NEWS
author kleing
Tue Jul 29 13:32:16 2003 +0200 (2003-07-29)
changeset 14136 9b7a62788dac
parent 14119 fb9c392644a1
child 14171 0cab06e3bbd0
permissions -rw-r--r--
opened new section for next Isabelle release
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** HOL ***
     8 
     9 * 'specification' command added, allowing for definition by
    10 specification.
    11 
    12 
    13 New in Isabelle2003 (May 2003)
    14 --------------------------------
    15 
    16 *** General ***
    17 
    18 * Provers/simplifier:
    19 
    20   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
    21     Assumptions are now subject to complete mutual simplification,
    22     not just from left to right. The simplifier now preserves
    23     the order of assumptions.
    24 
    25     Potential INCOMPATIBILITY:
    26 
    27     -- simp sometimes diverges where the old version did
    28        not, e.g. invoking simp on the goal
    29 
    30         [| P (f x); y = x; f x = f y |] ==> Q
    31 
    32        now gives rise to the infinite reduction sequence
    33 
    34         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
    35 
    36        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
    37        kind of problem.
    38 
    39     -- Tactics combining classical reasoner and simplification (such as auto)
    40        are also affected by this change, because many of them rely on
    41        simp. They may sometimes diverge as well or yield a different numbers
    42        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
    43        in case of problems. Sometimes subsequent calls to the classical
    44        reasoner will fail because a preceeding call to the simplifier too
    45        eagerly simplified the goal, e.g. deleted redundant premises.
    46 
    47   - The simplifier trace now shows the names of the applied rewrite rules
    48 
    49   - You can limit the number of recursive invocations of the simplifier
    50     during conditional rewriting (where the simplifie tries to solve the
    51     conditions before applying the rewrite rule):
    52     ML "simp_depth_limit := n"
    53     where n is an integer. Thus you can force termination where previously
    54     the simplifier would diverge.
    55 
    56   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
    57 
    58   - No longer aborts on failed congruence proof.  Instead, the
    59     congruence is ignored.
    60 
    61 * Pure: New generic framework for extracting programs from constructive
    62   proofs. See HOL/Extraction.thy for an example instantiation, as well
    63   as HOL/Extraction for some case studies.
    64 
    65 * Pure: The main goal of the proof state is no longer shown by default, only
    66 the subgoals. This behaviour is controlled by a new flag.
    67    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
    68 (ML: Proof.show_main_goal).
    69 
    70 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
    71 rules whose conclusion matches subgoal 1:
    72       PG menu: Isabelle/Isar -> Show me -> matching rules
    73 The rules are ordered by how closely they match the subgoal.
    74 In particular, rules that solve a subgoal outright are displayed first
    75 (or rather last, the way they are printed).
    76 (ML: ProofGeneral.print_intros())
    77 
    78 * Pure: New flag trace_unify_fail causes unification to print
    79 diagnostic information (PG: in trace buffer) when it fails. This is
    80 useful for figuring out why single step proofs like rule, erule or
    81 assumption failed.
    82 
    83 * Pure: Locale specifications now produce predicate definitions
    84 according to the body of text (covering assumptions modulo local
    85 definitions); predicate "loc_axioms" covers newly introduced text,
    86 while "loc" is cumulative wrt. all included locale expressions; the
    87 latter view is presented only on export into the global theory
    88 context; potential INCOMPATIBILITY, use "(open)" option to fall back
    89 on the old view without predicates;
    90 
    91 * Pure: predefined locales "var" and "struct" are useful for sharing
    92 parameters (as in CASL, for example); just specify something like
    93 ``var x + var y + struct M'' as import;
    94 
    95 * Pure: improved thms_containing: proper indexing of facts instead of
    96 raw theorems; check validity of results wrt. current name space;
    97 include local facts of proof configuration (also covers active
    98 locales), cover fixed variables in index; may use "_" in term
    99 specification; an optional limit for the number of printed facts may
   100 be given (the default is 40);
   101 
   102 * Pure: disallow duplicate fact bindings within new-style theory files
   103 (batch-mode only);
   104 
   105 * Provers: improved induct method: assumptions introduced by case
   106 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   107 the goal statement); "foo" still refers to all facts collectively;
   108 
   109 * Provers: the function blast.overloaded has been removed: all constants
   110 are regarded as potentially overloaded, which improves robustness in exchange
   111 for slight decrease in efficiency;
   112 
   113 * Provers/linorder: New generic prover for transitivity reasoning over
   114 linear orders.  Note: this prover is not efficient!
   115 
   116 * Isar: preview of problems to finish 'show' now produce an error
   117 rather than just a warning (in interactive mode);
   118 
   119 
   120 *** HOL ***
   121 
   122 * arith(_tac)
   123 
   124  - Produces a counter example if it cannot prove a goal.
   125    Note that the counter example may be spurious if the goal is not a formula
   126    of quantifier-free linear arithmetic.
   127    In ProofGeneral the counter example appears in the trace buffer.
   128 
   129  - Knows about div k and mod k where k is a numeral of type nat or int.
   130 
   131  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   132    linear arithmetic fails. This takes account of quantifiers and divisibility.
   133    Presburger arithmetic can also be called explicitly via presburger(_tac). 
   134 
   135 * simp's arithmetic capabilities have been enhanced a bit: it now
   136 takes ~= in premises into account (by performing a case split);
   137 
   138 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   139 are distributed over a sum of terms;
   140 
   141 * New tactic "trans_tac" and method "trans" instantiate
   142 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   143 "<=", "<" and "="). 
   144 
   145 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main 
   146 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   147 
   148 * 'typedef' command has new option "open" to suppress the set
   149 definition;
   150 
   151 * functions Min and Max on finite sets have been introduced (theory
   152 Finite_Set);
   153 
   154 * attribute [symmetric] now works for relations as well; it turns
   155 (x,y) : R^-1 into (y,x) : R, and vice versa;
   156 
   157 * induct over a !!-quantified statement (say !!x1..xn):
   158   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   159 
   160 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   161 %x. None. Warning: empty_def now refers to the previously hidden definition
   162 of the empty set.
   163 
   164 * Algebra: formalization of classical algebra.  Intended as base for
   165 any algebraic development in Isabelle.  Currently covers group theory
   166 (up to Sylow's theorem) and ring theory (Universal Property of
   167 Univariate Polynomials).  Contributions welcome;
   168 
   169 * GroupTheory: deleted, since its material has been moved to Algebra;
   170 
   171 * Complex: new directory of the complex numbers with numeric constants, 
   172 nonstandard complex numbers, and some complex analysis, standard and 
   173 nonstandard (Jacques Fleuriot);
   174 
   175 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   176 
   177 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques 
   178 Fleuriot);
   179 
   180 * Real/HahnBanach: updated and adapted to locales;
   181 
   182 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   183 Gray and Kramer);
   184 
   185 * UNITY: added the Meier-Sanders theory of progress sets;
   186 
   187 * MicroJava: bytecode verifier and lightweight bytecode verifier
   188 as abstract algorithms, instantiated to the JVM;
   189 
   190 * Bali: Java source language formalization. Type system, operational
   191 semantics, axiomatic semantics. Supported language features:
   192 classes, interfaces, objects,virtual methods, static methods,
   193 static/instance fields, arrays, access modifiers, definite
   194 assignment, exceptions.
   195 
   196 
   197 *** ZF ***
   198 
   199 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   200 universe, etc.);
   201 
   202 * Main ZF: virtually all theories converted to new-style format;
   203 
   204 
   205 *** ML ***
   206 
   207 * Pure: Tactic.prove provides sane interface for internal proofs;
   208 omits the infamous "standard" operation, so this is more appropriate
   209 than prove_goalw_cterm in many situations (e.g. in simprocs);
   210 
   211 * Pure: improved error reporting of simprocs;
   212 
   213 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   214 up simprocs;
   215 
   216 
   217 *** Document preparation ***
   218 
   219 * uses \par instead of \\ for line breaks in theory text. This may
   220 shift some page breaks in large documents. To get the old behaviour
   221 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   222 
   223 * minimized dependencies of isabelle.sty and isabellesym.sty on 
   224 other packages
   225 
   226 * \<euro> now needs package babel/greek instead of marvosym (which
   227 broke \Rightarrow)
   228 
   229 * normal size for \<zero>...\<nine> (uses \mathbf instead of 
   230 textcomp package)
   231 
   232 
   233 New in Isabelle2002 (March 2002)
   234 --------------------------------
   235 
   236 *** Document preparation ***
   237 
   238 * greatly simplified document preparation setup, including more
   239 graceful interpretation of isatool usedir -i/-d/-D options, and more
   240 instructive isatool mkdir; users should basically be able to get
   241 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   242 users may run a separate document processing stage manually like this:
   243 "isatool usedir -D output HOL Test && isatool document Test/output";
   244 
   245 * theory dependency graph may now be incorporated into documents;
   246 isatool usedir -g true will produce session_graph.eps/.pdf for use
   247 with \includegraphics of LaTeX;
   248 
   249 * proper spacing of consecutive markup elements, especially text
   250 blocks after section headings;
   251 
   252 * support bold style (for single symbols only), input syntax is like
   253 this: "\<^bold>\<alpha>" or "\<^bold>A";
   254 
   255 * \<bullet> is now output as bold \cdot by default, which looks much
   256 better in printed text;
   257 
   258 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   259 note that these symbols are currently unavailable in Proof General /
   260 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   261 
   262 * isatool latex no longer depends on changed TEXINPUTS, instead
   263 isatool document copies the Isabelle style files to the target
   264 location;
   265 
   266 
   267 *** Isar ***
   268 
   269 * Pure/Provers: improved proof by cases and induction;
   270   - 'case' command admits impromptu naming of parameters (such as
   271     "case (Suc n)");
   272   - 'induct' method divinates rule instantiation from the inductive
   273     claim; no longer requires excessive ?P bindings for proper
   274     instantiation of cases;
   275   - 'induct' method properly enumerates all possibilities of set/type
   276     rules; as a consequence facts may be also passed through *type*
   277     rules without further ado;
   278   - 'induct' method now derives symbolic cases from the *rulified*
   279     rule (before it used to rulify cases stemming from the internal
   280     atomized version); this means that the context of a non-atomic
   281     statement becomes is included in the hypothesis, avoiding the
   282     slightly cumbersome show "PROP ?case" form;
   283   - 'induct' may now use elim-style induction rules without chaining
   284     facts, using ``missing'' premises from the goal state; this allows
   285     rules stemming from inductive sets to be applied in unstructured
   286     scripts, while still benefitting from proper handling of non-atomic
   287     statements; NB: major inductive premises need to be put first, all
   288     the rest of the goal is passed through the induction;
   289   - 'induct' proper support for mutual induction involving non-atomic
   290     rule statements (uses the new concept of simultaneous goals, see
   291     below);
   292   - append all possible rule selections, but only use the first
   293     success (no backtracking);
   294   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   295   - undeclared rule case names default to numbers 1, 2, 3, ...;
   296   - added 'print_induct_rules' (covered by help item in recent Proof
   297     General versions);
   298   - moved induct/cases attributes to Pure, methods to Provers;
   299   - generic method setup instantiated for FOL and HOL;
   300 
   301 * Pure: support multiple simultaneous goal statements, for example
   302 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   303 meta-level mechanism, this acts as if several individual goals had
   304 been stated separately; in particular common proof methods need to be
   305 repeated in order to cover all claims; note that a single elimination
   306 step is *not* sufficient to establish the two conjunctions, so this
   307 fails:
   308 
   309   assume "A & B" then have A and B ..   (*".." fails*)
   310 
   311 better use "obtain" in situations as above; alternative refer to
   312 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   313 
   314 * Pure: proper integration with ``locales''; unlike the original
   315 version by Florian Kammüller, Isar locales package high-level proof
   316 contexts rather than raw logical ones (e.g. we admit to include
   317 attributes everywhere); operations on locales include merge and
   318 rename; support for implicit arguments (``structures''); simultaneous
   319 type-inference over imports and text; see also HOL/ex/Locales.thy for
   320 some examples;
   321 
   322 * Pure: the following commands have been ``localized'', supporting a
   323 target locale specification "(in name)": 'lemma', 'theorem',
   324 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   325 stored both within the locale and at the theory level (exported and
   326 qualified by the locale name);
   327 
   328 * Pure: theory goals may now be specified in ``long'' form, with
   329 ad-hoc contexts consisting of arbitrary locale elements. for example
   330 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   331 definitions may be given, too); the result is a meta-level rule with
   332 the context elements being discharged in the obvious way;
   333 
   334 * Pure: new proof command 'using' allows to augment currently used
   335 facts after a goal statement ('using' is syntactically analogous to
   336 'apply', but acts on the goal's facts only); this allows chained facts
   337 to be separated into parts given before and after a claim, as in
   338 ``from a and b have C using d and e <proof>'';
   339 
   340 * Pure: renamed "antecedent" case to "rule_context";
   341 
   342 * Pure: new 'judgment' command records explicit information about the
   343 object-logic embedding (used by several tools internally); no longer
   344 use hard-wired "Trueprop";
   345 
   346 * Pure: added 'corollary' command;
   347 
   348 * Pure: fixed 'token_translation' command;
   349 
   350 * Pure: removed obsolete 'exported' attribute;
   351 
   352 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   353 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   354 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   355 
   356 * Pure: method 'atomize' presents local goal premises as object-level
   357 statements (atomic meta-level propositions); setup controlled via
   358 rewrite rules declarations of 'atomize' attribute; example
   359 application: 'induct' method with proper rule statements in improper
   360 proof *scripts*;
   361 
   362 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   363 now consider the syntactic context of assumptions, giving a better
   364 chance to get type-inference of the arguments right (this is
   365 especially important for locales);
   366 
   367 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   368 mode;
   369 
   370 * Pure/obtain: the formal conclusion "thesis", being marked as
   371 ``internal'', may no longer be reference directly in the text;
   372 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   373 situations;
   374 
   375 * Pure: generic 'sym' attribute which declares a rule both as pure
   376 'elim?' and for the 'symmetric' operation;
   377 
   378 * Pure: marginal comments ``--'' may now occur just anywhere in the
   379 text; the fixed correlation with particular command syntax has been
   380 discontinued;
   381 
   382 * Pure: new method 'rules' is particularly well-suited for proof
   383 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   384 but often produces more compact proof terms with less detours;
   385 
   386 * Pure/Provers/classical: simplified integration with pure rule
   387 attributes and methods; the classical "intro?/elim?/dest?"
   388 declarations coincide with the pure ones; the "rule" method no longer
   389 includes classically swapped intros; "intro" and "elim" methods no
   390 longer pick rules from the context; also got rid of ML declarations
   391 AddXIs/AddXEs/AddXDs; all of this has some potential for
   392 INCOMPATIBILITY;
   393 
   394 * Provers/classical: attribute 'swapped' produces classical inversions
   395 of introduction rules;
   396 
   397 * Provers/simplifier: 'simplified' attribute may refer to explicit
   398 rules instead of full simplifier context; 'iff' attribute handles
   399 conditional rules;
   400 
   401 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   402 
   403 * HOL: 'recdef' now fails on unfinished automated proofs, use
   404 "(permissive)" option to recover old behavior;
   405 
   406 * HOL: 'inductive' no longer features separate (collective) attributes
   407 for 'intros' (was found too confusing);
   408 
   409 * HOL: properly declared induction rules less_induct and
   410 wf_induct_rule;
   411 
   412 
   413 *** HOL ***
   414 
   415 * HOL: moved over to sane numeral syntax; the new policy is as
   416 follows:
   417 
   418   - 0 and 1 are polymorphic constants, which are defined on any
   419   numeric type (nat, int, real etc.);
   420 
   421   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   422   binary representation internally;
   423 
   424   - type nat has special constructor Suc, and generally prefers Suc 0
   425   over 1::nat and Suc (Suc 0) over 2::nat;
   426 
   427 This change may cause significant problems of INCOMPATIBILITY; here
   428 are some hints on converting existing sources:
   429 
   430   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   431   entities, so expressions involving "-" (unary or binary minus) need
   432   to be spaced properly;
   433 
   434   - existing occurrences of "1" may need to be constraint "1::nat" or
   435   even replaced by Suc 0; similar for old "2";
   436 
   437   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   438 
   439   - remove all special provisions on numerals in proofs;
   440 
   441 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   442 representation (depends on bin_arith_simps in the default context);
   443 
   444 * HOL: symbolic syntax for x^2 (numeral 2);
   445 
   446 * HOL: the class of all HOL types is now called "type" rather than
   447 "term"; INCOMPATIBILITY, need to adapt references to this type class
   448 in axclass/classes, instance/arities, and (usually rare) occurrences
   449 in typings (of consts etc.); internally the class is called
   450 "HOL.type", ML programs should refer to HOLogic.typeS;
   451 
   452 * HOL/record package improvements:
   453   - new derived operations "fields" to build a partial record section,
   454     "extend" to promote a fixed record to a record scheme, and
   455     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   456     declared as simp by default;
   457   - shared operations ("more", "fields", etc.) now need to be always
   458     qualified) --- potential INCOMPATIBILITY;
   459   - removed "make_scheme" operations (use "make" with "extend") --
   460     INCOMPATIBILITY;
   461   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   462   - provides cases/induct rules for use with corresponding Isar
   463     methods (for concrete records, record schemes, concrete more
   464     parts, and schematic more parts -- in that order);
   465   - internal definitions directly based on a light-weight abstract
   466     theory of product types over typedef rather than datatype;
   467 
   468 * HOL: generic code generator for generating executable ML code from
   469 specifications; specific support for HOL constructs such as inductive
   470 datatypes and sets, as well as recursive functions; can be invoked
   471 via 'generate_code' theory section;
   472 
   473 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   474 
   475 * HOL: consolidated and renamed several theories.  In particular:
   476 	Ord.thy has been absorbed into HOL.thy
   477 	String.thy has been absorbed into List.thy
   478  
   479 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   480 (beware of argument permutation!);
   481 
   482 * HOL: linorder_less_split superseded by linorder_cases;
   483 
   484 * HOL/List: "nodups" renamed to "distinct";
   485 
   486 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   487 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   488   - Ex_def has changed, now need to use some_eq_ex
   489 
   490 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   491 in this (rare) case use:
   492 
   493   delSWrapper "split_all_tac"
   494   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   495 
   496 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   497 MAY FAIL;
   498 
   499 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   500 Isabelle's type classes, ^ on functions and relations has too general
   501 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   502 necessary to attach explicit type constraints;
   503 
   504 * HOL/Relation: the prefix name of the infix "O" has been changed from
   505 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   506 renamed accordingly (eg "compI" -> "rel_compI").
   507 
   508 * HOL: syntax translations now work properly with numerals and records
   509 expressions;
   510 
   511 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   512 of "lam" -- INCOMPATIBILITY;
   513 
   514 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   515 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   516 renamed "Product_Type.unit";
   517 
   518 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   519 
   520 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   521 the "cases" method);
   522 
   523 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   524 Florian Kammüller);
   525 
   526 * HOL/IMP: updated and converted to new-style theory format; several
   527 parts turned into readable document, with proper Isar proof texts and
   528 some explanations (by Gerwin Klein);
   529 
   530 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   531 
   532 * HOL-Hyperreal is now a logic image;
   533 
   534 
   535 *** HOLCF ***
   536 
   537 * Isar: consts/constdefs supports mixfix syntax for continuous
   538 operations;
   539 
   540 * Isar: domain package adapted to new-style theory format, e.g. see
   541 HOLCF/ex/Dnat.thy;
   542 
   543 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   544 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   545 lift.induct_tac, always use UU instead of Undef;
   546 
   547 * HOLCF/IMP: updated and converted to new-style theory;
   548 
   549 
   550 *** ZF ***
   551 
   552 * Isar: proper integration of logic-specific tools and packages,
   553 including theory commands '(co)inductive', '(co)datatype',
   554 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   555 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   556 
   557 * theory Main no longer includes AC; for the Axiom of Choice, base
   558 your theory on Main_ZFC;
   559 
   560 * the integer library now covers quotients and remainders, with many
   561 laws relating division to addition, multiplication, etc.;
   562 
   563 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   564 typeless version of the formalism;
   565 
   566 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   567 format;
   568 
   569 * ZF/Induct: new directory for examples of inductive definitions,
   570 including theory Multiset for multiset orderings; converted to
   571 new-style theory format;
   572 
   573 * ZF: many new theorems about lists, ordinals, etc.;
   574 
   575 
   576 *** General ***
   577 
   578 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   579 variable proof controls level of detail: 0 = no proofs (only oracle
   580 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   581 also ref manual for further ML interfaces;
   582 
   583 * Pure/axclass: removed obsolete ML interface
   584 goal_subclass/goal_arity;
   585 
   586 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   587 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   588 separate tokens, so expressions involving minus need to be spaced
   589 properly;
   590 
   591 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   592 rather than "infixl" or "infixr";
   593 
   594 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   595 sort constraint specifications in type inference; e.g. "x::_::foo"
   596 ensures that the type of "x" is of sort "foo" (but not necessarily a
   597 type variable);
   598 
   599 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   600 control output of nested => (types); the default behavior is
   601 "type_brackets";
   602 
   603 * Pure/syntax: builtin parse translation for "_constify" turns valued
   604 tokens into AST constants;
   605 
   606 * Pure/syntax: prefer later declarations of translations and print
   607 translation functions; potential INCOMPATIBILITY: need to reverse
   608 multiple declarations for same syntax element constant;
   609 
   610 * Pure/show_hyps reset by default (in accordance to existing Isar
   611 practice);
   612 
   613 * Provers/classical: renamed addaltern to addafter, addSaltern to
   614 addSafter;
   615 
   616 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   617 as well;
   618 
   619 * system: tested support for MacOS X; should be able to get Isabelle +
   620 Proof General to work in a plain Terminal after installing Poly/ML
   621 (e.g. from the Isabelle distribution area) and GNU bash alone
   622 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   623 support requires further installations, e.g. from
   624 http://fink.sourceforge.net/);
   625 
   626 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   627 
   628 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   629 of 40 MB), cf. ML_OPTIONS;
   630 
   631 * system: Proof General keywords specification is now part of the
   632 Isabelle distribution (see etc/isar-keywords.el);
   633 
   634 * system: support for persistent Proof General sessions (refrain from
   635 outdating all loaded theories on startup); user may create writable
   636 logic images like this: ``isabelle -q HOL Test'';
   637 
   638 * system: smart selection of Isabelle process versus Isabelle
   639 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   640 run both "isabelle" and "Isabelle" even if file names are badly
   641 damaged (executable inspects the case of the first letter of its own
   642 name); added separate "isabelle-process" and "isabelle-interface";
   643 
   644 * system: refrain from any attempt at filtering input streams; no
   645 longer support ``8bit'' encoding of old isabelle font, instead proper
   646 iso-latin characters may now be used; the related isatools
   647 "symbolinput" and "nonascii" have disappeared as well;
   648 
   649 * system: removed old "xterm" interface (the print modes "xterm" and
   650 "xterm_color" are still available for direct use in a suitable
   651 terminal);
   652 
   653 
   654 
   655 New in Isabelle99-2 (February 2001)
   656 -----------------------------------
   657 
   658 *** Overview of INCOMPATIBILITIES ***
   659 
   660 * HOL: please note that theories in the Library and elsewhere often use the
   661 new-style (Isar) format; to refer to their theorems in an ML script you must
   662 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   663 
   664 * HOL: inductive package no longer splits induction rule aggressively,
   665 but only as far as specified by the introductions given; the old
   666 format may be recovered via ML function complete_split_rule or attribute
   667 'split_rule (complete)';
   668 
   669 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   670 gfp_Tarski to gfp_unfold;
   671 
   672 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   673 
   674 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   675 relation); infix "^^" has been renamed "``"; infix "``" has been
   676 renamed "`"; "univalent" has been renamed "single_valued";
   677 
   678 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   679 operation;
   680 
   681 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   682 
   683 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   684 
   685 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   686 consequence, it is no longer monotonic wrt. the local goal context
   687 (which is now passed through the inductive cases);
   688 
   689 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   690 \<gg> to \<ggreater>;
   691 
   692 
   693 *** Document preparation ***
   694 
   695 * \isabellestyle{NAME} selects version of Isabelle output (currently
   696 available: are "it" for near math-mode best-style output, "sl" for
   697 slanted text style, and "tt" for plain type-writer; if no
   698 \isabellestyle command is given, output is according to slanted
   699 type-writer);
   700 
   701 * support sub/super scripts (for single symbols only), input syntax is
   702 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   703 
   704 * some more standard symbols; see Appendix A of the system manual for
   705 the complete list of symbols defined in isabellesym.sty;
   706 
   707 * improved isabelle style files; more abstract symbol implementation
   708 (should now use \isamath{...} and \isatext{...} in custom symbol
   709 definitions);
   710 
   711 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   712 state; Note that presentation of goal states does not conform to
   713 actual human-readable proof documents.  Please do not include goal
   714 states into document output unless you really know what you are doing!
   715 
   716 * proper indentation of antiquoted output with proportional LaTeX
   717 fonts;
   718 
   719 * no_document ML operator temporarily disables LaTeX document
   720 generation;
   721 
   722 * isatool unsymbolize tunes sources for plain ASCII communication;
   723 
   724 
   725 *** Isar ***
   726 
   727 * Pure: Isar now suffers initial goal statements to contain unbound
   728 schematic variables (this does not conform to actual readable proof
   729 documents, due to unpredictable outcome and non-compositional proof
   730 checking); users who know what they are doing may use schematic goals
   731 for Prolog-style synthesis of proven results;
   732 
   733 * Pure: assumption method (an implicit finishing) now handles actual
   734 rules as well;
   735 
   736 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   737 initial goal, declare "that" only as Pure intro (only for single
   738 steps); the "that" rule assumption may now be involved in implicit
   739 finishing, thus ".." becomes a feasible for trivial obtains;
   740 
   741 * Pure: default proof step now includes 'intro_classes'; thus trivial
   742 instance proofs may be performed by "..";
   743 
   744 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   745 statements as well;
   746 
   747 * Pure: more robust selection of calculational rules;
   748 
   749 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   750 rule (as well as the assumption rule);
   751 
   752 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   753 lemmas, using the graph browser tool;
   754 
   755 * Pure: predict failure of "show" in interactive mode;
   756 
   757 * Pure: 'thms_containing' now takes actual terms as arguments;
   758 
   759 * HOL: improved method 'induct' --- now handles non-atomic goals
   760 (potential INCOMPATIBILITY); tuned error handling;
   761 
   762 * HOL: cases and induct rules now provide explicit hints about the
   763 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   764 any remaining facts are inserted into the goal verbatim;
   765 
   766 * HOL: local contexts (aka cases) may now contain term bindings as
   767 well; the 'cases' and 'induct' methods new provide a ?case binding for
   768 the result to be shown in each case;
   769 
   770 * HOL: added 'recdef_tc' command;
   771 
   772 * isatool convert assists in eliminating legacy ML scripts;
   773 
   774 
   775 *** HOL ***
   776 
   777 * HOL/Library: a collection of generic theories to be used together
   778 with main HOL; the theory loader path already includes this directory
   779 by default; the following existing theories have been moved here:
   780 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   781 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   782 
   783 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   784 modelling and verification task performed in Isabelle/HOL +
   785 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   786 
   787 * HOL/Algebra: special summation operator SUM no longer exists, it has
   788 been replaced by setsum; infix 'assoc' now has priority 50 (like
   789 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   790 'domain', this makes the theory consistent with mathematical
   791 literature;
   792 
   793 * HOL basics: added overloaded operations "inverse" and "divide"
   794 (infix "/"), syntax for generic "abs" operation, generic summation
   795 operator \<Sum>;
   796 
   797 * HOL/typedef: simplified package, provide more useful rules (see also
   798 HOL/subset.thy);
   799 
   800 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   801 now expressed as a proper nested rule (old-style tactic scripts may
   802 require atomize_strip_tac to cope with non-atomic premises);
   803 
   804 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   805 to "split_conv" (old name still available for compatibility);
   806 
   807 * HOL: improved concrete syntax for strings (e.g. allows translation
   808 rules with string literals);
   809 
   810 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   811  and Fleuriot's mechanization of analysis, including the transcendental
   812  functions for the reals;
   813 
   814 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   815 
   816 
   817 *** CTT ***
   818 
   819 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   820 "lam" is displayed as TWO lambda-symbols
   821 
   822 * CTT: theory Main now available, containing everything (that is, Bool
   823 and Arith);
   824 
   825 
   826 *** General ***
   827 
   828 * Pure: the Simplifier has been implemented properly as a derived rule
   829 outside of the actual kernel (at last!); the overall performance
   830 penalty in practical applications is about 50%, while reliability of
   831 the Isabelle inference kernel has been greatly improved;
   832 
   833 * print modes "brackets" and "no_brackets" control output of nested =>
   834 (types) and ==> (props); the default behaviour is "brackets";
   835 
   836 * Provers: fast_tac (and friends) now handle actual object-logic rules
   837 as assumptions as well;
   838 
   839 * system: support Poly/ML 4.0;
   840 
   841 * system: isatool install handles KDE version 1 or 2;
   842 
   843 
   844 
   845 New in Isabelle99-1 (October 2000)
   846 ----------------------------------
   847 
   848 *** Overview of INCOMPATIBILITIES ***
   849 
   850 * HOL: simplification of natural numbers is much changed; to partly
   851 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   852 issue the following ML commands:
   853 
   854   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   855   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   856 
   857 * HOL: simplification no longer dives into case-expressions; this is
   858 controlled by "t.weak_case_cong" for each datatype t;
   859 
   860 * HOL: nat_less_induct renamed to less_induct;
   861 
   862 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   863 fixsome to patch .thy and .ML sources automatically;
   864 
   865   select_equality  -> some_equality
   866   select_eq_Ex     -> some_eq_ex
   867   selectI2EX       -> someI2_ex
   868   selectI2         -> someI2
   869   selectI          -> someI
   870   select1_equality -> some1_equality
   871   Eps_sym_eq       -> some_sym_eq_trivial
   872   Eps_eq           -> some_eq_trivial
   873 
   874 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   875 
   876 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   877 instead);
   878 
   879 * HOL: the recursion equations generated by 'recdef' are now called
   880 f.simps instead of f.rules;
   881 
   882 * HOL: qed_spec_mp now also handles bounded ALL as well;
   883 
   884 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   885 sometimes be needed;
   886 
   887 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   888 
   889 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   890 
   891 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   892 product is now "<*>" instead of "Times"; the lexicographic product is
   893 now "<*lex*>" instead of "**";
   894 
   895 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   896 of main HOL, but was unused); better use HOL's datatype package;
   897 
   898 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   899 the old syntax may be recovered as follows:
   900 
   901   syntax (symbols)
   902     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   903       (infixl "\\<oplus>" 100)
   904 
   905 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   906 
   907 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   908 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   909 internally;
   910 
   911 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   912 changed from A/r to A//r;
   913 
   914 * ZF: new treatment of arithmetic (nat & int) may break some old
   915 proofs;
   916 
   917 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   918 rulify -> rule_format, elimify -> elim_format, ...);
   919 
   920 * Isar/Provers: intro/elim/dest attributes changed; renamed
   921 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   922 should have to change intro!! to intro? only); replaced "delrule" by
   923 "rule del";
   924 
   925 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   926 
   927 * Provers: strengthened force_tac by using new first_best_tac;
   928 
   929 * LaTeX document preparation: several changes of isabelle.sty (see
   930 lib/texinputs);
   931 
   932 
   933 *** Document preparation ***
   934 
   935 * formal comments (text blocks etc.) in new-style theories may now
   936 contain antiquotations of thm/prop/term/typ/text to be presented
   937 according to latex print mode; concrete syntax is like this:
   938 @{term[show_types] "f(x) = a + x"};
   939 
   940 * isatool mkdir provides easy setup of Isabelle session directories,
   941 including proper document sources;
   942 
   943 * generated LaTeX sources are now deleted after successful run
   944 (isatool document -c); may retain a copy somewhere else via -D option
   945 of isatool usedir;
   946 
   947 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   948 style files, achieving self-contained LaTeX sources and simplifying
   949 LaTeX debugging;
   950 
   951 * old-style theories now produce (crude) LaTeX output as well;
   952 
   953 * browser info session directories are now self-contained (may be put
   954 on WWW server seperately); improved graphs of nested sessions; removed
   955 graph for 'all sessions';
   956 
   957 * several improvements in isabelle style files; \isabellestyle{it}
   958 produces fake math mode output; \isamarkupheader is now \section by
   959 default; see lib/texinputs/isabelle.sty etc.;
   960 
   961 
   962 *** Isar ***
   963 
   964 * Isar/Pure: local results and corresponding term bindings are now
   965 subject to Hindley-Milner polymorphism (similar to ML); this
   966 accommodates incremental type-inference very nicely;
   967 
   968 * Isar/Pure: new derived language element 'obtain' supports
   969 generalized existence reasoning;
   970 
   971 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   972 support accumulation of results, without applying any rules yet;
   973 useful to collect intermediate results without explicit name
   974 references, and for use with transitivity rules with more than 2
   975 premises;
   976 
   977 * Isar/Pure: scalable support for case-analysis type proofs: new
   978 'case' language element refers to local contexts symbolically, as
   979 produced by certain proof methods; internally, case names are attached
   980 to theorems as "tags";
   981 
   982 * Isar/Pure: theory command 'hide' removes declarations from
   983 class/type/const name spaces;
   984 
   985 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   986 indicate potential overloading;
   987 
   988 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   989 
   990 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   991 "{a,b,c}" instead of {a,b,c};
   992 
   993 * Isar/Pure now provides its own version of intro/elim/dest
   994 attributes; useful for building new logics, but beware of confusion
   995 with the version in Provers/classical;
   996 
   997 * Isar/Pure: the local context of (non-atomic) goals is provided via
   998 case name 'antecedent';
   999 
  1000 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1001 to the current context is now done automatically);
  1002 
  1003 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1004 for definining proof methods in ML;
  1005 
  1006 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1007 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1008 most cases, one should have to change intro!! to intro? only);
  1009 replaced "delrule" by "rule del";
  1010 
  1011 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1012 'symmetric' attribute (the latter supercedes [RS sym]);
  1013 
  1014 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1015 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1016 well (including splits);
  1017 
  1018 * Isar/Provers: Simplifier and Classical methods now support all kind
  1019 of modifiers used in the past, including 'cong', 'iff', etc.
  1020 
  1021 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1022 of Simplifier and Classical reasoner);
  1023 
  1024 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1025 now support named cases; major packages (inductive, datatype, primrec,
  1026 recdef) support case names and properly name parameters;
  1027 
  1028 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1029 monotonicity conditions are extracted to be proven at end of
  1030 calculations;
  1031 
  1032 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1033 method anyway;
  1034 
  1035 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1036 split_if split_if_asm; datatype package provides theorems foo.splits =
  1037 foo.split foo.split_asm for each datatype;
  1038 
  1039 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1040 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1041 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1042 use "(cases (simplified))" method in proper proof texts);
  1043 
  1044 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1045 
  1046 * Isar: names of theorems etc. may be natural numbers as well;
  1047 
  1048 * Isar: 'pr' command: optional arguments for goals_limit and
  1049 ProofContext.prems_limit; no longer prints theory contexts, but only
  1050 proof states;
  1051 
  1052 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1053 additional print modes to be specified; e.g. "pr(latex)" will print
  1054 proof state according to the Isabelle LaTeX style;
  1055 
  1056 * Isar: improved support for emulating tactic scripts, including proof
  1057 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1058 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1059 (for HOL datatypes);
  1060 
  1061 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1062 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1063 'proof method scripts' have to be in depth-first order;
  1064 
  1065 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1066 
  1067 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1068 should instead use individual commands for printing items
  1069 (print_commands, print_methods etc.);
  1070 
  1071 * Isar: added 'nothing' --- the empty list of theorems;
  1072 
  1073 
  1074 *** HOL ***
  1075 
  1076 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1077 corresponding virtual machine and a specification of its bytecode
  1078 verifier and a lightweight bytecode verifier, including proofs of
  1079 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1080 Cornelia Pusch (see also the homepage of project Bali at
  1081 http://isabelle.in.tum.de/Bali/);
  1082 
  1083 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1084 Clemens Ballarin;
  1085 
  1086 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1087 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1088 Rasmussen;
  1089 
  1090 * HOL/Lattice: fundamental concepts of lattice theory and order
  1091 structures, including duals, properties of bounds versus algebraic
  1092 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1093 Theorem for complete lattices etc.; may also serve as a demonstration
  1094 for abstract algebraic reasoning using axiomatic type classes, and
  1095 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1096 
  1097 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1098 von Oheimb;
  1099 
  1100 * HOL/IMPP: extension of IMP with local variables and mutually
  1101 recursive procedures, by David von Oheimb;
  1102 
  1103 * HOL/Lambda: converted into new-style theory and document;
  1104 
  1105 * HOL/ex/Multiquote: example of multiple nested quotations and
  1106 anti-quotations -- basically a generalized version of de-Bruijn
  1107 representation; very useful in avoiding lifting of operations;
  1108 
  1109 * HOL/record: added general record equality rule to simpset; fixed
  1110 select-update simplification procedure to handle extended records as
  1111 well; admit "r" as field name;
  1112 
  1113 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1114 other numeric types and also as the identity of groups, rings, etc.;
  1115 
  1116 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1117 Types nat and int belong to this axclass;
  1118 
  1119 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1120    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1121    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1122   two terms #m*u and #n*u are replaced by #(m+n)*u
  1123     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1124   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1125     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1126 
  1127 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1128 powerful prover for predicate logic but knows nothing of clasets; see
  1129 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1130 
  1131 * HOL: new version of "case_tac" subsumes both boolean case split and
  1132 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1133 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1134 
  1135 * HOL: simplification no longer dives into case-expressions: only the
  1136 selector expression is simplified, but not the remaining arms; to
  1137 enable full simplification of case-expressions for datatype t, you may
  1138 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1139 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1140 
  1141 * HOL/recdef: the recursion equations generated by 'recdef' for
  1142 function 'f' are now called f.simps instead of f.rules; if all
  1143 termination conditions are proved automatically, these simplification
  1144 rules are added to the simpset, as in primrec; rules may be named
  1145 individually as well, resulting in a separate list of theorems for
  1146 each equation;
  1147 
  1148 * HOL/While is a new theory that provides a while-combinator. It
  1149 permits the definition of tail-recursive functions without the
  1150 provision of a termination measure. The latter is necessary once the
  1151 invariant proof rule for while is applied.
  1152 
  1153 * HOL: new (overloaded) notation for the set of elements below/above
  1154 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1155 
  1156 * HOL: theorems impI, allI, ballI bound as "strip";
  1157 
  1158 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1159 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1160 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1161 
  1162 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1163 
  1164 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1165 main HOL, but was unused);
  1166 
  1167 * HOL: fewer consts declared as global (e.g. have to refer to
  1168 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1169 
  1170 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1171 in case of overlap with user translations (e.g. judgements over
  1172 tuples); (note that the underlying logical represenation is still
  1173 bogus);
  1174 
  1175 
  1176 *** ZF ***
  1177 
  1178 * ZF: simplification automatically cancels common terms in arithmetic
  1179 expressions over nat and int;
  1180 
  1181 * ZF: new treatment of nat to minimize type-checking: all operators
  1182 coerce their operands to a natural number using the function natify,
  1183 making the algebraic laws unconditional;
  1184 
  1185 * ZF: as above, for int: operators coerce their operands to an integer
  1186 using the function intify;
  1187 
  1188 * ZF: the integer library now contains many of the usual laws for the
  1189 orderings, including $<=, and monotonicity laws for $+ and $*;
  1190 
  1191 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1192 simplification;
  1193 
  1194 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1195 to the simplifier and classical reasoner simultaneously;
  1196 
  1197 
  1198 *** General ***
  1199 
  1200 * Provers: blast_tac now handles actual object-logic rules as
  1201 assumptions; note that auto_tac uses blast_tac internally as well;
  1202 
  1203 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1204 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1205 
  1206 * Provers: delrules now handles destruct rules as well (no longer need
  1207 explicit make_elim);
  1208 
  1209 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1210   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1211 use instead the strong form,
  1212   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1213 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1214 from destruct-rules;
  1215 
  1216 * Provers: Simplifier.easy_setup provides a fast path to basic
  1217 Simplifier setup for new object-logics;
  1218 
  1219 * Pure: AST translation rules no longer require constant head on LHS;
  1220 
  1221 * Pure: improved name spaces: ambiguous output is qualified; support
  1222 for hiding of names;
  1223 
  1224 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1225 XSYMBOL_HOME; no longer need to do manual configuration in most
  1226 situations;
  1227 
  1228 * system: compression of ML heaps images may now be controlled via -c
  1229 option of isabelle and isatool usedir (currently only observed by
  1230 Poly/ML);
  1231 
  1232 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1233 useful for remote X11);
  1234 
  1235 * system: provide TAGS file for Isabelle sources;
  1236 
  1237 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1238 order;
  1239 
  1240 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1241 timing flag supersedes proof_timing and Toplevel.trace;
  1242 
  1243 * ML: new combinators |>> and |>>> for incremental transformations
  1244 with secondary results (e.g. certain theory extensions):
  1245 
  1246 * ML: PureThy.add_defs gets additional argument to indicate potential
  1247 overloading (usually false);
  1248 
  1249 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1250 results;
  1251 
  1252 
  1253 
  1254 New in Isabelle99 (October 1999)
  1255 --------------------------------
  1256 
  1257 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1258 
  1259 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1260 are no longer simplified.  (This allows the simplifier to unfold recursive
  1261 functional programs.)  To restore the old behaviour, declare
  1262 
  1263     Delcongs [if_weak_cong];
  1264 
  1265 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1266 complement;
  1267 
  1268 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1269 
  1270 * HOL/datatype: mutual_induct_tac no longer exists --
  1271   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1272 
  1273 * HOL/typedef: fixed type inference for representing set; type
  1274 arguments now have to occur explicitly on the rhs as type constraints;
  1275 
  1276 * ZF: The con_defs part of an inductive definition may no longer refer
  1277 to constants declared in the same theory;
  1278 
  1279 * HOL, ZF: the function mk_cases, generated by the inductive
  1280 definition package, has lost an argument.  To simplify its result, it
  1281 uses the default simpset instead of a supplied list of theorems.
  1282 
  1283 * HOL/List: the constructors of type list are now Nil and Cons;
  1284 
  1285 * Simplifier: the type of the infix ML functions
  1286         setSSolver addSSolver setSolver addSolver
  1287 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1288 for packaging solvers. A solver is created via
  1289         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1290 where the string argument is only a comment.
  1291 
  1292 
  1293 *** Proof tools ***
  1294 
  1295 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1296 decision procedure for linear arithmetic. Currently it is used for
  1297 types `nat', `int', and `real' in HOL (see below); it can, should and
  1298 will be instantiated for other types and logics as well.
  1299 
  1300 * The simplifier now accepts rewrite rules with flexible heads, eg
  1301      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1302   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1303   matching.
  1304 
  1305 
  1306 *** General ***
  1307 
  1308 * New Isabelle/Isar subsystem provides an alternative to traditional
  1309 tactical theorem proving; together with the ProofGeneral/isar user
  1310 interface it offers an interactive environment for developing human
  1311 readable proof documents (Isar == Intelligible semi-automated
  1312 reasoning); for further information see isatool doc isar-ref,
  1313 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1314 
  1315 * improved and simplified presentation of theories: better HTML markup
  1316 (including colors), graph views in several sizes; isatool usedir now
  1317 provides a proper interface for user theories (via -P option); actual
  1318 document preparation based on (PDF)LaTeX is available as well (for
  1319 new-style theories only); see isatool doc system for more information;
  1320 
  1321 * native support for Proof General, both for classic Isabelle and
  1322 Isabelle/Isar;
  1323 
  1324 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1325 using the graph browser tool;
  1326 
  1327 * Isabelle manuals now also available as PDF;
  1328 
  1329 * theory loader rewritten from scratch (may not be fully
  1330 bug-compatible); old loadpath variable has been replaced by show_path,
  1331 add_path, del_path, reset_path functions; new operations such as
  1332 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1333 isatool doc ref);
  1334 
  1335 * improved isatool install: option -k creates KDE application icon,
  1336 option -p DIR installs standalone binaries;
  1337 
  1338 * added ML_PLATFORM setting (useful for cross-platform installations);
  1339 more robust handling of platform specific ML images for SML/NJ;
  1340 
  1341 * the settings environment is now statically scoped, i.e. it is never
  1342 created again in sub-processes invoked from isabelle, isatool, or
  1343 Isabelle;
  1344 
  1345 * path element specification '~~' refers to '$ISABELLE_HOME';
  1346 
  1347 * in locales, the "assumes" and "defines" parts may be omitted if
  1348 empty;
  1349 
  1350 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1351 long arrows);
  1352 
  1353 * new print_mode "HTML";
  1354 
  1355 * new flag show_tags controls display of tags of theorems (which are
  1356 basically just comments that may be attached by some tools);
  1357 
  1358 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1359 mode and goal output format:
  1360 
  1361 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1362 244c244
  1363 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1364 ---
  1365 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1366 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1367 181c181
  1368 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1369 ---
  1370 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1371 
  1372 * function bind_thms stores lists of theorems (cf. bind_thm);
  1373 
  1374 * new shorthand tactics ftac, eatac, datac, fatac;
  1375 
  1376 * qed (and friends) now accept "" as result name; in that case the
  1377 theorem is not stored, but proper checks and presentation of the
  1378 result still apply;
  1379 
  1380 * theorem database now also indexes constants "Trueprop", "all",
  1381 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1382 
  1383 
  1384 *** HOL ***
  1385 
  1386 ** HOL arithmetic **
  1387 
  1388 * There are now decision procedures for linear arithmetic over nat and
  1389 int:
  1390 
  1391 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1392 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1393 are treated as atomic; subformulae not involving type `nat' or `int'
  1394 are ignored; quantified subformulae are ignored unless they are
  1395 positive universal or negative existential. The tactic has to be
  1396 invoked by hand and can be a little bit slow. In particular, the
  1397 running time is exponential in the number of occurrences of `min' and
  1398 `max', and `-' on `nat'.
  1399 
  1400 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1401 (negated) (in)equalities among the premises and the conclusion into
  1402 account (i.e. no compound formulae) and does not know about `min' and
  1403 `max', and `-' on `nat'. It is fast and is used automatically by the
  1404 simplifier.
  1405 
  1406 NB: At the moment, these decision procedures do not cope with mixed
  1407 nat/int formulae where the two parts interact, such as `m < n ==>
  1408 int(m) < int(n)'.
  1409 
  1410 * HOL/Numeral provides a generic theory of numerals (encoded
  1411 efficiently as bit strings); setup for types nat/int/real is in place;
  1412 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1413 int, existing theories and proof scripts may require a few additional
  1414 type constraints;
  1415 
  1416 * integer division and remainder can now be performed on constant
  1417 arguments;
  1418 
  1419 * many properties of integer multiplication, division and remainder
  1420 are now available;
  1421 
  1422 * An interface to the Stanford Validity Checker (SVC) is available through the
  1423 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1424 are proved automatically.  SVC must be installed separately, and its results
  1425 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1426 invocation of the underlying oracle).  For SVC see
  1427   http://verify.stanford.edu/SVC
  1428 
  1429 * IsaMakefile: the HOL-Real target now builds an actual image;
  1430 
  1431 
  1432 ** HOL misc **
  1433 
  1434 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1435 (in Isabelle/Isar) -- by Gertrud Bauer;
  1436 
  1437 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1438 analysis for assembly languages with subtypes;
  1439 
  1440 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1441 -- avoids syntactic ambiguities and treats state, transition, and
  1442 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1443 changed syntax and (many) tactics;
  1444 
  1445 * HOL/inductive: Now also handles more general introduction rules such
  1446   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1447   theorems are now maintained within the theory (maintained via the
  1448   "mono" attribute);
  1449 
  1450 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1451   (using function types) such as
  1452 
  1453   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1454 
  1455 * HOL/record: record_simproc (part of the default simpset) takes care
  1456 of selectors applied to updated records; record_split_tac is no longer
  1457 part of the default claset; update_defs may now be removed from the
  1458 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1459 
  1460   claset_ref () := claset() addSWrapper record_split_wrapper;
  1461   Delsimprocs [record_simproc]
  1462 
  1463 * HOL/typedef: fixed type inference for representing set; type
  1464 arguments now have to occur explicitly on the rhs as type constraints;
  1465 
  1466 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1467 names rather than an ML expression;
  1468 
  1469 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1470 supplied later.  Program schemes can be defined, such as
  1471     "While B C s = (if B s then While B C (C s) else s)"
  1472 where the well-founded relation can be chosen after B and C have been given.
  1473 
  1474 * HOL/List: the constructors of type list are now Nil and Cons;
  1475 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1476 course, ML tools referring to List.list.op # etc. have to be adapted;
  1477 
  1478 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1479 disabled by default; run isabelle with option -m HOL to get back to
  1480 the original Gordon/HOL-style output;
  1481 
  1482 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1483 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1484 
  1485 * HOL basic syntax simplified (more orthogonal): all variants of
  1486 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1487 Eps operator is provided as well: "SOME x. P[x]";
  1488 
  1489 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1490 
  1491 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1492 thus available for user theories;
  1493 
  1494 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1495 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1496 time;
  1497 
  1498 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1499 several times and then mp;
  1500 
  1501 
  1502 *** LK ***
  1503 
  1504 * the notation <<...>> is now available as a notation for sequences of
  1505 formulas;
  1506 
  1507 * the simplifier is now installed
  1508 
  1509 * the axiom system has been generalized (thanks to Soren Heilmann)
  1510 
  1511 * the classical reasoner now has a default rule database
  1512 
  1513 
  1514 *** ZF ***
  1515 
  1516 * new primrec section allows primitive recursive functions to be given
  1517 directly (as in HOL) over datatypes and the natural numbers;
  1518 
  1519 * new tactics induct_tac and exhaust_tac for induction (or case
  1520 analysis) over datatypes and the natural numbers;
  1521 
  1522 * the datatype declaration of type T now defines the recursor T_rec;
  1523 
  1524 * simplification automatically does freeness reasoning for datatype
  1525 constructors;
  1526 
  1527 * automatic type-inference, with AddTCs command to insert new
  1528 type-checking rules;
  1529 
  1530 * datatype introduction rules are now added as Safe Introduction rules
  1531 to the claset;
  1532 
  1533 * the syntax "if P then x else y" is now available in addition to
  1534 if(P,x,y);
  1535 
  1536 
  1537 *** Internal programming interfaces ***
  1538 
  1539 * tuned simplifier trace output; new flag debug_simp;
  1540 
  1541 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1542 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1543 
  1544 * AxClass.axclass_tac lost the theory argument;
  1545 
  1546 * tuned current_goals_markers semantics: begin / end goal avoids
  1547 printing empty lines;
  1548 
  1549 * removed prs and prs_fn hook, which was broken because it did not
  1550 include \n in its semantics, forcing writeln to add one
  1551 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1552 string -> unit if you really want to output text without newline;
  1553 
  1554 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1555 plain output, interface builders may have to enable 'isabelle_font'
  1556 mode to get Isabelle font glyphs as before;
  1557 
  1558 * refined token_translation interface; INCOMPATIBILITY: output length
  1559 now of type real instead of int;
  1560 
  1561 * theory loader actions may be traced via new ThyInfo.add_hook
  1562 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1563 your own database of information attached to *whole* theories -- as
  1564 opposed to intra-theory data slots offered via TheoryDataFun;
  1565 
  1566 * proper handling of dangling sort hypotheses (at last!);
  1567 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1568 extra sort hypotheses that can be witnessed from the type signature;
  1569 the force_strip_shyps flag is gone, any remaining shyps are simply
  1570 left in the theorem (with a warning issued by strip_shyps_warning);
  1571 
  1572 
  1573 
  1574 New in Isabelle98-1 (October 1998)
  1575 ----------------------------------
  1576 
  1577 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1578 
  1579 * several changes of automated proof tools;
  1580 
  1581 * HOL: major changes to the inductive and datatype packages, including
  1582 some minor incompatibilities of theory syntax;
  1583 
  1584 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1585 called `inj_on';
  1586 
  1587 * HOL: removed duplicate thms in Arith:
  1588   less_imp_add_less  should be replaced by  trans_less_add1
  1589   le_imp_add_le      should be replaced by  trans_le_add1
  1590 
  1591 * HOL: unary minus is now overloaded (new type constraints may be
  1592 required);
  1593 
  1594 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1595 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1596 now taken as an integer constant.
  1597 
  1598 * Pure: ML function 'theory_of' renamed to 'theory';
  1599 
  1600 
  1601 *** Proof tools ***
  1602 
  1603 * Simplifier:
  1604   1. Asm_full_simp_tac is now more aggressive.
  1605      1. It will sometimes reorient premises if that increases their power to
  1606         simplify.
  1607      2. It does no longer proceed strictly from left to right but may also
  1608         rotate premises to achieve further simplification.
  1609      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1610      old Asm_full_simp_tac in that it does not rotate premises.
  1611   2. The simplifier now knows a little bit about nat-arithmetic.
  1612 
  1613 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1614 allows for selected deletion of wrappers, by introduction of names for
  1615 wrapper functionals.  This implies that addbefore, addSbefore,
  1616 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1617 and that adding two tactics with the same name overwrites the first
  1618 one (emitting a warning).
  1619   type wrapper = (int -> tactic) -> (int -> tactic)
  1620   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1621   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1622   delWrapper, delSWrapper: claset *  string            -> claset
  1623   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1624 
  1625 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1626 semantics; addbefore now affects only the unsafe part of step_tac
  1627 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1628 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1629 by Force_tac;
  1630 
  1631 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1632 compWrapper; added safe wrapper (and access functions for it);
  1633 
  1634 * HOL/split_all_tac is now much faster and fails if there is nothing
  1635 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1636 and the names of the automatically generated variables have changed.
  1637 split_all_tac has moved within claset() from unsafe wrappers to safe
  1638 wrappers, which means that !!-bound variables are split much more
  1639 aggressively, and safe_tac and clarify_tac now split such variables.
  1640 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1641 Note: the same holds for record_split_tac, which does the job of
  1642 split_all_tac for record fields.
  1643 
  1644 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1645 permanently to the default simpset using Addsplits just like
  1646 Addsimps. They can be removed via Delsplits just like
  1647 Delsimps. Lower-case versions are also available.
  1648 
  1649 * HOL/Simplifier: The rule split_if is now part of the default
  1650 simpset. This means that the simplifier will eliminate all occurrences
  1651 of if-then-else in the conclusion of a goal. To prevent this, you can
  1652 either remove split_if completely from the default simpset by
  1653 `Delsplits [split_if]' or remove it in a specific call of the
  1654 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1655 other case splitting rules to/from the default simpset: every datatype
  1656 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1657 t is the name of the datatype).
  1658 
  1659 * Classical reasoner / Simplifier combination: new force_tac (and
  1660 derivatives Force_tac, force) combines rewriting and classical
  1661 reasoning (and whatever other tools) similarly to auto_tac, but is
  1662 aimed to solve the given subgoal completely.
  1663 
  1664 
  1665 *** General ***
  1666 
  1667 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1668 and `goalw': the theory is no longer needed as an explicit argument -
  1669 the current theory context is used; assumptions are no longer returned
  1670 at the ML-level unless one of them starts with ==> or !!; it is
  1671 recommended to convert to these new commands using isatool fixgoal
  1672 (backup your sources first!);
  1673 
  1674 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1675 the current theory context, and 'theory' to lookup stored theories;
  1676 
  1677 * new theory section 'locale' for declaring constants, assumptions and
  1678 definitions that have local scope;
  1679 
  1680 * new theory section 'nonterminals' for purely syntactic types;
  1681 
  1682 * new theory section 'setup' for generic ML setup functions
  1683 (e.g. package initialization);
  1684 
  1685 * the distribution now includes Isabelle icons: see
  1686 lib/logo/isabelle-{small,tiny}.xpm;
  1687 
  1688 * isatool install - install binaries with absolute references to
  1689 ISABELLE_HOME/bin;
  1690 
  1691 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1692 
  1693 * print mode 'emacs' reserved for Isamode;
  1694 
  1695 * support multiple print (ast) translations per constant name;
  1696 
  1697 * theorems involving oracles are now printed with a suffixed [!];
  1698 
  1699 
  1700 *** HOL ***
  1701 
  1702 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1703 
  1704 * HOL/inductive package reorganized and improved: now supports mutual
  1705 definitions such as
  1706 
  1707   inductive EVEN ODD
  1708     intrs
  1709       null "0 : EVEN"
  1710       oddI "n : EVEN ==> Suc n : ODD"
  1711       evenI "n : ODD ==> Suc n : EVEN"
  1712 
  1713 new theorem list "elims" contains an elimination rule for each of the
  1714 recursive sets; inductive definitions now handle disjunctive premises
  1715 correctly (also ZF);
  1716 
  1717 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1718 "mutual_induct" no longer exists - the induction rule is always
  1719 contained in "induct";
  1720 
  1721 
  1722 * HOL/datatype package re-implemented and greatly improved: now
  1723 supports mutually recursive datatypes such as
  1724 
  1725   datatype
  1726     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1727             | SUM ('a aexp) ('a aexp)
  1728             | DIFF ('a aexp) ('a aexp)
  1729             | NUM 'a
  1730   and
  1731     'a bexp = LESS ('a aexp) ('a aexp)
  1732             | AND ('a bexp) ('a bexp)
  1733             | OR ('a bexp) ('a bexp)
  1734 
  1735 as well as indirectly recursive datatypes such as
  1736 
  1737   datatype
  1738     ('a, 'b) term = Var 'a
  1739                   | App 'b ((('a, 'b) term) list)
  1740 
  1741 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1742 induction on mutually / indirectly recursive datatypes.
  1743 
  1744 Primrec equations are now stored in theory and can be accessed via
  1745 <function_name>.simps.
  1746 
  1747 INCOMPATIBILITIES:
  1748 
  1749   - Theories using datatypes must now have theory Datatype as an
  1750     ancestor.
  1751   - The specific <typename>.induct_tac no longer exists - use the
  1752     generic induct_tac instead.
  1753   - natE has been renamed to nat.exhaust - use exhaust_tac
  1754     instead of res_inst_tac ... natE. Note that the variable
  1755     names in nat.exhaust differ from the names in natE, this
  1756     may cause some "fragile" proofs to fail.
  1757   - The theorems split_<typename>_case and split_<typename>_case_asm
  1758     have been renamed to <typename>.split and <typename>.split_asm.
  1759   - Since default sorts of type variables are now handled correctly,
  1760     some datatype definitions may have to be annotated with explicit
  1761     sort constraints.
  1762   - Primrec definitions no longer require function name and type
  1763     of recursive argument.
  1764 
  1765 Consider using isatool fixdatatype to adapt your theories and proof
  1766 scripts to the new package (backup your sources first!).
  1767 
  1768 
  1769 * HOL/record package: considerably improved implementation; now
  1770 includes concrete syntax for record types, terms, updates; theorems
  1771 for surjective pairing and splitting !!-bound record variables; proof
  1772 support is as follows:
  1773 
  1774   1) standard conversions (selectors or updates applied to record
  1775 constructor terms) are part of the standard simpset;
  1776 
  1777   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1778 made part of standard simpset and claset via addIffs;
  1779 
  1780   3) a tactic for record field splitting (record_split_tac) is part of
  1781 the standard claset (addSWrapper);
  1782 
  1783 To get a better idea about these rules you may retrieve them via
  1784 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1785 the name of your record type.
  1786 
  1787 The split tactic 3) conceptually simplifies by the following rule:
  1788 
  1789   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1790 
  1791 Thus any record variable that is bound by meta-all will automatically
  1792 blow up into some record constructor term, consequently the
  1793 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1794 solve record problems automatically.
  1795 
  1796 
  1797 * reorganized the main HOL image: HOL/Integ and String loaded by
  1798 default; theory Main includes everything;
  1799 
  1800 * automatic simplification of integer sums and comparisons, using cancellation;
  1801 
  1802 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1803 
  1804 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1805 
  1806 * many new identities for unions, intersections, set difference, etc.;
  1807 
  1808 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1809 called split_if, split_split, split_sum_case and split_nat_case (to go
  1810 with add/delsplits);
  1811 
  1812 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1813 (?x::unit) = (); this is made part of the default simpset, which COULD
  1814 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1815 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1816 unit_abs_eta_conv is added in order to counter the effect of
  1817 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1818 %u.f();
  1819 
  1820 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1821 makes more sense);
  1822 
  1823 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1824   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1825   disjointness reasoning but breaking a few old proofs.
  1826 
  1827 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1828 to 'converse' from 'inverse' (for compatibility with ZF and some
  1829 literature);
  1830 
  1831 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1832 the well-founded relation;
  1833 
  1834 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1835     Compl A.  The "Compl" syntax remains available as input syntax for this
  1836     release ONLY.
  1837 
  1838 * HOL/Update: new theory of function updates:
  1839     f(a:=b) == %x. if x=a then b else f x
  1840 may also be iterated as in f(a:=b,c:=d,...);
  1841 
  1842 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1843 
  1844 * HOL/List:
  1845   - new function list_update written xs[i:=v] that updates the i-th
  1846     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1847   - new function `upt' written [i..j(] which generates the list
  1848     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1849     bound write [i..j], which is a shorthand for [i..j+1(].
  1850   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1851 
  1852 * HOL/Arith:
  1853   - removed 'pred' (predecessor) function;
  1854   - generalized some theorems about n-1;
  1855   - many new laws about "div" and "mod";
  1856   - new laws about greatest common divisors (see theory ex/Primes);
  1857 
  1858 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1859 instead of "inverse";
  1860 
  1861 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1862   of the multiset ordering;
  1863 
  1864 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1865   (not included by default);
  1866 
  1867 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1868 
  1869 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1870   programs, i.e. different program variables may have different types.
  1871 
  1872 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1873   [previously, this check worked only if the rewrite rule was unconditional]
  1874   Now rew can involve either definitions or equalities (either == or =).
  1875 
  1876 
  1877 *** ZF ***
  1878 
  1879 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1880   only the theorems proved on ZF.ML;
  1881 
  1882 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1883   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1884   disjointness reasoning but breaking a few old proofs.
  1885 
  1886 * ZF/Update: new theory of function updates
  1887     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1888   may also be iterated as in f(a:=b,c:=d,...);
  1889 
  1890 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1891 
  1892 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1893   [previously, this check worked only if the rewrite rule was unconditional]
  1894   Now rew can involve either definitions or equalities (either == or =).
  1895 
  1896 * case_tac provided for compatibility with HOL
  1897     (like the old excluded_middle_tac, but with subgoals swapped)
  1898 
  1899 
  1900 *** Internal programming interfaces ***
  1901 
  1902 * Pure: several new basic modules made available for general use, see
  1903 also src/Pure/README;
  1904 
  1905 * improved the theory data mechanism to support encapsulation (data
  1906 kind name replaced by private Object.kind, acting as authorization
  1907 key); new type-safe user interface via functor TheoryDataFun; generic
  1908 print_data function becomes basically useless;
  1909 
  1910 * removed global_names compatibility flag -- all theory declarations
  1911 are qualified by default;
  1912 
  1913 * module Pure/Syntax now offers quote / antiquote translation
  1914 functions (useful for Hoare logic etc. with implicit dependencies);
  1915 see HOL/ex/Antiquote for an example use;
  1916 
  1917 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1918 cterm -> thm;
  1919 
  1920 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1921 subgoal;
  1922 
  1923 * Display.print_goals function moved to Locale.print_goals;
  1924 
  1925 * standard print function for goals supports current_goals_markers
  1926 variable for marking begin of proof, end of proof, start of goal; the
  1927 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1928 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1929 for example;
  1930 
  1931 
  1932 
  1933 New in Isabelle98 (January 1998)
  1934 --------------------------------
  1935 
  1936 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1937 
  1938 * changed lexical syntax of terms / types: dots made part of long
  1939 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1940 
  1941 * simpset (and claset) reference variable replaced by functions
  1942 simpset / simpset_ref;
  1943 
  1944 * no longer supports theory aliases (via merge) and non-trivial
  1945 implicit merge of thms' signatures;
  1946 
  1947 * most internal names of constants changed due to qualified names;
  1948 
  1949 * changed Pure/Sequence interface (see Pure/seq.ML);
  1950 
  1951 
  1952 *** General Changes ***
  1953 
  1954 * hierachically structured name spaces (for consts, types, axms, thms
  1955 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1956 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1957 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1958 long_names for fully qualified output names; NOTE: ML programs
  1959 (special tactics, packages etc.) referring to internal names may have
  1960 to be adapted to cope with fully qualified names; in case of severe
  1961 backward campatibility problems try setting 'global_names' at compile
  1962 time to have enrything declared within a flat name space; one may also
  1963 fine tune name declarations in theories via the 'global' and 'local'
  1964 section;
  1965 
  1966 * reimplemented the implicit simpset and claset using the new anytype
  1967 data filed in signatures; references simpset:simpset ref etc. are
  1968 replaced by functions simpset:unit->simpset and
  1969 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1970 to patch your ML files accordingly;
  1971 
  1972 * HTML output now includes theory graph data for display with Java
  1973 applet or isatool browser; data generated automatically via isatool
  1974 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1975 
  1976 * defs may now be conditional; improved rewrite_goals_tac to handle
  1977 conditional equations;
  1978 
  1979 * defs now admits additional type arguments, using TYPE('a) syntax;
  1980 
  1981 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1982 creates a new theory node; implicit merge of thms' signatures is
  1983 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1984 transfer:theory->thm->thm in (rare) cases;
  1985 
  1986 * improved handling of draft signatures / theories; draft thms (and
  1987 ctyps, cterms) are automatically promoted to real ones;
  1988 
  1989 * slightly changed interfaces for oracles: admit many per theory, named
  1990 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1991 
  1992 * print_goals: optional output of const types (set show_consts and
  1993 show_types);
  1994 
  1995 * improved output of warnings (###) and errors (***);
  1996 
  1997 * subgoal_tac displays a warning if the new subgoal has type variables;
  1998 
  1999 * removed old README and Makefiles;
  2000 
  2001 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2002 
  2003 * removed obsolete init_pps and init_database;
  2004 
  2005 * deleted the obsolete tactical STATE, which was declared by
  2006     fun STATE tacfun st = tacfun st st;
  2007 
  2008 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2009 (which abbreviates $HOME);
  2010 
  2011 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2012 use isatool fixseq to adapt your ML programs (this works for fully
  2013 qualified references to the Sequence structure only!);
  2014 
  2015 * use_thy no longer requires writable current directory; it always
  2016 reloads .ML *and* .thy file, if either one is out of date;
  2017 
  2018 
  2019 *** Classical Reasoner ***
  2020 
  2021 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2022 tactics that use classical reasoning to simplify a subgoal without
  2023 splitting it into several subgoals;
  2024 
  2025 * Safe_tac: like safe_tac but uses the default claset;
  2026 
  2027 
  2028 *** Simplifier ***
  2029 
  2030 * added simplification meta rules:
  2031     (asm_)(full_)simplify: simpset -> thm -> thm;
  2032 
  2033 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2034 logics (again);
  2035 
  2036 * added prems argument to simplification procedures;
  2037 
  2038 * HOL, FOL, ZF: added infix function `addsplits':
  2039   instead of `<simpset> setloop (split_tac <thms>)'
  2040   you can simply write `<simpset> addsplits <thms>'
  2041 
  2042 
  2043 *** Syntax ***
  2044 
  2045 * TYPE('a) syntax for type reflection terms;
  2046 
  2047 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2048 
  2049 * pretty printer: changed order of mixfix annotation preference (again!);
  2050 
  2051 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2052 
  2053 
  2054 *** HOL ***
  2055 
  2056 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2057   with `addloop' of the simplifier to faciliate case splitting in premises.
  2058 
  2059 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2060 
  2061 * HOL/Auth: new protocol proofs including some for the Internet
  2062   protocol TLS;
  2063 
  2064 * HOL/Map: new theory of `maps' a la VDM;
  2065 
  2066 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2067 cancelling out common nat summands from =, <, <= (in)equalities, or
  2068 differences; simplification procedures nat_cancel_factor for
  2069 cancelling common factor from =, <, <= (in)equalities over natural
  2070 sums; nat_cancel contains both kinds of procedures, it is installed by
  2071 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2072 
  2073 * HOL/simplifier: terms of the form
  2074   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2075   are rewritten to
  2076   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2077   and those of the form
  2078   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2079   are rewritten to
  2080   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2081 
  2082 * HOL/datatype
  2083   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2084 
  2085   P(t_case f1 ... fn x) =
  2086      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2087         ...
  2088        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2089      )
  2090 
  2091   and a theorem `split_t_case_asm' of the form
  2092 
  2093   P(t_case f1 ... fn x) =
  2094     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2095         ...
  2096        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2097      )
  2098   which can be added to a simpset via `addsplits'. The existing theorems
  2099   expand_list_case and expand_option_case have been renamed to
  2100   split_list_case and split_option_case.
  2101 
  2102 * HOL/Arithmetic:
  2103   - `pred n' is automatically converted to `n-1'.
  2104     Users are strongly encouraged not to use `pred' any longer,
  2105     because it will disappear altogether at some point.
  2106   - Users are strongly encouraged to write "0 < n" rather than
  2107     "n ~= 0". Theorems and proof tools have been modified towards this
  2108     `standard'.
  2109 
  2110 * HOL/Lists:
  2111   the function "set_of_list" has been renamed "set" (and its theorems too);
  2112   the function "nth" now takes its arguments in the reverse order and
  2113   has acquired the infix notation "!" as in "xs!n".
  2114 
  2115 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2116 
  2117 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2118   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2119 
  2120 * HOL/record: extensible records with schematic structural subtyping
  2121 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2122 still lacks various theorems and concrete record syntax;
  2123 
  2124 
  2125 *** HOLCF ***
  2126 
  2127 * removed "axioms" and "generated by" sections;
  2128 
  2129 * replaced "ops" section by extended "consts" section, which is capable of
  2130   handling the continuous function space "->" directly;
  2131 
  2132 * domain package:
  2133   . proves theorems immediately and stores them in the theory,
  2134   . creates hierachical name space,
  2135   . now uses normal mixfix annotations (instead of cinfix...),
  2136   . minor changes to some names and values (for consistency),
  2137   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2138   . separator between mutual domain defs: changed "," to "and",
  2139   . improved handling of sort constraints;  now they have to
  2140     appear on the left-hand side of the equations only;
  2141 
  2142 * fixed LAM <x,y,zs>.b syntax;
  2143 
  2144 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2145 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2146 
  2147 
  2148 *** FOL and ZF ***
  2149 
  2150 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2151   with `addloop' of the simplifier to faciliate case splitting in premises.
  2152 
  2153 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2154 in HOL, they strip ALL and --> from proved theorems;
  2155 
  2156 
  2157 
  2158 New in Isabelle94-8 (May 1997)
  2159 ------------------------------
  2160 
  2161 *** General Changes ***
  2162 
  2163 * new utilities to build / run / maintain Isabelle etc. (in parts
  2164 still somewhat experimental); old Makefiles etc. still functional;
  2165 
  2166 * new 'Isabelle System Manual';
  2167 
  2168 * INSTALL text, together with ./configure and ./build scripts;
  2169 
  2170 * reimplemented type inference for greater efficiency, better error
  2171 messages and clean internal interface;
  2172 
  2173 * prlim command for dealing with lots of subgoals (an easier way of
  2174 setting goals_limit);
  2175 
  2176 
  2177 *** Syntax ***
  2178 
  2179 * supports alternative (named) syntax tables (parser and pretty
  2180 printer); internal interface is provided by add_modesyntax(_i);
  2181 
  2182 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2183 be used in conjunction with the Isabelle symbol font; uses the
  2184 "symbols" syntax table;
  2185 
  2186 * added token_translation interface (may translate name tokens in
  2187 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2188 the current print_mode); IMPORTANT: user print translation functions
  2189 are responsible for marking newly introduced bounds
  2190 (Syntax.mark_boundT);
  2191 
  2192 * token translations for modes "xterm" and "xterm_color" that display
  2193 names in bold, underline etc. or colors (which requires a color
  2194 version of xterm);
  2195 
  2196 * infixes may now be declared with names independent of their syntax;
  2197 
  2198 * added typed_print_translation (like print_translation, but may
  2199 access type of constant);
  2200 
  2201 
  2202 *** Classical Reasoner ***
  2203 
  2204 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2205 some limitations.  Blast_tac...
  2206   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2207   + ignores elimination rules that don't have the correct format
  2208         (the conclusion MUST be a formula variable)
  2209   + ignores types, which can make HOL proofs fail
  2210   + rules must not require higher-order unification, e.g. apply_type in ZF
  2211     [message "Function Var's argument not a bound variable" relates to this]
  2212   + its proof strategy is more general but can actually be slower
  2213 
  2214 * substitution with equality assumptions no longer permutes other
  2215 assumptions;
  2216 
  2217 * minor changes in semantics of addafter (now called addaltern); renamed
  2218 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2219 (and access functions for it);
  2220 
  2221 * improved combination of classical reasoner and simplifier:
  2222   + functions for handling clasimpsets
  2223   + improvement of addss: now the simplifier is called _after_ the
  2224     safe steps.
  2225   + safe variant of addss called addSss: uses safe simplifications
  2226     _during_ the safe steps. It is more complete as it allows multiple
  2227     instantiations of unknowns (e.g. with slow_tac).
  2228 
  2229 *** Simplifier ***
  2230 
  2231 * added interface for simplification procedures (functions that
  2232 produce *proven* rewrite rules on the fly, depending on current
  2233 redex);
  2234 
  2235 * ordering on terms as parameter (used for ordered rewriting);
  2236 
  2237 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2238 
  2239 * the solver is now split into a safe and an unsafe part.
  2240 This should be invisible for the normal user, except that the
  2241 functions setsolver and addsolver have been renamed to setSolver and
  2242 addSolver; added safe_asm_full_simp_tac;
  2243 
  2244 
  2245 *** HOL ***
  2246 
  2247 * a generic induction tactic `induct_tac' which works for all datatypes and
  2248 also for type `nat';
  2249 
  2250 * a generic case distinction tactic `exhaust_tac' which works for all
  2251 datatypes and also for type `nat';
  2252 
  2253 * each datatype comes with a function `size';
  2254 
  2255 * patterns in case expressions allow tuple patterns as arguments to
  2256 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2257 
  2258 * primrec now also works with type nat;
  2259 
  2260 * recdef: a new declaration form, allows general recursive functions to be
  2261 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2262 
  2263 * the constant for negation has been renamed from "not" to "Not" to
  2264 harmonize with FOL, ZF, LK, etc.;
  2265 
  2266 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2267 infinite lists;
  2268 
  2269 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2270 
  2271 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2272 problems in commutative rings, using axiomatic type classes for + and *;
  2273 
  2274 * more examples in HOL/MiniML and HOL/Auth;
  2275 
  2276 * more default rewrite rules for quantifiers, union/intersection;
  2277 
  2278 * a new constant `arbitrary == @x.False';
  2279 
  2280 * HOLCF/IOA replaces old HOL/IOA;
  2281 
  2282 * HOLCF changes: derived all rules and arities
  2283   + axiomatic type classes instead of classes
  2284   + typedef instead of faking type definitions
  2285   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2286   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2287   + eliminated the types void, one, tr
  2288   + use unit lift and bool lift (with translations) instead of one and tr
  2289   + eliminated blift from Lift3.thy (use Def instead of blift)
  2290   all eliminated rules are derived as theorems --> no visible changes ;
  2291 
  2292 
  2293 *** ZF ***
  2294 
  2295 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2296 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2297 as ZF_cs addSIs [equalityI];
  2298 
  2299 
  2300 
  2301 New in Isabelle94-7 (November 96)
  2302 ---------------------------------
  2303 
  2304 * allowing negative levels (as offsets) in prlev and choplev;
  2305 
  2306 * super-linear speedup for large simplifications;
  2307 
  2308 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2309 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2310 FAIL); can suppress it using the command Delsimps (ex_simps @
  2311 all_simps); De Morgan laws are also now included, by default;
  2312 
  2313 * improved printing of ==>  :  ~:
  2314 
  2315 * new object-logic "Sequents" adds linear logic, while replacing LK
  2316 and Modal (thanks to Sara Kalvala);
  2317 
  2318 * HOL/Auth: correctness proofs for authentication protocols;
  2319 
  2320 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2321 examples on HOL/Auth);
  2322 
  2323 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2324 the rewriter and classical reasoner simultaneously;
  2325 
  2326 * function uresult no longer returns theorems in "standard" format;
  2327 regain previous version by: val uresult = standard o uresult;
  2328 
  2329 
  2330 
  2331 New in Isabelle94-6
  2332 -------------------
  2333 
  2334 * oracles -- these establish an interface between Isabelle and trusted
  2335 external reasoners, which may deliver results as theorems;
  2336 
  2337 * proof objects (in particular record all uses of oracles);
  2338 
  2339 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2340 
  2341 * "constdefs" section in theory files;
  2342 
  2343 * "primrec" section (HOL) no longer requires names;
  2344 
  2345 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2346 
  2347 
  2348 
  2349 New in Isabelle94-5
  2350 -------------------
  2351 
  2352 * reduced space requirements;
  2353 
  2354 * automatic HTML generation from theories;
  2355 
  2356 * theory files no longer require "..." (quotes) around most types;
  2357 
  2358 * new examples, including two proofs of the Church-Rosser theorem;
  2359 
  2360 * non-curried (1994) version of HOL is no longer distributed;
  2361 
  2362 
  2363 
  2364 New in Isabelle94-4
  2365 -------------------
  2366 
  2367 * greatly reduced space requirements;
  2368 
  2369 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2370 
  2371 * searchable theorem database (see the section "Retrieving theorems" on
  2372 page 8 of the Reference Manual);
  2373 
  2374 * new examples, including Grabczewski's monumental case study of the
  2375 Axiom of Choice;
  2376 
  2377 * The previous version of HOL renamed to Old_HOL;
  2378 
  2379 * The new version of HOL (previously called CHOL) uses a curried syntax
  2380 for functions.  Application looks like f a b instead of f(a,b);
  2381 
  2382 * Mutually recursive inductive definitions finally work in HOL;
  2383 
  2384 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2385 translates to the operator "split";
  2386 
  2387 
  2388 
  2389 New in Isabelle94-3
  2390 -------------------
  2391 
  2392 * new infix operator, addss, allowing the classical reasoner to
  2393 perform simplification at each step of its search.  Example:
  2394         fast_tac (cs addss ss)
  2395 
  2396 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2397 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2398 look like (a,b) instead of <a,b>;
  2399 
  2400 * PLEASE NOTE: CHOL will eventually replace HOL!
  2401 
  2402 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2403 It translates to the operator "split".  A new theory of integers is available;
  2404 
  2405 * In ZF, integer numerals now denote two's-complement binary integers.
  2406 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2407 
  2408 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2409 of the Axiom of Choice;
  2410 
  2411 
  2412 
  2413 New in Isabelle94-2
  2414 -------------------
  2415 
  2416 * Significantly faster resolution;
  2417 
  2418 * the different sections in a .thy file can now be mixed and repeated
  2419 freely;
  2420 
  2421 * Database of theorems for FOL, HOL and ZF.  New
  2422 commands including qed, qed_goal and bind_thm store theorems in the database.
  2423 
  2424 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2425 a given theory (thms_of), or find out what theory a theorem was proved in
  2426 (theory_of_thm);
  2427 
  2428 * Bugs fixed in the inductive definition and datatype packages;
  2429 
  2430 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2431 and HOL_dup_cs obsolete;
  2432 
  2433 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2434 have been removed;
  2435 
  2436 * Simpler definition of function space in ZF;
  2437 
  2438 * new results about cardinal and ordinal arithmetic in ZF;
  2439 
  2440 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2441 types;
  2442 
  2443 
  2444 $Id$