NEWS
author nipkow
Tue Feb 25 19:08:15 2003 +0100 (2003-02-25)
changeset 13829 af0218406395
parent 13824 e4d8dea6dfc2
child 13835 12b2ffbe543a
permissions -rw-r--r--
*** empty log message ***
     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   - You can limit the number of recursive invocations of the simplifier
    41     during conditional rewriting (where the simplifie tries to solve the
    42     conditions before applying the rewrite rule):
    43     ML "simp_depth_limit := n"
    44     where n is an integer. Thus you can force termination where previously
    45     the simplifier would diverge.
    46 
    47 
    48 * Pure: New flag for triggering if the overall goal of a proof state should
    49 be printed:
    50    PG menu: Isabelle/Isar -> Settigs -> Show Main Goal
    51 (ML: Proof.show_main_goal).
    52 
    53 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
    54 rules whose conclusion matches subgoal 1:
    55       PG menu: Isabelle/Isar -> Show me -> matching rules
    56 The rules are ordered by how closely they match the subgoal.
    57 In particular, rules that solve a subgoal outright are displayed first
    58 (or rather last, the way they are printed).
    59 (ML: ProofGeneral.print_intros())
    60 
    61 * Pure: New flag trace_unify_fail causes unification to print
    62 diagnostic information (PG: in trace buffer) when it fails. This is
    63 useful for figuring out why single step proofs like rule, erule or
    64 assumption failed.
    65 
    66 * Pure: Locale specifications now produce predicate definitions
    67 according to the body of text (covering assumptions modulo local
    68 definitions); predicate "loc_axioms" covers newly introduced text,
    69 while "loc" is cumulative wrt. all included locale expressions; the
    70 latter view is presented only on export into the global theory
    71 context; potential INCOMPATIBILITY, use "(open)" option to fall back
    72 on the old view without predicates;
    73 
    74 * Pure: predefined locales "var" and "struct" are useful for sharing
    75 parameters (as in CASL, for example); just specify something like
    76 ``var x + var y + struct M'' as import;
    77 
    78 * Pure: improved thms_containing: proper indexing of facts instead of
    79 raw theorems; check validity of results wrt. current name space;
    80 include local facts of proof configuration (also covers active
    81 locales), cover fixed variables in index; may use "_" in term
    82 specification; an optional limit for the number of printed facts may
    83 be given (the default is 40);
    84 
    85 * Pure: disallow duplicate fact bindings within new-style theory files
    86 (batch-mode only);
    87 
    88 * Provers: improved induct method: assumptions introduced by case
    89 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
    90 the goal statement); "foo" still refers to all facts collectively;
    91 
    92 * Provers: the function blast.overloaded has been removed: all constants
    93 are regarded as potentially overloaded, which improves robustness in exchange
    94 for slight decrease in efficiency;
    95 
    96 * Provers/linorder: New generic prover for transitivity reasoning over
    97 linear orders.  Note: this prover is not efficient!
    98 
    99 * Isar: preview of problems to finish 'show' now produce an error
   100 rather than just a warning (in interactive mode);
   101 
   102 
   103 *** HOL ***
   104 
   105 * GroupTheory: new, experimental summation operator for abelian groups.
   106 
   107 * New tactic "trans_tac" and method "trans" instantiate
   108 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   109 "<=", "<" and "="). 
   110 
   111 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main 
   112 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   113 
   114 * 'typedef' command has new option "open" to suppress the set
   115 definition;
   116 
   117 * functions Min and Max on finite sets have been introduced (theory
   118 Finite_Set);
   119 
   120 * attribute [symmetric] now works for relations as well; it turns
   121 (x,y) : R^-1 into (y,x) : R, and vice versa;
   122 
   123 * arith(_tac) now produces a counter example if it cannot prove a theorem.
   124   In ProofGeneral the counter example appears in the trace buffer.
   125 
   126 * arith(_tac) does now know about div k and mod k where k is a numeral
   127 of type nat or int. It can solve simple goals like
   128 
   129   "0 < n ==> n div 2 < (n::nat)"
   130 
   131 but fails if divisibility plays a role like in
   132 
   133   "n div 2 + (n+1) div 2 = (n::nat)"
   134 
   135 * simp's arithmetic capabilities have been enhanced a bit: it now
   136 takes ~= in premises into account (by performing a case split);
   137 
   138 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   139 are distributed over a sum of terms;
   140 
   141 * induct over a !!-quantified statement (say !!x1..xn):
   142   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   143 
   144 * GroupTheory: converted to Isar theories, using locales with implicit structures;
   145 
   146 * Real/HahnBanach: updated and adapted to locales;
   147 
   148 
   149 *** ZF ***
   150 
   151 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   152 universe, etc.);
   153 
   154 * Main ZF: many theories converted to new-style format;
   155 
   156 
   157 *** ML ***
   158 
   159 * Pure: Tactic.prove provides sane interface for internal proofs;
   160 omits the infamous "standard" operation, so this is more appropriate
   161 than prove_goalw_cterm in many situations (e.g. in simprocs);
   162 
   163 * Pure: improved error reporting of simprocs;
   164 
   165 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   166 up simprocs;
   167 
   168 
   169 
   170 New in Isabelle2002 (March 2002)
   171 --------------------------------
   172 
   173 *** Document preparation ***
   174 
   175 * greatly simplified document preparation setup, including more
   176 graceful interpretation of isatool usedir -i/-d/-D options, and more
   177 instructive isatool mkdir; users should basically be able to get
   178 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   179 users may run a separate document processing stage manually like this:
   180 "isatool usedir -D output HOL Test && isatool document Test/output";
   181 
   182 * theory dependency graph may now be incorporated into documents;
   183 isatool usedir -g true will produce session_graph.eps/.pdf for use
   184 with \includegraphics of LaTeX;
   185 
   186 * proper spacing of consecutive markup elements, especially text
   187 blocks after section headings;
   188 
   189 * support bold style (for single symbols only), input syntax is like
   190 this: "\<^bold>\<alpha>" or "\<^bold>A";
   191 
   192 * \<bullet> is now output as bold \cdot by default, which looks much
   193 better in printed text;
   194 
   195 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   196 note that these symbols are currently unavailable in Proof General /
   197 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   198 
   199 * isatool latex no longer depends on changed TEXINPUTS, instead
   200 isatool document copies the Isabelle style files to the target
   201 location;
   202 
   203 
   204 *** Isar ***
   205 
   206 * Pure/Provers: improved proof by cases and induction;
   207   - 'case' command admits impromptu naming of parameters (such as
   208     "case (Suc n)");
   209   - 'induct' method divinates rule instantiation from the inductive
   210     claim; no longer requires excessive ?P bindings for proper
   211     instantiation of cases;
   212   - 'induct' method properly enumerates all possibilities of set/type
   213     rules; as a consequence facts may be also passed through *type*
   214     rules without further ado;
   215   - 'induct' method now derives symbolic cases from the *rulified*
   216     rule (before it used to rulify cases stemming from the internal
   217     atomized version); this means that the context of a non-atomic
   218     statement becomes is included in the hypothesis, avoiding the
   219     slightly cumbersome show "PROP ?case" form;
   220   - 'induct' may now use elim-style induction rules without chaining
   221     facts, using ``missing'' premises from the goal state; this allows
   222     rules stemming from inductive sets to be applied in unstructured
   223     scripts, while still benefitting from proper handling of non-atomic
   224     statements; NB: major inductive premises need to be put first, all
   225     the rest of the goal is passed through the induction;
   226   - 'induct' proper support for mutual induction involving non-atomic
   227     rule statements (uses the new concept of simultaneous goals, see
   228     below);
   229   - append all possible rule selections, but only use the first
   230     success (no backtracking);
   231   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   232   - undeclared rule case names default to numbers 1, 2, 3, ...;
   233   - added 'print_induct_rules' (covered by help item in recent Proof
   234     General versions);
   235   - moved induct/cases attributes to Pure, methods to Provers;
   236   - generic method setup instantiated for FOL and HOL;
   237 
   238 * Pure: support multiple simultaneous goal statements, for example
   239 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   240 meta-level mechanism, this acts as if several individual goals had
   241 been stated separately; in particular common proof methods need to be
   242 repeated in order to cover all claims; note that a single elimination
   243 step is *not* sufficient to establish the two conjunctions, so this
   244 fails:
   245 
   246   assume "A & B" then have A and B ..   (*".." fails*)
   247 
   248 better use "obtain" in situations as above; alternative refer to
   249 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   250 
   251 * Pure: proper integration with ``locales''; unlike the original
   252 version by Florian Kammüller, Isar locales package high-level proof
   253 contexts rather than raw logical ones (e.g. we admit to include
   254 attributes everywhere); operations on locales include merge and
   255 rename; support for implicit arguments (``structures''); simultaneous
   256 type-inference over imports and text; see also HOL/ex/Locales.thy for
   257 some examples;
   258 
   259 * Pure: the following commands have been ``localized'', supporting a
   260 target locale specification "(in name)": 'lemma', 'theorem',
   261 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   262 stored both within the locale and at the theory level (exported and
   263 qualified by the locale name);
   264 
   265 * Pure: theory goals may now be specified in ``long'' form, with
   266 ad-hoc contexts consisting of arbitrary locale elements. for example
   267 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   268 definitions may be given, too); the result is a meta-level rule with
   269 the context elements being discharged in the obvious way;
   270 
   271 * Pure: new proof command 'using' allows to augment currently used
   272 facts after a goal statement ('using' is syntactically analogous to
   273 'apply', but acts on the goal's facts only); this allows chained facts
   274 to be separated into parts given before and after a claim, as in
   275 ``from a and b have C using d and e <proof>'';
   276 
   277 * Pure: renamed "antecedent" case to "rule_context";
   278 
   279 * Pure: new 'judgment' command records explicit information about the
   280 object-logic embedding (used by several tools internally); no longer
   281 use hard-wired "Trueprop";
   282 
   283 * Pure: added 'corollary' command;
   284 
   285 * Pure: fixed 'token_translation' command;
   286 
   287 * Pure: removed obsolete 'exported' attribute;
   288 
   289 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   290 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   291 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   292 
   293 * Pure: method 'atomize' presents local goal premises as object-level
   294 statements (atomic meta-level propositions); setup controlled via
   295 rewrite rules declarations of 'atomize' attribute; example
   296 application: 'induct' method with proper rule statements in improper
   297 proof *scripts*;
   298 
   299 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   300 now consider the syntactic context of assumptions, giving a better
   301 chance to get type-inference of the arguments right (this is
   302 especially important for locales);
   303 
   304 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   305 mode;
   306 
   307 * Pure/obtain: the formal conclusion "thesis", being marked as
   308 ``internal'', may no longer be reference directly in the text;
   309 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   310 situations;
   311 
   312 * Pure: generic 'sym' attribute which declares a rule both as pure
   313 'elim?' and for the 'symmetric' operation;
   314 
   315 * Pure: marginal comments ``--'' may now occur just anywhere in the
   316 text; the fixed correlation with particular command syntax has been
   317 discontinued;
   318 
   319 * Pure: new method 'rules' is particularly well-suited for proof
   320 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   321 but often produces more compact proof terms with less detours;
   322 
   323 * Pure/Provers/classical: simplified integration with pure rule
   324 attributes and methods; the classical "intro?/elim?/dest?"
   325 declarations coincide with the pure ones; the "rule" method no longer
   326 includes classically swapped intros; "intro" and "elim" methods no
   327 longer pick rules from the context; also got rid of ML declarations
   328 AddXIs/AddXEs/AddXDs; all of this has some potential for
   329 INCOMPATIBILITY;
   330 
   331 * Provers/classical: attribute 'swapped' produces classical inversions
   332 of introduction rules;
   333 
   334 * Provers/simplifier: 'simplified' attribute may refer to explicit
   335 rules instead of full simplifier context; 'iff' attribute handles
   336 conditional rules;
   337 
   338 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   339 
   340 * HOL: 'recdef' now fails on unfinished automated proofs, use
   341 "(permissive)" option to recover old behavior;
   342 
   343 * HOL: 'inductive' no longer features separate (collective) attributes
   344 for 'intros' (was found too confusing);
   345 
   346 * HOL: properly declared induction rules less_induct and
   347 wf_induct_rule;
   348 
   349 
   350 *** HOL ***
   351 
   352 * HOL: moved over to sane numeral syntax; the new policy is as
   353 follows:
   354 
   355   - 0 and 1 are polymorphic constants, which are defined on any
   356   numeric type (nat, int, real etc.);
   357 
   358   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   359   binary representation internally;
   360 
   361   - type nat has special constructor Suc, and generally prefers Suc 0
   362   over 1::nat and Suc (Suc 0) over 2::nat;
   363 
   364 This change may cause significant problems of INCOMPATIBILITY; here
   365 are some hints on converting existing sources:
   366 
   367   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   368   entities, so expressions involving "-" (unary or binary minus) need
   369   to be spaced properly;
   370 
   371   - existing occurrences of "1" may need to be constraint "1::nat" or
   372   even replaced by Suc 0; similar for old "2";
   373 
   374   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   375 
   376   - remove all special provisions on numerals in proofs;
   377 
   378 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   379 representation (depends on bin_arith_simps in the default context);
   380 
   381 * HOL: symbolic syntax for x^2 (numeral 2);
   382 
   383 * HOL: the class of all HOL types is now called "type" rather than
   384 "term"; INCOMPATIBILITY, need to adapt references to this type class
   385 in axclass/classes, instance/arities, and (usually rare) occurrences
   386 in typings (of consts etc.); internally the class is called
   387 "HOL.type", ML programs should refer to HOLogic.typeS;
   388 
   389 * HOL/record package improvements:
   390   - new derived operations "fields" to build a partial record section,
   391     "extend" to promote a fixed record to a record scheme, and
   392     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   393     declared as simp by default;
   394   - shared operations ("more", "fields", etc.) now need to be always
   395     qualified) --- potential INCOMPATIBILITY;
   396   - removed "make_scheme" operations (use "make" with "extend") --
   397     INCOMPATIBILITY;
   398   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   399   - provides cases/induct rules for use with corresponding Isar
   400     methods (for concrete records, record schemes, concrete more
   401     parts, and schematic more parts -- in that order);
   402   - internal definitions directly based on a light-weight abstract
   403     theory of product types over typedef rather than datatype;
   404 
   405 * HOL: generic code generator for generating executable ML code from
   406 specifications; specific support for HOL constructs such as inductive
   407 datatypes and sets, as well as recursive functions; can be invoked
   408 via 'generate_code' theory section;
   409 
   410 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   411 
   412 * HOL: consolidated and renamed several theories.  In particular:
   413 	Ord.thy has been absorbed into HOL.thy
   414 	String.thy has been absorbed into List.thy
   415  
   416 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   417 (beware of argument permutation!);
   418 
   419 * HOL: linorder_less_split superseded by linorder_cases;
   420 
   421 * HOL/List: "nodups" renamed to "distinct";
   422 
   423 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   424 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   425   - Ex_def has changed, now need to use some_eq_ex
   426 
   427 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   428 in this (rare) case use:
   429 
   430   delSWrapper "split_all_tac"
   431   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   432 
   433 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   434 MAY FAIL;
   435 
   436 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   437 Isabelle's type classes, ^ on functions and relations has too general
   438 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   439 necessary to attach explicit type constraints;
   440 
   441 * HOL/Relation: the prefix name of the infix "O" has been changed from
   442 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   443 renamed accordingly (eg "compI" -> "rel_compI").
   444 
   445 * HOL: syntax translations now work properly with numerals and records
   446 expressions;
   447 
   448 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   449 of "lam" -- INCOMPATIBILITY;
   450 
   451 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   452 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   453 renamed "Product_Type.unit";
   454 
   455 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   456 
   457 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   458 the "cases" method);
   459 
   460 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   461 Florian Kammüller);
   462 
   463 * HOL/IMP: updated and converted to new-style theory format; several
   464 parts turned into readable document, with proper Isar proof texts and
   465 some explanations (by Gerwin Klein);
   466 
   467 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   468 
   469 * HOL-Hyperreal is now a logic image;
   470 
   471 
   472 *** HOLCF ***
   473 
   474 * Isar: consts/constdefs supports mixfix syntax for continuous
   475 operations;
   476 
   477 * Isar: domain package adapted to new-style theory format, e.g. see
   478 HOLCF/ex/Dnat.thy;
   479 
   480 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   481 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   482 lift.induct_tac, always use UU instead of Undef;
   483 
   484 * HOLCF/IMP: updated and converted to new-style theory;
   485 
   486 
   487 *** ZF ***
   488 
   489 * Isar: proper integration of logic-specific tools and packages,
   490 including theory commands '(co)inductive', '(co)datatype',
   491 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   492 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   493 
   494 * theory Main no longer includes AC; for the Axiom of Choice, base
   495 your theory on Main_ZFC;
   496 
   497 * the integer library now covers quotients and remainders, with many
   498 laws relating division to addition, multiplication, etc.;
   499 
   500 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   501 typeless version of the formalism;
   502 
   503 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   504 format;
   505 
   506 * ZF/Induct: new directory for examples of inductive definitions,
   507 including theory Multiset for multiset orderings; converted to
   508 new-style theory format;
   509 
   510 * ZF: many new theorems about lists, ordinals, etc.;
   511 
   512 
   513 *** General ***
   514 
   515 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   516 variable proof controls level of detail: 0 = no proofs (only oracle
   517 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   518 also ref manual for further ML interfaces;
   519 
   520 * Pure/axclass: removed obsolete ML interface
   521 goal_subclass/goal_arity;
   522 
   523 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   524 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   525 separate tokens, so expressions involving minus need to be spaced
   526 properly;
   527 
   528 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   529 rather than "infixl" or "infixr";
   530 
   531 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   532 sort constraint specifications in type inference; e.g. "x::_::foo"
   533 ensures that the type of "x" is of sort "foo" (but not necessarily a
   534 type variable);
   535 
   536 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   537 control output of nested => (types); the default behavior is
   538 "type_brackets";
   539 
   540 * Pure/syntax: builtin parse translation for "_constify" turns valued
   541 tokens into AST constants;
   542 
   543 * Pure/syntax: prefer later declarations of translations and print
   544 translation functions; potential INCOMPATIBILITY: need to reverse
   545 multiple declarations for same syntax element constant;
   546 
   547 * Pure/show_hyps reset by default (in accordance to existing Isar
   548 practice);
   549 
   550 * Provers/classical: renamed addaltern to addafter, addSaltern to
   551 addSafter;
   552 
   553 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   554 as well;
   555 
   556 * system: tested support for MacOS X; should be able to get Isabelle +
   557 Proof General to work in a plain Terminal after installing Poly/ML
   558 (e.g. from the Isabelle distribution area) and GNU bash alone
   559 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   560 support requires further installations, e.g. from
   561 http://fink.sourceforge.net/);
   562 
   563 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   564 
   565 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   566 of 40 MB), cf. ML_OPTIONS;
   567 
   568 * system: Proof General keywords specification is now part of the
   569 Isabelle distribution (see etc/isar-keywords.el);
   570 
   571 * system: support for persistent Proof General sessions (refrain from
   572 outdating all loaded theories on startup); user may create writable
   573 logic images like this: ``isabelle -q HOL Test'';
   574 
   575 * system: smart selection of Isabelle process versus Isabelle
   576 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   577 run both "isabelle" and "Isabelle" even if file names are badly
   578 damaged (executable inspects the case of the first letter of its own
   579 name); added separate "isabelle-process" and "isabelle-interface";
   580 
   581 * system: refrain from any attempt at filtering input streams; no
   582 longer support ``8bit'' encoding of old isabelle font, instead proper
   583 iso-latin characters may now be used; the related isatools
   584 "symbolinput" and "nonascii" have disappeared as well;
   585 
   586 * system: removed old "xterm" interface (the print modes "xterm" and
   587 "xterm_color" are still available for direct use in a suitable
   588 terminal);
   589 
   590 
   591 
   592 New in Isabelle99-2 (February 2001)
   593 -----------------------------------
   594 
   595 *** Overview of INCOMPATIBILITIES ***
   596 
   597 * HOL: please note that theories in the Library and elsewhere often use the
   598 new-style (Isar) format; to refer to their theorems in an ML script you must
   599 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   600 
   601 * HOL: inductive package no longer splits induction rule aggressively,
   602 but only as far as specified by the introductions given; the old
   603 format may be recovered via ML function complete_split_rule or attribute
   604 'split_rule (complete)';
   605 
   606 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   607 gfp_Tarski to gfp_unfold;
   608 
   609 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   610 
   611 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   612 relation); infix "^^" has been renamed "``"; infix "``" has been
   613 renamed "`"; "univalent" has been renamed "single_valued";
   614 
   615 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   616 operation;
   617 
   618 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   619 
   620 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   621 
   622 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   623 consequence, it is no longer monotonic wrt. the local goal context
   624 (which is now passed through the inductive cases);
   625 
   626 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   627 \<gg> to \<ggreater>;
   628 
   629 
   630 *** Document preparation ***
   631 
   632 * \isabellestyle{NAME} selects version of Isabelle output (currently
   633 available: are "it" for near math-mode best-style output, "sl" for
   634 slanted text style, and "tt" for plain type-writer; if no
   635 \isabellestyle command is given, output is according to slanted
   636 type-writer);
   637 
   638 * support sub/super scripts (for single symbols only), input syntax is
   639 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   640 
   641 * some more standard symbols; see Appendix A of the system manual for
   642 the complete list of symbols defined in isabellesym.sty;
   643 
   644 * improved isabelle style files; more abstract symbol implementation
   645 (should now use \isamath{...} and \isatext{...} in custom symbol
   646 definitions);
   647 
   648 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   649 state; Note that presentation of goal states does not conform to
   650 actual human-readable proof documents.  Please do not include goal
   651 states into document output unless you really know what you are doing!
   652 
   653 * proper indentation of antiquoted output with proportional LaTeX
   654 fonts;
   655 
   656 * no_document ML operator temporarily disables LaTeX document
   657 generation;
   658 
   659 * isatool unsymbolize tunes sources for plain ASCII communication;
   660 
   661 
   662 *** Isar ***
   663 
   664 * Pure: Isar now suffers initial goal statements to contain unbound
   665 schematic variables (this does not conform to actual readable proof
   666 documents, due to unpredictable outcome and non-compositional proof
   667 checking); users who know what they are doing may use schematic goals
   668 for Prolog-style synthesis of proven results;
   669 
   670 * Pure: assumption method (an implicit finishing) now handles actual
   671 rules as well;
   672 
   673 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   674 initial goal, declare "that" only as Pure intro (only for single
   675 steps); the "that" rule assumption may now be involved in implicit
   676 finishing, thus ".." becomes a feasible for trivial obtains;
   677 
   678 * Pure: default proof step now includes 'intro_classes'; thus trivial
   679 instance proofs may be performed by "..";
   680 
   681 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   682 statements as well;
   683 
   684 * Pure: more robust selection of calculational rules;
   685 
   686 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   687 rule (as well as the assumption rule);
   688 
   689 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   690 lemmas, using the graph browser tool;
   691 
   692 * Pure: predict failure of "show" in interactive mode;
   693 
   694 * Pure: 'thms_containing' now takes actual terms as arguments;
   695 
   696 * HOL: improved method 'induct' --- now handles non-atomic goals
   697 (potential INCOMPATIBILITY); tuned error handling;
   698 
   699 * HOL: cases and induct rules now provide explicit hints about the
   700 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   701 any remaining facts are inserted into the goal verbatim;
   702 
   703 * HOL: local contexts (aka cases) may now contain term bindings as
   704 well; the 'cases' and 'induct' methods new provide a ?case binding for
   705 the result to be shown in each case;
   706 
   707 * HOL: added 'recdef_tc' command;
   708 
   709 * isatool convert assists in eliminating legacy ML scripts;
   710 
   711 
   712 *** HOL ***
   713 
   714 * HOL/Library: a collection of generic theories to be used together
   715 with main HOL; the theory loader path already includes this directory
   716 by default; the following existing theories have been moved here:
   717 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   718 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   719 
   720 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   721 modelling and verification task performed in Isabelle/HOL +
   722 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   723 
   724 * HOL/Algebra: special summation operator SUM no longer exists, it has
   725 been replaced by setsum; infix 'assoc' now has priority 50 (like
   726 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   727 'domain', this makes the theory consistent with mathematical
   728 literature;
   729 
   730 * HOL basics: added overloaded operations "inverse" and "divide"
   731 (infix "/"), syntax for generic "abs" operation, generic summation
   732 operator \<Sum>;
   733 
   734 * HOL/typedef: simplified package, provide more useful rules (see also
   735 HOL/subset.thy);
   736 
   737 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   738 now expressed as a proper nested rule (old-style tactic scripts may
   739 require atomize_strip_tac to cope with non-atomic premises);
   740 
   741 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   742 to "split_conv" (old name still available for compatibility);
   743 
   744 * HOL: improved concrete syntax for strings (e.g. allows translation
   745 rules with string literals);
   746 
   747 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   748  and Fleuriot's mechanization of analysis, including the transcendental
   749  functions for the reals;
   750 
   751 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   752 
   753 
   754 *** CTT ***
   755 
   756 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   757 "lam" is displayed as TWO lambda-symbols
   758 
   759 * CTT: theory Main now available, containing everything (that is, Bool
   760 and Arith);
   761 
   762 
   763 *** General ***
   764 
   765 * Pure: the Simplifier has been implemented properly as a derived rule
   766 outside of the actual kernel (at last!); the overall performance
   767 penalty in practical applications is about 50%, while reliability of
   768 the Isabelle inference kernel has been greatly improved;
   769 
   770 * print modes "brackets" and "no_brackets" control output of nested =>
   771 (types) and ==> (props); the default behaviour is "brackets";
   772 
   773 * Provers: fast_tac (and friends) now handle actual object-logic rules
   774 as assumptions as well;
   775 
   776 * system: support Poly/ML 4.0;
   777 
   778 * system: isatool install handles KDE version 1 or 2;
   779 
   780 
   781 
   782 New in Isabelle99-1 (October 2000)
   783 ----------------------------------
   784 
   785 *** Overview of INCOMPATIBILITIES ***
   786 
   787 * HOL: simplification of natural numbers is much changed; to partly
   788 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   789 issue the following ML commands:
   790 
   791   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   792   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   793 
   794 * HOL: simplification no longer dives into case-expressions; this is
   795 controlled by "t.weak_case_cong" for each datatype t;
   796 
   797 * HOL: nat_less_induct renamed to less_induct;
   798 
   799 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   800 fixsome to patch .thy and .ML sources automatically;
   801 
   802   select_equality  -> some_equality
   803   select_eq_Ex     -> some_eq_ex
   804   selectI2EX       -> someI2_ex
   805   selectI2         -> someI2
   806   selectI          -> someI
   807   select1_equality -> some1_equality
   808   Eps_sym_eq       -> some_sym_eq_trivial
   809   Eps_eq           -> some_eq_trivial
   810 
   811 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   812 
   813 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   814 instead);
   815 
   816 * HOL: the recursion equations generated by 'recdef' are now called
   817 f.simps instead of f.rules;
   818 
   819 * HOL: qed_spec_mp now also handles bounded ALL as well;
   820 
   821 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   822 sometimes be needed;
   823 
   824 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   825 
   826 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   827 
   828 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   829 product is now "<*>" instead of "Times"; the lexicographic product is
   830 now "<*lex*>" instead of "**";
   831 
   832 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   833 of main HOL, but was unused); better use HOL's datatype package;
   834 
   835 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   836 the old syntax may be recovered as follows:
   837 
   838   syntax (symbols)
   839     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   840       (infixl "\\<oplus>" 100)
   841 
   842 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   843 
   844 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   845 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   846 internally;
   847 
   848 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   849 changed from A/r to A//r;
   850 
   851 * ZF: new treatment of arithmetic (nat & int) may break some old
   852 proofs;
   853 
   854 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   855 rulify -> rule_format, elimify -> elim_format, ...);
   856 
   857 * Isar/Provers: intro/elim/dest attributes changed; renamed
   858 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   859 should have to change intro!! to intro? only); replaced "delrule" by
   860 "rule del";
   861 
   862 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   863 
   864 * Provers: strengthened force_tac by using new first_best_tac;
   865 
   866 * LaTeX document preparation: several changes of isabelle.sty (see
   867 lib/texinputs);
   868 
   869 
   870 *** Document preparation ***
   871 
   872 * formal comments (text blocks etc.) in new-style theories may now
   873 contain antiquotations of thm/prop/term/typ/text to be presented
   874 according to latex print mode; concrete syntax is like this:
   875 @{term[show_types] "f(x) = a + x"};
   876 
   877 * isatool mkdir provides easy setup of Isabelle session directories,
   878 including proper document sources;
   879 
   880 * generated LaTeX sources are now deleted after successful run
   881 (isatool document -c); may retain a copy somewhere else via -D option
   882 of isatool usedir;
   883 
   884 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   885 style files, achieving self-contained LaTeX sources and simplifying
   886 LaTeX debugging;
   887 
   888 * old-style theories now produce (crude) LaTeX output as well;
   889 
   890 * browser info session directories are now self-contained (may be put
   891 on WWW server seperately); improved graphs of nested sessions; removed
   892 graph for 'all sessions';
   893 
   894 * several improvements in isabelle style files; \isabellestyle{it}
   895 produces fake math mode output; \isamarkupheader is now \section by
   896 default; see lib/texinputs/isabelle.sty etc.;
   897 
   898 
   899 *** Isar ***
   900 
   901 * Isar/Pure: local results and corresponding term bindings are now
   902 subject to Hindley-Milner polymorphism (similar to ML); this
   903 accommodates incremental type-inference very nicely;
   904 
   905 * Isar/Pure: new derived language element 'obtain' supports
   906 generalized existence reasoning;
   907 
   908 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   909 support accumulation of results, without applying any rules yet;
   910 useful to collect intermediate results without explicit name
   911 references, and for use with transitivity rules with more than 2
   912 premises;
   913 
   914 * Isar/Pure: scalable support for case-analysis type proofs: new
   915 'case' language element refers to local contexts symbolically, as
   916 produced by certain proof methods; internally, case names are attached
   917 to theorems as "tags";
   918 
   919 * Isar/Pure: theory command 'hide' removes declarations from
   920 class/type/const name spaces;
   921 
   922 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   923 indicate potential overloading;
   924 
   925 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   926 
   927 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   928 "{a,b,c}" instead of {a,b,c};
   929 
   930 * Isar/Pure now provides its own version of intro/elim/dest
   931 attributes; useful for building new logics, but beware of confusion
   932 with the version in Provers/classical;
   933 
   934 * Isar/Pure: the local context of (non-atomic) goals is provided via
   935 case name 'antecedent';
   936 
   937 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   938 to the current context is now done automatically);
   939 
   940 * Isar/Pure: theory command 'method_setup' provides a simple interface
   941 for definining proof methods in ML;
   942 
   943 * Isar/Provers: intro/elim/dest attributes changed; renamed
   944 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   945 most cases, one should have to change intro!! to intro? only);
   946 replaced "delrule" by "rule del";
   947 
   948 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   949 'symmetric' attribute (the latter supercedes [RS sym]);
   950 
   951 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   952 method modifier); 'simp' method: 'only:' modifier removes loopers as
   953 well (including splits);
   954 
   955 * Isar/Provers: Simplifier and Classical methods now support all kind
   956 of modifiers used in the past, including 'cong', 'iff', etc.
   957 
   958 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   959 of Simplifier and Classical reasoner);
   960 
   961 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   962 now support named cases; major packages (inductive, datatype, primrec,
   963 recdef) support case names and properly name parameters;
   964 
   965 * Isar/HOL: new transitivity rules for substitution in inequalities --
   966 monotonicity conditions are extracted to be proven at end of
   967 calculations;
   968 
   969 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   970 method anyway;
   971 
   972 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   973 split_if split_if_asm; datatype package provides theorems foo.splits =
   974 foo.split foo.split_asm for each datatype;
   975 
   976 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   977 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   978 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   979 use "(cases (simplified))" method in proper proof texts);
   980 
   981 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   982 
   983 * Isar: names of theorems etc. may be natural numbers as well;
   984 
   985 * Isar: 'pr' command: optional arguments for goals_limit and
   986 ProofContext.prems_limit; no longer prints theory contexts, but only
   987 proof states;
   988 
   989 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   990 additional print modes to be specified; e.g. "pr(latex)" will print
   991 proof state according to the Isabelle LaTeX style;
   992 
   993 * Isar: improved support for emulating tactic scripts, including proof
   994 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   995 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   996 (for HOL datatypes);
   997 
   998 * Isar: simplified (more robust) goal selection of proof methods: 1st
   999 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1000 'proof method scripts' have to be in depth-first order;
  1001 
  1002 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1003 
  1004 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1005 should instead use individual commands for printing items
  1006 (print_commands, print_methods etc.);
  1007 
  1008 * Isar: added 'nothing' --- the empty list of theorems;
  1009 
  1010 
  1011 *** HOL ***
  1012 
  1013 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1014 corresponding virtual machine and a specification of its bytecode
  1015 verifier and a lightweight bytecode verifier, including proofs of
  1016 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1017 Cornelia Pusch (see also the homepage of project Bali at
  1018 http://isabelle.in.tum.de/Bali/);
  1019 
  1020 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1021 Clemens Ballarin;
  1022 
  1023 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1024 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1025 Rasmussen;
  1026 
  1027 * HOL/Lattice: fundamental concepts of lattice theory and order
  1028 structures, including duals, properties of bounds versus algebraic
  1029 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1030 Theorem for complete lattices etc.; may also serve as a demonstration
  1031 for abstract algebraic reasoning using axiomatic type classes, and
  1032 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1033 
  1034 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1035 von Oheimb;
  1036 
  1037 * HOL/IMPP: extension of IMP with local variables and mutually
  1038 recursive procedures, by David von Oheimb;
  1039 
  1040 * HOL/Lambda: converted into new-style theory and document;
  1041 
  1042 * HOL/ex/Multiquote: example of multiple nested quotations and
  1043 anti-quotations -- basically a generalized version of de-Bruijn
  1044 representation; very useful in avoiding lifting of operations;
  1045 
  1046 * HOL/record: added general record equality rule to simpset; fixed
  1047 select-update simplification procedure to handle extended records as
  1048 well; admit "r" as field name;
  1049 
  1050 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1051 other numeric types and also as the identity of groups, rings, etc.;
  1052 
  1053 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1054 Types nat and int belong to this axclass;
  1055 
  1056 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1057    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1058    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1059   two terms #m*u and #n*u are replaced by #(m+n)*u
  1060     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1061   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1062     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1063 
  1064 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1065 powerful prover for predicate logic but knows nothing of clasets; see
  1066 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1067 
  1068 * HOL: new version of "case_tac" subsumes both boolean case split and
  1069 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1070 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1071 
  1072 * HOL: simplification no longer dives into case-expressions: only the
  1073 selector expression is simplified, but not the remaining arms; to
  1074 enable full simplification of case-expressions for datatype t, you may
  1075 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1076 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1077 
  1078 * HOL/recdef: the recursion equations generated by 'recdef' for
  1079 function 'f' are now called f.simps instead of f.rules; if all
  1080 termination conditions are proved automatically, these simplification
  1081 rules are added to the simpset, as in primrec; rules may be named
  1082 individually as well, resulting in a separate list of theorems for
  1083 each equation;
  1084 
  1085 * HOL/While is a new theory that provides a while-combinator. It
  1086 permits the definition of tail-recursive functions without the
  1087 provision of a termination measure. The latter is necessary once the
  1088 invariant proof rule for while is applied.
  1089 
  1090 * HOL: new (overloaded) notation for the set of elements below/above
  1091 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1092 
  1093 * HOL: theorems impI, allI, ballI bound as "strip";
  1094 
  1095 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1096 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1097 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1098 
  1099 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1100 
  1101 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1102 main HOL, but was unused);
  1103 
  1104 * HOL: fewer consts declared as global (e.g. have to refer to
  1105 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1106 
  1107 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1108 in case of overlap with user translations (e.g. judgements over
  1109 tuples); (note that the underlying logical represenation is still
  1110 bogus);
  1111 
  1112 
  1113 *** ZF ***
  1114 
  1115 * ZF: simplification automatically cancels common terms in arithmetic
  1116 expressions over nat and int;
  1117 
  1118 * ZF: new treatment of nat to minimize type-checking: all operators
  1119 coerce their operands to a natural number using the function natify,
  1120 making the algebraic laws unconditional;
  1121 
  1122 * ZF: as above, for int: operators coerce their operands to an integer
  1123 using the function intify;
  1124 
  1125 * ZF: the integer library now contains many of the usual laws for the
  1126 orderings, including $<=, and monotonicity laws for $+ and $*;
  1127 
  1128 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1129 simplification;
  1130 
  1131 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1132 to the simplifier and classical reasoner simultaneously;
  1133 
  1134 
  1135 *** General ***
  1136 
  1137 * Provers: blast_tac now handles actual object-logic rules as
  1138 assumptions; note that auto_tac uses blast_tac internally as well;
  1139 
  1140 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1141 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1142 
  1143 * Provers: delrules now handles destruct rules as well (no longer need
  1144 explicit make_elim);
  1145 
  1146 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1147   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1148 use instead the strong form,
  1149   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1150 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1151 from destruct-rules;
  1152 
  1153 * Provers: Simplifier.easy_setup provides a fast path to basic
  1154 Simplifier setup for new object-logics;
  1155 
  1156 * Pure: AST translation rules no longer require constant head on LHS;
  1157 
  1158 * Pure: improved name spaces: ambiguous output is qualified; support
  1159 for hiding of names;
  1160 
  1161 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1162 XSYMBOL_HOME; no longer need to do manual configuration in most
  1163 situations;
  1164 
  1165 * system: compression of ML heaps images may now be controlled via -c
  1166 option of isabelle and isatool usedir (currently only observed by
  1167 Poly/ML);
  1168 
  1169 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1170 useful for remote X11);
  1171 
  1172 * system: provide TAGS file for Isabelle sources;
  1173 
  1174 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1175 order;
  1176 
  1177 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1178 timing flag supersedes proof_timing and Toplevel.trace;
  1179 
  1180 * ML: new combinators |>> and |>>> for incremental transformations
  1181 with secondary results (e.g. certain theory extensions):
  1182 
  1183 * ML: PureThy.add_defs gets additional argument to indicate potential
  1184 overloading (usually false);
  1185 
  1186 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1187 results;
  1188 
  1189 
  1190 
  1191 New in Isabelle99 (October 1999)
  1192 --------------------------------
  1193 
  1194 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1195 
  1196 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1197 are no longer simplified.  (This allows the simplifier to unfold recursive
  1198 functional programs.)  To restore the old behaviour, declare
  1199 
  1200     Delcongs [if_weak_cong];
  1201 
  1202 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1203 complement;
  1204 
  1205 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1206 
  1207 * HOL/datatype: mutual_induct_tac no longer exists --
  1208   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1209 
  1210 * HOL/typedef: fixed type inference for representing set; type
  1211 arguments now have to occur explicitly on the rhs as type constraints;
  1212 
  1213 * ZF: The con_defs part of an inductive definition may no longer refer
  1214 to constants declared in the same theory;
  1215 
  1216 * HOL, ZF: the function mk_cases, generated by the inductive
  1217 definition package, has lost an argument.  To simplify its result, it
  1218 uses the default simpset instead of a supplied list of theorems.
  1219 
  1220 * HOL/List: the constructors of type list are now Nil and Cons;
  1221 
  1222 * Simplifier: the type of the infix ML functions
  1223         setSSolver addSSolver setSolver addSolver
  1224 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1225 for packaging solvers. A solver is created via
  1226         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1227 where the string argument is only a comment.
  1228 
  1229 
  1230 *** Proof tools ***
  1231 
  1232 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1233 decision procedure for linear arithmetic. Currently it is used for
  1234 types `nat', `int', and `real' in HOL (see below); it can, should and
  1235 will be instantiated for other types and logics as well.
  1236 
  1237 * The simplifier now accepts rewrite rules with flexible heads, eg
  1238      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1239   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1240   matching.
  1241 
  1242 
  1243 *** General ***
  1244 
  1245 * New Isabelle/Isar subsystem provides an alternative to traditional
  1246 tactical theorem proving; together with the ProofGeneral/isar user
  1247 interface it offers an interactive environment for developing human
  1248 readable proof documents (Isar == Intelligible semi-automated
  1249 reasoning); for further information see isatool doc isar-ref,
  1250 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1251 
  1252 * improved and simplified presentation of theories: better HTML markup
  1253 (including colors), graph views in several sizes; isatool usedir now
  1254 provides a proper interface for user theories (via -P option); actual
  1255 document preparation based on (PDF)LaTeX is available as well (for
  1256 new-style theories only); see isatool doc system for more information;
  1257 
  1258 * native support for Proof General, both for classic Isabelle and
  1259 Isabelle/Isar;
  1260 
  1261 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1262 using the graph browser tool;
  1263 
  1264 * Isabelle manuals now also available as PDF;
  1265 
  1266 * theory loader rewritten from scratch (may not be fully
  1267 bug-compatible); old loadpath variable has been replaced by show_path,
  1268 add_path, del_path, reset_path functions; new operations such as
  1269 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1270 isatool doc ref);
  1271 
  1272 * improved isatool install: option -k creates KDE application icon,
  1273 option -p DIR installs standalone binaries;
  1274 
  1275 * added ML_PLATFORM setting (useful for cross-platform installations);
  1276 more robust handling of platform specific ML images for SML/NJ;
  1277 
  1278 * the settings environment is now statically scoped, i.e. it is never
  1279 created again in sub-processes invoked from isabelle, isatool, or
  1280 Isabelle;
  1281 
  1282 * path element specification '~~' refers to '$ISABELLE_HOME';
  1283 
  1284 * in locales, the "assumes" and "defines" parts may be omitted if
  1285 empty;
  1286 
  1287 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1288 long arrows);
  1289 
  1290 * new print_mode "HTML";
  1291 
  1292 * new flag show_tags controls display of tags of theorems (which are
  1293 basically just comments that may be attached by some tools);
  1294 
  1295 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1296 mode and goal output format:
  1297 
  1298 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1299 244c244
  1300 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1301 ---
  1302 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1303 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1304 181c181
  1305 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1306 ---
  1307 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1308 
  1309 * function bind_thms stores lists of theorems (cf. bind_thm);
  1310 
  1311 * new shorthand tactics ftac, eatac, datac, fatac;
  1312 
  1313 * qed (and friends) now accept "" as result name; in that case the
  1314 theorem is not stored, but proper checks and presentation of the
  1315 result still apply;
  1316 
  1317 * theorem database now also indexes constants "Trueprop", "all",
  1318 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1319 
  1320 
  1321 *** HOL ***
  1322 
  1323 ** HOL arithmetic **
  1324 
  1325 * There are now decision procedures for linear arithmetic over nat and
  1326 int:
  1327 
  1328 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1329 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1330 are treated as atomic; subformulae not involving type `nat' or `int'
  1331 are ignored; quantified subformulae are ignored unless they are
  1332 positive universal or negative existential. The tactic has to be
  1333 invoked by hand and can be a little bit slow. In particular, the
  1334 running time is exponential in the number of occurrences of `min' and
  1335 `max', and `-' on `nat'.
  1336 
  1337 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1338 (negated) (in)equalities among the premises and the conclusion into
  1339 account (i.e. no compound formulae) and does not know about `min' and
  1340 `max', and `-' on `nat'. It is fast and is used automatically by the
  1341 simplifier.
  1342 
  1343 NB: At the moment, these decision procedures do not cope with mixed
  1344 nat/int formulae where the two parts interact, such as `m < n ==>
  1345 int(m) < int(n)'.
  1346 
  1347 * HOL/Numeral provides a generic theory of numerals (encoded
  1348 efficiently as bit strings); setup for types nat/int/real is in place;
  1349 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1350 int, existing theories and proof scripts may require a few additional
  1351 type constraints;
  1352 
  1353 * integer division and remainder can now be performed on constant
  1354 arguments;
  1355 
  1356 * many properties of integer multiplication, division and remainder
  1357 are now available;
  1358 
  1359 * An interface to the Stanford Validity Checker (SVC) is available through the
  1360 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1361 are proved automatically.  SVC must be installed separately, and its results
  1362 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1363 invocation of the underlying oracle).  For SVC see
  1364   http://verify.stanford.edu/SVC
  1365 
  1366 * IsaMakefile: the HOL-Real target now builds an actual image;
  1367 
  1368 
  1369 ** HOL misc **
  1370 
  1371 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1372 (in Isabelle/Isar) -- by Gertrud Bauer;
  1373 
  1374 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1375 analysis for assembly languages with subtypes;
  1376 
  1377 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1378 -- avoids syntactic ambiguities and treats state, transition, and
  1379 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1380 changed syntax and (many) tactics;
  1381 
  1382 * HOL/inductive: Now also handles more general introduction rules such
  1383   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1384   theorems are now maintained within the theory (maintained via the
  1385   "mono" attribute);
  1386 
  1387 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1388   (using function types) such as
  1389 
  1390   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1391 
  1392 * HOL/record: record_simproc (part of the default simpset) takes care
  1393 of selectors applied to updated records; record_split_tac is no longer
  1394 part of the default claset; update_defs may now be removed from the
  1395 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1396 
  1397   claset_ref () := claset() addSWrapper record_split_wrapper;
  1398   Delsimprocs [record_simproc]
  1399 
  1400 * HOL/typedef: fixed type inference for representing set; type
  1401 arguments now have to occur explicitly on the rhs as type constraints;
  1402 
  1403 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1404 names rather than an ML expression;
  1405 
  1406 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1407 supplied later.  Program schemes can be defined, such as
  1408     "While B C s = (if B s then While B C (C s) else s)"
  1409 where the well-founded relation can be chosen after B and C have been given.
  1410 
  1411 * HOL/List: the constructors of type list are now Nil and Cons;
  1412 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1413 course, ML tools referring to List.list.op # etc. have to be adapted;
  1414 
  1415 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1416 disabled by default; run isabelle with option -m HOL to get back to
  1417 the original Gordon/HOL-style output;
  1418 
  1419 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1420 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1421 
  1422 * HOL basic syntax simplified (more orthogonal): all variants of
  1423 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1424 Eps operator is provided as well: "SOME x. P[x]";
  1425 
  1426 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1427 
  1428 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1429 thus available for user theories;
  1430 
  1431 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1432 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1433 time;
  1434 
  1435 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1436 several times and then mp;
  1437 
  1438 
  1439 *** LK ***
  1440 
  1441 * the notation <<...>> is now available as a notation for sequences of
  1442 formulas;
  1443 
  1444 * the simplifier is now installed
  1445 
  1446 * the axiom system has been generalized (thanks to Soren Heilmann)
  1447 
  1448 * the classical reasoner now has a default rule database
  1449 
  1450 
  1451 *** ZF ***
  1452 
  1453 * new primrec section allows primitive recursive functions to be given
  1454 directly (as in HOL) over datatypes and the natural numbers;
  1455 
  1456 * new tactics induct_tac and exhaust_tac for induction (or case
  1457 analysis) over datatypes and the natural numbers;
  1458 
  1459 * the datatype declaration of type T now defines the recursor T_rec;
  1460 
  1461 * simplification automatically does freeness reasoning for datatype
  1462 constructors;
  1463 
  1464 * automatic type-inference, with AddTCs command to insert new
  1465 type-checking rules;
  1466 
  1467 * datatype introduction rules are now added as Safe Introduction rules
  1468 to the claset;
  1469 
  1470 * the syntax "if P then x else y" is now available in addition to
  1471 if(P,x,y);
  1472 
  1473 
  1474 *** Internal programming interfaces ***
  1475 
  1476 * tuned simplifier trace output; new flag debug_simp;
  1477 
  1478 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1479 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1480 
  1481 * AxClass.axclass_tac lost the theory argument;
  1482 
  1483 * tuned current_goals_markers semantics: begin / end goal avoids
  1484 printing empty lines;
  1485 
  1486 * removed prs and prs_fn hook, which was broken because it did not
  1487 include \n in its semantics, forcing writeln to add one
  1488 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1489 string -> unit if you really want to output text without newline;
  1490 
  1491 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1492 plain output, interface builders may have to enable 'isabelle_font'
  1493 mode to get Isabelle font glyphs as before;
  1494 
  1495 * refined token_translation interface; INCOMPATIBILITY: output length
  1496 now of type real instead of int;
  1497 
  1498 * theory loader actions may be traced via new ThyInfo.add_hook
  1499 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1500 your own database of information attached to *whole* theories -- as
  1501 opposed to intra-theory data slots offered via TheoryDataFun;
  1502 
  1503 * proper handling of dangling sort hypotheses (at last!);
  1504 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1505 extra sort hypotheses that can be witnessed from the type signature;
  1506 the force_strip_shyps flag is gone, any remaining shyps are simply
  1507 left in the theorem (with a warning issued by strip_shyps_warning);
  1508 
  1509 
  1510 
  1511 New in Isabelle98-1 (October 1998)
  1512 ----------------------------------
  1513 
  1514 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1515 
  1516 * several changes of automated proof tools;
  1517 
  1518 * HOL: major changes to the inductive and datatype packages, including
  1519 some minor incompatibilities of theory syntax;
  1520 
  1521 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1522 called `inj_on';
  1523 
  1524 * HOL: removed duplicate thms in Arith:
  1525   less_imp_add_less  should be replaced by  trans_less_add1
  1526   le_imp_add_le      should be replaced by  trans_le_add1
  1527 
  1528 * HOL: unary minus is now overloaded (new type constraints may be
  1529 required);
  1530 
  1531 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1532 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1533 now taken as an integer constant.
  1534 
  1535 * Pure: ML function 'theory_of' renamed to 'theory';
  1536 
  1537 
  1538 *** Proof tools ***
  1539 
  1540 * Simplifier:
  1541   1. Asm_full_simp_tac is now more aggressive.
  1542      1. It will sometimes reorient premises if that increases their power to
  1543         simplify.
  1544      2. It does no longer proceed strictly from left to right but may also
  1545         rotate premises to achieve further simplification.
  1546      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1547      old Asm_full_simp_tac in that it does not rotate premises.
  1548   2. The simplifier now knows a little bit about nat-arithmetic.
  1549 
  1550 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1551 allows for selected deletion of wrappers, by introduction of names for
  1552 wrapper functionals.  This implies that addbefore, addSbefore,
  1553 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1554 and that adding two tactics with the same name overwrites the first
  1555 one (emitting a warning).
  1556   type wrapper = (int -> tactic) -> (int -> tactic)
  1557   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1558   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1559   delWrapper, delSWrapper: claset *  string            -> claset
  1560   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1561 
  1562 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1563 semantics; addbefore now affects only the unsafe part of step_tac
  1564 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1565 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1566 by Force_tac;
  1567 
  1568 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1569 compWrapper; added safe wrapper (and access functions for it);
  1570 
  1571 * HOL/split_all_tac is now much faster and fails if there is nothing
  1572 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1573 and the names of the automatically generated variables have changed.
  1574 split_all_tac has moved within claset() from unsafe wrappers to safe
  1575 wrappers, which means that !!-bound variables are split much more
  1576 aggressively, and safe_tac and clarify_tac now split such variables.
  1577 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1578 Note: the same holds for record_split_tac, which does the job of
  1579 split_all_tac for record fields.
  1580 
  1581 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1582 permanently to the default simpset using Addsplits just like
  1583 Addsimps. They can be removed via Delsplits just like
  1584 Delsimps. Lower-case versions are also available.
  1585 
  1586 * HOL/Simplifier: The rule split_if is now part of the default
  1587 simpset. This means that the simplifier will eliminate all occurrences
  1588 of if-then-else in the conclusion of a goal. To prevent this, you can
  1589 either remove split_if completely from the default simpset by
  1590 `Delsplits [split_if]' or remove it in a specific call of the
  1591 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1592 other case splitting rules to/from the default simpset: every datatype
  1593 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1594 t is the name of the datatype).
  1595 
  1596 * Classical reasoner / Simplifier combination: new force_tac (and
  1597 derivatives Force_tac, force) combines rewriting and classical
  1598 reasoning (and whatever other tools) similarly to auto_tac, but is
  1599 aimed to solve the given subgoal completely.
  1600 
  1601 
  1602 *** General ***
  1603 
  1604 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1605 and `goalw': the theory is no longer needed as an explicit argument -
  1606 the current theory context is used; assumptions are no longer returned
  1607 at the ML-level unless one of them starts with ==> or !!; it is
  1608 recommended to convert to these new commands using isatool fixgoal
  1609 (backup your sources first!);
  1610 
  1611 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1612 the current theory context, and 'theory' to lookup stored theories;
  1613 
  1614 * new theory section 'locale' for declaring constants, assumptions and
  1615 definitions that have local scope;
  1616 
  1617 * new theory section 'nonterminals' for purely syntactic types;
  1618 
  1619 * new theory section 'setup' for generic ML setup functions
  1620 (e.g. package initialization);
  1621 
  1622 * the distribution now includes Isabelle icons: see
  1623 lib/logo/isabelle-{small,tiny}.xpm;
  1624 
  1625 * isatool install - install binaries with absolute references to
  1626 ISABELLE_HOME/bin;
  1627 
  1628 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1629 
  1630 * print mode 'emacs' reserved for Isamode;
  1631 
  1632 * support multiple print (ast) translations per constant name;
  1633 
  1634 * theorems involving oracles are now printed with a suffixed [!];
  1635 
  1636 
  1637 *** HOL ***
  1638 
  1639 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1640 
  1641 * HOL/inductive package reorganized and improved: now supports mutual
  1642 definitions such as
  1643 
  1644   inductive EVEN ODD
  1645     intrs
  1646       null "0 : EVEN"
  1647       oddI "n : EVEN ==> Suc n : ODD"
  1648       evenI "n : ODD ==> Suc n : EVEN"
  1649 
  1650 new theorem list "elims" contains an elimination rule for each of the
  1651 recursive sets; inductive definitions now handle disjunctive premises
  1652 correctly (also ZF);
  1653 
  1654 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1655 "mutual_induct" no longer exists - the induction rule is always
  1656 contained in "induct";
  1657 
  1658 
  1659 * HOL/datatype package re-implemented and greatly improved: now
  1660 supports mutually recursive datatypes such as
  1661 
  1662   datatype
  1663     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1664             | SUM ('a aexp) ('a aexp)
  1665             | DIFF ('a aexp) ('a aexp)
  1666             | NUM 'a
  1667   and
  1668     'a bexp = LESS ('a aexp) ('a aexp)
  1669             | AND ('a bexp) ('a bexp)
  1670             | OR ('a bexp) ('a bexp)
  1671 
  1672 as well as indirectly recursive datatypes such as
  1673 
  1674   datatype
  1675     ('a, 'b) term = Var 'a
  1676                   | App 'b ((('a, 'b) term) list)
  1677 
  1678 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1679 induction on mutually / indirectly recursive datatypes.
  1680 
  1681 Primrec equations are now stored in theory and can be accessed via
  1682 <function_name>.simps.
  1683 
  1684 INCOMPATIBILITIES:
  1685 
  1686   - Theories using datatypes must now have theory Datatype as an
  1687     ancestor.
  1688   - The specific <typename>.induct_tac no longer exists - use the
  1689     generic induct_tac instead.
  1690   - natE has been renamed to nat.exhaust - use exhaust_tac
  1691     instead of res_inst_tac ... natE. Note that the variable
  1692     names in nat.exhaust differ from the names in natE, this
  1693     may cause some "fragile" proofs to fail.
  1694   - The theorems split_<typename>_case and split_<typename>_case_asm
  1695     have been renamed to <typename>.split and <typename>.split_asm.
  1696   - Since default sorts of type variables are now handled correctly,
  1697     some datatype definitions may have to be annotated with explicit
  1698     sort constraints.
  1699   - Primrec definitions no longer require function name and type
  1700     of recursive argument.
  1701 
  1702 Consider using isatool fixdatatype to adapt your theories and proof
  1703 scripts to the new package (backup your sources first!).
  1704 
  1705 
  1706 * HOL/record package: considerably improved implementation; now
  1707 includes concrete syntax for record types, terms, updates; theorems
  1708 for surjective pairing and splitting !!-bound record variables; proof
  1709 support is as follows:
  1710 
  1711   1) standard conversions (selectors or updates applied to record
  1712 constructor terms) are part of the standard simpset;
  1713 
  1714   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1715 made part of standard simpset and claset via addIffs;
  1716 
  1717   3) a tactic for record field splitting (record_split_tac) is part of
  1718 the standard claset (addSWrapper);
  1719 
  1720 To get a better idea about these rules you may retrieve them via
  1721 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1722 the name of your record type.
  1723 
  1724 The split tactic 3) conceptually simplifies by the following rule:
  1725 
  1726   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1727 
  1728 Thus any record variable that is bound by meta-all will automatically
  1729 blow up into some record constructor term, consequently the
  1730 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1731 solve record problems automatically.
  1732 
  1733 
  1734 * reorganized the main HOL image: HOL/Integ and String loaded by
  1735 default; theory Main includes everything;
  1736 
  1737 * automatic simplification of integer sums and comparisons, using cancellation;
  1738 
  1739 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1740 
  1741 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1742 
  1743 * many new identities for unions, intersections, set difference, etc.;
  1744 
  1745 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1746 called split_if, split_split, split_sum_case and split_nat_case (to go
  1747 with add/delsplits);
  1748 
  1749 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1750 (?x::unit) = (); this is made part of the default simpset, which COULD
  1751 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1752 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1753 unit_abs_eta_conv is added in order to counter the effect of
  1754 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1755 %u.f();
  1756 
  1757 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1758 makes more sense);
  1759 
  1760 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1761   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1762   disjointness reasoning but breaking a few old proofs.
  1763 
  1764 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1765 to 'converse' from 'inverse' (for compatibility with ZF and some
  1766 literature);
  1767 
  1768 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1769 the well-founded relation;
  1770 
  1771 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1772     Compl A.  The "Compl" syntax remains available as input syntax for this
  1773     release ONLY.
  1774 
  1775 * HOL/Update: new theory of function updates:
  1776     f(a:=b) == %x. if x=a then b else f x
  1777 may also be iterated as in f(a:=b,c:=d,...);
  1778 
  1779 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1780 
  1781 * HOL/List:
  1782   - new function list_update written xs[i:=v] that updates the i-th
  1783     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1784   - new function `upt' written [i..j(] which generates the list
  1785     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1786     bound write [i..j], which is a shorthand for [i..j+1(].
  1787   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1788 
  1789 * HOL/Arith:
  1790   - removed 'pred' (predecessor) function;
  1791   - generalized some theorems about n-1;
  1792   - many new laws about "div" and "mod";
  1793   - new laws about greatest common divisors (see theory ex/Primes);
  1794 
  1795 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1796 instead of "inverse";
  1797 
  1798 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1799   of the multiset ordering;
  1800 
  1801 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1802   (not included by default);
  1803 
  1804 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1805 
  1806 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1807   programs, i.e. different program variables may have different types.
  1808 
  1809 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1810   [previously, this check worked only if the rewrite rule was unconditional]
  1811   Now rew can involve either definitions or equalities (either == or =).
  1812 
  1813 
  1814 *** ZF ***
  1815 
  1816 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1817   only the theorems proved on ZF.ML;
  1818 
  1819 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1820   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1821   disjointness reasoning but breaking a few old proofs.
  1822 
  1823 * ZF/Update: new theory of function updates
  1824     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1825   may also be iterated as in f(a:=b,c:=d,...);
  1826 
  1827 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1828 
  1829 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1830   [previously, this check worked only if the rewrite rule was unconditional]
  1831   Now rew can involve either definitions or equalities (either == or =).
  1832 
  1833 * case_tac provided for compatibility with HOL
  1834     (like the old excluded_middle_tac, but with subgoals swapped)
  1835 
  1836 
  1837 *** Internal programming interfaces ***
  1838 
  1839 * Pure: several new basic modules made available for general use, see
  1840 also src/Pure/README;
  1841 
  1842 * improved the theory data mechanism to support encapsulation (data
  1843 kind name replaced by private Object.kind, acting as authorization
  1844 key); new type-safe user interface via functor TheoryDataFun; generic
  1845 print_data function becomes basically useless;
  1846 
  1847 * removed global_names compatibility flag -- all theory declarations
  1848 are qualified by default;
  1849 
  1850 * module Pure/Syntax now offers quote / antiquote translation
  1851 functions (useful for Hoare logic etc. with implicit dependencies);
  1852 see HOL/ex/Antiquote for an example use;
  1853 
  1854 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1855 cterm -> thm;
  1856 
  1857 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1858 subgoal;
  1859 
  1860 * Display.print_goals function moved to Locale.print_goals;
  1861 
  1862 * standard print function for goals supports current_goals_markers
  1863 variable for marking begin of proof, end of proof, start of goal; the
  1864 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1865 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1866 for example;
  1867 
  1868 
  1869 
  1870 New in Isabelle98 (January 1998)
  1871 --------------------------------
  1872 
  1873 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1874 
  1875 * changed lexical syntax of terms / types: dots made part of long
  1876 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1877 
  1878 * simpset (and claset) reference variable replaced by functions
  1879 simpset / simpset_ref;
  1880 
  1881 * no longer supports theory aliases (via merge) and non-trivial
  1882 implicit merge of thms' signatures;
  1883 
  1884 * most internal names of constants changed due to qualified names;
  1885 
  1886 * changed Pure/Sequence interface (see Pure/seq.ML);
  1887 
  1888 
  1889 *** General Changes ***
  1890 
  1891 * hierachically structured name spaces (for consts, types, axms, thms
  1892 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1893 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1894 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1895 long_names for fully qualified output names; NOTE: ML programs
  1896 (special tactics, packages etc.) referring to internal names may have
  1897 to be adapted to cope with fully qualified names; in case of severe
  1898 backward campatibility problems try setting 'global_names' at compile
  1899 time to have enrything declared within a flat name space; one may also
  1900 fine tune name declarations in theories via the 'global' and 'local'
  1901 section;
  1902 
  1903 * reimplemented the implicit simpset and claset using the new anytype
  1904 data filed in signatures; references simpset:simpset ref etc. are
  1905 replaced by functions simpset:unit->simpset and
  1906 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1907 to patch your ML files accordingly;
  1908 
  1909 * HTML output now includes theory graph data for display with Java
  1910 applet or isatool browser; data generated automatically via isatool
  1911 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1912 
  1913 * defs may now be conditional; improved rewrite_goals_tac to handle
  1914 conditional equations;
  1915 
  1916 * defs now admits additional type arguments, using TYPE('a) syntax;
  1917 
  1918 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1919 creates a new theory node; implicit merge of thms' signatures is
  1920 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1921 transfer:theory->thm->thm in (rare) cases;
  1922 
  1923 * improved handling of draft signatures / theories; draft thms (and
  1924 ctyps, cterms) are automatically promoted to real ones;
  1925 
  1926 * slightly changed interfaces for oracles: admit many per theory, named
  1927 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1928 
  1929 * print_goals: optional output of const types (set show_consts and
  1930 show_types);
  1931 
  1932 * improved output of warnings (###) and errors (***);
  1933 
  1934 * subgoal_tac displays a warning if the new subgoal has type variables;
  1935 
  1936 * removed old README and Makefiles;
  1937 
  1938 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1939 
  1940 * removed obsolete init_pps and init_database;
  1941 
  1942 * deleted the obsolete tactical STATE, which was declared by
  1943     fun STATE tacfun st = tacfun st st;
  1944 
  1945 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1946 (which abbreviates $HOME);
  1947 
  1948 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1949 use isatool fixseq to adapt your ML programs (this works for fully
  1950 qualified references to the Sequence structure only!);
  1951 
  1952 * use_thy no longer requires writable current directory; it always
  1953 reloads .ML *and* .thy file, if either one is out of date;
  1954 
  1955 
  1956 *** Classical Reasoner ***
  1957 
  1958 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1959 tactics that use classical reasoning to simplify a subgoal without
  1960 splitting it into several subgoals;
  1961 
  1962 * Safe_tac: like safe_tac but uses the default claset;
  1963 
  1964 
  1965 *** Simplifier ***
  1966 
  1967 * added simplification meta rules:
  1968     (asm_)(full_)simplify: simpset -> thm -> thm;
  1969 
  1970 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1971 logics (again);
  1972 
  1973 * added prems argument to simplification procedures;
  1974 
  1975 * HOL, FOL, ZF: added infix function `addsplits':
  1976   instead of `<simpset> setloop (split_tac <thms>)'
  1977   you can simply write `<simpset> addsplits <thms>'
  1978 
  1979 
  1980 *** Syntax ***
  1981 
  1982 * TYPE('a) syntax for type reflection terms;
  1983 
  1984 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1985 
  1986 * pretty printer: changed order of mixfix annotation preference (again!);
  1987 
  1988 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1989 
  1990 
  1991 *** HOL ***
  1992 
  1993 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1994   with `addloop' of the simplifier to faciliate case splitting in premises.
  1995 
  1996 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1997 
  1998 * HOL/Auth: new protocol proofs including some for the Internet
  1999   protocol TLS;
  2000 
  2001 * HOL/Map: new theory of `maps' a la VDM;
  2002 
  2003 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2004 cancelling out common nat summands from =, <, <= (in)equalities, or
  2005 differences; simplification procedures nat_cancel_factor for
  2006 cancelling common factor from =, <, <= (in)equalities over natural
  2007 sums; nat_cancel contains both kinds of procedures, it is installed by
  2008 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2009 
  2010 * HOL/simplifier: terms of the form
  2011   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2012   are rewritten to
  2013   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2014   and those of the form
  2015   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2016   are rewritten to
  2017   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2018 
  2019 * HOL/datatype
  2020   Each datatype `t' now comes with a theorem `split_t_case' 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 
  2028   and a theorem `split_t_case_asm' of the form
  2029 
  2030   P(t_case f1 ... fn x) =
  2031     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2032         ...
  2033        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2034      )
  2035   which can be added to a simpset via `addsplits'. The existing theorems
  2036   expand_list_case and expand_option_case have been renamed to
  2037   split_list_case and split_option_case.
  2038 
  2039 * HOL/Arithmetic:
  2040   - `pred n' is automatically converted to `n-1'.
  2041     Users are strongly encouraged not to use `pred' any longer,
  2042     because it will disappear altogether at some point.
  2043   - Users are strongly encouraged to write "0 < n" rather than
  2044     "n ~= 0". Theorems and proof tools have been modified towards this
  2045     `standard'.
  2046 
  2047 * HOL/Lists:
  2048   the function "set_of_list" has been renamed "set" (and its theorems too);
  2049   the function "nth" now takes its arguments in the reverse order and
  2050   has acquired the infix notation "!" as in "xs!n".
  2051 
  2052 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2053 
  2054 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2055   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2056 
  2057 * HOL/record: extensible records with schematic structural subtyping
  2058 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2059 still lacks various theorems and concrete record syntax;
  2060 
  2061 
  2062 *** HOLCF ***
  2063 
  2064 * removed "axioms" and "generated by" sections;
  2065 
  2066 * replaced "ops" section by extended "consts" section, which is capable of
  2067   handling the continuous function space "->" directly;
  2068 
  2069 * domain package:
  2070   . proves theorems immediately and stores them in the theory,
  2071   . creates hierachical name space,
  2072   . now uses normal mixfix annotations (instead of cinfix...),
  2073   . minor changes to some names and values (for consistency),
  2074   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2075   . separator between mutual domain defs: changed "," to "and",
  2076   . improved handling of sort constraints;  now they have to
  2077     appear on the left-hand side of the equations only;
  2078 
  2079 * fixed LAM <x,y,zs>.b syntax;
  2080 
  2081 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2082 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2083 
  2084 
  2085 *** FOL and ZF ***
  2086 
  2087 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2088   with `addloop' of the simplifier to faciliate case splitting in premises.
  2089 
  2090 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2091 in HOL, they strip ALL and --> from proved theorems;
  2092 
  2093 
  2094 
  2095 New in Isabelle94-8 (May 1997)
  2096 ------------------------------
  2097 
  2098 *** General Changes ***
  2099 
  2100 * new utilities to build / run / maintain Isabelle etc. (in parts
  2101 still somewhat experimental); old Makefiles etc. still functional;
  2102 
  2103 * new 'Isabelle System Manual';
  2104 
  2105 * INSTALL text, together with ./configure and ./build scripts;
  2106 
  2107 * reimplemented type inference for greater efficiency, better error
  2108 messages and clean internal interface;
  2109 
  2110 * prlim command for dealing with lots of subgoals (an easier way of
  2111 setting goals_limit);
  2112 
  2113 
  2114 *** Syntax ***
  2115 
  2116 * supports alternative (named) syntax tables (parser and pretty
  2117 printer); internal interface is provided by add_modesyntax(_i);
  2118 
  2119 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2120 be used in conjunction with the Isabelle symbol font; uses the
  2121 "symbols" syntax table;
  2122 
  2123 * added token_translation interface (may translate name tokens in
  2124 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2125 the current print_mode); IMPORTANT: user print translation functions
  2126 are responsible for marking newly introduced bounds
  2127 (Syntax.mark_boundT);
  2128 
  2129 * token translations for modes "xterm" and "xterm_color" that display
  2130 names in bold, underline etc. or colors (which requires a color
  2131 version of xterm);
  2132 
  2133 * infixes may now be declared with names independent of their syntax;
  2134 
  2135 * added typed_print_translation (like print_translation, but may
  2136 access type of constant);
  2137 
  2138 
  2139 *** Classical Reasoner ***
  2140 
  2141 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2142 some limitations.  Blast_tac...
  2143   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2144   + ignores elimination rules that don't have the correct format
  2145         (the conclusion MUST be a formula variable)
  2146   + ignores types, which can make HOL proofs fail
  2147   + rules must not require higher-order unification, e.g. apply_type in ZF
  2148     [message "Function Var's argument not a bound variable" relates to this]
  2149   + its proof strategy is more general but can actually be slower
  2150 
  2151 * substitution with equality assumptions no longer permutes other
  2152 assumptions;
  2153 
  2154 * minor changes in semantics of addafter (now called addaltern); renamed
  2155 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2156 (and access functions for it);
  2157 
  2158 * improved combination of classical reasoner and simplifier:
  2159   + functions for handling clasimpsets
  2160   + improvement of addss: now the simplifier is called _after_ the
  2161     safe steps.
  2162   + safe variant of addss called addSss: uses safe simplifications
  2163     _during_ the safe steps. It is more complete as it allows multiple
  2164     instantiations of unknowns (e.g. with slow_tac).
  2165 
  2166 *** Simplifier ***
  2167 
  2168 * added interface for simplification procedures (functions that
  2169 produce *proven* rewrite rules on the fly, depending on current
  2170 redex);
  2171 
  2172 * ordering on terms as parameter (used for ordered rewriting);
  2173 
  2174 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2175 
  2176 * the solver is now split into a safe and an unsafe part.
  2177 This should be invisible for the normal user, except that the
  2178 functions setsolver and addsolver have been renamed to setSolver and
  2179 addSolver; added safe_asm_full_simp_tac;
  2180 
  2181 
  2182 *** HOL ***
  2183 
  2184 * a generic induction tactic `induct_tac' which works for all datatypes and
  2185 also for type `nat';
  2186 
  2187 * a generic case distinction tactic `exhaust_tac' which works for all
  2188 datatypes and also for type `nat';
  2189 
  2190 * each datatype comes with a function `size';
  2191 
  2192 * patterns in case expressions allow tuple patterns as arguments to
  2193 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2194 
  2195 * primrec now also works with type nat;
  2196 
  2197 * recdef: a new declaration form, allows general recursive functions to be
  2198 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2199 
  2200 * the constant for negation has been renamed from "not" to "Not" to
  2201 harmonize with FOL, ZF, LK, etc.;
  2202 
  2203 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2204 infinite lists;
  2205 
  2206 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2207 
  2208 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2209 problems in commutative rings, using axiomatic type classes for + and *;
  2210 
  2211 * more examples in HOL/MiniML and HOL/Auth;
  2212 
  2213 * more default rewrite rules for quantifiers, union/intersection;
  2214 
  2215 * a new constant `arbitrary == @x.False';
  2216 
  2217 * HOLCF/IOA replaces old HOL/IOA;
  2218 
  2219 * HOLCF changes: derived all rules and arities
  2220   + axiomatic type classes instead of classes
  2221   + typedef instead of faking type definitions
  2222   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2223   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2224   + eliminated the types void, one, tr
  2225   + use unit lift and bool lift (with translations) instead of one and tr
  2226   + eliminated blift from Lift3.thy (use Def instead of blift)
  2227   all eliminated rules are derived as theorems --> no visible changes ;
  2228 
  2229 
  2230 *** ZF ***
  2231 
  2232 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2233 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2234 as ZF_cs addSIs [equalityI];
  2235 
  2236 
  2237 
  2238 New in Isabelle94-7 (November 96)
  2239 ---------------------------------
  2240 
  2241 * allowing negative levels (as offsets) in prlev and choplev;
  2242 
  2243 * super-linear speedup for large simplifications;
  2244 
  2245 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2246 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2247 FAIL); can suppress it using the command Delsimps (ex_simps @
  2248 all_simps); De Morgan laws are also now included, by default;
  2249 
  2250 * improved printing of ==>  :  ~:
  2251 
  2252 * new object-logic "Sequents" adds linear logic, while replacing LK
  2253 and Modal (thanks to Sara Kalvala);
  2254 
  2255 * HOL/Auth: correctness proofs for authentication protocols;
  2256 
  2257 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2258 examples on HOL/Auth);
  2259 
  2260 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2261 the rewriter and classical reasoner simultaneously;
  2262 
  2263 * function uresult no longer returns theorems in "standard" format;
  2264 regain previous version by: val uresult = standard o uresult;
  2265 
  2266 
  2267 
  2268 New in Isabelle94-6
  2269 -------------------
  2270 
  2271 * oracles -- these establish an interface between Isabelle and trusted
  2272 external reasoners, which may deliver results as theorems;
  2273 
  2274 * proof objects (in particular record all uses of oracles);
  2275 
  2276 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2277 
  2278 * "constdefs" section in theory files;
  2279 
  2280 * "primrec" section (HOL) no longer requires names;
  2281 
  2282 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2283 
  2284 
  2285 
  2286 New in Isabelle94-5
  2287 -------------------
  2288 
  2289 * reduced space requirements;
  2290 
  2291 * automatic HTML generation from theories;
  2292 
  2293 * theory files no longer require "..." (quotes) around most types;
  2294 
  2295 * new examples, including two proofs of the Church-Rosser theorem;
  2296 
  2297 * non-curried (1994) version of HOL is no longer distributed;
  2298 
  2299 
  2300 
  2301 New in Isabelle94-4
  2302 -------------------
  2303 
  2304 * greatly reduced space requirements;
  2305 
  2306 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2307 
  2308 * searchable theorem database (see the section "Retrieving theorems" on
  2309 page 8 of the Reference Manual);
  2310 
  2311 * new examples, including Grabczewski's monumental case study of the
  2312 Axiom of Choice;
  2313 
  2314 * The previous version of HOL renamed to Old_HOL;
  2315 
  2316 * The new version of HOL (previously called CHOL) uses a curried syntax
  2317 for functions.  Application looks like f a b instead of f(a,b);
  2318 
  2319 * Mutually recursive inductive definitions finally work in HOL;
  2320 
  2321 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2322 translates to the operator "split";
  2323 
  2324 
  2325 
  2326 New in Isabelle94-3
  2327 -------------------
  2328 
  2329 * new infix operator, addss, allowing the classical reasoner to
  2330 perform simplification at each step of its search.  Example:
  2331         fast_tac (cs addss ss)
  2332 
  2333 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2334 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2335 look like (a,b) instead of <a,b>;
  2336 
  2337 * PLEASE NOTE: CHOL will eventually replace HOL!
  2338 
  2339 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2340 It translates to the operator "split".  A new theory of integers is available;
  2341 
  2342 * In ZF, integer numerals now denote two's-complement binary integers.
  2343 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2344 
  2345 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2346 of the Axiom of Choice;
  2347 
  2348 
  2349 
  2350 New in Isabelle94-2
  2351 -------------------
  2352 
  2353 * Significantly faster resolution;
  2354 
  2355 * the different sections in a .thy file can now be mixed and repeated
  2356 freely;
  2357 
  2358 * Database of theorems for FOL, HOL and ZF.  New
  2359 commands including qed, qed_goal and bind_thm store theorems in the database.
  2360 
  2361 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2362 a given theory (thms_of), or find out what theory a theorem was proved in
  2363 (theory_of_thm);
  2364 
  2365 * Bugs fixed in the inductive definition and datatype packages;
  2366 
  2367 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2368 and HOL_dup_cs obsolete;
  2369 
  2370 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2371 have been removed;
  2372 
  2373 * Simpler definition of function space in ZF;
  2374 
  2375 * new results about cardinal and ordinal arithmetic in ZF;
  2376 
  2377 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2378 types;
  2379 
  2380 
  2381 $Id$