NEWS
author paulson
Mon Jul 21 13:02:07 2003 +0200 (2003-07-21)
changeset 14120 3a73850c6c7d
parent 14119 fb9c392644a1
child 14136 9b7a62788dac
permissions -rw-r--r--
Tidied some examples
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** General ***
     8 
     9 * Provers/simplifier:
    10 
    11   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
    12     Assumptions are now subject to complete mutual simplification,
    13     not just from left to right. The simplifier now preserves
    14     the order of assumptions.
    15 
    16     Potential INCOMPATIBILITY:
    17 
    18     -- simp sometimes diverges where the old version did
    19        not, e.g. invoking simp on the goal
    20 
    21         [| P (f x); y = x; f x = f y |] ==> Q
    22 
    23        now gives rise to the infinite reduction sequence
    24 
    25         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
    26 
    27        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
    28        kind of problem.
    29 
    30     -- Tactics combining classical reasoner and simplification (such as auto)
    31        are also affected by this change, because many of them rely on
    32        simp. They may sometimes diverge as well or yield a different numbers
    33        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
    34        in case of problems. Sometimes subsequent calls to the classical
    35        reasoner will fail because a preceeding call to the simplifier too
    36        eagerly simplified the goal, e.g. deleted redundant premises.
    37 
    38   - The simplifier trace now shows the names of the applied rewrite rules
    39 
    40   - You can limit the number of recursive invocations of the simplifier
    41     during conditional rewriting (where the simplifie tries to solve the
    42     conditions before applying the rewrite rule):
    43     ML "simp_depth_limit := n"
    44     where n is an integer. Thus you can force termination where previously
    45     the simplifier would diverge.
    46 
    47   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
    48 
    49   - No longer aborts on failed congruence proof.  Instead, the
    50     congruence is ignored.
    51 
    52 * Pure: New generic framework for extracting programs from constructive
    53   proofs. See HOL/Extraction.thy for an example instantiation, as well
    54   as HOL/Extraction for some case studies.
    55 
    56 * Pure: The main goal of the proof state is no longer shown by default, only
    57 the subgoals. This behaviour is controlled by a new flag.
    58    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
    59 (ML: Proof.show_main_goal).
    60 
    61 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
    62 rules whose conclusion matches subgoal 1:
    63       PG menu: Isabelle/Isar -> Show me -> matching rules
    64 The rules are ordered by how closely they match the subgoal.
    65 In particular, rules that solve a subgoal outright are displayed first
    66 (or rather last, the way they are printed).
    67 (ML: ProofGeneral.print_intros())
    68 
    69 * Pure: New flag trace_unify_fail causes unification to print
    70 diagnostic information (PG: in trace buffer) when it fails. This is
    71 useful for figuring out why single step proofs like rule, erule or
    72 assumption failed.
    73 
    74 * Pure: Locale specifications now produce predicate definitions
    75 according to the body of text (covering assumptions modulo local
    76 definitions); predicate "loc_axioms" covers newly introduced text,
    77 while "loc" is cumulative wrt. all included locale expressions; the
    78 latter view is presented only on export into the global theory
    79 context; potential INCOMPATIBILITY, use "(open)" option to fall back
    80 on the old view without predicates;
    81 
    82 * Pure: predefined locales "var" and "struct" are useful for sharing
    83 parameters (as in CASL, for example); just specify something like
    84 ``var x + var y + struct M'' as import;
    85 
    86 * Pure: improved thms_containing: proper indexing of facts instead of
    87 raw theorems; check validity of results wrt. current name space;
    88 include local facts of proof configuration (also covers active
    89 locales), cover fixed variables in index; may use "_" in term
    90 specification; an optional limit for the number of printed facts may
    91 be given (the default is 40);
    92 
    93 * Pure: disallow duplicate fact bindings within new-style theory files
    94 (batch-mode only);
    95 
    96 * Provers: improved induct method: assumptions introduced by case
    97 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
    98 the goal statement); "foo" still refers to all facts collectively;
    99 
   100 * Provers: the function blast.overloaded has been removed: all constants
   101 are regarded as potentially overloaded, which improves robustness in exchange
   102 for slight decrease in efficiency;
   103 
   104 * Provers/linorder: New generic prover for transitivity reasoning over
   105 linear orders.  Note: this prover is not efficient!
   106 
   107 * Isar: preview of problems to finish 'show' now produce an error
   108 rather than just a warning (in interactive mode);
   109 
   110 
   111 *** HOL ***
   112 
   113 * 'specification' command added, allowing for definition by
   114 specification.
   115 
   116 * arith(_tac)
   117 
   118  - Produces a counter example if it cannot prove a goal.
   119    Note that the counter example may be spurious if the goal is not a formula
   120    of quantifier-free linear arithmetic.
   121    In ProofGeneral the counter example appears in the trace buffer.
   122 
   123  - Knows about div k and mod k where k is a numeral of type nat or int.
   124 
   125  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   126    linear arithmetic fails. This takes account of quantifiers and divisibility.
   127    Presburger arithmetic can also be called explicitly via presburger(_tac). 
   128 
   129 * simp's arithmetic capabilities have been enhanced a bit: it now
   130 takes ~= in premises into account (by performing a case split);
   131 
   132 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   133 are distributed over a sum of terms;
   134 
   135 * New tactic "trans_tac" and method "trans" instantiate
   136 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   137 "<=", "<" and "="). 
   138 
   139 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main 
   140 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   141 
   142 * 'typedef' command has new option "open" to suppress the set
   143 definition;
   144 
   145 * functions Min and Max on finite sets have been introduced (theory
   146 Finite_Set);
   147 
   148 * attribute [symmetric] now works for relations as well; it turns
   149 (x,y) : R^-1 into (y,x) : R, and vice versa;
   150 
   151 * induct over a !!-quantified statement (say !!x1..xn):
   152   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   153 
   154 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   155 %x. None. Warning: empty_def now refers to the previously hidden definition
   156 of the empty set.
   157 
   158 * Algebra: formalization of classical algebra.  Intended as base for
   159 any algebraic development in Isabelle.  Currently covers group theory
   160 (up to Sylow's theorem) and ring theory (Universal Property of
   161 Univariate Polynomials).  Contributions welcome;
   162 
   163 * GroupTheory: deleted, since its material has been moved to Algebra;
   164 
   165 * Complex: new directory of the complex numbers with numeric constants, 
   166 nonstandard complex numbers, and some complex analysis, standard and 
   167 nonstandard (Jacques Fleuriot);
   168 
   169 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   170 
   171 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques 
   172 Fleuriot);
   173 
   174 * Real/HahnBanach: updated and adapted to locales;
   175 
   176 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   177 Gray and Kramer);
   178 
   179 * UNITY: added the Meier-Sanders theory of progress sets;
   180 
   181 * MicroJava: bytecode verifier and lightweight bytecode verifier
   182 as abstract algorithms, instantiated to the JVM;
   183 
   184 * Bali: Java source language formalization. Type system, operational
   185 semantics, axiomatic semantics. Supported language features:
   186 classes, interfaces, objects,virtual methods, static methods,
   187 static/instance fields, arrays, access modifiers, definite
   188 assignment, exceptions.
   189 
   190 
   191 *** ZF ***
   192 
   193 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   194 universe, etc.);
   195 
   196 * Main ZF: virtually all theories converted to new-style format;
   197 
   198 
   199 *** ML ***
   200 
   201 * Pure: Tactic.prove provides sane interface for internal proofs;
   202 omits the infamous "standard" operation, so this is more appropriate
   203 than prove_goalw_cterm in many situations (e.g. in simprocs);
   204 
   205 * Pure: improved error reporting of simprocs;
   206 
   207 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   208 up simprocs;
   209 
   210 
   211 *** Document preparation ***
   212 
   213 * uses \par instead of \\ for line breaks in theory text. This may
   214 shift some page breaks in large documents. To get the old behaviour
   215 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   216 
   217 * minimized dependencies of isabelle.sty and isabellesym.sty on 
   218 other packages
   219 
   220 * \<euro> now needs package babel/greek instead of marvosym (which
   221 broke \Rightarrow)
   222 
   223 * normal size for \<zero>...\<nine> (uses \mathbf instead of 
   224 textcomp package)
   225 
   226 
   227 New in Isabelle2002 (March 2002)
   228 --------------------------------
   229 
   230 *** Document preparation ***
   231 
   232 * greatly simplified document preparation setup, including more
   233 graceful interpretation of isatool usedir -i/-d/-D options, and more
   234 instructive isatool mkdir; users should basically be able to get
   235 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   236 users may run a separate document processing stage manually like this:
   237 "isatool usedir -D output HOL Test && isatool document Test/output";
   238 
   239 * theory dependency graph may now be incorporated into documents;
   240 isatool usedir -g true will produce session_graph.eps/.pdf for use
   241 with \includegraphics of LaTeX;
   242 
   243 * proper spacing of consecutive markup elements, especially text
   244 blocks after section headings;
   245 
   246 * support bold style (for single symbols only), input syntax is like
   247 this: "\<^bold>\<alpha>" or "\<^bold>A";
   248 
   249 * \<bullet> is now output as bold \cdot by default, which looks much
   250 better in printed text;
   251 
   252 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   253 note that these symbols are currently unavailable in Proof General /
   254 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   255 
   256 * isatool latex no longer depends on changed TEXINPUTS, instead
   257 isatool document copies the Isabelle style files to the target
   258 location;
   259 
   260 
   261 *** Isar ***
   262 
   263 * Pure/Provers: improved proof by cases and induction;
   264   - 'case' command admits impromptu naming of parameters (such as
   265     "case (Suc n)");
   266   - 'induct' method divinates rule instantiation from the inductive
   267     claim; no longer requires excessive ?P bindings for proper
   268     instantiation of cases;
   269   - 'induct' method properly enumerates all possibilities of set/type
   270     rules; as a consequence facts may be also passed through *type*
   271     rules without further ado;
   272   - 'induct' method now derives symbolic cases from the *rulified*
   273     rule (before it used to rulify cases stemming from the internal
   274     atomized version); this means that the context of a non-atomic
   275     statement becomes is included in the hypothesis, avoiding the
   276     slightly cumbersome show "PROP ?case" form;
   277   - 'induct' may now use elim-style induction rules without chaining
   278     facts, using ``missing'' premises from the goal state; this allows
   279     rules stemming from inductive sets to be applied in unstructured
   280     scripts, while still benefitting from proper handling of non-atomic
   281     statements; NB: major inductive premises need to be put first, all
   282     the rest of the goal is passed through the induction;
   283   - 'induct' proper support for mutual induction involving non-atomic
   284     rule statements (uses the new concept of simultaneous goals, see
   285     below);
   286   - append all possible rule selections, but only use the first
   287     success (no backtracking);
   288   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   289   - undeclared rule case names default to numbers 1, 2, 3, ...;
   290   - added 'print_induct_rules' (covered by help item in recent Proof
   291     General versions);
   292   - moved induct/cases attributes to Pure, methods to Provers;
   293   - generic method setup instantiated for FOL and HOL;
   294 
   295 * Pure: support multiple simultaneous goal statements, for example
   296 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   297 meta-level mechanism, this acts as if several individual goals had
   298 been stated separately; in particular common proof methods need to be
   299 repeated in order to cover all claims; note that a single elimination
   300 step is *not* sufficient to establish the two conjunctions, so this
   301 fails:
   302 
   303   assume "A & B" then have A and B ..   (*".." fails*)
   304 
   305 better use "obtain" in situations as above; alternative refer to
   306 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   307 
   308 * Pure: proper integration with ``locales''; unlike the original
   309 version by Florian Kammüller, Isar locales package high-level proof
   310 contexts rather than raw logical ones (e.g. we admit to include
   311 attributes everywhere); operations on locales include merge and
   312 rename; support for implicit arguments (``structures''); simultaneous
   313 type-inference over imports and text; see also HOL/ex/Locales.thy for
   314 some examples;
   315 
   316 * Pure: the following commands have been ``localized'', supporting a
   317 target locale specification "(in name)": 'lemma', 'theorem',
   318 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   319 stored both within the locale and at the theory level (exported and
   320 qualified by the locale name);
   321 
   322 * Pure: theory goals may now be specified in ``long'' form, with
   323 ad-hoc contexts consisting of arbitrary locale elements. for example
   324 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   325 definitions may be given, too); the result is a meta-level rule with
   326 the context elements being discharged in the obvious way;
   327 
   328 * Pure: new proof command 'using' allows to augment currently used
   329 facts after a goal statement ('using' is syntactically analogous to
   330 'apply', but acts on the goal's facts only); this allows chained facts
   331 to be separated into parts given before and after a claim, as in
   332 ``from a and b have C using d and e <proof>'';
   333 
   334 * Pure: renamed "antecedent" case to "rule_context";
   335 
   336 * Pure: new 'judgment' command records explicit information about the
   337 object-logic embedding (used by several tools internally); no longer
   338 use hard-wired "Trueprop";
   339 
   340 * Pure: added 'corollary' command;
   341 
   342 * Pure: fixed 'token_translation' command;
   343 
   344 * Pure: removed obsolete 'exported' attribute;
   345 
   346 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   347 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   348 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   349 
   350 * Pure: method 'atomize' presents local goal premises as object-level
   351 statements (atomic meta-level propositions); setup controlled via
   352 rewrite rules declarations of 'atomize' attribute; example
   353 application: 'induct' method with proper rule statements in improper
   354 proof *scripts*;
   355 
   356 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   357 now consider the syntactic context of assumptions, giving a better
   358 chance to get type-inference of the arguments right (this is
   359 especially important for locales);
   360 
   361 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   362 mode;
   363 
   364 * Pure/obtain: the formal conclusion "thesis", being marked as
   365 ``internal'', may no longer be reference directly in the text;
   366 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   367 situations;
   368 
   369 * Pure: generic 'sym' attribute which declares a rule both as pure
   370 'elim?' and for the 'symmetric' operation;
   371 
   372 * Pure: marginal comments ``--'' may now occur just anywhere in the
   373 text; the fixed correlation with particular command syntax has been
   374 discontinued;
   375 
   376 * Pure: new method 'rules' is particularly well-suited for proof
   377 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   378 but often produces more compact proof terms with less detours;
   379 
   380 * Pure/Provers/classical: simplified integration with pure rule
   381 attributes and methods; the classical "intro?/elim?/dest?"
   382 declarations coincide with the pure ones; the "rule" method no longer
   383 includes classically swapped intros; "intro" and "elim" methods no
   384 longer pick rules from the context; also got rid of ML declarations
   385 AddXIs/AddXEs/AddXDs; all of this has some potential for
   386 INCOMPATIBILITY;
   387 
   388 * Provers/classical: attribute 'swapped' produces classical inversions
   389 of introduction rules;
   390 
   391 * Provers/simplifier: 'simplified' attribute may refer to explicit
   392 rules instead of full simplifier context; 'iff' attribute handles
   393 conditional rules;
   394 
   395 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   396 
   397 * HOL: 'recdef' now fails on unfinished automated proofs, use
   398 "(permissive)" option to recover old behavior;
   399 
   400 * HOL: 'inductive' no longer features separate (collective) attributes
   401 for 'intros' (was found too confusing);
   402 
   403 * HOL: properly declared induction rules less_induct and
   404 wf_induct_rule;
   405 
   406 
   407 *** HOL ***
   408 
   409 * HOL: moved over to sane numeral syntax; the new policy is as
   410 follows:
   411 
   412   - 0 and 1 are polymorphic constants, which are defined on any
   413   numeric type (nat, int, real etc.);
   414 
   415   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   416   binary representation internally;
   417 
   418   - type nat has special constructor Suc, and generally prefers Suc 0
   419   over 1::nat and Suc (Suc 0) over 2::nat;
   420 
   421 This change may cause significant problems of INCOMPATIBILITY; here
   422 are some hints on converting existing sources:
   423 
   424   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   425   entities, so expressions involving "-" (unary or binary minus) need
   426   to be spaced properly;
   427 
   428   - existing occurrences of "1" may need to be constraint "1::nat" or
   429   even replaced by Suc 0; similar for old "2";
   430 
   431   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   432 
   433   - remove all special provisions on numerals in proofs;
   434 
   435 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   436 representation (depends on bin_arith_simps in the default context);
   437 
   438 * HOL: symbolic syntax for x^2 (numeral 2);
   439 
   440 * HOL: the class of all HOL types is now called "type" rather than
   441 "term"; INCOMPATIBILITY, need to adapt references to this type class
   442 in axclass/classes, instance/arities, and (usually rare) occurrences
   443 in typings (of consts etc.); internally the class is called
   444 "HOL.type", ML programs should refer to HOLogic.typeS;
   445 
   446 * HOL/record package improvements:
   447   - new derived operations "fields" to build a partial record section,
   448     "extend" to promote a fixed record to a record scheme, and
   449     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   450     declared as simp by default;
   451   - shared operations ("more", "fields", etc.) now need to be always
   452     qualified) --- potential INCOMPATIBILITY;
   453   - removed "make_scheme" operations (use "make" with "extend") --
   454     INCOMPATIBILITY;
   455   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   456   - provides cases/induct rules for use with corresponding Isar
   457     methods (for concrete records, record schemes, concrete more
   458     parts, and schematic more parts -- in that order);
   459   - internal definitions directly based on a light-weight abstract
   460     theory of product types over typedef rather than datatype;
   461 
   462 * HOL: generic code generator for generating executable ML code from
   463 specifications; specific support for HOL constructs such as inductive
   464 datatypes and sets, as well as recursive functions; can be invoked
   465 via 'generate_code' theory section;
   466 
   467 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   468 
   469 * HOL: consolidated and renamed several theories.  In particular:
   470 	Ord.thy has been absorbed into HOL.thy
   471 	String.thy has been absorbed into List.thy
   472  
   473 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   474 (beware of argument permutation!);
   475 
   476 * HOL: linorder_less_split superseded by linorder_cases;
   477 
   478 * HOL/List: "nodups" renamed to "distinct";
   479 
   480 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   481 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   482   - Ex_def has changed, now need to use some_eq_ex
   483 
   484 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   485 in this (rare) case use:
   486 
   487   delSWrapper "split_all_tac"
   488   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   489 
   490 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   491 MAY FAIL;
   492 
   493 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   494 Isabelle's type classes, ^ on functions and relations has too general
   495 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   496 necessary to attach explicit type constraints;
   497 
   498 * HOL/Relation: the prefix name of the infix "O" has been changed from
   499 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   500 renamed accordingly (eg "compI" -> "rel_compI").
   501 
   502 * HOL: syntax translations now work properly with numerals and records
   503 expressions;
   504 
   505 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   506 of "lam" -- INCOMPATIBILITY;
   507 
   508 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   509 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   510 renamed "Product_Type.unit";
   511 
   512 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   513 
   514 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   515 the "cases" method);
   516 
   517 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   518 Florian Kammüller);
   519 
   520 * HOL/IMP: updated and converted to new-style theory format; several
   521 parts turned into readable document, with proper Isar proof texts and
   522 some explanations (by Gerwin Klein);
   523 
   524 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   525 
   526 * HOL-Hyperreal is now a logic image;
   527 
   528 
   529 *** HOLCF ***
   530 
   531 * Isar: consts/constdefs supports mixfix syntax for continuous
   532 operations;
   533 
   534 * Isar: domain package adapted to new-style theory format, e.g. see
   535 HOLCF/ex/Dnat.thy;
   536 
   537 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   538 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   539 lift.induct_tac, always use UU instead of Undef;
   540 
   541 * HOLCF/IMP: updated and converted to new-style theory;
   542 
   543 
   544 *** ZF ***
   545 
   546 * Isar: proper integration of logic-specific tools and packages,
   547 including theory commands '(co)inductive', '(co)datatype',
   548 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   549 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   550 
   551 * theory Main no longer includes AC; for the Axiom of Choice, base
   552 your theory on Main_ZFC;
   553 
   554 * the integer library now covers quotients and remainders, with many
   555 laws relating division to addition, multiplication, etc.;
   556 
   557 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   558 typeless version of the formalism;
   559 
   560 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   561 format;
   562 
   563 * ZF/Induct: new directory for examples of inductive definitions,
   564 including theory Multiset for multiset orderings; converted to
   565 new-style theory format;
   566 
   567 * ZF: many new theorems about lists, ordinals, etc.;
   568 
   569 
   570 *** General ***
   571 
   572 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   573 variable proof controls level of detail: 0 = no proofs (only oracle
   574 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   575 also ref manual for further ML interfaces;
   576 
   577 * Pure/axclass: removed obsolete ML interface
   578 goal_subclass/goal_arity;
   579 
   580 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   581 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   582 separate tokens, so expressions involving minus need to be spaced
   583 properly;
   584 
   585 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   586 rather than "infixl" or "infixr";
   587 
   588 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   589 sort constraint specifications in type inference; e.g. "x::_::foo"
   590 ensures that the type of "x" is of sort "foo" (but not necessarily a
   591 type variable);
   592 
   593 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   594 control output of nested => (types); the default behavior is
   595 "type_brackets";
   596 
   597 * Pure/syntax: builtin parse translation for "_constify" turns valued
   598 tokens into AST constants;
   599 
   600 * Pure/syntax: prefer later declarations of translations and print
   601 translation functions; potential INCOMPATIBILITY: need to reverse
   602 multiple declarations for same syntax element constant;
   603 
   604 * Pure/show_hyps reset by default (in accordance to existing Isar
   605 practice);
   606 
   607 * Provers/classical: renamed addaltern to addafter, addSaltern to
   608 addSafter;
   609 
   610 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   611 as well;
   612 
   613 * system: tested support for MacOS X; should be able to get Isabelle +
   614 Proof General to work in a plain Terminal after installing Poly/ML
   615 (e.g. from the Isabelle distribution area) and GNU bash alone
   616 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   617 support requires further installations, e.g. from
   618 http://fink.sourceforge.net/);
   619 
   620 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   621 
   622 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   623 of 40 MB), cf. ML_OPTIONS;
   624 
   625 * system: Proof General keywords specification is now part of the
   626 Isabelle distribution (see etc/isar-keywords.el);
   627 
   628 * system: support for persistent Proof General sessions (refrain from
   629 outdating all loaded theories on startup); user may create writable
   630 logic images like this: ``isabelle -q HOL Test'';
   631 
   632 * system: smart selection of Isabelle process versus Isabelle
   633 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   634 run both "isabelle" and "Isabelle" even if file names are badly
   635 damaged (executable inspects the case of the first letter of its own
   636 name); added separate "isabelle-process" and "isabelle-interface";
   637 
   638 * system: refrain from any attempt at filtering input streams; no
   639 longer support ``8bit'' encoding of old isabelle font, instead proper
   640 iso-latin characters may now be used; the related isatools
   641 "symbolinput" and "nonascii" have disappeared as well;
   642 
   643 * system: removed old "xterm" interface (the print modes "xterm" and
   644 "xterm_color" are still available for direct use in a suitable
   645 terminal);
   646 
   647 
   648 
   649 New in Isabelle99-2 (February 2001)
   650 -----------------------------------
   651 
   652 *** Overview of INCOMPATIBILITIES ***
   653 
   654 * HOL: please note that theories in the Library and elsewhere often use the
   655 new-style (Isar) format; to refer to their theorems in an ML script you must
   656 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   657 
   658 * HOL: inductive package no longer splits induction rule aggressively,
   659 but only as far as specified by the introductions given; the old
   660 format may be recovered via ML function complete_split_rule or attribute
   661 'split_rule (complete)';
   662 
   663 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   664 gfp_Tarski to gfp_unfold;
   665 
   666 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   667 
   668 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   669 relation); infix "^^" has been renamed "``"; infix "``" has been
   670 renamed "`"; "univalent" has been renamed "single_valued";
   671 
   672 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   673 operation;
   674 
   675 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   676 
   677 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   678 
   679 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   680 consequence, it is no longer monotonic wrt. the local goal context
   681 (which is now passed through the inductive cases);
   682 
   683 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   684 \<gg> to \<ggreater>;
   685 
   686 
   687 *** Document preparation ***
   688 
   689 * \isabellestyle{NAME} selects version of Isabelle output (currently
   690 available: are "it" for near math-mode best-style output, "sl" for
   691 slanted text style, and "tt" for plain type-writer; if no
   692 \isabellestyle command is given, output is according to slanted
   693 type-writer);
   694 
   695 * support sub/super scripts (for single symbols only), input syntax is
   696 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   697 
   698 * some more standard symbols; see Appendix A of the system manual for
   699 the complete list of symbols defined in isabellesym.sty;
   700 
   701 * improved isabelle style files; more abstract symbol implementation
   702 (should now use \isamath{...} and \isatext{...} in custom symbol
   703 definitions);
   704 
   705 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   706 state; Note that presentation of goal states does not conform to
   707 actual human-readable proof documents.  Please do not include goal
   708 states into document output unless you really know what you are doing!
   709 
   710 * proper indentation of antiquoted output with proportional LaTeX
   711 fonts;
   712 
   713 * no_document ML operator temporarily disables LaTeX document
   714 generation;
   715 
   716 * isatool unsymbolize tunes sources for plain ASCII communication;
   717 
   718 
   719 *** Isar ***
   720 
   721 * Pure: Isar now suffers initial goal statements to contain unbound
   722 schematic variables (this does not conform to actual readable proof
   723 documents, due to unpredictable outcome and non-compositional proof
   724 checking); users who know what they are doing may use schematic goals
   725 for Prolog-style synthesis of proven results;
   726 
   727 * Pure: assumption method (an implicit finishing) now handles actual
   728 rules as well;
   729 
   730 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   731 initial goal, declare "that" only as Pure intro (only for single
   732 steps); the "that" rule assumption may now be involved in implicit
   733 finishing, thus ".." becomes a feasible for trivial obtains;
   734 
   735 * Pure: default proof step now includes 'intro_classes'; thus trivial
   736 instance proofs may be performed by "..";
   737 
   738 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   739 statements as well;
   740 
   741 * Pure: more robust selection of calculational rules;
   742 
   743 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   744 rule (as well as the assumption rule);
   745 
   746 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   747 lemmas, using the graph browser tool;
   748 
   749 * Pure: predict failure of "show" in interactive mode;
   750 
   751 * Pure: 'thms_containing' now takes actual terms as arguments;
   752 
   753 * HOL: improved method 'induct' --- now handles non-atomic goals
   754 (potential INCOMPATIBILITY); tuned error handling;
   755 
   756 * HOL: cases and induct rules now provide explicit hints about the
   757 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   758 any remaining facts are inserted into the goal verbatim;
   759 
   760 * HOL: local contexts (aka cases) may now contain term bindings as
   761 well; the 'cases' and 'induct' methods new provide a ?case binding for
   762 the result to be shown in each case;
   763 
   764 * HOL: added 'recdef_tc' command;
   765 
   766 * isatool convert assists in eliminating legacy ML scripts;
   767 
   768 
   769 *** HOL ***
   770 
   771 * HOL/Library: a collection of generic theories to be used together
   772 with main HOL; the theory loader path already includes this directory
   773 by default; the following existing theories have been moved here:
   774 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   775 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   776 
   777 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   778 modelling and verification task performed in Isabelle/HOL +
   779 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   780 
   781 * HOL/Algebra: special summation operator SUM no longer exists, it has
   782 been replaced by setsum; infix 'assoc' now has priority 50 (like
   783 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   784 'domain', this makes the theory consistent with mathematical
   785 literature;
   786 
   787 * HOL basics: added overloaded operations "inverse" and "divide"
   788 (infix "/"), syntax for generic "abs" operation, generic summation
   789 operator \<Sum>;
   790 
   791 * HOL/typedef: simplified package, provide more useful rules (see also
   792 HOL/subset.thy);
   793 
   794 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   795 now expressed as a proper nested rule (old-style tactic scripts may
   796 require atomize_strip_tac to cope with non-atomic premises);
   797 
   798 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   799 to "split_conv" (old name still available for compatibility);
   800 
   801 * HOL: improved concrete syntax for strings (e.g. allows translation
   802 rules with string literals);
   803 
   804 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   805  and Fleuriot's mechanization of analysis, including the transcendental
   806  functions for the reals;
   807 
   808 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   809 
   810 
   811 *** CTT ***
   812 
   813 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   814 "lam" is displayed as TWO lambda-symbols
   815 
   816 * CTT: theory Main now available, containing everything (that is, Bool
   817 and Arith);
   818 
   819 
   820 *** General ***
   821 
   822 * Pure: the Simplifier has been implemented properly as a derived rule
   823 outside of the actual kernel (at last!); the overall performance
   824 penalty in practical applications is about 50%, while reliability of
   825 the Isabelle inference kernel has been greatly improved;
   826 
   827 * print modes "brackets" and "no_brackets" control output of nested =>
   828 (types) and ==> (props); the default behaviour is "brackets";
   829 
   830 * Provers: fast_tac (and friends) now handle actual object-logic rules
   831 as assumptions as well;
   832 
   833 * system: support Poly/ML 4.0;
   834 
   835 * system: isatool install handles KDE version 1 or 2;
   836 
   837 
   838 
   839 New in Isabelle99-1 (October 2000)
   840 ----------------------------------
   841 
   842 *** Overview of INCOMPATIBILITIES ***
   843 
   844 * HOL: simplification of natural numbers is much changed; to partly
   845 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   846 issue the following ML commands:
   847 
   848   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   849   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   850 
   851 * HOL: simplification no longer dives into case-expressions; this is
   852 controlled by "t.weak_case_cong" for each datatype t;
   853 
   854 * HOL: nat_less_induct renamed to less_induct;
   855 
   856 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   857 fixsome to patch .thy and .ML sources automatically;
   858 
   859   select_equality  -> some_equality
   860   select_eq_Ex     -> some_eq_ex
   861   selectI2EX       -> someI2_ex
   862   selectI2         -> someI2
   863   selectI          -> someI
   864   select1_equality -> some1_equality
   865   Eps_sym_eq       -> some_sym_eq_trivial
   866   Eps_eq           -> some_eq_trivial
   867 
   868 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   869 
   870 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   871 instead);
   872 
   873 * HOL: the recursion equations generated by 'recdef' are now called
   874 f.simps instead of f.rules;
   875 
   876 * HOL: qed_spec_mp now also handles bounded ALL as well;
   877 
   878 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   879 sometimes be needed;
   880 
   881 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   882 
   883 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   884 
   885 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   886 product is now "<*>" instead of "Times"; the lexicographic product is
   887 now "<*lex*>" instead of "**";
   888 
   889 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   890 of main HOL, but was unused); better use HOL's datatype package;
   891 
   892 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   893 the old syntax may be recovered as follows:
   894 
   895   syntax (symbols)
   896     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   897       (infixl "\\<oplus>" 100)
   898 
   899 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   900 
   901 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   902 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   903 internally;
   904 
   905 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   906 changed from A/r to A//r;
   907 
   908 * ZF: new treatment of arithmetic (nat & int) may break some old
   909 proofs;
   910 
   911 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   912 rulify -> rule_format, elimify -> elim_format, ...);
   913 
   914 * Isar/Provers: intro/elim/dest attributes changed; renamed
   915 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   916 should have to change intro!! to intro? only); replaced "delrule" by
   917 "rule del";
   918 
   919 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   920 
   921 * Provers: strengthened force_tac by using new first_best_tac;
   922 
   923 * LaTeX document preparation: several changes of isabelle.sty (see
   924 lib/texinputs);
   925 
   926 
   927 *** Document preparation ***
   928 
   929 * formal comments (text blocks etc.) in new-style theories may now
   930 contain antiquotations of thm/prop/term/typ/text to be presented
   931 according to latex print mode; concrete syntax is like this:
   932 @{term[show_types] "f(x) = a + x"};
   933 
   934 * isatool mkdir provides easy setup of Isabelle session directories,
   935 including proper document sources;
   936 
   937 * generated LaTeX sources are now deleted after successful run
   938 (isatool document -c); may retain a copy somewhere else via -D option
   939 of isatool usedir;
   940 
   941 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   942 style files, achieving self-contained LaTeX sources and simplifying
   943 LaTeX debugging;
   944 
   945 * old-style theories now produce (crude) LaTeX output as well;
   946 
   947 * browser info session directories are now self-contained (may be put
   948 on WWW server seperately); improved graphs of nested sessions; removed
   949 graph for 'all sessions';
   950 
   951 * several improvements in isabelle style files; \isabellestyle{it}
   952 produces fake math mode output; \isamarkupheader is now \section by
   953 default; see lib/texinputs/isabelle.sty etc.;
   954 
   955 
   956 *** Isar ***
   957 
   958 * Isar/Pure: local results and corresponding term bindings are now
   959 subject to Hindley-Milner polymorphism (similar to ML); this
   960 accommodates incremental type-inference very nicely;
   961 
   962 * Isar/Pure: new derived language element 'obtain' supports
   963 generalized existence reasoning;
   964 
   965 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   966 support accumulation of results, without applying any rules yet;
   967 useful to collect intermediate results without explicit name
   968 references, and for use with transitivity rules with more than 2
   969 premises;
   970 
   971 * Isar/Pure: scalable support for case-analysis type proofs: new
   972 'case' language element refers to local contexts symbolically, as
   973 produced by certain proof methods; internally, case names are attached
   974 to theorems as "tags";
   975 
   976 * Isar/Pure: theory command 'hide' removes declarations from
   977 class/type/const name spaces;
   978 
   979 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   980 indicate potential overloading;
   981 
   982 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   983 
   984 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   985 "{a,b,c}" instead of {a,b,c};
   986 
   987 * Isar/Pure now provides its own version of intro/elim/dest
   988 attributes; useful for building new logics, but beware of confusion
   989 with the version in Provers/classical;
   990 
   991 * Isar/Pure: the local context of (non-atomic) goals is provided via
   992 case name 'antecedent';
   993 
   994 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   995 to the current context is now done automatically);
   996 
   997 * Isar/Pure: theory command 'method_setup' provides a simple interface
   998 for definining proof methods in ML;
   999 
  1000 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1001 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1002 most cases, one should have to change intro!! to intro? only);
  1003 replaced "delrule" by "rule del";
  1004 
  1005 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1006 'symmetric' attribute (the latter supercedes [RS sym]);
  1007 
  1008 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1009 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1010 well (including splits);
  1011 
  1012 * Isar/Provers: Simplifier and Classical methods now support all kind
  1013 of modifiers used in the past, including 'cong', 'iff', etc.
  1014 
  1015 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1016 of Simplifier and Classical reasoner);
  1017 
  1018 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1019 now support named cases; major packages (inductive, datatype, primrec,
  1020 recdef) support case names and properly name parameters;
  1021 
  1022 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1023 monotonicity conditions are extracted to be proven at end of
  1024 calculations;
  1025 
  1026 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1027 method anyway;
  1028 
  1029 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1030 split_if split_if_asm; datatype package provides theorems foo.splits =
  1031 foo.split foo.split_asm for each datatype;
  1032 
  1033 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1034 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1035 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1036 use "(cases (simplified))" method in proper proof texts);
  1037 
  1038 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1039 
  1040 * Isar: names of theorems etc. may be natural numbers as well;
  1041 
  1042 * Isar: 'pr' command: optional arguments for goals_limit and
  1043 ProofContext.prems_limit; no longer prints theory contexts, but only
  1044 proof states;
  1045 
  1046 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1047 additional print modes to be specified; e.g. "pr(latex)" will print
  1048 proof state according to the Isabelle LaTeX style;
  1049 
  1050 * Isar: improved support for emulating tactic scripts, including proof
  1051 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1052 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1053 (for HOL datatypes);
  1054 
  1055 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1056 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1057 'proof method scripts' have to be in depth-first order;
  1058 
  1059 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1060 
  1061 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1062 should instead use individual commands for printing items
  1063 (print_commands, print_methods etc.);
  1064 
  1065 * Isar: added 'nothing' --- the empty list of theorems;
  1066 
  1067 
  1068 *** HOL ***
  1069 
  1070 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1071 corresponding virtual machine and a specification of its bytecode
  1072 verifier and a lightweight bytecode verifier, including proofs of
  1073 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1074 Cornelia Pusch (see also the homepage of project Bali at
  1075 http://isabelle.in.tum.de/Bali/);
  1076 
  1077 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1078 Clemens Ballarin;
  1079 
  1080 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1081 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1082 Rasmussen;
  1083 
  1084 * HOL/Lattice: fundamental concepts of lattice theory and order
  1085 structures, including duals, properties of bounds versus algebraic
  1086 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1087 Theorem for complete lattices etc.; may also serve as a demonstration
  1088 for abstract algebraic reasoning using axiomatic type classes, and
  1089 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1090 
  1091 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1092 von Oheimb;
  1093 
  1094 * HOL/IMPP: extension of IMP with local variables and mutually
  1095 recursive procedures, by David von Oheimb;
  1096 
  1097 * HOL/Lambda: converted into new-style theory and document;
  1098 
  1099 * HOL/ex/Multiquote: example of multiple nested quotations and
  1100 anti-quotations -- basically a generalized version of de-Bruijn
  1101 representation; very useful in avoiding lifting of operations;
  1102 
  1103 * HOL/record: added general record equality rule to simpset; fixed
  1104 select-update simplification procedure to handle extended records as
  1105 well; admit "r" as field name;
  1106 
  1107 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1108 other numeric types and also as the identity of groups, rings, etc.;
  1109 
  1110 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1111 Types nat and int belong to this axclass;
  1112 
  1113 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1114    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1115    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1116   two terms #m*u and #n*u are replaced by #(m+n)*u
  1117     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1118   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1119     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1120 
  1121 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1122 powerful prover for predicate logic but knows nothing of clasets; see
  1123 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1124 
  1125 * HOL: new version of "case_tac" subsumes both boolean case split and
  1126 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1127 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1128 
  1129 * HOL: simplification no longer dives into case-expressions: only the
  1130 selector expression is simplified, but not the remaining arms; to
  1131 enable full simplification of case-expressions for datatype t, you may
  1132 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1133 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1134 
  1135 * HOL/recdef: the recursion equations generated by 'recdef' for
  1136 function 'f' are now called f.simps instead of f.rules; if all
  1137 termination conditions are proved automatically, these simplification
  1138 rules are added to the simpset, as in primrec; rules may be named
  1139 individually as well, resulting in a separate list of theorems for
  1140 each equation;
  1141 
  1142 * HOL/While is a new theory that provides a while-combinator. It
  1143 permits the definition of tail-recursive functions without the
  1144 provision of a termination measure. The latter is necessary once the
  1145 invariant proof rule for while is applied.
  1146 
  1147 * HOL: new (overloaded) notation for the set of elements below/above
  1148 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1149 
  1150 * HOL: theorems impI, allI, ballI bound as "strip";
  1151 
  1152 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1153 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1154 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1155 
  1156 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1157 
  1158 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1159 main HOL, but was unused);
  1160 
  1161 * HOL: fewer consts declared as global (e.g. have to refer to
  1162 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1163 
  1164 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1165 in case of overlap with user translations (e.g. judgements over
  1166 tuples); (note that the underlying logical represenation is still
  1167 bogus);
  1168 
  1169 
  1170 *** ZF ***
  1171 
  1172 * ZF: simplification automatically cancels common terms in arithmetic
  1173 expressions over nat and int;
  1174 
  1175 * ZF: new treatment of nat to minimize type-checking: all operators
  1176 coerce their operands to a natural number using the function natify,
  1177 making the algebraic laws unconditional;
  1178 
  1179 * ZF: as above, for int: operators coerce their operands to an integer
  1180 using the function intify;
  1181 
  1182 * ZF: the integer library now contains many of the usual laws for the
  1183 orderings, including $<=, and monotonicity laws for $+ and $*;
  1184 
  1185 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1186 simplification;
  1187 
  1188 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1189 to the simplifier and classical reasoner simultaneously;
  1190 
  1191 
  1192 *** General ***
  1193 
  1194 * Provers: blast_tac now handles actual object-logic rules as
  1195 assumptions; note that auto_tac uses blast_tac internally as well;
  1196 
  1197 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1198 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1199 
  1200 * Provers: delrules now handles destruct rules as well (no longer need
  1201 explicit make_elim);
  1202 
  1203 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1204   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1205 use instead the strong form,
  1206   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1207 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1208 from destruct-rules;
  1209 
  1210 * Provers: Simplifier.easy_setup provides a fast path to basic
  1211 Simplifier setup for new object-logics;
  1212 
  1213 * Pure: AST translation rules no longer require constant head on LHS;
  1214 
  1215 * Pure: improved name spaces: ambiguous output is qualified; support
  1216 for hiding of names;
  1217 
  1218 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1219 XSYMBOL_HOME; no longer need to do manual configuration in most
  1220 situations;
  1221 
  1222 * system: compression of ML heaps images may now be controlled via -c
  1223 option of isabelle and isatool usedir (currently only observed by
  1224 Poly/ML);
  1225 
  1226 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1227 useful for remote X11);
  1228 
  1229 * system: provide TAGS file for Isabelle sources;
  1230 
  1231 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1232 order;
  1233 
  1234 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1235 timing flag supersedes proof_timing and Toplevel.trace;
  1236 
  1237 * ML: new combinators |>> and |>>> for incremental transformations
  1238 with secondary results (e.g. certain theory extensions):
  1239 
  1240 * ML: PureThy.add_defs gets additional argument to indicate potential
  1241 overloading (usually false);
  1242 
  1243 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1244 results;
  1245 
  1246 
  1247 
  1248 New in Isabelle99 (October 1999)
  1249 --------------------------------
  1250 
  1251 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1252 
  1253 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1254 are no longer simplified.  (This allows the simplifier to unfold recursive
  1255 functional programs.)  To restore the old behaviour, declare
  1256 
  1257     Delcongs [if_weak_cong];
  1258 
  1259 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1260 complement;
  1261 
  1262 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1263 
  1264 * HOL/datatype: mutual_induct_tac no longer exists --
  1265   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1266 
  1267 * HOL/typedef: fixed type inference for representing set; type
  1268 arguments now have to occur explicitly on the rhs as type constraints;
  1269 
  1270 * ZF: The con_defs part of an inductive definition may no longer refer
  1271 to constants declared in the same theory;
  1272 
  1273 * HOL, ZF: the function mk_cases, generated by the inductive
  1274 definition package, has lost an argument.  To simplify its result, it
  1275 uses the default simpset instead of a supplied list of theorems.
  1276 
  1277 * HOL/List: the constructors of type list are now Nil and Cons;
  1278 
  1279 * Simplifier: the type of the infix ML functions
  1280         setSSolver addSSolver setSolver addSolver
  1281 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1282 for packaging solvers. A solver is created via
  1283         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1284 where the string argument is only a comment.
  1285 
  1286 
  1287 *** Proof tools ***
  1288 
  1289 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1290 decision procedure for linear arithmetic. Currently it is used for
  1291 types `nat', `int', and `real' in HOL (see below); it can, should and
  1292 will be instantiated for other types and logics as well.
  1293 
  1294 * The simplifier now accepts rewrite rules with flexible heads, eg
  1295      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1296   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1297   matching.
  1298 
  1299 
  1300 *** General ***
  1301 
  1302 * New Isabelle/Isar subsystem provides an alternative to traditional
  1303 tactical theorem proving; together with the ProofGeneral/isar user
  1304 interface it offers an interactive environment for developing human
  1305 readable proof documents (Isar == Intelligible semi-automated
  1306 reasoning); for further information see isatool doc isar-ref,
  1307 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1308 
  1309 * improved and simplified presentation of theories: better HTML markup
  1310 (including colors), graph views in several sizes; isatool usedir now
  1311 provides a proper interface for user theories (via -P option); actual
  1312 document preparation based on (PDF)LaTeX is available as well (for
  1313 new-style theories only); see isatool doc system for more information;
  1314 
  1315 * native support for Proof General, both for classic Isabelle and
  1316 Isabelle/Isar;
  1317 
  1318 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1319 using the graph browser tool;
  1320 
  1321 * Isabelle manuals now also available as PDF;
  1322 
  1323 * theory loader rewritten from scratch (may not be fully
  1324 bug-compatible); old loadpath variable has been replaced by show_path,
  1325 add_path, del_path, reset_path functions; new operations such as
  1326 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1327 isatool doc ref);
  1328 
  1329 * improved isatool install: option -k creates KDE application icon,
  1330 option -p DIR installs standalone binaries;
  1331 
  1332 * added ML_PLATFORM setting (useful for cross-platform installations);
  1333 more robust handling of platform specific ML images for SML/NJ;
  1334 
  1335 * the settings environment is now statically scoped, i.e. it is never
  1336 created again in sub-processes invoked from isabelle, isatool, or
  1337 Isabelle;
  1338 
  1339 * path element specification '~~' refers to '$ISABELLE_HOME';
  1340 
  1341 * in locales, the "assumes" and "defines" parts may be omitted if
  1342 empty;
  1343 
  1344 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1345 long arrows);
  1346 
  1347 * new print_mode "HTML";
  1348 
  1349 * new flag show_tags controls display of tags of theorems (which are
  1350 basically just comments that may be attached by some tools);
  1351 
  1352 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1353 mode and goal output format:
  1354 
  1355 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1356 244c244
  1357 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1358 ---
  1359 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1360 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1361 181c181
  1362 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1363 ---
  1364 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1365 
  1366 * function bind_thms stores lists of theorems (cf. bind_thm);
  1367 
  1368 * new shorthand tactics ftac, eatac, datac, fatac;
  1369 
  1370 * qed (and friends) now accept "" as result name; in that case the
  1371 theorem is not stored, but proper checks and presentation of the
  1372 result still apply;
  1373 
  1374 * theorem database now also indexes constants "Trueprop", "all",
  1375 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1376 
  1377 
  1378 *** HOL ***
  1379 
  1380 ** HOL arithmetic **
  1381 
  1382 * There are now decision procedures for linear arithmetic over nat and
  1383 int:
  1384 
  1385 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1386 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1387 are treated as atomic; subformulae not involving type `nat' or `int'
  1388 are ignored; quantified subformulae are ignored unless they are
  1389 positive universal or negative existential. The tactic has to be
  1390 invoked by hand and can be a little bit slow. In particular, the
  1391 running time is exponential in the number of occurrences of `min' and
  1392 `max', and `-' on `nat'.
  1393 
  1394 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1395 (negated) (in)equalities among the premises and the conclusion into
  1396 account (i.e. no compound formulae) and does not know about `min' and
  1397 `max', and `-' on `nat'. It is fast and is used automatically by the
  1398 simplifier.
  1399 
  1400 NB: At the moment, these decision procedures do not cope with mixed
  1401 nat/int formulae where the two parts interact, such as `m < n ==>
  1402 int(m) < int(n)'.
  1403 
  1404 * HOL/Numeral provides a generic theory of numerals (encoded
  1405 efficiently as bit strings); setup for types nat/int/real is in place;
  1406 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1407 int, existing theories and proof scripts may require a few additional
  1408 type constraints;
  1409 
  1410 * integer division and remainder can now be performed on constant
  1411 arguments;
  1412 
  1413 * many properties of integer multiplication, division and remainder
  1414 are now available;
  1415 
  1416 * An interface to the Stanford Validity Checker (SVC) is available through the
  1417 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1418 are proved automatically.  SVC must be installed separately, and its results
  1419 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1420 invocation of the underlying oracle).  For SVC see
  1421   http://verify.stanford.edu/SVC
  1422 
  1423 * IsaMakefile: the HOL-Real target now builds an actual image;
  1424 
  1425 
  1426 ** HOL misc **
  1427 
  1428 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1429 (in Isabelle/Isar) -- by Gertrud Bauer;
  1430 
  1431 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1432 analysis for assembly languages with subtypes;
  1433 
  1434 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1435 -- avoids syntactic ambiguities and treats state, transition, and
  1436 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1437 changed syntax and (many) tactics;
  1438 
  1439 * HOL/inductive: Now also handles more general introduction rules such
  1440   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1441   theorems are now maintained within the theory (maintained via the
  1442   "mono" attribute);
  1443 
  1444 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1445   (using function types) such as
  1446 
  1447   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1448 
  1449 * HOL/record: record_simproc (part of the default simpset) takes care
  1450 of selectors applied to updated records; record_split_tac is no longer
  1451 part of the default claset; update_defs may now be removed from the
  1452 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1453 
  1454   claset_ref () := claset() addSWrapper record_split_wrapper;
  1455   Delsimprocs [record_simproc]
  1456 
  1457 * HOL/typedef: fixed type inference for representing set; type
  1458 arguments now have to occur explicitly on the rhs as type constraints;
  1459 
  1460 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1461 names rather than an ML expression;
  1462 
  1463 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1464 supplied later.  Program schemes can be defined, such as
  1465     "While B C s = (if B s then While B C (C s) else s)"
  1466 where the well-founded relation can be chosen after B and C have been given.
  1467 
  1468 * HOL/List: the constructors of type list are now Nil and Cons;
  1469 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1470 course, ML tools referring to List.list.op # etc. have to be adapted;
  1471 
  1472 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1473 disabled by default; run isabelle with option -m HOL to get back to
  1474 the original Gordon/HOL-style output;
  1475 
  1476 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1477 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1478 
  1479 * HOL basic syntax simplified (more orthogonal): all variants of
  1480 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1481 Eps operator is provided as well: "SOME x. P[x]";
  1482 
  1483 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1484 
  1485 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1486 thus available for user theories;
  1487 
  1488 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1489 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1490 time;
  1491 
  1492 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1493 several times and then mp;
  1494 
  1495 
  1496 *** LK ***
  1497 
  1498 * the notation <<...>> is now available as a notation for sequences of
  1499 formulas;
  1500 
  1501 * the simplifier is now installed
  1502 
  1503 * the axiom system has been generalized (thanks to Soren Heilmann)
  1504 
  1505 * the classical reasoner now has a default rule database
  1506 
  1507 
  1508 *** ZF ***
  1509 
  1510 * new primrec section allows primitive recursive functions to be given
  1511 directly (as in HOL) over datatypes and the natural numbers;
  1512 
  1513 * new tactics induct_tac and exhaust_tac for induction (or case
  1514 analysis) over datatypes and the natural numbers;
  1515 
  1516 * the datatype declaration of type T now defines the recursor T_rec;
  1517 
  1518 * simplification automatically does freeness reasoning for datatype
  1519 constructors;
  1520 
  1521 * automatic type-inference, with AddTCs command to insert new
  1522 type-checking rules;
  1523 
  1524 * datatype introduction rules are now added as Safe Introduction rules
  1525 to the claset;
  1526 
  1527 * the syntax "if P then x else y" is now available in addition to
  1528 if(P,x,y);
  1529 
  1530 
  1531 *** Internal programming interfaces ***
  1532 
  1533 * tuned simplifier trace output; new flag debug_simp;
  1534 
  1535 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1536 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1537 
  1538 * AxClass.axclass_tac lost the theory argument;
  1539 
  1540 * tuned current_goals_markers semantics: begin / end goal avoids
  1541 printing empty lines;
  1542 
  1543 * removed prs and prs_fn hook, which was broken because it did not
  1544 include \n in its semantics, forcing writeln to add one
  1545 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1546 string -> unit if you really want to output text without newline;
  1547 
  1548 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1549 plain output, interface builders may have to enable 'isabelle_font'
  1550 mode to get Isabelle font glyphs as before;
  1551 
  1552 * refined token_translation interface; INCOMPATIBILITY: output length
  1553 now of type real instead of int;
  1554 
  1555 * theory loader actions may be traced via new ThyInfo.add_hook
  1556 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1557 your own database of information attached to *whole* theories -- as
  1558 opposed to intra-theory data slots offered via TheoryDataFun;
  1559 
  1560 * proper handling of dangling sort hypotheses (at last!);
  1561 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1562 extra sort hypotheses that can be witnessed from the type signature;
  1563 the force_strip_shyps flag is gone, any remaining shyps are simply
  1564 left in the theorem (with a warning issued by strip_shyps_warning);
  1565 
  1566 
  1567 
  1568 New in Isabelle98-1 (October 1998)
  1569 ----------------------------------
  1570 
  1571 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1572 
  1573 * several changes of automated proof tools;
  1574 
  1575 * HOL: major changes to the inductive and datatype packages, including
  1576 some minor incompatibilities of theory syntax;
  1577 
  1578 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1579 called `inj_on';
  1580 
  1581 * HOL: removed duplicate thms in Arith:
  1582   less_imp_add_less  should be replaced by  trans_less_add1
  1583   le_imp_add_le      should be replaced by  trans_le_add1
  1584 
  1585 * HOL: unary minus is now overloaded (new type constraints may be
  1586 required);
  1587 
  1588 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1589 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1590 now taken as an integer constant.
  1591 
  1592 * Pure: ML function 'theory_of' renamed to 'theory';
  1593 
  1594 
  1595 *** Proof tools ***
  1596 
  1597 * Simplifier:
  1598   1. Asm_full_simp_tac is now more aggressive.
  1599      1. It will sometimes reorient premises if that increases their power to
  1600         simplify.
  1601      2. It does no longer proceed strictly from left to right but may also
  1602         rotate premises to achieve further simplification.
  1603      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1604      old Asm_full_simp_tac in that it does not rotate premises.
  1605   2. The simplifier now knows a little bit about nat-arithmetic.
  1606 
  1607 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1608 allows for selected deletion of wrappers, by introduction of names for
  1609 wrapper functionals.  This implies that addbefore, addSbefore,
  1610 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1611 and that adding two tactics with the same name overwrites the first
  1612 one (emitting a warning).
  1613   type wrapper = (int -> tactic) -> (int -> tactic)
  1614   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1615   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1616   delWrapper, delSWrapper: claset *  string            -> claset
  1617   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1618 
  1619 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1620 semantics; addbefore now affects only the unsafe part of step_tac
  1621 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1622 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1623 by Force_tac;
  1624 
  1625 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1626 compWrapper; added safe wrapper (and access functions for it);
  1627 
  1628 * HOL/split_all_tac is now much faster and fails if there is nothing
  1629 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1630 and the names of the automatically generated variables have changed.
  1631 split_all_tac has moved within claset() from unsafe wrappers to safe
  1632 wrappers, which means that !!-bound variables are split much more
  1633 aggressively, and safe_tac and clarify_tac now split such variables.
  1634 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1635 Note: the same holds for record_split_tac, which does the job of
  1636 split_all_tac for record fields.
  1637 
  1638 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1639 permanently to the default simpset using Addsplits just like
  1640 Addsimps. They can be removed via Delsplits just like
  1641 Delsimps. Lower-case versions are also available.
  1642 
  1643 * HOL/Simplifier: The rule split_if is now part of the default
  1644 simpset. This means that the simplifier will eliminate all occurrences
  1645 of if-then-else in the conclusion of a goal. To prevent this, you can
  1646 either remove split_if completely from the default simpset by
  1647 `Delsplits [split_if]' or remove it in a specific call of the
  1648 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1649 other case splitting rules to/from the default simpset: every datatype
  1650 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1651 t is the name of the datatype).
  1652 
  1653 * Classical reasoner / Simplifier combination: new force_tac (and
  1654 derivatives Force_tac, force) combines rewriting and classical
  1655 reasoning (and whatever other tools) similarly to auto_tac, but is
  1656 aimed to solve the given subgoal completely.
  1657 
  1658 
  1659 *** General ***
  1660 
  1661 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1662 and `goalw': the theory is no longer needed as an explicit argument -
  1663 the current theory context is used; assumptions are no longer returned
  1664 at the ML-level unless one of them starts with ==> or !!; it is
  1665 recommended to convert to these new commands using isatool fixgoal
  1666 (backup your sources first!);
  1667 
  1668 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1669 the current theory context, and 'theory' to lookup stored theories;
  1670 
  1671 * new theory section 'locale' for declaring constants, assumptions and
  1672 definitions that have local scope;
  1673 
  1674 * new theory section 'nonterminals' for purely syntactic types;
  1675 
  1676 * new theory section 'setup' for generic ML setup functions
  1677 (e.g. package initialization);
  1678 
  1679 * the distribution now includes Isabelle icons: see
  1680 lib/logo/isabelle-{small,tiny}.xpm;
  1681 
  1682 * isatool install - install binaries with absolute references to
  1683 ISABELLE_HOME/bin;
  1684 
  1685 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1686 
  1687 * print mode 'emacs' reserved for Isamode;
  1688 
  1689 * support multiple print (ast) translations per constant name;
  1690 
  1691 * theorems involving oracles are now printed with a suffixed [!];
  1692 
  1693 
  1694 *** HOL ***
  1695 
  1696 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1697 
  1698 * HOL/inductive package reorganized and improved: now supports mutual
  1699 definitions such as
  1700 
  1701   inductive EVEN ODD
  1702     intrs
  1703       null "0 : EVEN"
  1704       oddI "n : EVEN ==> Suc n : ODD"
  1705       evenI "n : ODD ==> Suc n : EVEN"
  1706 
  1707 new theorem list "elims" contains an elimination rule for each of the
  1708 recursive sets; inductive definitions now handle disjunctive premises
  1709 correctly (also ZF);
  1710 
  1711 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1712 "mutual_induct" no longer exists - the induction rule is always
  1713 contained in "induct";
  1714 
  1715 
  1716 * HOL/datatype package re-implemented and greatly improved: now
  1717 supports mutually recursive datatypes such as
  1718 
  1719   datatype
  1720     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1721             | SUM ('a aexp) ('a aexp)
  1722             | DIFF ('a aexp) ('a aexp)
  1723             | NUM 'a
  1724   and
  1725     'a bexp = LESS ('a aexp) ('a aexp)
  1726             | AND ('a bexp) ('a bexp)
  1727             | OR ('a bexp) ('a bexp)
  1728 
  1729 as well as indirectly recursive datatypes such as
  1730 
  1731   datatype
  1732     ('a, 'b) term = Var 'a
  1733                   | App 'b ((('a, 'b) term) list)
  1734 
  1735 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1736 induction on mutually / indirectly recursive datatypes.
  1737 
  1738 Primrec equations are now stored in theory and can be accessed via
  1739 <function_name>.simps.
  1740 
  1741 INCOMPATIBILITIES:
  1742 
  1743   - Theories using datatypes must now have theory Datatype as an
  1744     ancestor.
  1745   - The specific <typename>.induct_tac no longer exists - use the
  1746     generic induct_tac instead.
  1747   - natE has been renamed to nat.exhaust - use exhaust_tac
  1748     instead of res_inst_tac ... natE. Note that the variable
  1749     names in nat.exhaust differ from the names in natE, this
  1750     may cause some "fragile" proofs to fail.
  1751   - The theorems split_<typename>_case and split_<typename>_case_asm
  1752     have been renamed to <typename>.split and <typename>.split_asm.
  1753   - Since default sorts of type variables are now handled correctly,
  1754     some datatype definitions may have to be annotated with explicit
  1755     sort constraints.
  1756   - Primrec definitions no longer require function name and type
  1757     of recursive argument.
  1758 
  1759 Consider using isatool fixdatatype to adapt your theories and proof
  1760 scripts to the new package (backup your sources first!).
  1761 
  1762 
  1763 * HOL/record package: considerably improved implementation; now
  1764 includes concrete syntax for record types, terms, updates; theorems
  1765 for surjective pairing and splitting !!-bound record variables; proof
  1766 support is as follows:
  1767 
  1768   1) standard conversions (selectors or updates applied to record
  1769 constructor terms) are part of the standard simpset;
  1770 
  1771   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1772 made part of standard simpset and claset via addIffs;
  1773 
  1774   3) a tactic for record field splitting (record_split_tac) is part of
  1775 the standard claset (addSWrapper);
  1776 
  1777 To get a better idea about these rules you may retrieve them via
  1778 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1779 the name of your record type.
  1780 
  1781 The split tactic 3) conceptually simplifies by the following rule:
  1782 
  1783   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1784 
  1785 Thus any record variable that is bound by meta-all will automatically
  1786 blow up into some record constructor term, consequently the
  1787 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1788 solve record problems automatically.
  1789 
  1790 
  1791 * reorganized the main HOL image: HOL/Integ and String loaded by
  1792 default; theory Main includes everything;
  1793 
  1794 * automatic simplification of integer sums and comparisons, using cancellation;
  1795 
  1796 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1797 
  1798 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1799 
  1800 * many new identities for unions, intersections, set difference, etc.;
  1801 
  1802 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1803 called split_if, split_split, split_sum_case and split_nat_case (to go
  1804 with add/delsplits);
  1805 
  1806 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1807 (?x::unit) = (); this is made part of the default simpset, which COULD
  1808 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1809 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1810 unit_abs_eta_conv is added in order to counter the effect of
  1811 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1812 %u.f();
  1813 
  1814 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1815 makes more sense);
  1816 
  1817 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1818   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1819   disjointness reasoning but breaking a few old proofs.
  1820 
  1821 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1822 to 'converse' from 'inverse' (for compatibility with ZF and some
  1823 literature);
  1824 
  1825 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1826 the well-founded relation;
  1827 
  1828 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1829     Compl A.  The "Compl" syntax remains available as input syntax for this
  1830     release ONLY.
  1831 
  1832 * HOL/Update: new theory of function updates:
  1833     f(a:=b) == %x. if x=a then b else f x
  1834 may also be iterated as in f(a:=b,c:=d,...);
  1835 
  1836 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1837 
  1838 * HOL/List:
  1839   - new function list_update written xs[i:=v] that updates the i-th
  1840     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1841   - new function `upt' written [i..j(] which generates the list
  1842     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1843     bound write [i..j], which is a shorthand for [i..j+1(].
  1844   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1845 
  1846 * HOL/Arith:
  1847   - removed 'pred' (predecessor) function;
  1848   - generalized some theorems about n-1;
  1849   - many new laws about "div" and "mod";
  1850   - new laws about greatest common divisors (see theory ex/Primes);
  1851 
  1852 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1853 instead of "inverse";
  1854 
  1855 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1856   of the multiset ordering;
  1857 
  1858 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1859   (not included by default);
  1860 
  1861 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1862 
  1863 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1864   programs, i.e. different program variables may have different types.
  1865 
  1866 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1867   [previously, this check worked only if the rewrite rule was unconditional]
  1868   Now rew can involve either definitions or equalities (either == or =).
  1869 
  1870 
  1871 *** ZF ***
  1872 
  1873 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1874   only the theorems proved on ZF.ML;
  1875 
  1876 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1877   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1878   disjointness reasoning but breaking a few old proofs.
  1879 
  1880 * ZF/Update: new theory of function updates
  1881     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1882   may also be iterated as in f(a:=b,c:=d,...);
  1883 
  1884 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1885 
  1886 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1887   [previously, this check worked only if the rewrite rule was unconditional]
  1888   Now rew can involve either definitions or equalities (either == or =).
  1889 
  1890 * case_tac provided for compatibility with HOL
  1891     (like the old excluded_middle_tac, but with subgoals swapped)
  1892 
  1893 
  1894 *** Internal programming interfaces ***
  1895 
  1896 * Pure: several new basic modules made available for general use, see
  1897 also src/Pure/README;
  1898 
  1899 * improved the theory data mechanism to support encapsulation (data
  1900 kind name replaced by private Object.kind, acting as authorization
  1901 key); new type-safe user interface via functor TheoryDataFun; generic
  1902 print_data function becomes basically useless;
  1903 
  1904 * removed global_names compatibility flag -- all theory declarations
  1905 are qualified by default;
  1906 
  1907 * module Pure/Syntax now offers quote / antiquote translation
  1908 functions (useful for Hoare logic etc. with implicit dependencies);
  1909 see HOL/ex/Antiquote for an example use;
  1910 
  1911 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1912 cterm -> thm;
  1913 
  1914 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1915 subgoal;
  1916 
  1917 * Display.print_goals function moved to Locale.print_goals;
  1918 
  1919 * standard print function for goals supports current_goals_markers
  1920 variable for marking begin of proof, end of proof, start of goal; the
  1921 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1922 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1923 for example;
  1924 
  1925 
  1926 
  1927 New in Isabelle98 (January 1998)
  1928 --------------------------------
  1929 
  1930 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1931 
  1932 * changed lexical syntax of terms / types: dots made part of long
  1933 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1934 
  1935 * simpset (and claset) reference variable replaced by functions
  1936 simpset / simpset_ref;
  1937 
  1938 * no longer supports theory aliases (via merge) and non-trivial
  1939 implicit merge of thms' signatures;
  1940 
  1941 * most internal names of constants changed due to qualified names;
  1942 
  1943 * changed Pure/Sequence interface (see Pure/seq.ML);
  1944 
  1945 
  1946 *** General Changes ***
  1947 
  1948 * hierachically structured name spaces (for consts, types, axms, thms
  1949 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1950 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1951 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1952 long_names for fully qualified output names; NOTE: ML programs
  1953 (special tactics, packages etc.) referring to internal names may have
  1954 to be adapted to cope with fully qualified names; in case of severe
  1955 backward campatibility problems try setting 'global_names' at compile
  1956 time to have enrything declared within a flat name space; one may also
  1957 fine tune name declarations in theories via the 'global' and 'local'
  1958 section;
  1959 
  1960 * reimplemented the implicit simpset and claset using the new anytype
  1961 data filed in signatures; references simpset:simpset ref etc. are
  1962 replaced by functions simpset:unit->simpset and
  1963 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1964 to patch your ML files accordingly;
  1965 
  1966 * HTML output now includes theory graph data for display with Java
  1967 applet or isatool browser; data generated automatically via isatool
  1968 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1969 
  1970 * defs may now be conditional; improved rewrite_goals_tac to handle
  1971 conditional equations;
  1972 
  1973 * defs now admits additional type arguments, using TYPE('a) syntax;
  1974 
  1975 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1976 creates a new theory node; implicit merge of thms' signatures is
  1977 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1978 transfer:theory->thm->thm in (rare) cases;
  1979 
  1980 * improved handling of draft signatures / theories; draft thms (and
  1981 ctyps, cterms) are automatically promoted to real ones;
  1982 
  1983 * slightly changed interfaces for oracles: admit many per theory, named
  1984 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1985 
  1986 * print_goals: optional output of const types (set show_consts and
  1987 show_types);
  1988 
  1989 * improved output of warnings (###) and errors (***);
  1990 
  1991 * subgoal_tac displays a warning if the new subgoal has type variables;
  1992 
  1993 * removed old README and Makefiles;
  1994 
  1995 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1996 
  1997 * removed obsolete init_pps and init_database;
  1998 
  1999 * deleted the obsolete tactical STATE, which was declared by
  2000     fun STATE tacfun st = tacfun st st;
  2001 
  2002 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2003 (which abbreviates $HOME);
  2004 
  2005 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2006 use isatool fixseq to adapt your ML programs (this works for fully
  2007 qualified references to the Sequence structure only!);
  2008 
  2009 * use_thy no longer requires writable current directory; it always
  2010 reloads .ML *and* .thy file, if either one is out of date;
  2011 
  2012 
  2013 *** Classical Reasoner ***
  2014 
  2015 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2016 tactics that use classical reasoning to simplify a subgoal without
  2017 splitting it into several subgoals;
  2018 
  2019 * Safe_tac: like safe_tac but uses the default claset;
  2020 
  2021 
  2022 *** Simplifier ***
  2023 
  2024 * added simplification meta rules:
  2025     (asm_)(full_)simplify: simpset -> thm -> thm;
  2026 
  2027 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2028 logics (again);
  2029 
  2030 * added prems argument to simplification procedures;
  2031 
  2032 * HOL, FOL, ZF: added infix function `addsplits':
  2033   instead of `<simpset> setloop (split_tac <thms>)'
  2034   you can simply write `<simpset> addsplits <thms>'
  2035 
  2036 
  2037 *** Syntax ***
  2038 
  2039 * TYPE('a) syntax for type reflection terms;
  2040 
  2041 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2042 
  2043 * pretty printer: changed order of mixfix annotation preference (again!);
  2044 
  2045 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2046 
  2047 
  2048 *** HOL ***
  2049 
  2050 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2051   with `addloop' of the simplifier to faciliate case splitting in premises.
  2052 
  2053 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2054 
  2055 * HOL/Auth: new protocol proofs including some for the Internet
  2056   protocol TLS;
  2057 
  2058 * HOL/Map: new theory of `maps' a la VDM;
  2059 
  2060 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2061 cancelling out common nat summands from =, <, <= (in)equalities, or
  2062 differences; simplification procedures nat_cancel_factor for
  2063 cancelling common factor from =, <, <= (in)equalities over natural
  2064 sums; nat_cancel contains both kinds of procedures, it is installed by
  2065 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2066 
  2067 * HOL/simplifier: terms of the form
  2068   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2069   are rewritten to
  2070   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2071   and those of the form
  2072   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2073   are rewritten to
  2074   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2075 
  2076 * HOL/datatype
  2077   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2078 
  2079   P(t_case f1 ... fn x) =
  2080      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2081         ...
  2082        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2083      )
  2084 
  2085   and a theorem `split_t_case_asm' of the form
  2086 
  2087   P(t_case f1 ... fn x) =
  2088     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2089         ...
  2090        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2091      )
  2092   which can be added to a simpset via `addsplits'. The existing theorems
  2093   expand_list_case and expand_option_case have been renamed to
  2094   split_list_case and split_option_case.
  2095 
  2096 * HOL/Arithmetic:
  2097   - `pred n' is automatically converted to `n-1'.
  2098     Users are strongly encouraged not to use `pred' any longer,
  2099     because it will disappear altogether at some point.
  2100   - Users are strongly encouraged to write "0 < n" rather than
  2101     "n ~= 0". Theorems and proof tools have been modified towards this
  2102     `standard'.
  2103 
  2104 * HOL/Lists:
  2105   the function "set_of_list" has been renamed "set" (and its theorems too);
  2106   the function "nth" now takes its arguments in the reverse order and
  2107   has acquired the infix notation "!" as in "xs!n".
  2108 
  2109 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2110 
  2111 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2112   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2113 
  2114 * HOL/record: extensible records with schematic structural subtyping
  2115 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2116 still lacks various theorems and concrete record syntax;
  2117 
  2118 
  2119 *** HOLCF ***
  2120 
  2121 * removed "axioms" and "generated by" sections;
  2122 
  2123 * replaced "ops" section by extended "consts" section, which is capable of
  2124   handling the continuous function space "->" directly;
  2125 
  2126 * domain package:
  2127   . proves theorems immediately and stores them in the theory,
  2128   . creates hierachical name space,
  2129   . now uses normal mixfix annotations (instead of cinfix...),
  2130   . minor changes to some names and values (for consistency),
  2131   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2132   . separator between mutual domain defs: changed "," to "and",
  2133   . improved handling of sort constraints;  now they have to
  2134     appear on the left-hand side of the equations only;
  2135 
  2136 * fixed LAM <x,y,zs>.b syntax;
  2137 
  2138 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2139 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2140 
  2141 
  2142 *** FOL and ZF ***
  2143 
  2144 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2145   with `addloop' of the simplifier to faciliate case splitting in premises.
  2146 
  2147 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2148 in HOL, they strip ALL and --> from proved theorems;
  2149 
  2150 
  2151 
  2152 New in Isabelle94-8 (May 1997)
  2153 ------------------------------
  2154 
  2155 *** General Changes ***
  2156 
  2157 * new utilities to build / run / maintain Isabelle etc. (in parts
  2158 still somewhat experimental); old Makefiles etc. still functional;
  2159 
  2160 * new 'Isabelle System Manual';
  2161 
  2162 * INSTALL text, together with ./configure and ./build scripts;
  2163 
  2164 * reimplemented type inference for greater efficiency, better error
  2165 messages and clean internal interface;
  2166 
  2167 * prlim command for dealing with lots of subgoals (an easier way of
  2168 setting goals_limit);
  2169 
  2170 
  2171 *** Syntax ***
  2172 
  2173 * supports alternative (named) syntax tables (parser and pretty
  2174 printer); internal interface is provided by add_modesyntax(_i);
  2175 
  2176 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2177 be used in conjunction with the Isabelle symbol font; uses the
  2178 "symbols" syntax table;
  2179 
  2180 * added token_translation interface (may translate name tokens in
  2181 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2182 the current print_mode); IMPORTANT: user print translation functions
  2183 are responsible for marking newly introduced bounds
  2184 (Syntax.mark_boundT);
  2185 
  2186 * token translations for modes "xterm" and "xterm_color" that display
  2187 names in bold, underline etc. or colors (which requires a color
  2188 version of xterm);
  2189 
  2190 * infixes may now be declared with names independent of their syntax;
  2191 
  2192 * added typed_print_translation (like print_translation, but may
  2193 access type of constant);
  2194 
  2195 
  2196 *** Classical Reasoner ***
  2197 
  2198 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2199 some limitations.  Blast_tac...
  2200   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2201   + ignores elimination rules that don't have the correct format
  2202         (the conclusion MUST be a formula variable)
  2203   + ignores types, which can make HOL proofs fail
  2204   + rules must not require higher-order unification, e.g. apply_type in ZF
  2205     [message "Function Var's argument not a bound variable" relates to this]
  2206   + its proof strategy is more general but can actually be slower
  2207 
  2208 * substitution with equality assumptions no longer permutes other
  2209 assumptions;
  2210 
  2211 * minor changes in semantics of addafter (now called addaltern); renamed
  2212 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2213 (and access functions for it);
  2214 
  2215 * improved combination of classical reasoner and simplifier:
  2216   + functions for handling clasimpsets
  2217   + improvement of addss: now the simplifier is called _after_ the
  2218     safe steps.
  2219   + safe variant of addss called addSss: uses safe simplifications
  2220     _during_ the safe steps. It is more complete as it allows multiple
  2221     instantiations of unknowns (e.g. with slow_tac).
  2222 
  2223 *** Simplifier ***
  2224 
  2225 * added interface for simplification procedures (functions that
  2226 produce *proven* rewrite rules on the fly, depending on current
  2227 redex);
  2228 
  2229 * ordering on terms as parameter (used for ordered rewriting);
  2230 
  2231 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2232 
  2233 * the solver is now split into a safe and an unsafe part.
  2234 This should be invisible for the normal user, except that the
  2235 functions setsolver and addsolver have been renamed to setSolver and
  2236 addSolver; added safe_asm_full_simp_tac;
  2237 
  2238 
  2239 *** HOL ***
  2240 
  2241 * a generic induction tactic `induct_tac' which works for all datatypes and
  2242 also for type `nat';
  2243 
  2244 * a generic case distinction tactic `exhaust_tac' which works for all
  2245 datatypes and also for type `nat';
  2246 
  2247 * each datatype comes with a function `size';
  2248 
  2249 * patterns in case expressions allow tuple patterns as arguments to
  2250 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2251 
  2252 * primrec now also works with type nat;
  2253 
  2254 * recdef: a new declaration form, allows general recursive functions to be
  2255 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2256 
  2257 * the constant for negation has been renamed from "not" to "Not" to
  2258 harmonize with FOL, ZF, LK, etc.;
  2259 
  2260 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2261 infinite lists;
  2262 
  2263 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2264 
  2265 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2266 problems in commutative rings, using axiomatic type classes for + and *;
  2267 
  2268 * more examples in HOL/MiniML and HOL/Auth;
  2269 
  2270 * more default rewrite rules for quantifiers, union/intersection;
  2271 
  2272 * a new constant `arbitrary == @x.False';
  2273 
  2274 * HOLCF/IOA replaces old HOL/IOA;
  2275 
  2276 * HOLCF changes: derived all rules and arities
  2277   + axiomatic type classes instead of classes
  2278   + typedef instead of faking type definitions
  2279   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2280   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2281   + eliminated the types void, one, tr
  2282   + use unit lift and bool lift (with translations) instead of one and tr
  2283   + eliminated blift from Lift3.thy (use Def instead of blift)
  2284   all eliminated rules are derived as theorems --> no visible changes ;
  2285 
  2286 
  2287 *** ZF ***
  2288 
  2289 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2290 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2291 as ZF_cs addSIs [equalityI];
  2292 
  2293 
  2294 
  2295 New in Isabelle94-7 (November 96)
  2296 ---------------------------------
  2297 
  2298 * allowing negative levels (as offsets) in prlev and choplev;
  2299 
  2300 * super-linear speedup for large simplifications;
  2301 
  2302 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2303 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2304 FAIL); can suppress it using the command Delsimps (ex_simps @
  2305 all_simps); De Morgan laws are also now included, by default;
  2306 
  2307 * improved printing of ==>  :  ~:
  2308 
  2309 * new object-logic "Sequents" adds linear logic, while replacing LK
  2310 and Modal (thanks to Sara Kalvala);
  2311 
  2312 * HOL/Auth: correctness proofs for authentication protocols;
  2313 
  2314 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2315 examples on HOL/Auth);
  2316 
  2317 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2318 the rewriter and classical reasoner simultaneously;
  2319 
  2320 * function uresult no longer returns theorems in "standard" format;
  2321 regain previous version by: val uresult = standard o uresult;
  2322 
  2323 
  2324 
  2325 New in Isabelle94-6
  2326 -------------------
  2327 
  2328 * oracles -- these establish an interface between Isabelle and trusted
  2329 external reasoners, which may deliver results as theorems;
  2330 
  2331 * proof objects (in particular record all uses of oracles);
  2332 
  2333 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2334 
  2335 * "constdefs" section in theory files;
  2336 
  2337 * "primrec" section (HOL) no longer requires names;
  2338 
  2339 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2340 
  2341 
  2342 
  2343 New in Isabelle94-5
  2344 -------------------
  2345 
  2346 * reduced space requirements;
  2347 
  2348 * automatic HTML generation from theories;
  2349 
  2350 * theory files no longer require "..." (quotes) around most types;
  2351 
  2352 * new examples, including two proofs of the Church-Rosser theorem;
  2353 
  2354 * non-curried (1994) version of HOL is no longer distributed;
  2355 
  2356 
  2357 
  2358 New in Isabelle94-4
  2359 -------------------
  2360 
  2361 * greatly reduced space requirements;
  2362 
  2363 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2364 
  2365 * searchable theorem database (see the section "Retrieving theorems" on
  2366 page 8 of the Reference Manual);
  2367 
  2368 * new examples, including Grabczewski's monumental case study of the
  2369 Axiom of Choice;
  2370 
  2371 * The previous version of HOL renamed to Old_HOL;
  2372 
  2373 * The new version of HOL (previously called CHOL) uses a curried syntax
  2374 for functions.  Application looks like f a b instead of f(a,b);
  2375 
  2376 * Mutually recursive inductive definitions finally work in HOL;
  2377 
  2378 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2379 translates to the operator "split";
  2380 
  2381 
  2382 
  2383 New in Isabelle94-3
  2384 -------------------
  2385 
  2386 * new infix operator, addss, allowing the classical reasoner to
  2387 perform simplification at each step of its search.  Example:
  2388         fast_tac (cs addss ss)
  2389 
  2390 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2391 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2392 look like (a,b) instead of <a,b>;
  2393 
  2394 * PLEASE NOTE: CHOL will eventually replace HOL!
  2395 
  2396 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2397 It translates to the operator "split".  A new theory of integers is available;
  2398 
  2399 * In ZF, integer numerals now denote two's-complement binary integers.
  2400 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2401 
  2402 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2403 of the Axiom of Choice;
  2404 
  2405 
  2406 
  2407 New in Isabelle94-2
  2408 -------------------
  2409 
  2410 * Significantly faster resolution;
  2411 
  2412 * the different sections in a .thy file can now be mixed and repeated
  2413 freely;
  2414 
  2415 * Database of theorems for FOL, HOL and ZF.  New
  2416 commands including qed, qed_goal and bind_thm store theorems in the database.
  2417 
  2418 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2419 a given theory (thms_of), or find out what theory a theorem was proved in
  2420 (theory_of_thm);
  2421 
  2422 * Bugs fixed in the inductive definition and datatype packages;
  2423 
  2424 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2425 and HOL_dup_cs obsolete;
  2426 
  2427 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2428 have been removed;
  2429 
  2430 * Simpler definition of function space in ZF;
  2431 
  2432 * new results about cardinal and ordinal arithmetic in ZF;
  2433 
  2434 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2435 types;
  2436 
  2437 
  2438 $Id$