NEWS
author paulson
Thu Feb 20 11:09:48 2003 +0100 (2003-02-20)
changeset 13824 e4d8dea6dfc2
parent 13815 0832792725db
child 13829 af0218406395
permissions -rw-r--r--
minor updates to pre-2002 release
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** General ***
     8 
     9 * Provers/simplifier:
    10 
    11   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
    12     Assumptions are now subject to complete mutual simplification,
    13     not just from left to right. The simplifier now preserves
    14     the order of assumptions.
    15 
    16     Potential INCOMPATIBILITY:
    17 
    18     -- simp sometimes diverges where the old version did
    19        not, e.g. invoking simp on the goal
    20 
    21         [| P (f x); y = x; f x = f y |] ==> Q
    22 
    23        now gives rise to the infinite reduction sequence
    24 
    25         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
    26 
    27        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
    28        kind of problem.
    29 
    30     -- Tactics combining classical reasoner and simplification (such as auto)
    31        are also affected by this change, because many of them rely on
    32        simp. They may sometimes diverge as well or yield a different numbers
    33        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
    34        in case of problems. Sometimes subsequent calls to the classical
    35        reasoner will fail because a preceeding call to the simplifier too
    36        eagerly simplified the goal, e.g. deleted redundant premises.
    37 
    38   - The simplifier trace now shows the names of the applied rewrite rules
    39 
    40 * Pure: New flag for triggering if the overall goal of a proof state should
    41 be printed:
    42    PG menu: Isabelle/Isar -> Settigs -> Show Main Goal
    43 (ML: Proof.show_main_goal).
    44 
    45 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
    46 rules whose conclusion matches subgoal 1:
    47       PG menu: Isabelle/Isar -> Show me -> matching rules
    48 The rules are ordered by how closely they match the subgoal.
    49 In particular, rules that solve a subgoal outright are displayed first
    50 (or rather last, the way they are printed).
    51 (ML: ProofGeneral.print_intros())
    52 
    53 * Pure: New flag trace_unify_fail causes unification to print
    54 diagnostic information (PG: in trace buffer) when it fails. This is
    55 useful for figuring out why single step proofs like rule, erule or
    56 assumption failed.
    57 
    58 * Pure: Locale specifications now produce predicate definitions
    59 according to the body of text (covering assumptions modulo local
    60 definitions); predicate "loc_axioms" covers newly introduced text,
    61 while "loc" is cumulative wrt. all included locale expressions; the
    62 latter view is presented only on export into the global theory
    63 context; potential INCOMPATIBILITY, use "(open)" option to fall back
    64 on the old view without predicates;
    65 
    66 * Pure: predefined locales "var" and "struct" are useful for sharing
    67 parameters (as in CASL, for example); just specify something like
    68 ``var x + var y + struct M'' as import;
    69 
    70 * Pure: improved thms_containing: proper indexing of facts instead of
    71 raw theorems; check validity of results wrt. current name space;
    72 include local facts of proof configuration (also covers active
    73 locales), cover fixed variables in index; may use "_" in term
    74 specification; an optional limit for the number of printed facts may
    75 be given (the default is 40);
    76 
    77 * Pure: disallow duplicate fact bindings within new-style theory files
    78 (batch-mode only);
    79 
    80 * Provers: improved induct method: assumptions introduced by case
    81 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
    82 the goal statement); "foo" still refers to all facts collectively;
    83 
    84 * Provers: the function blast.overloaded has been removed: all constants
    85 are regarded as potentially overloaded, which improves robustness in exchange
    86 for slight decrease in efficiency;
    87 
    88 * Provers/linorder: New generic prover for transitivity reasoning over
    89 linear orders.  Note: this prover is not efficient!
    90 
    91 * Isar: preview of problems to finish 'show' now produce an error
    92 rather than just a warning (in interactive mode);
    93 
    94 
    95 *** HOL ***
    96 
    97 * GroupTheory: new, experimental summation operator for abelian groups.
    98 
    99 * New tactic "trans_tac" and method "trans" instantiate
   100 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   101 "<=", "<" and "="). 
   102 
   103 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main 
   104 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   105 
   106 * 'typedef' command has new option "open" to suppress the set
   107 definition;
   108 
   109 * functions Min and Max on finite sets have been introduced (theory
   110 Finite_Set);
   111 
   112 * attribute [symmetric] now works for relations as well; it turns
   113 (x,y) : R^-1 into (y,x) : R, and vice versa;
   114 
   115 * arith(_tac) now produces a counter example if it cannot prove a theorem.
   116   In ProofGeneral the counter example appears in the trace buffer.
   117 
   118 * arith(_tac) does now know about div k and mod k where k is a numeral
   119 of type nat or int. It can solve simple goals like
   120 
   121   "0 < n ==> n div 2 < (n::nat)"
   122 
   123 but fails if divisibility plays a role like in
   124 
   125   "n div 2 + (n+1) div 2 = (n::nat)"
   126 
   127 * simp's arithmetic capabilities have been enhanced a bit: it now
   128 takes ~= in premises into account (by performing a case split);
   129 
   130 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   131 are distributed over a sum of terms;
   132 
   133 * induct over a !!-quantified statement (say !!x1..xn):
   134   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   135 
   136 * GroupTheory: converted to Isar theories, using locales with implicit structures;
   137 
   138 * Real/HahnBanach: updated and adapted to locales;
   139 
   140 
   141 *** ZF ***
   142 
   143 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   144 universe, etc.);
   145 
   146 * Main ZF: many theories converted to new-style format;
   147 
   148 
   149 *** ML ***
   150 
   151 * Pure: Tactic.prove provides sane interface for internal proofs;
   152 omits the infamous "standard" operation, so this is more appropriate
   153 than prove_goalw_cterm in many situations (e.g. in simprocs);
   154 
   155 * Pure: improved error reporting of simprocs;
   156 
   157 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   158 up simprocs;
   159 
   160 
   161 
   162 New in Isabelle2002 (March 2002)
   163 --------------------------------
   164 
   165 *** Document preparation ***
   166 
   167 * greatly simplified document preparation setup, including more
   168 graceful interpretation of isatool usedir -i/-d/-D options, and more
   169 instructive isatool mkdir; users should basically be able to get
   170 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   171 users may run a separate document processing stage manually like this:
   172 "isatool usedir -D output HOL Test && isatool document Test/output";
   173 
   174 * theory dependency graph may now be incorporated into documents;
   175 isatool usedir -g true will produce session_graph.eps/.pdf for use
   176 with \includegraphics of LaTeX;
   177 
   178 * proper spacing of consecutive markup elements, especially text
   179 blocks after section headings;
   180 
   181 * support bold style (for single symbols only), input syntax is like
   182 this: "\<^bold>\<alpha>" or "\<^bold>A";
   183 
   184 * \<bullet> is now output as bold \cdot by default, which looks much
   185 better in printed text;
   186 
   187 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   188 note that these symbols are currently unavailable in Proof General /
   189 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   190 
   191 * isatool latex no longer depends on changed TEXINPUTS, instead
   192 isatool document copies the Isabelle style files to the target
   193 location;
   194 
   195 
   196 *** Isar ***
   197 
   198 * Pure/Provers: improved proof by cases and induction;
   199   - 'case' command admits impromptu naming of parameters (such as
   200     "case (Suc n)");
   201   - 'induct' method divinates rule instantiation from the inductive
   202     claim; no longer requires excessive ?P bindings for proper
   203     instantiation of cases;
   204   - 'induct' method properly enumerates all possibilities of set/type
   205     rules; as a consequence facts may be also passed through *type*
   206     rules without further ado;
   207   - 'induct' method now derives symbolic cases from the *rulified*
   208     rule (before it used to rulify cases stemming from the internal
   209     atomized version); this means that the context of a non-atomic
   210     statement becomes is included in the hypothesis, avoiding the
   211     slightly cumbersome show "PROP ?case" form;
   212   - 'induct' may now use elim-style induction rules without chaining
   213     facts, using ``missing'' premises from the goal state; this allows
   214     rules stemming from inductive sets to be applied in unstructured
   215     scripts, while still benefitting from proper handling of non-atomic
   216     statements; NB: major inductive premises need to be put first, all
   217     the rest of the goal is passed through the induction;
   218   - 'induct' proper support for mutual induction involving non-atomic
   219     rule statements (uses the new concept of simultaneous goals, see
   220     below);
   221   - append all possible rule selections, but only use the first
   222     success (no backtracking);
   223   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   224   - undeclared rule case names default to numbers 1, 2, 3, ...;
   225   - added 'print_induct_rules' (covered by help item in recent Proof
   226     General versions);
   227   - moved induct/cases attributes to Pure, methods to Provers;
   228   - generic method setup instantiated for FOL and HOL;
   229 
   230 * Pure: support multiple simultaneous goal statements, for example
   231 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   232 meta-level mechanism, this acts as if several individual goals had
   233 been stated separately; in particular common proof methods need to be
   234 repeated in order to cover all claims; note that a single elimination
   235 step is *not* sufficient to establish the two conjunctions, so this
   236 fails:
   237 
   238   assume "A & B" then have A and B ..   (*".." fails*)
   239 
   240 better use "obtain" in situations as above; alternative refer to
   241 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   242 
   243 * Pure: proper integration with ``locales''; unlike the original
   244 version by Florian Kammüller, Isar locales package high-level proof
   245 contexts rather than raw logical ones (e.g. we admit to include
   246 attributes everywhere); operations on locales include merge and
   247 rename; support for implicit arguments (``structures''); simultaneous
   248 type-inference over imports and text; see also HOL/ex/Locales.thy for
   249 some examples;
   250 
   251 * Pure: the following commands have been ``localized'', supporting a
   252 target locale specification "(in name)": 'lemma', 'theorem',
   253 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   254 stored both within the locale and at the theory level (exported and
   255 qualified by the locale name);
   256 
   257 * Pure: theory goals may now be specified in ``long'' form, with
   258 ad-hoc contexts consisting of arbitrary locale elements. for example
   259 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   260 definitions may be given, too); the result is a meta-level rule with
   261 the context elements being discharged in the obvious way;
   262 
   263 * Pure: new proof command 'using' allows to augment currently used
   264 facts after a goal statement ('using' is syntactically analogous to
   265 'apply', but acts on the goal's facts only); this allows chained facts
   266 to be separated into parts given before and after a claim, as in
   267 ``from a and b have C using d and e <proof>'';
   268 
   269 * Pure: renamed "antecedent" case to "rule_context";
   270 
   271 * Pure: new 'judgment' command records explicit information about the
   272 object-logic embedding (used by several tools internally); no longer
   273 use hard-wired "Trueprop";
   274 
   275 * Pure: added 'corollary' command;
   276 
   277 * Pure: fixed 'token_translation' command;
   278 
   279 * Pure: removed obsolete 'exported' attribute;
   280 
   281 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   282 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   283 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   284 
   285 * Pure: method 'atomize' presents local goal premises as object-level
   286 statements (atomic meta-level propositions); setup controlled via
   287 rewrite rules declarations of 'atomize' attribute; example
   288 application: 'induct' method with proper rule statements in improper
   289 proof *scripts*;
   290 
   291 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   292 now consider the syntactic context of assumptions, giving a better
   293 chance to get type-inference of the arguments right (this is
   294 especially important for locales);
   295 
   296 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   297 mode;
   298 
   299 * Pure/obtain: the formal conclusion "thesis", being marked as
   300 ``internal'', may no longer be reference directly in the text;
   301 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   302 situations;
   303 
   304 * Pure: generic 'sym' attribute which declares a rule both as pure
   305 'elim?' and for the 'symmetric' operation;
   306 
   307 * Pure: marginal comments ``--'' may now occur just anywhere in the
   308 text; the fixed correlation with particular command syntax has been
   309 discontinued;
   310 
   311 * Pure: new method 'rules' is particularly well-suited for proof
   312 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   313 but often produces more compact proof terms with less detours;
   314 
   315 * Pure/Provers/classical: simplified integration with pure rule
   316 attributes and methods; the classical "intro?/elim?/dest?"
   317 declarations coincide with the pure ones; the "rule" method no longer
   318 includes classically swapped intros; "intro" and "elim" methods no
   319 longer pick rules from the context; also got rid of ML declarations
   320 AddXIs/AddXEs/AddXDs; all of this has some potential for
   321 INCOMPATIBILITY;
   322 
   323 * Provers/classical: attribute 'swapped' produces classical inversions
   324 of introduction rules;
   325 
   326 * Provers/simplifier: 'simplified' attribute may refer to explicit
   327 rules instead of full simplifier context; 'iff' attribute handles
   328 conditional rules;
   329 
   330 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   331 
   332 * HOL: 'recdef' now fails on unfinished automated proofs, use
   333 "(permissive)" option to recover old behavior;
   334 
   335 * HOL: 'inductive' no longer features separate (collective) attributes
   336 for 'intros' (was found too confusing);
   337 
   338 * HOL: properly declared induction rules less_induct and
   339 wf_induct_rule;
   340 
   341 
   342 *** HOL ***
   343 
   344 * HOL: moved over to sane numeral syntax; the new policy is as
   345 follows:
   346 
   347   - 0 and 1 are polymorphic constants, which are defined on any
   348   numeric type (nat, int, real etc.);
   349 
   350   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   351   binary representation internally;
   352 
   353   - type nat has special constructor Suc, and generally prefers Suc 0
   354   over 1::nat and Suc (Suc 0) over 2::nat;
   355 
   356 This change may cause significant problems of INCOMPATIBILITY; here
   357 are some hints on converting existing sources:
   358 
   359   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   360   entities, so expressions involving "-" (unary or binary minus) need
   361   to be spaced properly;
   362 
   363   - existing occurrences of "1" may need to be constraint "1::nat" or
   364   even replaced by Suc 0; similar for old "2";
   365 
   366   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   367 
   368   - remove all special provisions on numerals in proofs;
   369 
   370 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   371 representation (depends on bin_arith_simps in the default context);
   372 
   373 * HOL: symbolic syntax for x^2 (numeral 2);
   374 
   375 * HOL: the class of all HOL types is now called "type" rather than
   376 "term"; INCOMPATIBILITY, need to adapt references to this type class
   377 in axclass/classes, instance/arities, and (usually rare) occurrences
   378 in typings (of consts etc.); internally the class is called
   379 "HOL.type", ML programs should refer to HOLogic.typeS;
   380 
   381 * HOL/record package improvements:
   382   - new derived operations "fields" to build a partial record section,
   383     "extend" to promote a fixed record to a record scheme, and
   384     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   385     declared as simp by default;
   386   - shared operations ("more", "fields", etc.) now need to be always
   387     qualified) --- potential INCOMPATIBILITY;
   388   - removed "make_scheme" operations (use "make" with "extend") --
   389     INCOMPATIBILITY;
   390   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   391   - provides cases/induct rules for use with corresponding Isar
   392     methods (for concrete records, record schemes, concrete more
   393     parts, and schematic more parts -- in that order);
   394   - internal definitions directly based on a light-weight abstract
   395     theory of product types over typedef rather than datatype;
   396 
   397 * HOL: generic code generator for generating executable ML code from
   398 specifications; specific support for HOL constructs such as inductive
   399 datatypes and sets, as well as recursive functions; can be invoked
   400 via 'generate_code' theory section;
   401 
   402 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   403 
   404 * HOL: consolidated and renamed several theories.  In particular:
   405 	Ord.thy has been absorbed into HOL.thy
   406 	String.thy has been absorbed into List.thy
   407  
   408 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   409 (beware of argument permutation!);
   410 
   411 * HOL: linorder_less_split superseded by linorder_cases;
   412 
   413 * HOL/List: "nodups" renamed to "distinct";
   414 
   415 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   416 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   417   - Ex_def has changed, now need to use some_eq_ex
   418 
   419 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   420 in this (rare) case use:
   421 
   422   delSWrapper "split_all_tac"
   423   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   424 
   425 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   426 MAY FAIL;
   427 
   428 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   429 Isabelle's type classes, ^ on functions and relations has too general
   430 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   431 necessary to attach explicit type constraints;
   432 
   433 * HOL/Relation: the prefix name of the infix "O" has been changed from
   434 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   435 renamed accordingly (eg "compI" -> "rel_compI").
   436 
   437 * HOL: syntax translations now work properly with numerals and records
   438 expressions;
   439 
   440 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   441 of "lam" -- INCOMPATIBILITY;
   442 
   443 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   444 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   445 renamed "Product_Type.unit";
   446 
   447 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   448 
   449 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   450 the "cases" method);
   451 
   452 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   453 Florian Kammüller);
   454 
   455 * HOL/IMP: updated and converted to new-style theory format; several
   456 parts turned into readable document, with proper Isar proof texts and
   457 some explanations (by Gerwin Klein);
   458 
   459 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   460 
   461 * HOL-Hyperreal is now a logic image;
   462 
   463 
   464 *** HOLCF ***
   465 
   466 * Isar: consts/constdefs supports mixfix syntax for continuous
   467 operations;
   468 
   469 * Isar: domain package adapted to new-style theory format, e.g. see
   470 HOLCF/ex/Dnat.thy;
   471 
   472 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   473 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   474 lift.induct_tac, always use UU instead of Undef;
   475 
   476 * HOLCF/IMP: updated and converted to new-style theory;
   477 
   478 
   479 *** ZF ***
   480 
   481 * Isar: proper integration of logic-specific tools and packages,
   482 including theory commands '(co)inductive', '(co)datatype',
   483 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   484 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   485 
   486 * theory Main no longer includes AC; for the Axiom of Choice, base
   487 your theory on Main_ZFC;
   488 
   489 * the integer library now covers quotients and remainders, with many
   490 laws relating division to addition, multiplication, etc.;
   491 
   492 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   493 typeless version of the formalism;
   494 
   495 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   496 format;
   497 
   498 * ZF/Induct: new directory for examples of inductive definitions,
   499 including theory Multiset for multiset orderings; converted to
   500 new-style theory format;
   501 
   502 * ZF: many new theorems about lists, ordinals, etc.;
   503 
   504 
   505 *** General ***
   506 
   507 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   508 variable proof controls level of detail: 0 = no proofs (only oracle
   509 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   510 also ref manual for further ML interfaces;
   511 
   512 * Pure/axclass: removed obsolete ML interface
   513 goal_subclass/goal_arity;
   514 
   515 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   516 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   517 separate tokens, so expressions involving minus need to be spaced
   518 properly;
   519 
   520 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   521 rather than "infixl" or "infixr";
   522 
   523 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   524 sort constraint specifications in type inference; e.g. "x::_::foo"
   525 ensures that the type of "x" is of sort "foo" (but not necessarily a
   526 type variable);
   527 
   528 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   529 control output of nested => (types); the default behavior is
   530 "type_brackets";
   531 
   532 * Pure/syntax: builtin parse translation for "_constify" turns valued
   533 tokens into AST constants;
   534 
   535 * Pure/syntax: prefer later declarations of translations and print
   536 translation functions; potential INCOMPATIBILITY: need to reverse
   537 multiple declarations for same syntax element constant;
   538 
   539 * Pure/show_hyps reset by default (in accordance to existing Isar
   540 practice);
   541 
   542 * Provers/classical: renamed addaltern to addafter, addSaltern to
   543 addSafter;
   544 
   545 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   546 as well;
   547 
   548 * system: tested support for MacOS X; should be able to get Isabelle +
   549 Proof General to work in a plain Terminal after installing Poly/ML
   550 (e.g. from the Isabelle distribution area) and GNU bash alone
   551 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   552 support requires further installations, e.g. from
   553 http://fink.sourceforge.net/);
   554 
   555 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   556 
   557 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   558 of 40 MB), cf. ML_OPTIONS;
   559 
   560 * system: Proof General keywords specification is now part of the
   561 Isabelle distribution (see etc/isar-keywords.el);
   562 
   563 * system: support for persistent Proof General sessions (refrain from
   564 outdating all loaded theories on startup); user may create writable
   565 logic images like this: ``isabelle -q HOL Test'';
   566 
   567 * system: smart selection of Isabelle process versus Isabelle
   568 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   569 run both "isabelle" and "Isabelle" even if file names are badly
   570 damaged (executable inspects the case of the first letter of its own
   571 name); added separate "isabelle-process" and "isabelle-interface";
   572 
   573 * system: refrain from any attempt at filtering input streams; no
   574 longer support ``8bit'' encoding of old isabelle font, instead proper
   575 iso-latin characters may now be used; the related isatools
   576 "symbolinput" and "nonascii" have disappeared as well;
   577 
   578 * system: removed old "xterm" interface (the print modes "xterm" and
   579 "xterm_color" are still available for direct use in a suitable
   580 terminal);
   581 
   582 
   583 
   584 New in Isabelle99-2 (February 2001)
   585 -----------------------------------
   586 
   587 *** Overview of INCOMPATIBILITIES ***
   588 
   589 * HOL: please note that theories in the Library and elsewhere often use the
   590 new-style (Isar) format; to refer to their theorems in an ML script you must
   591 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   592 
   593 * HOL: inductive package no longer splits induction rule aggressively,
   594 but only as far as specified by the introductions given; the old
   595 format may be recovered via ML function complete_split_rule or attribute
   596 'split_rule (complete)';
   597 
   598 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   599 gfp_Tarski to gfp_unfold;
   600 
   601 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   602 
   603 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   604 relation); infix "^^" has been renamed "``"; infix "``" has been
   605 renamed "`"; "univalent" has been renamed "single_valued";
   606 
   607 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   608 operation;
   609 
   610 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   611 
   612 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   613 
   614 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   615 consequence, it is no longer monotonic wrt. the local goal context
   616 (which is now passed through the inductive cases);
   617 
   618 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   619 \<gg> to \<ggreater>;
   620 
   621 
   622 *** Document preparation ***
   623 
   624 * \isabellestyle{NAME} selects version of Isabelle output (currently
   625 available: are "it" for near math-mode best-style output, "sl" for
   626 slanted text style, and "tt" for plain type-writer; if no
   627 \isabellestyle command is given, output is according to slanted
   628 type-writer);
   629 
   630 * support sub/super scripts (for single symbols only), input syntax is
   631 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   632 
   633 * some more standard symbols; see Appendix A of the system manual for
   634 the complete list of symbols defined in isabellesym.sty;
   635 
   636 * improved isabelle style files; more abstract symbol implementation
   637 (should now use \isamath{...} and \isatext{...} in custom symbol
   638 definitions);
   639 
   640 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   641 state; Note that presentation of goal states does not conform to
   642 actual human-readable proof documents.  Please do not include goal
   643 states into document output unless you really know what you are doing!
   644 
   645 * proper indentation of antiquoted output with proportional LaTeX
   646 fonts;
   647 
   648 * no_document ML operator temporarily disables LaTeX document
   649 generation;
   650 
   651 * isatool unsymbolize tunes sources for plain ASCII communication;
   652 
   653 
   654 *** Isar ***
   655 
   656 * Pure: Isar now suffers initial goal statements to contain unbound
   657 schematic variables (this does not conform to actual readable proof
   658 documents, due to unpredictable outcome and non-compositional proof
   659 checking); users who know what they are doing may use schematic goals
   660 for Prolog-style synthesis of proven results;
   661 
   662 * Pure: assumption method (an implicit finishing) now handles actual
   663 rules as well;
   664 
   665 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   666 initial goal, declare "that" only as Pure intro (only for single
   667 steps); the "that" rule assumption may now be involved in implicit
   668 finishing, thus ".." becomes a feasible for trivial obtains;
   669 
   670 * Pure: default proof step now includes 'intro_classes'; thus trivial
   671 instance proofs may be performed by "..";
   672 
   673 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   674 statements as well;
   675 
   676 * Pure: more robust selection of calculational rules;
   677 
   678 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   679 rule (as well as the assumption rule);
   680 
   681 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   682 lemmas, using the graph browser tool;
   683 
   684 * Pure: predict failure of "show" in interactive mode;
   685 
   686 * Pure: 'thms_containing' now takes actual terms as arguments;
   687 
   688 * HOL: improved method 'induct' --- now handles non-atomic goals
   689 (potential INCOMPATIBILITY); tuned error handling;
   690 
   691 * HOL: cases and induct rules now provide explicit hints about the
   692 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   693 any remaining facts are inserted into the goal verbatim;
   694 
   695 * HOL: local contexts (aka cases) may now contain term bindings as
   696 well; the 'cases' and 'induct' methods new provide a ?case binding for
   697 the result to be shown in each case;
   698 
   699 * HOL: added 'recdef_tc' command;
   700 
   701 * isatool convert assists in eliminating legacy ML scripts;
   702 
   703 
   704 *** HOL ***
   705 
   706 * HOL/Library: a collection of generic theories to be used together
   707 with main HOL; the theory loader path already includes this directory
   708 by default; the following existing theories have been moved here:
   709 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   710 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   711 
   712 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   713 modelling and verification task performed in Isabelle/HOL +
   714 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   715 
   716 * HOL/Algebra: special summation operator SUM no longer exists, it has
   717 been replaced by setsum; infix 'assoc' now has priority 50 (like
   718 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   719 'domain', this makes the theory consistent with mathematical
   720 literature;
   721 
   722 * HOL basics: added overloaded operations "inverse" and "divide"
   723 (infix "/"), syntax for generic "abs" operation, generic summation
   724 operator \<Sum>;
   725 
   726 * HOL/typedef: simplified package, provide more useful rules (see also
   727 HOL/subset.thy);
   728 
   729 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   730 now expressed as a proper nested rule (old-style tactic scripts may
   731 require atomize_strip_tac to cope with non-atomic premises);
   732 
   733 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   734 to "split_conv" (old name still available for compatibility);
   735 
   736 * HOL: improved concrete syntax for strings (e.g. allows translation
   737 rules with string literals);
   738 
   739 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   740  and Fleuriot's mechanization of analysis, including the transcendental
   741  functions for the reals;
   742 
   743 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   744 
   745 
   746 *** CTT ***
   747 
   748 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   749 "lam" is displayed as TWO lambda-symbols
   750 
   751 * CTT: theory Main now available, containing everything (that is, Bool
   752 and Arith);
   753 
   754 
   755 *** General ***
   756 
   757 * Pure: the Simplifier has been implemented properly as a derived rule
   758 outside of the actual kernel (at last!); the overall performance
   759 penalty in practical applications is about 50%, while reliability of
   760 the Isabelle inference kernel has been greatly improved;
   761 
   762 * print modes "brackets" and "no_brackets" control output of nested =>
   763 (types) and ==> (props); the default behaviour is "brackets";
   764 
   765 * Provers: fast_tac (and friends) now handle actual object-logic rules
   766 as assumptions as well;
   767 
   768 * system: support Poly/ML 4.0;
   769 
   770 * system: isatool install handles KDE version 1 or 2;
   771 
   772 
   773 
   774 New in Isabelle99-1 (October 2000)
   775 ----------------------------------
   776 
   777 *** Overview of INCOMPATIBILITIES ***
   778 
   779 * HOL: simplification of natural numbers is much changed; to partly
   780 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   781 issue the following ML commands:
   782 
   783   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   784   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   785 
   786 * HOL: simplification no longer dives into case-expressions; this is
   787 controlled by "t.weak_case_cong" for each datatype t;
   788 
   789 * HOL: nat_less_induct renamed to less_induct;
   790 
   791 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   792 fixsome to patch .thy and .ML sources automatically;
   793 
   794   select_equality  -> some_equality
   795   select_eq_Ex     -> some_eq_ex
   796   selectI2EX       -> someI2_ex
   797   selectI2         -> someI2
   798   selectI          -> someI
   799   select1_equality -> some1_equality
   800   Eps_sym_eq       -> some_sym_eq_trivial
   801   Eps_eq           -> some_eq_trivial
   802 
   803 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   804 
   805 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   806 instead);
   807 
   808 * HOL: the recursion equations generated by 'recdef' are now called
   809 f.simps instead of f.rules;
   810 
   811 * HOL: qed_spec_mp now also handles bounded ALL as well;
   812 
   813 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   814 sometimes be needed;
   815 
   816 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   817 
   818 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   819 
   820 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   821 product is now "<*>" instead of "Times"; the lexicographic product is
   822 now "<*lex*>" instead of "**";
   823 
   824 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   825 of main HOL, but was unused); better use HOL's datatype package;
   826 
   827 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   828 the old syntax may be recovered as follows:
   829 
   830   syntax (symbols)
   831     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   832       (infixl "\\<oplus>" 100)
   833 
   834 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   835 
   836 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   837 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   838 internally;
   839 
   840 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   841 changed from A/r to A//r;
   842 
   843 * ZF: new treatment of arithmetic (nat & int) may break some old
   844 proofs;
   845 
   846 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   847 rulify -> rule_format, elimify -> elim_format, ...);
   848 
   849 * Isar/Provers: intro/elim/dest attributes changed; renamed
   850 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   851 should have to change intro!! to intro? only); replaced "delrule" by
   852 "rule del";
   853 
   854 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   855 
   856 * Provers: strengthened force_tac by using new first_best_tac;
   857 
   858 * LaTeX document preparation: several changes of isabelle.sty (see
   859 lib/texinputs);
   860 
   861 
   862 *** Document preparation ***
   863 
   864 * formal comments (text blocks etc.) in new-style theories may now
   865 contain antiquotations of thm/prop/term/typ/text to be presented
   866 according to latex print mode; concrete syntax is like this:
   867 @{term[show_types] "f(x) = a + x"};
   868 
   869 * isatool mkdir provides easy setup of Isabelle session directories,
   870 including proper document sources;
   871 
   872 * generated LaTeX sources are now deleted after successful run
   873 (isatool document -c); may retain a copy somewhere else via -D option
   874 of isatool usedir;
   875 
   876 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   877 style files, achieving self-contained LaTeX sources and simplifying
   878 LaTeX debugging;
   879 
   880 * old-style theories now produce (crude) LaTeX output as well;
   881 
   882 * browser info session directories are now self-contained (may be put
   883 on WWW server seperately); improved graphs of nested sessions; removed
   884 graph for 'all sessions';
   885 
   886 * several improvements in isabelle style files; \isabellestyle{it}
   887 produces fake math mode output; \isamarkupheader is now \section by
   888 default; see lib/texinputs/isabelle.sty etc.;
   889 
   890 
   891 *** Isar ***
   892 
   893 * Isar/Pure: local results and corresponding term bindings are now
   894 subject to Hindley-Milner polymorphism (similar to ML); this
   895 accommodates incremental type-inference very nicely;
   896 
   897 * Isar/Pure: new derived language element 'obtain' supports
   898 generalized existence reasoning;
   899 
   900 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   901 support accumulation of results, without applying any rules yet;
   902 useful to collect intermediate results without explicit name
   903 references, and for use with transitivity rules with more than 2
   904 premises;
   905 
   906 * Isar/Pure: scalable support for case-analysis type proofs: new
   907 'case' language element refers to local contexts symbolically, as
   908 produced by certain proof methods; internally, case names are attached
   909 to theorems as "tags";
   910 
   911 * Isar/Pure: theory command 'hide' removes declarations from
   912 class/type/const name spaces;
   913 
   914 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   915 indicate potential overloading;
   916 
   917 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   918 
   919 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   920 "{a,b,c}" instead of {a,b,c};
   921 
   922 * Isar/Pure now provides its own version of intro/elim/dest
   923 attributes; useful for building new logics, but beware of confusion
   924 with the version in Provers/classical;
   925 
   926 * Isar/Pure: the local context of (non-atomic) goals is provided via
   927 case name 'antecedent';
   928 
   929 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   930 to the current context is now done automatically);
   931 
   932 * Isar/Pure: theory command 'method_setup' provides a simple interface
   933 for definining proof methods in ML;
   934 
   935 * Isar/Provers: intro/elim/dest attributes changed; renamed
   936 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   937 most cases, one should have to change intro!! to intro? only);
   938 replaced "delrule" by "rule del";
   939 
   940 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   941 'symmetric' attribute (the latter supercedes [RS sym]);
   942 
   943 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   944 method modifier); 'simp' method: 'only:' modifier removes loopers as
   945 well (including splits);
   946 
   947 * Isar/Provers: Simplifier and Classical methods now support all kind
   948 of modifiers used in the past, including 'cong', 'iff', etc.
   949 
   950 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   951 of Simplifier and Classical reasoner);
   952 
   953 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   954 now support named cases; major packages (inductive, datatype, primrec,
   955 recdef) support case names and properly name parameters;
   956 
   957 * Isar/HOL: new transitivity rules for substitution in inequalities --
   958 monotonicity conditions are extracted to be proven at end of
   959 calculations;
   960 
   961 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   962 method anyway;
   963 
   964 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   965 split_if split_if_asm; datatype package provides theorems foo.splits =
   966 foo.split foo.split_asm for each datatype;
   967 
   968 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   969 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   970 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   971 use "(cases (simplified))" method in proper proof texts);
   972 
   973 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   974 
   975 * Isar: names of theorems etc. may be natural numbers as well;
   976 
   977 * Isar: 'pr' command: optional arguments for goals_limit and
   978 ProofContext.prems_limit; no longer prints theory contexts, but only
   979 proof states;
   980 
   981 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   982 additional print modes to be specified; e.g. "pr(latex)" will print
   983 proof state according to the Isabelle LaTeX style;
   984 
   985 * Isar: improved support for emulating tactic scripts, including proof
   986 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   987 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   988 (for HOL datatypes);
   989 
   990 * Isar: simplified (more robust) goal selection of proof methods: 1st
   991 goal, all goals, or explicit goal specifier (tactic emulation); thus
   992 'proof method scripts' have to be in depth-first order;
   993 
   994 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   995 
   996 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   997 should instead use individual commands for printing items
   998 (print_commands, print_methods etc.);
   999 
  1000 * Isar: added 'nothing' --- the empty list of theorems;
  1001 
  1002 
  1003 *** HOL ***
  1004 
  1005 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1006 corresponding virtual machine and a specification of its bytecode
  1007 verifier and a lightweight bytecode verifier, including proofs of
  1008 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1009 Cornelia Pusch (see also the homepage of project Bali at
  1010 http://isabelle.in.tum.de/Bali/);
  1011 
  1012 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1013 Clemens Ballarin;
  1014 
  1015 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1016 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1017 Rasmussen;
  1018 
  1019 * HOL/Lattice: fundamental concepts of lattice theory and order
  1020 structures, including duals, properties of bounds versus algebraic
  1021 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1022 Theorem for complete lattices etc.; may also serve as a demonstration
  1023 for abstract algebraic reasoning using axiomatic type classes, and
  1024 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1025 
  1026 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1027 von Oheimb;
  1028 
  1029 * HOL/IMPP: extension of IMP with local variables and mutually
  1030 recursive procedures, by David von Oheimb;
  1031 
  1032 * HOL/Lambda: converted into new-style theory and document;
  1033 
  1034 * HOL/ex/Multiquote: example of multiple nested quotations and
  1035 anti-quotations -- basically a generalized version of de-Bruijn
  1036 representation; very useful in avoiding lifting of operations;
  1037 
  1038 * HOL/record: added general record equality rule to simpset; fixed
  1039 select-update simplification procedure to handle extended records as
  1040 well; admit "r" as field name;
  1041 
  1042 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1043 other numeric types and also as the identity of groups, rings, etc.;
  1044 
  1045 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1046 Types nat and int belong to this axclass;
  1047 
  1048 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1049    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1050    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1051   two terms #m*u and #n*u are replaced by #(m+n)*u
  1052     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1053   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1054     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1055 
  1056 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1057 powerful prover for predicate logic but knows nothing of clasets; see
  1058 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1059 
  1060 * HOL: new version of "case_tac" subsumes both boolean case split and
  1061 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1062 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1063 
  1064 * HOL: simplification no longer dives into case-expressions: only the
  1065 selector expression is simplified, but not the remaining arms; to
  1066 enable full simplification of case-expressions for datatype t, you may
  1067 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1068 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1069 
  1070 * HOL/recdef: the recursion equations generated by 'recdef' for
  1071 function 'f' are now called f.simps instead of f.rules; if all
  1072 termination conditions are proved automatically, these simplification
  1073 rules are added to the simpset, as in primrec; rules may be named
  1074 individually as well, resulting in a separate list of theorems for
  1075 each equation;
  1076 
  1077 * HOL/While is a new theory that provides a while-combinator. It
  1078 permits the definition of tail-recursive functions without the
  1079 provision of a termination measure. The latter is necessary once the
  1080 invariant proof rule for while is applied.
  1081 
  1082 * HOL: new (overloaded) notation for the set of elements below/above
  1083 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1084 
  1085 * HOL: theorems impI, allI, ballI bound as "strip";
  1086 
  1087 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1088 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1089 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1090 
  1091 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1092 
  1093 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1094 main HOL, but was unused);
  1095 
  1096 * HOL: fewer consts declared as global (e.g. have to refer to
  1097 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1098 
  1099 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1100 in case of overlap with user translations (e.g. judgements over
  1101 tuples); (note that the underlying logical represenation is still
  1102 bogus);
  1103 
  1104 
  1105 *** ZF ***
  1106 
  1107 * ZF: simplification automatically cancels common terms in arithmetic
  1108 expressions over nat and int;
  1109 
  1110 * ZF: new treatment of nat to minimize type-checking: all operators
  1111 coerce their operands to a natural number using the function natify,
  1112 making the algebraic laws unconditional;
  1113 
  1114 * ZF: as above, for int: operators coerce their operands to an integer
  1115 using the function intify;
  1116 
  1117 * ZF: the integer library now contains many of the usual laws for the
  1118 orderings, including $<=, and monotonicity laws for $+ and $*;
  1119 
  1120 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1121 simplification;
  1122 
  1123 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1124 to the simplifier and classical reasoner simultaneously;
  1125 
  1126 
  1127 *** General ***
  1128 
  1129 * Provers: blast_tac now handles actual object-logic rules as
  1130 assumptions; note that auto_tac uses blast_tac internally as well;
  1131 
  1132 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1133 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1134 
  1135 * Provers: delrules now handles destruct rules as well (no longer need
  1136 explicit make_elim);
  1137 
  1138 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1139   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1140 use instead the strong form,
  1141   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1142 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1143 from destruct-rules;
  1144 
  1145 * Provers: Simplifier.easy_setup provides a fast path to basic
  1146 Simplifier setup for new object-logics;
  1147 
  1148 * Pure: AST translation rules no longer require constant head on LHS;
  1149 
  1150 * Pure: improved name spaces: ambiguous output is qualified; support
  1151 for hiding of names;
  1152 
  1153 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1154 XSYMBOL_HOME; no longer need to do manual configuration in most
  1155 situations;
  1156 
  1157 * system: compression of ML heaps images may now be controlled via -c
  1158 option of isabelle and isatool usedir (currently only observed by
  1159 Poly/ML);
  1160 
  1161 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1162 useful for remote X11);
  1163 
  1164 * system: provide TAGS file for Isabelle sources;
  1165 
  1166 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1167 order;
  1168 
  1169 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1170 timing flag supersedes proof_timing and Toplevel.trace;
  1171 
  1172 * ML: new combinators |>> and |>>> for incremental transformations
  1173 with secondary results (e.g. certain theory extensions):
  1174 
  1175 * ML: PureThy.add_defs gets additional argument to indicate potential
  1176 overloading (usually false);
  1177 
  1178 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1179 results;
  1180 
  1181 
  1182 
  1183 New in Isabelle99 (October 1999)
  1184 --------------------------------
  1185 
  1186 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1187 
  1188 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1189 are no longer simplified.  (This allows the simplifier to unfold recursive
  1190 functional programs.)  To restore the old behaviour, declare
  1191 
  1192     Delcongs [if_weak_cong];
  1193 
  1194 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1195 complement;
  1196 
  1197 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1198 
  1199 * HOL/datatype: mutual_induct_tac no longer exists --
  1200   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1201 
  1202 * HOL/typedef: fixed type inference for representing set; type
  1203 arguments now have to occur explicitly on the rhs as type constraints;
  1204 
  1205 * ZF: The con_defs part of an inductive definition may no longer refer
  1206 to constants declared in the same theory;
  1207 
  1208 * HOL, ZF: the function mk_cases, generated by the inductive
  1209 definition package, has lost an argument.  To simplify its result, it
  1210 uses the default simpset instead of a supplied list of theorems.
  1211 
  1212 * HOL/List: the constructors of type list are now Nil and Cons;
  1213 
  1214 * Simplifier: the type of the infix ML functions
  1215         setSSolver addSSolver setSolver addSolver
  1216 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1217 for packaging solvers. A solver is created via
  1218         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1219 where the string argument is only a comment.
  1220 
  1221 
  1222 *** Proof tools ***
  1223 
  1224 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1225 decision procedure for linear arithmetic. Currently it is used for
  1226 types `nat', `int', and `real' in HOL (see below); it can, should and
  1227 will be instantiated for other types and logics as well.
  1228 
  1229 * The simplifier now accepts rewrite rules with flexible heads, eg
  1230      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1231   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1232   matching.
  1233 
  1234 
  1235 *** General ***
  1236 
  1237 * New Isabelle/Isar subsystem provides an alternative to traditional
  1238 tactical theorem proving; together with the ProofGeneral/isar user
  1239 interface it offers an interactive environment for developing human
  1240 readable proof documents (Isar == Intelligible semi-automated
  1241 reasoning); for further information see isatool doc isar-ref,
  1242 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1243 
  1244 * improved and simplified presentation of theories: better HTML markup
  1245 (including colors), graph views in several sizes; isatool usedir now
  1246 provides a proper interface for user theories (via -P option); actual
  1247 document preparation based on (PDF)LaTeX is available as well (for
  1248 new-style theories only); see isatool doc system for more information;
  1249 
  1250 * native support for Proof General, both for classic Isabelle and
  1251 Isabelle/Isar;
  1252 
  1253 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1254 using the graph browser tool;
  1255 
  1256 * Isabelle manuals now also available as PDF;
  1257 
  1258 * theory loader rewritten from scratch (may not be fully
  1259 bug-compatible); old loadpath variable has been replaced by show_path,
  1260 add_path, del_path, reset_path functions; new operations such as
  1261 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1262 isatool doc ref);
  1263 
  1264 * improved isatool install: option -k creates KDE application icon,
  1265 option -p DIR installs standalone binaries;
  1266 
  1267 * added ML_PLATFORM setting (useful for cross-platform installations);
  1268 more robust handling of platform specific ML images for SML/NJ;
  1269 
  1270 * the settings environment is now statically scoped, i.e. it is never
  1271 created again in sub-processes invoked from isabelle, isatool, or
  1272 Isabelle;
  1273 
  1274 * path element specification '~~' refers to '$ISABELLE_HOME';
  1275 
  1276 * in locales, the "assumes" and "defines" parts may be omitted if
  1277 empty;
  1278 
  1279 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1280 long arrows);
  1281 
  1282 * new print_mode "HTML";
  1283 
  1284 * new flag show_tags controls display of tags of theorems (which are
  1285 basically just comments that may be attached by some tools);
  1286 
  1287 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1288 mode and goal output format:
  1289 
  1290 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1291 244c244
  1292 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1293 ---
  1294 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1295 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1296 181c181
  1297 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1298 ---
  1299 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1300 
  1301 * function bind_thms stores lists of theorems (cf. bind_thm);
  1302 
  1303 * new shorthand tactics ftac, eatac, datac, fatac;
  1304 
  1305 * qed (and friends) now accept "" as result name; in that case the
  1306 theorem is not stored, but proper checks and presentation of the
  1307 result still apply;
  1308 
  1309 * theorem database now also indexes constants "Trueprop", "all",
  1310 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1311 
  1312 
  1313 *** HOL ***
  1314 
  1315 ** HOL arithmetic **
  1316 
  1317 * There are now decision procedures for linear arithmetic over nat and
  1318 int:
  1319 
  1320 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1321 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1322 are treated as atomic; subformulae not involving type `nat' or `int'
  1323 are ignored; quantified subformulae are ignored unless they are
  1324 positive universal or negative existential. The tactic has to be
  1325 invoked by hand and can be a little bit slow. In particular, the
  1326 running time is exponential in the number of occurrences of `min' and
  1327 `max', and `-' on `nat'.
  1328 
  1329 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1330 (negated) (in)equalities among the premises and the conclusion into
  1331 account (i.e. no compound formulae) and does not know about `min' and
  1332 `max', and `-' on `nat'. It is fast and is used automatically by the
  1333 simplifier.
  1334 
  1335 NB: At the moment, these decision procedures do not cope with mixed
  1336 nat/int formulae where the two parts interact, such as `m < n ==>
  1337 int(m) < int(n)'.
  1338 
  1339 * HOL/Numeral provides a generic theory of numerals (encoded
  1340 efficiently as bit strings); setup for types nat/int/real is in place;
  1341 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1342 int, existing theories and proof scripts may require a few additional
  1343 type constraints;
  1344 
  1345 * integer division and remainder can now be performed on constant
  1346 arguments;
  1347 
  1348 * many properties of integer multiplication, division and remainder
  1349 are now available;
  1350 
  1351 * An interface to the Stanford Validity Checker (SVC) is available through the
  1352 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1353 are proved automatically.  SVC must be installed separately, and its results
  1354 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1355 invocation of the underlying oracle).  For SVC see
  1356   http://verify.stanford.edu/SVC
  1357 
  1358 * IsaMakefile: the HOL-Real target now builds an actual image;
  1359 
  1360 
  1361 ** HOL misc **
  1362 
  1363 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1364 (in Isabelle/Isar) -- by Gertrud Bauer;
  1365 
  1366 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1367 analysis for assembly languages with subtypes;
  1368 
  1369 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1370 -- avoids syntactic ambiguities and treats state, transition, and
  1371 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1372 changed syntax and (many) tactics;
  1373 
  1374 * HOL/inductive: Now also handles more general introduction rules such
  1375   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1376   theorems are now maintained within the theory (maintained via the
  1377   "mono" attribute);
  1378 
  1379 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1380   (using function types) such as
  1381 
  1382   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1383 
  1384 * HOL/record: record_simproc (part of the default simpset) takes care
  1385 of selectors applied to updated records; record_split_tac is no longer
  1386 part of the default claset; update_defs may now be removed from the
  1387 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1388 
  1389   claset_ref () := claset() addSWrapper record_split_wrapper;
  1390   Delsimprocs [record_simproc]
  1391 
  1392 * HOL/typedef: fixed type inference for representing set; type
  1393 arguments now have to occur explicitly on the rhs as type constraints;
  1394 
  1395 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1396 names rather than an ML expression;
  1397 
  1398 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1399 supplied later.  Program schemes can be defined, such as
  1400     "While B C s = (if B s then While B C (C s) else s)"
  1401 where the well-founded relation can be chosen after B and C have been given.
  1402 
  1403 * HOL/List: the constructors of type list are now Nil and Cons;
  1404 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1405 course, ML tools referring to List.list.op # etc. have to be adapted;
  1406 
  1407 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1408 disabled by default; run isabelle with option -m HOL to get back to
  1409 the original Gordon/HOL-style output;
  1410 
  1411 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1412 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1413 
  1414 * HOL basic syntax simplified (more orthogonal): all variants of
  1415 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1416 Eps operator is provided as well: "SOME x. P[x]";
  1417 
  1418 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1419 
  1420 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1421 thus available for user theories;
  1422 
  1423 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1424 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1425 time;
  1426 
  1427 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1428 several times and then mp;
  1429 
  1430 
  1431 *** LK ***
  1432 
  1433 * the notation <<...>> is now available as a notation for sequences of
  1434 formulas;
  1435 
  1436 * the simplifier is now installed
  1437 
  1438 * the axiom system has been generalized (thanks to Soren Heilmann)
  1439 
  1440 * the classical reasoner now has a default rule database
  1441 
  1442 
  1443 *** ZF ***
  1444 
  1445 * new primrec section allows primitive recursive functions to be given
  1446 directly (as in HOL) over datatypes and the natural numbers;
  1447 
  1448 * new tactics induct_tac and exhaust_tac for induction (or case
  1449 analysis) over datatypes and the natural numbers;
  1450 
  1451 * the datatype declaration of type T now defines the recursor T_rec;
  1452 
  1453 * simplification automatically does freeness reasoning for datatype
  1454 constructors;
  1455 
  1456 * automatic type-inference, with AddTCs command to insert new
  1457 type-checking rules;
  1458 
  1459 * datatype introduction rules are now added as Safe Introduction rules
  1460 to the claset;
  1461 
  1462 * the syntax "if P then x else y" is now available in addition to
  1463 if(P,x,y);
  1464 
  1465 
  1466 *** Internal programming interfaces ***
  1467 
  1468 * tuned simplifier trace output; new flag debug_simp;
  1469 
  1470 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1471 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1472 
  1473 * AxClass.axclass_tac lost the theory argument;
  1474 
  1475 * tuned current_goals_markers semantics: begin / end goal avoids
  1476 printing empty lines;
  1477 
  1478 * removed prs and prs_fn hook, which was broken because it did not
  1479 include \n in its semantics, forcing writeln to add one
  1480 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1481 string -> unit if you really want to output text without newline;
  1482 
  1483 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1484 plain output, interface builders may have to enable 'isabelle_font'
  1485 mode to get Isabelle font glyphs as before;
  1486 
  1487 * refined token_translation interface; INCOMPATIBILITY: output length
  1488 now of type real instead of int;
  1489 
  1490 * theory loader actions may be traced via new ThyInfo.add_hook
  1491 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1492 your own database of information attached to *whole* theories -- as
  1493 opposed to intra-theory data slots offered via TheoryDataFun;
  1494 
  1495 * proper handling of dangling sort hypotheses (at last!);
  1496 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1497 extra sort hypotheses that can be witnessed from the type signature;
  1498 the force_strip_shyps flag is gone, any remaining shyps are simply
  1499 left in the theorem (with a warning issued by strip_shyps_warning);
  1500 
  1501 
  1502 
  1503 New in Isabelle98-1 (October 1998)
  1504 ----------------------------------
  1505 
  1506 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1507 
  1508 * several changes of automated proof tools;
  1509 
  1510 * HOL: major changes to the inductive and datatype packages, including
  1511 some minor incompatibilities of theory syntax;
  1512 
  1513 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1514 called `inj_on';
  1515 
  1516 * HOL: removed duplicate thms in Arith:
  1517   less_imp_add_less  should be replaced by  trans_less_add1
  1518   le_imp_add_le      should be replaced by  trans_le_add1
  1519 
  1520 * HOL: unary minus is now overloaded (new type constraints may be
  1521 required);
  1522 
  1523 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1524 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1525 now taken as an integer constant.
  1526 
  1527 * Pure: ML function 'theory_of' renamed to 'theory';
  1528 
  1529 
  1530 *** Proof tools ***
  1531 
  1532 * Simplifier:
  1533   1. Asm_full_simp_tac is now more aggressive.
  1534      1. It will sometimes reorient premises if that increases their power to
  1535         simplify.
  1536      2. It does no longer proceed strictly from left to right but may also
  1537         rotate premises to achieve further simplification.
  1538      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1539      old Asm_full_simp_tac in that it does not rotate premises.
  1540   2. The simplifier now knows a little bit about nat-arithmetic.
  1541 
  1542 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1543 allows for selected deletion of wrappers, by introduction of names for
  1544 wrapper functionals.  This implies that addbefore, addSbefore,
  1545 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1546 and that adding two tactics with the same name overwrites the first
  1547 one (emitting a warning).
  1548   type wrapper = (int -> tactic) -> (int -> tactic)
  1549   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1550   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1551   delWrapper, delSWrapper: claset *  string            -> claset
  1552   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1553 
  1554 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1555 semantics; addbefore now affects only the unsafe part of step_tac
  1556 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1557 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1558 by Force_tac;
  1559 
  1560 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1561 compWrapper; added safe wrapper (and access functions for it);
  1562 
  1563 * HOL/split_all_tac is now much faster and fails if there is nothing
  1564 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1565 and the names of the automatically generated variables have changed.
  1566 split_all_tac has moved within claset() from unsafe wrappers to safe
  1567 wrappers, which means that !!-bound variables are split much more
  1568 aggressively, and safe_tac and clarify_tac now split such variables.
  1569 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1570 Note: the same holds for record_split_tac, which does the job of
  1571 split_all_tac for record fields.
  1572 
  1573 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1574 permanently to the default simpset using Addsplits just like
  1575 Addsimps. They can be removed via Delsplits just like
  1576 Delsimps. Lower-case versions are also available.
  1577 
  1578 * HOL/Simplifier: The rule split_if is now part of the default
  1579 simpset. This means that the simplifier will eliminate all occurrences
  1580 of if-then-else in the conclusion of a goal. To prevent this, you can
  1581 either remove split_if completely from the default simpset by
  1582 `Delsplits [split_if]' or remove it in a specific call of the
  1583 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1584 other case splitting rules to/from the default simpset: every datatype
  1585 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1586 t is the name of the datatype).
  1587 
  1588 * Classical reasoner / Simplifier combination: new force_tac (and
  1589 derivatives Force_tac, force) combines rewriting and classical
  1590 reasoning (and whatever other tools) similarly to auto_tac, but is
  1591 aimed to solve the given subgoal completely.
  1592 
  1593 
  1594 *** General ***
  1595 
  1596 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1597 and `goalw': the theory is no longer needed as an explicit argument -
  1598 the current theory context is used; assumptions are no longer returned
  1599 at the ML-level unless one of them starts with ==> or !!; it is
  1600 recommended to convert to these new commands using isatool fixgoal
  1601 (backup your sources first!);
  1602 
  1603 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1604 the current theory context, and 'theory' to lookup stored theories;
  1605 
  1606 * new theory section 'locale' for declaring constants, assumptions and
  1607 definitions that have local scope;
  1608 
  1609 * new theory section 'nonterminals' for purely syntactic types;
  1610 
  1611 * new theory section 'setup' for generic ML setup functions
  1612 (e.g. package initialization);
  1613 
  1614 * the distribution now includes Isabelle icons: see
  1615 lib/logo/isabelle-{small,tiny}.xpm;
  1616 
  1617 * isatool install - install binaries with absolute references to
  1618 ISABELLE_HOME/bin;
  1619 
  1620 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1621 
  1622 * print mode 'emacs' reserved for Isamode;
  1623 
  1624 * support multiple print (ast) translations per constant name;
  1625 
  1626 * theorems involving oracles are now printed with a suffixed [!];
  1627 
  1628 
  1629 *** HOL ***
  1630 
  1631 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1632 
  1633 * HOL/inductive package reorganized and improved: now supports mutual
  1634 definitions such as
  1635 
  1636   inductive EVEN ODD
  1637     intrs
  1638       null "0 : EVEN"
  1639       oddI "n : EVEN ==> Suc n : ODD"
  1640       evenI "n : ODD ==> Suc n : EVEN"
  1641 
  1642 new theorem list "elims" contains an elimination rule for each of the
  1643 recursive sets; inductive definitions now handle disjunctive premises
  1644 correctly (also ZF);
  1645 
  1646 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1647 "mutual_induct" no longer exists - the induction rule is always
  1648 contained in "induct";
  1649 
  1650 
  1651 * HOL/datatype package re-implemented and greatly improved: now
  1652 supports mutually recursive datatypes such as
  1653 
  1654   datatype
  1655     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1656             | SUM ('a aexp) ('a aexp)
  1657             | DIFF ('a aexp) ('a aexp)
  1658             | NUM 'a
  1659   and
  1660     'a bexp = LESS ('a aexp) ('a aexp)
  1661             | AND ('a bexp) ('a bexp)
  1662             | OR ('a bexp) ('a bexp)
  1663 
  1664 as well as indirectly recursive datatypes such as
  1665 
  1666   datatype
  1667     ('a, 'b) term = Var 'a
  1668                   | App 'b ((('a, 'b) term) list)
  1669 
  1670 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1671 induction on mutually / indirectly recursive datatypes.
  1672 
  1673 Primrec equations are now stored in theory and can be accessed via
  1674 <function_name>.simps.
  1675 
  1676 INCOMPATIBILITIES:
  1677 
  1678   - Theories using datatypes must now have theory Datatype as an
  1679     ancestor.
  1680   - The specific <typename>.induct_tac no longer exists - use the
  1681     generic induct_tac instead.
  1682   - natE has been renamed to nat.exhaust - use exhaust_tac
  1683     instead of res_inst_tac ... natE. Note that the variable
  1684     names in nat.exhaust differ from the names in natE, this
  1685     may cause some "fragile" proofs to fail.
  1686   - The theorems split_<typename>_case and split_<typename>_case_asm
  1687     have been renamed to <typename>.split and <typename>.split_asm.
  1688   - Since default sorts of type variables are now handled correctly,
  1689     some datatype definitions may have to be annotated with explicit
  1690     sort constraints.
  1691   - Primrec definitions no longer require function name and type
  1692     of recursive argument.
  1693 
  1694 Consider using isatool fixdatatype to adapt your theories and proof
  1695 scripts to the new package (backup your sources first!).
  1696 
  1697 
  1698 * HOL/record package: considerably improved implementation; now
  1699 includes concrete syntax for record types, terms, updates; theorems
  1700 for surjective pairing and splitting !!-bound record variables; proof
  1701 support is as follows:
  1702 
  1703   1) standard conversions (selectors or updates applied to record
  1704 constructor terms) are part of the standard simpset;
  1705 
  1706   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1707 made part of standard simpset and claset via addIffs;
  1708 
  1709   3) a tactic for record field splitting (record_split_tac) is part of
  1710 the standard claset (addSWrapper);
  1711 
  1712 To get a better idea about these rules you may retrieve them via
  1713 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1714 the name of your record type.
  1715 
  1716 The split tactic 3) conceptually simplifies by the following rule:
  1717 
  1718   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1719 
  1720 Thus any record variable that is bound by meta-all will automatically
  1721 blow up into some record constructor term, consequently the
  1722 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1723 solve record problems automatically.
  1724 
  1725 
  1726 * reorganized the main HOL image: HOL/Integ and String loaded by
  1727 default; theory Main includes everything;
  1728 
  1729 * automatic simplification of integer sums and comparisons, using cancellation;
  1730 
  1731 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1732 
  1733 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1734 
  1735 * many new identities for unions, intersections, set difference, etc.;
  1736 
  1737 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1738 called split_if, split_split, split_sum_case and split_nat_case (to go
  1739 with add/delsplits);
  1740 
  1741 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1742 (?x::unit) = (); this is made part of the default simpset, which COULD
  1743 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1744 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1745 unit_abs_eta_conv is added in order to counter the effect of
  1746 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1747 %u.f();
  1748 
  1749 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1750 makes more sense);
  1751 
  1752 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1753   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1754   disjointness reasoning but breaking a few old proofs.
  1755 
  1756 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1757 to 'converse' from 'inverse' (for compatibility with ZF and some
  1758 literature);
  1759 
  1760 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1761 the well-founded relation;
  1762 
  1763 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1764     Compl A.  The "Compl" syntax remains available as input syntax for this
  1765     release ONLY.
  1766 
  1767 * HOL/Update: new theory of function updates:
  1768     f(a:=b) == %x. if x=a then b else f x
  1769 may also be iterated as in f(a:=b,c:=d,...);
  1770 
  1771 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1772 
  1773 * HOL/List:
  1774   - new function list_update written xs[i:=v] that updates the i-th
  1775     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1776   - new function `upt' written [i..j(] which generates the list
  1777     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1778     bound write [i..j], which is a shorthand for [i..j+1(].
  1779   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1780 
  1781 * HOL/Arith:
  1782   - removed 'pred' (predecessor) function;
  1783   - generalized some theorems about n-1;
  1784   - many new laws about "div" and "mod";
  1785   - new laws about greatest common divisors (see theory ex/Primes);
  1786 
  1787 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1788 instead of "inverse";
  1789 
  1790 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1791   of the multiset ordering;
  1792 
  1793 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1794   (not included by default);
  1795 
  1796 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1797 
  1798 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1799   programs, i.e. different program variables may have different types.
  1800 
  1801 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1802   [previously, this check worked only if the rewrite rule was unconditional]
  1803   Now rew can involve either definitions or equalities (either == or =).
  1804 
  1805 
  1806 *** ZF ***
  1807 
  1808 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1809   only the theorems proved on ZF.ML;
  1810 
  1811 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1812   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1813   disjointness reasoning but breaking a few old proofs.
  1814 
  1815 * ZF/Update: new theory of function updates
  1816     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1817   may also be iterated as in f(a:=b,c:=d,...);
  1818 
  1819 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1820 
  1821 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1822   [previously, this check worked only if the rewrite rule was unconditional]
  1823   Now rew can involve either definitions or equalities (either == or =).
  1824 
  1825 * case_tac provided for compatibility with HOL
  1826     (like the old excluded_middle_tac, but with subgoals swapped)
  1827 
  1828 
  1829 *** Internal programming interfaces ***
  1830 
  1831 * Pure: several new basic modules made available for general use, see
  1832 also src/Pure/README;
  1833 
  1834 * improved the theory data mechanism to support encapsulation (data
  1835 kind name replaced by private Object.kind, acting as authorization
  1836 key); new type-safe user interface via functor TheoryDataFun; generic
  1837 print_data function becomes basically useless;
  1838 
  1839 * removed global_names compatibility flag -- all theory declarations
  1840 are qualified by default;
  1841 
  1842 * module Pure/Syntax now offers quote / antiquote translation
  1843 functions (useful for Hoare logic etc. with implicit dependencies);
  1844 see HOL/ex/Antiquote for an example use;
  1845 
  1846 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1847 cterm -> thm;
  1848 
  1849 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1850 subgoal;
  1851 
  1852 * Display.print_goals function moved to Locale.print_goals;
  1853 
  1854 * standard print function for goals supports current_goals_markers
  1855 variable for marking begin of proof, end of proof, start of goal; the
  1856 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1857 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1858 for example;
  1859 
  1860 
  1861 
  1862 New in Isabelle98 (January 1998)
  1863 --------------------------------
  1864 
  1865 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1866 
  1867 * changed lexical syntax of terms / types: dots made part of long
  1868 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1869 
  1870 * simpset (and claset) reference variable replaced by functions
  1871 simpset / simpset_ref;
  1872 
  1873 * no longer supports theory aliases (via merge) and non-trivial
  1874 implicit merge of thms' signatures;
  1875 
  1876 * most internal names of constants changed due to qualified names;
  1877 
  1878 * changed Pure/Sequence interface (see Pure/seq.ML);
  1879 
  1880 
  1881 *** General Changes ***
  1882 
  1883 * hierachically structured name spaces (for consts, types, axms, thms
  1884 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1885 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1886 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1887 long_names for fully qualified output names; NOTE: ML programs
  1888 (special tactics, packages etc.) referring to internal names may have
  1889 to be adapted to cope with fully qualified names; in case of severe
  1890 backward campatibility problems try setting 'global_names' at compile
  1891 time to have enrything declared within a flat name space; one may also
  1892 fine tune name declarations in theories via the 'global' and 'local'
  1893 section;
  1894 
  1895 * reimplemented the implicit simpset and claset using the new anytype
  1896 data filed in signatures; references simpset:simpset ref etc. are
  1897 replaced by functions simpset:unit->simpset and
  1898 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1899 to patch your ML files accordingly;
  1900 
  1901 * HTML output now includes theory graph data for display with Java
  1902 applet or isatool browser; data generated automatically via isatool
  1903 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1904 
  1905 * defs may now be conditional; improved rewrite_goals_tac to handle
  1906 conditional equations;
  1907 
  1908 * defs now admits additional type arguments, using TYPE('a) syntax;
  1909 
  1910 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1911 creates a new theory node; implicit merge of thms' signatures is
  1912 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1913 transfer:theory->thm->thm in (rare) cases;
  1914 
  1915 * improved handling of draft signatures / theories; draft thms (and
  1916 ctyps, cterms) are automatically promoted to real ones;
  1917 
  1918 * slightly changed interfaces for oracles: admit many per theory, named
  1919 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1920 
  1921 * print_goals: optional output of const types (set show_consts and
  1922 show_types);
  1923 
  1924 * improved output of warnings (###) and errors (***);
  1925 
  1926 * subgoal_tac displays a warning if the new subgoal has type variables;
  1927 
  1928 * removed old README and Makefiles;
  1929 
  1930 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1931 
  1932 * removed obsolete init_pps and init_database;
  1933 
  1934 * deleted the obsolete tactical STATE, which was declared by
  1935     fun STATE tacfun st = tacfun st st;
  1936 
  1937 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1938 (which abbreviates $HOME);
  1939 
  1940 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1941 use isatool fixseq to adapt your ML programs (this works for fully
  1942 qualified references to the Sequence structure only!);
  1943 
  1944 * use_thy no longer requires writable current directory; it always
  1945 reloads .ML *and* .thy file, if either one is out of date;
  1946 
  1947 
  1948 *** Classical Reasoner ***
  1949 
  1950 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1951 tactics that use classical reasoning to simplify a subgoal without
  1952 splitting it into several subgoals;
  1953 
  1954 * Safe_tac: like safe_tac but uses the default claset;
  1955 
  1956 
  1957 *** Simplifier ***
  1958 
  1959 * added simplification meta rules:
  1960     (asm_)(full_)simplify: simpset -> thm -> thm;
  1961 
  1962 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1963 logics (again);
  1964 
  1965 * added prems argument to simplification procedures;
  1966 
  1967 * HOL, FOL, ZF: added infix function `addsplits':
  1968   instead of `<simpset> setloop (split_tac <thms>)'
  1969   you can simply write `<simpset> addsplits <thms>'
  1970 
  1971 
  1972 *** Syntax ***
  1973 
  1974 * TYPE('a) syntax for type reflection terms;
  1975 
  1976 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1977 
  1978 * pretty printer: changed order of mixfix annotation preference (again!);
  1979 
  1980 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1981 
  1982 
  1983 *** HOL ***
  1984 
  1985 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1986   with `addloop' of the simplifier to faciliate case splitting in premises.
  1987 
  1988 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1989 
  1990 * HOL/Auth: new protocol proofs including some for the Internet
  1991   protocol TLS;
  1992 
  1993 * HOL/Map: new theory of `maps' a la VDM;
  1994 
  1995 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1996 cancelling out common nat summands from =, <, <= (in)equalities, or
  1997 differences; simplification procedures nat_cancel_factor for
  1998 cancelling common factor from =, <, <= (in)equalities over natural
  1999 sums; nat_cancel contains both kinds of procedures, it is installed by
  2000 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2001 
  2002 * HOL/simplifier: terms of the form
  2003   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2004   are rewritten to
  2005   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2006   and those of the form
  2007   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2008   are rewritten to
  2009   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2010 
  2011 * HOL/datatype
  2012   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2013 
  2014   P(t_case f1 ... fn x) =
  2015      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2016         ...
  2017        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2018      )
  2019 
  2020   and a theorem `split_t_case_asm' of the form
  2021 
  2022   P(t_case f1 ... fn x) =
  2023     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2024         ...
  2025        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2026      )
  2027   which can be added to a simpset via `addsplits'. The existing theorems
  2028   expand_list_case and expand_option_case have been renamed to
  2029   split_list_case and split_option_case.
  2030 
  2031 * HOL/Arithmetic:
  2032   - `pred n' is automatically converted to `n-1'.
  2033     Users are strongly encouraged not to use `pred' any longer,
  2034     because it will disappear altogether at some point.
  2035   - Users are strongly encouraged to write "0 < n" rather than
  2036     "n ~= 0". Theorems and proof tools have been modified towards this
  2037     `standard'.
  2038 
  2039 * HOL/Lists:
  2040   the function "set_of_list" has been renamed "set" (and its theorems too);
  2041   the function "nth" now takes its arguments in the reverse order and
  2042   has acquired the infix notation "!" as in "xs!n".
  2043 
  2044 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2045 
  2046 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2047   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2048 
  2049 * HOL/record: extensible records with schematic structural subtyping
  2050 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2051 still lacks various theorems and concrete record syntax;
  2052 
  2053 
  2054 *** HOLCF ***
  2055 
  2056 * removed "axioms" and "generated by" sections;
  2057 
  2058 * replaced "ops" section by extended "consts" section, which is capable of
  2059   handling the continuous function space "->" directly;
  2060 
  2061 * domain package:
  2062   . proves theorems immediately and stores them in the theory,
  2063   . creates hierachical name space,
  2064   . now uses normal mixfix annotations (instead of cinfix...),
  2065   . minor changes to some names and values (for consistency),
  2066   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2067   . separator between mutual domain defs: changed "," to "and",
  2068   . improved handling of sort constraints;  now they have to
  2069     appear on the left-hand side of the equations only;
  2070 
  2071 * fixed LAM <x,y,zs>.b syntax;
  2072 
  2073 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2074 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2075 
  2076 
  2077 *** FOL and ZF ***
  2078 
  2079 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2080   with `addloop' of the simplifier to faciliate case splitting in premises.
  2081 
  2082 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2083 in HOL, they strip ALL and --> from proved theorems;
  2084 
  2085 
  2086 
  2087 New in Isabelle94-8 (May 1997)
  2088 ------------------------------
  2089 
  2090 *** General Changes ***
  2091 
  2092 * new utilities to build / run / maintain Isabelle etc. (in parts
  2093 still somewhat experimental); old Makefiles etc. still functional;
  2094 
  2095 * new 'Isabelle System Manual';
  2096 
  2097 * INSTALL text, together with ./configure and ./build scripts;
  2098 
  2099 * reimplemented type inference for greater efficiency, better error
  2100 messages and clean internal interface;
  2101 
  2102 * prlim command for dealing with lots of subgoals (an easier way of
  2103 setting goals_limit);
  2104 
  2105 
  2106 *** Syntax ***
  2107 
  2108 * supports alternative (named) syntax tables (parser and pretty
  2109 printer); internal interface is provided by add_modesyntax(_i);
  2110 
  2111 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2112 be used in conjunction with the Isabelle symbol font; uses the
  2113 "symbols" syntax table;
  2114 
  2115 * added token_translation interface (may translate name tokens in
  2116 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2117 the current print_mode); IMPORTANT: user print translation functions
  2118 are responsible for marking newly introduced bounds
  2119 (Syntax.mark_boundT);
  2120 
  2121 * token translations for modes "xterm" and "xterm_color" that display
  2122 names in bold, underline etc. or colors (which requires a color
  2123 version of xterm);
  2124 
  2125 * infixes may now be declared with names independent of their syntax;
  2126 
  2127 * added typed_print_translation (like print_translation, but may
  2128 access type of constant);
  2129 
  2130 
  2131 *** Classical Reasoner ***
  2132 
  2133 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2134 some limitations.  Blast_tac...
  2135   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2136   + ignores elimination rules that don't have the correct format
  2137         (the conclusion MUST be a formula variable)
  2138   + ignores types, which can make HOL proofs fail
  2139   + rules must not require higher-order unification, e.g. apply_type in ZF
  2140     [message "Function Var's argument not a bound variable" relates to this]
  2141   + its proof strategy is more general but can actually be slower
  2142 
  2143 * substitution with equality assumptions no longer permutes other
  2144 assumptions;
  2145 
  2146 * minor changes in semantics of addafter (now called addaltern); renamed
  2147 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2148 (and access functions for it);
  2149 
  2150 * improved combination of classical reasoner and simplifier:
  2151   + functions for handling clasimpsets
  2152   + improvement of addss: now the simplifier is called _after_ the
  2153     safe steps.
  2154   + safe variant of addss called addSss: uses safe simplifications
  2155     _during_ the safe steps. It is more complete as it allows multiple
  2156     instantiations of unknowns (e.g. with slow_tac).
  2157 
  2158 *** Simplifier ***
  2159 
  2160 * added interface for simplification procedures (functions that
  2161 produce *proven* rewrite rules on the fly, depending on current
  2162 redex);
  2163 
  2164 * ordering on terms as parameter (used for ordered rewriting);
  2165 
  2166 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2167 
  2168 * the solver is now split into a safe and an unsafe part.
  2169 This should be invisible for the normal user, except that the
  2170 functions setsolver and addsolver have been renamed to setSolver and
  2171 addSolver; added safe_asm_full_simp_tac;
  2172 
  2173 
  2174 *** HOL ***
  2175 
  2176 * a generic induction tactic `induct_tac' which works for all datatypes and
  2177 also for type `nat';
  2178 
  2179 * a generic case distinction tactic `exhaust_tac' which works for all
  2180 datatypes and also for type `nat';
  2181 
  2182 * each datatype comes with a function `size';
  2183 
  2184 * patterns in case expressions allow tuple patterns as arguments to
  2185 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2186 
  2187 * primrec now also works with type nat;
  2188 
  2189 * recdef: a new declaration form, allows general recursive functions to be
  2190 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2191 
  2192 * the constant for negation has been renamed from "not" to "Not" to
  2193 harmonize with FOL, ZF, LK, etc.;
  2194 
  2195 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2196 infinite lists;
  2197 
  2198 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2199 
  2200 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2201 problems in commutative rings, using axiomatic type classes for + and *;
  2202 
  2203 * more examples in HOL/MiniML and HOL/Auth;
  2204 
  2205 * more default rewrite rules for quantifiers, union/intersection;
  2206 
  2207 * a new constant `arbitrary == @x.False';
  2208 
  2209 * HOLCF/IOA replaces old HOL/IOA;
  2210 
  2211 * HOLCF changes: derived all rules and arities
  2212   + axiomatic type classes instead of classes
  2213   + typedef instead of faking type definitions
  2214   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2215   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2216   + eliminated the types void, one, tr
  2217   + use unit lift and bool lift (with translations) instead of one and tr
  2218   + eliminated blift from Lift3.thy (use Def instead of blift)
  2219   all eliminated rules are derived as theorems --> no visible changes ;
  2220 
  2221 
  2222 *** ZF ***
  2223 
  2224 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2225 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2226 as ZF_cs addSIs [equalityI];
  2227 
  2228 
  2229 
  2230 New in Isabelle94-7 (November 96)
  2231 ---------------------------------
  2232 
  2233 * allowing negative levels (as offsets) in prlev and choplev;
  2234 
  2235 * super-linear speedup for large simplifications;
  2236 
  2237 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2238 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2239 FAIL); can suppress it using the command Delsimps (ex_simps @
  2240 all_simps); De Morgan laws are also now included, by default;
  2241 
  2242 * improved printing of ==>  :  ~:
  2243 
  2244 * new object-logic "Sequents" adds linear logic, while replacing LK
  2245 and Modal (thanks to Sara Kalvala);
  2246 
  2247 * HOL/Auth: correctness proofs for authentication protocols;
  2248 
  2249 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2250 examples on HOL/Auth);
  2251 
  2252 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2253 the rewriter and classical reasoner simultaneously;
  2254 
  2255 * function uresult no longer returns theorems in "standard" format;
  2256 regain previous version by: val uresult = standard o uresult;
  2257 
  2258 
  2259 
  2260 New in Isabelle94-6
  2261 -------------------
  2262 
  2263 * oracles -- these establish an interface between Isabelle and trusted
  2264 external reasoners, which may deliver results as theorems;
  2265 
  2266 * proof objects (in particular record all uses of oracles);
  2267 
  2268 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2269 
  2270 * "constdefs" section in theory files;
  2271 
  2272 * "primrec" section (HOL) no longer requires names;
  2273 
  2274 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2275 
  2276 
  2277 
  2278 New in Isabelle94-5
  2279 -------------------
  2280 
  2281 * reduced space requirements;
  2282 
  2283 * automatic HTML generation from theories;
  2284 
  2285 * theory files no longer require "..." (quotes) around most types;
  2286 
  2287 * new examples, including two proofs of the Church-Rosser theorem;
  2288 
  2289 * non-curried (1994) version of HOL is no longer distributed;
  2290 
  2291 
  2292 
  2293 New in Isabelle94-4
  2294 -------------------
  2295 
  2296 * greatly reduced space requirements;
  2297 
  2298 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2299 
  2300 * searchable theorem database (see the section "Retrieving theorems" on
  2301 page 8 of the Reference Manual);
  2302 
  2303 * new examples, including Grabczewski's monumental case study of the
  2304 Axiom of Choice;
  2305 
  2306 * The previous version of HOL renamed to Old_HOL;
  2307 
  2308 * The new version of HOL (previously called CHOL) uses a curried syntax
  2309 for functions.  Application looks like f a b instead of f(a,b);
  2310 
  2311 * Mutually recursive inductive definitions finally work in HOL;
  2312 
  2313 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2314 translates to the operator "split";
  2315 
  2316 
  2317 
  2318 New in Isabelle94-3
  2319 -------------------
  2320 
  2321 * new infix operator, addss, allowing the classical reasoner to
  2322 perform simplification at each step of its search.  Example:
  2323         fast_tac (cs addss ss)
  2324 
  2325 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2326 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2327 look like (a,b) instead of <a,b>;
  2328 
  2329 * PLEASE NOTE: CHOL will eventually replace HOL!
  2330 
  2331 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2332 It translates to the operator "split".  A new theory of integers is available;
  2333 
  2334 * In ZF, integer numerals now denote two's-complement binary integers.
  2335 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2336 
  2337 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2338 of the Axiom of Choice;
  2339 
  2340 
  2341 
  2342 New in Isabelle94-2
  2343 -------------------
  2344 
  2345 * Significantly faster resolution;
  2346 
  2347 * the different sections in a .thy file can now be mixed and repeated
  2348 freely;
  2349 
  2350 * Database of theorems for FOL, HOL and ZF.  New
  2351 commands including qed, qed_goal and bind_thm store theorems in the database.
  2352 
  2353 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2354 a given theory (thms_of), or find out what theory a theorem was proved in
  2355 (theory_of_thm);
  2356 
  2357 * Bugs fixed in the inductive definition and datatype packages;
  2358 
  2359 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2360 and HOL_dup_cs obsolete;
  2361 
  2362 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2363 have been removed;
  2364 
  2365 * Simpler definition of function space in ZF;
  2366 
  2367 * new results about cardinal and ordinal arithmetic in ZF;
  2368 
  2369 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2370 types;
  2371 
  2372 
  2373 $Id$