
   980 * HOL: fewer consts declared as global (e.g. have to refer to
   981 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   982 
   983 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   984 in case of overlap with user translations (e.g. judgements over
   985 tuples); (note that the underlying logical represenation is still
   986 bogus);
   987 
   988 
   989 *** ZF ***
   990 
   991 * ZF: simplification automatically cancels common terms in arithmetic
   992 expressions over nat and int;
   993 
   994 * ZF: new treatment of nat to minimize type-checking: all operators
   995 coerce their operands to a natural number using the function natify,
   996 making the algebraic laws unconditional;
   997 
   998 * ZF: as above, for int: operators coerce their operands to an integer
   999 using the function intify;
  1000 
  1001 * ZF: the integer library now contains many of the usual laws for the
  1002 orderings, including $<=, and monotonicity laws for $+ and $*;
  1003 
  1004 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1005 simplification;
  1006 
  1007 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1008 to the simplifier and classical reasoner simultaneously;
  1009 
  1010 
  1011 *** General ***
  1012 
  1013 * Provers: blast_tac now handles actual object-logic rules as
  1014 assumptions; note that auto_tac uses blast_tac internally as well;
  1015 
  1016 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1017 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1018 
  1019 * Provers: delrules now handles destruct rules as well (no longer need
  1020 explicit make_elim);
  1021 
  1022 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1023   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1024 use instead the strong form,
  1025   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1026 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1027 from destruct-rules;
  1028 
  1029 * Provers: Simplifier.easy_setup provides a fast path to basic
  1030 Simplifier setup for new object-logics;
  1031 
  1032 * Pure: AST translation rules no longer require constant head on LHS;
  1033 
  1034 * Pure: improved name spaces: ambiguous output is qualified; support
  1035 for hiding of names;
  1036 
  1037 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1038 XSYMBOL_HOME; no longer need to do manual configuration in most
  1039 situations;
  1040 
  1041 * system: compression of ML heaps images may now be controlled via -c
  1042 option of isabelle and isatool usedir (currently only observed by
  1043 Poly/ML);
  1044 
  1045 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1046 useful for remote X11);
  1047 
  1048 * system: provide TAGS file for Isabelle sources;
  1049 
  1050 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1051 order;
  1052 
  1053 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1054 timing flag supersedes proof_timing and Toplevel.trace;
  1055 
  1056 * ML: new combinators |>> and |>>> for incremental transformations
  1057 with secondary results (e.g. certain theory extensions):
  1058 
  1059 * ML: PureThy.add_defs gets additional argument to indicate potential
  1060 overloading (usually false);
  1061 
  1062 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1063 results;
  1064 
  1065 
  1066 
  1067 New in Isabelle99 (October 1999)
  1068 --------------------------------
  1069 
  1070 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1071 
  1072 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1073 are no longer simplified.  (This allows the simplifier to unfold recursive
  1074 functional programs.)  To restore the old behaviour, declare
  1075 
  1076     Delcongs [if_weak_cong];
  1077 
  1078 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1079 complement;
  1080 
  1081 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1082 
  1083 * HOL/datatype: mutual_induct_tac no longer exists --
  1084   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1085 
  1086 * HOL/typedef: fixed type inference for representing set; type
  1087 arguments now have to occur explicitly on the rhs as type constraints;
  1088 
  1089 * ZF: The con_defs part of an inductive definition may no longer refer
  1090 to constants declared in the same theory;
  1091 
  1092 * HOL, ZF: the function mk_cases, generated by the inductive
  1093 definition package, has lost an argument.  To simplify its result, it
  1094 uses the default simpset instead of a supplied list of theorems.
  1095 
  1096 * HOL/List: the constructors of type list are now Nil and Cons;
  1097 
  1098 * Simplifier: the type of the infix ML functions
  1099         setSSolver addSSolver setSolver addSolver
  1100 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1101 for packaging solvers. A solver is created via
  1102         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1103 where the string argument is only a comment.
  1104 
  1105 
  1106 *** Proof tools ***
  1107 
  1108 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1109 decision procedure for linear arithmetic. Currently it is used for
  1110 types `nat', `int', and `real' in HOL (see below); it can, should and
  1111 will be instantiated for other types and logics as well.
  1112 
  1113 * The simplifier now accepts rewrite rules with flexible heads, eg
  1114      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1115   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1116   matching.
  1117 
  1118 
  1119 *** General ***
  1120 
  1121 * New Isabelle/Isar subsystem provides an alternative to traditional
  1122 tactical theorem proving; together with the ProofGeneral/isar user
  1123 interface it offers an interactive environment for developing human
  1124 readable proof documents (Isar == Intelligible semi-automated
  1125 reasoning); for further information see isatool doc isar-ref,
  1126 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1127 
  1128 * improved and simplified presentation of theories: better HTML markup
  1129 (including colors), graph views in several sizes; isatool usedir now
  1130 provides a proper interface for user theories (via -P option); actual
  1131 document preparation based on (PDF)LaTeX is available as well (for
  1132 new-style theories only); see isatool doc system for more information;
  1133 
  1134 * native support for Proof General, both for classic Isabelle and
  1135 Isabelle/Isar;
  1136 
  1137 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1138 using the graph browser tool;
  1139 
  1140 * Isabelle manuals now also available as PDF;
  1141 
  1142 * theory loader rewritten from scratch (may not be fully
  1143 bug-compatible); old loadpath variable has been replaced by show_path,
  1144 add_path, del_path, reset_path functions; new operations such as
  1145 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1146 isatool doc ref);
  1147 
  1148 * improved isatool install: option -k creates KDE application icon,
  1149 option -p DIR installs standalone binaries;
  1150 
  1151 * added ML_PLATFORM setting (useful for cross-platform installations);
  1152 more robust handling of platform specific ML images for SML/NJ;
  1153 
  1154 * the settings environment is now statically scoped, i.e. it is never
  1155 created again in sub-processes invoked from isabelle, isatool, or
  1156 Isabelle;
  1157 
  1158 * path element specification '~~' refers to '$ISABELLE_HOME';
  1159 
  1160 * in locales, the "assumes" and "defines" parts may be omitted if
  1161 empty;
  1162 
  1163 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1164 long arrows);
  1165 
  1166 * new print_mode "HTML";
  1167 
  1168 * new flag show_tags controls display of tags of theorems (which are
  1169 basically just comments that may be attached by some tools);
  1170 
  1171 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1172 mode and goal output format:
  1173 
  1174 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1175 244c244
  1176 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1177 ---
  1178 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1179 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1180 181c181
  1181 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1182 ---
  1183 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1184 
  1185 * function bind_thms stores lists of theorems (cf. bind_thm);
  1186 
  1187 * new shorthand tactics ftac, eatac, datac, fatac;
  1188 
  1189 * qed (and friends) now accept "" as result name; in that case the
  1190 theorem is not stored, but proper checks and presentation of the
  1191 result still apply;
  1192 
  1193 * theorem database now also indexes constants "Trueprop", "all",
  1194 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1195 
  1196 
  1197 *** HOL ***
  1198 
  1199 ** HOL arithmetic **
  1200 
  1201 * There are now decision procedures for linear arithmetic over nat and
  1202 int:
  1203 
  1204 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1205 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1206 are treated as atomic; subformulae not involving type `nat' or `int'
  1207 are ignored; quantified subformulae are ignored unless they are
  1208 positive universal or negative existential. The tactic has to be
  1209 invoked by hand and can be a little bit slow. In particular, the
  1210 running time is exponential in the number of occurrences of `min' and
  1211 `max', and `-' on `nat'.
  1212 
  1213 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1214 (negated) (in)equalities among the premises and the conclusion into
  1215 account (i.e. no compound formulae) and does not know about `min' and
  1216 `max', and `-' on `nat'. It is fast and is used automatically by the
  1217 simplifier.
  1218 
  1219 NB: At the moment, these decision procedures do not cope with mixed
  1220 nat/int formulae where the two parts interact, such as `m < n ==>
  1221 int(m) < int(n)'.
  1222 
  1223 * HOL/Numeral provides a generic theory of numerals (encoded
  1224 efficiently as bit strings); setup for types nat/int/real is in place;
  1225 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1226 int, existing theories and proof scripts may require a few additional
  1227 type constraints;
  1228 
  1229 * integer division and remainder can now be performed on constant
  1230 arguments;
  1231 
  1232 * many properties of integer multiplication, division and remainder
  1233 are now available;
  1234 
  1235 * An interface to the Stanford Validity Checker (SVC) is available through the
  1236 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1237 are proved automatically.  SVC must be installed separately, and its results
  1238 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1239 invocation of the underlying oracle).  For SVC see
  1240   http://verify.stanford.edu/SVC
  1241 
  1242 * IsaMakefile: the HOL-Real target now builds an actual image;
  1243 
  1244 
  1245 ** HOL misc **
  1246 
  1247 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1248 (in Isabelle/Isar) -- by Gertrud Bauer;
  1249 
  1250 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1251 analysis for assembly languages with subtypes;
  1252 
  1253 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1254 -- avoids syntactic ambiguities and treats state, transition, and
  1255 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1256 changed syntax and (many) tactics;
  1257 
  1258 * HOL/inductive: Now also handles more general introduction rules such
  1259   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1260   theorems are now maintained within the theory (maintained via the
  1261   "mono" attribute);
  1262 
  1263 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1264   (using function types) such as
  1265 
  1266   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1267 
  1268 * HOL/record: record_simproc (part of the default simpset) takes care
  1269 of selectors applied to updated records; record_split_tac is no longer
  1270 part of the default claset; update_defs may now be removed from the
  1271 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1272 
  1273   claset_ref () := claset() addSWrapper record_split_wrapper;
  1274   Delsimprocs [record_simproc]
  1275 
  1276 * HOL/typedef: fixed type inference for representing set; type
  1277 arguments now have to occur explicitly on the rhs as type constraints;
  1278 
  1279 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1280 names rather than an ML expression;
  1281 
  1282 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1283 supplied later.  Program schemes can be defined, such as
  1284     "While B C s = (if B s then While B C (C s) else s)"
  1285 where the well-founded relation can be chosen after B and C have been given.
  1286 
  1287 * HOL/List: the constructors of type list are now Nil and Cons;
  1288 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1289 course, ML tools referring to List.list.op # etc. have to be adapted;
  1290 
  1291 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1292 disabled by default; run isabelle with option -m HOL to get back to
  1293 the original Gordon/HOL-style output;
  1294 
  1295 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1296 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1297 
  1298 * HOL basic syntax simplified (more orthogonal): all variants of
  1299 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1300 Eps operator is provided as well: "SOME x. P[x]";
  1301 
  1302 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1303 
  1304 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1305 thus available for user theories;
  1306 
  1307 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1308 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1309 time;
  1310 
  1311 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1312 several times and then mp;
  1313 
  1314 
  1315 *** LK ***
  1316 
  1317 * the notation <<...>> is now available as a notation for sequences of
  1318 formulas;
  1319 
  1320 * the simplifier is now installed
  1321 
  1322 * the axiom system has been generalized (thanks to Soren Heilmann)
  1323 
  1324 * the classical reasoner now has a default rule database
  1325 
  1326 
  1327 *** ZF ***
  1328 
  1329 * new primrec section allows primitive recursive functions to be given
  1330 directly (as in HOL) over datatypes and the natural numbers;
  1331 
  1332 * new tactics induct_tac and exhaust_tac for induction (or case
  1333 analysis) over datatypes and the natural numbers;
  1334 
  1335 * the datatype declaration of type T now defines the recursor T_rec;
  1336 
  1337 * simplification automatically does freeness reasoning for datatype
  1338 constructors;
  1339 
  1340 * automatic type-inference, with AddTCs command to insert new
  1341 type-checking rules;
  1342 
  1343 * datatype introduction rules are now added as Safe Introduction rules
  1344 to the claset;
  1345 
  1346 * the syntax "if P then x else y" is now available in addition to
  1347 if(P,x,y);
  1348 
  1349 
  1350 *** Internal programming interfaces ***
  1351 
  1352 * tuned simplifier trace output; new flag debug_simp;
  1353 
  1354 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1355 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1356 
  1357 * AxClass.axclass_tac lost the theory argument;
  1358 
  1359 * tuned current_goals_markers semantics: begin / end goal avoids
  1360 printing empty lines;
  1361 
  1362 * removed prs and prs_fn hook, which was broken because it did not
  1363 include \n in its semantics, forcing writeln to add one
  1364 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1365 string -> unit if you really want to output text without newline;
  1366 
  1367 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1368 plain output, interface builders may have to enable 'isabelle_font'
  1369 mode to get Isabelle font glyphs as before;
  1370 
  1371 * refined token_translation interface; INCOMPATIBILITY: output length
  1372 now of type real instead of int;
  1373 
  1374 * theory loader actions may be traced via new ThyInfo.add_hook
  1375 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1376 your own database of information attached to *whole* theories -- as
  1377 opposed to intra-theory data slots offered via TheoryDataFun;
  1378 
  1379 * proper handling of dangling sort hypotheses (at last!);
  1380 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1381 extra sort hypotheses that can be witnessed from the type signature;
  1382 the force_strip_shyps flag is gone, any remaining shyps are simply
  1383 left in the theorem (with a warning issued by strip_shyps_warning);
  1384 
  1385 
  1386 
  1387 New in Isabelle98-1 (October 1998)
  1388 ----------------------------------
  1389 
  1390 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1391 
  1392 * several changes of automated proof tools;
  1393 
  1394 * HOL: major changes to the inductive and datatype packages, including
  1395 some minor incompatibilities of theory syntax;
  1396 
  1397 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1398 called `inj_on';
  1399 
  1400 * HOL: removed duplicate thms in Arith:
  1401   less_imp_add_less  should be replaced by  trans_less_add1
  1402   le_imp_add_le      should be replaced by  trans_le_add1
  1403 
  1404 * HOL: unary minus is now overloaded (new type constraints may be
  1405 required);
  1406 
  1407 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1408 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1409 now taken as an integer constant.
  1410 
  1411 * Pure: ML function 'theory_of' renamed to 'theory';
  1412 
  1413 
  1414 *** Proof tools ***
  1415 
  1416 * Simplifier:
  1417   1. Asm_full_simp_tac is now more aggressive.
  1418      1. It will sometimes reorient premises if that increases their power to
  1419         simplify.
  1420      2. It does no longer proceed strictly from left to right but may also
  1421         rotate premises to achieve further simplification.
  1422      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1423      old Asm_full_simp_tac in that it does not rotate premises.
  1424   2. The simplifier now knows a little bit about nat-arithmetic.
  1425 
  1426 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1427 allows for selected deletion of wrappers, by introduction of names for
  1428 wrapper functionals.  This implies that addbefore, addSbefore,
  1429 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1430 and that adding two tactics with the same name overwrites the first
  1431 one (emitting a warning).
  1432   type wrapper = (int -> tactic) -> (int -> tactic)
  1433   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1434   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1435   delWrapper, delSWrapper: claset *  string            -> claset
  1436   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1437 
  1438 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1439 semantics; addbefore now affects only the unsafe part of step_tac
  1440 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1441 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1442 by Force_tac;
  1443 
  1444 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1445 compWrapper; added safe wrapper (and access functions for it);
  1446 
  1447 * HOL/split_all_tac is now much faster and fails if there is nothing
  1448 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1449 and the names of the automatically generated variables have changed.
  1450 split_all_tac has moved within claset() from unsafe wrappers to safe
  1451 wrappers, which means that !!-bound variables are split much more
  1452 aggressively, and safe_tac and clarify_tac now split such variables.
  1453 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1454 Note: the same holds for record_split_tac, which does the job of
  1455 split_all_tac for record fields.
  1456 
  1457 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1458 permanently to the default simpset using Addsplits just like
  1459 Addsimps. They can be removed via Delsplits just like
  1460 Delsimps. Lower-case versions are also available.
  1461 
  1462 * HOL/Simplifier: The rule split_if is now part of the default
  1463 simpset. This means that the simplifier will eliminate all occurrences
  1464 of if-then-else in the conclusion of a goal. To prevent this, you can
  1465 either remove split_if completely from the default simpset by
  1466 `Delsplits [split_if]' or remove it in a specific call of the
  1467 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1468 other case splitting rules to/from the default simpset: every datatype
  1469 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1470 t is the name of the datatype).
  1471 
  1472 * Classical reasoner / Simplifier combination: new force_tac (and
  1473 derivatives Force_tac, force) combines rewriting and classical
  1474 reasoning (and whatever other tools) similarly to auto_tac, but is
  1475 aimed to solve the given subgoal completely.
  1476 
  1477 
  1478 *** General ***
  1479 
  1480 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1481 and `goalw': the theory is no longer needed as an explicit argument -
  1482 the current theory context is used; assumptions are no longer returned
  1483 at the ML-level unless one of them starts with ==> or !!; it is
  1484 recommended to convert to these new commands using isatool fixgoal
  1485 (backup your sources first!);
  1486 
  1487 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1488 the current theory context, and 'theory' to lookup stored theories;
  1489 
  1490 * new theory section 'locale' for declaring constants, assumptions and
  1491 definitions that have local scope;
  1492 
  1493 * new theory section 'nonterminals' for purely syntactic types;
  1494 
  1495 * new theory section 'setup' for generic ML setup functions
  1496 (e.g. package initialization);
  1497 
  1498 * the distribution now includes Isabelle icons: see
  1499 lib/logo/isabelle-{small,tiny}.xpm;
  1500 
  1501 * isatool install - install binaries with absolute references to
  1502 ISABELLE_HOME/bin;
  1503 
  1504 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1505 
  1506 * print mode 'emacs' reserved for Isamode;
  1507 
  1508 * support multiple print (ast) translations per constant name;
  1509 
  1510 * theorems involving oracles are now printed with a suffixed [!];
  1511 
  1512 
  1513 *** HOL ***
  1514 
  1515 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1516 
  1517 * HOL/inductive package reorganized and improved: now supports mutual
  1518 definitions such as
  1519 
  1520   inductive EVEN ODD
  1521     intrs
  1522       null "0 : EVEN"
  1523       oddI "n : EVEN ==> Suc n : ODD"
  1524       evenI "n : ODD ==> Suc n : EVEN"
  1525 
  1526 new theorem list "elims" contains an elimination rule for each of the
  1527 recursive sets; inductive definitions now handle disjunctive premises
  1528 correctly (also ZF);
  1529 
  1530 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1531 "mutual_induct" no longer exists - the induction rule is always
  1532 contained in "induct";
  1533 
  1534 
  1535 * HOL/datatype package re-implemented and greatly improved: now
  1536 supports mutually recursive datatypes such as
  1537 
  1538   datatype
  1539     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1540             | SUM ('a aexp) ('a aexp)
  1541             | DIFF ('a aexp) ('a aexp)
  1542             | NUM 'a
  1543   and
  1544     'a bexp = LESS ('a aexp) ('a aexp)
  1545             | AND ('a bexp) ('a bexp)
  1546             | OR ('a bexp) ('a bexp)
  1547 
  1548 as well as indirectly recursive datatypes such as
  1549 
  1550   datatype
  1551     ('a, 'b) term = Var 'a
  1552                   | App 'b ((('a, 'b) term) list)
  1553 
  1554 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1555 induction on mutually / indirectly recursive datatypes.
  1556 
  1557 Primrec equations are now stored in theory and can be accessed via
  1558 <function_name>.simps.
  1559 
  1560 INCOMPATIBILITIES:
  1561 
  1562   - Theories using datatypes must now have theory Datatype as an
  1563     ancestor.
  1564   - The specific <typename>.induct_tac no longer exists - use the
  1565     generic induct_tac instead.
  1566   - natE has been renamed to nat.exhaust - use exhaust_tac
  1567     instead of res_inst_tac ... natE. Note that the variable
  1568     names in nat.exhaust differ from the names in natE, this
  1569     may cause some "fragile" proofs to fail.
  1570   - The theorems split_<typename>_case and split_<typename>_case_asm
  1571     have been renamed to <typename>.split and <typename>.split_asm.
  1572   - Since default sorts of type variables are now handled correctly,
  1573     some datatype definitions may have to be annotated with explicit
  1574     sort constraints.
  1575   - Primrec definitions no longer require function name and type
  1576     of recursive argument.
  1577 
  1578 Consider using isatool fixdatatype to adapt your theories and proof
  1579 scripts to the new package (backup your sources first!).
  1580 
  1581 
  1582 * HOL/record package: considerably improved implementation; now
  1583 includes concrete syntax for record types, terms, updates; theorems
  1584 for surjective pairing and splitting !!-bound record variables; proof
  1585 support is as follows:
  1586 
  1587   1) standard conversions (selectors or updates applied to record
  1588 constructor terms) are part of the standard simpset;
  1589 
  1590   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1591 made part of standard simpset and claset via addIffs;
  1592 
  1593   3) a tactic for record field splitting (record_split_tac) is part of
  1594 the standard claset (addSWrapper);
  1595 
  1596 To get a better idea about these rules you may retrieve them via
  1597 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1598 the name of your record type.
  1599 
  1600 The split tactic 3) conceptually simplifies by the following rule:
  1601 
  1602   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1603 
  1604 Thus any record variable that is bound by meta-all will automatically
  1605 blow up into some record constructor term, consequently the
  1606 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1607 solve record problems automatically.
  1608 
  1609 
  1610 * reorganized the main HOL image: HOL/Integ and String loaded by
  1611 default; theory Main includes everything;
  1612 
  1613 * automatic simplification of integer sums and comparisons, using cancellation;
  1614 
  1615 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1616 
  1617 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1618 
  1619 * many new identities for unions, intersections, set difference, etc.;
  1620 
  1621 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1622 called split_if, split_split, split_sum_case and split_nat_case (to go
  1623 with add/delsplits);
  1624 
  1625 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1626 (?x::unit) = (); this is made part of the default simpset, which COULD
  1627 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1628 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1629 unit_abs_eta_conv is added in order to counter the effect of
  1630 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1631 %u.f();
  1632 
  1633 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1634 makes more sense);
  1635 
  1636 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1637   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1638   disjointness reasoning but breaking a few old proofs.
  1639 
  1640 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1641 to 'converse' from 'inverse' (for compatibility with ZF and some
  1642 literature);
  1643 
  1644 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1645 the well-founded relation;
  1646 
  1647 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1648     Compl A.  The "Compl" syntax remains available as input syntax for this
  1649     release ONLY.
  1650 
  1651 * HOL/Update: new theory of function updates:
  1652     f(a:=b) == %x. if x=a then b else f x
  1653 may also be iterated as in f(a:=b,c:=d,...);
  1654 
  1655 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1656 
  1657 * HOL/List:
  1658   - new function list_update written xs[i:=v] that updates the i-th
  1659     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1660   - new function `upt' written [i..j(] which generates the list
  1661     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1662     bound write [i..j], which is a shorthand for [i..j+1(].
  1663   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1664 
  1665 * HOL/Arith:
  1666   - removed 'pred' (predecessor) function;
  1667   - generalized some theorems about n-1;
  1668   - many new laws about "div" and "mod";
  1669   - new laws about greatest common divisors (see theory ex/Primes);
  1670 
  1671 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1672 instead of "inverse";
  1673 
  1674 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1675   of the multiset ordering;
  1676 
  1677 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1678   (not included by default);
  1679 
  1680 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1681 
  1682 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1683   programs, i.e. different program variables may have different types.
  1684 
  1685 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1686   [previously, this check worked only if the rewrite rule was unconditional]
  1687   Now rew can involve either definitions or equalities (either == or =).
  1688 
  1689 
  1690 *** ZF ***
  1691 
  1692 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1693   only the theorems proved on ZF.ML;
  1694 
  1695 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1696   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1697   disjointness reasoning but breaking a few old proofs.
  1698 
  1699 * ZF/Update: new theory of function updates
  1700     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1701   may also be iterated as in f(a:=b,c:=d,...);
  1702 
  1703 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1704 
  1705 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1706   [previously, this check worked only if the rewrite rule was unconditional]
  1707   Now rew can involve either definitions or equalities (either == or =).
  1708 
  1709 * case_tac provided for compatibility with HOL
  1710     (like the old excluded_middle_tac, but with subgoals swapped)
  1711 
  1712 
  1713 *** Internal programming interfaces ***
  1714 
  1715 * Pure: several new basic modules made available for general use, see
  1716 also src/Pure/README;
  1717 
  1718 * improved the theory data mechanism to support encapsulation (data
  1719 kind name replaced by private Object.kind, acting as authorization
  1720 key); new type-safe user interface via functor TheoryDataFun; generic
  1721 print_data function becomes basically useless;
  1722 
  1723 * removed global_names compatibility flag -- all theory declarations
  1724 are qualified by default;
  1725 
  1726 * module Pure/Syntax now offers quote / antiquote translation
  1727 functions (useful for Hoare logic etc. with implicit dependencies);
  1728 see HOL/ex/Antiquote for an example use;
  1729 
  1730 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1731 cterm -> thm;
  1732 
  1733 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1734 subgoal;
  1735 
  1736 * Display.print_goals function moved to Locale.print_goals;
  1737 
  1738 * standard print function for goals supports current_goals_markers
  1739 variable for marking begin of proof, end of proof, start of goal; the
  1740 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1741 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1742 for example;
  1743 
  1744 
  1745 
  1746 New in Isabelle98 (January 1998)
  1747 --------------------------------
  1748 
  1749 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1750 
  1751 * changed lexical syntax of terms / types: dots made part of long
  1752 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1753 
  1754 * simpset (and claset) reference variable replaced by functions
  1755 simpset / simpset_ref;
  1756 
  1757 * no longer supports theory aliases (via merge) and non-trivial
  1758 implicit merge of thms' signatures;
  1759 
  1760 * most internal names of constants changed due to qualified names;
  1761 
  1762 * changed Pure/Sequence interface (see Pure/seq.ML);
  1763 
  1764 
  1765 *** General Changes ***
  1766 
  1767 * hierachically structured name spaces (for consts, types, axms, thms
  1768 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1769 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1770 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1771 long_names for fully qualified output names; NOTE: ML programs
  1772 (special tactics, packages etc.) referring to internal names may have
  1773 to be adapted to cope with fully qualified names; in case of severe
  1774 backward campatibility problems try setting 'global_names' at compile
  1775 time to have enrything declared within a flat name space; one may also
  1776 fine tune name declarations in theories via the 'global' and 'local'
  1777 section;
  1778 
  1779 * reimplemented the implicit simpset and claset using the new anytype
  1780 data filed in signatures; references simpset:simpset ref etc. are
  1781 replaced by functions simpset:unit->simpset and
  1782 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1783 to patch your ML files accordingly;
  1784 
  1785 * HTML output now includes theory graph data for display with Java
  1786 applet or isatool browser; data generated automatically via isatool
  1787 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1788 
  1789 * defs may now be conditional; improved rewrite_goals_tac to handle
  1790 conditional equations;
  1791 
  1792 * defs now admits additional type arguments, using TYPE('a) syntax;
  1793 
  1794 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1795 creates a new theory node; implicit merge of thms' signatures is
  1796 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1797 transfer:theory->thm->thm in (rare) cases;
  1798 
  1799 * improved handling of draft signatures / theories; draft thms (and
  1800 ctyps, cterms) are automatically promoted to real ones;
  1801 
  1802 * slightly changed interfaces for oracles: admit many per theory, named
  1803 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1804 
  1805 * print_goals: optional output of const types (set show_consts and
  1806 show_types);
  1807 
  1808 * improved output of warnings (###) and errors (***);
  1809 
  1810 * subgoal_tac displays a warning if the new subgoal has type variables;
  1811 
  1812 * removed old README and Makefiles;
  1813 
  1814 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1815 
  1816 * removed obsolete init_pps and init_database;
  1817 
  1818 * deleted the obsolete tactical STATE, which was declared by
  1819     fun STATE tacfun st = tacfun st st;
  1820 
  1821 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1822 (which abbreviates $HOME);
  1823 
  1824 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1825 use isatool fixseq to adapt your ML programs (this works for fully
  1826 qualified references to the Sequence structure only!);
  1827 
  1828 * use_thy no longer requires writable current directory; it always
  1829 reloads .ML *and* .thy file, if either one is out of date;
  1830 
  1831 
  1832 *** Classical Reasoner ***
  1833 
  1834 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1835 tactics that use classical reasoning to simplify a subgoal without
  1836 splitting it into several subgoals;
  1837 
  1838 * Safe_tac: like safe_tac but uses the default claset;
  1839 
  1840 
  1841 *** Simplifier ***
  1842 
  1843 * added simplification meta rules:
  1844     (asm_)(full_)simplify: simpset -> thm -> thm;
  1845 
  1846 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1847 logics (again);
  1848 
  1849 * added prems argument to simplification procedures;
  1850 
  1851 * HOL, FOL, ZF: added infix function `addsplits':
  1852   instead of `<simpset> setloop (split_tac <thms>)'
  1853   you can simply write `<simpset> addsplits <thms>'
  1854 
  1855 
  1856 *** Syntax ***
  1857 
  1858 * TYPE('a) syntax for type reflection terms;
  1859 
  1860 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1861 
  1862 * pretty printer: changed order of mixfix annotation preference (again!);
  1863 
  1864 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1865 
  1866 
  1867 *** HOL ***
  1868 
  1869 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1870   with `addloop' of the simplifier to faciliate case splitting in premises.
  1871 
  1872 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1873 
  1874 * HOL/Auth: new protocol proofs including some for the Internet
  1875   protocol TLS;
  1876 
  1877 * HOL/Map: new theory of `maps' a la VDM;
  1878 
  1879 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1880 cancelling out common nat summands from =, <, <= (in)equalities, or
  1881 differences; simplification procedures nat_cancel_factor for
  1882 cancelling common factor from =, <, <= (in)equalities over natural
  1883 sums; nat_cancel contains both kinds of procedures, it is installed by
  1884 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1885 
  1886 * HOL/simplifier: terms of the form
  1887   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1888   are rewritten to
  1889   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1890   and those of the form
  1891   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1892   are rewritten to
  1893   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1894 
  1895 * HOL/datatype
  1896   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1897 
  1898   P(t_case f1 ... fn x) =
  1899      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1900         ...
  1901        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1902      )
  1903 
  1904   and a theorem `split_t_case_asm' of the form
  1905 
  1906   P(t_case f1 ... fn x) =
  1907     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1908         ...
  1909        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1910      )
  1911   which can be added to a simpset via `addsplits'. The existing theorems
  1912   expand_list_case and expand_option_case have been renamed to
  1913   split_list_case and split_option_case.
  1914 
  1915 * HOL/Arithmetic:
  1916   - `pred n' is automatically converted to `n-1'.
  1917     Users are strongly encouraged not to use `pred' any longer,
  1918     because it will disappear altogether at some point.
  1919   - Users are strongly encouraged to write "0 < n" rather than
  1920     "n ~= 0". Theorems and proof tools have been modified towards this
  1921     `standard'.
  1922 
  1923 * HOL/Lists:
  1924   the function "set_of_list" has been renamed "set" (and its theorems too);
  1925   the function "nth" now takes its arguments in the reverse order and
  1926   has acquired the infix notation "!" as in "xs!n".
  1927 
  1928 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1929 
  1930 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1931   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1932 
  1933 * HOL/record: extensible records with schematic structural subtyping
  1934 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1935 still lacks various theorems and concrete record syntax;
  1936 
  1937 
  1938 *** HOLCF ***
  1939 
  1940 * removed "axioms" and "generated by" sections;
  1941 
  1942 * replaced "ops" section by extended "consts" section, which is capable of
  1943   handling the continuous function space "->" directly;
  1944 
  1945 * domain package:
  1946   . proves theorems immediately and stores them in the theory,
  1947   . creates hierachical name space,
  1948   . now uses normal mixfix annotations (instead of cinfix...),
  1949   . minor changes to some names and values (for consistency),
  1950   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1951   . separator between mutual domain defs: changed "," to "and",
  1952   . improved handling of sort constraints;  now they have to
  1953     appear on the left-hand side of the equations only;
  1954 
  1955 * fixed LAM <x,y,zs>.b syntax;
  1956 
  1957 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1958 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1959 
  1960 
  1961 *** FOL and ZF ***
  1962 
  1963 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1964   with `addloop' of the simplifier to faciliate case splitting in premises.
  1965 
  1966 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1967 in HOL, they strip ALL and --> from proved theorems;
  1968 
  1969 
  1970 
  1971 New in Isabelle94-8 (May 1997)
  1972 ------------------------------
  1973 
  1974 *** General Changes ***
  1975 
  1976 * new utilities to build / run / maintain Isabelle etc. (in parts
  1977 still somewhat experimental); old Makefiles etc. still functional;
  1978 
  1979 * new 'Isabelle System Manual';
  1980 
  1981 * INSTALL text, together with ./configure and ./build scripts;
  1982 
  1983 * reimplemented type inference for greater efficiency, better error
  1984 messages and clean internal interface;
  1985 
  1986 * prlim command for dealing with lots of subgoals (an easier way of
  1987 setting goals_limit);
  1988 
  1989 
  1990 *** Syntax ***
  1991 
  1992 * supports alternative (named) syntax tables (parser and pretty
  1993 printer); internal interface is provided by add_modesyntax(_i);
  1994 
  1995 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1996 be used in conjunction with the Isabelle symbol font; uses the
  1997 "symbols" syntax table;
  1998 
  1999 * added token_translation interface (may translate name tokens in
  2000 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2001 the current print_mode); IMPORTANT: user print translation functions
  2002 are responsible for marking newly introduced bounds
  2003 (Syntax.mark_boundT);
  2004 
  2005 * token translations for modes "xterm" and "xterm_color" that display
  2006 names in bold, underline etc. or colors (which requires a color
  2007 version of xterm);
  2008 
  2009 * infixes may now be declared with names independent of their syntax;
  2010 
  2011 * added typed_print_translation (like print_translation, but may
  2012 access type of constant);
  2013 
  2014 
  2015 *** Classical Reasoner ***
  2016 
  2017 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2018 some limitations.  Blast_tac...
  2019   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2020   + ignores elimination rules that don't have the correct format
  2021         (the conclusion MUST be a formula variable)
  2022   + ignores types, which can make HOL proofs fail
  2023   + rules must not require higher-order unification, e.g. apply_type in ZF
  2024     [message "Function Var's argument not a bound variable" relates to this]
  2025   + its proof strategy is more general but can actually be slower
  2026 
  2027 * substitution with equality assumptions no longer permutes other
  2028 assumptions;
  2029 
  2030 * minor changes in semantics of addafter (now called addaltern); renamed
  2031 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2032 (and access functions for it);
  2033 
  2034 * improved combination of classical reasoner and simplifier:
  2035   + functions for handling clasimpsets
  2036   + improvement of addss: now the simplifier is called _after_ the
  2037     safe steps.
  2038   + safe variant of addss called addSss: uses safe simplifications
  2039     _during_ the safe steps. It is more complete as it allows multiple
  2040     instantiations of unknowns (e.g. with slow_tac).
  2041 
  2042 *** Simplifier ***
  2043 
  2044 * added interface for simplification procedures (functions that
  2045 produce *proven* rewrite rules on the fly, depending on current
  2046 redex);
  2047 
  2048 * ordering on terms as parameter (used for ordered rewriting);
  2049 
  2050 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2051 
  2052 * the solver is now split into a safe and an unsafe part.
  2053 This should be invisible for the normal user, except that the
  2054 functions setsolver and addsolver have been renamed to setSolver and
  2055 addSolver; added safe_asm_full_simp_tac;
  2056 
  2057 
  2058 *** HOL ***
  2059 
  2060 * a generic induction tactic `induct_tac' which works for all datatypes and
  2061 also for type `nat';
  2062 
  2063 * a generic case distinction tactic `exhaust_tac' which works for all
  2064 datatypes and also for type `nat';
  2065 
  2066 * each datatype comes with a function `size';
  2067 
  2068 * patterns in case expressions allow tuple patterns as arguments to
  2069 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2070 
  2071 * primrec now also works with type nat;
  2072 
  2073 * recdef: a new declaration form, allows general recursive functions to be
  2074 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2075 
  2076 * the constant for negation has been renamed from "not" to "Not" to
  2077 harmonize with FOL, ZF, LK, etc.;
  2078 
  2079 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2080 infinite lists;
  2081 
  2082 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2083 
  2084 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2085 problems in commutative rings, using axiomatic type classes for + and *;
  2086 
  2087 * more examples in HOL/MiniML and HOL/Auth;
  2088 
  2089 * more default rewrite rules for quantifiers, union/intersection;
  2090 
  2091 * a new constant `arbitrary == @x.False';
  2092 
  2093 * HOLCF/IOA replaces old HOL/IOA;
  2094 
  2095 * HOLCF changes: derived all rules and arities
  2096   + axiomatic type classes instead of classes
  2097   + typedef instead of faking type definitions
  2098   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2099   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2100   + eliminated the types void, one, tr
  2101   + use unit lift and bool lift (with translations) instead of one and tr
  2102   + eliminated blift from Lift3.thy (use Def instead of blift)
  2103   all eliminated rules are derived as theorems --> no visible changes ;
  2104 
  2105 
  2106 *** ZF ***
  2107 
  2108 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2109 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2110 as ZF_cs addSIs [equalityI];
  2111 
  2112 
  2113 
  2114 New in Isabelle94-7 (November 96)
  2115 ---------------------------------
  2116 
  2117 * allowing negative levels (as offsets) in prlev and choplev;
  2118 
  2119 * super-linear speedup for large simplifications;
  2120 
  2121 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2122 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2123 FAIL); can suppress it using the command Delsimps (ex_simps @
  2124 all_simps); De Morgan laws are also now included, by default;
  2125 
  2126 * improved printing of ==>  :  ~:
  2127 
  2128 * new object-logic "Sequents" adds linear logic, while replacing LK
  2129 and Modal (thanks to Sara Kalvala);
  2130 
  2131 * HOL/Auth: correctness proofs for authentication protocols;
  2132 
  2133 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2134 examples on HOL/Auth);
  2135 
  2136 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2137 the rewriter and classical reasoner simultaneously;
  2138 
  2139 * function uresult no longer returns theorems in "standard" format;
  2140 regain previous version by: val uresult = standard o uresult;
  2141 
  2142 
  2143 
  2144 New in Isabelle94-6
  2145 -------------------
  2146 
  2147 * oracles -- these establish an interface between Isabelle and trusted
  2148 external reasoners, which may deliver results as theorems;
  2149 
  2150 * proof objects (in particular record all uses of oracles);
  2151 
  2152 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2153 
  2154 * "constdefs" section in theory files;
  2155 
  2156 * "primrec" section (HOL) no longer requires names;
  2157 
  2158 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2159 
  2160 
  2161 
  2162 New in Isabelle94-5
  2163 -------------------
  2164 
  2165 * reduced space requirements;
  2166 
  2167 * automatic HTML generation from theories;
  2168 
  2169 * theory files no longer require "..." (quotes) around most types;
  2170 
  2171 * new examples, including two proofs of the Church-Rosser theorem;
  2172 
  2173 * non-curried (1994) version of HOL is no longer distributed;
  2174 
  2175 
  2176 
  2177 New in Isabelle94-4
  2178 -------------------
  2179 
  2180 * greatly reduced space requirements;
  2181 
  2182 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2183 
  2184 * searchable theorem database (see the section "Retrieving theorems" on
  2185 page 8 of the Reference Manual);
  2186 
  2187 * new examples, including Grabczewski's monumental case study of the
  2188 Axiom of Choice;
  2189 
  2190 * The previous version of HOL renamed to Old_HOL;
  2191 
  2192 * The new version of HOL (previously called CHOL) uses a curried syntax
  2193 for functions.  Application looks like f a b instead of f(a,b);
  2194 
  2195 * Mutually recursive inductive definitions finally work in HOL;
  2196 
  2197 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2198 translates to the operator "split";
  2199 
  2200 
  2201 
  2202 New in Isabelle94-3
  2203 -------------------
  2204 
  2205 * new infix operator, addss, allowing the classical reasoner to
  2206 perform simplification at each step of its search.  Example:
  2207         fast_tac (cs addss ss)
  2208 
  2209 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2210 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2211 look like (a,b) instead of <a,b>;
  2212 
  2213 * PLEASE NOTE: CHOL will eventually replace HOL!
  2214 
  2215 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2216 It translates to the operator "split".  A new theory of integers is available;
  2217 
  2218 * In ZF, integer numerals now denote two's-complement binary integers.
  2219 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2220 
  2221 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2222 of the Axiom of Choice;
  2223 
  2224 
  2225 
  2226 New in Isabelle94-2
  2227 -------------------
  2228 
  2229 * Significantly faster resolution;
  2230 
  2231 * the different sections in a .thy file can now be mixed and repeated
  2232 freely;
  2233 
  2234 * Database of theorems for FOL, HOL and ZF.  New
  2235 commands including qed, qed_goal and bind_thm store theorems in the database.
  2236 
  2237 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2238 a given theory (thms_of), or find out what theory a theorem was proved in
  2239 (theory_of_thm);
  2240 
  2241 * Bugs fixed in the inductive definition and datatype packages;
  2242 
  2243 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2244 and HOL_dup_cs obsolete;
  2245 
  2246 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2247 have been removed;
  2248 
  2249 * Simpler definition of function space in ZF;
  2250 
  2251 * new results about cardinal and ordinal arithmetic in ZF;
  2252 
  2253 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2254 types;
  2255 
  2256 
  2257 $Id$