NEWS
author kleing
Mon May 05 13:52:19 2003 +0200 (2003-05-05)
changeset 13954 2e989faba65a
parent 13953 65b76920e108
child 13960 70f9158b6695
permissions -rw-r--r--
fixed \<0>..\<9> (-> \<zero>..\<nine>)
     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: The main goal of the proof state is no longer shown by default, only
    53 the subgoals. This behaviour is controlled by a new flag.
    54    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
    55 (ML: Proof.show_main_goal).
    56 
    57 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
    58 rules whose conclusion matches subgoal 1:
    59       PG menu: Isabelle/Isar -> Show me -> matching rules
    60 The rules are ordered by how closely they match the subgoal.
    61 In particular, rules that solve a subgoal outright are displayed first
    62 (or rather last, the way they are printed).
    63 (ML: ProofGeneral.print_intros())
    64 
    65 * Pure: New flag trace_unify_fail causes unification to print
    66 diagnostic information (PG: in trace buffer) when it fails. This is
    67 useful for figuring out why single step proofs like rule, erule or
    68 assumption failed.
    69 
    70 * Pure: Locale specifications now produce predicate definitions
    71 according to the body of text (covering assumptions modulo local
    72 definitions); predicate "loc_axioms" covers newly introduced text,
    73 while "loc" is cumulative wrt. all included locale expressions; the
    74 latter view is presented only on export into the global theory
    75 context; potential INCOMPATIBILITY, use "(open)" option to fall back
    76 on the old view without predicates;
    77 
    78 * Pure: predefined locales "var" and "struct" are useful for sharing
    79 parameters (as in CASL, for example); just specify something like
    80 ``var x + var y + struct M'' as import;
    81 
    82 * Pure: improved thms_containing: proper indexing of facts instead of
    83 raw theorems; check validity of results wrt. current name space;
    84 include local facts of proof configuration (also covers active
    85 locales), cover fixed variables in index; may use "_" in term
    86 specification; an optional limit for the number of printed facts may
    87 be given (the default is 40);
    88 
    89 * Pure: disallow duplicate fact bindings within new-style theory files
    90 (batch-mode only);
    91 
    92 * Provers: improved induct method: assumptions introduced by case
    93 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
    94 the goal statement); "foo" still refers to all facts collectively;
    95 
    96 * Provers: the function blast.overloaded has been removed: all constants
    97 are regarded as potentially overloaded, which improves robustness in exchange
    98 for slight decrease in efficiency;
    99 
   100 * Provers/linorder: New generic prover for transitivity reasoning over
   101 linear orders.  Note: this prover is not efficient!
   102 
   103 * Isar: preview of problems to finish 'show' now produce an error
   104 rather than just a warning (in interactive mode);
   105 
   106 
   107 *** HOL ***
   108 
   109 * arith(_tac)
   110 
   111  - Produces a counter example if it cannot prove a goal.
   112    Note that the counter example may be spurious if the goal is not a formula
   113    of quantifier-free linear arithmetic.
   114    In ProofGeneral the counter example appears in the trace buffer.
   115 
   116  - Knows about div k and mod k where k is a numeral of type nat or int.
   117 
   118  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   119    linear arithmetic fails. This takes account of quantifiers and divisibility.
   120    Presburger arithmetic can also be called explicitly via presburger(_tac). 
   121 
   122 * simp's arithmetic capabilities have been enhanced a bit: it now
   123 takes ~= in premises into account (by performing a case split);
   124 
   125 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   126 are distributed over a sum of terms;
   127 
   128 * New tactic "trans_tac" and method "trans" instantiate
   129 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   130 "<=", "<" and "="). 
   131 
   132 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main 
   133 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   134 
   135 * 'typedef' command has new option "open" to suppress the set
   136 definition;
   137 
   138 * functions Min and Max on finite sets have been introduced (theory
   139 Finite_Set);
   140 
   141 * attribute [symmetric] now works for relations as well; it turns
   142 (x,y) : R^-1 into (y,x) : R, and vice versa;
   143 
   144 * induct over a !!-quantified statement (say !!x1..xn):
   145   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   146 
   147 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   148 %x. None. Warning: empty_def now refers to the previously hidden definition
   149 of the empty set.
   150 
   151 * Real/HahnBanach: updated and adapted to locales;
   152 
   153 * GroupTheory: converted to Isar theories, using locales with implicit
   154 structures.  Also a new, experimental summation operator for abelian groups;
   155 
   156 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad, Gray and
   157 Kramer);
   158 
   159 * UNITY: added the Meier-Sanders theory of progress sets;
   160 
   161 
   162 *** ZF ***
   163 
   164 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   165 universe, etc.);
   166 
   167 * Main ZF: virtually all theories converted to new-style format;
   168 
   169 
   170 *** ML ***
   171 
   172 * Pure: Tactic.prove provides sane interface for internal proofs;
   173 omits the infamous "standard" operation, so this is more appropriate
   174 than prove_goalw_cterm in many situations (e.g. in simprocs);
   175 
   176 * Pure: improved error reporting of simprocs;
   177 
   178 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   179 up simprocs;
   180 
   181 
   182 *** Document preparation ***
   183 
   184 * uses \par instead of \\ for line breaks in theory text. This may
   185 shift some page breaks in large documents. To get the old behaviour
   186 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   187 
   188 * minimized dependencies of isabelle.sty and isabellesym.sty on 
   189 other packages
   190 
   191 * \<euro> now needs package babel/greek instead of marvosym (which
   192 broke \Rightarrow)
   193 
   194 * normal size for \<zero>...\<nine> (uses \mathbf instead of 
   195 textcomp package)
   196 
   197 
   198 New in Isabelle2002 (March 2002)
   199 --------------------------------
   200 
   201 *** Document preparation ***
   202 
   203 * greatly simplified document preparation setup, including more
   204 graceful interpretation of isatool usedir -i/-d/-D options, and more
   205 instructive isatool mkdir; users should basically be able to get
   206 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   207 users may run a separate document processing stage manually like this:
   208 "isatool usedir -D output HOL Test && isatool document Test/output";
   209 
   210 * theory dependency graph may now be incorporated into documents;
   211 isatool usedir -g true will produce session_graph.eps/.pdf for use
   212 with \includegraphics of LaTeX;
   213 
   214 * proper spacing of consecutive markup elements, especially text
   215 blocks after section headings;
   216 
   217 * support bold style (for single symbols only), input syntax is like
   218 this: "\<^bold>\<alpha>" or "\<^bold>A";
   219 
   220 * \<bullet> is now output as bold \cdot by default, which looks much
   221 better in printed text;
   222 
   223 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   224 note that these symbols are currently unavailable in Proof General /
   225 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   226 
   227 * isatool latex no longer depends on changed TEXINPUTS, instead
   228 isatool document copies the Isabelle style files to the target
   229 location;
   230 
   231 
   232 *** Isar ***
   233 
   234 * Pure/Provers: improved proof by cases and induction;
   235   - 'case' command admits impromptu naming of parameters (such as
   236     "case (Suc n)");
   237   - 'induct' method divinates rule instantiation from the inductive
   238     claim; no longer requires excessive ?P bindings for proper
   239     instantiation of cases;
   240   - 'induct' method properly enumerates all possibilities of set/type
   241     rules; as a consequence facts may be also passed through *type*
   242     rules without further ado;
   243   - 'induct' method now derives symbolic cases from the *rulified*
   244     rule (before it used to rulify cases stemming from the internal
   245     atomized version); this means that the context of a non-atomic
   246     statement becomes is included in the hypothesis, avoiding the
   247     slightly cumbersome show "PROP ?case" form;
   248   - 'induct' may now use elim-style induction rules without chaining
   249     facts, using ``missing'' premises from the goal state; this allows
   250     rules stemming from inductive sets to be applied in unstructured
   251     scripts, while still benefitting from proper handling of non-atomic
   252     statements; NB: major inductive premises need to be put first, all
   253     the rest of the goal is passed through the induction;
   254   - 'induct' proper support for mutual induction involving non-atomic
   255     rule statements (uses the new concept of simultaneous goals, see
   256     below);
   257   - append all possible rule selections, but only use the first
   258     success (no backtracking);
   259   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   260   - undeclared rule case names default to numbers 1, 2, 3, ...;
   261   - added 'print_induct_rules' (covered by help item in recent Proof
   262     General versions);
   263   - moved induct/cases attributes to Pure, methods to Provers;
   264   - generic method setup instantiated for FOL and HOL;
   265 
   266 * Pure: support multiple simultaneous goal statements, for example
   267 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   268 meta-level mechanism, this acts as if several individual goals had
   269 been stated separately; in particular common proof methods need to be
   270 repeated in order to cover all claims; note that a single elimination
   271 step is *not* sufficient to establish the two conjunctions, so this
   272 fails:
   273 
   274   assume "A & B" then have A and B ..   (*".." fails*)
   275 
   276 better use "obtain" in situations as above; alternative refer to
   277 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   278 
   279 * Pure: proper integration with ``locales''; unlike the original
   280 version by Florian Kammüller, Isar locales package high-level proof
   281 contexts rather than raw logical ones (e.g. we admit to include
   282 attributes everywhere); operations on locales include merge and
   283 rename; support for implicit arguments (``structures''); simultaneous
   284 type-inference over imports and text; see also HOL/ex/Locales.thy for
   285 some examples;
   286 
   287 * Pure: the following commands have been ``localized'', supporting a
   288 target locale specification "(in name)": 'lemma', 'theorem',
   289 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   290 stored both within the locale and at the theory level (exported and
   291 qualified by the locale name);
   292 
   293 * Pure: theory goals may now be specified in ``long'' form, with
   294 ad-hoc contexts consisting of arbitrary locale elements. for example
   295 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   296 definitions may be given, too); the result is a meta-level rule with
   297 the context elements being discharged in the obvious way;
   298 
   299 * Pure: new proof command 'using' allows to augment currently used
   300 facts after a goal statement ('using' is syntactically analogous to
   301 'apply', but acts on the goal's facts only); this allows chained facts
   302 to be separated into parts given before and after a claim, as in
   303 ``from a and b have C using d and e <proof>'';
   304 
   305 * Pure: renamed "antecedent" case to "rule_context";
   306 
   307 * Pure: new 'judgment' command records explicit information about the
   308 object-logic embedding (used by several tools internally); no longer
   309 use hard-wired "Trueprop";
   310 
   311 * Pure: added 'corollary' command;
   312 
   313 * Pure: fixed 'token_translation' command;
   314 
   315 * Pure: removed obsolete 'exported' attribute;
   316 
   317 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   318 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   319 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   320 
   321 * Pure: method 'atomize' presents local goal premises as object-level
   322 statements (atomic meta-level propositions); setup controlled via
   323 rewrite rules declarations of 'atomize' attribute; example
   324 application: 'induct' method with proper rule statements in improper
   325 proof *scripts*;
   326 
   327 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   328 now consider the syntactic context of assumptions, giving a better
   329 chance to get type-inference of the arguments right (this is
   330 especially important for locales);
   331 
   332 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   333 mode;
   334 
   335 * Pure/obtain: the formal conclusion "thesis", being marked as
   336 ``internal'', may no longer be reference directly in the text;
   337 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   338 situations;
   339 
   340 * Pure: generic 'sym' attribute which declares a rule both as pure
   341 'elim?' and for the 'symmetric' operation;
   342 
   343 * Pure: marginal comments ``--'' may now occur just anywhere in the
   344 text; the fixed correlation with particular command syntax has been
   345 discontinued;
   346 
   347 * Pure: new method 'rules' is particularly well-suited for proof
   348 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   349 but often produces more compact proof terms with less detours;
   350 
   351 * Pure/Provers/classical: simplified integration with pure rule
   352 attributes and methods; the classical "intro?/elim?/dest?"
   353 declarations coincide with the pure ones; the "rule" method no longer
   354 includes classically swapped intros; "intro" and "elim" methods no
   355 longer pick rules from the context; also got rid of ML declarations
   356 AddXIs/AddXEs/AddXDs; all of this has some potential for
   357 INCOMPATIBILITY;
   358 
   359 * Provers/classical: attribute 'swapped' produces classical inversions
   360 of introduction rules;
   361 
   362 * Provers/simplifier: 'simplified' attribute may refer to explicit
   363 rules instead of full simplifier context; 'iff' attribute handles
   364 conditional rules;
   365 
   366 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   367 
   368 * HOL: 'recdef' now fails on unfinished automated proofs, use
   369 "(permissive)" option to recover old behavior;
   370 
   371 * HOL: 'inductive' no longer features separate (collective) attributes
   372 for 'intros' (was found too confusing);
   373 
   374 * HOL: properly declared induction rules less_induct and
   375 wf_induct_rule;
   376 
   377 
   378 *** HOL ***
   379 
   380 * HOL: moved over to sane numeral syntax; the new policy is as
   381 follows:
   382 
   383   - 0 and 1 are polymorphic constants, which are defined on any
   384   numeric type (nat, int, real etc.);
   385 
   386   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   387   binary representation internally;
   388 
   389   - type nat has special constructor Suc, and generally prefers Suc 0
   390   over 1::nat and Suc (Suc 0) over 2::nat;
   391 
   392 This change may cause significant problems of INCOMPATIBILITY; here
   393 are some hints on converting existing sources:
   394 
   395   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   396   entities, so expressions involving "-" (unary or binary minus) need
   397   to be spaced properly;
   398 
   399   - existing occurrences of "1" may need to be constraint "1::nat" or
   400   even replaced by Suc 0; similar for old "2";
   401 
   402   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   403 
   404   - remove all special provisions on numerals in proofs;
   405 
   406 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   407 representation (depends on bin_arith_simps in the default context);
   408 
   409 * HOL: symbolic syntax for x^2 (numeral 2);
   410 
   411 * HOL: the class of all HOL types is now called "type" rather than
   412 "term"; INCOMPATIBILITY, need to adapt references to this type class
   413 in axclass/classes, instance/arities, and (usually rare) occurrences
   414 in typings (of consts etc.); internally the class is called
   415 "HOL.type", ML programs should refer to HOLogic.typeS;
   416 
   417 * HOL/record package improvements:
   418   - new derived operations "fields" to build a partial record section,
   419     "extend" to promote a fixed record to a record scheme, and
   420     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   421     declared as simp by default;
   422   - shared operations ("more", "fields", etc.) now need to be always
   423     qualified) --- potential INCOMPATIBILITY;
   424   - removed "make_scheme" operations (use "make" with "extend") --
   425     INCOMPATIBILITY;
   426   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   427   - provides cases/induct rules for use with corresponding Isar
   428     methods (for concrete records, record schemes, concrete more
   429     parts, and schematic more parts -- in that order);
   430   - internal definitions directly based on a light-weight abstract
   431     theory of product types over typedef rather than datatype;
   432 
   433 * HOL: generic code generator for generating executable ML code from
   434 specifications; specific support for HOL constructs such as inductive
   435 datatypes and sets, as well as recursive functions; can be invoked
   436 via 'generate_code' theory section;
   437 
   438 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   439 
   440 * HOL: consolidated and renamed several theories.  In particular:
   441 	Ord.thy has been absorbed into HOL.thy
   442 	String.thy has been absorbed into List.thy
   443  
   444 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   445 (beware of argument permutation!);
   446 
   447 * HOL: linorder_less_split superseded by linorder_cases;
   448 
   449 * HOL/List: "nodups" renamed to "distinct";
   450 
   451 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   452 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   453   - Ex_def has changed, now need to use some_eq_ex
   454 
   455 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   456 in this (rare) case use:
   457 
   458   delSWrapper "split_all_tac"
   459   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   460 
   461 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   462 MAY FAIL;
   463 
   464 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   465 Isabelle's type classes, ^ on functions and relations has too general
   466 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   467 necessary to attach explicit type constraints;
   468 
   469 * HOL/Relation: the prefix name of the infix "O" has been changed from
   470 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   471 renamed accordingly (eg "compI" -> "rel_compI").
   472 
   473 * HOL: syntax translations now work properly with numerals and records
   474 expressions;
   475 
   476 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   477 of "lam" -- INCOMPATIBILITY;
   478 
   479 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   480 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   481 renamed "Product_Type.unit";
   482 
   483 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   484 
   485 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   486 the "cases" method);
   487 
   488 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   489 Florian Kammüller);
   490 
   491 * HOL/IMP: updated and converted to new-style theory format; several
   492 parts turned into readable document, with proper Isar proof texts and
   493 some explanations (by Gerwin Klein);
   494 
   495 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   496 
   497 * HOL-Hyperreal is now a logic image;
   498 
   499 
   500 *** HOLCF ***
   501 
   502 * Isar: consts/constdefs supports mixfix syntax for continuous
   503 operations;
   504 
   505 * Isar: domain package adapted to new-style theory format, e.g. see
   506 HOLCF/ex/Dnat.thy;
   507 
   508 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   509 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   510 lift.induct_tac, always use UU instead of Undef;
   511 
   512 * HOLCF/IMP: updated and converted to new-style theory;
   513 
   514 
   515 *** ZF ***
   516 
   517 * Isar: proper integration of logic-specific tools and packages,
   518 including theory commands '(co)inductive', '(co)datatype',
   519 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   520 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   521 
   522 * theory Main no longer includes AC; for the Axiom of Choice, base
   523 your theory on Main_ZFC;
   524 
   525 * the integer library now covers quotients and remainders, with many
   526 laws relating division to addition, multiplication, etc.;
   527 
   528 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   529 typeless version of the formalism;
   530 
   531 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   532 format;
   533 
   534 * ZF/Induct: new directory for examples of inductive definitions,
   535 including theory Multiset for multiset orderings; converted to
   536 new-style theory format;
   537 
   538 * ZF: many new theorems about lists, ordinals, etc.;
   539 
   540 
   541 *** General ***
   542 
   543 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   544 variable proof controls level of detail: 0 = no proofs (only oracle
   545 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   546 also ref manual for further ML interfaces;
   547 
   548 * Pure/axclass: removed obsolete ML interface
   549 goal_subclass/goal_arity;
   550 
   551 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   552 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   553 separate tokens, so expressions involving minus need to be spaced
   554 properly;
   555 
   556 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   557 rather than "infixl" or "infixr";
   558 
   559 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   560 sort constraint specifications in type inference; e.g. "x::_::foo"
   561 ensures that the type of "x" is of sort "foo" (but not necessarily a
   562 type variable);
   563 
   564 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   565 control output of nested => (types); the default behavior is
   566 "type_brackets";
   567 
   568 * Pure/syntax: builtin parse translation for "_constify" turns valued
   569 tokens into AST constants;
   570 
   571 * Pure/syntax: prefer later declarations of translations and print
   572 translation functions; potential INCOMPATIBILITY: need to reverse
   573 multiple declarations for same syntax element constant;
   574 
   575 * Pure/show_hyps reset by default (in accordance to existing Isar
   576 practice);
   577 
   578 * Provers/classical: renamed addaltern to addafter, addSaltern to
   579 addSafter;
   580 
   581 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   582 as well;
   583 
   584 * system: tested support for MacOS X; should be able to get Isabelle +
   585 Proof General to work in a plain Terminal after installing Poly/ML
   586 (e.g. from the Isabelle distribution area) and GNU bash alone
   587 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   588 support requires further installations, e.g. from
   589 http://fink.sourceforge.net/);
   590 
   591 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   592 
   593 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   594 of 40 MB), cf. ML_OPTIONS;
   595 
   596 * system: Proof General keywords specification is now part of the
   597 Isabelle distribution (see etc/isar-keywords.el);
   598 
   599 * system: support for persistent Proof General sessions (refrain from
   600 outdating all loaded theories on startup); user may create writable
   601 logic images like this: ``isabelle -q HOL Test'';
   602 
   603 * system: smart selection of Isabelle process versus Isabelle
   604 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   605 run both "isabelle" and "Isabelle" even if file names are badly
   606 damaged (executable inspects the case of the first letter of its own
   607 name); added separate "isabelle-process" and "isabelle-interface";
   608 
   609 * system: refrain from any attempt at filtering input streams; no
   610 longer support ``8bit'' encoding of old isabelle font, instead proper
   611 iso-latin characters may now be used; the related isatools
   612 "symbolinput" and "nonascii" have disappeared as well;
   613 
   614 * system: removed old "xterm" interface (the print modes "xterm" and
   615 "xterm_color" are still available for direct use in a suitable
   616 terminal);
   617 
   618 
   619 
   620 New in Isabelle99-2 (February 2001)
   621 -----------------------------------
   622 
   623 *** Overview of INCOMPATIBILITIES ***
   624 
   625 * HOL: please note that theories in the Library and elsewhere often use the
   626 new-style (Isar) format; to refer to their theorems in an ML script you must
   627 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   628 
   629 * HOL: inductive package no longer splits induction rule aggressively,
   630 but only as far as specified by the introductions given; the old
   631 format may be recovered via ML function complete_split_rule or attribute
   632 'split_rule (complete)';
   633 
   634 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   635 gfp_Tarski to gfp_unfold;
   636 
   637 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   638 
   639 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   640 relation); infix "^^" has been renamed "``"; infix "``" has been
   641 renamed "`"; "univalent" has been renamed "single_valued";
   642 
   643 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   644 operation;
   645 
   646 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   647 
   648 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   649 
   650 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   651 consequence, it is no longer monotonic wrt. the local goal context
   652 (which is now passed through the inductive cases);
   653 
   654 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   655 \<gg> to \<ggreater>;
   656 
   657 
   658 *** Document preparation ***
   659 
   660 * \isabellestyle{NAME} selects version of Isabelle output (currently
   661 available: are "it" for near math-mode best-style output, "sl" for
   662 slanted text style, and "tt" for plain type-writer; if no
   663 \isabellestyle command is given, output is according to slanted
   664 type-writer);
   665 
   666 * support sub/super scripts (for single symbols only), input syntax is
   667 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   668 
   669 * some more standard symbols; see Appendix A of the system manual for
   670 the complete list of symbols defined in isabellesym.sty;
   671 
   672 * improved isabelle style files; more abstract symbol implementation
   673 (should now use \isamath{...} and \isatext{...} in custom symbol
   674 definitions);
   675 
   676 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   677 state; Note that presentation of goal states does not conform to
   678 actual human-readable proof documents.  Please do not include goal
   679 states into document output unless you really know what you are doing!
   680 
   681 * proper indentation of antiquoted output with proportional LaTeX
   682 fonts;
   683 
   684 * no_document ML operator temporarily disables LaTeX document
   685 generation;
   686 
   687 * isatool unsymbolize tunes sources for plain ASCII communication;
   688 
   689 
   690 *** Isar ***
   691 
   692 * Pure: Isar now suffers initial goal statements to contain unbound
   693 schematic variables (this does not conform to actual readable proof
   694 documents, due to unpredictable outcome and non-compositional proof
   695 checking); users who know what they are doing may use schematic goals
   696 for Prolog-style synthesis of proven results;
   697 
   698 * Pure: assumption method (an implicit finishing) now handles actual
   699 rules as well;
   700 
   701 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   702 initial goal, declare "that" only as Pure intro (only for single
   703 steps); the "that" rule assumption may now be involved in implicit
   704 finishing, thus ".." becomes a feasible for trivial obtains;
   705 
   706 * Pure: default proof step now includes 'intro_classes'; thus trivial
   707 instance proofs may be performed by "..";
   708 
   709 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   710 statements as well;
   711 
   712 * Pure: more robust selection of calculational rules;
   713 
   714 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   715 rule (as well as the assumption rule);
   716 
   717 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   718 lemmas, using the graph browser tool;
   719 
   720 * Pure: predict failure of "show" in interactive mode;
   721 
   722 * Pure: 'thms_containing' now takes actual terms as arguments;
   723 
   724 * HOL: improved method 'induct' --- now handles non-atomic goals
   725 (potential INCOMPATIBILITY); tuned error handling;
   726 
   727 * HOL: cases and induct rules now provide explicit hints about the
   728 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   729 any remaining facts are inserted into the goal verbatim;
   730 
   731 * HOL: local contexts (aka cases) may now contain term bindings as
   732 well; the 'cases' and 'induct' methods new provide a ?case binding for
   733 the result to be shown in each case;
   734 
   735 * HOL: added 'recdef_tc' command;
   736 
   737 * isatool convert assists in eliminating legacy ML scripts;
   738 
   739 
   740 *** HOL ***
   741 
   742 * HOL/Library: a collection of generic theories to be used together
   743 with main HOL; the theory loader path already includes this directory
   744 by default; the following existing theories have been moved here:
   745 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   746 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   747 
   748 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   749 modelling and verification task performed in Isabelle/HOL +
   750 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   751 
   752 * HOL/Algebra: special summation operator SUM no longer exists, it has
   753 been replaced by setsum; infix 'assoc' now has priority 50 (like
   754 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   755 'domain', this makes the theory consistent with mathematical
   756 literature;
   757 
   758 * HOL basics: added overloaded operations "inverse" and "divide"
   759 (infix "/"), syntax for generic "abs" operation, generic summation
   760 operator \<Sum>;
   761 
   762 * HOL/typedef: simplified package, provide more useful rules (see also
   763 HOL/subset.thy);
   764 
   765 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   766 now expressed as a proper nested rule (old-style tactic scripts may
   767 require atomize_strip_tac to cope with non-atomic premises);
   768 
   769 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   770 to "split_conv" (old name still available for compatibility);
   771 
   772 * HOL: improved concrete syntax for strings (e.g. allows translation
   773 rules with string literals);
   774 
   775 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   776  and Fleuriot's mechanization of analysis, including the transcendental
   777  functions for the reals;
   778 
   779 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   780 
   781 
   782 *** CTT ***
   783 
   784 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   785 "lam" is displayed as TWO lambda-symbols
   786 
   787 * CTT: theory Main now available, containing everything (that is, Bool
   788 and Arith);
   789 
   790 
   791 *** General ***
   792 
   793 * Pure: the Simplifier has been implemented properly as a derived rule
   794 outside of the actual kernel (at last!); the overall performance
   795 penalty in practical applications is about 50%, while reliability of
   796 the Isabelle inference kernel has been greatly improved;
   797 
   798 * print modes "brackets" and "no_brackets" control output of nested =>
   799 (types) and ==> (props); the default behaviour is "brackets";
   800 
   801 * Provers: fast_tac (and friends) now handle actual object-logic rules
   802 as assumptions as well;
   803 
   804 * system: support Poly/ML 4.0;
   805 
   806 * system: isatool install handles KDE version 1 or 2;
   807 
   808 
   809 
   810 New in Isabelle99-1 (October 2000)
   811 ----------------------------------
   812 
   813 *** Overview of INCOMPATIBILITIES ***
   814 
   815 * HOL: simplification of natural numbers is much changed; to partly
   816 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   817 issue the following ML commands:
   818 
   819   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   820   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   821 
   822 * HOL: simplification no longer dives into case-expressions; this is
   823 controlled by "t.weak_case_cong" for each datatype t;
   824 
   825 * HOL: nat_less_induct renamed to less_induct;
   826 
   827 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   828 fixsome to patch .thy and .ML sources automatically;
   829 
   830   select_equality  -> some_equality
   831   select_eq_Ex     -> some_eq_ex
   832   selectI2EX       -> someI2_ex
   833   selectI2         -> someI2
   834   selectI          -> someI
   835   select1_equality -> some1_equality
   836   Eps_sym_eq       -> some_sym_eq_trivial
   837   Eps_eq           -> some_eq_trivial
   838 
   839 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   840 
   841 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   842 instead);
   843 
   844 * HOL: the recursion equations generated by 'recdef' are now called
   845 f.simps instead of f.rules;
   846 
   847 * HOL: qed_spec_mp now also handles bounded ALL as well;
   848 
   849 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   850 sometimes be needed;
   851 
   852 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   853 
   854 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   855 
   856 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   857 product is now "<*>" instead of "Times"; the lexicographic product is
   858 now "<*lex*>" instead of "**";
   859 
   860 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   861 of main HOL, but was unused); better use HOL's datatype package;
   862 
   863 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   864 the old syntax may be recovered as follows:
   865 
   866   syntax (symbols)
   867     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   868       (infixl "\\<oplus>" 100)
   869 
   870 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   871 
   872 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   873 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   874 internally;
   875 
   876 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   877 changed from A/r to A//r;
   878 
   879 * ZF: new treatment of arithmetic (nat & int) may break some old
   880 proofs;
   881 
   882 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   883 rulify -> rule_format, elimify -> elim_format, ...);
   884 
   885 * Isar/Provers: intro/elim/dest attributes changed; renamed
   886 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   887 should have to change intro!! to intro? only); replaced "delrule" by
   888 "rule del";
   889 
   890 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   891 
   892 * Provers: strengthened force_tac by using new first_best_tac;
   893 
   894 * LaTeX document preparation: several changes of isabelle.sty (see
   895 lib/texinputs);
   896 
   897 
   898 *** Document preparation ***
   899 
   900 * formal comments (text blocks etc.) in new-style theories may now
   901 contain antiquotations of thm/prop/term/typ/text to be presented
   902 according to latex print mode; concrete syntax is like this:
   903 @{term[show_types] "f(x) = a + x"};
   904 
   905 * isatool mkdir provides easy setup of Isabelle session directories,
   906 including proper document sources;
   907 
   908 * generated LaTeX sources are now deleted after successful run
   909 (isatool document -c); may retain a copy somewhere else via -D option
   910 of isatool usedir;
   911 
   912 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   913 style files, achieving self-contained LaTeX sources and simplifying
   914 LaTeX debugging;
   915 
   916 * old-style theories now produce (crude) LaTeX output as well;
   917 
   918 * browser info session directories are now self-contained (may be put
   919 on WWW server seperately); improved graphs of nested sessions; removed
   920 graph for 'all sessions';
   921 
   922 * several improvements in isabelle style files; \isabellestyle{it}
   923 produces fake math mode output; \isamarkupheader is now \section by
   924 default; see lib/texinputs/isabelle.sty etc.;
   925 
   926 
   927 *** Isar ***
   928 
   929 * Isar/Pure: local results and corresponding term bindings are now
   930 subject to Hindley-Milner polymorphism (similar to ML); this
   931 accommodates incremental type-inference very nicely;
   932 
   933 * Isar/Pure: new derived language element 'obtain' supports
   934 generalized existence reasoning;
   935 
   936 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   937 support accumulation of results, without applying any rules yet;
   938 useful to collect intermediate results without explicit name
   939 references, and for use with transitivity rules with more than 2
   940 premises;
   941 
   942 * Isar/Pure: scalable support for case-analysis type proofs: new
   943 'case' language element refers to local contexts symbolically, as
   944 produced by certain proof methods; internally, case names are attached
   945 to theorems as "tags";
   946 
   947 * Isar/Pure: theory command 'hide' removes declarations from
   948 class/type/const name spaces;
   949 
   950 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   951 indicate potential overloading;
   952 
   953 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   954 
   955 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   956 "{a,b,c}" instead of {a,b,c};
   957 
   958 * Isar/Pure now provides its own version of intro/elim/dest
   959 attributes; useful for building new logics, but beware of confusion
   960 with the version in Provers/classical;
   961 
   962 * Isar/Pure: the local context of (non-atomic) goals is provided via
   963 case name 'antecedent';
   964 
   965 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   966 to the current context is now done automatically);
   967 
   968 * Isar/Pure: theory command 'method_setup' provides a simple interface
   969 for definining proof methods in ML;
   970 
   971 * Isar/Provers: intro/elim/dest attributes changed; renamed
   972 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   973 most cases, one should have to change intro!! to intro? only);
   974 replaced "delrule" by "rule del";
   975 
   976 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   977 'symmetric' attribute (the latter supercedes [RS sym]);
   978 
   979 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   980 method modifier); 'simp' method: 'only:' modifier removes loopers as
   981 well (including splits);
   982 
   983 * Isar/Provers: Simplifier and Classical methods now support all kind
   984 of modifiers used in the past, including 'cong', 'iff', etc.
   985 
   986 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   987 of Simplifier and Classical reasoner);
   988 
   989 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   990 now support named cases; major packages (inductive, datatype, primrec,
   991 recdef) support case names and properly name parameters;
   992 
   993 * Isar/HOL: new transitivity rules for substitution in inequalities --
   994 monotonicity conditions are extracted to be proven at end of
   995 calculations;
   996 
   997 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   998 method anyway;
   999 
  1000 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1001 split_if split_if_asm; datatype package provides theorems foo.splits =
  1002 foo.split foo.split_asm for each datatype;
  1003 
  1004 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1005 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1006 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1007 use "(cases (simplified))" method in proper proof texts);
  1008 
  1009 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1010 
  1011 * Isar: names of theorems etc. may be natural numbers as well;
  1012 
  1013 * Isar: 'pr' command: optional arguments for goals_limit and
  1014 ProofContext.prems_limit; no longer prints theory contexts, but only
  1015 proof states;
  1016 
  1017 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1018 additional print modes to be specified; e.g. "pr(latex)" will print
  1019 proof state according to the Isabelle LaTeX style;
  1020 
  1021 * Isar: improved support for emulating tactic scripts, including proof
  1022 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1023 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1024 (for HOL datatypes);
  1025 
  1026 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1027 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1028 'proof method scripts' have to be in depth-first order;
  1029 
  1030 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1031 
  1032 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1033 should instead use individual commands for printing items
  1034 (print_commands, print_methods etc.);
  1035 
  1036 * Isar: added 'nothing' --- the empty list of theorems;
  1037 
  1038 
  1039 *** HOL ***
  1040 
  1041 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1042 corresponding virtual machine and a specification of its bytecode
  1043 verifier and a lightweight bytecode verifier, including proofs of
  1044 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1045 Cornelia Pusch (see also the homepage of project Bali at
  1046 http://isabelle.in.tum.de/Bali/);
  1047 
  1048 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1049 Clemens Ballarin;
  1050 
  1051 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1052 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1053 Rasmussen;
  1054 
  1055 * HOL/Lattice: fundamental concepts of lattice theory and order
  1056 structures, including duals, properties of bounds versus algebraic
  1057 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1058 Theorem for complete lattices etc.; may also serve as a demonstration
  1059 for abstract algebraic reasoning using axiomatic type classes, and
  1060 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1061 
  1062 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1063 von Oheimb;
  1064 
  1065 * HOL/IMPP: extension of IMP with local variables and mutually
  1066 recursive procedures, by David von Oheimb;
  1067 
  1068 * HOL/Lambda: converted into new-style theory and document;
  1069 
  1070 * HOL/ex/Multiquote: example of multiple nested quotations and
  1071 anti-quotations -- basically a generalized version of de-Bruijn
  1072 representation; very useful in avoiding lifting of operations;
  1073 
  1074 * HOL/record: added general record equality rule to simpset; fixed
  1075 select-update simplification procedure to handle extended records as
  1076 well; admit "r" as field name;
  1077 
  1078 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1079 other numeric types and also as the identity of groups, rings, etc.;
  1080 
  1081 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1082 Types nat and int belong to this axclass;
  1083 
  1084 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1085    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1086    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1087   two terms #m*u and #n*u are replaced by #(m+n)*u
  1088     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1089   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1090     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1091 
  1092 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1093 powerful prover for predicate logic but knows nothing of clasets; see
  1094 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1095 
  1096 * HOL: new version of "case_tac" subsumes both boolean case split and
  1097 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1098 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1099 
  1100 * HOL: simplification no longer dives into case-expressions: only the
  1101 selector expression is simplified, but not the remaining arms; to
  1102 enable full simplification of case-expressions for datatype t, you may
  1103 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1104 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1105 
  1106 * HOL/recdef: the recursion equations generated by 'recdef' for
  1107 function 'f' are now called f.simps instead of f.rules; if all
  1108 termination conditions are proved automatically, these simplification
  1109 rules are added to the simpset, as in primrec; rules may be named
  1110 individually as well, resulting in a separate list of theorems for
  1111 each equation;
  1112 
  1113 * HOL/While is a new theory that provides a while-combinator. It
  1114 permits the definition of tail-recursive functions without the
  1115 provision of a termination measure. The latter is necessary once the
  1116 invariant proof rule for while is applied.
  1117 
  1118 * HOL: new (overloaded) notation for the set of elements below/above
  1119 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1120 
  1121 * HOL: theorems impI, allI, ballI bound as "strip";
  1122 
  1123 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1124 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1125 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1126 
  1127 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1128 
  1129 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1130 main HOL, but was unused);
  1131 
  1132 * HOL: fewer consts declared as global (e.g. have to refer to
  1133 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1134 
  1135 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1136 in case of overlap with user translations (e.g. judgements over
  1137 tuples); (note that the underlying logical represenation is still
  1138 bogus);
  1139 
  1140 
  1141 *** ZF ***
  1142 
  1143 * ZF: simplification automatically cancels common terms in arithmetic
  1144 expressions over nat and int;
  1145 
  1146 * ZF: new treatment of nat to minimize type-checking: all operators
  1147 coerce their operands to a natural number using the function natify,
  1148 making the algebraic laws unconditional;
  1149 
  1150 * ZF: as above, for int: operators coerce their operands to an integer
  1151 using the function intify;
  1152 
  1153 * ZF: the integer library now contains many of the usual laws for the
  1154 orderings, including $<=, and monotonicity laws for $+ and $*;
  1155 
  1156 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1157 simplification;
  1158 
  1159 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1160 to the simplifier and classical reasoner simultaneously;
  1161 
  1162 
  1163 *** General ***
  1164 
  1165 * Provers: blast_tac now handles actual object-logic rules as
  1166 assumptions; note that auto_tac uses blast_tac internally as well;
  1167 
  1168 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1169 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1170 
  1171 * Provers: delrules now handles destruct rules as well (no longer need
  1172 explicit make_elim);
  1173 
  1174 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1175   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1176 use instead the strong form,
  1177   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1178 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1179 from destruct-rules;
  1180 
  1181 * Provers: Simplifier.easy_setup provides a fast path to basic
  1182 Simplifier setup for new object-logics;
  1183 
  1184 * Pure: AST translation rules no longer require constant head on LHS;
  1185 
  1186 * Pure: improved name spaces: ambiguous output is qualified; support
  1187 for hiding of names;
  1188 
  1189 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1190 XSYMBOL_HOME; no longer need to do manual configuration in most
  1191 situations;
  1192 
  1193 * system: compression of ML heaps images may now be controlled via -c
  1194 option of isabelle and isatool usedir (currently only observed by
  1195 Poly/ML);
  1196 
  1197 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1198 useful for remote X11);
  1199 
  1200 * system: provide TAGS file for Isabelle sources;
  1201 
  1202 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1203 order;
  1204 
  1205 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1206 timing flag supersedes proof_timing and Toplevel.trace;
  1207 
  1208 * ML: new combinators |>> and |>>> for incremental transformations
  1209 with secondary results (e.g. certain theory extensions):
  1210 
  1211 * ML: PureThy.add_defs gets additional argument to indicate potential
  1212 overloading (usually false);
  1213 
  1214 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1215 results;
  1216 
  1217 
  1218 
  1219 New in Isabelle99 (October 1999)
  1220 --------------------------------
  1221 
  1222 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1223 
  1224 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1225 are no longer simplified.  (This allows the simplifier to unfold recursive
  1226 functional programs.)  To restore the old behaviour, declare
  1227 
  1228     Delcongs [if_weak_cong];
  1229 
  1230 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1231 complement;
  1232 
  1233 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1234 
  1235 * HOL/datatype: mutual_induct_tac no longer exists --
  1236   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1237 
  1238 * HOL/typedef: fixed type inference for representing set; type
  1239 arguments now have to occur explicitly on the rhs as type constraints;
  1240 
  1241 * ZF: The con_defs part of an inductive definition may no longer refer
  1242 to constants declared in the same theory;
  1243 
  1244 * HOL, ZF: the function mk_cases, generated by the inductive
  1245 definition package, has lost an argument.  To simplify its result, it
  1246 uses the default simpset instead of a supplied list of theorems.
  1247 
  1248 * HOL/List: the constructors of type list are now Nil and Cons;
  1249 
  1250 * Simplifier: the type of the infix ML functions
  1251         setSSolver addSSolver setSolver addSolver
  1252 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1253 for packaging solvers. A solver is created via
  1254         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1255 where the string argument is only a comment.
  1256 
  1257 
  1258 *** Proof tools ***
  1259 
  1260 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1261 decision procedure for linear arithmetic. Currently it is used for
  1262 types `nat', `int', and `real' in HOL (see below); it can, should and
  1263 will be instantiated for other types and logics as well.
  1264 
  1265 * The simplifier now accepts rewrite rules with flexible heads, eg
  1266      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1267   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1268   matching.
  1269 
  1270 
  1271 *** General ***
  1272 
  1273 * New Isabelle/Isar subsystem provides an alternative to traditional
  1274 tactical theorem proving; together with the ProofGeneral/isar user
  1275 interface it offers an interactive environment for developing human
  1276 readable proof documents (Isar == Intelligible semi-automated
  1277 reasoning); for further information see isatool doc isar-ref,
  1278 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1279 
  1280 * improved and simplified presentation of theories: better HTML markup
  1281 (including colors), graph views in several sizes; isatool usedir now
  1282 provides a proper interface for user theories (via -P option); actual
  1283 document preparation based on (PDF)LaTeX is available as well (for
  1284 new-style theories only); see isatool doc system for more information;
  1285 
  1286 * native support for Proof General, both for classic Isabelle and
  1287 Isabelle/Isar;
  1288 
  1289 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1290 using the graph browser tool;
  1291 
  1292 * Isabelle manuals now also available as PDF;
  1293 
  1294 * theory loader rewritten from scratch (may not be fully
  1295 bug-compatible); old loadpath variable has been replaced by show_path,
  1296 add_path, del_path, reset_path functions; new operations such as
  1297 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1298 isatool doc ref);
  1299 
  1300 * improved isatool install: option -k creates KDE application icon,
  1301 option -p DIR installs standalone binaries;
  1302 
  1303 * added ML_PLATFORM setting (useful for cross-platform installations);
  1304 more robust handling of platform specific ML images for SML/NJ;
  1305 
  1306 * the settings environment is now statically scoped, i.e. it is never
  1307 created again in sub-processes invoked from isabelle, isatool, or
  1308 Isabelle;
  1309 
  1310 * path element specification '~~' refers to '$ISABELLE_HOME';
  1311 
  1312 * in locales, the "assumes" and "defines" parts may be omitted if
  1313 empty;
  1314 
  1315 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1316 long arrows);
  1317 
  1318 * new print_mode "HTML";
  1319 
  1320 * new flag show_tags controls display of tags of theorems (which are
  1321 basically just comments that may be attached by some tools);
  1322 
  1323 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1324 mode and goal output format:
  1325 
  1326 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1327 244c244
  1328 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1329 ---
  1330 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1331 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1332 181c181
  1333 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1334 ---
  1335 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1336 
  1337 * function bind_thms stores lists of theorems (cf. bind_thm);
  1338 
  1339 * new shorthand tactics ftac, eatac, datac, fatac;
  1340 
  1341 * qed (and friends) now accept "" as result name; in that case the
  1342 theorem is not stored, but proper checks and presentation of the
  1343 result still apply;
  1344 
  1345 * theorem database now also indexes constants "Trueprop", "all",
  1346 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1347 
  1348 
  1349 *** HOL ***
  1350 
  1351 ** HOL arithmetic **
  1352 
  1353 * There are now decision procedures for linear arithmetic over nat and
  1354 int:
  1355 
  1356 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1357 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1358 are treated as atomic; subformulae not involving type `nat' or `int'
  1359 are ignored; quantified subformulae are ignored unless they are
  1360 positive universal or negative existential. The tactic has to be
  1361 invoked by hand and can be a little bit slow. In particular, the
  1362 running time is exponential in the number of occurrences of `min' and
  1363 `max', and `-' on `nat'.
  1364 
  1365 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1366 (negated) (in)equalities among the premises and the conclusion into
  1367 account (i.e. no compound formulae) and does not know about `min' and
  1368 `max', and `-' on `nat'. It is fast and is used automatically by the
  1369 simplifier.
  1370 
  1371 NB: At the moment, these decision procedures do not cope with mixed
  1372 nat/int formulae where the two parts interact, such as `m < n ==>
  1373 int(m) < int(n)'.
  1374 
  1375 * HOL/Numeral provides a generic theory of numerals (encoded
  1376 efficiently as bit strings); setup for types nat/int/real is in place;
  1377 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1378 int, existing theories and proof scripts may require a few additional
  1379 type constraints;
  1380 
  1381 * integer division and remainder can now be performed on constant
  1382 arguments;
  1383 
  1384 * many properties of integer multiplication, division and remainder
  1385 are now available;
  1386 
  1387 * An interface to the Stanford Validity Checker (SVC) is available through the
  1388 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1389 are proved automatically.  SVC must be installed separately, and its results
  1390 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1391 invocation of the underlying oracle).  For SVC see
  1392   http://verify.stanford.edu/SVC
  1393 
  1394 * IsaMakefile: the HOL-Real target now builds an actual image;
  1395 
  1396 
  1397 ** HOL misc **
  1398 
  1399 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1400 (in Isabelle/Isar) -- by Gertrud Bauer;
  1401 
  1402 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1403 analysis for assembly languages with subtypes;
  1404 
  1405 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1406 -- avoids syntactic ambiguities and treats state, transition, and
  1407 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1408 changed syntax and (many) tactics;
  1409 
  1410 * HOL/inductive: Now also handles more general introduction rules such
  1411   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1412   theorems are now maintained within the theory (maintained via the
  1413   "mono" attribute);
  1414 
  1415 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1416   (using function types) such as
  1417 
  1418   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1419 
  1420 * HOL/record: record_simproc (part of the default simpset) takes care
  1421 of selectors applied to updated records; record_split_tac is no longer
  1422 part of the default claset; update_defs may now be removed from the
  1423 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1424 
  1425   claset_ref () := claset() addSWrapper record_split_wrapper;
  1426   Delsimprocs [record_simproc]
  1427 
  1428 * HOL/typedef: fixed type inference for representing set; type
  1429 arguments now have to occur explicitly on the rhs as type constraints;
  1430 
  1431 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1432 names rather than an ML expression;
  1433 
  1434 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1435 supplied later.  Program schemes can be defined, such as
  1436     "While B C s = (if B s then While B C (C s) else s)"
  1437 where the well-founded relation can be chosen after B and C have been given.
  1438 
  1439 * HOL/List: the constructors of type list are now Nil and Cons;
  1440 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1441 course, ML tools referring to List.list.op # etc. have to be adapted;
  1442 
  1443 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1444 disabled by default; run isabelle with option -m HOL to get back to
  1445 the original Gordon/HOL-style output;
  1446 
  1447 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1448 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1449 
  1450 * HOL basic syntax simplified (more orthogonal): all variants of
  1451 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1452 Eps operator is provided as well: "SOME x. P[x]";
  1453 
  1454 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1455 
  1456 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1457 thus available for user theories;
  1458 
  1459 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1460 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1461 time;
  1462 
  1463 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1464 several times and then mp;
  1465 
  1466 
  1467 *** LK ***
  1468 
  1469 * the notation <<...>> is now available as a notation for sequences of
  1470 formulas;
  1471 
  1472 * the simplifier is now installed
  1473 
  1474 * the axiom system has been generalized (thanks to Soren Heilmann)
  1475 
  1476 * the classical reasoner now has a default rule database
  1477 
  1478 
  1479 *** ZF ***
  1480 
  1481 * new primrec section allows primitive recursive functions to be given
  1482 directly (as in HOL) over datatypes and the natural numbers;
  1483 
  1484 * new tactics induct_tac and exhaust_tac for induction (or case
  1485 analysis) over datatypes and the natural numbers;
  1486 
  1487 * the datatype declaration of type T now defines the recursor T_rec;
  1488 
  1489 * simplification automatically does freeness reasoning for datatype
  1490 constructors;
  1491 
  1492 * automatic type-inference, with AddTCs command to insert new
  1493 type-checking rules;
  1494 
  1495 * datatype introduction rules are now added as Safe Introduction rules
  1496 to the claset;
  1497 
  1498 * the syntax "if P then x else y" is now available in addition to
  1499 if(P,x,y);
  1500 
  1501 
  1502 *** Internal programming interfaces ***
  1503 
  1504 * tuned simplifier trace output; new flag debug_simp;
  1505 
  1506 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1507 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1508 
  1509 * AxClass.axclass_tac lost the theory argument;
  1510 
  1511 * tuned current_goals_markers semantics: begin / end goal avoids
  1512 printing empty lines;
  1513 
  1514 * removed prs and prs_fn hook, which was broken because it did not
  1515 include \n in its semantics, forcing writeln to add one
  1516 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1517 string -> unit if you really want to output text without newline;
  1518 
  1519 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1520 plain output, interface builders may have to enable 'isabelle_font'
  1521 mode to get Isabelle font glyphs as before;
  1522 
  1523 * refined token_translation interface; INCOMPATIBILITY: output length
  1524 now of type real instead of int;
  1525 
  1526 * theory loader actions may be traced via new ThyInfo.add_hook
  1527 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1528 your own database of information attached to *whole* theories -- as
  1529 opposed to intra-theory data slots offered via TheoryDataFun;
  1530 
  1531 * proper handling of dangling sort hypotheses (at last!);
  1532 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1533 extra sort hypotheses that can be witnessed from the type signature;
  1534 the force_strip_shyps flag is gone, any remaining shyps are simply
  1535 left in the theorem (with a warning issued by strip_shyps_warning);
  1536 
  1537 
  1538 
  1539 New in Isabelle98-1 (October 1998)
  1540 ----------------------------------
  1541 
  1542 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1543 
  1544 * several changes of automated proof tools;
  1545 
  1546 * HOL: major changes to the inductive and datatype packages, including
  1547 some minor incompatibilities of theory syntax;
  1548 
  1549 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1550 called `inj_on';
  1551 
  1552 * HOL: removed duplicate thms in Arith:
  1553   less_imp_add_less  should be replaced by  trans_less_add1
  1554   le_imp_add_le      should be replaced by  trans_le_add1
  1555 
  1556 * HOL: unary minus is now overloaded (new type constraints may be
  1557 required);
  1558 
  1559 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1560 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1561 now taken as an integer constant.
  1562 
  1563 * Pure: ML function 'theory_of' renamed to 'theory';
  1564 
  1565 
  1566 *** Proof tools ***
  1567 
  1568 * Simplifier:
  1569   1. Asm_full_simp_tac is now more aggressive.
  1570      1. It will sometimes reorient premises if that increases their power to
  1571         simplify.
  1572      2. It does no longer proceed strictly from left to right but may also
  1573         rotate premises to achieve further simplification.
  1574      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1575      old Asm_full_simp_tac in that it does not rotate premises.
  1576   2. The simplifier now knows a little bit about nat-arithmetic.
  1577 
  1578 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1579 allows for selected deletion of wrappers, by introduction of names for
  1580 wrapper functionals.  This implies that addbefore, addSbefore,
  1581 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1582 and that adding two tactics with the same name overwrites the first
  1583 one (emitting a warning).
  1584   type wrapper = (int -> tactic) -> (int -> tactic)
  1585   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1586   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1587   delWrapper, delSWrapper: claset *  string            -> claset
  1588   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1589 
  1590 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1591 semantics; addbefore now affects only the unsafe part of step_tac
  1592 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1593 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1594 by Force_tac;
  1595 
  1596 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1597 compWrapper; added safe wrapper (and access functions for it);
  1598 
  1599 * HOL/split_all_tac is now much faster and fails if there is nothing
  1600 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1601 and the names of the automatically generated variables have changed.
  1602 split_all_tac has moved within claset() from unsafe wrappers to safe
  1603 wrappers, which means that !!-bound variables are split much more
  1604 aggressively, and safe_tac and clarify_tac now split such variables.
  1605 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1606 Note: the same holds for record_split_tac, which does the job of
  1607 split_all_tac for record fields.
  1608 
  1609 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1610 permanently to the default simpset using Addsplits just like
  1611 Addsimps. They can be removed via Delsplits just like
  1612 Delsimps. Lower-case versions are also available.
  1613 
  1614 * HOL/Simplifier: The rule split_if is now part of the default
  1615 simpset. This means that the simplifier will eliminate all occurrences
  1616 of if-then-else in the conclusion of a goal. To prevent this, you can
  1617 either remove split_if completely from the default simpset by
  1618 `Delsplits [split_if]' or remove it in a specific call of the
  1619 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1620 other case splitting rules to/from the default simpset: every datatype
  1621 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1622 t is the name of the datatype).
  1623 
  1624 * Classical reasoner / Simplifier combination: new force_tac (and
  1625 derivatives Force_tac, force) combines rewriting and classical
  1626 reasoning (and whatever other tools) similarly to auto_tac, but is
  1627 aimed to solve the given subgoal completely.
  1628 
  1629 
  1630 *** General ***
  1631 
  1632 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1633 and `goalw': the theory is no longer needed as an explicit argument -
  1634 the current theory context is used; assumptions are no longer returned
  1635 at the ML-level unless one of them starts with ==> or !!; it is
  1636 recommended to convert to these new commands using isatool fixgoal
  1637 (backup your sources first!);
  1638 
  1639 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1640 the current theory context, and 'theory' to lookup stored theories;
  1641 
  1642 * new theory section 'locale' for declaring constants, assumptions and
  1643 definitions that have local scope;
  1644 
  1645 * new theory section 'nonterminals' for purely syntactic types;
  1646 
  1647 * new theory section 'setup' for generic ML setup functions
  1648 (e.g. package initialization);
  1649 
  1650 * the distribution now includes Isabelle icons: see
  1651 lib/logo/isabelle-{small,tiny}.xpm;
  1652 
  1653 * isatool install - install binaries with absolute references to
  1654 ISABELLE_HOME/bin;
  1655 
  1656 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1657 
  1658 * print mode 'emacs' reserved for Isamode;
  1659 
  1660 * support multiple print (ast) translations per constant name;
  1661 
  1662 * theorems involving oracles are now printed with a suffixed [!];
  1663 
  1664 
  1665 *** HOL ***
  1666 
  1667 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1668 
  1669 * HOL/inductive package reorganized and improved: now supports mutual
  1670 definitions such as
  1671 
  1672   inductive EVEN ODD
  1673     intrs
  1674       null "0 : EVEN"
  1675       oddI "n : EVEN ==> Suc n : ODD"
  1676       evenI "n : ODD ==> Suc n : EVEN"
  1677 
  1678 new theorem list "elims" contains an elimination rule for each of the
  1679 recursive sets; inductive definitions now handle disjunctive premises
  1680 correctly (also ZF);
  1681 
  1682 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1683 "mutual_induct" no longer exists - the induction rule is always
  1684 contained in "induct";
  1685 
  1686 
  1687 * HOL/datatype package re-implemented and greatly improved: now
  1688 supports mutually recursive datatypes such as
  1689 
  1690   datatype
  1691     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1692             | SUM ('a aexp) ('a aexp)
  1693             | DIFF ('a aexp) ('a aexp)
  1694             | NUM 'a
  1695   and
  1696     'a bexp = LESS ('a aexp) ('a aexp)
  1697             | AND ('a bexp) ('a bexp)
  1698             | OR ('a bexp) ('a bexp)
  1699 
  1700 as well as indirectly recursive datatypes such as
  1701 
  1702   datatype
  1703     ('a, 'b) term = Var 'a
  1704                   | App 'b ((('a, 'b) term) list)
  1705 
  1706 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1707 induction on mutually / indirectly recursive datatypes.
  1708 
  1709 Primrec equations are now stored in theory and can be accessed via
  1710 <function_name>.simps.
  1711 
  1712 INCOMPATIBILITIES:
  1713 
  1714   - Theories using datatypes must now have theory Datatype as an
  1715     ancestor.
  1716   - The specific <typename>.induct_tac no longer exists - use the
  1717     generic induct_tac instead.
  1718   - natE has been renamed to nat.exhaust - use exhaust_tac
  1719     instead of res_inst_tac ... natE. Note that the variable
  1720     names in nat.exhaust differ from the names in natE, this
  1721     may cause some "fragile" proofs to fail.
  1722   - The theorems split_<typename>_case and split_<typename>_case_asm
  1723     have been renamed to <typename>.split and <typename>.split_asm.
  1724   - Since default sorts of type variables are now handled correctly,
  1725     some datatype definitions may have to be annotated with explicit
  1726     sort constraints.
  1727   - Primrec definitions no longer require function name and type
  1728     of recursive argument.
  1729 
  1730 Consider using isatool fixdatatype to adapt your theories and proof
  1731 scripts to the new package (backup your sources first!).
  1732 
  1733 
  1734 * HOL/record package: considerably improved implementation; now
  1735 includes concrete syntax for record types, terms, updates; theorems
  1736 for surjective pairing and splitting !!-bound record variables; proof
  1737 support is as follows:
  1738 
  1739   1) standard conversions (selectors or updates applied to record
  1740 constructor terms) are part of the standard simpset;
  1741 
  1742   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1743 made part of standard simpset and claset via addIffs;
  1744 
  1745   3) a tactic for record field splitting (record_split_tac) is part of
  1746 the standard claset (addSWrapper);
  1747 
  1748 To get a better idea about these rules you may retrieve them via
  1749 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1750 the name of your record type.
  1751 
  1752 The split tactic 3) conceptually simplifies by the following rule:
  1753 
  1754   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1755 
  1756 Thus any record variable that is bound by meta-all will automatically
  1757 blow up into some record constructor term, consequently the
  1758 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1759 solve record problems automatically.
  1760 
  1761 
  1762 * reorganized the main HOL image: HOL/Integ and String loaded by
  1763 default; theory Main includes everything;
  1764 
  1765 * automatic simplification of integer sums and comparisons, using cancellation;
  1766 
  1767 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1768 
  1769 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1770 
  1771 * many new identities for unions, intersections, set difference, etc.;
  1772 
  1773 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1774 called split_if, split_split, split_sum_case and split_nat_case (to go
  1775 with add/delsplits);
  1776 
  1777 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1778 (?x::unit) = (); this is made part of the default simpset, which COULD
  1779 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1780 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1781 unit_abs_eta_conv is added in order to counter the effect of
  1782 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1783 %u.f();
  1784 
  1785 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1786 makes more sense);
  1787 
  1788 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1789   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1790   disjointness reasoning but breaking a few old proofs.
  1791 
  1792 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1793 to 'converse' from 'inverse' (for compatibility with ZF and some
  1794 literature);
  1795 
  1796 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1797 the well-founded relation;
  1798 
  1799 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1800     Compl A.  The "Compl" syntax remains available as input syntax for this
  1801     release ONLY.
  1802 
  1803 * HOL/Update: new theory of function updates:
  1804     f(a:=b) == %x. if x=a then b else f x
  1805 may also be iterated as in f(a:=b,c:=d,...);
  1806 
  1807 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1808 
  1809 * HOL/List:
  1810   - new function list_update written xs[i:=v] that updates the i-th
  1811     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1812   - new function `upt' written [i..j(] which generates the list
  1813     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1814     bound write [i..j], which is a shorthand for [i..j+1(].
  1815   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1816 
  1817 * HOL/Arith:
  1818   - removed 'pred' (predecessor) function;
  1819   - generalized some theorems about n-1;
  1820   - many new laws about "div" and "mod";
  1821   - new laws about greatest common divisors (see theory ex/Primes);
  1822 
  1823 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1824 instead of "inverse";
  1825 
  1826 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1827   of the multiset ordering;
  1828 
  1829 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1830   (not included by default);
  1831 
  1832 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1833 
  1834 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1835   programs, i.e. different program variables may have different types.
  1836 
  1837 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1838   [previously, this check worked only if the rewrite rule was unconditional]
  1839   Now rew can involve either definitions or equalities (either == or =).
  1840 
  1841 
  1842 *** ZF ***
  1843 
  1844 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1845   only the theorems proved on ZF.ML;
  1846 
  1847 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1848   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1849   disjointness reasoning but breaking a few old proofs.
  1850 
  1851 * ZF/Update: new theory of function updates
  1852     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1853   may also be iterated as in f(a:=b,c:=d,...);
  1854 
  1855 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1856 
  1857 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1858   [previously, this check worked only if the rewrite rule was unconditional]
  1859   Now rew can involve either definitions or equalities (either == or =).
  1860 
  1861 * case_tac provided for compatibility with HOL
  1862     (like the old excluded_middle_tac, but with subgoals swapped)
  1863 
  1864 
  1865 *** Internal programming interfaces ***
  1866 
  1867 * Pure: several new basic modules made available for general use, see
  1868 also src/Pure/README;
  1869 
  1870 * improved the theory data mechanism to support encapsulation (data
  1871 kind name replaced by private Object.kind, acting as authorization
  1872 key); new type-safe user interface via functor TheoryDataFun; generic
  1873 print_data function becomes basically useless;
  1874 
  1875 * removed global_names compatibility flag -- all theory declarations
  1876 are qualified by default;
  1877 
  1878 * module Pure/Syntax now offers quote / antiquote translation
  1879 functions (useful for Hoare logic etc. with implicit dependencies);
  1880 see HOL/ex/Antiquote for an example use;
  1881 
  1882 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1883 cterm -> thm;
  1884 
  1885 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1886 subgoal;
  1887 
  1888 * Display.print_goals function moved to Locale.print_goals;
  1889 
  1890 * standard print function for goals supports current_goals_markers
  1891 variable for marking begin of proof, end of proof, start of goal; the
  1892 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1893 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1894 for example;
  1895 
  1896 
  1897 
  1898 New in Isabelle98 (January 1998)
  1899 --------------------------------
  1900 
  1901 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1902 
  1903 * changed lexical syntax of terms / types: dots made part of long
  1904 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1905 
  1906 * simpset (and claset) reference variable replaced by functions
  1907 simpset / simpset_ref;
  1908 
  1909 * no longer supports theory aliases (via merge) and non-trivial
  1910 implicit merge of thms' signatures;
  1911 
  1912 * most internal names of constants changed due to qualified names;
  1913 
  1914 * changed Pure/Sequence interface (see Pure/seq.ML);
  1915 
  1916 
  1917 *** General Changes ***
  1918 
  1919 * hierachically structured name spaces (for consts, types, axms, thms
  1920 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1921 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1922 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1923 long_names for fully qualified output names; NOTE: ML programs
  1924 (special tactics, packages etc.) referring to internal names may have
  1925 to be adapted to cope with fully qualified names; in case of severe
  1926 backward campatibility problems try setting 'global_names' at compile
  1927 time to have enrything declared within a flat name space; one may also
  1928 fine tune name declarations in theories via the 'global' and 'local'
  1929 section;
  1930 
  1931 * reimplemented the implicit simpset and claset using the new anytype
  1932 data filed in signatures; references simpset:simpset ref etc. are
  1933 replaced by functions simpset:unit->simpset and
  1934 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1935 to patch your ML files accordingly;
  1936 
  1937 * HTML output now includes theory graph data for display with Java
  1938 applet or isatool browser; data generated automatically via isatool
  1939 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1940 
  1941 * defs may now be conditional; improved rewrite_goals_tac to handle
  1942 conditional equations;
  1943 
  1944 * defs now admits additional type arguments, using TYPE('a) syntax;
  1945 
  1946 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1947 creates a new theory node; implicit merge of thms' signatures is
  1948 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1949 transfer:theory->thm->thm in (rare) cases;
  1950 
  1951 * improved handling of draft signatures / theories; draft thms (and
  1952 ctyps, cterms) are automatically promoted to real ones;
  1953 
  1954 * slightly changed interfaces for oracles: admit many per theory, named
  1955 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1956 
  1957 * print_goals: optional output of const types (set show_consts and
  1958 show_types);
  1959 
  1960 * improved output of warnings (###) and errors (***);
  1961 
  1962 * subgoal_tac displays a warning if the new subgoal has type variables;
  1963 
  1964 * removed old README and Makefiles;
  1965 
  1966 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1967 
  1968 * removed obsolete init_pps and init_database;
  1969 
  1970 * deleted the obsolete tactical STATE, which was declared by
  1971     fun STATE tacfun st = tacfun st st;
  1972 
  1973 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1974 (which abbreviates $HOME);
  1975 
  1976 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1977 use isatool fixseq to adapt your ML programs (this works for fully
  1978 qualified references to the Sequence structure only!);
  1979 
  1980 * use_thy no longer requires writable current directory; it always
  1981 reloads .ML *and* .thy file, if either one is out of date;
  1982 
  1983 
  1984 *** Classical Reasoner ***
  1985 
  1986 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1987 tactics that use classical reasoning to simplify a subgoal without
  1988 splitting it into several subgoals;
  1989 
  1990 * Safe_tac: like safe_tac but uses the default claset;
  1991 
  1992 
  1993 *** Simplifier ***
  1994 
  1995 * added simplification meta rules:
  1996     (asm_)(full_)simplify: simpset -> thm -> thm;
  1997 
  1998 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1999 logics (again);
  2000 
  2001 * added prems argument to simplification procedures;
  2002 
  2003 * HOL, FOL, ZF: added infix function `addsplits':
  2004   instead of `<simpset> setloop (split_tac <thms>)'
  2005   you can simply write `<simpset> addsplits <thms>'
  2006 
  2007 
  2008 *** Syntax ***
  2009 
  2010 * TYPE('a) syntax for type reflection terms;
  2011 
  2012 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2013 
  2014 * pretty printer: changed order of mixfix annotation preference (again!);
  2015 
  2016 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2017 
  2018 
  2019 *** HOL ***
  2020 
  2021 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2022   with `addloop' of the simplifier to faciliate case splitting in premises.
  2023 
  2024 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2025 
  2026 * HOL/Auth: new protocol proofs including some for the Internet
  2027   protocol TLS;
  2028 
  2029 * HOL/Map: new theory of `maps' a la VDM;
  2030 
  2031 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2032 cancelling out common nat summands from =, <, <= (in)equalities, or
  2033 differences; simplification procedures nat_cancel_factor for
  2034 cancelling common factor from =, <, <= (in)equalities over natural
  2035 sums; nat_cancel contains both kinds of procedures, it is installed by
  2036 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2037 
  2038 * HOL/simplifier: terms of the form
  2039   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2040   are rewritten to
  2041   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2042   and those of the form
  2043   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2044   are rewritten to
  2045   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2046 
  2047 * HOL/datatype
  2048   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2049 
  2050   P(t_case f1 ... fn x) =
  2051      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2052         ...
  2053        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2054      )
  2055 
  2056   and a theorem `split_t_case_asm' of the form
  2057 
  2058   P(t_case f1 ... fn x) =
  2059     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2060         ...
  2061        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2062      )
  2063   which can be added to a simpset via `addsplits'. The existing theorems
  2064   expand_list_case and expand_option_case have been renamed to
  2065   split_list_case and split_option_case.
  2066 
  2067 * HOL/Arithmetic:
  2068   - `pred n' is automatically converted to `n-1'.
  2069     Users are strongly encouraged not to use `pred' any longer,
  2070     because it will disappear altogether at some point.
  2071   - Users are strongly encouraged to write "0 < n" rather than
  2072     "n ~= 0". Theorems and proof tools have been modified towards this
  2073     `standard'.
  2074 
  2075 * HOL/Lists:
  2076   the function "set_of_list" has been renamed "set" (and its theorems too);
  2077   the function "nth" now takes its arguments in the reverse order and
  2078   has acquired the infix notation "!" as in "xs!n".
  2079 
  2080 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2081 
  2082 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2083   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2084 
  2085 * HOL/record: extensible records with schematic structural subtyping
  2086 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2087 still lacks various theorems and concrete record syntax;
  2088 
  2089 
  2090 *** HOLCF ***
  2091 
  2092 * removed "axioms" and "generated by" sections;
  2093 
  2094 * replaced "ops" section by extended "consts" section, which is capable of
  2095   handling the continuous function space "->" directly;
  2096 
  2097 * domain package:
  2098   . proves theorems immediately and stores them in the theory,
  2099   . creates hierachical name space,
  2100   . now uses normal mixfix annotations (instead of cinfix...),
  2101   . minor changes to some names and values (for consistency),
  2102   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2103   . separator between mutual domain defs: changed "," to "and",
  2104   . improved handling of sort constraints;  now they have to
  2105     appear on the left-hand side of the equations only;
  2106 
  2107 * fixed LAM <x,y,zs>.b syntax;
  2108 
  2109 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2110 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2111 
  2112 
  2113 *** FOL and ZF ***
  2114 
  2115 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2116   with `addloop' of the simplifier to faciliate case splitting in premises.
  2117 
  2118 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2119 in HOL, they strip ALL and --> from proved theorems;
  2120 
  2121 
  2122 
  2123 New in Isabelle94-8 (May 1997)
  2124 ------------------------------
  2125 
  2126 *** General Changes ***
  2127 
  2128 * new utilities to build / run / maintain Isabelle etc. (in parts
  2129 still somewhat experimental); old Makefiles etc. still functional;
  2130 
  2131 * new 'Isabelle System Manual';
  2132 
  2133 * INSTALL text, together with ./configure and ./build scripts;
  2134 
  2135 * reimplemented type inference for greater efficiency, better error
  2136 messages and clean internal interface;
  2137 
  2138 * prlim command for dealing with lots of subgoals (an easier way of
  2139 setting goals_limit);
  2140 
  2141 
  2142 *** Syntax ***
  2143 
  2144 * supports alternative (named) syntax tables (parser and pretty
  2145 printer); internal interface is provided by add_modesyntax(_i);
  2146 
  2147 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2148 be used in conjunction with the Isabelle symbol font; uses the
  2149 "symbols" syntax table;
  2150 
  2151 * added token_translation interface (may translate name tokens in
  2152 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2153 the current print_mode); IMPORTANT: user print translation functions
  2154 are responsible for marking newly introduced bounds
  2155 (Syntax.mark_boundT);
  2156 
  2157 * token translations for modes "xterm" and "xterm_color" that display
  2158 names in bold, underline etc. or colors (which requires a color
  2159 version of xterm);
  2160 
  2161 * infixes may now be declared with names independent of their syntax;
  2162 
  2163 * added typed_print_translation (like print_translation, but may
  2164 access type of constant);
  2165 
  2166 
  2167 *** Classical Reasoner ***
  2168 
  2169 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2170 some limitations.  Blast_tac...
  2171   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2172   + ignores elimination rules that don't have the correct format
  2173         (the conclusion MUST be a formula variable)
  2174   + ignores types, which can make HOL proofs fail
  2175   + rules must not require higher-order unification, e.g. apply_type in ZF
  2176     [message "Function Var's argument not a bound variable" relates to this]
  2177   + its proof strategy is more general but can actually be slower
  2178 
  2179 * substitution with equality assumptions no longer permutes other
  2180 assumptions;
  2181 
  2182 * minor changes in semantics of addafter (now called addaltern); renamed
  2183 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2184 (and access functions for it);
  2185 
  2186 * improved combination of classical reasoner and simplifier:
  2187   + functions for handling clasimpsets
  2188   + improvement of addss: now the simplifier is called _after_ the
  2189     safe steps.
  2190   + safe variant of addss called addSss: uses safe simplifications
  2191     _during_ the safe steps. It is more complete as it allows multiple
  2192     instantiations of unknowns (e.g. with slow_tac).
  2193 
  2194 *** Simplifier ***
  2195 
  2196 * added interface for simplification procedures (functions that
  2197 produce *proven* rewrite rules on the fly, depending on current
  2198 redex);
  2199 
  2200 * ordering on terms as parameter (used for ordered rewriting);
  2201 
  2202 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2203 
  2204 * the solver is now split into a safe and an unsafe part.
  2205 This should be invisible for the normal user, except that the
  2206 functions setsolver and addsolver have been renamed to setSolver and
  2207 addSolver; added safe_asm_full_simp_tac;
  2208 
  2209 
  2210 *** HOL ***
  2211 
  2212 * a generic induction tactic `induct_tac' which works for all datatypes and
  2213 also for type `nat';
  2214 
  2215 * a generic case distinction tactic `exhaust_tac' which works for all
  2216 datatypes and also for type `nat';
  2217 
  2218 * each datatype comes with a function `size';
  2219 
  2220 * patterns in case expressions allow tuple patterns as arguments to
  2221 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2222 
  2223 * primrec now also works with type nat;
  2224 
  2225 * recdef: a new declaration form, allows general recursive functions to be
  2226 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2227 
  2228 * the constant for negation has been renamed from "not" to "Not" to
  2229 harmonize with FOL, ZF, LK, etc.;
  2230 
  2231 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2232 infinite lists;
  2233 
  2234 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2235 
  2236 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2237 problems in commutative rings, using axiomatic type classes for + and *;
  2238 
  2239 * more examples in HOL/MiniML and HOL/Auth;
  2240 
  2241 * more default rewrite rules for quantifiers, union/intersection;
  2242 
  2243 * a new constant `arbitrary == @x.False';
  2244 
  2245 * HOLCF/IOA replaces old HOL/IOA;
  2246 
  2247 * HOLCF changes: derived all rules and arities
  2248   + axiomatic type classes instead of classes
  2249   + typedef instead of faking type definitions
  2250   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2251   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2252   + eliminated the types void, one, tr
  2253   + use unit lift and bool lift (with translations) instead of one and tr
  2254   + eliminated blift from Lift3.thy (use Def instead of blift)
  2255   all eliminated rules are derived as theorems --> no visible changes ;
  2256 
  2257 
  2258 *** ZF ***
  2259 
  2260 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2261 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2262 as ZF_cs addSIs [equalityI];
  2263 
  2264 
  2265 
  2266 New in Isabelle94-7 (November 96)
  2267 ---------------------------------
  2268 
  2269 * allowing negative levels (as offsets) in prlev and choplev;
  2270 
  2271 * super-linear speedup for large simplifications;
  2272 
  2273 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2274 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2275 FAIL); can suppress it using the command Delsimps (ex_simps @
  2276 all_simps); De Morgan laws are also now included, by default;
  2277 
  2278 * improved printing of ==>  :  ~:
  2279 
  2280 * new object-logic "Sequents" adds linear logic, while replacing LK
  2281 and Modal (thanks to Sara Kalvala);
  2282 
  2283 * HOL/Auth: correctness proofs for authentication protocols;
  2284 
  2285 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2286 examples on HOL/Auth);
  2287 
  2288 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2289 the rewriter and classical reasoner simultaneously;
  2290 
  2291 * function uresult no longer returns theorems in "standard" format;
  2292 regain previous version by: val uresult = standard o uresult;
  2293 
  2294 
  2295 
  2296 New in Isabelle94-6
  2297 -------------------
  2298 
  2299 * oracles -- these establish an interface between Isabelle and trusted
  2300 external reasoners, which may deliver results as theorems;
  2301 
  2302 * proof objects (in particular record all uses of oracles);
  2303 
  2304 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2305 
  2306 * "constdefs" section in theory files;
  2307 
  2308 * "primrec" section (HOL) no longer requires names;
  2309 
  2310 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2311 
  2312 
  2313 
  2314 New in Isabelle94-5
  2315 -------------------
  2316 
  2317 * reduced space requirements;
  2318 
  2319 * automatic HTML generation from theories;
  2320 
  2321 * theory files no longer require "..." (quotes) around most types;
  2322 
  2323 * new examples, including two proofs of the Church-Rosser theorem;
  2324 
  2325 * non-curried (1994) version of HOL is no longer distributed;
  2326 
  2327 
  2328 
  2329 New in Isabelle94-4
  2330 -------------------
  2331 
  2332 * greatly reduced space requirements;
  2333 
  2334 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2335 
  2336 * searchable theorem database (see the section "Retrieving theorems" on
  2337 page 8 of the Reference Manual);
  2338 
  2339 * new examples, including Grabczewski's monumental case study of the
  2340 Axiom of Choice;
  2341 
  2342 * The previous version of HOL renamed to Old_HOL;
  2343 
  2344 * The new version of HOL (previously called CHOL) uses a curried syntax
  2345 for functions.  Application looks like f a b instead of f(a,b);
  2346 
  2347 * Mutually recursive inductive definitions finally work in HOL;
  2348 
  2349 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2350 translates to the operator "split";
  2351 
  2352 
  2353 
  2354 New in Isabelle94-3
  2355 -------------------
  2356 
  2357 * new infix operator, addss, allowing the classical reasoner to
  2358 perform simplification at each step of its search.  Example:
  2359         fast_tac (cs addss ss)
  2360 
  2361 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2362 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2363 look like (a,b) instead of <a,b>;
  2364 
  2365 * PLEASE NOTE: CHOL will eventually replace HOL!
  2366 
  2367 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2368 It translates to the operator "split".  A new theory of integers is available;
  2369 
  2370 * In ZF, integer numerals now denote two's-complement binary integers.
  2371 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2372 
  2373 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2374 of the Axiom of Choice;
  2375 
  2376 
  2377 
  2378 New in Isabelle94-2
  2379 -------------------
  2380 
  2381 * Significantly faster resolution;
  2382 
  2383 * the different sections in a .thy file can now be mixed and repeated
  2384 freely;
  2385 
  2386 * Database of theorems for FOL, HOL and ZF.  New
  2387 commands including qed, qed_goal and bind_thm store theorems in the database.
  2388 
  2389 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2390 a given theory (thms_of), or find out what theory a theorem was proved in
  2391 (theory_of_thm);
  2392 
  2393 * Bugs fixed in the inductive definition and datatype packages;
  2394 
  2395 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2396 and HOL_dup_cs obsolete;
  2397 
  2398 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2399 have been removed;
  2400 
  2401 * Simpler definition of function space in ZF;
  2402 
  2403 * new results about cardinal and ordinal arithmetic in ZF;
  2404 
  2405 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2406 types;
  2407 
  2408 
  2409 $Id$