NEWS
author schirmer
Mon May 12 14:16:38 2003 +0200 (2003-05-12)
changeset 14010 32faa7e2e767
parent 14008 f843528b9f3c
child 14011 5fa103f5618c
permissions -rw-r--r--
Bali
     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   - No longer aborts on failed congruence proof.  Instead, the
    50     congruence is ignored.
    51 
    52 * Pure: New generic framework for extracting programs from constructive
    53   proofs. See HOL/Extraction.thy for an example instantiation, as well
    54   as HOL/Extraction for some case studies.
    55 
    56 * Pure: The main goal of the proof state is no longer shown by default, only
    57 the subgoals. This behaviour is controlled by a new flag.
    58    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
    59 (ML: Proof.show_main_goal).
    60 
    61 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
    62 rules whose conclusion matches subgoal 1:
    63       PG menu: Isabelle/Isar -> Show me -> matching rules
    64 The rules are ordered by how closely they match the subgoal.
    65 In particular, rules that solve a subgoal outright are displayed first
    66 (or rather last, the way they are printed).
    67 (ML: ProofGeneral.print_intros())
    68 
    69 * Pure: New flag trace_unify_fail causes unification to print
    70 diagnostic information (PG: in trace buffer) when it fails. This is
    71 useful for figuring out why single step proofs like rule, erule or
    72 assumption failed.
    73 
    74 * Pure: Locale specifications now produce predicate definitions
    75 according to the body of text (covering assumptions modulo local
    76 definitions); predicate "loc_axioms" covers newly introduced text,
    77 while "loc" is cumulative wrt. all included locale expressions; the
    78 latter view is presented only on export into the global theory
    79 context; potential INCOMPATIBILITY, use "(open)" option to fall back
    80 on the old view without predicates;
    81 
    82 * Pure: predefined locales "var" and "struct" are useful for sharing
    83 parameters (as in CASL, for example); just specify something like
    84 ``var x + var y + struct M'' as import;
    85 
    86 * Pure: improved thms_containing: proper indexing of facts instead of
    87 raw theorems; check validity of results wrt. current name space;
    88 include local facts of proof configuration (also covers active
    89 locales), cover fixed variables in index; may use "_" in term
    90 specification; an optional limit for the number of printed facts may
    91 be given (the default is 40);
    92 
    93 * Pure: disallow duplicate fact bindings within new-style theory files
    94 (batch-mode only);
    95 
    96 * Provers: improved induct method: assumptions introduced by case
    97 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
    98 the goal statement); "foo" still refers to all facts collectively;
    99 
   100 * Provers: the function blast.overloaded has been removed: all constants
   101 are regarded as potentially overloaded, which improves robustness in exchange
   102 for slight decrease in efficiency;
   103 
   104 * Provers/linorder: New generic prover for transitivity reasoning over
   105 linear orders.  Note: this prover is not efficient!
   106 
   107 * Isar: preview of problems to finish 'show' now produce an error
   108 rather than just a warning (in interactive mode);
   109 
   110 
   111 *** HOL ***
   112 
   113 * arith(_tac)
   114 
   115  - Produces a counter example if it cannot prove a goal.
   116    Note that the counter example may be spurious if the goal is not a formula
   117    of quantifier-free linear arithmetic.
   118    In ProofGeneral the counter example appears in the trace buffer.
   119 
   120  - Knows about div k and mod k where k is a numeral of type nat or int.
   121 
   122  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   123    linear arithmetic fails. This takes account of quantifiers and divisibility.
   124    Presburger arithmetic can also be called explicitly via presburger(_tac). 
   125 
   126 * simp's arithmetic capabilities have been enhanced a bit: it now
   127 takes ~= in premises into account (by performing a case split);
   128 
   129 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   130 are distributed over a sum of terms;
   131 
   132 * New tactic "trans_tac" and method "trans" instantiate
   133 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   134 "<=", "<" and "="). 
   135 
   136 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main 
   137 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   138 
   139 * 'typedef' command has new option "open" to suppress the set
   140 definition;
   141 
   142 * functions Min and Max on finite sets have been introduced (theory
   143 Finite_Set);
   144 
   145 * attribute [symmetric] now works for relations as well; it turns
   146 (x,y) : R^-1 into (y,x) : R, and vice versa;
   147 
   148 * induct over a !!-quantified statement (say !!x1..xn):
   149   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   150 
   151 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   152 %x. None. Warning: empty_def now refers to the previously hidden definition
   153 of the empty set.
   154 
   155 * Algebra: contains a new formalization of group theory, using locales
   156 with implicit structures.  Also a new formalization of ring theory and
   157 and univariate polynomials;
   158 
   159 * GroupTheory: deleted, since its material has been moved to Algebra;
   160 
   161 * Complex: new directory of the complex numbers with numeric constants, 
   162 nonstandard complex numbers, and some complex analysis, standard and 
   163 nonstandard (Jacques Fleuriot);
   164 
   165 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   166 
   167 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques 
   168 Fleuriot);
   169 
   170 * Real/HahnBanach: updated and adapted to locales;
   171 
   172 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   173 Gray and Kramer);
   174 
   175 * UNITY: added the Meier-Sanders theory of progress sets;
   176 
   177 * Bali: Java source language formalization. Type system, operational
   178 semantics, axiomatic semantics. Supported language features:
   179 classes, interfaces, objects,virtual methods, static methods,
   180 static/instance fields, arrays, access modifiers, definite
   181 assignment, exceptions.
   182 
   183 *** ZF ***
   184 
   185 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   186 universe, etc.);
   187 
   188 * Main ZF: virtually all theories converted to new-style format;
   189 
   190 
   191 *** ML ***
   192 
   193 * Pure: Tactic.prove provides sane interface for internal proofs;
   194 omits the infamous "standard" operation, so this is more appropriate
   195 than prove_goalw_cterm in many situations (e.g. in simprocs);
   196 
   197 * Pure: improved error reporting of simprocs;
   198 
   199 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   200 up simprocs;
   201 
   202 
   203 *** Document preparation ***
   204 
   205 * uses \par instead of \\ for line breaks in theory text. This may
   206 shift some page breaks in large documents. To get the old behaviour
   207 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   208 
   209 * minimized dependencies of isabelle.sty and isabellesym.sty on 
   210 other packages
   211 
   212 * \<euro> now needs package babel/greek instead of marvosym (which
   213 broke \Rightarrow)
   214 
   215 * normal size for \<zero>...\<nine> (uses \mathbf instead of 
   216 textcomp package)
   217 
   218 
   219 New in Isabelle2002 (March 2002)
   220 --------------------------------
   221 
   222 *** Document preparation ***
   223 
   224 * greatly simplified document preparation setup, including more
   225 graceful interpretation of isatool usedir -i/-d/-D options, and more
   226 instructive isatool mkdir; users should basically be able to get
   227 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   228 users may run a separate document processing stage manually like this:
   229 "isatool usedir -D output HOL Test && isatool document Test/output";
   230 
   231 * theory dependency graph may now be incorporated into documents;
   232 isatool usedir -g true will produce session_graph.eps/.pdf for use
   233 with \includegraphics of LaTeX;
   234 
   235 * proper spacing of consecutive markup elements, especially text
   236 blocks after section headings;
   237 
   238 * support bold style (for single symbols only), input syntax is like
   239 this: "\<^bold>\<alpha>" or "\<^bold>A";
   240 
   241 * \<bullet> is now output as bold \cdot by default, which looks much
   242 better in printed text;
   243 
   244 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   245 note that these symbols are currently unavailable in Proof General /
   246 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   247 
   248 * isatool latex no longer depends on changed TEXINPUTS, instead
   249 isatool document copies the Isabelle style files to the target
   250 location;
   251 
   252 
   253 *** Isar ***
   254 
   255 * Pure/Provers: improved proof by cases and induction;
   256   - 'case' command admits impromptu naming of parameters (such as
   257     "case (Suc n)");
   258   - 'induct' method divinates rule instantiation from the inductive
   259     claim; no longer requires excessive ?P bindings for proper
   260     instantiation of cases;
   261   - 'induct' method properly enumerates all possibilities of set/type
   262     rules; as a consequence facts may be also passed through *type*
   263     rules without further ado;
   264   - 'induct' method now derives symbolic cases from the *rulified*
   265     rule (before it used to rulify cases stemming from the internal
   266     atomized version); this means that the context of a non-atomic
   267     statement becomes is included in the hypothesis, avoiding the
   268     slightly cumbersome show "PROP ?case" form;
   269   - 'induct' may now use elim-style induction rules without chaining
   270     facts, using ``missing'' premises from the goal state; this allows
   271     rules stemming from inductive sets to be applied in unstructured
   272     scripts, while still benefitting from proper handling of non-atomic
   273     statements; NB: major inductive premises need to be put first, all
   274     the rest of the goal is passed through the induction;
   275   - 'induct' proper support for mutual induction involving non-atomic
   276     rule statements (uses the new concept of simultaneous goals, see
   277     below);
   278   - append all possible rule selections, but only use the first
   279     success (no backtracking);
   280   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   281   - undeclared rule case names default to numbers 1, 2, 3, ...;
   282   - added 'print_induct_rules' (covered by help item in recent Proof
   283     General versions);
   284   - moved induct/cases attributes to Pure, methods to Provers;
   285   - generic method setup instantiated for FOL and HOL;
   286 
   287 * Pure: support multiple simultaneous goal statements, for example
   288 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   289 meta-level mechanism, this acts as if several individual goals had
   290 been stated separately; in particular common proof methods need to be
   291 repeated in order to cover all claims; note that a single elimination
   292 step is *not* sufficient to establish the two conjunctions, so this
   293 fails:
   294 
   295   assume "A & B" then have A and B ..   (*".." fails*)
   296 
   297 better use "obtain" in situations as above; alternative refer to
   298 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   299 
   300 * Pure: proper integration with ``locales''; unlike the original
   301 version by Florian Kammüller, Isar locales package high-level proof
   302 contexts rather than raw logical ones (e.g. we admit to include
   303 attributes everywhere); operations on locales include merge and
   304 rename; support for implicit arguments (``structures''); simultaneous
   305 type-inference over imports and text; see also HOL/ex/Locales.thy for
   306 some examples;
   307 
   308 * Pure: the following commands have been ``localized'', supporting a
   309 target locale specification "(in name)": 'lemma', 'theorem',
   310 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   311 stored both within the locale and at the theory level (exported and
   312 qualified by the locale name);
   313 
   314 * Pure: theory goals may now be specified in ``long'' form, with
   315 ad-hoc contexts consisting of arbitrary locale elements. for example
   316 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   317 definitions may be given, too); the result is a meta-level rule with
   318 the context elements being discharged in the obvious way;
   319 
   320 * Pure: new proof command 'using' allows to augment currently used
   321 facts after a goal statement ('using' is syntactically analogous to
   322 'apply', but acts on the goal's facts only); this allows chained facts
   323 to be separated into parts given before and after a claim, as in
   324 ``from a and b have C using d and e <proof>'';
   325 
   326 * Pure: renamed "antecedent" case to "rule_context";
   327 
   328 * Pure: new 'judgment' command records explicit information about the
   329 object-logic embedding (used by several tools internally); no longer
   330 use hard-wired "Trueprop";
   331 
   332 * Pure: added 'corollary' command;
   333 
   334 * Pure: fixed 'token_translation' command;
   335 
   336 * Pure: removed obsolete 'exported' attribute;
   337 
   338 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   339 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   340 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   341 
   342 * Pure: method 'atomize' presents local goal premises as object-level
   343 statements (atomic meta-level propositions); setup controlled via
   344 rewrite rules declarations of 'atomize' attribute; example
   345 application: 'induct' method with proper rule statements in improper
   346 proof *scripts*;
   347 
   348 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   349 now consider the syntactic context of assumptions, giving a better
   350 chance to get type-inference of the arguments right (this is
   351 especially important for locales);
   352 
   353 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   354 mode;
   355 
   356 * Pure/obtain: the formal conclusion "thesis", being marked as
   357 ``internal'', may no longer be reference directly in the text;
   358 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   359 situations;
   360 
   361 * Pure: generic 'sym' attribute which declares a rule both as pure
   362 'elim?' and for the 'symmetric' operation;
   363 
   364 * Pure: marginal comments ``--'' may now occur just anywhere in the
   365 text; the fixed correlation with particular command syntax has been
   366 discontinued;
   367 
   368 * Pure: new method 'rules' is particularly well-suited for proof
   369 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   370 but often produces more compact proof terms with less detours;
   371 
   372 * Pure/Provers/classical: simplified integration with pure rule
   373 attributes and methods; the classical "intro?/elim?/dest?"
   374 declarations coincide with the pure ones; the "rule" method no longer
   375 includes classically swapped intros; "intro" and "elim" methods no
   376 longer pick rules from the context; also got rid of ML declarations
   377 AddXIs/AddXEs/AddXDs; all of this has some potential for
   378 INCOMPATIBILITY;
   379 
   380 * Provers/classical: attribute 'swapped' produces classical inversions
   381 of introduction rules;
   382 
   383 * Provers/simplifier: 'simplified' attribute may refer to explicit
   384 rules instead of full simplifier context; 'iff' attribute handles
   385 conditional rules;
   386 
   387 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   388 
   389 * HOL: 'recdef' now fails on unfinished automated proofs, use
   390 "(permissive)" option to recover old behavior;
   391 
   392 * HOL: 'inductive' no longer features separate (collective) attributes
   393 for 'intros' (was found too confusing);
   394 
   395 * HOL: properly declared induction rules less_induct and
   396 wf_induct_rule;
   397 
   398 
   399 *** HOL ***
   400 
   401 * HOL: moved over to sane numeral syntax; the new policy is as
   402 follows:
   403 
   404   - 0 and 1 are polymorphic constants, which are defined on any
   405   numeric type (nat, int, real etc.);
   406 
   407   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   408   binary representation internally;
   409 
   410   - type nat has special constructor Suc, and generally prefers Suc 0
   411   over 1::nat and Suc (Suc 0) over 2::nat;
   412 
   413 This change may cause significant problems of INCOMPATIBILITY; here
   414 are some hints on converting existing sources:
   415 
   416   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   417   entities, so expressions involving "-" (unary or binary minus) need
   418   to be spaced properly;
   419 
   420   - existing occurrences of "1" may need to be constraint "1::nat" or
   421   even replaced by Suc 0; similar for old "2";
   422 
   423   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   424 
   425   - remove all special provisions on numerals in proofs;
   426 
   427 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   428 representation (depends on bin_arith_simps in the default context);
   429 
   430 * HOL: symbolic syntax for x^2 (numeral 2);
   431 
   432 * HOL: the class of all HOL types is now called "type" rather than
   433 "term"; INCOMPATIBILITY, need to adapt references to this type class
   434 in axclass/classes, instance/arities, and (usually rare) occurrences
   435 in typings (of consts etc.); internally the class is called
   436 "HOL.type", ML programs should refer to HOLogic.typeS;
   437 
   438 * HOL/record package improvements:
   439   - new derived operations "fields" to build a partial record section,
   440     "extend" to promote a fixed record to a record scheme, and
   441     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   442     declared as simp by default;
   443   - shared operations ("more", "fields", etc.) now need to be always
   444     qualified) --- potential INCOMPATIBILITY;
   445   - removed "make_scheme" operations (use "make" with "extend") --
   446     INCOMPATIBILITY;
   447   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   448   - provides cases/induct rules for use with corresponding Isar
   449     methods (for concrete records, record schemes, concrete more
   450     parts, and schematic more parts -- in that order);
   451   - internal definitions directly based on a light-weight abstract
   452     theory of product types over typedef rather than datatype;
   453 
   454 * HOL: generic code generator for generating executable ML code from
   455 specifications; specific support for HOL constructs such as inductive
   456 datatypes and sets, as well as recursive functions; can be invoked
   457 via 'generate_code' theory section;
   458 
   459 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   460 
   461 * HOL: consolidated and renamed several theories.  In particular:
   462 	Ord.thy has been absorbed into HOL.thy
   463 	String.thy has been absorbed into List.thy
   464  
   465 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   466 (beware of argument permutation!);
   467 
   468 * HOL: linorder_less_split superseded by linorder_cases;
   469 
   470 * HOL/List: "nodups" renamed to "distinct";
   471 
   472 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   473 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   474   - Ex_def has changed, now need to use some_eq_ex
   475 
   476 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   477 in this (rare) case use:
   478 
   479   delSWrapper "split_all_tac"
   480   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   481 
   482 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   483 MAY FAIL;
   484 
   485 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   486 Isabelle's type classes, ^ on functions and relations has too general
   487 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   488 necessary to attach explicit type constraints;
   489 
   490 * HOL/Relation: the prefix name of the infix "O" has been changed from
   491 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   492 renamed accordingly (eg "compI" -> "rel_compI").
   493 
   494 * HOL: syntax translations now work properly with numerals and records
   495 expressions;
   496 
   497 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   498 of "lam" -- INCOMPATIBILITY;
   499 
   500 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   501 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   502 renamed "Product_Type.unit";
   503 
   504 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   505 
   506 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   507 the "cases" method);
   508 
   509 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   510 Florian Kammüller);
   511 
   512 * HOL/IMP: updated and converted to new-style theory format; several
   513 parts turned into readable document, with proper Isar proof texts and
   514 some explanations (by Gerwin Klein);
   515 
   516 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   517 
   518 * HOL-Hyperreal is now a logic image;
   519 
   520 
   521 *** HOLCF ***
   522 
   523 * Isar: consts/constdefs supports mixfix syntax for continuous
   524 operations;
   525 
   526 * Isar: domain package adapted to new-style theory format, e.g. see
   527 HOLCF/ex/Dnat.thy;
   528 
   529 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   530 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   531 lift.induct_tac, always use UU instead of Undef;
   532 
   533 * HOLCF/IMP: updated and converted to new-style theory;
   534 
   535 
   536 *** ZF ***
   537 
   538 * Isar: proper integration of logic-specific tools and packages,
   539 including theory commands '(co)inductive', '(co)datatype',
   540 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   541 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   542 
   543 * theory Main no longer includes AC; for the Axiom of Choice, base
   544 your theory on Main_ZFC;
   545 
   546 * the integer library now covers quotients and remainders, with many
   547 laws relating division to addition, multiplication, etc.;
   548 
   549 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   550 typeless version of the formalism;
   551 
   552 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   553 format;
   554 
   555 * ZF/Induct: new directory for examples of inductive definitions,
   556 including theory Multiset for multiset orderings; converted to
   557 new-style theory format;
   558 
   559 * ZF: many new theorems about lists, ordinals, etc.;
   560 
   561 
   562 *** General ***
   563 
   564 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   565 variable proof controls level of detail: 0 = no proofs (only oracle
   566 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   567 also ref manual for further ML interfaces;
   568 
   569 * Pure/axclass: removed obsolete ML interface
   570 goal_subclass/goal_arity;
   571 
   572 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   573 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   574 separate tokens, so expressions involving minus need to be spaced
   575 properly;
   576 
   577 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   578 rather than "infixl" or "infixr";
   579 
   580 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   581 sort constraint specifications in type inference; e.g. "x::_::foo"
   582 ensures that the type of "x" is of sort "foo" (but not necessarily a
   583 type variable);
   584 
   585 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   586 control output of nested => (types); the default behavior is
   587 "type_brackets";
   588 
   589 * Pure/syntax: builtin parse translation for "_constify" turns valued
   590 tokens into AST constants;
   591 
   592 * Pure/syntax: prefer later declarations of translations and print
   593 translation functions; potential INCOMPATIBILITY: need to reverse
   594 multiple declarations for same syntax element constant;
   595 
   596 * Pure/show_hyps reset by default (in accordance to existing Isar
   597 practice);
   598 
   599 * Provers/classical: renamed addaltern to addafter, addSaltern to
   600 addSafter;
   601 
   602 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   603 as well;
   604 
   605 * system: tested support for MacOS X; should be able to get Isabelle +
   606 Proof General to work in a plain Terminal after installing Poly/ML
   607 (e.g. from the Isabelle distribution area) and GNU bash alone
   608 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   609 support requires further installations, e.g. from
   610 http://fink.sourceforge.net/);
   611 
   612 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   613 
   614 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   615 of 40 MB), cf. ML_OPTIONS;
   616 
   617 * system: Proof General keywords specification is now part of the
   618 Isabelle distribution (see etc/isar-keywords.el);
   619 
   620 * system: support for persistent Proof General sessions (refrain from
   621 outdating all loaded theories on startup); user may create writable
   622 logic images like this: ``isabelle -q HOL Test'';
   623 
   624 * system: smart selection of Isabelle process versus Isabelle
   625 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   626 run both "isabelle" and "Isabelle" even if file names are badly
   627 damaged (executable inspects the case of the first letter of its own
   628 name); added separate "isabelle-process" and "isabelle-interface";
   629 
   630 * system: refrain from any attempt at filtering input streams; no
   631 longer support ``8bit'' encoding of old isabelle font, instead proper
   632 iso-latin characters may now be used; the related isatools
   633 "symbolinput" and "nonascii" have disappeared as well;
   634 
   635 * system: removed old "xterm" interface (the print modes "xterm" and
   636 "xterm_color" are still available for direct use in a suitable
   637 terminal);
   638 
   639 
   640 
   641 New in Isabelle99-2 (February 2001)
   642 -----------------------------------
   643 
   644 *** Overview of INCOMPATIBILITIES ***
   645 
   646 * HOL: please note that theories in the Library and elsewhere often use the
   647 new-style (Isar) format; to refer to their theorems in an ML script you must
   648 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   649 
   650 * HOL: inductive package no longer splits induction rule aggressively,
   651 but only as far as specified by the introductions given; the old
   652 format may be recovered via ML function complete_split_rule or attribute
   653 'split_rule (complete)';
   654 
   655 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   656 gfp_Tarski to gfp_unfold;
   657 
   658 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   659 
   660 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   661 relation); infix "^^" has been renamed "``"; infix "``" has been
   662 renamed "`"; "univalent" has been renamed "single_valued";
   663 
   664 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   665 operation;
   666 
   667 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   668 
   669 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   670 
   671 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   672 consequence, it is no longer monotonic wrt. the local goal context
   673 (which is now passed through the inductive cases);
   674 
   675 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   676 \<gg> to \<ggreater>;
   677 
   678 
   679 *** Document preparation ***
   680 
   681 * \isabellestyle{NAME} selects version of Isabelle output (currently
   682 available: are "it" for near math-mode best-style output, "sl" for
   683 slanted text style, and "tt" for plain type-writer; if no
   684 \isabellestyle command is given, output is according to slanted
   685 type-writer);
   686 
   687 * support sub/super scripts (for single symbols only), input syntax is
   688 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   689 
   690 * some more standard symbols; see Appendix A of the system manual for
   691 the complete list of symbols defined in isabellesym.sty;
   692 
   693 * improved isabelle style files; more abstract symbol implementation
   694 (should now use \isamath{...} and \isatext{...} in custom symbol
   695 definitions);
   696 
   697 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   698 state; Note that presentation of goal states does not conform to
   699 actual human-readable proof documents.  Please do not include goal
   700 states into document output unless you really know what you are doing!
   701 
   702 * proper indentation of antiquoted output with proportional LaTeX
   703 fonts;
   704 
   705 * no_document ML operator temporarily disables LaTeX document
   706 generation;
   707 
   708 * isatool unsymbolize tunes sources for plain ASCII communication;
   709 
   710 
   711 *** Isar ***
   712 
   713 * Pure: Isar now suffers initial goal statements to contain unbound
   714 schematic variables (this does not conform to actual readable proof
   715 documents, due to unpredictable outcome and non-compositional proof
   716 checking); users who know what they are doing may use schematic goals
   717 for Prolog-style synthesis of proven results;
   718 
   719 * Pure: assumption method (an implicit finishing) now handles actual
   720 rules as well;
   721 
   722 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   723 initial goal, declare "that" only as Pure intro (only for single
   724 steps); the "that" rule assumption may now be involved in implicit
   725 finishing, thus ".." becomes a feasible for trivial obtains;
   726 
   727 * Pure: default proof step now includes 'intro_classes'; thus trivial
   728 instance proofs may be performed by "..";
   729 
   730 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   731 statements as well;
   732 
   733 * Pure: more robust selection of calculational rules;
   734 
   735 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   736 rule (as well as the assumption rule);
   737 
   738 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   739 lemmas, using the graph browser tool;
   740 
   741 * Pure: predict failure of "show" in interactive mode;
   742 
   743 * Pure: 'thms_containing' now takes actual terms as arguments;
   744 
   745 * HOL: improved method 'induct' --- now handles non-atomic goals
   746 (potential INCOMPATIBILITY); tuned error handling;
   747 
   748 * HOL: cases and induct rules now provide explicit hints about the
   749 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   750 any remaining facts are inserted into the goal verbatim;
   751 
   752 * HOL: local contexts (aka cases) may now contain term bindings as
   753 well; the 'cases' and 'induct' methods new provide a ?case binding for
   754 the result to be shown in each case;
   755 
   756 * HOL: added 'recdef_tc' command;
   757 
   758 * isatool convert assists in eliminating legacy ML scripts;
   759 
   760 
   761 *** HOL ***
   762 
   763 * HOL/Library: a collection of generic theories to be used together
   764 with main HOL; the theory loader path already includes this directory
   765 by default; the following existing theories have been moved here:
   766 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   767 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   768 
   769 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   770 modelling and verification task performed in Isabelle/HOL +
   771 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   772 
   773 * HOL/Algebra: special summation operator SUM no longer exists, it has
   774 been replaced by setsum; infix 'assoc' now has priority 50 (like
   775 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   776 'domain', this makes the theory consistent with mathematical
   777 literature;
   778 
   779 * HOL basics: added overloaded operations "inverse" and "divide"
   780 (infix "/"), syntax for generic "abs" operation, generic summation
   781 operator \<Sum>;
   782 
   783 * HOL/typedef: simplified package, provide more useful rules (see also
   784 HOL/subset.thy);
   785 
   786 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   787 now expressed as a proper nested rule (old-style tactic scripts may
   788 require atomize_strip_tac to cope with non-atomic premises);
   789 
   790 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   791 to "split_conv" (old name still available for compatibility);
   792 
   793 * HOL: improved concrete syntax for strings (e.g. allows translation
   794 rules with string literals);
   795 
   796 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   797  and Fleuriot's mechanization of analysis, including the transcendental
   798  functions for the reals;
   799 
   800 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   801 
   802 
   803 *** CTT ***
   804 
   805 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   806 "lam" is displayed as TWO lambda-symbols
   807 
   808 * CTT: theory Main now available, containing everything (that is, Bool
   809 and Arith);
   810 
   811 
   812 *** General ***
   813 
   814 * Pure: the Simplifier has been implemented properly as a derived rule
   815 outside of the actual kernel (at last!); the overall performance
   816 penalty in practical applications is about 50%, while reliability of
   817 the Isabelle inference kernel has been greatly improved;
   818 
   819 * print modes "brackets" and "no_brackets" control output of nested =>
   820 (types) and ==> (props); the default behaviour is "brackets";
   821 
   822 * Provers: fast_tac (and friends) now handle actual object-logic rules
   823 as assumptions as well;
   824 
   825 * system: support Poly/ML 4.0;
   826 
   827 * system: isatool install handles KDE version 1 or 2;
   828 
   829 
   830 
   831 New in Isabelle99-1 (October 2000)
   832 ----------------------------------
   833 
   834 *** Overview of INCOMPATIBILITIES ***
   835 
   836 * HOL: simplification of natural numbers is much changed; to partly
   837 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   838 issue the following ML commands:
   839 
   840   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   841   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   842 
   843 * HOL: simplification no longer dives into case-expressions; this is
   844 controlled by "t.weak_case_cong" for each datatype t;
   845 
   846 * HOL: nat_less_induct renamed to less_induct;
   847 
   848 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   849 fixsome to patch .thy and .ML sources automatically;
   850 
   851   select_equality  -> some_equality
   852   select_eq_Ex     -> some_eq_ex
   853   selectI2EX       -> someI2_ex
   854   selectI2         -> someI2
   855   selectI          -> someI
   856   select1_equality -> some1_equality
   857   Eps_sym_eq       -> some_sym_eq_trivial
   858   Eps_eq           -> some_eq_trivial
   859 
   860 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   861 
   862 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   863 instead);
   864 
   865 * HOL: the recursion equations generated by 'recdef' are now called
   866 f.simps instead of f.rules;
   867 
   868 * HOL: qed_spec_mp now also handles bounded ALL as well;
   869 
   870 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   871 sometimes be needed;
   872 
   873 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   874 
   875 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   876 
   877 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   878 product is now "<*>" instead of "Times"; the lexicographic product is
   879 now "<*lex*>" instead of "**";
   880 
   881 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   882 of main HOL, but was unused); better use HOL's datatype package;
   883 
   884 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   885 the old syntax may be recovered as follows:
   886 
   887   syntax (symbols)
   888     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   889       (infixl "\\<oplus>" 100)
   890 
   891 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   892 
   893 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   894 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   895 internally;
   896 
   897 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   898 changed from A/r to A//r;
   899 
   900 * ZF: new treatment of arithmetic (nat & int) may break some old
   901 proofs;
   902 
   903 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   904 rulify -> rule_format, elimify -> elim_format, ...);
   905 
   906 * Isar/Provers: intro/elim/dest attributes changed; renamed
   907 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   908 should have to change intro!! to intro? only); replaced "delrule" by
   909 "rule del";
   910 
   911 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   912 
   913 * Provers: strengthened force_tac by using new first_best_tac;
   914 
   915 * LaTeX document preparation: several changes of isabelle.sty (see
   916 lib/texinputs);
   917 
   918 
   919 *** Document preparation ***
   920 
   921 * formal comments (text blocks etc.) in new-style theories may now
   922 contain antiquotations of thm/prop/term/typ/text to be presented
   923 according to latex print mode; concrete syntax is like this:
   924 @{term[show_types] "f(x) = a + x"};
   925 
   926 * isatool mkdir provides easy setup of Isabelle session directories,
   927 including proper document sources;
   928 
   929 * generated LaTeX sources are now deleted after successful run
   930 (isatool document -c); may retain a copy somewhere else via -D option
   931 of isatool usedir;
   932 
   933 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   934 style files, achieving self-contained LaTeX sources and simplifying
   935 LaTeX debugging;
   936 
   937 * old-style theories now produce (crude) LaTeX output as well;
   938 
   939 * browser info session directories are now self-contained (may be put
   940 on WWW server seperately); improved graphs of nested sessions; removed
   941 graph for 'all sessions';
   942 
   943 * several improvements in isabelle style files; \isabellestyle{it}
   944 produces fake math mode output; \isamarkupheader is now \section by
   945 default; see lib/texinputs/isabelle.sty etc.;
   946 
   947 
   948 *** Isar ***
   949 
   950 * Isar/Pure: local results and corresponding term bindings are now
   951 subject to Hindley-Milner polymorphism (similar to ML); this
   952 accommodates incremental type-inference very nicely;
   953 
   954 * Isar/Pure: new derived language element 'obtain' supports
   955 generalized existence reasoning;
   956 
   957 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   958 support accumulation of results, without applying any rules yet;
   959 useful to collect intermediate results without explicit name
   960 references, and for use with transitivity rules with more than 2
   961 premises;
   962 
   963 * Isar/Pure: scalable support for case-analysis type proofs: new
   964 'case' language element refers to local contexts symbolically, as
   965 produced by certain proof methods; internally, case names are attached
   966 to theorems as "tags";
   967 
   968 * Isar/Pure: theory command 'hide' removes declarations from
   969 class/type/const name spaces;
   970 
   971 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   972 indicate potential overloading;
   973 
   974 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   975 
   976 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   977 "{a,b,c}" instead of {a,b,c};
   978 
   979 * Isar/Pure now provides its own version of intro/elim/dest
   980 attributes; useful for building new logics, but beware of confusion
   981 with the version in Provers/classical;
   982 
   983 * Isar/Pure: the local context of (non-atomic) goals is provided via
   984 case name 'antecedent';
   985 
   986 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   987 to the current context is now done automatically);
   988 
   989 * Isar/Pure: theory command 'method_setup' provides a simple interface
   990 for definining proof methods in ML;
   991 
   992 * Isar/Provers: intro/elim/dest attributes changed; renamed
   993 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   994 most cases, one should have to change intro!! to intro? only);
   995 replaced "delrule" by "rule del";
   996 
   997 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   998 'symmetric' attribute (the latter supercedes [RS sym]);
   999 
  1000 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1001 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1002 well (including splits);
  1003 
  1004 * Isar/Provers: Simplifier and Classical methods now support all kind
  1005 of modifiers used in the past, including 'cong', 'iff', etc.
  1006 
  1007 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1008 of Simplifier and Classical reasoner);
  1009 
  1010 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1011 now support named cases; major packages (inductive, datatype, primrec,
  1012 recdef) support case names and properly name parameters;
  1013 
  1014 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1015 monotonicity conditions are extracted to be proven at end of
  1016 calculations;
  1017 
  1018 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1019 method anyway;
  1020 
  1021 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1022 split_if split_if_asm; datatype package provides theorems foo.splits =
  1023 foo.split foo.split_asm for each datatype;
  1024 
  1025 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1026 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1027 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1028 use "(cases (simplified))" method in proper proof texts);
  1029 
  1030 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1031 
  1032 * Isar: names of theorems etc. may be natural numbers as well;
  1033 
  1034 * Isar: 'pr' command: optional arguments for goals_limit and
  1035 ProofContext.prems_limit; no longer prints theory contexts, but only
  1036 proof states;
  1037 
  1038 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1039 additional print modes to be specified; e.g. "pr(latex)" will print
  1040 proof state according to the Isabelle LaTeX style;
  1041 
  1042 * Isar: improved support for emulating tactic scripts, including proof
  1043 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1044 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1045 (for HOL datatypes);
  1046 
  1047 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1048 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1049 'proof method scripts' have to be in depth-first order;
  1050 
  1051 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1052 
  1053 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1054 should instead use individual commands for printing items
  1055 (print_commands, print_methods etc.);
  1056 
  1057 * Isar: added 'nothing' --- the empty list of theorems;
  1058 
  1059 
  1060 *** HOL ***
  1061 
  1062 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1063 corresponding virtual machine and a specification of its bytecode
  1064 verifier and a lightweight bytecode verifier, including proofs of
  1065 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1066 Cornelia Pusch (see also the homepage of project Bali at
  1067 http://isabelle.in.tum.de/Bali/);
  1068 
  1069 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1070 Clemens Ballarin;
  1071 
  1072 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1073 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1074 Rasmussen;
  1075 
  1076 * HOL/Lattice: fundamental concepts of lattice theory and order
  1077 structures, including duals, properties of bounds versus algebraic
  1078 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1079 Theorem for complete lattices etc.; may also serve as a demonstration
  1080 for abstract algebraic reasoning using axiomatic type classes, and
  1081 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1082 
  1083 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1084 von Oheimb;
  1085 
  1086 * HOL/IMPP: extension of IMP with local variables and mutually
  1087 recursive procedures, by David von Oheimb;
  1088 
  1089 * HOL/Lambda: converted into new-style theory and document;
  1090 
  1091 * HOL/ex/Multiquote: example of multiple nested quotations and
  1092 anti-quotations -- basically a generalized version of de-Bruijn
  1093 representation; very useful in avoiding lifting of operations;
  1094 
  1095 * HOL/record: added general record equality rule to simpset; fixed
  1096 select-update simplification procedure to handle extended records as
  1097 well; admit "r" as field name;
  1098 
  1099 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1100 other numeric types and also as the identity of groups, rings, etc.;
  1101 
  1102 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1103 Types nat and int belong to this axclass;
  1104 
  1105 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1106    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1107    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1108   two terms #m*u and #n*u are replaced by #(m+n)*u
  1109     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1110   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1111     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1112 
  1113 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1114 powerful prover for predicate logic but knows nothing of clasets; see
  1115 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1116 
  1117 * HOL: new version of "case_tac" subsumes both boolean case split and
  1118 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1119 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1120 
  1121 * HOL: simplification no longer dives into case-expressions: only the
  1122 selector expression is simplified, but not the remaining arms; to
  1123 enable full simplification of case-expressions for datatype t, you may
  1124 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1125 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1126 
  1127 * HOL/recdef: the recursion equations generated by 'recdef' for
  1128 function 'f' are now called f.simps instead of f.rules; if all
  1129 termination conditions are proved automatically, these simplification
  1130 rules are added to the simpset, as in primrec; rules may be named
  1131 individually as well, resulting in a separate list of theorems for
  1132 each equation;
  1133 
  1134 * HOL/While is a new theory that provides a while-combinator. It
  1135 permits the definition of tail-recursive functions without the
  1136 provision of a termination measure. The latter is necessary once the
  1137 invariant proof rule for while is applied.
  1138 
  1139 * HOL: new (overloaded) notation for the set of elements below/above
  1140 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1141 
  1142 * HOL: theorems impI, allI, ballI bound as "strip";
  1143 
  1144 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1145 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1146 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1147 
  1148 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1149 
  1150 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1151 main HOL, but was unused);
  1152 
  1153 * HOL: fewer consts declared as global (e.g. have to refer to
  1154 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1155 
  1156 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1157 in case of overlap with user translations (e.g. judgements over
  1158 tuples); (note that the underlying logical represenation is still
  1159 bogus);
  1160 
  1161 
  1162 *** ZF ***
  1163 
  1164 * ZF: simplification automatically cancels common terms in arithmetic
  1165 expressions over nat and int;
  1166 
  1167 * ZF: new treatment of nat to minimize type-checking: all operators
  1168 coerce their operands to a natural number using the function natify,
  1169 making the algebraic laws unconditional;
  1170 
  1171 * ZF: as above, for int: operators coerce their operands to an integer
  1172 using the function intify;
  1173 
  1174 * ZF: the integer library now contains many of the usual laws for the
  1175 orderings, including $<=, and monotonicity laws for $+ and $*;
  1176 
  1177 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1178 simplification;
  1179 
  1180 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1181 to the simplifier and classical reasoner simultaneously;
  1182 
  1183 
  1184 *** General ***
  1185 
  1186 * Provers: blast_tac now handles actual object-logic rules as
  1187 assumptions; note that auto_tac uses blast_tac internally as well;
  1188 
  1189 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1190 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1191 
  1192 * Provers: delrules now handles destruct rules as well (no longer need
  1193 explicit make_elim);
  1194 
  1195 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1196   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1197 use instead the strong form,
  1198   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1199 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1200 from destruct-rules;
  1201 
  1202 * Provers: Simplifier.easy_setup provides a fast path to basic
  1203 Simplifier setup for new object-logics;
  1204 
  1205 * Pure: AST translation rules no longer require constant head on LHS;
  1206 
  1207 * Pure: improved name spaces: ambiguous output is qualified; support
  1208 for hiding of names;
  1209 
  1210 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1211 XSYMBOL_HOME; no longer need to do manual configuration in most
  1212 situations;
  1213 
  1214 * system: compression of ML heaps images may now be controlled via -c
  1215 option of isabelle and isatool usedir (currently only observed by
  1216 Poly/ML);
  1217 
  1218 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1219 useful for remote X11);
  1220 
  1221 * system: provide TAGS file for Isabelle sources;
  1222 
  1223 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1224 order;
  1225 
  1226 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1227 timing flag supersedes proof_timing and Toplevel.trace;
  1228 
  1229 * ML: new combinators |>> and |>>> for incremental transformations
  1230 with secondary results (e.g. certain theory extensions):
  1231 
  1232 * ML: PureThy.add_defs gets additional argument to indicate potential
  1233 overloading (usually false);
  1234 
  1235 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1236 results;
  1237 
  1238 
  1239 
  1240 New in Isabelle99 (October 1999)
  1241 --------------------------------
  1242 
  1243 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1244 
  1245 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1246 are no longer simplified.  (This allows the simplifier to unfold recursive
  1247 functional programs.)  To restore the old behaviour, declare
  1248 
  1249     Delcongs [if_weak_cong];
  1250 
  1251 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1252 complement;
  1253 
  1254 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1255 
  1256 * HOL/datatype: mutual_induct_tac no longer exists --
  1257   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1258 
  1259 * HOL/typedef: fixed type inference for representing set; type
  1260 arguments now have to occur explicitly on the rhs as type constraints;
  1261 
  1262 * ZF: The con_defs part of an inductive definition may no longer refer
  1263 to constants declared in the same theory;
  1264 
  1265 * HOL, ZF: the function mk_cases, generated by the inductive
  1266 definition package, has lost an argument.  To simplify its result, it
  1267 uses the default simpset instead of a supplied list of theorems.
  1268 
  1269 * HOL/List: the constructors of type list are now Nil and Cons;
  1270 
  1271 * Simplifier: the type of the infix ML functions
  1272         setSSolver addSSolver setSolver addSolver
  1273 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1274 for packaging solvers. A solver is created via
  1275         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1276 where the string argument is only a comment.
  1277 
  1278 
  1279 *** Proof tools ***
  1280 
  1281 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1282 decision procedure for linear arithmetic. Currently it is used for
  1283 types `nat', `int', and `real' in HOL (see below); it can, should and
  1284 will be instantiated for other types and logics as well.
  1285 
  1286 * The simplifier now accepts rewrite rules with flexible heads, eg
  1287      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1288   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1289   matching.
  1290 
  1291 
  1292 *** General ***
  1293 
  1294 * New Isabelle/Isar subsystem provides an alternative to traditional
  1295 tactical theorem proving; together with the ProofGeneral/isar user
  1296 interface it offers an interactive environment for developing human
  1297 readable proof documents (Isar == Intelligible semi-automated
  1298 reasoning); for further information see isatool doc isar-ref,
  1299 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1300 
  1301 * improved and simplified presentation of theories: better HTML markup
  1302 (including colors), graph views in several sizes; isatool usedir now
  1303 provides a proper interface for user theories (via -P option); actual
  1304 document preparation based on (PDF)LaTeX is available as well (for
  1305 new-style theories only); see isatool doc system for more information;
  1306 
  1307 * native support for Proof General, both for classic Isabelle and
  1308 Isabelle/Isar;
  1309 
  1310 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1311 using the graph browser tool;
  1312 
  1313 * Isabelle manuals now also available as PDF;
  1314 
  1315 * theory loader rewritten from scratch (may not be fully
  1316 bug-compatible); old loadpath variable has been replaced by show_path,
  1317 add_path, del_path, reset_path functions; new operations such as
  1318 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1319 isatool doc ref);
  1320 
  1321 * improved isatool install: option -k creates KDE application icon,
  1322 option -p DIR installs standalone binaries;
  1323 
  1324 * added ML_PLATFORM setting (useful for cross-platform installations);
  1325 more robust handling of platform specific ML images for SML/NJ;
  1326 
  1327 * the settings environment is now statically scoped, i.e. it is never
  1328 created again in sub-processes invoked from isabelle, isatool, or
  1329 Isabelle;
  1330 
  1331 * path element specification '~~' refers to '$ISABELLE_HOME';
  1332 
  1333 * in locales, the "assumes" and "defines" parts may be omitted if
  1334 empty;
  1335 
  1336 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1337 long arrows);
  1338 
  1339 * new print_mode "HTML";
  1340 
  1341 * new flag show_tags controls display of tags of theorems (which are
  1342 basically just comments that may be attached by some tools);
  1343 
  1344 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1345 mode and goal output format:
  1346 
  1347 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1348 244c244
  1349 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1350 ---
  1351 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1352 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1353 181c181
  1354 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1355 ---
  1356 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1357 
  1358 * function bind_thms stores lists of theorems (cf. bind_thm);
  1359 
  1360 * new shorthand tactics ftac, eatac, datac, fatac;
  1361 
  1362 * qed (and friends) now accept "" as result name; in that case the
  1363 theorem is not stored, but proper checks and presentation of the
  1364 result still apply;
  1365 
  1366 * theorem database now also indexes constants "Trueprop", "all",
  1367 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1368 
  1369 
  1370 *** HOL ***
  1371 
  1372 ** HOL arithmetic **
  1373 
  1374 * There are now decision procedures for linear arithmetic over nat and
  1375 int:
  1376 
  1377 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1378 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1379 are treated as atomic; subformulae not involving type `nat' or `int'
  1380 are ignored; quantified subformulae are ignored unless they are
  1381 positive universal or negative existential. The tactic has to be
  1382 invoked by hand and can be a little bit slow. In particular, the
  1383 running time is exponential in the number of occurrences of `min' and
  1384 `max', and `-' on `nat'.
  1385 
  1386 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1387 (negated) (in)equalities among the premises and the conclusion into
  1388 account (i.e. no compound formulae) and does not know about `min' and
  1389 `max', and `-' on `nat'. It is fast and is used automatically by the
  1390 simplifier.
  1391 
  1392 NB: At the moment, these decision procedures do not cope with mixed
  1393 nat/int formulae where the two parts interact, such as `m < n ==>
  1394 int(m) < int(n)'.
  1395 
  1396 * HOL/Numeral provides a generic theory of numerals (encoded
  1397 efficiently as bit strings); setup for types nat/int/real is in place;
  1398 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1399 int, existing theories and proof scripts may require a few additional
  1400 type constraints;
  1401 
  1402 * integer division and remainder can now be performed on constant
  1403 arguments;
  1404 
  1405 * many properties of integer multiplication, division and remainder
  1406 are now available;
  1407 
  1408 * An interface to the Stanford Validity Checker (SVC) is available through the
  1409 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1410 are proved automatically.  SVC must be installed separately, and its results
  1411 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1412 invocation of the underlying oracle).  For SVC see
  1413   http://verify.stanford.edu/SVC
  1414 
  1415 * IsaMakefile: the HOL-Real target now builds an actual image;
  1416 
  1417 
  1418 ** HOL misc **
  1419 
  1420 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1421 (in Isabelle/Isar) -- by Gertrud Bauer;
  1422 
  1423 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1424 analysis for assembly languages with subtypes;
  1425 
  1426 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1427 -- avoids syntactic ambiguities and treats state, transition, and
  1428 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1429 changed syntax and (many) tactics;
  1430 
  1431 * HOL/inductive: Now also handles more general introduction rules such
  1432   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1433   theorems are now maintained within the theory (maintained via the
  1434   "mono" attribute);
  1435 
  1436 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1437   (using function types) such as
  1438 
  1439   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1440 
  1441 * HOL/record: record_simproc (part of the default simpset) takes care
  1442 of selectors applied to updated records; record_split_tac is no longer
  1443 part of the default claset; update_defs may now be removed from the
  1444 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1445 
  1446   claset_ref () := claset() addSWrapper record_split_wrapper;
  1447   Delsimprocs [record_simproc]
  1448 
  1449 * HOL/typedef: fixed type inference for representing set; type
  1450 arguments now have to occur explicitly on the rhs as type constraints;
  1451 
  1452 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1453 names rather than an ML expression;
  1454 
  1455 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1456 supplied later.  Program schemes can be defined, such as
  1457     "While B C s = (if B s then While B C (C s) else s)"
  1458 where the well-founded relation can be chosen after B and C have been given.
  1459 
  1460 * HOL/List: the constructors of type list are now Nil and Cons;
  1461 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1462 course, ML tools referring to List.list.op # etc. have to be adapted;
  1463 
  1464 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1465 disabled by default; run isabelle with option -m HOL to get back to
  1466 the original Gordon/HOL-style output;
  1467 
  1468 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1469 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1470 
  1471 * HOL basic syntax simplified (more orthogonal): all variants of
  1472 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1473 Eps operator is provided as well: "SOME x. P[x]";
  1474 
  1475 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1476 
  1477 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1478 thus available for user theories;
  1479 
  1480 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1481 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1482 time;
  1483 
  1484 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1485 several times and then mp;
  1486 
  1487 
  1488 *** LK ***
  1489 
  1490 * the notation <<...>> is now available as a notation for sequences of
  1491 formulas;
  1492 
  1493 * the simplifier is now installed
  1494 
  1495 * the axiom system has been generalized (thanks to Soren Heilmann)
  1496 
  1497 * the classical reasoner now has a default rule database
  1498 
  1499 
  1500 *** ZF ***
  1501 
  1502 * new primrec section allows primitive recursive functions to be given
  1503 directly (as in HOL) over datatypes and the natural numbers;
  1504 
  1505 * new tactics induct_tac and exhaust_tac for induction (or case
  1506 analysis) over datatypes and the natural numbers;
  1507 
  1508 * the datatype declaration of type T now defines the recursor T_rec;
  1509 
  1510 * simplification automatically does freeness reasoning for datatype
  1511 constructors;
  1512 
  1513 * automatic type-inference, with AddTCs command to insert new
  1514 type-checking rules;
  1515 
  1516 * datatype introduction rules are now added as Safe Introduction rules
  1517 to the claset;
  1518 
  1519 * the syntax "if P then x else y" is now available in addition to
  1520 if(P,x,y);
  1521 
  1522 
  1523 *** Internal programming interfaces ***
  1524 
  1525 * tuned simplifier trace output; new flag debug_simp;
  1526 
  1527 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1528 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1529 
  1530 * AxClass.axclass_tac lost the theory argument;
  1531 
  1532 * tuned current_goals_markers semantics: begin / end goal avoids
  1533 printing empty lines;
  1534 
  1535 * removed prs and prs_fn hook, which was broken because it did not
  1536 include \n in its semantics, forcing writeln to add one
  1537 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1538 string -> unit if you really want to output text without newline;
  1539 
  1540 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1541 plain output, interface builders may have to enable 'isabelle_font'
  1542 mode to get Isabelle font glyphs as before;
  1543 
  1544 * refined token_translation interface; INCOMPATIBILITY: output length
  1545 now of type real instead of int;
  1546 
  1547 * theory loader actions may be traced via new ThyInfo.add_hook
  1548 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1549 your own database of information attached to *whole* theories -- as
  1550 opposed to intra-theory data slots offered via TheoryDataFun;
  1551 
  1552 * proper handling of dangling sort hypotheses (at last!);
  1553 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1554 extra sort hypotheses that can be witnessed from the type signature;
  1555 the force_strip_shyps flag is gone, any remaining shyps are simply
  1556 left in the theorem (with a warning issued by strip_shyps_warning);
  1557 
  1558 
  1559 
  1560 New in Isabelle98-1 (October 1998)
  1561 ----------------------------------
  1562 
  1563 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1564 
  1565 * several changes of automated proof tools;
  1566 
  1567 * HOL: major changes to the inductive and datatype packages, including
  1568 some minor incompatibilities of theory syntax;
  1569 
  1570 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1571 called `inj_on';
  1572 
  1573 * HOL: removed duplicate thms in Arith:
  1574   less_imp_add_less  should be replaced by  trans_less_add1
  1575   le_imp_add_le      should be replaced by  trans_le_add1
  1576 
  1577 * HOL: unary minus is now overloaded (new type constraints may be
  1578 required);
  1579 
  1580 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1581 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1582 now taken as an integer constant.
  1583 
  1584 * Pure: ML function 'theory_of' renamed to 'theory';
  1585 
  1586 
  1587 *** Proof tools ***
  1588 
  1589 * Simplifier:
  1590   1. Asm_full_simp_tac is now more aggressive.
  1591      1. It will sometimes reorient premises if that increases their power to
  1592         simplify.
  1593      2. It does no longer proceed strictly from left to right but may also
  1594         rotate premises to achieve further simplification.
  1595      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1596      old Asm_full_simp_tac in that it does not rotate premises.
  1597   2. The simplifier now knows a little bit about nat-arithmetic.
  1598 
  1599 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1600 allows for selected deletion of wrappers, by introduction of names for
  1601 wrapper functionals.  This implies that addbefore, addSbefore,
  1602 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1603 and that adding two tactics with the same name overwrites the first
  1604 one (emitting a warning).
  1605   type wrapper = (int -> tactic) -> (int -> tactic)
  1606   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1607   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1608   delWrapper, delSWrapper: claset *  string            -> claset
  1609   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1610 
  1611 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1612 semantics; addbefore now affects only the unsafe part of step_tac
  1613 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1614 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1615 by Force_tac;
  1616 
  1617 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1618 compWrapper; added safe wrapper (and access functions for it);
  1619 
  1620 * HOL/split_all_tac is now much faster and fails if there is nothing
  1621 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1622 and the names of the automatically generated variables have changed.
  1623 split_all_tac has moved within claset() from unsafe wrappers to safe
  1624 wrappers, which means that !!-bound variables are split much more
  1625 aggressively, and safe_tac and clarify_tac now split such variables.
  1626 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1627 Note: the same holds for record_split_tac, which does the job of
  1628 split_all_tac for record fields.
  1629 
  1630 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1631 permanently to the default simpset using Addsplits just like
  1632 Addsimps. They can be removed via Delsplits just like
  1633 Delsimps. Lower-case versions are also available.
  1634 
  1635 * HOL/Simplifier: The rule split_if is now part of the default
  1636 simpset. This means that the simplifier will eliminate all occurrences
  1637 of if-then-else in the conclusion of a goal. To prevent this, you can
  1638 either remove split_if completely from the default simpset by
  1639 `Delsplits [split_if]' or remove it in a specific call of the
  1640 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1641 other case splitting rules to/from the default simpset: every datatype
  1642 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1643 t is the name of the datatype).
  1644 
  1645 * Classical reasoner / Simplifier combination: new force_tac (and
  1646 derivatives Force_tac, force) combines rewriting and classical
  1647 reasoning (and whatever other tools) similarly to auto_tac, but is
  1648 aimed to solve the given subgoal completely.
  1649 
  1650 
  1651 *** General ***
  1652 
  1653 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1654 and `goalw': the theory is no longer needed as an explicit argument -
  1655 the current theory context is used; assumptions are no longer returned
  1656 at the ML-level unless one of them starts with ==> or !!; it is
  1657 recommended to convert to these new commands using isatool fixgoal
  1658 (backup your sources first!);
  1659 
  1660 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1661 the current theory context, and 'theory' to lookup stored theories;
  1662 
  1663 * new theory section 'locale' for declaring constants, assumptions and
  1664 definitions that have local scope;
  1665 
  1666 * new theory section 'nonterminals' for purely syntactic types;
  1667 
  1668 * new theory section 'setup' for generic ML setup functions
  1669 (e.g. package initialization);
  1670 
  1671 * the distribution now includes Isabelle icons: see
  1672 lib/logo/isabelle-{small,tiny}.xpm;
  1673 
  1674 * isatool install - install binaries with absolute references to
  1675 ISABELLE_HOME/bin;
  1676 
  1677 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1678 
  1679 * print mode 'emacs' reserved for Isamode;
  1680 
  1681 * support multiple print (ast) translations per constant name;
  1682 
  1683 * theorems involving oracles are now printed with a suffixed [!];
  1684 
  1685 
  1686 *** HOL ***
  1687 
  1688 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1689 
  1690 * HOL/inductive package reorganized and improved: now supports mutual
  1691 definitions such as
  1692 
  1693   inductive EVEN ODD
  1694     intrs
  1695       null "0 : EVEN"
  1696       oddI "n : EVEN ==> Suc n : ODD"
  1697       evenI "n : ODD ==> Suc n : EVEN"
  1698 
  1699 new theorem list "elims" contains an elimination rule for each of the
  1700 recursive sets; inductive definitions now handle disjunctive premises
  1701 correctly (also ZF);
  1702 
  1703 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1704 "mutual_induct" no longer exists - the induction rule is always
  1705 contained in "induct";
  1706 
  1707 
  1708 * HOL/datatype package re-implemented and greatly improved: now
  1709 supports mutually recursive datatypes such as
  1710 
  1711   datatype
  1712     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1713             | SUM ('a aexp) ('a aexp)
  1714             | DIFF ('a aexp) ('a aexp)
  1715             | NUM 'a
  1716   and
  1717     'a bexp = LESS ('a aexp) ('a aexp)
  1718             | AND ('a bexp) ('a bexp)
  1719             | OR ('a bexp) ('a bexp)
  1720 
  1721 as well as indirectly recursive datatypes such as
  1722 
  1723   datatype
  1724     ('a, 'b) term = Var 'a
  1725                   | App 'b ((('a, 'b) term) list)
  1726 
  1727 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1728 induction on mutually / indirectly recursive datatypes.
  1729 
  1730 Primrec equations are now stored in theory and can be accessed via
  1731 <function_name>.simps.
  1732 
  1733 INCOMPATIBILITIES:
  1734 
  1735   - Theories using datatypes must now have theory Datatype as an
  1736     ancestor.
  1737   - The specific <typename>.induct_tac no longer exists - use the
  1738     generic induct_tac instead.
  1739   - natE has been renamed to nat.exhaust - use exhaust_tac
  1740     instead of res_inst_tac ... natE. Note that the variable
  1741     names in nat.exhaust differ from the names in natE, this
  1742     may cause some "fragile" proofs to fail.
  1743   - The theorems split_<typename>_case and split_<typename>_case_asm
  1744     have been renamed to <typename>.split and <typename>.split_asm.
  1745   - Since default sorts of type variables are now handled correctly,
  1746     some datatype definitions may have to be annotated with explicit
  1747     sort constraints.
  1748   - Primrec definitions no longer require function name and type
  1749     of recursive argument.
  1750 
  1751 Consider using isatool fixdatatype to adapt your theories and proof
  1752 scripts to the new package (backup your sources first!).
  1753 
  1754 
  1755 * HOL/record package: considerably improved implementation; now
  1756 includes concrete syntax for record types, terms, updates; theorems
  1757 for surjective pairing and splitting !!-bound record variables; proof
  1758 support is as follows:
  1759 
  1760   1) standard conversions (selectors or updates applied to record
  1761 constructor terms) are part of the standard simpset;
  1762 
  1763   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1764 made part of standard simpset and claset via addIffs;
  1765 
  1766   3) a tactic for record field splitting (record_split_tac) is part of
  1767 the standard claset (addSWrapper);
  1768 
  1769 To get a better idea about these rules you may retrieve them via
  1770 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1771 the name of your record type.
  1772 
  1773 The split tactic 3) conceptually simplifies by the following rule:
  1774 
  1775   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1776 
  1777 Thus any record variable that is bound by meta-all will automatically
  1778 blow up into some record constructor term, consequently the
  1779 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1780 solve record problems automatically.
  1781 
  1782 
  1783 * reorganized the main HOL image: HOL/Integ and String loaded by
  1784 default; theory Main includes everything;
  1785 
  1786 * automatic simplification of integer sums and comparisons, using cancellation;
  1787 
  1788 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1789 
  1790 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1791 
  1792 * many new identities for unions, intersections, set difference, etc.;
  1793 
  1794 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1795 called split_if, split_split, split_sum_case and split_nat_case (to go
  1796 with add/delsplits);
  1797 
  1798 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1799 (?x::unit) = (); this is made part of the default simpset, which COULD
  1800 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1801 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1802 unit_abs_eta_conv is added in order to counter the effect of
  1803 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1804 %u.f();
  1805 
  1806 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1807 makes more sense);
  1808 
  1809 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1810   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1811   disjointness reasoning but breaking a few old proofs.
  1812 
  1813 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1814 to 'converse' from 'inverse' (for compatibility with ZF and some
  1815 literature);
  1816 
  1817 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1818 the well-founded relation;
  1819 
  1820 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1821     Compl A.  The "Compl" syntax remains available as input syntax for this
  1822     release ONLY.
  1823 
  1824 * HOL/Update: new theory of function updates:
  1825     f(a:=b) == %x. if x=a then b else f x
  1826 may also be iterated as in f(a:=b,c:=d,...);
  1827 
  1828 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1829 
  1830 * HOL/List:
  1831   - new function list_update written xs[i:=v] that updates the i-th
  1832     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1833   - new function `upt' written [i..j(] which generates the list
  1834     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1835     bound write [i..j], which is a shorthand for [i..j+1(].
  1836   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1837 
  1838 * HOL/Arith:
  1839   - removed 'pred' (predecessor) function;
  1840   - generalized some theorems about n-1;
  1841   - many new laws about "div" and "mod";
  1842   - new laws about greatest common divisors (see theory ex/Primes);
  1843 
  1844 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1845 instead of "inverse";
  1846 
  1847 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1848   of the multiset ordering;
  1849 
  1850 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1851   (not included by default);
  1852 
  1853 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1854 
  1855 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1856   programs, i.e. different program variables may have different types.
  1857 
  1858 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1859   [previously, this check worked only if the rewrite rule was unconditional]
  1860   Now rew can involve either definitions or equalities (either == or =).
  1861 
  1862 
  1863 *** ZF ***
  1864 
  1865 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1866   only the theorems proved on ZF.ML;
  1867 
  1868 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1869   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1870   disjointness reasoning but breaking a few old proofs.
  1871 
  1872 * ZF/Update: new theory of function updates
  1873     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1874   may also be iterated as in f(a:=b,c:=d,...);
  1875 
  1876 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1877 
  1878 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1879   [previously, this check worked only if the rewrite rule was unconditional]
  1880   Now rew can involve either definitions or equalities (either == or =).
  1881 
  1882 * case_tac provided for compatibility with HOL
  1883     (like the old excluded_middle_tac, but with subgoals swapped)
  1884 
  1885 
  1886 *** Internal programming interfaces ***
  1887 
  1888 * Pure: several new basic modules made available for general use, see
  1889 also src/Pure/README;
  1890 
  1891 * improved the theory data mechanism to support encapsulation (data
  1892 kind name replaced by private Object.kind, acting as authorization
  1893 key); new type-safe user interface via functor TheoryDataFun; generic
  1894 print_data function becomes basically useless;
  1895 
  1896 * removed global_names compatibility flag -- all theory declarations
  1897 are qualified by default;
  1898 
  1899 * module Pure/Syntax now offers quote / antiquote translation
  1900 functions (useful for Hoare logic etc. with implicit dependencies);
  1901 see HOL/ex/Antiquote for an example use;
  1902 
  1903 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1904 cterm -> thm;
  1905 
  1906 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1907 subgoal;
  1908 
  1909 * Display.print_goals function moved to Locale.print_goals;
  1910 
  1911 * standard print function for goals supports current_goals_markers
  1912 variable for marking begin of proof, end of proof, start of goal; the
  1913 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1914 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1915 for example;
  1916 
  1917 
  1918 
  1919 New in Isabelle98 (January 1998)
  1920 --------------------------------
  1921 
  1922 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1923 
  1924 * changed lexical syntax of terms / types: dots made part of long
  1925 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1926 
  1927 * simpset (and claset) reference variable replaced by functions
  1928 simpset / simpset_ref;
  1929 
  1930 * no longer supports theory aliases (via merge) and non-trivial
  1931 implicit merge of thms' signatures;
  1932 
  1933 * most internal names of constants changed due to qualified names;
  1934 
  1935 * changed Pure/Sequence interface (see Pure/seq.ML);
  1936 
  1937 
  1938 *** General Changes ***
  1939 
  1940 * hierachically structured name spaces (for consts, types, axms, thms
  1941 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1942 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1943 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1944 long_names for fully qualified output names; NOTE: ML programs
  1945 (special tactics, packages etc.) referring to internal names may have
  1946 to be adapted to cope with fully qualified names; in case of severe
  1947 backward campatibility problems try setting 'global_names' at compile
  1948 time to have enrything declared within a flat name space; one may also
  1949 fine tune name declarations in theories via the 'global' and 'local'
  1950 section;
  1951 
  1952 * reimplemented the implicit simpset and claset using the new anytype
  1953 data filed in signatures; references simpset:simpset ref etc. are
  1954 replaced by functions simpset:unit->simpset and
  1955 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1956 to patch your ML files accordingly;
  1957 
  1958 * HTML output now includes theory graph data for display with Java
  1959 applet or isatool browser; data generated automatically via isatool
  1960 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1961 
  1962 * defs may now be conditional; improved rewrite_goals_tac to handle
  1963 conditional equations;
  1964 
  1965 * defs now admits additional type arguments, using TYPE('a) syntax;
  1966 
  1967 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1968 creates a new theory node; implicit merge of thms' signatures is
  1969 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1970 transfer:theory->thm->thm in (rare) cases;
  1971 
  1972 * improved handling of draft signatures / theories; draft thms (and
  1973 ctyps, cterms) are automatically promoted to real ones;
  1974 
  1975 * slightly changed interfaces for oracles: admit many per theory, named
  1976 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1977 
  1978 * print_goals: optional output of const types (set show_consts and
  1979 show_types);
  1980 
  1981 * improved output of warnings (###) and errors (***);
  1982 
  1983 * subgoal_tac displays a warning if the new subgoal has type variables;
  1984 
  1985 * removed old README and Makefiles;
  1986 
  1987 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1988 
  1989 * removed obsolete init_pps and init_database;
  1990 
  1991 * deleted the obsolete tactical STATE, which was declared by
  1992     fun STATE tacfun st = tacfun st st;
  1993 
  1994 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1995 (which abbreviates $HOME);
  1996 
  1997 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1998 use isatool fixseq to adapt your ML programs (this works for fully
  1999 qualified references to the Sequence structure only!);
  2000 
  2001 * use_thy no longer requires writable current directory; it always
  2002 reloads .ML *and* .thy file, if either one is out of date;
  2003 
  2004 
  2005 *** Classical Reasoner ***
  2006 
  2007 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2008 tactics that use classical reasoning to simplify a subgoal without
  2009 splitting it into several subgoals;
  2010 
  2011 * Safe_tac: like safe_tac but uses the default claset;
  2012 
  2013 
  2014 *** Simplifier ***
  2015 
  2016 * added simplification meta rules:
  2017     (asm_)(full_)simplify: simpset -> thm -> thm;
  2018 
  2019 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2020 logics (again);
  2021 
  2022 * added prems argument to simplification procedures;
  2023 
  2024 * HOL, FOL, ZF: added infix function `addsplits':
  2025   instead of `<simpset> setloop (split_tac <thms>)'
  2026   you can simply write `<simpset> addsplits <thms>'
  2027 
  2028 
  2029 *** Syntax ***
  2030 
  2031 * TYPE('a) syntax for type reflection terms;
  2032 
  2033 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2034 
  2035 * pretty printer: changed order of mixfix annotation preference (again!);
  2036 
  2037 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2038 
  2039 
  2040 *** HOL ***
  2041 
  2042 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2043   with `addloop' of the simplifier to faciliate case splitting in premises.
  2044 
  2045 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2046 
  2047 * HOL/Auth: new protocol proofs including some for the Internet
  2048   protocol TLS;
  2049 
  2050 * HOL/Map: new theory of `maps' a la VDM;
  2051 
  2052 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2053 cancelling out common nat summands from =, <, <= (in)equalities, or
  2054 differences; simplification procedures nat_cancel_factor for
  2055 cancelling common factor from =, <, <= (in)equalities over natural
  2056 sums; nat_cancel contains both kinds of procedures, it is installed by
  2057 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2058 
  2059 * HOL/simplifier: terms of the form
  2060   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2061   are rewritten to
  2062   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2063   and those of the form
  2064   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2065   are rewritten to
  2066   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2067 
  2068 * HOL/datatype
  2069   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2070 
  2071   P(t_case f1 ... fn x) =
  2072      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2073         ...
  2074        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2075      )
  2076 
  2077   and a theorem `split_t_case_asm' of the form
  2078 
  2079   P(t_case f1 ... fn x) =
  2080     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2081         ...
  2082        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2083      )
  2084   which can be added to a simpset via `addsplits'. The existing theorems
  2085   expand_list_case and expand_option_case have been renamed to
  2086   split_list_case and split_option_case.
  2087 
  2088 * HOL/Arithmetic:
  2089   - `pred n' is automatically converted to `n-1'.
  2090     Users are strongly encouraged not to use `pred' any longer,
  2091     because it will disappear altogether at some point.
  2092   - Users are strongly encouraged to write "0 < n" rather than
  2093     "n ~= 0". Theorems and proof tools have been modified towards this
  2094     `standard'.
  2095 
  2096 * HOL/Lists:
  2097   the function "set_of_list" has been renamed "set" (and its theorems too);
  2098   the function "nth" now takes its arguments in the reverse order and
  2099   has acquired the infix notation "!" as in "xs!n".
  2100 
  2101 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2102 
  2103 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2104   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2105 
  2106 * HOL/record: extensible records with schematic structural subtyping
  2107 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2108 still lacks various theorems and concrete record syntax;
  2109 
  2110 
  2111 *** HOLCF ***
  2112 
  2113 * removed "axioms" and "generated by" sections;
  2114 
  2115 * replaced "ops" section by extended "consts" section, which is capable of
  2116   handling the continuous function space "->" directly;
  2117 
  2118 * domain package:
  2119   . proves theorems immediately and stores them in the theory,
  2120   . creates hierachical name space,
  2121   . now uses normal mixfix annotations (instead of cinfix...),
  2122   . minor changes to some names and values (for consistency),
  2123   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2124   . separator between mutual domain defs: changed "," to "and",
  2125   . improved handling of sort constraints;  now they have to
  2126     appear on the left-hand side of the equations only;
  2127 
  2128 * fixed LAM <x,y,zs>.b syntax;
  2129 
  2130 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2131 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2132 
  2133 
  2134 *** FOL and ZF ***
  2135 
  2136 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2137   with `addloop' of the simplifier to faciliate case splitting in premises.
  2138 
  2139 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2140 in HOL, they strip ALL and --> from proved theorems;
  2141 
  2142 
  2143 
  2144 New in Isabelle94-8 (May 1997)
  2145 ------------------------------
  2146 
  2147 *** General Changes ***
  2148 
  2149 * new utilities to build / run / maintain Isabelle etc. (in parts
  2150 still somewhat experimental); old Makefiles etc. still functional;
  2151 
  2152 * new 'Isabelle System Manual';
  2153 
  2154 * INSTALL text, together with ./configure and ./build scripts;
  2155 
  2156 * reimplemented type inference for greater efficiency, better error
  2157 messages and clean internal interface;
  2158 
  2159 * prlim command for dealing with lots of subgoals (an easier way of
  2160 setting goals_limit);
  2161 
  2162 
  2163 *** Syntax ***
  2164 
  2165 * supports alternative (named) syntax tables (parser and pretty
  2166 printer); internal interface is provided by add_modesyntax(_i);
  2167 
  2168 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2169 be used in conjunction with the Isabelle symbol font; uses the
  2170 "symbols" syntax table;
  2171 
  2172 * added token_translation interface (may translate name tokens in
  2173 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2174 the current print_mode); IMPORTANT: user print translation functions
  2175 are responsible for marking newly introduced bounds
  2176 (Syntax.mark_boundT);
  2177 
  2178 * token translations for modes "xterm" and "xterm_color" that display
  2179 names in bold, underline etc. or colors (which requires a color
  2180 version of xterm);
  2181 
  2182 * infixes may now be declared with names independent of their syntax;
  2183 
  2184 * added typed_print_translation (like print_translation, but may
  2185 access type of constant);
  2186 
  2187 
  2188 *** Classical Reasoner ***
  2189 
  2190 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2191 some limitations.  Blast_tac...
  2192   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2193   + ignores elimination rules that don't have the correct format
  2194         (the conclusion MUST be a formula variable)
  2195   + ignores types, which can make HOL proofs fail
  2196   + rules must not require higher-order unification, e.g. apply_type in ZF
  2197     [message "Function Var's argument not a bound variable" relates to this]
  2198   + its proof strategy is more general but can actually be slower
  2199 
  2200 * substitution with equality assumptions no longer permutes other
  2201 assumptions;
  2202 
  2203 * minor changes in semantics of addafter (now called addaltern); renamed
  2204 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2205 (and access functions for it);
  2206 
  2207 * improved combination of classical reasoner and simplifier:
  2208   + functions for handling clasimpsets
  2209   + improvement of addss: now the simplifier is called _after_ the
  2210     safe steps.
  2211   + safe variant of addss called addSss: uses safe simplifications
  2212     _during_ the safe steps. It is more complete as it allows multiple
  2213     instantiations of unknowns (e.g. with slow_tac).
  2214 
  2215 *** Simplifier ***
  2216 
  2217 * added interface for simplification procedures (functions that
  2218 produce *proven* rewrite rules on the fly, depending on current
  2219 redex);
  2220 
  2221 * ordering on terms as parameter (used for ordered rewriting);
  2222 
  2223 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2224 
  2225 * the solver is now split into a safe and an unsafe part.
  2226 This should be invisible for the normal user, except that the
  2227 functions setsolver and addsolver have been renamed to setSolver and
  2228 addSolver; added safe_asm_full_simp_tac;
  2229 
  2230 
  2231 *** HOL ***
  2232 
  2233 * a generic induction tactic `induct_tac' which works for all datatypes and
  2234 also for type `nat';
  2235 
  2236 * a generic case distinction tactic `exhaust_tac' which works for all
  2237 datatypes and also for type `nat';
  2238 
  2239 * each datatype comes with a function `size';
  2240 
  2241 * patterns in case expressions allow tuple patterns as arguments to
  2242 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2243 
  2244 * primrec now also works with type nat;
  2245 
  2246 * recdef: a new declaration form, allows general recursive functions to be
  2247 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2248 
  2249 * the constant for negation has been renamed from "not" to "Not" to
  2250 harmonize with FOL, ZF, LK, etc.;
  2251 
  2252 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2253 infinite lists;
  2254 
  2255 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2256 
  2257 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2258 problems in commutative rings, using axiomatic type classes for + and *;
  2259 
  2260 * more examples in HOL/MiniML and HOL/Auth;
  2261 
  2262 * more default rewrite rules for quantifiers, union/intersection;
  2263 
  2264 * a new constant `arbitrary == @x.False';
  2265 
  2266 * HOLCF/IOA replaces old HOL/IOA;
  2267 
  2268 * HOLCF changes: derived all rules and arities
  2269   + axiomatic type classes instead of classes
  2270   + typedef instead of faking type definitions
  2271   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2272   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2273   + eliminated the types void, one, tr
  2274   + use unit lift and bool lift (with translations) instead of one and tr
  2275   + eliminated blift from Lift3.thy (use Def instead of blift)
  2276   all eliminated rules are derived as theorems --> no visible changes ;
  2277 
  2278 
  2279 *** ZF ***
  2280 
  2281 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2282 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2283 as ZF_cs addSIs [equalityI];
  2284 
  2285 
  2286 
  2287 New in Isabelle94-7 (November 96)
  2288 ---------------------------------
  2289 
  2290 * allowing negative levels (as offsets) in prlev and choplev;
  2291 
  2292 * super-linear speedup for large simplifications;
  2293 
  2294 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2295 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2296 FAIL); can suppress it using the command Delsimps (ex_simps @
  2297 all_simps); De Morgan laws are also now included, by default;
  2298 
  2299 * improved printing of ==>  :  ~:
  2300 
  2301 * new object-logic "Sequents" adds linear logic, while replacing LK
  2302 and Modal (thanks to Sara Kalvala);
  2303 
  2304 * HOL/Auth: correctness proofs for authentication protocols;
  2305 
  2306 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2307 examples on HOL/Auth);
  2308 
  2309 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2310 the rewriter and classical reasoner simultaneously;
  2311 
  2312 * function uresult no longer returns theorems in "standard" format;
  2313 regain previous version by: val uresult = standard o uresult;
  2314 
  2315 
  2316 
  2317 New in Isabelle94-6
  2318 -------------------
  2319 
  2320 * oracles -- these establish an interface between Isabelle and trusted
  2321 external reasoners, which may deliver results as theorems;
  2322 
  2323 * proof objects (in particular record all uses of oracles);
  2324 
  2325 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2326 
  2327 * "constdefs" section in theory files;
  2328 
  2329 * "primrec" section (HOL) no longer requires names;
  2330 
  2331 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2332 
  2333 
  2334 
  2335 New in Isabelle94-5
  2336 -------------------
  2337 
  2338 * reduced space requirements;
  2339 
  2340 * automatic HTML generation from theories;
  2341 
  2342 * theory files no longer require "..." (quotes) around most types;
  2343 
  2344 * new examples, including two proofs of the Church-Rosser theorem;
  2345 
  2346 * non-curried (1994) version of HOL is no longer distributed;
  2347 
  2348 
  2349 
  2350 New in Isabelle94-4
  2351 -------------------
  2352 
  2353 * greatly reduced space requirements;
  2354 
  2355 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2356 
  2357 * searchable theorem database (see the section "Retrieving theorems" on
  2358 page 8 of the Reference Manual);
  2359 
  2360 * new examples, including Grabczewski's monumental case study of the
  2361 Axiom of Choice;
  2362 
  2363 * The previous version of HOL renamed to Old_HOL;
  2364 
  2365 * The new version of HOL (previously called CHOL) uses a curried syntax
  2366 for functions.  Application looks like f a b instead of f(a,b);
  2367 
  2368 * Mutually recursive inductive definitions finally work in HOL;
  2369 
  2370 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2371 translates to the operator "split";
  2372 
  2373 
  2374 
  2375 New in Isabelle94-3
  2376 -------------------
  2377 
  2378 * new infix operator, addss, allowing the classical reasoner to
  2379 perform simplification at each step of its search.  Example:
  2380         fast_tac (cs addss ss)
  2381 
  2382 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2383 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2384 look like (a,b) instead of <a,b>;
  2385 
  2386 * PLEASE NOTE: CHOL will eventually replace HOL!
  2387 
  2388 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2389 It translates to the operator "split".  A new theory of integers is available;
  2390 
  2391 * In ZF, integer numerals now denote two's-complement binary integers.
  2392 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2393 
  2394 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2395 of the Axiom of Choice;
  2396 
  2397 
  2398 
  2399 New in Isabelle94-2
  2400 -------------------
  2401 
  2402 * Significantly faster resolution;
  2403 
  2404 * the different sections in a .thy file can now be mixed and repeated
  2405 freely;
  2406 
  2407 * Database of theorems for FOL, HOL and ZF.  New
  2408 commands including qed, qed_goal and bind_thm store theorems in the database.
  2409 
  2410 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2411 a given theory (thms_of), or find out what theory a theorem was proved in
  2412 (theory_of_thm);
  2413 
  2414 * Bugs fixed in the inductive definition and datatype packages;
  2415 
  2416 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2417 and HOL_dup_cs obsolete;
  2418 
  2419 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2420 have been removed;
  2421 
  2422 * Simpler definition of function space in ZF;
  2423 
  2424 * new results about cardinal and ordinal arithmetic in ZF;
  2425 
  2426 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2427 types;
  2428 
  2429 
  2430 $Id$