NEWS
author nipkow
Fri May 31 07:55:17 2002 +0200 (2002-05-31)
changeset 13190 172f65d0c3d1
parent 13188 596776f878f8
child 13280 306ef3aef61b
permissions -rw-r--r--
*** empty log message ***
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 *** HOL ***
     5 
     6 * arith(_tac) does now know about div k and mod k where k is a numeral of
     7   type nat. It can solve simple goals like "0 < n ==> n div 2 < (n::nat)"
     8   but fails if divisibility plays a role like in
     9   "n div 2 + (n+1) div 2 = (n::nat)".
    10 * simp's arithmetic capabilities have been enhanced a bit:
    11   it now takes ~= in premises into account (by performing a case split).
    12 
    13 New in Isabelle2002 (March 2002)
    14 --------------------------------
    15 
    16 *** Document preparation ***
    17 
    18 * greatly simplified document preparation setup, including more
    19 graceful interpretation of isatool usedir -i/-d/-D options, and more
    20 instructive isatool mkdir; users should basically be able to get
    21 started with "isatool mkdir HOL Test && isatool make"; alternatively,
    22 users may run a separate document processing stage manually like this:
    23 "isatool usedir -D output HOL Test && isatool document Test/output";
    24 
    25 * theory dependency graph may now be incorporated into documents;
    26 isatool usedir -g true will produce session_graph.eps/.pdf for use
    27 with \includegraphics of LaTeX;
    28 
    29 * proper spacing of consecutive markup elements, especially text
    30 blocks after section headings;
    31 
    32 * support bold style (for single symbols only), input syntax is like
    33 this: "\<^bold>\<alpha>" or "\<^bold>A";
    34 
    35 * \<bullet> is now output as bold \cdot by default, which looks much
    36 better in printed text;
    37 
    38 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
    39 note that these symbols are currently unavailable in Proof General /
    40 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
    41 
    42 * isatool latex no longer depends on changed TEXINPUTS, instead
    43 isatool document copies the Isabelle style files to the target
    44 location;
    45 
    46 
    47 *** Isar ***
    48 
    49 * Pure/Provers: improved proof by cases and induction;
    50   - 'case' command admits impromptu naming of parameters (such as
    51     "case (Suc n)");
    52   - 'induct' method divinates rule instantiation from the inductive
    53     claim; no longer requires excessive ?P bindings for proper
    54     instantiation of cases;
    55   - 'induct' method properly enumerates all possibilities of set/type
    56     rules; as a consequence facts may be also passed through *type*
    57     rules without further ado;
    58   - 'induct' method now derives symbolic cases from the *rulified*
    59     rule (before it used to rulify cases stemming from the internal
    60     atomized version); this means that the context of a non-atomic
    61     statement becomes is included in the hypothesis, avoiding the
    62     slightly cumbersome show "PROP ?case" form;
    63   - 'induct' may now use elim-style induction rules without chaining
    64     facts, using ``missing'' premises from the goal state; this allows
    65     rules stemming from inductive sets to be applied in unstructured
    66     scripts, while still benefitting from proper handling of non-atomic
    67     statements; NB: major inductive premises need to be put first, all
    68     the rest of the goal is passed through the induction;
    69   - 'induct' proper support for mutual induction involving non-atomic
    70     rule statements (uses the new concept of simultaneous goals, see
    71     below);
    72   - append all possible rule selections, but only use the first
    73     success (no backtracking);
    74   - removed obsolete "(simplified)" and "(stripped)" options of methods;
    75   - undeclared rule case names default to numbers 1, 2, 3, ...;
    76   - added 'print_induct_rules' (covered by help item in recent Proof
    77     General versions);
    78   - moved induct/cases attributes to Pure, methods to Provers;
    79   - generic method setup instantiated for FOL and HOL;
    80 
    81 * Pure: support multiple simultaneous goal statements, for example
    82 "have a: A and b: B" (same for 'theorem' etc.); being a pure
    83 meta-level mechanism, this acts as if several individual goals had
    84 been stated separately; in particular common proof methods need to be
    85 repeated in order to cover all claims; note that a single elimination
    86 step is *not* sufficient to establish the two conjunctions, so this
    87 fails:
    88 
    89   assume "A & B" then have A and B ..   (*".." fails*)
    90 
    91 better use "obtain" in situations as above; alternative refer to
    92 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
    93 
    94 * Pure: proper integration with ``locales''; unlike the original
    95 version by Florian Kammüller, Isar locales package high-level proof
    96 contexts rather than raw logical ones (e.g. we admit to include
    97 attributes everywhere); operations on locales include merge and
    98 rename; support for implicit arguments (``structures''); simultaneous
    99 type-inference over imports and text; see also HOL/ex/Locales.thy for
   100 some examples;
   101 
   102 * Pure: the following commands have been ``localized'', supporting a
   103 target locale specification "(in name)": 'lemma', 'theorem',
   104 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   105 stored both within the locale and at the theory level (exported and
   106 qualified by the locale name);
   107 
   108 * Pure: theory goals may now be specified in ``long'' form, with
   109 ad-hoc contexts consisting of arbitrary locale elements. for example
   110 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   111 definitions may be given, too); the result is a meta-level rule with
   112 the context elements being discharged in the obvious way;
   113 
   114 * Pure: new proof command 'using' allows to augment currently used
   115 facts after a goal statement ('using' is syntactically analogous to
   116 'apply', but acts on the goal's facts only); this allows chained facts
   117 to be separated into parts given before and after a claim, as in
   118 ``from a and b have C using d and e <proof>'';
   119 
   120 * Pure: renamed "antecedent" case to "rule_context";
   121 
   122 * Pure: new 'judgment' command records explicit information about the
   123 object-logic embedding (used by several tools internally); no longer
   124 use hard-wired "Trueprop";
   125 
   126 * Pure: added 'corollary' command;
   127 
   128 * Pure: fixed 'token_translation' command;
   129 
   130 * Pure: removed obsolete 'exported' attribute;
   131 
   132 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   133 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   134 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   135 
   136 * Pure: method 'atomize' presents local goal premises as object-level
   137 statements (atomic meta-level propositions); setup controlled via
   138 rewrite rules declarations of 'atomize' attribute; example
   139 application: 'induct' method with proper rule statements in improper
   140 proof *scripts*;
   141 
   142 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   143 now consider the syntactic context of assumptions, giving a better
   144 chance to get type-inference of the arguments right (this is
   145 especially important for locales);
   146 
   147 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   148 mode;
   149 
   150 * Pure/obtain: the formal conclusion "thesis", being marked as
   151 ``internal'', may no longer be reference directly in the text;
   152 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   153 situations;
   154 
   155 * Pure: generic 'sym' attribute which declares a rule both as pure
   156 'elim?' and for the 'symmetric' operation;
   157 
   158 * Pure: marginal comments ``--'' may now occur just anywhere in the
   159 text; the fixed correlation with particular command syntax has been
   160 discontinued;
   161 
   162 * Pure: new method 'rules' is particularly well-suited for proof
   163 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   164 but often produces more compact proof terms with less detours;
   165 
   166 * Pure/Provers/classical: simplified integration with pure rule
   167 attributes and methods; the classical "intro?/elim?/dest?"
   168 declarations coincide with the pure ones; the "rule" method no longer
   169 includes classically swapped intros; "intro" and "elim" methods no
   170 longer pick rules from the context; also got rid of ML declarations
   171 AddXIs/AddXEs/AddXDs; all of this has some potential for
   172 INCOMPATIBILITY;
   173 
   174 * Provers/classical: attribute 'swapped' produces classical inversions
   175 of introduction rules;
   176 
   177 * Provers/simplifier: 'simplified' attribute may refer to explicit
   178 rules instead of full simplifier context; 'iff' attribute handles
   179 conditional rules;
   180 
   181 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   182 
   183 * HOL: 'recdef' now fails on unfinished automated proofs, use
   184 "(permissive)" option to recover old behavior;
   185 
   186 * HOL: 'inductive' no longer features separate (collective) attributes
   187 for 'intros' (was found too confusing);
   188 
   189 * HOL: properly declared induction rules less_induct and
   190 wf_induct_rule;
   191 
   192 
   193 *** HOL ***
   194 
   195 * HOL: moved over to sane numeral syntax; the new policy is as
   196 follows:
   197 
   198   - 0 and 1 are polymorphic constants, which are defined on any
   199   numeric type (nat, int, real etc.);
   200 
   201   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   202   binary representation internally;
   203 
   204   - type nat has special constructor Suc, and generally prefers Suc 0
   205   over 1::nat and Suc (Suc 0) over 2::nat;
   206 
   207 This change may cause significant problems of INCOMPATIBILITY; here
   208 are some hints on converting existing sources:
   209 
   210   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   211   entities, so expressions involving "-" (unary or binary minus) need
   212   to be spaced properly;
   213 
   214   - existing occurrences of "1" may need to be constraint "1::nat" or
   215   even replaced by Suc 0; similar for old "2";
   216 
   217   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   218 
   219   - remove all special provisions on numerals in proofs;
   220 
   221 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   222 representation (depends on bin_arith_simps in the default context);
   223 
   224 * HOL: symbolic syntax for x^2 (numeral 2);
   225 
   226 * HOL: the class of all HOL types is now called "type" rather than
   227 "term"; INCOMPATIBILITY, need to adapt references to this type class
   228 in axclass/classes, instance/arities, and (usually rare) occurrences
   229 in typings (of consts etc.); internally the class is called
   230 "HOL.type", ML programs should refer to HOLogic.typeS;
   231 
   232 * HOL/record package improvements:
   233   - new derived operations "fields" to build a partial record section,
   234     "extend" to promote a fixed record to a record scheme, and
   235     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   236     declared as simp by default;
   237   - shared operations ("more", "fields", etc.) now need to be always
   238     qualified) --- potential INCOMPATIBILITY;
   239   - removed "make_scheme" operations (use "make" with "extend") --
   240     INCOMPATIBILITY;
   241   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   242   - provides cases/induct rules for use with corresponding Isar
   243     methods (for concrete records, record schemes, concrete more
   244     parts, and schematic more parts -- in that order);
   245   - internal definitions directly based on a light-weight abstract
   246     theory of product types over typedef rather than datatype;
   247 
   248 * HOL: generic code generator for generating executable ML code from
   249 specifications; specific support for HOL constructs such as inductive
   250 datatypes and sets, as well as recursive functions; can be invoked
   251 via 'generate_code' theory section;
   252 
   253 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   254 
   255 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   256 (beware of argument permutation!);
   257 
   258 * HOL: linorder_less_split superseded by linorder_cases;
   259 
   260 * HOL/List: "nodups" renamed to "distinct";
   261 
   262 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   263 to peripheral theory "Hilbert_Choice";
   264 
   265 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   266 in this (rare) case use:
   267 
   268   delSWrapper "split_all_tac"
   269   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   270 
   271 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   272 MAY FAIL;
   273 
   274 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   275 Isabelle's type classes, ^ on functions and relations has too general
   276 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   277 necessary to attach explicit type constraints;
   278 
   279 * HOL/Relation: the prefix name of the infix "O" has been changed from
   280 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   281 renamed accordingly (eg "compI" -> "rel_compI").
   282 
   283 * HOL: syntax translations now work properly with numerals and records
   284 expressions;
   285 
   286 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   287 of "lam" -- INCOMPATIBILITY;
   288 
   289 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   290 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   291 renamed "Product_Type.unit";
   292 
   293 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   294 
   295 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   296 the "cases" method);
   297 
   298 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   299 Florian Kammüller);
   300 
   301 * HOL/IMP: updated and converted to new-style theory format; several
   302 parts turned into readable document, with proper Isar proof texts and
   303 some explanations (by Gerwin Klein);
   304 
   305 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   306 
   307 * HOL-Hyperreal is now a logic image;
   308 
   309 
   310 *** HOLCF ***
   311 
   312 * Isar: consts/constdefs supports mixfix syntax for continuous
   313 operations;
   314 
   315 * Isar: domain package adapted to new-style theory format, e.g. see
   316 HOLCF/ex/Dnat.thy;
   317 
   318 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   319 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   320 lift.induct_tac, always use UU instead of Undef;
   321 
   322 * HOLCF/IMP: updated and converted to new-style theory;
   323 
   324 
   325 *** ZF ***
   326 
   327 * Isar: proper integration of logic-specific tools and packages,
   328 including theory commands '(co)inductive', '(co)datatype',
   329 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   330 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   331 
   332 * theory Main no longer includes AC; for the Axiom of Choice, base
   333 your theory on Main_ZFC;
   334 
   335 * the integer library now covers quotients and remainders, with many
   336 laws relating division to addition, multiplication, etc.;
   337 
   338 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   339 typeless version of the formalism;
   340 
   341 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   342 format;
   343 
   344 * ZF/Induct: new directory for examples of inductive definitions,
   345 including theory Multiset for multiset orderings; converted to
   346 new-style theory format;
   347 
   348 * ZF: many new theorems about lists, ordinals, etc.;
   349 
   350 
   351 *** General ***
   352 
   353 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   354 variable proof controls level of detail: 0 = no proofs (only oracle
   355 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   356 also ref manual for further ML interfaces;
   357 
   358 * Pure/axclass: removed obsolete ML interface
   359 goal_subclass/goal_arity;
   360 
   361 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   362 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   363 separate tokens, so expressions involving minus need to be spaced
   364 properly;
   365 
   366 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   367 rather than "infixl" or "infixr";
   368 
   369 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   370 sort constraint specifications in type inference; e.g. "x::_::foo"
   371 ensures that the type of "x" is of sort "foo" (but not necessarily a
   372 type variable);
   373 
   374 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   375 control output of nested => (types); the default behavior is
   376 "type_brackets";
   377 
   378 * Pure/syntax: builtin parse translation for "_constify" turns valued
   379 tokens into AST constants;
   380 
   381 * Pure/syntax: prefer later declarations of translations and print
   382 translation functions; potential INCOMPATIBILITY: need to reverse
   383 multiple declarations for same syntax element constant;
   384 
   385 * Pure/show_hyps reset by default (in accordance to existing Isar
   386 practice);
   387 
   388 * Provers/classical: renamed addaltern to addafter, addSaltern to
   389 addSafter;
   390 
   391 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   392 as well;
   393 
   394 * system: tested support for MacOS X; should be able to get Isabelle +
   395 Proof General to work in a plain Terminal after installing Poly/ML
   396 (e.g. from the Isabelle distribution area) and GNU bash alone
   397 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   398 support requires further installations, e.g. from
   399 http://fink.sourceforge.net/);
   400 
   401 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   402 
   403 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   404 of 40 MB), cf. ML_OPTIONS;
   405 
   406 * system: Proof General keywords specification is now part of the
   407 Isabelle distribution (see etc/isar-keywords.el);
   408 
   409 * system: support for persistent Proof General sessions (refrain from
   410 outdating all loaded theories on startup); user may create writable
   411 logic images like this: ``isabelle -q HOL Test'';
   412 
   413 * system: smart selection of Isabelle process versus Isabelle
   414 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   415 run both "isabelle" and "Isabelle" even if file names are badly
   416 damaged (executable inspects the case of the first letter of its own
   417 name); added separate "isabelle-process" and "isabelle-interface";
   418 
   419 * system: refrain from any attempt at filtering input streams; no
   420 longer support ``8bit'' encoding of old isabelle font, instead proper
   421 iso-latin characters may now be used; the related isatools
   422 "symbolinput" and "nonascii" have disappeared as well;
   423 
   424 * system: removed old "xterm" interface (the print modes "xterm" and
   425 "xterm_color" are still available for direct use in a suitable
   426 terminal);
   427 
   428 
   429 
   430 New in Isabelle99-2 (February 2001)
   431 -----------------------------------
   432 
   433 *** Overview of INCOMPATIBILITIES ***
   434 
   435 * HOL: please note that theories in the Library and elsewhere often use the
   436 new-style (Isar) format; to refer to their theorems in an ML script you must
   437 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   438 
   439 * HOL: inductive package no longer splits induction rule aggressively,
   440 but only as far as specified by the introductions given; the old
   441 format may be recovered via ML function complete_split_rule or attribute
   442 'split_rule (complete)';
   443 
   444 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   445 gfp_Tarski to gfp_unfold;
   446 
   447 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   448 
   449 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   450 relation); infix "^^" has been renamed "``"; infix "``" has been
   451 renamed "`"; "univalent" has been renamed "single_valued";
   452 
   453 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   454 operation;
   455 
   456 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   457 
   458 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   459 
   460 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   461 consequence, it is no longer monotonic wrt. the local goal context
   462 (which is now passed through the inductive cases);
   463 
   464 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   465 \<gg> to \<ggreater>;
   466 
   467 
   468 *** Document preparation ***
   469 
   470 * \isabellestyle{NAME} selects version of Isabelle output (currently
   471 available: are "it" for near math-mode best-style output, "sl" for
   472 slanted text style, and "tt" for plain type-writer; if no
   473 \isabellestyle command is given, output is according to slanted
   474 type-writer);
   475 
   476 * support sub/super scripts (for single symbols only), input syntax is
   477 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   478 
   479 * some more standard symbols; see Appendix A of the system manual for
   480 the complete list of symbols defined in isabellesym.sty;
   481 
   482 * improved isabelle style files; more abstract symbol implementation
   483 (should now use \isamath{...} and \isatext{...} in custom symbol
   484 definitions);
   485 
   486 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   487 state; Note that presentation of goal states does not conform to
   488 actual human-readable proof documents.  Please do not include goal
   489 states into document output unless you really know what you are doing!
   490 
   491 * proper indentation of antiquoted output with proportional LaTeX
   492 fonts;
   493 
   494 * no_document ML operator temporarily disables LaTeX document
   495 generation;
   496 
   497 * isatool unsymbolize tunes sources for plain ASCII communication;
   498 
   499 
   500 *** Isar ***
   501 
   502 * Pure: Isar now suffers initial goal statements to contain unbound
   503 schematic variables (this does not conform to actual readable proof
   504 documents, due to unpredictable outcome and non-compositional proof
   505 checking); users who know what they are doing may use schematic goals
   506 for Prolog-style synthesis of proven results;
   507 
   508 * Pure: assumption method (an implicit finishing) now handles actual
   509 rules as well;
   510 
   511 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   512 initial goal, declare "that" only as Pure intro (only for single
   513 steps); the "that" rule assumption may now be involved in implicit
   514 finishing, thus ".." becomes a feasible for trivial obtains;
   515 
   516 * Pure: default proof step now includes 'intro_classes'; thus trivial
   517 instance proofs may be performed by "..";
   518 
   519 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   520 statements as well;
   521 
   522 * Pure: more robust selection of calculational rules;
   523 
   524 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   525 rule (as well as the assumption rule);
   526 
   527 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   528 lemmas, using the graph browser tool;
   529 
   530 * Pure: predict failure of "show" in interactive mode;
   531 
   532 * Pure: 'thms_containing' now takes actual terms as arguments;
   533 
   534 * HOL: improved method 'induct' --- now handles non-atomic goals
   535 (potential INCOMPATIBILITY); tuned error handling;
   536 
   537 * HOL: cases and induct rules now provide explicit hints about the
   538 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   539 any remaining facts are inserted into the goal verbatim;
   540 
   541 * HOL: local contexts (aka cases) may now contain term bindings as
   542 well; the 'cases' and 'induct' methods new provide a ?case binding for
   543 the result to be shown in each case;
   544 
   545 * HOL: added 'recdef_tc' command;
   546 
   547 * isatool convert assists in eliminating legacy ML scripts;
   548 
   549 
   550 *** HOL ***
   551 
   552 * HOL/Library: a collection of generic theories to be used together
   553 with main HOL; the theory loader path already includes this directory
   554 by default; the following existing theories have been moved here:
   555 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   556 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   557 
   558 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   559 modelling and verification task performed in Isabelle/HOL +
   560 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   561 
   562 * HOL/Algebra: special summation operator SUM no longer exists, it has
   563 been replaced by setsum; infix 'assoc' now has priority 50 (like
   564 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   565 'domain', this makes the theory consistent with mathematical
   566 literature;
   567 
   568 * HOL basics: added overloaded operations "inverse" and "divide"
   569 (infix "/"), syntax for generic "abs" operation, generic summation
   570 operator \<Sum>;
   571 
   572 * HOL/typedef: simplified package, provide more useful rules (see also
   573 HOL/subset.thy);
   574 
   575 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   576 now expressed as a proper nested rule (old-style tactic scripts may
   577 require atomize_strip_tac to cope with non-atomic premises);
   578 
   579 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   580 to "split_conv" (old name still available for compatibility);
   581 
   582 * HOL: improved concrete syntax for strings (e.g. allows translation
   583 rules with string literals);
   584 
   585 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   586  and Fleuriot's mechanization of analysis, including the transcendental
   587  functions for the reals;
   588 
   589 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   590 
   591 
   592 *** CTT ***
   593 
   594 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   595 "lam" is displayed as TWO lambda-symbols
   596 
   597 * CTT: theory Main now available, containing everything (that is, Bool
   598 and Arith);
   599 
   600 
   601 *** General ***
   602 
   603 * Pure: the Simplifier has been implemented properly as a derived rule
   604 outside of the actual kernel (at last!); the overall performance
   605 penalty in practical applications is about 50%, while reliability of
   606 the Isabelle inference kernel has been greatly improved;
   607 
   608 * print modes "brackets" and "no_brackets" control output of nested =>
   609 (types) and ==> (props); the default behaviour is "brackets";
   610 
   611 * Provers: fast_tac (and friends) now handle actual object-logic rules
   612 as assumptions as well;
   613 
   614 * system: support Poly/ML 4.0;
   615 
   616 * system: isatool install handles KDE version 1 or 2;
   617 
   618 
   619 
   620 New in Isabelle99-1 (October 2000)
   621 ----------------------------------
   622 
   623 *** Overview of INCOMPATIBILITIES ***
   624 
   625 * HOL: simplification of natural numbers is much changed; to partly
   626 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   627 issue the following ML commands:
   628 
   629   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   630   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   631 
   632 * HOL: simplification no longer dives into case-expressions; this is
   633 controlled by "t.weak_case_cong" for each datatype t;
   634 
   635 * HOL: nat_less_induct renamed to less_induct;
   636 
   637 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   638 fixsome to patch .thy and .ML sources automatically;
   639 
   640   select_equality  -> some_equality
   641   select_eq_Ex     -> some_eq_ex
   642   selectI2EX       -> someI2_ex
   643   selectI2         -> someI2
   644   selectI          -> someI
   645   select1_equality -> some1_equality
   646   Eps_sym_eq       -> some_sym_eq_trivial
   647   Eps_eq           -> some_eq_trivial
   648 
   649 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   650 
   651 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   652 instead);
   653 
   654 * HOL: the recursion equations generated by 'recdef' are now called
   655 f.simps instead of f.rules;
   656 
   657 * HOL: qed_spec_mp now also handles bounded ALL as well;
   658 
   659 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   660 sometimes be needed;
   661 
   662 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   663 
   664 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   665 
   666 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   667 product is now "<*>" instead of "Times"; the lexicographic product is
   668 now "<*lex*>" instead of "**";
   669 
   670 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   671 of main HOL, but was unused); better use HOL's datatype package;
   672 
   673 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   674 the old syntax may be recovered as follows:
   675 
   676   syntax (symbols)
   677     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   678       (infixl "\\<oplus>" 100)
   679 
   680 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   681 
   682 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   683 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   684 internally;
   685 
   686 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   687 changed from A/r to A//r;
   688 
   689 * ZF: new treatment of arithmetic (nat & int) may break some old
   690 proofs;
   691 
   692 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   693 rulify -> rule_format, elimify -> elim_format, ...);
   694 
   695 * Isar/Provers: intro/elim/dest attributes changed; renamed
   696 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   697 should have to change intro!! to intro? only); replaced "delrule" by
   698 "rule del";
   699 
   700 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   701 
   702 * Provers: strengthened force_tac by using new first_best_tac;
   703 
   704 * LaTeX document preparation: several changes of isabelle.sty (see
   705 lib/texinputs);
   706 
   707 
   708 *** Document preparation ***
   709 
   710 * formal comments (text blocks etc.) in new-style theories may now
   711 contain antiquotations of thm/prop/term/typ/text to be presented
   712 according to latex print mode; concrete syntax is like this:
   713 @{term[show_types] "f(x) = a + x"};
   714 
   715 * isatool mkdir provides easy setup of Isabelle session directories,
   716 including proper document sources;
   717 
   718 * generated LaTeX sources are now deleted after successful run
   719 (isatool document -c); may retain a copy somewhere else via -D option
   720 of isatool usedir;
   721 
   722 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   723 style files, achieving self-contained LaTeX sources and simplifying
   724 LaTeX debugging;
   725 
   726 * old-style theories now produce (crude) LaTeX output as well;
   727 
   728 * browser info session directories are now self-contained (may be put
   729 on WWW server seperately); improved graphs of nested sessions; removed
   730 graph for 'all sessions';
   731 
   732 * several improvements in isabelle style files; \isabellestyle{it}
   733 produces fake math mode output; \isamarkupheader is now \section by
   734 default; see lib/texinputs/isabelle.sty etc.;
   735 
   736 
   737 *** Isar ***
   738 
   739 * Isar/Pure: local results and corresponding term bindings are now
   740 subject to Hindley-Milner polymorphism (similar to ML); this
   741 accommodates incremental type-inference very nicely;
   742 
   743 * Isar/Pure: new derived language element 'obtain' supports
   744 generalized existence reasoning;
   745 
   746 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   747 support accumulation of results, without applying any rules yet;
   748 useful to collect intermediate results without explicit name
   749 references, and for use with transitivity rules with more than 2
   750 premises;
   751 
   752 * Isar/Pure: scalable support for case-analysis type proofs: new
   753 'case' language element refers to local contexts symbolically, as
   754 produced by certain proof methods; internally, case names are attached
   755 to theorems as "tags";
   756 
   757 * Isar/Pure: theory command 'hide' removes declarations from
   758 class/type/const name spaces;
   759 
   760 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   761 indicate potential overloading;
   762 
   763 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   764 
   765 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   766 "{a,b,c}" instead of {a,b,c};
   767 
   768 * Isar/Pure now provides its own version of intro/elim/dest
   769 attributes; useful for building new logics, but beware of confusion
   770 with the version in Provers/classical;
   771 
   772 * Isar/Pure: the local context of (non-atomic) goals is provided via
   773 case name 'antecedent';
   774 
   775 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   776 to the current context is now done automatically);
   777 
   778 * Isar/Pure: theory command 'method_setup' provides a simple interface
   779 for definining proof methods in ML;
   780 
   781 * Isar/Provers: intro/elim/dest attributes changed; renamed
   782 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   783 most cases, one should have to change intro!! to intro? only);
   784 replaced "delrule" by "rule del";
   785 
   786 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   787 'symmetric' attribute (the latter supercedes [RS sym]);
   788 
   789 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   790 method modifier); 'simp' method: 'only:' modifier removes loopers as
   791 well (including splits);
   792 
   793 * Isar/Provers: Simplifier and Classical methods now support all kind
   794 of modifiers used in the past, including 'cong', 'iff', etc.
   795 
   796 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   797 of Simplifier and Classical reasoner);
   798 
   799 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   800 now support named cases; major packages (inductive, datatype, primrec,
   801 recdef) support case names and properly name parameters;
   802 
   803 * Isar/HOL: new transitivity rules for substitution in inequalities --
   804 monotonicity conditions are extracted to be proven at end of
   805 calculations;
   806 
   807 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   808 method anyway;
   809 
   810 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   811 split_if split_if_asm; datatype package provides theorems foo.splits =
   812 foo.split foo.split_asm for each datatype;
   813 
   814 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   815 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   816 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   817 use "(cases (simplified))" method in proper proof texts);
   818 
   819 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   820 
   821 * Isar: names of theorems etc. may be natural numbers as well;
   822 
   823 * Isar: 'pr' command: optional arguments for goals_limit and
   824 ProofContext.prems_limit; no longer prints theory contexts, but only
   825 proof states;
   826 
   827 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   828 additional print modes to be specified; e.g. "pr(latex)" will print
   829 proof state according to the Isabelle LaTeX style;
   830 
   831 * Isar: improved support for emulating tactic scripts, including proof
   832 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   833 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   834 (for HOL datatypes);
   835 
   836 * Isar: simplified (more robust) goal selection of proof methods: 1st
   837 goal, all goals, or explicit goal specifier (tactic emulation); thus
   838 'proof method scripts' have to be in depth-first order;
   839 
   840 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   841 
   842 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   843 should instead use individual commands for printing items
   844 (print_commands, print_methods etc.);
   845 
   846 * Isar: added 'nothing' --- the empty list of theorems;
   847 
   848 
   849 *** HOL ***
   850 
   851 * HOL/MicroJava: formalization of a fragment of Java, together with a
   852 corresponding virtual machine and a specification of its bytecode
   853 verifier and a lightweight bytecode verifier, including proofs of
   854 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   855 Cornelia Pusch (see also the homepage of project Bali at
   856 http://isabelle.in.tum.de/Bali/);
   857 
   858 * HOL/Algebra: new theory of rings and univariate polynomials, by
   859 Clemens Ballarin;
   860 
   861 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   862 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   863 Rasmussen;
   864 
   865 * HOL/Lattice: fundamental concepts of lattice theory and order
   866 structures, including duals, properties of bounds versus algebraic
   867 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   868 Theorem for complete lattices etc.; may also serve as a demonstration
   869 for abstract algebraic reasoning using axiomatic type classes, and
   870 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   871 
   872 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   873 von Oheimb;
   874 
   875 * HOL/IMPP: extension of IMP with local variables and mutually
   876 recursive procedures, by David von Oheimb;
   877 
   878 * HOL/Lambda: converted into new-style theory and document;
   879 
   880 * HOL/ex/Multiquote: example of multiple nested quotations and
   881 anti-quotations -- basically a generalized version of de-Bruijn
   882 representation; very useful in avoiding lifting of operations;
   883 
   884 * HOL/record: added general record equality rule to simpset; fixed
   885 select-update simplification procedure to handle extended records as
   886 well; admit "r" as field name;
   887 
   888 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   889 other numeric types and also as the identity of groups, rings, etc.;
   890 
   891 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   892 Types nat and int belong to this axclass;
   893 
   894 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   895    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   896    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   897   two terms #m*u and #n*u are replaced by #(m+n)*u
   898     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   899   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   900     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   901 
   902 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   903 powerful prover for predicate logic but knows nothing of clasets; see
   904 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   905 
   906 * HOL: new version of "case_tac" subsumes both boolean case split and
   907 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   908 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   909 
   910 * HOL: simplification no longer dives into case-expressions: only the
   911 selector expression is simplified, but not the remaining arms; to
   912 enable full simplification of case-expressions for datatype t, you may
   913 remove t.weak_case_cong from the simpset, either globally (Delcongs
   914 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   915 
   916 * HOL/recdef: the recursion equations generated by 'recdef' for
   917 function 'f' are now called f.simps instead of f.rules; if all
   918 termination conditions are proved automatically, these simplification
   919 rules are added to the simpset, as in primrec; rules may be named
   920 individually as well, resulting in a separate list of theorems for
   921 each equation;
   922 
   923 * HOL/While is a new theory that provides a while-combinator. It
   924 permits the definition of tail-recursive functions without the
   925 provision of a termination measure. The latter is necessary once the
   926 invariant proof rule for while is applied.
   927 
   928 * HOL: new (overloaded) notation for the set of elements below/above
   929 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   930 
   931 * HOL: theorems impI, allI, ballI bound as "strip";
   932 
   933 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   934 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   935 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   936 
   937 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   938 
   939 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   940 main HOL, but was unused);
   941 
   942 * HOL: fewer consts declared as global (e.g. have to refer to
   943 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   944 
   945 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   946 in case of overlap with user translations (e.g. judgements over
   947 tuples); (note that the underlying logical represenation is still
   948 bogus);
   949 
   950 
   951 *** ZF ***
   952 
   953 * ZF: simplification automatically cancels common terms in arithmetic
   954 expressions over nat and int;
   955 
   956 * ZF: new treatment of nat to minimize type-checking: all operators
   957 coerce their operands to a natural number using the function natify,
   958 making the algebraic laws unconditional;
   959 
   960 * ZF: as above, for int: operators coerce their operands to an integer
   961 using the function intify;
   962 
   963 * ZF: the integer library now contains many of the usual laws for the
   964 orderings, including $<=, and monotonicity laws for $+ and $*;
   965 
   966 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
   967 simplification;
   968 
   969 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
   970 to the simplifier and classical reasoner simultaneously;
   971 
   972 
   973 *** General ***
   974 
   975 * Provers: blast_tac now handles actual object-logic rules as
   976 assumptions; note that auto_tac uses blast_tac internally as well;
   977 
   978 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
   979 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
   980 
   981 * Provers: delrules now handles destruct rules as well (no longer need
   982 explicit make_elim);
   983 
   984 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
   985   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   986 use instead the strong form,
   987   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   988 in HOL, FOL and ZF the function cla_make_elim will create such rules
   989 from destruct-rules;
   990 
   991 * Provers: Simplifier.easy_setup provides a fast path to basic
   992 Simplifier setup for new object-logics;
   993 
   994 * Pure: AST translation rules no longer require constant head on LHS;
   995 
   996 * Pure: improved name spaces: ambiguous output is qualified; support
   997 for hiding of names;
   998 
   999 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1000 XSYMBOL_HOME; no longer need to do manual configuration in most
  1001 situations;
  1002 
  1003 * system: compression of ML heaps images may now be controlled via -c
  1004 option of isabelle and isatool usedir (currently only observed by
  1005 Poly/ML);
  1006 
  1007 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1008 useful for remote X11);
  1009 
  1010 * system: provide TAGS file for Isabelle sources;
  1011 
  1012 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1013 order;
  1014 
  1015 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1016 timing flag supersedes proof_timing and Toplevel.trace;
  1017 
  1018 * ML: new combinators |>> and |>>> for incremental transformations
  1019 with secondary results (e.g. certain theory extensions):
  1020 
  1021 * ML: PureThy.add_defs gets additional argument to indicate potential
  1022 overloading (usually false);
  1023 
  1024 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1025 results;
  1026 
  1027 
  1028 
  1029 New in Isabelle99 (October 1999)
  1030 --------------------------------
  1031 
  1032 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1033 
  1034 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1035 are no longer simplified.  (This allows the simplifier to unfold recursive
  1036 functional programs.)  To restore the old behaviour, declare
  1037 
  1038     Delcongs [if_weak_cong];
  1039 
  1040 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1041 complement;
  1042 
  1043 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1044 
  1045 * HOL/datatype: mutual_induct_tac no longer exists --
  1046   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1047 
  1048 * HOL/typedef: fixed type inference for representing set; type
  1049 arguments now have to occur explicitly on the rhs as type constraints;
  1050 
  1051 * ZF: The con_defs part of an inductive definition may no longer refer
  1052 to constants declared in the same theory;
  1053 
  1054 * HOL, ZF: the function mk_cases, generated by the inductive
  1055 definition package, has lost an argument.  To simplify its result, it
  1056 uses the default simpset instead of a supplied list of theorems.
  1057 
  1058 * HOL/List: the constructors of type list are now Nil and Cons;
  1059 
  1060 * Simplifier: the type of the infix ML functions
  1061         setSSolver addSSolver setSolver addSolver
  1062 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1063 for packaging solvers. A solver is created via
  1064         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1065 where the string argument is only a comment.
  1066 
  1067 
  1068 *** Proof tools ***
  1069 
  1070 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1071 decision procedure for linear arithmetic. Currently it is used for
  1072 types `nat', `int', and `real' in HOL (see below); it can, should and
  1073 will be instantiated for other types and logics as well.
  1074 
  1075 * The simplifier now accepts rewrite rules with flexible heads, eg
  1076      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1077   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1078   matching.
  1079 
  1080 
  1081 *** General ***
  1082 
  1083 * New Isabelle/Isar subsystem provides an alternative to traditional
  1084 tactical theorem proving; together with the ProofGeneral/isar user
  1085 interface it offers an interactive environment for developing human
  1086 readable proof documents (Isar == Intelligible semi-automated
  1087 reasoning); for further information see isatool doc isar-ref,
  1088 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1089 
  1090 * improved and simplified presentation of theories: better HTML markup
  1091 (including colors), graph views in several sizes; isatool usedir now
  1092 provides a proper interface for user theories (via -P option); actual
  1093 document preparation based on (PDF)LaTeX is available as well (for
  1094 new-style theories only); see isatool doc system for more information;
  1095 
  1096 * native support for Proof General, both for classic Isabelle and
  1097 Isabelle/Isar;
  1098 
  1099 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1100 using the graph browser tool;
  1101 
  1102 * Isabelle manuals now also available as PDF;
  1103 
  1104 * theory loader rewritten from scratch (may not be fully
  1105 bug-compatible); old loadpath variable has been replaced by show_path,
  1106 add_path, del_path, reset_path functions; new operations such as
  1107 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1108 isatool doc ref);
  1109 
  1110 * improved isatool install: option -k creates KDE application icon,
  1111 option -p DIR installs standalone binaries;
  1112 
  1113 * added ML_PLATFORM setting (useful for cross-platform installations);
  1114 more robust handling of platform specific ML images for SML/NJ;
  1115 
  1116 * the settings environment is now statically scoped, i.e. it is never
  1117 created again in sub-processes invoked from isabelle, isatool, or
  1118 Isabelle;
  1119 
  1120 * path element specification '~~' refers to '$ISABELLE_HOME';
  1121 
  1122 * in locales, the "assumes" and "defines" parts may be omitted if
  1123 empty;
  1124 
  1125 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1126 long arrows);
  1127 
  1128 * new print_mode "HTML";
  1129 
  1130 * new flag show_tags controls display of tags of theorems (which are
  1131 basically just comments that may be attached by some tools);
  1132 
  1133 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1134 mode and goal output format:
  1135 
  1136 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1137 244c244
  1138 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1139 ---
  1140 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1141 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1142 181c181
  1143 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1144 ---
  1145 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1146 
  1147 * function bind_thms stores lists of theorems (cf. bind_thm);
  1148 
  1149 * new shorthand tactics ftac, eatac, datac, fatac;
  1150 
  1151 * qed (and friends) now accept "" as result name; in that case the
  1152 theorem is not stored, but proper checks and presentation of the
  1153 result still apply;
  1154 
  1155 * theorem database now also indexes constants "Trueprop", "all",
  1156 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1157 
  1158 
  1159 *** HOL ***
  1160 
  1161 ** HOL arithmetic **
  1162 
  1163 * There are now decision procedures for linear arithmetic over nat and
  1164 int:
  1165 
  1166 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1167 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1168 are treated as atomic; subformulae not involving type `nat' or `int'
  1169 are ignored; quantified subformulae are ignored unless they are
  1170 positive universal or negative existential. The tactic has to be
  1171 invoked by hand and can be a little bit slow. In particular, the
  1172 running time is exponential in the number of occurrences of `min' and
  1173 `max', and `-' on `nat'.
  1174 
  1175 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1176 (negated) (in)equalities among the premises and the conclusion into
  1177 account (i.e. no compound formulae) and does not know about `min' and
  1178 `max', and `-' on `nat'. It is fast and is used automatically by the
  1179 simplifier.
  1180 
  1181 NB: At the moment, these decision procedures do not cope with mixed
  1182 nat/int formulae where the two parts interact, such as `m < n ==>
  1183 int(m) < int(n)'.
  1184 
  1185 * HOL/Numeral provides a generic theory of numerals (encoded
  1186 efficiently as bit strings); setup for types nat/int/real is in place;
  1187 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1188 int, existing theories and proof scripts may require a few additional
  1189 type constraints;
  1190 
  1191 * integer division and remainder can now be performed on constant
  1192 arguments;
  1193 
  1194 * many properties of integer multiplication, division and remainder
  1195 are now available;
  1196 
  1197 * An interface to the Stanford Validity Checker (SVC) is available through the
  1198 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1199 are proved automatically.  SVC must be installed separately, and its results
  1200 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1201 invocation of the underlying oracle).  For SVC see
  1202   http://verify.stanford.edu/SVC
  1203 
  1204 * IsaMakefile: the HOL-Real target now builds an actual image;
  1205 
  1206 
  1207 ** HOL misc **
  1208 
  1209 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1210 (in Isabelle/Isar) -- by Gertrud Bauer;
  1211 
  1212 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1213 analysis for assembly languages with subtypes;
  1214 
  1215 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1216 -- avoids syntactic ambiguities and treats state, transition, and
  1217 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1218 changed syntax and (many) tactics;
  1219 
  1220 * HOL/inductive: Now also handles more general introduction rules such
  1221   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1222   theorems are now maintained within the theory (maintained via the
  1223   "mono" attribute);
  1224 
  1225 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1226   (using function types) such as
  1227 
  1228   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1229 
  1230 * HOL/record: record_simproc (part of the default simpset) takes care
  1231 of selectors applied to updated records; record_split_tac is no longer
  1232 part of the default claset; update_defs may now be removed from the
  1233 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1234 
  1235   claset_ref () := claset() addSWrapper record_split_wrapper;
  1236   Delsimprocs [record_simproc]
  1237 
  1238 * HOL/typedef: fixed type inference for representing set; type
  1239 arguments now have to occur explicitly on the rhs as type constraints;
  1240 
  1241 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1242 names rather than an ML expression;
  1243 
  1244 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1245 supplied later.  Program schemes can be defined, such as
  1246     "While B C s = (if B s then While B C (C s) else s)"
  1247 where the well-founded relation can be chosen after B and C have been given.
  1248 
  1249 * HOL/List: the constructors of type list are now Nil and Cons;
  1250 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1251 course, ML tools referring to List.list.op # etc. have to be adapted;
  1252 
  1253 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1254 disabled by default; run isabelle with option -m HOL to get back to
  1255 the original Gordon/HOL-style output;
  1256 
  1257 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1258 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1259 
  1260 * HOL basic syntax simplified (more orthogonal): all variants of
  1261 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1262 Eps operator is provided as well: "SOME x. P[x]";
  1263 
  1264 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1265 
  1266 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1267 thus available for user theories;
  1268 
  1269 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1270 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1271 time;
  1272 
  1273 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1274 several times and then mp;
  1275 
  1276 
  1277 *** LK ***
  1278 
  1279 * the notation <<...>> is now available as a notation for sequences of
  1280 formulas;
  1281 
  1282 * the simplifier is now installed
  1283 
  1284 * the axiom system has been generalized (thanks to Soren Heilmann)
  1285 
  1286 * the classical reasoner now has a default rule database
  1287 
  1288 
  1289 *** ZF ***
  1290 
  1291 * new primrec section allows primitive recursive functions to be given
  1292 directly (as in HOL) over datatypes and the natural numbers;
  1293 
  1294 * new tactics induct_tac and exhaust_tac for induction (or case
  1295 analysis) over datatypes and the natural numbers;
  1296 
  1297 * the datatype declaration of type T now defines the recursor T_rec;
  1298 
  1299 * simplification automatically does freeness reasoning for datatype
  1300 constructors;
  1301 
  1302 * automatic type-inference, with AddTCs command to insert new
  1303 type-checking rules;
  1304 
  1305 * datatype introduction rules are now added as Safe Introduction rules
  1306 to the claset;
  1307 
  1308 * the syntax "if P then x else y" is now available in addition to
  1309 if(P,x,y);
  1310 
  1311 
  1312 *** Internal programming interfaces ***
  1313 
  1314 * tuned simplifier trace output; new flag debug_simp;
  1315 
  1316 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1317 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1318 
  1319 * AxClass.axclass_tac lost the theory argument;
  1320 
  1321 * tuned current_goals_markers semantics: begin / end goal avoids
  1322 printing empty lines;
  1323 
  1324 * removed prs and prs_fn hook, which was broken because it did not
  1325 include \n in its semantics, forcing writeln to add one
  1326 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1327 string -> unit if you really want to output text without newline;
  1328 
  1329 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1330 plain output, interface builders may have to enable 'isabelle_font'
  1331 mode to get Isabelle font glyphs as before;
  1332 
  1333 * refined token_translation interface; INCOMPATIBILITY: output length
  1334 now of type real instead of int;
  1335 
  1336 * theory loader actions may be traced via new ThyInfo.add_hook
  1337 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1338 your own database of information attached to *whole* theories -- as
  1339 opposed to intra-theory data slots offered via TheoryDataFun;
  1340 
  1341 * proper handling of dangling sort hypotheses (at last!);
  1342 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1343 extra sort hypotheses that can be witnessed from the type signature;
  1344 the force_strip_shyps flag is gone, any remaining shyps are simply
  1345 left in the theorem (with a warning issued by strip_shyps_warning);
  1346 
  1347 
  1348 
  1349 New in Isabelle98-1 (October 1998)
  1350 ----------------------------------
  1351 
  1352 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1353 
  1354 * several changes of automated proof tools;
  1355 
  1356 * HOL: major changes to the inductive and datatype packages, including
  1357 some minor incompatibilities of theory syntax;
  1358 
  1359 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1360 called `inj_on';
  1361 
  1362 * HOL: removed duplicate thms in Arith:
  1363   less_imp_add_less  should be replaced by  trans_less_add1
  1364   le_imp_add_le      should be replaced by  trans_le_add1
  1365 
  1366 * HOL: unary minus is now overloaded (new type constraints may be
  1367 required);
  1368 
  1369 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1370 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1371 now taken as an integer constant.
  1372 
  1373 * Pure: ML function 'theory_of' renamed to 'theory';
  1374 
  1375 
  1376 *** Proof tools ***
  1377 
  1378 * Simplifier:
  1379   1. Asm_full_simp_tac is now more aggressive.
  1380      1. It will sometimes reorient premises if that increases their power to
  1381         simplify.
  1382      2. It does no longer proceed strictly from left to right but may also
  1383         rotate premises to achieve further simplification.
  1384      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1385      old Asm_full_simp_tac in that it does not rotate premises.
  1386   2. The simplifier now knows a little bit about nat-arithmetic.
  1387 
  1388 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1389 allows for selected deletion of wrappers, by introduction of names for
  1390 wrapper functionals.  This implies that addbefore, addSbefore,
  1391 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1392 and that adding two tactics with the same name overwrites the first
  1393 one (emitting a warning).
  1394   type wrapper = (int -> tactic) -> (int -> tactic)
  1395   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1396   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1397   delWrapper, delSWrapper: claset *  string            -> claset
  1398   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1399 
  1400 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1401 semantics; addbefore now affects only the unsafe part of step_tac
  1402 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1403 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1404 by Force_tac;
  1405 
  1406 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1407 compWrapper; added safe wrapper (and access functions for it);
  1408 
  1409 * HOL/split_all_tac is now much faster and fails if there is nothing
  1410 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1411 and the names of the automatically generated variables have changed.
  1412 split_all_tac has moved within claset() from unsafe wrappers to safe
  1413 wrappers, which means that !!-bound variables are split much more
  1414 aggressively, and safe_tac and clarify_tac now split such variables.
  1415 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1416 Note: the same holds for record_split_tac, which does the job of
  1417 split_all_tac for record fields.
  1418 
  1419 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1420 permanently to the default simpset using Addsplits just like
  1421 Addsimps. They can be removed via Delsplits just like
  1422 Delsimps. Lower-case versions are also available.
  1423 
  1424 * HOL/Simplifier: The rule split_if is now part of the default
  1425 simpset. This means that the simplifier will eliminate all occurrences
  1426 of if-then-else in the conclusion of a goal. To prevent this, you can
  1427 either remove split_if completely from the default simpset by
  1428 `Delsplits [split_if]' or remove it in a specific call of the
  1429 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1430 other case splitting rules to/from the default simpset: every datatype
  1431 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1432 t is the name of the datatype).
  1433 
  1434 * Classical reasoner / Simplifier combination: new force_tac (and
  1435 derivatives Force_tac, force) combines rewriting and classical
  1436 reasoning (and whatever other tools) similarly to auto_tac, but is
  1437 aimed to solve the given subgoal completely.
  1438 
  1439 
  1440 *** General ***
  1441 
  1442 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1443 and `goalw': the theory is no longer needed as an explicit argument -
  1444 the current theory context is used; assumptions are no longer returned
  1445 at the ML-level unless one of them starts with ==> or !!; it is
  1446 recommended to convert to these new commands using isatool fixgoal
  1447 (backup your sources first!);
  1448 
  1449 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1450 the current theory context, and 'theory' to lookup stored theories;
  1451 
  1452 * new theory section 'locale' for declaring constants, assumptions and
  1453 definitions that have local scope;
  1454 
  1455 * new theory section 'nonterminals' for purely syntactic types;
  1456 
  1457 * new theory section 'setup' for generic ML setup functions
  1458 (e.g. package initialization);
  1459 
  1460 * the distribution now includes Isabelle icons: see
  1461 lib/logo/isabelle-{small,tiny}.xpm;
  1462 
  1463 * isatool install - install binaries with absolute references to
  1464 ISABELLE_HOME/bin;
  1465 
  1466 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1467 
  1468 * print mode 'emacs' reserved for Isamode;
  1469 
  1470 * support multiple print (ast) translations per constant name;
  1471 
  1472 * theorems involving oracles are now printed with a suffixed [!];
  1473 
  1474 
  1475 *** HOL ***
  1476 
  1477 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1478 
  1479 * HOL/inductive package reorganized and improved: now supports mutual
  1480 definitions such as
  1481 
  1482   inductive EVEN ODD
  1483     intrs
  1484       null "0 : EVEN"
  1485       oddI "n : EVEN ==> Suc n : ODD"
  1486       evenI "n : ODD ==> Suc n : EVEN"
  1487 
  1488 new theorem list "elims" contains an elimination rule for each of the
  1489 recursive sets; inductive definitions now handle disjunctive premises
  1490 correctly (also ZF);
  1491 
  1492 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1493 "mutual_induct" no longer exists - the induction rule is always
  1494 contained in "induct";
  1495 
  1496 
  1497 * HOL/datatype package re-implemented and greatly improved: now
  1498 supports mutually recursive datatypes such as
  1499 
  1500   datatype
  1501     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1502             | SUM ('a aexp) ('a aexp)
  1503             | DIFF ('a aexp) ('a aexp)
  1504             | NUM 'a
  1505   and
  1506     'a bexp = LESS ('a aexp) ('a aexp)
  1507             | AND ('a bexp) ('a bexp)
  1508             | OR ('a bexp) ('a bexp)
  1509 
  1510 as well as indirectly recursive datatypes such as
  1511 
  1512   datatype
  1513     ('a, 'b) term = Var 'a
  1514                   | App 'b ((('a, 'b) term) list)
  1515 
  1516 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1517 induction on mutually / indirectly recursive datatypes.
  1518 
  1519 Primrec equations are now stored in theory and can be accessed via
  1520 <function_name>.simps.
  1521 
  1522 INCOMPATIBILITIES:
  1523 
  1524   - Theories using datatypes must now have theory Datatype as an
  1525     ancestor.
  1526   - The specific <typename>.induct_tac no longer exists - use the
  1527     generic induct_tac instead.
  1528   - natE has been renamed to nat.exhaust - use exhaust_tac
  1529     instead of res_inst_tac ... natE. Note that the variable
  1530     names in nat.exhaust differ from the names in natE, this
  1531     may cause some "fragile" proofs to fail.
  1532   - The theorems split_<typename>_case and split_<typename>_case_asm
  1533     have been renamed to <typename>.split and <typename>.split_asm.
  1534   - Since default sorts of type variables are now handled correctly,
  1535     some datatype definitions may have to be annotated with explicit
  1536     sort constraints.
  1537   - Primrec definitions no longer require function name and type
  1538     of recursive argument.
  1539 
  1540 Consider using isatool fixdatatype to adapt your theories and proof
  1541 scripts to the new package (backup your sources first!).
  1542 
  1543 
  1544 * HOL/record package: considerably improved implementation; now
  1545 includes concrete syntax for record types, terms, updates; theorems
  1546 for surjective pairing and splitting !!-bound record variables; proof
  1547 support is as follows:
  1548 
  1549   1) standard conversions (selectors or updates applied to record
  1550 constructor terms) are part of the standard simpset;
  1551 
  1552   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1553 made part of standard simpset and claset via addIffs;
  1554 
  1555   3) a tactic for record field splitting (record_split_tac) is part of
  1556 the standard claset (addSWrapper);
  1557 
  1558 To get a better idea about these rules you may retrieve them via
  1559 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1560 the name of your record type.
  1561 
  1562 The split tactic 3) conceptually simplifies by the following rule:
  1563 
  1564   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1565 
  1566 Thus any record variable that is bound by meta-all will automatically
  1567 blow up into some record constructor term, consequently the
  1568 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1569 solve record problems automatically.
  1570 
  1571 
  1572 * reorganized the main HOL image: HOL/Integ and String loaded by
  1573 default; theory Main includes everything;
  1574 
  1575 * automatic simplification of integer sums and comparisons, using cancellation;
  1576 
  1577 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1578 
  1579 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1580 
  1581 * many new identities for unions, intersections, set difference, etc.;
  1582 
  1583 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1584 called split_if, split_split, split_sum_case and split_nat_case (to go
  1585 with add/delsplits);
  1586 
  1587 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1588 (?x::unit) = (); this is made part of the default simpset, which COULD
  1589 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1590 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1591 unit_abs_eta_conv is added in order to counter the effect of
  1592 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1593 %u.f();
  1594 
  1595 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1596 makes more sense);
  1597 
  1598 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1599   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1600   disjointness reasoning but breaking a few old proofs.
  1601 
  1602 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1603 to 'converse' from 'inverse' (for compatibility with ZF and some
  1604 literature);
  1605 
  1606 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1607 the well-founded relation;
  1608 
  1609 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1610     Compl A.  The "Compl" syntax remains available as input syntax for this
  1611     release ONLY.
  1612 
  1613 * HOL/Update: new theory of function updates:
  1614     f(a:=b) == %x. if x=a then b else f x
  1615 may also be iterated as in f(a:=b,c:=d,...);
  1616 
  1617 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1618 
  1619 * HOL/List:
  1620   - new function list_update written xs[i:=v] that updates the i-th
  1621     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1622   - new function `upt' written [i..j(] which generates the list
  1623     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1624     bound write [i..j], which is a shorthand for [i..j+1(].
  1625   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1626 
  1627 * HOL/Arith:
  1628   - removed 'pred' (predecessor) function;
  1629   - generalized some theorems about n-1;
  1630   - many new laws about "div" and "mod";
  1631   - new laws about greatest common divisors (see theory ex/Primes);
  1632 
  1633 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1634 instead of "inverse";
  1635 
  1636 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1637   of the multiset ordering;
  1638 
  1639 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1640   (not included by default);
  1641 
  1642 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1643 
  1644 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1645   programs, i.e. different program variables may have different types.
  1646 
  1647 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1648   [previously, this check worked only if the rewrite rule was unconditional]
  1649   Now rew can involve either definitions or equalities (either == or =).
  1650 
  1651 
  1652 *** ZF ***
  1653 
  1654 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1655   only the theorems proved on ZF.ML;
  1656 
  1657 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1658   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1659   disjointness reasoning but breaking a few old proofs.
  1660 
  1661 * ZF/Update: new theory of function updates
  1662     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1663   may also be iterated as in f(a:=b,c:=d,...);
  1664 
  1665 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1666 
  1667 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1668   [previously, this check worked only if the rewrite rule was unconditional]
  1669   Now rew can involve either definitions or equalities (either == or =).
  1670 
  1671 * case_tac provided for compatibility with HOL
  1672     (like the old excluded_middle_tac, but with subgoals swapped)
  1673 
  1674 
  1675 *** Internal programming interfaces ***
  1676 
  1677 * Pure: several new basic modules made available for general use, see
  1678 also src/Pure/README;
  1679 
  1680 * improved the theory data mechanism to support encapsulation (data
  1681 kind name replaced by private Object.kind, acting as authorization
  1682 key); new type-safe user interface via functor TheoryDataFun; generic
  1683 print_data function becomes basically useless;
  1684 
  1685 * removed global_names compatibility flag -- all theory declarations
  1686 are qualified by default;
  1687 
  1688 * module Pure/Syntax now offers quote / antiquote translation
  1689 functions (useful for Hoare logic etc. with implicit dependencies);
  1690 see HOL/ex/Antiquote for an example use;
  1691 
  1692 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1693 cterm -> thm;
  1694 
  1695 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1696 subgoal;
  1697 
  1698 * Display.print_goals function moved to Locale.print_goals;
  1699 
  1700 * standard print function for goals supports current_goals_markers
  1701 variable for marking begin of proof, end of proof, start of goal; the
  1702 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1703 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1704 for example;
  1705 
  1706 
  1707 
  1708 New in Isabelle98 (January 1998)
  1709 --------------------------------
  1710 
  1711 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1712 
  1713 * changed lexical syntax of terms / types: dots made part of long
  1714 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1715 
  1716 * simpset (and claset) reference variable replaced by functions
  1717 simpset / simpset_ref;
  1718 
  1719 * no longer supports theory aliases (via merge) and non-trivial
  1720 implicit merge of thms' signatures;
  1721 
  1722 * most internal names of constants changed due to qualified names;
  1723 
  1724 * changed Pure/Sequence interface (see Pure/seq.ML);
  1725 
  1726 
  1727 *** General Changes ***
  1728 
  1729 * hierachically structured name spaces (for consts, types, axms, thms
  1730 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1731 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1732 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1733 long_names for fully qualified output names; NOTE: ML programs
  1734 (special tactics, packages etc.) referring to internal names may have
  1735 to be adapted to cope with fully qualified names; in case of severe
  1736 backward campatibility problems try setting 'global_names' at compile
  1737 time to have enrything declared within a flat name space; one may also
  1738 fine tune name declarations in theories via the 'global' and 'local'
  1739 section;
  1740 
  1741 * reimplemented the implicit simpset and claset using the new anytype
  1742 data filed in signatures; references simpset:simpset ref etc. are
  1743 replaced by functions simpset:unit->simpset and
  1744 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1745 to patch your ML files accordingly;
  1746 
  1747 * HTML output now includes theory graph data for display with Java
  1748 applet or isatool browser; data generated automatically via isatool
  1749 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1750 
  1751 * defs may now be conditional; improved rewrite_goals_tac to handle
  1752 conditional equations;
  1753 
  1754 * defs now admits additional type arguments, using TYPE('a) syntax;
  1755 
  1756 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1757 creates a new theory node; implicit merge of thms' signatures is
  1758 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1759 transfer:theory->thm->thm in (rare) cases;
  1760 
  1761 * improved handling of draft signatures / theories; draft thms (and
  1762 ctyps, cterms) are automatically promoted to real ones;
  1763 
  1764 * slightly changed interfaces for oracles: admit many per theory, named
  1765 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1766 
  1767 * print_goals: optional output of const types (set show_consts and
  1768 show_types);
  1769 
  1770 * improved output of warnings (###) and errors (***);
  1771 
  1772 * subgoal_tac displays a warning if the new subgoal has type variables;
  1773 
  1774 * removed old README and Makefiles;
  1775 
  1776 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1777 
  1778 * removed obsolete init_pps and init_database;
  1779 
  1780 * deleted the obsolete tactical STATE, which was declared by
  1781     fun STATE tacfun st = tacfun st st;
  1782 
  1783 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1784 (which abbreviates $HOME);
  1785 
  1786 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1787 use isatool fixseq to adapt your ML programs (this works for fully
  1788 qualified references to the Sequence structure only!);
  1789 
  1790 * use_thy no longer requires writable current directory; it always
  1791 reloads .ML *and* .thy file, if either one is out of date;
  1792 
  1793 
  1794 *** Classical Reasoner ***
  1795 
  1796 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1797 tactics that use classical reasoning to simplify a subgoal without
  1798 splitting it into several subgoals;
  1799 
  1800 * Safe_tac: like safe_tac but uses the default claset;
  1801 
  1802 
  1803 *** Simplifier ***
  1804 
  1805 * added simplification meta rules:
  1806     (asm_)(full_)simplify: simpset -> thm -> thm;
  1807 
  1808 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1809 logics (again);
  1810 
  1811 * added prems argument to simplification procedures;
  1812 
  1813 * HOL, FOL, ZF: added infix function `addsplits':
  1814   instead of `<simpset> setloop (split_tac <thms>)'
  1815   you can simply write `<simpset> addsplits <thms>'
  1816 
  1817 
  1818 *** Syntax ***
  1819 
  1820 * TYPE('a) syntax for type reflection terms;
  1821 
  1822 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1823 
  1824 * pretty printer: changed order of mixfix annotation preference (again!);
  1825 
  1826 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1827 
  1828 
  1829 *** HOL ***
  1830 
  1831 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1832   with `addloop' of the simplifier to faciliate case splitting in premises.
  1833 
  1834 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1835 
  1836 * HOL/Auth: new protocol proofs including some for the Internet
  1837   protocol TLS;
  1838 
  1839 * HOL/Map: new theory of `maps' a la VDM;
  1840 
  1841 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1842 cancelling out common nat summands from =, <, <= (in)equalities, or
  1843 differences; simplification procedures nat_cancel_factor for
  1844 cancelling common factor from =, <, <= (in)equalities over natural
  1845 sums; nat_cancel contains both kinds of procedures, it is installed by
  1846 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1847 
  1848 * HOL/simplifier: terms of the form
  1849   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1850   are rewritten to
  1851   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1852   and those of the form
  1853   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1854   are rewritten to
  1855   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1856 
  1857 * HOL/datatype
  1858   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1859 
  1860   P(t_case f1 ... fn x) =
  1861      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1862         ...
  1863        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1864      )
  1865 
  1866   and a theorem `split_t_case_asm' of the form
  1867 
  1868   P(t_case f1 ... fn x) =
  1869     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1870         ...
  1871        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1872      )
  1873   which can be added to a simpset via `addsplits'. The existing theorems
  1874   expand_list_case and expand_option_case have been renamed to
  1875   split_list_case and split_option_case.
  1876 
  1877 * HOL/Arithmetic:
  1878   - `pred n' is automatically converted to `n-1'.
  1879     Users are strongly encouraged not to use `pred' any longer,
  1880     because it will disappear altogether at some point.
  1881   - Users are strongly encouraged to write "0 < n" rather than
  1882     "n ~= 0". Theorems and proof tools have been modified towards this
  1883     `standard'.
  1884 
  1885 * HOL/Lists:
  1886   the function "set_of_list" has been renamed "set" (and its theorems too);
  1887   the function "nth" now takes its arguments in the reverse order and
  1888   has acquired the infix notation "!" as in "xs!n".
  1889 
  1890 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1891 
  1892 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1893   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1894 
  1895 * HOL/record: extensible records with schematic structural subtyping
  1896 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1897 still lacks various theorems and concrete record syntax;
  1898 
  1899 
  1900 *** HOLCF ***
  1901 
  1902 * removed "axioms" and "generated by" sections;
  1903 
  1904 * replaced "ops" section by extended "consts" section, which is capable of
  1905   handling the continuous function space "->" directly;
  1906 
  1907 * domain package:
  1908   . proves theorems immediately and stores them in the theory,
  1909   . creates hierachical name space,
  1910   . now uses normal mixfix annotations (instead of cinfix...),
  1911   . minor changes to some names and values (for consistency),
  1912   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1913   . separator between mutual domain defs: changed "," to "and",
  1914   . improved handling of sort constraints;  now they have to
  1915     appear on the left-hand side of the equations only;
  1916 
  1917 * fixed LAM <x,y,zs>.b syntax;
  1918 
  1919 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1920 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1921 
  1922 
  1923 *** FOL and ZF ***
  1924 
  1925 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1926   with `addloop' of the simplifier to faciliate case splitting in premises.
  1927 
  1928 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1929 in HOL, they strip ALL and --> from proved theorems;
  1930 
  1931 
  1932 
  1933 New in Isabelle94-8 (May 1997)
  1934 ------------------------------
  1935 
  1936 *** General Changes ***
  1937 
  1938 * new utilities to build / run / maintain Isabelle etc. (in parts
  1939 still somewhat experimental); old Makefiles etc. still functional;
  1940 
  1941 * new 'Isabelle System Manual';
  1942 
  1943 * INSTALL text, together with ./configure and ./build scripts;
  1944 
  1945 * reimplemented type inference for greater efficiency, better error
  1946 messages and clean internal interface;
  1947 
  1948 * prlim command for dealing with lots of subgoals (an easier way of
  1949 setting goals_limit);
  1950 
  1951 
  1952 *** Syntax ***
  1953 
  1954 * supports alternative (named) syntax tables (parser and pretty
  1955 printer); internal interface is provided by add_modesyntax(_i);
  1956 
  1957 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1958 be used in conjunction with the Isabelle symbol font; uses the
  1959 "symbols" syntax table;
  1960 
  1961 * added token_translation interface (may translate name tokens in
  1962 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1963 the current print_mode); IMPORTANT: user print translation functions
  1964 are responsible for marking newly introduced bounds
  1965 (Syntax.mark_boundT);
  1966 
  1967 * token translations for modes "xterm" and "xterm_color" that display
  1968 names in bold, underline etc. or colors (which requires a color
  1969 version of xterm);
  1970 
  1971 * infixes may now be declared with names independent of their syntax;
  1972 
  1973 * added typed_print_translation (like print_translation, but may
  1974 access type of constant);
  1975 
  1976 
  1977 *** Classical Reasoner ***
  1978 
  1979 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  1980 some limitations.  Blast_tac...
  1981   + ignores addss, addbefore, addafter; this restriction is intrinsic
  1982   + ignores elimination rules that don't have the correct format
  1983         (the conclusion MUST be a formula variable)
  1984   + ignores types, which can make HOL proofs fail
  1985   + rules must not require higher-order unification, e.g. apply_type in ZF
  1986     [message "Function Var's argument not a bound variable" relates to this]
  1987   + its proof strategy is more general but can actually be slower
  1988 
  1989 * substitution with equality assumptions no longer permutes other
  1990 assumptions;
  1991 
  1992 * minor changes in semantics of addafter (now called addaltern); renamed
  1993 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  1994 (and access functions for it);
  1995 
  1996 * improved combination of classical reasoner and simplifier:
  1997   + functions for handling clasimpsets
  1998   + improvement of addss: now the simplifier is called _after_ the
  1999     safe steps.
  2000   + safe variant of addss called addSss: uses safe simplifications
  2001     _during_ the safe steps. It is more complete as it allows multiple
  2002     instantiations of unknowns (e.g. with slow_tac).
  2003 
  2004 *** Simplifier ***
  2005 
  2006 * added interface for simplification procedures (functions that
  2007 produce *proven* rewrite rules on the fly, depending on current
  2008 redex);
  2009 
  2010 * ordering on terms as parameter (used for ordered rewriting);
  2011 
  2012 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2013 
  2014 * the solver is now split into a safe and an unsafe part.
  2015 This should be invisible for the normal user, except that the
  2016 functions setsolver and addsolver have been renamed to setSolver and
  2017 addSolver; added safe_asm_full_simp_tac;
  2018 
  2019 
  2020 *** HOL ***
  2021 
  2022 * a generic induction tactic `induct_tac' which works for all datatypes and
  2023 also for type `nat';
  2024 
  2025 * a generic case distinction tactic `exhaust_tac' which works for all
  2026 datatypes and also for type `nat';
  2027 
  2028 * each datatype comes with a function `size';
  2029 
  2030 * patterns in case expressions allow tuple patterns as arguments to
  2031 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2032 
  2033 * primrec now also works with type nat;
  2034 
  2035 * recdef: a new declaration form, allows general recursive functions to be
  2036 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2037 
  2038 * the constant for negation has been renamed from "not" to "Not" to
  2039 harmonize with FOL, ZF, LK, etc.;
  2040 
  2041 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2042 infinite lists;
  2043 
  2044 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2045 
  2046 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2047 problems in commutative rings, using axiomatic type classes for + and *;
  2048 
  2049 * more examples in HOL/MiniML and HOL/Auth;
  2050 
  2051 * more default rewrite rules for quantifiers, union/intersection;
  2052 
  2053 * a new constant `arbitrary == @x.False';
  2054 
  2055 * HOLCF/IOA replaces old HOL/IOA;
  2056 
  2057 * HOLCF changes: derived all rules and arities
  2058   + axiomatic type classes instead of classes
  2059   + typedef instead of faking type definitions
  2060   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2061   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2062   + eliminated the types void, one, tr
  2063   + use unit lift and bool lift (with translations) instead of one and tr
  2064   + eliminated blift from Lift3.thy (use Def instead of blift)
  2065   all eliminated rules are derived as theorems --> no visible changes ;
  2066 
  2067 
  2068 *** ZF ***
  2069 
  2070 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2071 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2072 as ZF_cs addSIs [equalityI];
  2073 
  2074 
  2075 
  2076 New in Isabelle94-7 (November 96)
  2077 ---------------------------------
  2078 
  2079 * allowing negative levels (as offsets) in prlev and choplev;
  2080 
  2081 * super-linear speedup for large simplifications;
  2082 
  2083 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2084 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2085 FAIL); can suppress it using the command Delsimps (ex_simps @
  2086 all_simps); De Morgan laws are also now included, by default;
  2087 
  2088 * improved printing of ==>  :  ~:
  2089 
  2090 * new object-logic "Sequents" adds linear logic, while replacing LK
  2091 and Modal (thanks to Sara Kalvala);
  2092 
  2093 * HOL/Auth: correctness proofs for authentication protocols;
  2094 
  2095 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2096 examples on HOL/Auth);
  2097 
  2098 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2099 the rewriter and classical reasoner simultaneously;
  2100 
  2101 * function uresult no longer returns theorems in "standard" format;
  2102 regain previous version by: val uresult = standard o uresult;
  2103 
  2104 
  2105 
  2106 New in Isabelle94-6
  2107 -------------------
  2108 
  2109 * oracles -- these establish an interface between Isabelle and trusted
  2110 external reasoners, which may deliver results as theorems;
  2111 
  2112 * proof objects (in particular record all uses of oracles);
  2113 
  2114 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2115 
  2116 * "constdefs" section in theory files;
  2117 
  2118 * "primrec" section (HOL) no longer requires names;
  2119 
  2120 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2121 
  2122 
  2123 
  2124 New in Isabelle94-5
  2125 -------------------
  2126 
  2127 * reduced space requirements;
  2128 
  2129 * automatic HTML generation from theories;
  2130 
  2131 * theory files no longer require "..." (quotes) around most types;
  2132 
  2133 * new examples, including two proofs of the Church-Rosser theorem;
  2134 
  2135 * non-curried (1994) version of HOL is no longer distributed;
  2136 
  2137 
  2138 
  2139 New in Isabelle94-4
  2140 -------------------
  2141 
  2142 * greatly reduced space requirements;
  2143 
  2144 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2145 
  2146 * searchable theorem database (see the section "Retrieving theorems" on
  2147 page 8 of the Reference Manual);
  2148 
  2149 * new examples, including Grabczewski's monumental case study of the
  2150 Axiom of Choice;
  2151 
  2152 * The previous version of HOL renamed to Old_HOL;
  2153 
  2154 * The new version of HOL (previously called CHOL) uses a curried syntax
  2155 for functions.  Application looks like f a b instead of f(a,b);
  2156 
  2157 * Mutually recursive inductive definitions finally work in HOL;
  2158 
  2159 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2160 translates to the operator "split";
  2161 
  2162 
  2163 
  2164 New in Isabelle94-3
  2165 -------------------
  2166 
  2167 * new infix operator, addss, allowing the classical reasoner to
  2168 perform simplification at each step of its search.  Example:
  2169         fast_tac (cs addss ss)
  2170 
  2171 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2172 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2173 look like (a,b) instead of <a,b>;
  2174 
  2175 * PLEASE NOTE: CHOL will eventually replace HOL!
  2176 
  2177 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2178 It translates to the operator "split".  A new theory of integers is available;
  2179 
  2180 * In ZF, integer numerals now denote two's-complement binary integers.
  2181 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2182 
  2183 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2184 of the Axiom of Choice;
  2185 
  2186 
  2187 
  2188 New in Isabelle94-2
  2189 -------------------
  2190 
  2191 * Significantly faster resolution;
  2192 
  2193 * the different sections in a .thy file can now be mixed and repeated
  2194 freely;
  2195 
  2196 * Database of theorems for FOL, HOL and ZF.  New
  2197 commands including qed, qed_goal and bind_thm store theorems in the database.
  2198 
  2199 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2200 a given theory (thms_of), or find out what theory a theorem was proved in
  2201 (theory_of_thm);
  2202 
  2203 * Bugs fixed in the inductive definition and datatype packages;
  2204 
  2205 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2206 and HOL_dup_cs obsolete;
  2207 
  2208 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2209 have been removed;
  2210 
  2211 * Simpler definition of function space in ZF;
  2212 
  2213 * new results about cardinal and ordinal arithmetic in ZF;
  2214 
  2215 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2216 types;
  2217 
  2218 
  2219 $Id$