NEWS
author paulson
Thu Mar 20 17:15:16 2003 +0100 (2003-03-20)
changeset 13872 601514e63534
parent 13868 01b516b64233
child 13881 f63e2a057fd4
permissions -rw-r--r--
Gauss, UNITY, ZF
     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   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
    48 
    49 * Pure: The main goal of the proof state is no longer shown by default, only
    50 the subgoals. This behaviour is controlled by a new flag.
    51    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
    52 (ML: Proof.show_main_goal).
    53 
    54 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
    55 rules whose conclusion matches subgoal 1:
    56       PG menu: Isabelle/Isar -> Show me -> matching rules
    57 The rules are ordered by how closely they match the subgoal.
    58 In particular, rules that solve a subgoal outright are displayed first
    59 (or rather last, the way they are printed).
    60 (ML: ProofGeneral.print_intros())
    61 
    62 * Pure: New flag trace_unify_fail causes unification to print
    63 diagnostic information (PG: in trace buffer) when it fails. This is
    64 useful for figuring out why single step proofs like rule, erule or
    65 assumption failed.
    66 
    67 * Pure: Locale specifications now produce predicate definitions
    68 according to the body of text (covering assumptions modulo local
    69 definitions); predicate "loc_axioms" covers newly introduced text,
    70 while "loc" is cumulative wrt. all included locale expressions; the
    71 latter view is presented only on export into the global theory
    72 context; potential INCOMPATIBILITY, use "(open)" option to fall back
    73 on the old view without predicates;
    74 
    75 * Pure: predefined locales "var" and "struct" are useful for sharing
    76 parameters (as in CASL, for example); just specify something like
    77 ``var x + var y + struct M'' as import;
    78 
    79 * Pure: improved thms_containing: proper indexing of facts instead of
    80 raw theorems; check validity of results wrt. current name space;
    81 include local facts of proof configuration (also covers active
    82 locales), cover fixed variables in index; may use "_" in term
    83 specification; an optional limit for the number of printed facts may
    84 be given (the default is 40);
    85 
    86 * Pure: disallow duplicate fact bindings within new-style theory files
    87 (batch-mode only);
    88 
    89 * Provers: improved induct method: assumptions introduced by case
    90 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
    91 the goal statement); "foo" still refers to all facts collectively;
    92 
    93 * Provers: the function blast.overloaded has been removed: all constants
    94 are regarded as potentially overloaded, which improves robustness in exchange
    95 for slight decrease in efficiency;
    96 
    97 * Provers/linorder: New generic prover for transitivity reasoning over
    98 linear orders.  Note: this prover is not efficient!
    99 
   100 * Isar: preview of problems to finish 'show' now produce an error
   101 rather than just a warning (in interactive mode);
   102 
   103 
   104 *** HOL ***
   105 
   106 * New tactic "trans_tac" and method "trans" instantiate
   107 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   108 "<=", "<" and "="). 
   109 
   110 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main 
   111 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   112 
   113 * 'typedef' command has new option "open" to suppress the set
   114 definition;
   115 
   116 * functions Min and Max on finite sets have been introduced (theory
   117 Finite_Set);
   118 
   119 * attribute [symmetric] now works for relations as well; it turns
   120 (x,y) : R^-1 into (y,x) : R, and vice versa;
   121 
   122 * arith(_tac) now produces a counter example if it cannot prove a theorem.
   123   In ProofGeneral the counter example appears in the trace buffer.
   124 
   125 * arith(_tac) does now know about div k and mod k where k is a numeral
   126 of type nat or int. It can solve simple goals like
   127 
   128   "0 < n ==> n div 2 < (n::nat)"
   129 
   130 but fails if divisibility plays a role like in
   131 
   132   "n div 2 + (n+1) div 2 = (n::nat)"
   133 
   134 * simp's arithmetic capabilities have been enhanced a bit: it now
   135 takes ~= in premises into account (by performing a case split);
   136 
   137 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   138 are distributed over a sum of terms;
   139 
   140 * induct over a !!-quantified statement (say !!x1..xn):
   141   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   142 
   143 * Real/HahnBanach: updated and adapted to locales;
   144 
   145 * GroupTheory: converted to Isar theories, using locales with implicit
   146 structures.  Also a new, experimental summation operator for abelian groups;
   147 
   148 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad, Gray and
   149 Kramer);
   150 
   151 * UNITY: added the Meier-Sanders theory of progress sets;
   152 
   153 
   154 *** ZF ***
   155 
   156 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   157 universe, etc.);
   158 
   159 * Main ZF: virtually all theories converted to new-style format;
   160 
   161 
   162 *** ML ***
   163 
   164 * Pure: Tactic.prove provides sane interface for internal proofs;
   165 omits the infamous "standard" operation, so this is more appropriate
   166 than prove_goalw_cterm in many situations (e.g. in simprocs);
   167 
   168 * Pure: improved error reporting of simprocs;
   169 
   170 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   171 up simprocs;
   172 
   173 
   174 
   175 New in Isabelle2002 (March 2002)
   176 --------------------------------
   177 
   178 *** Document preparation ***
   179 
   180 * greatly simplified document preparation setup, including more
   181 graceful interpretation of isatool usedir -i/-d/-D options, and more
   182 instructive isatool mkdir; users should basically be able to get
   183 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   184 users may run a separate document processing stage manually like this:
   185 "isatool usedir -D output HOL Test && isatool document Test/output";
   186 
   187 * theory dependency graph may now be incorporated into documents;
   188 isatool usedir -g true will produce session_graph.eps/.pdf for use
   189 with \includegraphics of LaTeX;
   190 
   191 * proper spacing of consecutive markup elements, especially text
   192 blocks after section headings;
   193 
   194 * support bold style (for single symbols only), input syntax is like
   195 this: "\<^bold>\<alpha>" or "\<^bold>A";
   196 
   197 * \<bullet> is now output as bold \cdot by default, which looks much
   198 better in printed text;
   199 
   200 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   201 note that these symbols are currently unavailable in Proof General /
   202 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   203 
   204 * isatool latex no longer depends on changed TEXINPUTS, instead
   205 isatool document copies the Isabelle style files to the target
   206 location;
   207 
   208 
   209 *** Isar ***
   210 
   211 * Pure/Provers: improved proof by cases and induction;
   212   - 'case' command admits impromptu naming of parameters (such as
   213     "case (Suc n)");
   214   - 'induct' method divinates rule instantiation from the inductive
   215     claim; no longer requires excessive ?P bindings for proper
   216     instantiation of cases;
   217   - 'induct' method properly enumerates all possibilities of set/type
   218     rules; as a consequence facts may be also passed through *type*
   219     rules without further ado;
   220   - 'induct' method now derives symbolic cases from the *rulified*
   221     rule (before it used to rulify cases stemming from the internal
   222     atomized version); this means that the context of a non-atomic
   223     statement becomes is included in the hypothesis, avoiding the
   224     slightly cumbersome show "PROP ?case" form;
   225   - 'induct' may now use elim-style induction rules without chaining
   226     facts, using ``missing'' premises from the goal state; this allows
   227     rules stemming from inductive sets to be applied in unstructured
   228     scripts, while still benefitting from proper handling of non-atomic
   229     statements; NB: major inductive premises need to be put first, all
   230     the rest of the goal is passed through the induction;
   231   - 'induct' proper support for mutual induction involving non-atomic
   232     rule statements (uses the new concept of simultaneous goals, see
   233     below);
   234   - append all possible rule selections, but only use the first
   235     success (no backtracking);
   236   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   237   - undeclared rule case names default to numbers 1, 2, 3, ...;
   238   - added 'print_induct_rules' (covered by help item in recent Proof
   239     General versions);
   240   - moved induct/cases attributes to Pure, methods to Provers;
   241   - generic method setup instantiated for FOL and HOL;
   242 
   243 * Pure: support multiple simultaneous goal statements, for example
   244 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   245 meta-level mechanism, this acts as if several individual goals had
   246 been stated separately; in particular common proof methods need to be
   247 repeated in order to cover all claims; note that a single elimination
   248 step is *not* sufficient to establish the two conjunctions, so this
   249 fails:
   250 
   251   assume "A & B" then have A and B ..   (*".." fails*)
   252 
   253 better use "obtain" in situations as above; alternative refer to
   254 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   255 
   256 * Pure: proper integration with ``locales''; unlike the original
   257 version by Florian Kammüller, Isar locales package high-level proof
   258 contexts rather than raw logical ones (e.g. we admit to include
   259 attributes everywhere); operations on locales include merge and
   260 rename; support for implicit arguments (``structures''); simultaneous
   261 type-inference over imports and text; see also HOL/ex/Locales.thy for
   262 some examples;
   263 
   264 * Pure: the following commands have been ``localized'', supporting a
   265 target locale specification "(in name)": 'lemma', 'theorem',
   266 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   267 stored both within the locale and at the theory level (exported and
   268 qualified by the locale name);
   269 
   270 * Pure: theory goals may now be specified in ``long'' form, with
   271 ad-hoc contexts consisting of arbitrary locale elements. for example
   272 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   273 definitions may be given, too); the result is a meta-level rule with
   274 the context elements being discharged in the obvious way;
   275 
   276 * Pure: new proof command 'using' allows to augment currently used
   277 facts after a goal statement ('using' is syntactically analogous to
   278 'apply', but acts on the goal's facts only); this allows chained facts
   279 to be separated into parts given before and after a claim, as in
   280 ``from a and b have C using d and e <proof>'';
   281 
   282 * Pure: renamed "antecedent" case to "rule_context";
   283 
   284 * Pure: new 'judgment' command records explicit information about the
   285 object-logic embedding (used by several tools internally); no longer
   286 use hard-wired "Trueprop";
   287 
   288 * Pure: added 'corollary' command;
   289 
   290 * Pure: fixed 'token_translation' command;
   291 
   292 * Pure: removed obsolete 'exported' attribute;
   293 
   294 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   295 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   296 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   297 
   298 * Pure: method 'atomize' presents local goal premises as object-level
   299 statements (atomic meta-level propositions); setup controlled via
   300 rewrite rules declarations of 'atomize' attribute; example
   301 application: 'induct' method with proper rule statements in improper
   302 proof *scripts*;
   303 
   304 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   305 now consider the syntactic context of assumptions, giving a better
   306 chance to get type-inference of the arguments right (this is
   307 especially important for locales);
   308 
   309 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   310 mode;
   311 
   312 * Pure/obtain: the formal conclusion "thesis", being marked as
   313 ``internal'', may no longer be reference directly in the text;
   314 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   315 situations;
   316 
   317 * Pure: generic 'sym' attribute which declares a rule both as pure
   318 'elim?' and for the 'symmetric' operation;
   319 
   320 * Pure: marginal comments ``--'' may now occur just anywhere in the
   321 text; the fixed correlation with particular command syntax has been
   322 discontinued;
   323 
   324 * Pure: new method 'rules' is particularly well-suited for proof
   325 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   326 but often produces more compact proof terms with less detours;
   327 
   328 * Pure/Provers/classical: simplified integration with pure rule
   329 attributes and methods; the classical "intro?/elim?/dest?"
   330 declarations coincide with the pure ones; the "rule" method no longer
   331 includes classically swapped intros; "intro" and "elim" methods no
   332 longer pick rules from the context; also got rid of ML declarations
   333 AddXIs/AddXEs/AddXDs; all of this has some potential for
   334 INCOMPATIBILITY;
   335 
   336 * Provers/classical: attribute 'swapped' produces classical inversions
   337 of introduction rules;
   338 
   339 * Provers/simplifier: 'simplified' attribute may refer to explicit
   340 rules instead of full simplifier context; 'iff' attribute handles
   341 conditional rules;
   342 
   343 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   344 
   345 * HOL: 'recdef' now fails on unfinished automated proofs, use
   346 "(permissive)" option to recover old behavior;
   347 
   348 * HOL: 'inductive' no longer features separate (collective) attributes
   349 for 'intros' (was found too confusing);
   350 
   351 * HOL: properly declared induction rules less_induct and
   352 wf_induct_rule;
   353 
   354 
   355 *** HOL ***
   356 
   357 * HOL: moved over to sane numeral syntax; the new policy is as
   358 follows:
   359 
   360   - 0 and 1 are polymorphic constants, which are defined on any
   361   numeric type (nat, int, real etc.);
   362 
   363   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   364   binary representation internally;
   365 
   366   - type nat has special constructor Suc, and generally prefers Suc 0
   367   over 1::nat and Suc (Suc 0) over 2::nat;
   368 
   369 This change may cause significant problems of INCOMPATIBILITY; here
   370 are some hints on converting existing sources:
   371 
   372   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   373   entities, so expressions involving "-" (unary or binary minus) need
   374   to be spaced properly;
   375 
   376   - existing occurrences of "1" may need to be constraint "1::nat" or
   377   even replaced by Suc 0; similar for old "2";
   378 
   379   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   380 
   381   - remove all special provisions on numerals in proofs;
   382 
   383 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   384 representation (depends on bin_arith_simps in the default context);
   385 
   386 * HOL: symbolic syntax for x^2 (numeral 2);
   387 
   388 * HOL: the class of all HOL types is now called "type" rather than
   389 "term"; INCOMPATIBILITY, need to adapt references to this type class
   390 in axclass/classes, instance/arities, and (usually rare) occurrences
   391 in typings (of consts etc.); internally the class is called
   392 "HOL.type", ML programs should refer to HOLogic.typeS;
   393 
   394 * HOL/record package improvements:
   395   - new derived operations "fields" to build a partial record section,
   396     "extend" to promote a fixed record to a record scheme, and
   397     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   398     declared as simp by default;
   399   - shared operations ("more", "fields", etc.) now need to be always
   400     qualified) --- potential INCOMPATIBILITY;
   401   - removed "make_scheme" operations (use "make" with "extend") --
   402     INCOMPATIBILITY;
   403   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   404   - provides cases/induct rules for use with corresponding Isar
   405     methods (for concrete records, record schemes, concrete more
   406     parts, and schematic more parts -- in that order);
   407   - internal definitions directly based on a light-weight abstract
   408     theory of product types over typedef rather than datatype;
   409 
   410 * HOL: generic code generator for generating executable ML code from
   411 specifications; specific support for HOL constructs such as inductive
   412 datatypes and sets, as well as recursive functions; can be invoked
   413 via 'generate_code' theory section;
   414 
   415 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   416 
   417 * HOL: consolidated and renamed several theories.  In particular:
   418 	Ord.thy has been absorbed into HOL.thy
   419 	String.thy has been absorbed into List.thy
   420  
   421 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   422 (beware of argument permutation!);
   423 
   424 * HOL: linorder_less_split superseded by linorder_cases;
   425 
   426 * HOL/List: "nodups" renamed to "distinct";
   427 
   428 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   429 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   430   - Ex_def has changed, now need to use some_eq_ex
   431 
   432 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   433 in this (rare) case use:
   434 
   435   delSWrapper "split_all_tac"
   436   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   437 
   438 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   439 MAY FAIL;
   440 
   441 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   442 Isabelle's type classes, ^ on functions and relations has too general
   443 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   444 necessary to attach explicit type constraints;
   445 
   446 * HOL/Relation: the prefix name of the infix "O" has been changed from
   447 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   448 renamed accordingly (eg "compI" -> "rel_compI").
   449 
   450 * HOL: syntax translations now work properly with numerals and records
   451 expressions;
   452 
   453 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   454 of "lam" -- INCOMPATIBILITY;
   455 
   456 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   457 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   458 renamed "Product_Type.unit";
   459 
   460 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   461 
   462 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   463 the "cases" method);
   464 
   465 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   466 Florian Kammüller);
   467 
   468 * HOL/IMP: updated and converted to new-style theory format; several
   469 parts turned into readable document, with proper Isar proof texts and
   470 some explanations (by Gerwin Klein);
   471 
   472 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   473 
   474 * HOL-Hyperreal is now a logic image;
   475 
   476 
   477 *** HOLCF ***
   478 
   479 * Isar: consts/constdefs supports mixfix syntax for continuous
   480 operations;
   481 
   482 * Isar: domain package adapted to new-style theory format, e.g. see
   483 HOLCF/ex/Dnat.thy;
   484 
   485 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   486 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   487 lift.induct_tac, always use UU instead of Undef;
   488 
   489 * HOLCF/IMP: updated and converted to new-style theory;
   490 
   491 
   492 *** ZF ***
   493 
   494 * Isar: proper integration of logic-specific tools and packages,
   495 including theory commands '(co)inductive', '(co)datatype',
   496 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   497 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   498 
   499 * theory Main no longer includes AC; for the Axiom of Choice, base
   500 your theory on Main_ZFC;
   501 
   502 * the integer library now covers quotients and remainders, with many
   503 laws relating division to addition, multiplication, etc.;
   504 
   505 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   506 typeless version of the formalism;
   507 
   508 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   509 format;
   510 
   511 * ZF/Induct: new directory for examples of inductive definitions,
   512 including theory Multiset for multiset orderings; converted to
   513 new-style theory format;
   514 
   515 * ZF: many new theorems about lists, ordinals, etc.;
   516 
   517 
   518 *** General ***
   519 
   520 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   521 variable proof controls level of detail: 0 = no proofs (only oracle
   522 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   523 also ref manual for further ML interfaces;
   524 
   525 * Pure/axclass: removed obsolete ML interface
   526 goal_subclass/goal_arity;
   527 
   528 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   529 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   530 separate tokens, so expressions involving minus need to be spaced
   531 properly;
   532 
   533 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   534 rather than "infixl" or "infixr";
   535 
   536 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   537 sort constraint specifications in type inference; e.g. "x::_::foo"
   538 ensures that the type of "x" is of sort "foo" (but not necessarily a
   539 type variable);
   540 
   541 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   542 control output of nested => (types); the default behavior is
   543 "type_brackets";
   544 
   545 * Pure/syntax: builtin parse translation for "_constify" turns valued
   546 tokens into AST constants;
   547 
   548 * Pure/syntax: prefer later declarations of translations and print
   549 translation functions; potential INCOMPATIBILITY: need to reverse
   550 multiple declarations for same syntax element constant;
   551 
   552 * Pure/show_hyps reset by default (in accordance to existing Isar
   553 practice);
   554 
   555 * Provers/classical: renamed addaltern to addafter, addSaltern to
   556 addSafter;
   557 
   558 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   559 as well;
   560 
   561 * system: tested support for MacOS X; should be able to get Isabelle +
   562 Proof General to work in a plain Terminal after installing Poly/ML
   563 (e.g. from the Isabelle distribution area) and GNU bash alone
   564 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   565 support requires further installations, e.g. from
   566 http://fink.sourceforge.net/);
   567 
   568 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   569 
   570 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   571 of 40 MB), cf. ML_OPTIONS;
   572 
   573 * system: Proof General keywords specification is now part of the
   574 Isabelle distribution (see etc/isar-keywords.el);
   575 
   576 * system: support for persistent Proof General sessions (refrain from
   577 outdating all loaded theories on startup); user may create writable
   578 logic images like this: ``isabelle -q HOL Test'';
   579 
   580 * system: smart selection of Isabelle process versus Isabelle
   581 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   582 run both "isabelle" and "Isabelle" even if file names are badly
   583 damaged (executable inspects the case of the first letter of its own
   584 name); added separate "isabelle-process" and "isabelle-interface";
   585 
   586 * system: refrain from any attempt at filtering input streams; no
   587 longer support ``8bit'' encoding of old isabelle font, instead proper
   588 iso-latin characters may now be used; the related isatools
   589 "symbolinput" and "nonascii" have disappeared as well;
   590 
   591 * system: removed old "xterm" interface (the print modes "xterm" and
   592 "xterm_color" are still available for direct use in a suitable
   593 terminal);
   594 
   595 
   596 
   597 New in Isabelle99-2 (February 2001)
   598 -----------------------------------
   599 
   600 *** Overview of INCOMPATIBILITIES ***
   601 
   602 * HOL: please note that theories in the Library and elsewhere often use the
   603 new-style (Isar) format; to refer to their theorems in an ML script you must
   604 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   605 
   606 * HOL: inductive package no longer splits induction rule aggressively,
   607 but only as far as specified by the introductions given; the old
   608 format may be recovered via ML function complete_split_rule or attribute
   609 'split_rule (complete)';
   610 
   611 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   612 gfp_Tarski to gfp_unfold;
   613 
   614 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   615 
   616 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   617 relation); infix "^^" has been renamed "``"; infix "``" has been
   618 renamed "`"; "univalent" has been renamed "single_valued";
   619 
   620 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   621 operation;
   622 
   623 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   624 
   625 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   626 
   627 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   628 consequence, it is no longer monotonic wrt. the local goal context
   629 (which is now passed through the inductive cases);
   630 
   631 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   632 \<gg> to \<ggreater>;
   633 
   634 
   635 *** Document preparation ***
   636 
   637 * \isabellestyle{NAME} selects version of Isabelle output (currently
   638 available: are "it" for near math-mode best-style output, "sl" for
   639 slanted text style, and "tt" for plain type-writer; if no
   640 \isabellestyle command is given, output is according to slanted
   641 type-writer);
   642 
   643 * support sub/super scripts (for single symbols only), input syntax is
   644 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   645 
   646 * some more standard symbols; see Appendix A of the system manual for
   647 the complete list of symbols defined in isabellesym.sty;
   648 
   649 * improved isabelle style files; more abstract symbol implementation
   650 (should now use \isamath{...} and \isatext{...} in custom symbol
   651 definitions);
   652 
   653 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   654 state; Note that presentation of goal states does not conform to
   655 actual human-readable proof documents.  Please do not include goal
   656 states into document output unless you really know what you are doing!
   657 
   658 * proper indentation of antiquoted output with proportional LaTeX
   659 fonts;
   660 
   661 * no_document ML operator temporarily disables LaTeX document
   662 generation;
   663 
   664 * isatool unsymbolize tunes sources for plain ASCII communication;
   665 
   666 
   667 *** Isar ***
   668 
   669 * Pure: Isar now suffers initial goal statements to contain unbound
   670 schematic variables (this does not conform to actual readable proof
   671 documents, due to unpredictable outcome and non-compositional proof
   672 checking); users who know what they are doing may use schematic goals
   673 for Prolog-style synthesis of proven results;
   674 
   675 * Pure: assumption method (an implicit finishing) now handles actual
   676 rules as well;
   677 
   678 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   679 initial goal, declare "that" only as Pure intro (only for single
   680 steps); the "that" rule assumption may now be involved in implicit
   681 finishing, thus ".." becomes a feasible for trivial obtains;
   682 
   683 * Pure: default proof step now includes 'intro_classes'; thus trivial
   684 instance proofs may be performed by "..";
   685 
   686 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   687 statements as well;
   688 
   689 * Pure: more robust selection of calculational rules;
   690 
   691 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   692 rule (as well as the assumption rule);
   693 
   694 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   695 lemmas, using the graph browser tool;
   696 
   697 * Pure: predict failure of "show" in interactive mode;
   698 
   699 * Pure: 'thms_containing' now takes actual terms as arguments;
   700 
   701 * HOL: improved method 'induct' --- now handles non-atomic goals
   702 (potential INCOMPATIBILITY); tuned error handling;
   703 
   704 * HOL: cases and induct rules now provide explicit hints about the
   705 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   706 any remaining facts are inserted into the goal verbatim;
   707 
   708 * HOL: local contexts (aka cases) may now contain term bindings as
   709 well; the 'cases' and 'induct' methods new provide a ?case binding for
   710 the result to be shown in each case;
   711 
   712 * HOL: added 'recdef_tc' command;
   713 
   714 * isatool convert assists in eliminating legacy ML scripts;
   715 
   716 
   717 *** HOL ***
   718 
   719 * HOL/Library: a collection of generic theories to be used together
   720 with main HOL; the theory loader path already includes this directory
   721 by default; the following existing theories have been moved here:
   722 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   723 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   724 
   725 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   726 modelling and verification task performed in Isabelle/HOL +
   727 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   728 
   729 * HOL/Algebra: special summation operator SUM no longer exists, it has
   730 been replaced by setsum; infix 'assoc' now has priority 50 (like
   731 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   732 'domain', this makes the theory consistent with mathematical
   733 literature;
   734 
   735 * HOL basics: added overloaded operations "inverse" and "divide"
   736 (infix "/"), syntax for generic "abs" operation, generic summation
   737 operator \<Sum>;
   738 
   739 * HOL/typedef: simplified package, provide more useful rules (see also
   740 HOL/subset.thy);
   741 
   742 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   743 now expressed as a proper nested rule (old-style tactic scripts may
   744 require atomize_strip_tac to cope with non-atomic premises);
   745 
   746 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   747 to "split_conv" (old name still available for compatibility);
   748 
   749 * HOL: improved concrete syntax for strings (e.g. allows translation
   750 rules with string literals);
   751 
   752 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   753  and Fleuriot's mechanization of analysis, including the transcendental
   754  functions for the reals;
   755 
   756 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   757 
   758 
   759 *** CTT ***
   760 
   761 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   762 "lam" is displayed as TWO lambda-symbols
   763 
   764 * CTT: theory Main now available, containing everything (that is, Bool
   765 and Arith);
   766 
   767 
   768 *** General ***
   769 
   770 * Pure: the Simplifier has been implemented properly as a derived rule
   771 outside of the actual kernel (at last!); the overall performance
   772 penalty in practical applications is about 50%, while reliability of
   773 the Isabelle inference kernel has been greatly improved;
   774 
   775 * print modes "brackets" and "no_brackets" control output of nested =>
   776 (types) and ==> (props); the default behaviour is "brackets";
   777 
   778 * Provers: fast_tac (and friends) now handle actual object-logic rules
   779 as assumptions as well;
   780 
   781 * system: support Poly/ML 4.0;
   782 
   783 * system: isatool install handles KDE version 1 or 2;
   784 
   785 
   786 
   787 New in Isabelle99-1 (October 2000)
   788 ----------------------------------
   789 
   790 *** Overview of INCOMPATIBILITIES ***
   791 
   792 * HOL: simplification of natural numbers is much changed; to partly
   793 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   794 issue the following ML commands:
   795 
   796   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   797   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   798 
   799 * HOL: simplification no longer dives into case-expressions; this is
   800 controlled by "t.weak_case_cong" for each datatype t;
   801 
   802 * HOL: nat_less_induct renamed to less_induct;
   803 
   804 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   805 fixsome to patch .thy and .ML sources automatically;
   806 
   807   select_equality  -> some_equality
   808   select_eq_Ex     -> some_eq_ex
   809   selectI2EX       -> someI2_ex
   810   selectI2         -> someI2
   811   selectI          -> someI
   812   select1_equality -> some1_equality
   813   Eps_sym_eq       -> some_sym_eq_trivial
   814   Eps_eq           -> some_eq_trivial
   815 
   816 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   817 
   818 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   819 instead);
   820 
   821 * HOL: the recursion equations generated by 'recdef' are now called
   822 f.simps instead of f.rules;
   823 
   824 * HOL: qed_spec_mp now also handles bounded ALL as well;
   825 
   826 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   827 sometimes be needed;
   828 
   829 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   830 
   831 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   832 
   833 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   834 product is now "<*>" instead of "Times"; the lexicographic product is
   835 now "<*lex*>" instead of "**";
   836 
   837 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   838 of main HOL, but was unused); better use HOL's datatype package;
   839 
   840 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   841 the old syntax may be recovered as follows:
   842 
   843   syntax (symbols)
   844     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   845       (infixl "\\<oplus>" 100)
   846 
   847 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   848 
   849 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   850 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   851 internally;
   852 
   853 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   854 changed from A/r to A//r;
   855 
   856 * ZF: new treatment of arithmetic (nat & int) may break some old
   857 proofs;
   858 
   859 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   860 rulify -> rule_format, elimify -> elim_format, ...);
   861 
   862 * Isar/Provers: intro/elim/dest attributes changed; renamed
   863 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   864 should have to change intro!! to intro? only); replaced "delrule" by
   865 "rule del";
   866 
   867 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   868 
   869 * Provers: strengthened force_tac by using new first_best_tac;
   870 
   871 * LaTeX document preparation: several changes of isabelle.sty (see
   872 lib/texinputs);
   873 
   874 
   875 *** Document preparation ***
   876 
   877 * formal comments (text blocks etc.) in new-style theories may now
   878 contain antiquotations of thm/prop/term/typ/text to be presented
   879 according to latex print mode; concrete syntax is like this:
   880 @{term[show_types] "f(x) = a + x"};
   881 
   882 * isatool mkdir provides easy setup of Isabelle session directories,
   883 including proper document sources;
   884 
   885 * generated LaTeX sources are now deleted after successful run
   886 (isatool document -c); may retain a copy somewhere else via -D option
   887 of isatool usedir;
   888 
   889 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   890 style files, achieving self-contained LaTeX sources and simplifying
   891 LaTeX debugging;
   892 
   893 * old-style theories now produce (crude) LaTeX output as well;
   894 
   895 * browser info session directories are now self-contained (may be put
   896 on WWW server seperately); improved graphs of nested sessions; removed
   897 graph for 'all sessions';
   898 
   899 * several improvements in isabelle style files; \isabellestyle{it}
   900 produces fake math mode output; \isamarkupheader is now \section by
   901 default; see lib/texinputs/isabelle.sty etc.;
   902 
   903 
   904 *** Isar ***
   905 
   906 * Isar/Pure: local results and corresponding term bindings are now
   907 subject to Hindley-Milner polymorphism (similar to ML); this
   908 accommodates incremental type-inference very nicely;
   909 
   910 * Isar/Pure: new derived language element 'obtain' supports
   911 generalized existence reasoning;
   912 
   913 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   914 support accumulation of results, without applying any rules yet;
   915 useful to collect intermediate results without explicit name
   916 references, and for use with transitivity rules with more than 2
   917 premises;
   918 
   919 * Isar/Pure: scalable support for case-analysis type proofs: new
   920 'case' language element refers to local contexts symbolically, as
   921 produced by certain proof methods; internally, case names are attached
   922 to theorems as "tags";
   923 
   924 * Isar/Pure: theory command 'hide' removes declarations from
   925 class/type/const name spaces;
   926 
   927 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   928 indicate potential overloading;
   929 
   930 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   931 
   932 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   933 "{a,b,c}" instead of {a,b,c};
   934 
   935 * Isar/Pure now provides its own version of intro/elim/dest
   936 attributes; useful for building new logics, but beware of confusion
   937 with the version in Provers/classical;
   938 
   939 * Isar/Pure: the local context of (non-atomic) goals is provided via
   940 case name 'antecedent';
   941 
   942 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   943 to the current context is now done automatically);
   944 
   945 * Isar/Pure: theory command 'method_setup' provides a simple interface
   946 for definining proof methods in ML;
   947 
   948 * Isar/Provers: intro/elim/dest attributes changed; renamed
   949 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   950 most cases, one should have to change intro!! to intro? only);
   951 replaced "delrule" by "rule del";
   952 
   953 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   954 'symmetric' attribute (the latter supercedes [RS sym]);
   955 
   956 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   957 method modifier); 'simp' method: 'only:' modifier removes loopers as
   958 well (including splits);
   959 
   960 * Isar/Provers: Simplifier and Classical methods now support all kind
   961 of modifiers used in the past, including 'cong', 'iff', etc.
   962 
   963 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   964 of Simplifier and Classical reasoner);
   965 
   966 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   967 now support named cases; major packages (inductive, datatype, primrec,
   968 recdef) support case names and properly name parameters;
   969 
   970 * Isar/HOL: new transitivity rules for substitution in inequalities --
   971 monotonicity conditions are extracted to be proven at end of
   972 calculations;
   973 
   974 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   975 method anyway;
   976 
   977 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   978 split_if split_if_asm; datatype package provides theorems foo.splits =
   979 foo.split foo.split_asm for each datatype;
   980 
   981 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   982 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   983 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   984 use "(cases (simplified))" method in proper proof texts);
   985 
   986 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   987 
   988 * Isar: names of theorems etc. may be natural numbers as well;
   989 
   990 * Isar: 'pr' command: optional arguments for goals_limit and
   991 ProofContext.prems_limit; no longer prints theory contexts, but only
   992 proof states;
   993 
   994 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   995 additional print modes to be specified; e.g. "pr(latex)" will print
   996 proof state according to the Isabelle LaTeX style;
   997 
   998 * Isar: improved support for emulating tactic scripts, including proof
   999 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1000 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1001 (for HOL datatypes);
  1002 
  1003 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1004 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1005 'proof method scripts' have to be in depth-first order;
  1006 
  1007 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1008 
  1009 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1010 should instead use individual commands for printing items
  1011 (print_commands, print_methods etc.);
  1012 
  1013 * Isar: added 'nothing' --- the empty list of theorems;
  1014 
  1015 
  1016 *** HOL ***
  1017 
  1018 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1019 corresponding virtual machine and a specification of its bytecode
  1020 verifier and a lightweight bytecode verifier, including proofs of
  1021 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1022 Cornelia Pusch (see also the homepage of project Bali at
  1023 http://isabelle.in.tum.de/Bali/);
  1024 
  1025 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1026 Clemens Ballarin;
  1027 
  1028 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1029 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1030 Rasmussen;
  1031 
  1032 * HOL/Lattice: fundamental concepts of lattice theory and order
  1033 structures, including duals, properties of bounds versus algebraic
  1034 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1035 Theorem for complete lattices etc.; may also serve as a demonstration
  1036 for abstract algebraic reasoning using axiomatic type classes, and
  1037 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1038 
  1039 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1040 von Oheimb;
  1041 
  1042 * HOL/IMPP: extension of IMP with local variables and mutually
  1043 recursive procedures, by David von Oheimb;
  1044 
  1045 * HOL/Lambda: converted into new-style theory and document;
  1046 
  1047 * HOL/ex/Multiquote: example of multiple nested quotations and
  1048 anti-quotations -- basically a generalized version of de-Bruijn
  1049 representation; very useful in avoiding lifting of operations;
  1050 
  1051 * HOL/record: added general record equality rule to simpset; fixed
  1052 select-update simplification procedure to handle extended records as
  1053 well; admit "r" as field name;
  1054 
  1055 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1056 other numeric types and also as the identity of groups, rings, etc.;
  1057 
  1058 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1059 Types nat and int belong to this axclass;
  1060 
  1061 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1062    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1063    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1064   two terms #m*u and #n*u are replaced by #(m+n)*u
  1065     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1066   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1067     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1068 
  1069 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1070 powerful prover for predicate logic but knows nothing of clasets; see
  1071 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1072 
  1073 * HOL: new version of "case_tac" subsumes both boolean case split and
  1074 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1075 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1076 
  1077 * HOL: simplification no longer dives into case-expressions: only the
  1078 selector expression is simplified, but not the remaining arms; to
  1079 enable full simplification of case-expressions for datatype t, you may
  1080 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1081 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1082 
  1083 * HOL/recdef: the recursion equations generated by 'recdef' for
  1084 function 'f' are now called f.simps instead of f.rules; if all
  1085 termination conditions are proved automatically, these simplification
  1086 rules are added to the simpset, as in primrec; rules may be named
  1087 individually as well, resulting in a separate list of theorems for
  1088 each equation;
  1089 
  1090 * HOL/While is a new theory that provides a while-combinator. It
  1091 permits the definition of tail-recursive functions without the
  1092 provision of a termination measure. The latter is necessary once the
  1093 invariant proof rule for while is applied.
  1094 
  1095 * HOL: new (overloaded) notation for the set of elements below/above
  1096 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1097 
  1098 * HOL: theorems impI, allI, ballI bound as "strip";
  1099 
  1100 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1101 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1102 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1103 
  1104 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1105 
  1106 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1107 main HOL, but was unused);
  1108 
  1109 * HOL: fewer consts declared as global (e.g. have to refer to
  1110 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1111 
  1112 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1113 in case of overlap with user translations (e.g. judgements over
  1114 tuples); (note that the underlying logical represenation is still
  1115 bogus);
  1116 
  1117 
  1118 *** ZF ***
  1119 
  1120 * ZF: simplification automatically cancels common terms in arithmetic
  1121 expressions over nat and int;
  1122 
  1123 * ZF: new treatment of nat to minimize type-checking: all operators
  1124 coerce their operands to a natural number using the function natify,
  1125 making the algebraic laws unconditional;
  1126 
  1127 * ZF: as above, for int: operators coerce their operands to an integer
  1128 using the function intify;
  1129 
  1130 * ZF: the integer library now contains many of the usual laws for the
  1131 orderings, including $<=, and monotonicity laws for $+ and $*;
  1132 
  1133 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1134 simplification;
  1135 
  1136 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1137 to the simplifier and classical reasoner simultaneously;
  1138 
  1139 
  1140 *** General ***
  1141 
  1142 * Provers: blast_tac now handles actual object-logic rules as
  1143 assumptions; note that auto_tac uses blast_tac internally as well;
  1144 
  1145 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1146 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1147 
  1148 * Provers: delrules now handles destruct rules as well (no longer need
  1149 explicit make_elim);
  1150 
  1151 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1152   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1153 use instead the strong form,
  1154   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1155 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1156 from destruct-rules;
  1157 
  1158 * Provers: Simplifier.easy_setup provides a fast path to basic
  1159 Simplifier setup for new object-logics;
  1160 
  1161 * Pure: AST translation rules no longer require constant head on LHS;
  1162 
  1163 * Pure: improved name spaces: ambiguous output is qualified; support
  1164 for hiding of names;
  1165 
  1166 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1167 XSYMBOL_HOME; no longer need to do manual configuration in most
  1168 situations;
  1169 
  1170 * system: compression of ML heaps images may now be controlled via -c
  1171 option of isabelle and isatool usedir (currently only observed by
  1172 Poly/ML);
  1173 
  1174 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1175 useful for remote X11);
  1176 
  1177 * system: provide TAGS file for Isabelle sources;
  1178 
  1179 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1180 order;
  1181 
  1182 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1183 timing flag supersedes proof_timing and Toplevel.trace;
  1184 
  1185 * ML: new combinators |>> and |>>> for incremental transformations
  1186 with secondary results (e.g. certain theory extensions):
  1187 
  1188 * ML: PureThy.add_defs gets additional argument to indicate potential
  1189 overloading (usually false);
  1190 
  1191 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1192 results;
  1193 
  1194 
  1195 
  1196 New in Isabelle99 (October 1999)
  1197 --------------------------------
  1198 
  1199 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1200 
  1201 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1202 are no longer simplified.  (This allows the simplifier to unfold recursive
  1203 functional programs.)  To restore the old behaviour, declare
  1204 
  1205     Delcongs [if_weak_cong];
  1206 
  1207 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1208 complement;
  1209 
  1210 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1211 
  1212 * HOL/datatype: mutual_induct_tac no longer exists --
  1213   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1214 
  1215 * HOL/typedef: fixed type inference for representing set; type
  1216 arguments now have to occur explicitly on the rhs as type constraints;
  1217 
  1218 * ZF: The con_defs part of an inductive definition may no longer refer
  1219 to constants declared in the same theory;
  1220 
  1221 * HOL, ZF: the function mk_cases, generated by the inductive
  1222 definition package, has lost an argument.  To simplify its result, it
  1223 uses the default simpset instead of a supplied list of theorems.
  1224 
  1225 * HOL/List: the constructors of type list are now Nil and Cons;
  1226 
  1227 * Simplifier: the type of the infix ML functions
  1228         setSSolver addSSolver setSolver addSolver
  1229 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1230 for packaging solvers. A solver is created via
  1231         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1232 where the string argument is only a comment.
  1233 
  1234 
  1235 *** Proof tools ***
  1236 
  1237 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1238 decision procedure for linear arithmetic. Currently it is used for
  1239 types `nat', `int', and `real' in HOL (see below); it can, should and
  1240 will be instantiated for other types and logics as well.
  1241 
  1242 * The simplifier now accepts rewrite rules with flexible heads, eg
  1243      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1244   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1245   matching.
  1246 
  1247 
  1248 *** General ***
  1249 
  1250 * New Isabelle/Isar subsystem provides an alternative to traditional
  1251 tactical theorem proving; together with the ProofGeneral/isar user
  1252 interface it offers an interactive environment for developing human
  1253 readable proof documents (Isar == Intelligible semi-automated
  1254 reasoning); for further information see isatool doc isar-ref,
  1255 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1256 
  1257 * improved and simplified presentation of theories: better HTML markup
  1258 (including colors), graph views in several sizes; isatool usedir now
  1259 provides a proper interface for user theories (via -P option); actual
  1260 document preparation based on (PDF)LaTeX is available as well (for
  1261 new-style theories only); see isatool doc system for more information;
  1262 
  1263 * native support for Proof General, both for classic Isabelle and
  1264 Isabelle/Isar;
  1265 
  1266 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1267 using the graph browser tool;
  1268 
  1269 * Isabelle manuals now also available as PDF;
  1270 
  1271 * theory loader rewritten from scratch (may not be fully
  1272 bug-compatible); old loadpath variable has been replaced by show_path,
  1273 add_path, del_path, reset_path functions; new operations such as
  1274 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1275 isatool doc ref);
  1276 
  1277 * improved isatool install: option -k creates KDE application icon,
  1278 option -p DIR installs standalone binaries;
  1279 
  1280 * added ML_PLATFORM setting (useful for cross-platform installations);
  1281 more robust handling of platform specific ML images for SML/NJ;
  1282 
  1283 * the settings environment is now statically scoped, i.e. it is never
  1284 created again in sub-processes invoked from isabelle, isatool, or
  1285 Isabelle;
  1286 
  1287 * path element specification '~~' refers to '$ISABELLE_HOME';
  1288 
  1289 * in locales, the "assumes" and "defines" parts may be omitted if
  1290 empty;
  1291 
  1292 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1293 long arrows);
  1294 
  1295 * new print_mode "HTML";
  1296 
  1297 * new flag show_tags controls display of tags of theorems (which are
  1298 basically just comments that may be attached by some tools);
  1299 
  1300 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1301 mode and goal output format:
  1302 
  1303 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1304 244c244
  1305 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1306 ---
  1307 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1308 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1309 181c181
  1310 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1311 ---
  1312 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1313 
  1314 * function bind_thms stores lists of theorems (cf. bind_thm);
  1315 
  1316 * new shorthand tactics ftac, eatac, datac, fatac;
  1317 
  1318 * qed (and friends) now accept "" as result name; in that case the
  1319 theorem is not stored, but proper checks and presentation of the
  1320 result still apply;
  1321 
  1322 * theorem database now also indexes constants "Trueprop", "all",
  1323 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1324 
  1325 
  1326 *** HOL ***
  1327 
  1328 ** HOL arithmetic **
  1329 
  1330 * There are now decision procedures for linear arithmetic over nat and
  1331 int:
  1332 
  1333 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1334 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1335 are treated as atomic; subformulae not involving type `nat' or `int'
  1336 are ignored; quantified subformulae are ignored unless they are
  1337 positive universal or negative existential. The tactic has to be
  1338 invoked by hand and can be a little bit slow. In particular, the
  1339 running time is exponential in the number of occurrences of `min' and
  1340 `max', and `-' on `nat'.
  1341 
  1342 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1343 (negated) (in)equalities among the premises and the conclusion into
  1344 account (i.e. no compound formulae) and does not know about `min' and
  1345 `max', and `-' on `nat'. It is fast and is used automatically by the
  1346 simplifier.
  1347 
  1348 NB: At the moment, these decision procedures do not cope with mixed
  1349 nat/int formulae where the two parts interact, such as `m < n ==>
  1350 int(m) < int(n)'.
  1351 
  1352 * HOL/Numeral provides a generic theory of numerals (encoded
  1353 efficiently as bit strings); setup for types nat/int/real is in place;
  1354 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1355 int, existing theories and proof scripts may require a few additional
  1356 type constraints;
  1357 
  1358 * integer division and remainder can now be performed on constant
  1359 arguments;
  1360 
  1361 * many properties of integer multiplication, division and remainder
  1362 are now available;
  1363 
  1364 * An interface to the Stanford Validity Checker (SVC) is available through the
  1365 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1366 are proved automatically.  SVC must be installed separately, and its results
  1367 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1368 invocation of the underlying oracle).  For SVC see
  1369   http://verify.stanford.edu/SVC
  1370 
  1371 * IsaMakefile: the HOL-Real target now builds an actual image;
  1372 
  1373 
  1374 ** HOL misc **
  1375 
  1376 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1377 (in Isabelle/Isar) -- by Gertrud Bauer;
  1378 
  1379 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1380 analysis for assembly languages with subtypes;
  1381 
  1382 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1383 -- avoids syntactic ambiguities and treats state, transition, and
  1384 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1385 changed syntax and (many) tactics;
  1386 
  1387 * HOL/inductive: Now also handles more general introduction rules such
  1388   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1389   theorems are now maintained within the theory (maintained via the
  1390   "mono" attribute);
  1391 
  1392 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1393   (using function types) such as
  1394 
  1395   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1396 
  1397 * HOL/record: record_simproc (part of the default simpset) takes care
  1398 of selectors applied to updated records; record_split_tac is no longer
  1399 part of the default claset; update_defs may now be removed from the
  1400 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1401 
  1402   claset_ref () := claset() addSWrapper record_split_wrapper;
  1403   Delsimprocs [record_simproc]
  1404 
  1405 * HOL/typedef: fixed type inference for representing set; type
  1406 arguments now have to occur explicitly on the rhs as type constraints;
  1407 
  1408 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1409 names rather than an ML expression;
  1410 
  1411 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1412 supplied later.  Program schemes can be defined, such as
  1413     "While B C s = (if B s then While B C (C s) else s)"
  1414 where the well-founded relation can be chosen after B and C have been given.
  1415 
  1416 * HOL/List: the constructors of type list are now Nil and Cons;
  1417 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1418 course, ML tools referring to List.list.op # etc. have to be adapted;
  1419 
  1420 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1421 disabled by default; run isabelle with option -m HOL to get back to
  1422 the original Gordon/HOL-style output;
  1423 
  1424 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1425 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1426 
  1427 * HOL basic syntax simplified (more orthogonal): all variants of
  1428 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1429 Eps operator is provided as well: "SOME x. P[x]";
  1430 
  1431 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1432 
  1433 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1434 thus available for user theories;
  1435 
  1436 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1437 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1438 time;
  1439 
  1440 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1441 several times and then mp;
  1442 
  1443 
  1444 *** LK ***
  1445 
  1446 * the notation <<...>> is now available as a notation for sequences of
  1447 formulas;
  1448 
  1449 * the simplifier is now installed
  1450 
  1451 * the axiom system has been generalized (thanks to Soren Heilmann)
  1452 
  1453 * the classical reasoner now has a default rule database
  1454 
  1455 
  1456 *** ZF ***
  1457 
  1458 * new primrec section allows primitive recursive functions to be given
  1459 directly (as in HOL) over datatypes and the natural numbers;
  1460 
  1461 * new tactics induct_tac and exhaust_tac for induction (or case
  1462 analysis) over datatypes and the natural numbers;
  1463 
  1464 * the datatype declaration of type T now defines the recursor T_rec;
  1465 
  1466 * simplification automatically does freeness reasoning for datatype
  1467 constructors;
  1468 
  1469 * automatic type-inference, with AddTCs command to insert new
  1470 type-checking rules;
  1471 
  1472 * datatype introduction rules are now added as Safe Introduction rules
  1473 to the claset;
  1474 
  1475 * the syntax "if P then x else y" is now available in addition to
  1476 if(P,x,y);
  1477 
  1478 
  1479 *** Internal programming interfaces ***
  1480 
  1481 * tuned simplifier trace output; new flag debug_simp;
  1482 
  1483 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1484 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1485 
  1486 * AxClass.axclass_tac lost the theory argument;
  1487 
  1488 * tuned current_goals_markers semantics: begin / end goal avoids
  1489 printing empty lines;
  1490 
  1491 * removed prs and prs_fn hook, which was broken because it did not
  1492 include \n in its semantics, forcing writeln to add one
  1493 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1494 string -> unit if you really want to output text without newline;
  1495 
  1496 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1497 plain output, interface builders may have to enable 'isabelle_font'
  1498 mode to get Isabelle font glyphs as before;
  1499 
  1500 * refined token_translation interface; INCOMPATIBILITY: output length
  1501 now of type real instead of int;
  1502 
  1503 * theory loader actions may be traced via new ThyInfo.add_hook
  1504 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1505 your own database of information attached to *whole* theories -- as
  1506 opposed to intra-theory data slots offered via TheoryDataFun;
  1507 
  1508 * proper handling of dangling sort hypotheses (at last!);
  1509 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1510 extra sort hypotheses that can be witnessed from the type signature;
  1511 the force_strip_shyps flag is gone, any remaining shyps are simply
  1512 left in the theorem (with a warning issued by strip_shyps_warning);
  1513 
  1514 
  1515 
  1516 New in Isabelle98-1 (October 1998)
  1517 ----------------------------------
  1518 
  1519 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1520 
  1521 * several changes of automated proof tools;
  1522 
  1523 * HOL: major changes to the inductive and datatype packages, including
  1524 some minor incompatibilities of theory syntax;
  1525 
  1526 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1527 called `inj_on';
  1528 
  1529 * HOL: removed duplicate thms in Arith:
  1530   less_imp_add_less  should be replaced by  trans_less_add1
  1531   le_imp_add_le      should be replaced by  trans_le_add1
  1532 
  1533 * HOL: unary minus is now overloaded (new type constraints may be
  1534 required);
  1535 
  1536 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1537 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1538 now taken as an integer constant.
  1539 
  1540 * Pure: ML function 'theory_of' renamed to 'theory';
  1541 
  1542 
  1543 *** Proof tools ***
  1544 
  1545 * Simplifier:
  1546   1. Asm_full_simp_tac is now more aggressive.
  1547      1. It will sometimes reorient premises if that increases their power to
  1548         simplify.
  1549      2. It does no longer proceed strictly from left to right but may also
  1550         rotate premises to achieve further simplification.
  1551      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1552      old Asm_full_simp_tac in that it does not rotate premises.
  1553   2. The simplifier now knows a little bit about nat-arithmetic.
  1554 
  1555 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1556 allows for selected deletion of wrappers, by introduction of names for
  1557 wrapper functionals.  This implies that addbefore, addSbefore,
  1558 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1559 and that adding two tactics with the same name overwrites the first
  1560 one (emitting a warning).
  1561   type wrapper = (int -> tactic) -> (int -> tactic)
  1562   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1563   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1564   delWrapper, delSWrapper: claset *  string            -> claset
  1565   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1566 
  1567 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1568 semantics; addbefore now affects only the unsafe part of step_tac
  1569 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1570 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1571 by Force_tac;
  1572 
  1573 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1574 compWrapper; added safe wrapper (and access functions for it);
  1575 
  1576 * HOL/split_all_tac is now much faster and fails if there is nothing
  1577 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1578 and the names of the automatically generated variables have changed.
  1579 split_all_tac has moved within claset() from unsafe wrappers to safe
  1580 wrappers, which means that !!-bound variables are split much more
  1581 aggressively, and safe_tac and clarify_tac now split such variables.
  1582 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1583 Note: the same holds for record_split_tac, which does the job of
  1584 split_all_tac for record fields.
  1585 
  1586 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1587 permanently to the default simpset using Addsplits just like
  1588 Addsimps. They can be removed via Delsplits just like
  1589 Delsimps. Lower-case versions are also available.
  1590 
  1591 * HOL/Simplifier: The rule split_if is now part of the default
  1592 simpset. This means that the simplifier will eliminate all occurrences
  1593 of if-then-else in the conclusion of a goal. To prevent this, you can
  1594 either remove split_if completely from the default simpset by
  1595 `Delsplits [split_if]' or remove it in a specific call of the
  1596 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1597 other case splitting rules to/from the default simpset: every datatype
  1598 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1599 t is the name of the datatype).
  1600 
  1601 * Classical reasoner / Simplifier combination: new force_tac (and
  1602 derivatives Force_tac, force) combines rewriting and classical
  1603 reasoning (and whatever other tools) similarly to auto_tac, but is
  1604 aimed to solve the given subgoal completely.
  1605 
  1606 
  1607 *** General ***
  1608 
  1609 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1610 and `goalw': the theory is no longer needed as an explicit argument -
  1611 the current theory context is used; assumptions are no longer returned
  1612 at the ML-level unless one of them starts with ==> or !!; it is
  1613 recommended to convert to these new commands using isatool fixgoal
  1614 (backup your sources first!);
  1615 
  1616 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1617 the current theory context, and 'theory' to lookup stored theories;
  1618 
  1619 * new theory section 'locale' for declaring constants, assumptions and
  1620 definitions that have local scope;
  1621 
  1622 * new theory section 'nonterminals' for purely syntactic types;
  1623 
  1624 * new theory section 'setup' for generic ML setup functions
  1625 (e.g. package initialization);
  1626 
  1627 * the distribution now includes Isabelle icons: see
  1628 lib/logo/isabelle-{small,tiny}.xpm;
  1629 
  1630 * isatool install - install binaries with absolute references to
  1631 ISABELLE_HOME/bin;
  1632 
  1633 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1634 
  1635 * print mode 'emacs' reserved for Isamode;
  1636 
  1637 * support multiple print (ast) translations per constant name;
  1638 
  1639 * theorems involving oracles are now printed with a suffixed [!];
  1640 
  1641 
  1642 *** HOL ***
  1643 
  1644 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1645 
  1646 * HOL/inductive package reorganized and improved: now supports mutual
  1647 definitions such as
  1648 
  1649   inductive EVEN ODD
  1650     intrs
  1651       null "0 : EVEN"
  1652       oddI "n : EVEN ==> Suc n : ODD"
  1653       evenI "n : ODD ==> Suc n : EVEN"
  1654 
  1655 new theorem list "elims" contains an elimination rule for each of the
  1656 recursive sets; inductive definitions now handle disjunctive premises
  1657 correctly (also ZF);
  1658 
  1659 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1660 "mutual_induct" no longer exists - the induction rule is always
  1661 contained in "induct";
  1662 
  1663 
  1664 * HOL/datatype package re-implemented and greatly improved: now
  1665 supports mutually recursive datatypes such as
  1666 
  1667   datatype
  1668     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1669             | SUM ('a aexp) ('a aexp)
  1670             | DIFF ('a aexp) ('a aexp)
  1671             | NUM 'a
  1672   and
  1673     'a bexp = LESS ('a aexp) ('a aexp)
  1674             | AND ('a bexp) ('a bexp)
  1675             | OR ('a bexp) ('a bexp)
  1676 
  1677 as well as indirectly recursive datatypes such as
  1678 
  1679   datatype
  1680     ('a, 'b) term = Var 'a
  1681                   | App 'b ((('a, 'b) term) list)
  1682 
  1683 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1684 induction on mutually / indirectly recursive datatypes.
  1685 
  1686 Primrec equations are now stored in theory and can be accessed via
  1687 <function_name>.simps.
  1688 
  1689 INCOMPATIBILITIES:
  1690 
  1691   - Theories using datatypes must now have theory Datatype as an
  1692     ancestor.
  1693   - The specific <typename>.induct_tac no longer exists - use the
  1694     generic induct_tac instead.
  1695   - natE has been renamed to nat.exhaust - use exhaust_tac
  1696     instead of res_inst_tac ... natE. Note that the variable
  1697     names in nat.exhaust differ from the names in natE, this
  1698     may cause some "fragile" proofs to fail.
  1699   - The theorems split_<typename>_case and split_<typename>_case_asm
  1700     have been renamed to <typename>.split and <typename>.split_asm.
  1701   - Since default sorts of type variables are now handled correctly,
  1702     some datatype definitions may have to be annotated with explicit
  1703     sort constraints.
  1704   - Primrec definitions no longer require function name and type
  1705     of recursive argument.
  1706 
  1707 Consider using isatool fixdatatype to adapt your theories and proof
  1708 scripts to the new package (backup your sources first!).
  1709 
  1710 
  1711 * HOL/record package: considerably improved implementation; now
  1712 includes concrete syntax for record types, terms, updates; theorems
  1713 for surjective pairing and splitting !!-bound record variables; proof
  1714 support is as follows:
  1715 
  1716   1) standard conversions (selectors or updates applied to record
  1717 constructor terms) are part of the standard simpset;
  1718 
  1719   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1720 made part of standard simpset and claset via addIffs;
  1721 
  1722   3) a tactic for record field splitting (record_split_tac) is part of
  1723 the standard claset (addSWrapper);
  1724 
  1725 To get a better idea about these rules you may retrieve them via
  1726 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1727 the name of your record type.
  1728 
  1729 The split tactic 3) conceptually simplifies by the following rule:
  1730 
  1731   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1732 
  1733 Thus any record variable that is bound by meta-all will automatically
  1734 blow up into some record constructor term, consequently the
  1735 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1736 solve record problems automatically.
  1737 
  1738 
  1739 * reorganized the main HOL image: HOL/Integ and String loaded by
  1740 default; theory Main includes everything;
  1741 
  1742 * automatic simplification of integer sums and comparisons, using cancellation;
  1743 
  1744 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1745 
  1746 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1747 
  1748 * many new identities for unions, intersections, set difference, etc.;
  1749 
  1750 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1751 called split_if, split_split, split_sum_case and split_nat_case (to go
  1752 with add/delsplits);
  1753 
  1754 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1755 (?x::unit) = (); this is made part of the default simpset, which COULD
  1756 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1757 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1758 unit_abs_eta_conv is added in order to counter the effect of
  1759 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1760 %u.f();
  1761 
  1762 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1763 makes more sense);
  1764 
  1765 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1766   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1767   disjointness reasoning but breaking a few old proofs.
  1768 
  1769 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1770 to 'converse' from 'inverse' (for compatibility with ZF and some
  1771 literature);
  1772 
  1773 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1774 the well-founded relation;
  1775 
  1776 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1777     Compl A.  The "Compl" syntax remains available as input syntax for this
  1778     release ONLY.
  1779 
  1780 * HOL/Update: new theory of function updates:
  1781     f(a:=b) == %x. if x=a then b else f x
  1782 may also be iterated as in f(a:=b,c:=d,...);
  1783 
  1784 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1785 
  1786 * HOL/List:
  1787   - new function list_update written xs[i:=v] that updates the i-th
  1788     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1789   - new function `upt' written [i..j(] which generates the list
  1790     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1791     bound write [i..j], which is a shorthand for [i..j+1(].
  1792   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1793 
  1794 * HOL/Arith:
  1795   - removed 'pred' (predecessor) function;
  1796   - generalized some theorems about n-1;
  1797   - many new laws about "div" and "mod";
  1798   - new laws about greatest common divisors (see theory ex/Primes);
  1799 
  1800 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1801 instead of "inverse";
  1802 
  1803 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1804   of the multiset ordering;
  1805 
  1806 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1807   (not included by default);
  1808 
  1809 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1810 
  1811 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1812   programs, i.e. different program variables may have different types.
  1813 
  1814 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1815   [previously, this check worked only if the rewrite rule was unconditional]
  1816   Now rew can involve either definitions or equalities (either == or =).
  1817 
  1818 
  1819 *** ZF ***
  1820 
  1821 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1822   only the theorems proved on ZF.ML;
  1823 
  1824 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1825   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1826   disjointness reasoning but breaking a few old proofs.
  1827 
  1828 * ZF/Update: new theory of function updates
  1829     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1830   may also be iterated as in f(a:=b,c:=d,...);
  1831 
  1832 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1833 
  1834 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1835   [previously, this check worked only if the rewrite rule was unconditional]
  1836   Now rew can involve either definitions or equalities (either == or =).
  1837 
  1838 * case_tac provided for compatibility with HOL
  1839     (like the old excluded_middle_tac, but with subgoals swapped)
  1840 
  1841 
  1842 *** Internal programming interfaces ***
  1843 
  1844 * Pure: several new basic modules made available for general use, see
  1845 also src/Pure/README;
  1846 
  1847 * improved the theory data mechanism to support encapsulation (data
  1848 kind name replaced by private Object.kind, acting as authorization
  1849 key); new type-safe user interface via functor TheoryDataFun; generic
  1850 print_data function becomes basically useless;
  1851 
  1852 * removed global_names compatibility flag -- all theory declarations
  1853 are qualified by default;
  1854 
  1855 * module Pure/Syntax now offers quote / antiquote translation
  1856 functions (useful for Hoare logic etc. with implicit dependencies);
  1857 see HOL/ex/Antiquote for an example use;
  1858 
  1859 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1860 cterm -> thm;
  1861 
  1862 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1863 subgoal;
  1864 
  1865 * Display.print_goals function moved to Locale.print_goals;
  1866 
  1867 * standard print function for goals supports current_goals_markers
  1868 variable for marking begin of proof, end of proof, start of goal; the
  1869 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1870 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1871 for example;
  1872 
  1873 
  1874 
  1875 New in Isabelle98 (January 1998)
  1876 --------------------------------
  1877 
  1878 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1879 
  1880 * changed lexical syntax of terms / types: dots made part of long
  1881 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1882 
  1883 * simpset (and claset) reference variable replaced by functions
  1884 simpset / simpset_ref;
  1885 
  1886 * no longer supports theory aliases (via merge) and non-trivial
  1887 implicit merge of thms' signatures;
  1888 
  1889 * most internal names of constants changed due to qualified names;
  1890 
  1891 * changed Pure/Sequence interface (see Pure/seq.ML);
  1892 
  1893 
  1894 *** General Changes ***
  1895 
  1896 * hierachically structured name spaces (for consts, types, axms, thms
  1897 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1898 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1899 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1900 long_names for fully qualified output names; NOTE: ML programs
  1901 (special tactics, packages etc.) referring to internal names may have
  1902 to be adapted to cope with fully qualified names; in case of severe
  1903 backward campatibility problems try setting 'global_names' at compile
  1904 time to have enrything declared within a flat name space; one may also
  1905 fine tune name declarations in theories via the 'global' and 'local'
  1906 section;
  1907 
  1908 * reimplemented the implicit simpset and claset using the new anytype
  1909 data filed in signatures; references simpset:simpset ref etc. are
  1910 replaced by functions simpset:unit->simpset and
  1911 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1912 to patch your ML files accordingly;
  1913 
  1914 * HTML output now includes theory graph data for display with Java
  1915 applet or isatool browser; data generated automatically via isatool
  1916 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1917 
  1918 * defs may now be conditional; improved rewrite_goals_tac to handle
  1919 conditional equations;
  1920 
  1921 * defs now admits additional type arguments, using TYPE('a) syntax;
  1922 
  1923 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1924 creates a new theory node; implicit merge of thms' signatures is
  1925 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1926 transfer:theory->thm->thm in (rare) cases;
  1927 
  1928 * improved handling of draft signatures / theories; draft thms (and
  1929 ctyps, cterms) are automatically promoted to real ones;
  1930 
  1931 * slightly changed interfaces for oracles: admit many per theory, named
  1932 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1933 
  1934 * print_goals: optional output of const types (set show_consts and
  1935 show_types);
  1936 
  1937 * improved output of warnings (###) and errors (***);
  1938 
  1939 * subgoal_tac displays a warning if the new subgoal has type variables;
  1940 
  1941 * removed old README and Makefiles;
  1942 
  1943 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1944 
  1945 * removed obsolete init_pps and init_database;
  1946 
  1947 * deleted the obsolete tactical STATE, which was declared by
  1948     fun STATE tacfun st = tacfun st st;
  1949 
  1950 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1951 (which abbreviates $HOME);
  1952 
  1953 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1954 use isatool fixseq to adapt your ML programs (this works for fully
  1955 qualified references to the Sequence structure only!);
  1956 
  1957 * use_thy no longer requires writable current directory; it always
  1958 reloads .ML *and* .thy file, if either one is out of date;
  1959 
  1960 
  1961 *** Classical Reasoner ***
  1962 
  1963 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1964 tactics that use classical reasoning to simplify a subgoal without
  1965 splitting it into several subgoals;
  1966 
  1967 * Safe_tac: like safe_tac but uses the default claset;
  1968 
  1969 
  1970 *** Simplifier ***
  1971 
  1972 * added simplification meta rules:
  1973     (asm_)(full_)simplify: simpset -> thm -> thm;
  1974 
  1975 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1976 logics (again);
  1977 
  1978 * added prems argument to simplification procedures;
  1979 
  1980 * HOL, FOL, ZF: added infix function `addsplits':
  1981   instead of `<simpset> setloop (split_tac <thms>)'
  1982   you can simply write `<simpset> addsplits <thms>'
  1983 
  1984 
  1985 *** Syntax ***
  1986 
  1987 * TYPE('a) syntax for type reflection terms;
  1988 
  1989 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1990 
  1991 * pretty printer: changed order of mixfix annotation preference (again!);
  1992 
  1993 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1994 
  1995 
  1996 *** HOL ***
  1997 
  1998 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1999   with `addloop' of the simplifier to faciliate case splitting in premises.
  2000 
  2001 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2002 
  2003 * HOL/Auth: new protocol proofs including some for the Internet
  2004   protocol TLS;
  2005 
  2006 * HOL/Map: new theory of `maps' a la VDM;
  2007 
  2008 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2009 cancelling out common nat summands from =, <, <= (in)equalities, or
  2010 differences; simplification procedures nat_cancel_factor for
  2011 cancelling common factor from =, <, <= (in)equalities over natural
  2012 sums; nat_cancel contains both kinds of procedures, it is installed by
  2013 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2014 
  2015 * HOL/simplifier: terms of the form
  2016   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2017   are rewritten to
  2018   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2019   and those of the form
  2020   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2021   are rewritten to
  2022   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2023 
  2024 * HOL/datatype
  2025   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2026 
  2027   P(t_case f1 ... fn x) =
  2028      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2029         ...
  2030        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2031      )
  2032 
  2033   and a theorem `split_t_case_asm' of the form
  2034 
  2035   P(t_case f1 ... fn x) =
  2036     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2037         ...
  2038        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2039      )
  2040   which can be added to a simpset via `addsplits'. The existing theorems
  2041   expand_list_case and expand_option_case have been renamed to
  2042   split_list_case and split_option_case.
  2043 
  2044 * HOL/Arithmetic:
  2045   - `pred n' is automatically converted to `n-1'.
  2046     Users are strongly encouraged not to use `pred' any longer,
  2047     because it will disappear altogether at some point.
  2048   - Users are strongly encouraged to write "0 < n" rather than
  2049     "n ~= 0". Theorems and proof tools have been modified towards this
  2050     `standard'.
  2051 
  2052 * HOL/Lists:
  2053   the function "set_of_list" has been renamed "set" (and its theorems too);
  2054   the function "nth" now takes its arguments in the reverse order and
  2055   has acquired the infix notation "!" as in "xs!n".
  2056 
  2057 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2058 
  2059 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2060   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2061 
  2062 * HOL/record: extensible records with schematic structural subtyping
  2063 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2064 still lacks various theorems and concrete record syntax;
  2065 
  2066 
  2067 *** HOLCF ***
  2068 
  2069 * removed "axioms" and "generated by" sections;
  2070 
  2071 * replaced "ops" section by extended "consts" section, which is capable of
  2072   handling the continuous function space "->" directly;
  2073 
  2074 * domain package:
  2075   . proves theorems immediately and stores them in the theory,
  2076   . creates hierachical name space,
  2077   . now uses normal mixfix annotations (instead of cinfix...),
  2078   . minor changes to some names and values (for consistency),
  2079   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2080   . separator between mutual domain defs: changed "," to "and",
  2081   . improved handling of sort constraints;  now they have to
  2082     appear on the left-hand side of the equations only;
  2083 
  2084 * fixed LAM <x,y,zs>.b syntax;
  2085 
  2086 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2087 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2088 
  2089 
  2090 *** FOL and ZF ***
  2091 
  2092 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2093   with `addloop' of the simplifier to faciliate case splitting in premises.
  2094 
  2095 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2096 in HOL, they strip ALL and --> from proved theorems;
  2097 
  2098 
  2099 
  2100 New in Isabelle94-8 (May 1997)
  2101 ------------------------------
  2102 
  2103 *** General Changes ***
  2104 
  2105 * new utilities to build / run / maintain Isabelle etc. (in parts
  2106 still somewhat experimental); old Makefiles etc. still functional;
  2107 
  2108 * new 'Isabelle System Manual';
  2109 
  2110 * INSTALL text, together with ./configure and ./build scripts;
  2111 
  2112 * reimplemented type inference for greater efficiency, better error
  2113 messages and clean internal interface;
  2114 
  2115 * prlim command for dealing with lots of subgoals (an easier way of
  2116 setting goals_limit);
  2117 
  2118 
  2119 *** Syntax ***
  2120 
  2121 * supports alternative (named) syntax tables (parser and pretty
  2122 printer); internal interface is provided by add_modesyntax(_i);
  2123 
  2124 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2125 be used in conjunction with the Isabelle symbol font; uses the
  2126 "symbols" syntax table;
  2127 
  2128 * added token_translation interface (may translate name tokens in
  2129 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2130 the current print_mode); IMPORTANT: user print translation functions
  2131 are responsible for marking newly introduced bounds
  2132 (Syntax.mark_boundT);
  2133 
  2134 * token translations for modes "xterm" and "xterm_color" that display
  2135 names in bold, underline etc. or colors (which requires a color
  2136 version of xterm);
  2137 
  2138 * infixes may now be declared with names independent of their syntax;
  2139 
  2140 * added typed_print_translation (like print_translation, but may
  2141 access type of constant);
  2142 
  2143 
  2144 *** Classical Reasoner ***
  2145 
  2146 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2147 some limitations.  Blast_tac...
  2148   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2149   + ignores elimination rules that don't have the correct format
  2150         (the conclusion MUST be a formula variable)
  2151   + ignores types, which can make HOL proofs fail
  2152   + rules must not require higher-order unification, e.g. apply_type in ZF
  2153     [message "Function Var's argument not a bound variable" relates to this]
  2154   + its proof strategy is more general but can actually be slower
  2155 
  2156 * substitution with equality assumptions no longer permutes other
  2157 assumptions;
  2158 
  2159 * minor changes in semantics of addafter (now called addaltern); renamed
  2160 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2161 (and access functions for it);
  2162 
  2163 * improved combination of classical reasoner and simplifier:
  2164   + functions for handling clasimpsets
  2165   + improvement of addss: now the simplifier is called _after_ the
  2166     safe steps.
  2167   + safe variant of addss called addSss: uses safe simplifications
  2168     _during_ the safe steps. It is more complete as it allows multiple
  2169     instantiations of unknowns (e.g. with slow_tac).
  2170 
  2171 *** Simplifier ***
  2172 
  2173 * added interface for simplification procedures (functions that
  2174 produce *proven* rewrite rules on the fly, depending on current
  2175 redex);
  2176 
  2177 * ordering on terms as parameter (used for ordered rewriting);
  2178 
  2179 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2180 
  2181 * the solver is now split into a safe and an unsafe part.
  2182 This should be invisible for the normal user, except that the
  2183 functions setsolver and addsolver have been renamed to setSolver and
  2184 addSolver; added safe_asm_full_simp_tac;
  2185 
  2186 
  2187 *** HOL ***
  2188 
  2189 * a generic induction tactic `induct_tac' which works for all datatypes and
  2190 also for type `nat';
  2191 
  2192 * a generic case distinction tactic `exhaust_tac' which works for all
  2193 datatypes and also for type `nat';
  2194 
  2195 * each datatype comes with a function `size';
  2196 
  2197 * patterns in case expressions allow tuple patterns as arguments to
  2198 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2199 
  2200 * primrec now also works with type nat;
  2201 
  2202 * recdef: a new declaration form, allows general recursive functions to be
  2203 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2204 
  2205 * the constant for negation has been renamed from "not" to "Not" to
  2206 harmonize with FOL, ZF, LK, etc.;
  2207 
  2208 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2209 infinite lists;
  2210 
  2211 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2212 
  2213 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2214 problems in commutative rings, using axiomatic type classes for + and *;
  2215 
  2216 * more examples in HOL/MiniML and HOL/Auth;
  2217 
  2218 * more default rewrite rules for quantifiers, union/intersection;
  2219 
  2220 * a new constant `arbitrary == @x.False';
  2221 
  2222 * HOLCF/IOA replaces old HOL/IOA;
  2223 
  2224 * HOLCF changes: derived all rules and arities
  2225   + axiomatic type classes instead of classes
  2226   + typedef instead of faking type definitions
  2227   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2228   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2229   + eliminated the types void, one, tr
  2230   + use unit lift and bool lift (with translations) instead of one and tr
  2231   + eliminated blift from Lift3.thy (use Def instead of blift)
  2232   all eliminated rules are derived as theorems --> no visible changes ;
  2233 
  2234 
  2235 *** ZF ***
  2236 
  2237 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2238 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2239 as ZF_cs addSIs [equalityI];
  2240 
  2241 
  2242 
  2243 New in Isabelle94-7 (November 96)
  2244 ---------------------------------
  2245 
  2246 * allowing negative levels (as offsets) in prlev and choplev;
  2247 
  2248 * super-linear speedup for large simplifications;
  2249 
  2250 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2251 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2252 FAIL); can suppress it using the command Delsimps (ex_simps @
  2253 all_simps); De Morgan laws are also now included, by default;
  2254 
  2255 * improved printing of ==>  :  ~:
  2256 
  2257 * new object-logic "Sequents" adds linear logic, while replacing LK
  2258 and Modal (thanks to Sara Kalvala);
  2259 
  2260 * HOL/Auth: correctness proofs for authentication protocols;
  2261 
  2262 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2263 examples on HOL/Auth);
  2264 
  2265 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2266 the rewriter and classical reasoner simultaneously;
  2267 
  2268 * function uresult no longer returns theorems in "standard" format;
  2269 regain previous version by: val uresult = standard o uresult;
  2270 
  2271 
  2272 
  2273 New in Isabelle94-6
  2274 -------------------
  2275 
  2276 * oracles -- these establish an interface between Isabelle and trusted
  2277 external reasoners, which may deliver results as theorems;
  2278 
  2279 * proof objects (in particular record all uses of oracles);
  2280 
  2281 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2282 
  2283 * "constdefs" section in theory files;
  2284 
  2285 * "primrec" section (HOL) no longer requires names;
  2286 
  2287 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2288 
  2289 
  2290 
  2291 New in Isabelle94-5
  2292 -------------------
  2293 
  2294 * reduced space requirements;
  2295 
  2296 * automatic HTML generation from theories;
  2297 
  2298 * theory files no longer require "..." (quotes) around most types;
  2299 
  2300 * new examples, including two proofs of the Church-Rosser theorem;
  2301 
  2302 * non-curried (1994) version of HOL is no longer distributed;
  2303 
  2304 
  2305 
  2306 New in Isabelle94-4
  2307 -------------------
  2308 
  2309 * greatly reduced space requirements;
  2310 
  2311 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2312 
  2313 * searchable theorem database (see the section "Retrieving theorems" on
  2314 page 8 of the Reference Manual);
  2315 
  2316 * new examples, including Grabczewski's monumental case study of the
  2317 Axiom of Choice;
  2318 
  2319 * The previous version of HOL renamed to Old_HOL;
  2320 
  2321 * The new version of HOL (previously called CHOL) uses a curried syntax
  2322 for functions.  Application looks like f a b instead of f(a,b);
  2323 
  2324 * Mutually recursive inductive definitions finally work in HOL;
  2325 
  2326 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2327 translates to the operator "split";
  2328 
  2329 
  2330 
  2331 New in Isabelle94-3
  2332 -------------------
  2333 
  2334 * new infix operator, addss, allowing the classical reasoner to
  2335 perform simplification at each step of its search.  Example:
  2336         fast_tac (cs addss ss)
  2337 
  2338 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2339 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2340 look like (a,b) instead of <a,b>;
  2341 
  2342 * PLEASE NOTE: CHOL will eventually replace HOL!
  2343 
  2344 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2345 It translates to the operator "split".  A new theory of integers is available;
  2346 
  2347 * In ZF, integer numerals now denote two's-complement binary integers.
  2348 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2349 
  2350 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2351 of the Axiom of Choice;
  2352 
  2353 
  2354 
  2355 New in Isabelle94-2
  2356 -------------------
  2357 
  2358 * Significantly faster resolution;
  2359 
  2360 * the different sections in a .thy file can now be mixed and repeated
  2361 freely;
  2362 
  2363 * Database of theorems for FOL, HOL and ZF.  New
  2364 commands including qed, qed_goal and bind_thm store theorems in the database.
  2365 
  2366 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2367 a given theory (thms_of), or find out what theory a theorem was proved in
  2368 (theory_of_thm);
  2369 
  2370 * Bugs fixed in the inductive definition and datatype packages;
  2371 
  2372 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2373 and HOL_dup_cs obsolete;
  2374 
  2375 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2376 have been removed;
  2377 
  2378 * Simpler definition of function space in ZF;
  2379 
  2380 * new results about cardinal and ordinal arithmetic in ZF;
  2381 
  2382 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2383 types;
  2384 
  2385 
  2386 $Id$