NEWS
author nipkow
Wed Feb 11 00:37:18 2004 +0100 (2004-02-11)
changeset 14380 04b603a6f17d
parent 14375 a545da363b23
child 14389 57c2d90936ba
permissions -rw-r--r--
*** empty log message ***
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** General ***
     8 
     9 * Pure: Greek letters (except small lambda, \<lambda>), as well as gothic
    10   (\<aa>...\<zz>\<AA>...\<ZZ>), caligraphic (\<A>...\<Z>), and euler
    11   (\<a>...\<z>), are now considered normal letters, and can therefore
    12   be used anywhere where an ASCII letter (a...zA...Z) has until
    13   now. COMPATIBILITY: This obviously changes the parsing of some
    14   terms, especially where a symbol has been used as a binder, say
    15   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed
    16   as an identifier.  Fix it by inserting a space around former
    17   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in
    18   existing theory and ML files.
    19 
    20 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.
    21 
    22 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now 
    23   allowed in identifiers. Similar to greek letters \<^isub> is now considered 
    24   a normal (but invisible) letter. For multiple letter subscripts repeat 
    25   \<^isub> like this: x\<^isub>1\<^isub>2. 
    26 
    27 * Pure: There are now sub-/superscripts that can span more than one
    28   character. Text between \<^bsub> and \<^esub> is set in subscript in
    29   PG and LaTeX, text between \<^bsup> and \<^esup> in superscript. The
    30   new control characters are not identifier parts.
    31 
    32 * Pure: Control-symbols of the form \<^raw...> will literally print the
    33   content of ... to the latex file instead of \isacntrl... . The ... 
    34   accepts all printable characters excluding the end bracket >.
    35 
    36 * Pure: Symbols may only start with one backslash: \<...>. \\<...> is no 
    37   longer accepted by the scanner.
    38 
    39 * Pure: Using new Isar command "finalconsts" (or the ML functions
    40   Theory.add_finals or Theory.add_finals_i) it is now possible to
    41   declare constants "final", which prevents their being given a definition
    42   later.  It is useful for constants whose behaviour is fixed axiomatically
    43   rather than definitionally, such as the meta-logic connectives.
    44 
    45 *** Isar ***
    46 
    47 * Tactic emulation methods ?rule_tac, cut_tac, subgoal_tac and thin_tac:
    48   - Now understand static (Isar) contexts.  As a consequence, users of Isar
    49     locales are no longer forced to write Isar proof scripts.
    50     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
    51     emulations.
    52   - INCOMPATIBILITY: names of variables to be instantiated may no
    53     longer be enclosed in quotes.  Instead, precede variable name with `?'.
    54     This is consistent with the instantiation attribute "where".
    55 
    56 * Attributes "where" and "of":
    57   - Now take type variables of instantiated theorem into account when reading
    58     the instantiation string.  This fixes a bug that caused instantiated
    59     theorems to have too special types in some circumstances.
    60   - "where" permits explicit instantiations of type variables.
    61 
    62 * Calculation commands "moreover" and "also":
    63   Do not reset facts ("this") any more.
    64 
    65 * Locales:
    66   - Goal statements involving the context element "includes" no longer
    67     generate theorems with internal delta predicates (those ending on
    68     "_axioms") in the premise.
    69     Resolve particular premise with <locale>.intro to obtain old form.
    70   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
    71     specification and "includes" elements in goal statement.
    72   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
    73     [intro?] and [elim?] (respectively) by default.
    74 
    75 * HOL: Tactic emulation methods induct_tac and case_tac understand static
    76   (Isar) contexts.
    77 
    78 *** HOL ***
    79 
    80 * Records:
    81   - Record types are now by default printed with their type abbreviation
    82     instead of the list of all field types. This can be configured via
    83     the reference "print_record_type_abbr".
    84   - Simproc "record_upd_simproc" for simplification of multiple updates added 
    85     (not enabled by default).
    86   - Tactic "record_split_simp_tac" to split and simplify records added.
    87  
    88 * 'specification' command added, allowing for definition by
    89   specification.  There is also an 'ax_specification' command that
    90   introduces the new constants axiomatically.
    91 
    92 * arith(_tac) is now able to generate counterexamples for reals as well.
    93 
    94 * SET-Protocol: formalization and verification of the SET protocol suite;
    95 
    96 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
    97  defintions, thanks to Sava Krsti\'{c} and John Matthews.
    98 
    99 * Unions and Intersections:
   100   The x-symbol output syntax of UN and INT has been changed
   101   from "\<Union>x \<in> A. B" to "\<Union\<^bsub>x \<in> A\<^esub> B"
   102   i.e. the index formulae has become a subscript, like in normal math.
   103   Similarly for "\<Union>x. B", and for \<Inter> instead of \<Union>.
   104   The subscript version is also accepted as input syntax.
   105 
   106 
   107 New in Isabelle2003 (May 2003)
   108 --------------------------------
   109 
   110 *** General ***
   111 
   112 * Provers/simplifier:
   113 
   114   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   115     Assumptions are now subject to complete mutual simplification,
   116     not just from left to right. The simplifier now preserves
   117     the order of assumptions.
   118 
   119     Potential INCOMPATIBILITY:
   120 
   121     -- simp sometimes diverges where the old version did
   122        not, e.g. invoking simp on the goal
   123 
   124         [| P (f x); y = x; f x = f y |] ==> Q
   125 
   126        now gives rise to the infinite reduction sequence
   127 
   128         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   129 
   130        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   131        kind of problem.
   132 
   133     -- Tactics combining classical reasoner and simplification (such as auto)
   134        are also affected by this change, because many of them rely on
   135        simp. They may sometimes diverge as well or yield a different numbers
   136        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   137        in case of problems. Sometimes subsequent calls to the classical
   138        reasoner will fail because a preceeding call to the simplifier too
   139        eagerly simplified the goal, e.g. deleted redundant premises.
   140 
   141   - The simplifier trace now shows the names of the applied rewrite rules
   142 
   143   - You can limit the number of recursive invocations of the simplifier
   144     during conditional rewriting (where the simplifie tries to solve the
   145     conditions before applying the rewrite rule):
   146     ML "simp_depth_limit := n"
   147     where n is an integer. Thus you can force termination where previously
   148     the simplifier would diverge.
   149 
   150   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   151 
   152   - No longer aborts on failed congruence proof.  Instead, the
   153     congruence is ignored.
   154 
   155 * Pure: New generic framework for extracting programs from constructive
   156   proofs. See HOL/Extraction.thy for an example instantiation, as well
   157   as HOL/Extraction for some case studies.
   158 
   159 * Pure: The main goal of the proof state is no longer shown by default, only
   160 the subgoals. This behaviour is controlled by a new flag.
   161    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   162 (ML: Proof.show_main_goal).
   163 
   164 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   165 rules whose conclusion matches subgoal 1:
   166       PG menu: Isabelle/Isar -> Show me -> matching rules
   167 The rules are ordered by how closely they match the subgoal.
   168 In particular, rules that solve a subgoal outright are displayed first
   169 (or rather last, the way they are printed).
   170 (ML: ProofGeneral.print_intros())
   171 
   172 * Pure: New flag trace_unify_fail causes unification to print
   173 diagnostic information (PG: in trace buffer) when it fails. This is
   174 useful for figuring out why single step proofs like rule, erule or
   175 assumption failed.
   176 
   177 * Pure: Locale specifications now produce predicate definitions
   178 according to the body of text (covering assumptions modulo local
   179 definitions); predicate "loc_axioms" covers newly introduced text,
   180 while "loc" is cumulative wrt. all included locale expressions; the
   181 latter view is presented only on export into the global theory
   182 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   183 on the old view without predicates;
   184 
   185 * Pure: predefined locales "var" and "struct" are useful for sharing
   186 parameters (as in CASL, for example); just specify something like
   187 ``var x + var y + struct M'' as import;
   188 
   189 * Pure: improved thms_containing: proper indexing of facts instead of
   190 raw theorems; check validity of results wrt. current name space;
   191 include local facts of proof configuration (also covers active
   192 locales), cover fixed variables in index; may use "_" in term
   193 specification; an optional limit for the number of printed facts may
   194 be given (the default is 40);
   195 
   196 * Pure: disallow duplicate fact bindings within new-style theory files
   197 (batch-mode only);
   198 
   199 * Provers: improved induct method: assumptions introduced by case
   200 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   201 the goal statement); "foo" still refers to all facts collectively;
   202 
   203 * Provers: the function blast.overloaded has been removed: all constants
   204 are regarded as potentially overloaded, which improves robustness in exchange
   205 for slight decrease in efficiency;
   206 
   207 * Provers/linorder: New generic prover for transitivity reasoning over
   208 linear orders.  Note: this prover is not efficient!
   209 
   210 * Isar: preview of problems to finish 'show' now produce an error
   211 rather than just a warning (in interactive mode);
   212 
   213 
   214 *** HOL ***
   215 
   216 * arith(_tac)
   217 
   218  - Produces a counter example if it cannot prove a goal.
   219    Note that the counter example may be spurious if the goal is not a formula
   220    of quantifier-free linear arithmetic.
   221    In ProofGeneral the counter example appears in the trace buffer.
   222 
   223  - Knows about div k and mod k where k is a numeral of type nat or int.
   224 
   225  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   226    linear arithmetic fails. This takes account of quantifiers and divisibility.
   227    Presburger arithmetic can also be called explicitly via presburger(_tac). 
   228 
   229 * simp's arithmetic capabilities have been enhanced a bit: it now
   230 takes ~= in premises into account (by performing a case split);
   231 
   232 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   233 are distributed over a sum of terms;
   234 
   235 * New tactic "trans_tac" and method "trans" instantiate
   236 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   237 "<=", "<" and "="). 
   238 
   239 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main 
   240 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   241 
   242 * 'typedef' command has new option "open" to suppress the set
   243 definition;
   244 
   245 * functions Min and Max on finite sets have been introduced (theory
   246 Finite_Set);
   247 
   248 * attribute [symmetric] now works for relations as well; it turns
   249 (x,y) : R^-1 into (y,x) : R, and vice versa;
   250 
   251 * induct over a !!-quantified statement (say !!x1..xn):
   252   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   253 
   254 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   255 %x. None. Warning: empty_def now refers to the previously hidden definition
   256 of the empty set.
   257 
   258 * Algebra: formalization of classical algebra.  Intended as base for
   259 any algebraic development in Isabelle.  Currently covers group theory
   260 (up to Sylow's theorem) and ring theory (Universal Property of
   261 Univariate Polynomials).  Contributions welcome;
   262 
   263 * GroupTheory: deleted, since its material has been moved to Algebra;
   264 
   265 * Complex: new directory of the complex numbers with numeric constants, 
   266 nonstandard complex numbers, and some complex analysis, standard and 
   267 nonstandard (Jacques Fleuriot);
   268 
   269 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   270 
   271 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques 
   272 Fleuriot);
   273 
   274 * Real/HahnBanach: updated and adapted to locales;
   275 
   276 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   277 Gray and Kramer);
   278 
   279 * UNITY: added the Meier-Sanders theory of progress sets;
   280 
   281 * MicroJava: bytecode verifier and lightweight bytecode verifier
   282 as abstract algorithms, instantiated to the JVM;
   283 
   284 * Bali: Java source language formalization. Type system, operational
   285 semantics, axiomatic semantics. Supported language features:
   286 classes, interfaces, objects,virtual methods, static methods,
   287 static/instance fields, arrays, access modifiers, definite
   288 assignment, exceptions.
   289 
   290 
   291 *** ZF ***
   292 
   293 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   294 universe, etc.);
   295 
   296 * Main ZF: virtually all theories converted to new-style format;
   297 
   298 
   299 *** ML ***
   300 
   301 * Pure: Tactic.prove provides sane interface for internal proofs;
   302 omits the infamous "standard" operation, so this is more appropriate
   303 than prove_goalw_cterm in many situations (e.g. in simprocs);
   304 
   305 * Pure: improved error reporting of simprocs;
   306 
   307 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   308 up simprocs;
   309 
   310 
   311 *** Document preparation ***
   312 
   313 * uses \par instead of \\ for line breaks in theory text. This may
   314 shift some page breaks in large documents. To get the old behaviour
   315 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   316 
   317 * minimized dependencies of isabelle.sty and isabellesym.sty on 
   318 other packages
   319 
   320 * \<euro> now needs package babel/greek instead of marvosym (which
   321 broke \Rightarrow)
   322 
   323 * normal size for \<zero>...\<nine> (uses \mathbf instead of 
   324 textcomp package)
   325 
   326 
   327 New in Isabelle2002 (March 2002)
   328 --------------------------------
   329 
   330 *** Document preparation ***
   331 
   332 * greatly simplified document preparation setup, including more
   333 graceful interpretation of isatool usedir -i/-d/-D options, and more
   334 instructive isatool mkdir; users should basically be able to get
   335 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   336 users may run a separate document processing stage manually like this:
   337 "isatool usedir -D output HOL Test && isatool document Test/output";
   338 
   339 * theory dependency graph may now be incorporated into documents;
   340 isatool usedir -g true will produce session_graph.eps/.pdf for use
   341 with \includegraphics of LaTeX;
   342 
   343 * proper spacing of consecutive markup elements, especially text
   344 blocks after section headings;
   345 
   346 * support bold style (for single symbols only), input syntax is like
   347 this: "\<^bold>\<alpha>" or "\<^bold>A";
   348 
   349 * \<bullet> is now output as bold \cdot by default, which looks much
   350 better in printed text;
   351 
   352 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   353 note that these symbols are currently unavailable in Proof General /
   354 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   355 
   356 * isatool latex no longer depends on changed TEXINPUTS, instead
   357 isatool document copies the Isabelle style files to the target
   358 location;
   359 
   360 
   361 *** Isar ***
   362 
   363 * Pure/Provers: improved proof by cases and induction;
   364   - 'case' command admits impromptu naming of parameters (such as
   365     "case (Suc n)");
   366   - 'induct' method divinates rule instantiation from the inductive
   367     claim; no longer requires excessive ?P bindings for proper
   368     instantiation of cases;
   369   - 'induct' method properly enumerates all possibilities of set/type
   370     rules; as a consequence facts may be also passed through *type*
   371     rules without further ado;
   372   - 'induct' method now derives symbolic cases from the *rulified*
   373     rule (before it used to rulify cases stemming from the internal
   374     atomized version); this means that the context of a non-atomic
   375     statement becomes is included in the hypothesis, avoiding the
   376     slightly cumbersome show "PROP ?case" form;
   377   - 'induct' may now use elim-style induction rules without chaining
   378     facts, using ``missing'' premises from the goal state; this allows
   379     rules stemming from inductive sets to be applied in unstructured
   380     scripts, while still benefitting from proper handling of non-atomic
   381     statements; NB: major inductive premises need to be put first, all
   382     the rest of the goal is passed through the induction;
   383   - 'induct' proper support for mutual induction involving non-atomic
   384     rule statements (uses the new concept of simultaneous goals, see
   385     below);
   386   - append all possible rule selections, but only use the first
   387     success (no backtracking);
   388   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   389   - undeclared rule case names default to numbers 1, 2, 3, ...;
   390   - added 'print_induct_rules' (covered by help item in recent Proof
   391     General versions);
   392   - moved induct/cases attributes to Pure, methods to Provers;
   393   - generic method setup instantiated for FOL and HOL;
   394 
   395 * Pure: support multiple simultaneous goal statements, for example
   396 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   397 meta-level mechanism, this acts as if several individual goals had
   398 been stated separately; in particular common proof methods need to be
   399 repeated in order to cover all claims; note that a single elimination
   400 step is *not* sufficient to establish the two conjunctions, so this
   401 fails:
   402 
   403   assume "A & B" then have A and B ..   (*".." fails*)
   404 
   405 better use "obtain" in situations as above; alternative refer to
   406 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   407 
   408 * Pure: proper integration with ``locales''; unlike the original
   409 version by Florian Kammüller, Isar locales package high-level proof
   410 contexts rather than raw logical ones (e.g. we admit to include
   411 attributes everywhere); operations on locales include merge and
   412 rename; support for implicit arguments (``structures''); simultaneous
   413 type-inference over imports and text; see also HOL/ex/Locales.thy for
   414 some examples;
   415 
   416 * Pure: the following commands have been ``localized'', supporting a
   417 target locale specification "(in name)": 'lemma', 'theorem',
   418 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   419 stored both within the locale and at the theory level (exported and
   420 qualified by the locale name);
   421 
   422 * Pure: theory goals may now be specified in ``long'' form, with
   423 ad-hoc contexts consisting of arbitrary locale elements. for example
   424 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   425 definitions may be given, too); the result is a meta-level rule with
   426 the context elements being discharged in the obvious way;
   427 
   428 * Pure: new proof command 'using' allows to augment currently used
   429 facts after a goal statement ('using' is syntactically analogous to
   430 'apply', but acts on the goal's facts only); this allows chained facts
   431 to be separated into parts given before and after a claim, as in
   432 ``from a and b have C using d and e <proof>'';
   433 
   434 * Pure: renamed "antecedent" case to "rule_context";
   435 
   436 * Pure: new 'judgment' command records explicit information about the
   437 object-logic embedding (used by several tools internally); no longer
   438 use hard-wired "Trueprop";
   439 
   440 * Pure: added 'corollary' command;
   441 
   442 * Pure: fixed 'token_translation' command;
   443 
   444 * Pure: removed obsolete 'exported' attribute;
   445 
   446 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   447 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   448 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   449 
   450 * Pure: method 'atomize' presents local goal premises as object-level
   451 statements (atomic meta-level propositions); setup controlled via
   452 rewrite rules declarations of 'atomize' attribute; example
   453 application: 'induct' method with proper rule statements in improper
   454 proof *scripts*;
   455 
   456 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   457 now consider the syntactic context of assumptions, giving a better
   458 chance to get type-inference of the arguments right (this is
   459 especially important for locales);
   460 
   461 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   462 mode;
   463 
   464 * Pure/obtain: the formal conclusion "thesis", being marked as
   465 ``internal'', may no longer be reference directly in the text;
   466 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   467 situations;
   468 
   469 * Pure: generic 'sym' attribute which declares a rule both as pure
   470 'elim?' and for the 'symmetric' operation;
   471 
   472 * Pure: marginal comments ``--'' may now occur just anywhere in the
   473 text; the fixed correlation with particular command syntax has been
   474 discontinued;
   475 
   476 * Pure: new method 'rules' is particularly well-suited for proof
   477 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   478 but often produces more compact proof terms with less detours;
   479 
   480 * Pure/Provers/classical: simplified integration with pure rule
   481 attributes and methods; the classical "intro?/elim?/dest?"
   482 declarations coincide with the pure ones; the "rule" method no longer
   483 includes classically swapped intros; "intro" and "elim" methods no
   484 longer pick rules from the context; also got rid of ML declarations
   485 AddXIs/AddXEs/AddXDs; all of this has some potential for
   486 INCOMPATIBILITY;
   487 
   488 * Provers/classical: attribute 'swapped' produces classical inversions
   489 of introduction rules;
   490 
   491 * Provers/simplifier: 'simplified' attribute may refer to explicit
   492 rules instead of full simplifier context; 'iff' attribute handles
   493 conditional rules;
   494 
   495 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   496 
   497 * HOL: 'recdef' now fails on unfinished automated proofs, use
   498 "(permissive)" option to recover old behavior;
   499 
   500 * HOL: 'inductive' no longer features separate (collective) attributes
   501 for 'intros' (was found too confusing);
   502 
   503 * HOL: properly declared induction rules less_induct and
   504 wf_induct_rule;
   505 
   506 
   507 *** HOL ***
   508 
   509 * HOL: moved over to sane numeral syntax; the new policy is as
   510 follows:
   511 
   512   - 0 and 1 are polymorphic constants, which are defined on any
   513   numeric type (nat, int, real etc.);
   514 
   515   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   516   binary representation internally;
   517 
   518   - type nat has special constructor Suc, and generally prefers Suc 0
   519   over 1::nat and Suc (Suc 0) over 2::nat;
   520 
   521 This change may cause significant problems of INCOMPATIBILITY; here
   522 are some hints on converting existing sources:
   523 
   524   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   525   entities, so expressions involving "-" (unary or binary minus) need
   526   to be spaced properly;
   527 
   528   - existing occurrences of "1" may need to be constraint "1::nat" or
   529   even replaced by Suc 0; similar for old "2";
   530 
   531   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   532 
   533   - remove all special provisions on numerals in proofs;
   534 
   535 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   536 representation (depends on bin_arith_simps in the default context);
   537 
   538 * HOL: symbolic syntax for x^2 (numeral 2);
   539 
   540 * HOL: the class of all HOL types is now called "type" rather than
   541 "term"; INCOMPATIBILITY, need to adapt references to this type class
   542 in axclass/classes, instance/arities, and (usually rare) occurrences
   543 in typings (of consts etc.); internally the class is called
   544 "HOL.type", ML programs should refer to HOLogic.typeS;
   545 
   546 * HOL/record package improvements:
   547   - new derived operations "fields" to build a partial record section,
   548     "extend" to promote a fixed record to a record scheme, and
   549     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   550     declared as simp by default;
   551   - shared operations ("more", "fields", etc.) now need to be always
   552     qualified) --- potential INCOMPATIBILITY;
   553   - removed "make_scheme" operations (use "make" with "extend") --
   554     INCOMPATIBILITY;
   555   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   556   - provides cases/induct rules for use with corresponding Isar
   557     methods (for concrete records, record schemes, concrete more
   558     parts, and schematic more parts -- in that order);
   559   - internal definitions directly based on a light-weight abstract
   560     theory of product types over typedef rather than datatype;
   561 
   562 * HOL: generic code generator for generating executable ML code from
   563 specifications; specific support for HOL constructs such as inductive
   564 datatypes and sets, as well as recursive functions; can be invoked
   565 via 'generate_code' theory section;
   566 
   567 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   568 
   569 * HOL: consolidated and renamed several theories.  In particular:
   570 	Ord.thy has been absorbed into HOL.thy
   571 	String.thy has been absorbed into List.thy
   572  
   573 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   574 (beware of argument permutation!);
   575 
   576 * HOL: linorder_less_split superseded by linorder_cases;
   577 
   578 * HOL/List: "nodups" renamed to "distinct";
   579 
   580 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   581 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   582   - Ex_def has changed, now need to use some_eq_ex
   583 
   584 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   585 in this (rare) case use:
   586 
   587   delSWrapper "split_all_tac"
   588   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   589 
   590 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   591 MAY FAIL;
   592 
   593 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   594 Isabelle's type classes, ^ on functions and relations has too general
   595 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   596 necessary to attach explicit type constraints;
   597 
   598 * HOL/Relation: the prefix name of the infix "O" has been changed from
   599 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   600 renamed accordingly (eg "compI" -> "rel_compI").
   601 
   602 * HOL: syntax translations now work properly with numerals and records
   603 expressions;
   604 
   605 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   606 of "lam" -- INCOMPATIBILITY;
   607 
   608 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   609 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   610 renamed "Product_Type.unit";
   611 
   612 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   613 
   614 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   615 the "cases" method);
   616 
   617 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   618 Florian Kammüller);
   619 
   620 * HOL/IMP: updated and converted to new-style theory format; several
   621 parts turned into readable document, with proper Isar proof texts and
   622 some explanations (by Gerwin Klein);
   623 
   624 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   625 
   626 * HOL-Hyperreal is now a logic image;
   627 
   628 
   629 *** HOLCF ***
   630 
   631 * Isar: consts/constdefs supports mixfix syntax for continuous
   632 operations;
   633 
   634 * Isar: domain package adapted to new-style theory format, e.g. see
   635 HOLCF/ex/Dnat.thy;
   636 
   637 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   638 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   639 lift.induct_tac, always use UU instead of Undef;
   640 
   641 * HOLCF/IMP: updated and converted to new-style theory;
   642 
   643 
   644 *** ZF ***
   645 
   646 * Isar: proper integration of logic-specific tools and packages,
   647 including theory commands '(co)inductive', '(co)datatype',
   648 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   649 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   650 
   651 * theory Main no longer includes AC; for the Axiom of Choice, base
   652 your theory on Main_ZFC;
   653 
   654 * the integer library now covers quotients and remainders, with many
   655 laws relating division to addition, multiplication, etc.;
   656 
   657 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   658 typeless version of the formalism;
   659 
   660 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   661 format;
   662 
   663 * ZF/Induct: new directory for examples of inductive definitions,
   664 including theory Multiset for multiset orderings; converted to
   665 new-style theory format;
   666 
   667 * ZF: many new theorems about lists, ordinals, etc.;
   668 
   669 
   670 *** General ***
   671 
   672 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   673 variable proof controls level of detail: 0 = no proofs (only oracle
   674 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   675 also ref manual for further ML interfaces;
   676 
   677 * Pure/axclass: removed obsolete ML interface
   678 goal_subclass/goal_arity;
   679 
   680 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   681 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   682 separate tokens, so expressions involving minus need to be spaced
   683 properly;
   684 
   685 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   686 rather than "infixl" or "infixr";
   687 
   688 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   689 sort constraint specifications in type inference; e.g. "x::_::foo"
   690 ensures that the type of "x" is of sort "foo" (but not necessarily a
   691 type variable);
   692 
   693 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   694 control output of nested => (types); the default behavior is
   695 "type_brackets";
   696 
   697 * Pure/syntax: builtin parse translation for "_constify" turns valued
   698 tokens into AST constants;
   699 
   700 * Pure/syntax: prefer later declarations of translations and print
   701 translation functions; potential INCOMPATIBILITY: need to reverse
   702 multiple declarations for same syntax element constant;
   703 
   704 * Pure/show_hyps reset by default (in accordance to existing Isar
   705 practice);
   706 
   707 * Provers/classical: renamed addaltern to addafter, addSaltern to
   708 addSafter;
   709 
   710 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   711 as well;
   712 
   713 * system: tested support for MacOS X; should be able to get Isabelle +
   714 Proof General to work in a plain Terminal after installing Poly/ML
   715 (e.g. from the Isabelle distribution area) and GNU bash alone
   716 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   717 support requires further installations, e.g. from
   718 http://fink.sourceforge.net/);
   719 
   720 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   721 
   722 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   723 of 40 MB), cf. ML_OPTIONS;
   724 
   725 * system: Proof General keywords specification is now part of the
   726 Isabelle distribution (see etc/isar-keywords.el);
   727 
   728 * system: support for persistent Proof General sessions (refrain from
   729 outdating all loaded theories on startup); user may create writable
   730 logic images like this: ``isabelle -q HOL Test'';
   731 
   732 * system: smart selection of Isabelle process versus Isabelle
   733 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   734 run both "isabelle" and "Isabelle" even if file names are badly
   735 damaged (executable inspects the case of the first letter of its own
   736 name); added separate "isabelle-process" and "isabelle-interface";
   737 
   738 * system: refrain from any attempt at filtering input streams; no
   739 longer support ``8bit'' encoding of old isabelle font, instead proper
   740 iso-latin characters may now be used; the related isatools
   741 "symbolinput" and "nonascii" have disappeared as well;
   742 
   743 * system: removed old "xterm" interface (the print modes "xterm" and
   744 "xterm_color" are still available for direct use in a suitable
   745 terminal);
   746 
   747 
   748 
   749 New in Isabelle99-2 (February 2001)
   750 -----------------------------------
   751 
   752 *** Overview of INCOMPATIBILITIES ***
   753 
   754 * HOL: please note that theories in the Library and elsewhere often use the
   755 new-style (Isar) format; to refer to their theorems in an ML script you must
   756 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   757 
   758 * HOL: inductive package no longer splits induction rule aggressively,
   759 but only as far as specified by the introductions given; the old
   760 format may be recovered via ML function complete_split_rule or attribute
   761 'split_rule (complete)';
   762 
   763 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   764 gfp_Tarski to gfp_unfold;
   765 
   766 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   767 
   768 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   769 relation); infix "^^" has been renamed "``"; infix "``" has been
   770 renamed "`"; "univalent" has been renamed "single_valued";
   771 
   772 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   773 operation;
   774 
   775 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   776 
   777 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   778 
   779 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   780 consequence, it is no longer monotonic wrt. the local goal context
   781 (which is now passed through the inductive cases);
   782 
   783 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   784 \<gg> to \<ggreater>;
   785 
   786 
   787 *** Document preparation ***
   788 
   789 * \isabellestyle{NAME} selects version of Isabelle output (currently
   790 available: are "it" for near math-mode best-style output, "sl" for
   791 slanted text style, and "tt" for plain type-writer; if no
   792 \isabellestyle command is given, output is according to slanted
   793 type-writer);
   794 
   795 * support sub/super scripts (for single symbols only), input syntax is
   796 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   797 
   798 * some more standard symbols; see Appendix A of the system manual for
   799 the complete list of symbols defined in isabellesym.sty;
   800 
   801 * improved isabelle style files; more abstract symbol implementation
   802 (should now use \isamath{...} and \isatext{...} in custom symbol
   803 definitions);
   804 
   805 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   806 state; Note that presentation of goal states does not conform to
   807 actual human-readable proof documents.  Please do not include goal
   808 states into document output unless you really know what you are doing!
   809 
   810 * proper indentation of antiquoted output with proportional LaTeX
   811 fonts;
   812 
   813 * no_document ML operator temporarily disables LaTeX document
   814 generation;
   815 
   816 * isatool unsymbolize tunes sources for plain ASCII communication;
   817 
   818 
   819 *** Isar ***
   820 
   821 * Pure: Isar now suffers initial goal statements to contain unbound
   822 schematic variables (this does not conform to actual readable proof
   823 documents, due to unpredictable outcome and non-compositional proof
   824 checking); users who know what they are doing may use schematic goals
   825 for Prolog-style synthesis of proven results;
   826 
   827 * Pure: assumption method (an implicit finishing) now handles actual
   828 rules as well;
   829 
   830 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   831 initial goal, declare "that" only as Pure intro (only for single
   832 steps); the "that" rule assumption may now be involved in implicit
   833 finishing, thus ".." becomes a feasible for trivial obtains;
   834 
   835 * Pure: default proof step now includes 'intro_classes'; thus trivial
   836 instance proofs may be performed by "..";
   837 
   838 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   839 statements as well;
   840 
   841 * Pure: more robust selection of calculational rules;
   842 
   843 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   844 rule (as well as the assumption rule);
   845 
   846 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   847 lemmas, using the graph browser tool;
   848 
   849 * Pure: predict failure of "show" in interactive mode;
   850 
   851 * Pure: 'thms_containing' now takes actual terms as arguments;
   852 
   853 * HOL: improved method 'induct' --- now handles non-atomic goals
   854 (potential INCOMPATIBILITY); tuned error handling;
   855 
   856 * HOL: cases and induct rules now provide explicit hints about the
   857 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   858 any remaining facts are inserted into the goal verbatim;
   859 
   860 * HOL: local contexts (aka cases) may now contain term bindings as
   861 well; the 'cases' and 'induct' methods new provide a ?case binding for
   862 the result to be shown in each case;
   863 
   864 * HOL: added 'recdef_tc' command;
   865 
   866 * isatool convert assists in eliminating legacy ML scripts;
   867 
   868 
   869 *** HOL ***
   870 
   871 * HOL/Library: a collection of generic theories to be used together
   872 with main HOL; the theory loader path already includes this directory
   873 by default; the following existing theories have been moved here:
   874 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   875 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   876 
   877 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   878 modelling and verification task performed in Isabelle/HOL +
   879 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   880 
   881 * HOL/Algebra: special summation operator SUM no longer exists, it has
   882 been replaced by setsum; infix 'assoc' now has priority 50 (like
   883 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   884 'domain', this makes the theory consistent with mathematical
   885 literature;
   886 
   887 * HOL basics: added overloaded operations "inverse" and "divide"
   888 (infix "/"), syntax for generic "abs" operation, generic summation
   889 operator \<Sum>;
   890 
   891 * HOL/typedef: simplified package, provide more useful rules (see also
   892 HOL/subset.thy);
   893 
   894 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   895 now expressed as a proper nested rule (old-style tactic scripts may
   896 require atomize_strip_tac to cope with non-atomic premises);
   897 
   898 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   899 to "split_conv" (old name still available for compatibility);
   900 
   901 * HOL: improved concrete syntax for strings (e.g. allows translation
   902 rules with string literals);
   903 
   904 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   905  and Fleuriot's mechanization of analysis, including the transcendental
   906  functions for the reals;
   907 
   908 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   909 
   910 
   911 *** CTT ***
   912 
   913 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   914 "lam" is displayed as TWO lambda-symbols
   915 
   916 * CTT: theory Main now available, containing everything (that is, Bool
   917 and Arith);
   918 
   919 
   920 *** General ***
   921 
   922 * Pure: the Simplifier has been implemented properly as a derived rule
   923 outside of the actual kernel (at last!); the overall performance
   924 penalty in practical applications is about 50%, while reliability of
   925 the Isabelle inference kernel has been greatly improved;
   926 
   927 * print modes "brackets" and "no_brackets" control output of nested =>
   928 (types) and ==> (props); the default behaviour is "brackets";
   929 
   930 * Provers: fast_tac (and friends) now handle actual object-logic rules
   931 as assumptions as well;
   932 
   933 * system: support Poly/ML 4.0;
   934 
   935 * system: isatool install handles KDE version 1 or 2;
   936 
   937 
   938 
   939 New in Isabelle99-1 (October 2000)
   940 ----------------------------------
   941 
   942 *** Overview of INCOMPATIBILITIES ***
   943 
   944 * HOL: simplification of natural numbers is much changed; to partly
   945 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   946 issue the following ML commands:
   947 
   948   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   949   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   950 
   951 * HOL: simplification no longer dives into case-expressions; this is
   952 controlled by "t.weak_case_cong" for each datatype t;
   953 
   954 * HOL: nat_less_induct renamed to less_induct;
   955 
   956 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   957 fixsome to patch .thy and .ML sources automatically;
   958 
   959   select_equality  -> some_equality
   960   select_eq_Ex     -> some_eq_ex
   961   selectI2EX       -> someI2_ex
   962   selectI2         -> someI2
   963   selectI          -> someI
   964   select1_equality -> some1_equality
   965   Eps_sym_eq       -> some_sym_eq_trivial
   966   Eps_eq           -> some_eq_trivial
   967 
   968 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   969 
   970 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   971 instead);
   972 
   973 * HOL: the recursion equations generated by 'recdef' are now called
   974 f.simps instead of f.rules;
   975 
   976 * HOL: qed_spec_mp now also handles bounded ALL as well;
   977 
   978 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   979 sometimes be needed;
   980 
   981 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   982 
   983 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   984 
   985 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   986 product is now "<*>" instead of "Times"; the lexicographic product is
   987 now "<*lex*>" instead of "**";
   988 
   989 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   990 of main HOL, but was unused); better use HOL's datatype package;
   991 
   992 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   993 the old syntax may be recovered as follows:
   994 
   995   syntax (symbols)
   996     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   997       (infixl "\\<oplus>" 100)
   998 
   999 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1000 
  1001 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1002 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1003 internally;
  1004 
  1005 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1006 changed from A/r to A//r;
  1007 
  1008 * ZF: new treatment of arithmetic (nat & int) may break some old
  1009 proofs;
  1010 
  1011 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1012 rulify -> rule_format, elimify -> elim_format, ...);
  1013 
  1014 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1015 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1016 should have to change intro!! to intro? only); replaced "delrule" by
  1017 "rule del";
  1018 
  1019 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1020 
  1021 * Provers: strengthened force_tac by using new first_best_tac;
  1022 
  1023 * LaTeX document preparation: several changes of isabelle.sty (see
  1024 lib/texinputs);
  1025 
  1026 
  1027 *** Document preparation ***
  1028 
  1029 * formal comments (text blocks etc.) in new-style theories may now
  1030 contain antiquotations of thm/prop/term/typ/text to be presented
  1031 according to latex print mode; concrete syntax is like this:
  1032 @{term[show_types] "f(x) = a + x"};
  1033 
  1034 * isatool mkdir provides easy setup of Isabelle session directories,
  1035 including proper document sources;
  1036 
  1037 * generated LaTeX sources are now deleted after successful run
  1038 (isatool document -c); may retain a copy somewhere else via -D option
  1039 of isatool usedir;
  1040 
  1041 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1042 style files, achieving self-contained LaTeX sources and simplifying
  1043 LaTeX debugging;
  1044 
  1045 * old-style theories now produce (crude) LaTeX output as well;
  1046 
  1047 * browser info session directories are now self-contained (may be put
  1048 on WWW server seperately); improved graphs of nested sessions; removed
  1049 graph for 'all sessions';
  1050 
  1051 * several improvements in isabelle style files; \isabellestyle{it}
  1052 produces fake math mode output; \isamarkupheader is now \section by
  1053 default; see lib/texinputs/isabelle.sty etc.;
  1054 
  1055 
  1056 *** Isar ***
  1057 
  1058 * Isar/Pure: local results and corresponding term bindings are now
  1059 subject to Hindley-Milner polymorphism (similar to ML); this
  1060 accommodates incremental type-inference very nicely;
  1061 
  1062 * Isar/Pure: new derived language element 'obtain' supports
  1063 generalized existence reasoning;
  1064 
  1065 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1066 support accumulation of results, without applying any rules yet;
  1067 useful to collect intermediate results without explicit name
  1068 references, and for use with transitivity rules with more than 2
  1069 premises;
  1070 
  1071 * Isar/Pure: scalable support for case-analysis type proofs: new
  1072 'case' language element refers to local contexts symbolically, as
  1073 produced by certain proof methods; internally, case names are attached
  1074 to theorems as "tags";
  1075 
  1076 * Isar/Pure: theory command 'hide' removes declarations from
  1077 class/type/const name spaces;
  1078 
  1079 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1080 indicate potential overloading;
  1081 
  1082 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1083 
  1084 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1085 "{a,b,c}" instead of {a,b,c};
  1086 
  1087 * Isar/Pure now provides its own version of intro/elim/dest
  1088 attributes; useful for building new logics, but beware of confusion
  1089 with the version in Provers/classical;
  1090 
  1091 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1092 case name 'antecedent';
  1093 
  1094 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1095 to the current context is now done automatically);
  1096 
  1097 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1098 for definining proof methods in ML;
  1099 
  1100 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1101 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1102 most cases, one should have to change intro!! to intro? only);
  1103 replaced "delrule" by "rule del";
  1104 
  1105 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1106 'symmetric' attribute (the latter supercedes [RS sym]);
  1107 
  1108 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1109 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1110 well (including splits);
  1111 
  1112 * Isar/Provers: Simplifier and Classical methods now support all kind
  1113 of modifiers used in the past, including 'cong', 'iff', etc.
  1114 
  1115 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1116 of Simplifier and Classical reasoner);
  1117 
  1118 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1119 now support named cases; major packages (inductive, datatype, primrec,
  1120 recdef) support case names and properly name parameters;
  1121 
  1122 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1123 monotonicity conditions are extracted to be proven at end of
  1124 calculations;
  1125 
  1126 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1127 method anyway;
  1128 
  1129 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1130 split_if split_if_asm; datatype package provides theorems foo.splits =
  1131 foo.split foo.split_asm for each datatype;
  1132 
  1133 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1134 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1135 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1136 use "(cases (simplified))" method in proper proof texts);
  1137 
  1138 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1139 
  1140 * Isar: names of theorems etc. may be natural numbers as well;
  1141 
  1142 * Isar: 'pr' command: optional arguments for goals_limit and
  1143 ProofContext.prems_limit; no longer prints theory contexts, but only
  1144 proof states;
  1145 
  1146 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1147 additional print modes to be specified; e.g. "pr(latex)" will print
  1148 proof state according to the Isabelle LaTeX style;
  1149 
  1150 * Isar: improved support for emulating tactic scripts, including proof
  1151 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1152 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1153 (for HOL datatypes);
  1154 
  1155 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1156 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1157 'proof method scripts' have to be in depth-first order;
  1158 
  1159 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1160 
  1161 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1162 should instead use individual commands for printing items
  1163 (print_commands, print_methods etc.);
  1164 
  1165 * Isar: added 'nothing' --- the empty list of theorems;
  1166 
  1167 
  1168 *** HOL ***
  1169 
  1170 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1171 corresponding virtual machine and a specification of its bytecode
  1172 verifier and a lightweight bytecode verifier, including proofs of
  1173 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1174 Cornelia Pusch (see also the homepage of project Bali at
  1175 http://isabelle.in.tum.de/Bali/);
  1176 
  1177 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1178 Clemens Ballarin;
  1179 
  1180 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1181 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1182 Rasmussen;
  1183 
  1184 * HOL/Lattice: fundamental concepts of lattice theory and order
  1185 structures, including duals, properties of bounds versus algebraic
  1186 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1187 Theorem for complete lattices etc.; may also serve as a demonstration
  1188 for abstract algebraic reasoning using axiomatic type classes, and
  1189 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1190 
  1191 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1192 von Oheimb;
  1193 
  1194 * HOL/IMPP: extension of IMP with local variables and mutually
  1195 recursive procedures, by David von Oheimb;
  1196 
  1197 * HOL/Lambda: converted into new-style theory and document;
  1198 
  1199 * HOL/ex/Multiquote: example of multiple nested quotations and
  1200 anti-quotations -- basically a generalized version of de-Bruijn
  1201 representation; very useful in avoiding lifting of operations;
  1202 
  1203 * HOL/record: added general record equality rule to simpset; fixed
  1204 select-update simplification procedure to handle extended records as
  1205 well; admit "r" as field name;
  1206 
  1207 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1208 other numeric types and also as the identity of groups, rings, etc.;
  1209 
  1210 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1211 Types nat and int belong to this axclass;
  1212 
  1213 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1214    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1215    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1216   two terms #m*u and #n*u are replaced by #(m+n)*u
  1217     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1218   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1219     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1220 
  1221 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1222 powerful prover for predicate logic but knows nothing of clasets; see
  1223 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1224 
  1225 * HOL: new version of "case_tac" subsumes both boolean case split and
  1226 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1227 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1228 
  1229 * HOL: simplification no longer dives into case-expressions: only the
  1230 selector expression is simplified, but not the remaining arms; to
  1231 enable full simplification of case-expressions for datatype t, you may
  1232 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1233 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1234 
  1235 * HOL/recdef: the recursion equations generated by 'recdef' for
  1236 function 'f' are now called f.simps instead of f.rules; if all
  1237 termination conditions are proved automatically, these simplification
  1238 rules are added to the simpset, as in primrec; rules may be named
  1239 individually as well, resulting in a separate list of theorems for
  1240 each equation;
  1241 
  1242 * HOL/While is a new theory that provides a while-combinator. It
  1243 permits the definition of tail-recursive functions without the
  1244 provision of a termination measure. The latter is necessary once the
  1245 invariant proof rule for while is applied.
  1246 
  1247 * HOL: new (overloaded) notation for the set of elements below/above
  1248 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1249 
  1250 * HOL: theorems impI, allI, ballI bound as "strip";
  1251 
  1252 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1253 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1254 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1255 
  1256 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1257 
  1258 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1259 main HOL, but was unused);
  1260 
  1261 * HOL: fewer consts declared as global (e.g. have to refer to
  1262 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1263 
  1264 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1265 in case of overlap with user translations (e.g. judgements over
  1266 tuples); (note that the underlying logical represenation is still
  1267 bogus);
  1268 
  1269 
  1270 *** ZF ***
  1271 
  1272 * ZF: simplification automatically cancels common terms in arithmetic
  1273 expressions over nat and int;
  1274 
  1275 * ZF: new treatment of nat to minimize type-checking: all operators
  1276 coerce their operands to a natural number using the function natify,
  1277 making the algebraic laws unconditional;
  1278 
  1279 * ZF: as above, for int: operators coerce their operands to an integer
  1280 using the function intify;
  1281 
  1282 * ZF: the integer library now contains many of the usual laws for the
  1283 orderings, including $<=, and monotonicity laws for $+ and $*;
  1284 
  1285 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1286 simplification;
  1287 
  1288 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1289 to the simplifier and classical reasoner simultaneously;
  1290 
  1291 
  1292 *** General ***
  1293 
  1294 * Provers: blast_tac now handles actual object-logic rules as
  1295 assumptions; note that auto_tac uses blast_tac internally as well;
  1296 
  1297 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1298 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1299 
  1300 * Provers: delrules now handles destruct rules as well (no longer need
  1301 explicit make_elim);
  1302 
  1303 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1304   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1305 use instead the strong form,
  1306   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1307 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1308 from destruct-rules;
  1309 
  1310 * Provers: Simplifier.easy_setup provides a fast path to basic
  1311 Simplifier setup for new object-logics;
  1312 
  1313 * Pure: AST translation rules no longer require constant head on LHS;
  1314 
  1315 * Pure: improved name spaces: ambiguous output is qualified; support
  1316 for hiding of names;
  1317 
  1318 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1319 XSYMBOL_HOME; no longer need to do manual configuration in most
  1320 situations;
  1321 
  1322 * system: compression of ML heaps images may now be controlled via -c
  1323 option of isabelle and isatool usedir (currently only observed by
  1324 Poly/ML);
  1325 
  1326 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1327 useful for remote X11);
  1328 
  1329 * system: provide TAGS file for Isabelle sources;
  1330 
  1331 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1332 order;
  1333 
  1334 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1335 timing flag supersedes proof_timing and Toplevel.trace;
  1336 
  1337 * ML: new combinators |>> and |>>> for incremental transformations
  1338 with secondary results (e.g. certain theory extensions):
  1339 
  1340 * ML: PureThy.add_defs gets additional argument to indicate potential
  1341 overloading (usually false);
  1342 
  1343 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1344 results;
  1345 
  1346 
  1347 
  1348 New in Isabelle99 (October 1999)
  1349 --------------------------------
  1350 
  1351 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1352 
  1353 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1354 are no longer simplified.  (This allows the simplifier to unfold recursive
  1355 functional programs.)  To restore the old behaviour, declare
  1356 
  1357     Delcongs [if_weak_cong];
  1358 
  1359 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1360 complement;
  1361 
  1362 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1363 
  1364 * HOL/datatype: mutual_induct_tac no longer exists --
  1365   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1366 
  1367 * HOL/typedef: fixed type inference for representing set; type
  1368 arguments now have to occur explicitly on the rhs as type constraints;
  1369 
  1370 * ZF: The con_defs part of an inductive definition may no longer refer
  1371 to constants declared in the same theory;
  1372 
  1373 * HOL, ZF: the function mk_cases, generated by the inductive
  1374 definition package, has lost an argument.  To simplify its result, it
  1375 uses the default simpset instead of a supplied list of theorems.
  1376 
  1377 * HOL/List: the constructors of type list are now Nil and Cons;
  1378 
  1379 * Simplifier: the type of the infix ML functions
  1380         setSSolver addSSolver setSolver addSolver
  1381 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1382 for packaging solvers. A solver is created via
  1383         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1384 where the string argument is only a comment.
  1385 
  1386 
  1387 *** Proof tools ***
  1388 
  1389 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1390 decision procedure for linear arithmetic. Currently it is used for
  1391 types `nat', `int', and `real' in HOL (see below); it can, should and
  1392 will be instantiated for other types and logics as well.
  1393 
  1394 * The simplifier now accepts rewrite rules with flexible heads, eg
  1395      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1396   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1397   matching.
  1398 
  1399 
  1400 *** General ***
  1401 
  1402 * New Isabelle/Isar subsystem provides an alternative to traditional
  1403 tactical theorem proving; together with the ProofGeneral/isar user
  1404 interface it offers an interactive environment for developing human
  1405 readable proof documents (Isar == Intelligible semi-automated
  1406 reasoning); for further information see isatool doc isar-ref,
  1407 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1408 
  1409 * improved and simplified presentation of theories: better HTML markup
  1410 (including colors), graph views in several sizes; isatool usedir now
  1411 provides a proper interface for user theories (via -P option); actual
  1412 document preparation based on (PDF)LaTeX is available as well (for
  1413 new-style theories only); see isatool doc system for more information;
  1414 
  1415 * native support for Proof General, both for classic Isabelle and
  1416 Isabelle/Isar;
  1417 
  1418 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1419 using the graph browser tool;
  1420 
  1421 * Isabelle manuals now also available as PDF;
  1422 
  1423 * theory loader rewritten from scratch (may not be fully
  1424 bug-compatible); old loadpath variable has been replaced by show_path,
  1425 add_path, del_path, reset_path functions; new operations such as
  1426 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1427 isatool doc ref);
  1428 
  1429 * improved isatool install: option -k creates KDE application icon,
  1430 option -p DIR installs standalone binaries;
  1431 
  1432 * added ML_PLATFORM setting (useful for cross-platform installations);
  1433 more robust handling of platform specific ML images for SML/NJ;
  1434 
  1435 * the settings environment is now statically scoped, i.e. it is never
  1436 created again in sub-processes invoked from isabelle, isatool, or
  1437 Isabelle;
  1438 
  1439 * path element specification '~~' refers to '$ISABELLE_HOME';
  1440 
  1441 * in locales, the "assumes" and "defines" parts may be omitted if
  1442 empty;
  1443 
  1444 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1445 long arrows);
  1446 
  1447 * new print_mode "HTML";
  1448 
  1449 * new flag show_tags controls display of tags of theorems (which are
  1450 basically just comments that may be attached by some tools);
  1451 
  1452 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1453 mode and goal output format:
  1454 
  1455 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1456 244c244
  1457 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1458 ---
  1459 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1460 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1461 181c181
  1462 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1463 ---
  1464 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1465 
  1466 * function bind_thms stores lists of theorems (cf. bind_thm);
  1467 
  1468 * new shorthand tactics ftac, eatac, datac, fatac;
  1469 
  1470 * qed (and friends) now accept "" as result name; in that case the
  1471 theorem is not stored, but proper checks and presentation of the
  1472 result still apply;
  1473 
  1474 * theorem database now also indexes constants "Trueprop", "all",
  1475 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1476 
  1477 
  1478 *** HOL ***
  1479 
  1480 ** HOL arithmetic **
  1481 
  1482 * There are now decision procedures for linear arithmetic over nat and
  1483 int:
  1484 
  1485 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1486 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1487 are treated as atomic; subformulae not involving type `nat' or `int'
  1488 are ignored; quantified subformulae are ignored unless they are
  1489 positive universal or negative existential. The tactic has to be
  1490 invoked by hand and can be a little bit slow. In particular, the
  1491 running time is exponential in the number of occurrences of `min' and
  1492 `max', and `-' on `nat'.
  1493 
  1494 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1495 (negated) (in)equalities among the premises and the conclusion into
  1496 account (i.e. no compound formulae) and does not know about `min' and
  1497 `max', and `-' on `nat'. It is fast and is used automatically by the
  1498 simplifier.
  1499 
  1500 NB: At the moment, these decision procedures do not cope with mixed
  1501 nat/int formulae where the two parts interact, such as `m < n ==>
  1502 int(m) < int(n)'.
  1503 
  1504 * HOL/Numeral provides a generic theory of numerals (encoded
  1505 efficiently as bit strings); setup for types nat/int/real is in place;
  1506 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1507 int, existing theories and proof scripts may require a few additional
  1508 type constraints;
  1509 
  1510 * integer division and remainder can now be performed on constant
  1511 arguments;
  1512 
  1513 * many properties of integer multiplication, division and remainder
  1514 are now available;
  1515 
  1516 * An interface to the Stanford Validity Checker (SVC) is available through the
  1517 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1518 are proved automatically.  SVC must be installed separately, and its results
  1519 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1520 invocation of the underlying oracle).  For SVC see
  1521   http://verify.stanford.edu/SVC
  1522 
  1523 * IsaMakefile: the HOL-Real target now builds an actual image;
  1524 
  1525 
  1526 ** HOL misc **
  1527 
  1528 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1529 (in Isabelle/Isar) -- by Gertrud Bauer;
  1530 
  1531 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1532 analysis for assembly languages with subtypes;
  1533 
  1534 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1535 -- avoids syntactic ambiguities and treats state, transition, and
  1536 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1537 changed syntax and (many) tactics;
  1538 
  1539 * HOL/inductive: Now also handles more general introduction rules such
  1540   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1541   theorems are now maintained within the theory (maintained via the
  1542   "mono" attribute);
  1543 
  1544 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1545   (using function types) such as
  1546 
  1547   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1548 
  1549 * HOL/record: record_simproc (part of the default simpset) takes care
  1550 of selectors applied to updated records; record_split_tac is no longer
  1551 part of the default claset; update_defs may now be removed from the
  1552 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1553 
  1554   claset_ref () := claset() addSWrapper record_split_wrapper;
  1555   Delsimprocs [record_simproc]
  1556 
  1557 * HOL/typedef: fixed type inference for representing set; type
  1558 arguments now have to occur explicitly on the rhs as type constraints;
  1559 
  1560 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1561 names rather than an ML expression;
  1562 
  1563 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1564 supplied later.  Program schemes can be defined, such as
  1565     "While B C s = (if B s then While B C (C s) else s)"
  1566 where the well-founded relation can be chosen after B and C have been given.
  1567 
  1568 * HOL/List: the constructors of type list are now Nil and Cons;
  1569 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1570 course, ML tools referring to List.list.op # etc. have to be adapted;
  1571 
  1572 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1573 disabled by default; run isabelle with option -m HOL to get back to
  1574 the original Gordon/HOL-style output;
  1575 
  1576 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1577 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1578 
  1579 * HOL basic syntax simplified (more orthogonal): all variants of
  1580 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1581 Eps operator is provided as well: "SOME x. P[x]";
  1582 
  1583 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1584 
  1585 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1586 thus available for user theories;
  1587 
  1588 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1589 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1590 time;
  1591 
  1592 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1593 several times and then mp;
  1594 
  1595 
  1596 *** LK ***
  1597 
  1598 * the notation <<...>> is now available as a notation for sequences of
  1599 formulas;
  1600 
  1601 * the simplifier is now installed
  1602 
  1603 * the axiom system has been generalized (thanks to Soren Heilmann)
  1604 
  1605 * the classical reasoner now has a default rule database
  1606 
  1607 
  1608 *** ZF ***
  1609 
  1610 * new primrec section allows primitive recursive functions to be given
  1611 directly (as in HOL) over datatypes and the natural numbers;
  1612 
  1613 * new tactics induct_tac and exhaust_tac for induction (or case
  1614 analysis) over datatypes and the natural numbers;
  1615 
  1616 * the datatype declaration of type T now defines the recursor T_rec;
  1617 
  1618 * simplification automatically does freeness reasoning for datatype
  1619 constructors;
  1620 
  1621 * automatic type-inference, with AddTCs command to insert new
  1622 type-checking rules;
  1623 
  1624 * datatype introduction rules are now added as Safe Introduction rules
  1625 to the claset;
  1626 
  1627 * the syntax "if P then x else y" is now available in addition to
  1628 if(P,x,y);
  1629 
  1630 
  1631 *** Internal programming interfaces ***
  1632 
  1633 * tuned simplifier trace output; new flag debug_simp;
  1634 
  1635 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1636 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1637 
  1638 * AxClass.axclass_tac lost the theory argument;
  1639 
  1640 * tuned current_goals_markers semantics: begin / end goal avoids
  1641 printing empty lines;
  1642 
  1643 * removed prs and prs_fn hook, which was broken because it did not
  1644 include \n in its semantics, forcing writeln to add one
  1645 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1646 string -> unit if you really want to output text without newline;
  1647 
  1648 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1649 plain output, interface builders may have to enable 'isabelle_font'
  1650 mode to get Isabelle font glyphs as before;
  1651 
  1652 * refined token_translation interface; INCOMPATIBILITY: output length
  1653 now of type real instead of int;
  1654 
  1655 * theory loader actions may be traced via new ThyInfo.add_hook
  1656 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1657 your own database of information attached to *whole* theories -- as
  1658 opposed to intra-theory data slots offered via TheoryDataFun;
  1659 
  1660 * proper handling of dangling sort hypotheses (at last!);
  1661 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1662 extra sort hypotheses that can be witnessed from the type signature;
  1663 the force_strip_shyps flag is gone, any remaining shyps are simply
  1664 left in the theorem (with a warning issued by strip_shyps_warning);
  1665 
  1666 
  1667 
  1668 New in Isabelle98-1 (October 1998)
  1669 ----------------------------------
  1670 
  1671 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1672 
  1673 * several changes of automated proof tools;
  1674 
  1675 * HOL: major changes to the inductive and datatype packages, including
  1676 some minor incompatibilities of theory syntax;
  1677 
  1678 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1679 called `inj_on';
  1680 
  1681 * HOL: removed duplicate thms in Arith:
  1682   less_imp_add_less  should be replaced by  trans_less_add1
  1683   le_imp_add_le      should be replaced by  trans_le_add1
  1684 
  1685 * HOL: unary minus is now overloaded (new type constraints may be
  1686 required);
  1687 
  1688 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1689 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1690 now taken as an integer constant.
  1691 
  1692 * Pure: ML function 'theory_of' renamed to 'theory';
  1693 
  1694 
  1695 *** Proof tools ***
  1696 
  1697 * Simplifier:
  1698   1. Asm_full_simp_tac is now more aggressive.
  1699      1. It will sometimes reorient premises if that increases their power to
  1700         simplify.
  1701      2. It does no longer proceed strictly from left to right but may also
  1702         rotate premises to achieve further simplification.
  1703      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1704      old Asm_full_simp_tac in that it does not rotate premises.
  1705   2. The simplifier now knows a little bit about nat-arithmetic.
  1706 
  1707 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1708 allows for selected deletion of wrappers, by introduction of names for
  1709 wrapper functionals.  This implies that addbefore, addSbefore,
  1710 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1711 and that adding two tactics with the same name overwrites the first
  1712 one (emitting a warning).
  1713   type wrapper = (int -> tactic) -> (int -> tactic)
  1714   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1715   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1716   delWrapper, delSWrapper: claset *  string            -> claset
  1717   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1718 
  1719 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1720 semantics; addbefore now affects only the unsafe part of step_tac
  1721 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1722 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1723 by Force_tac;
  1724 
  1725 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1726 compWrapper; added safe wrapper (and access functions for it);
  1727 
  1728 * HOL/split_all_tac is now much faster and fails if there is nothing
  1729 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1730 and the names of the automatically generated variables have changed.
  1731 split_all_tac has moved within claset() from unsafe wrappers to safe
  1732 wrappers, which means that !!-bound variables are split much more
  1733 aggressively, and safe_tac and clarify_tac now split such variables.
  1734 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1735 Note: the same holds for record_split_tac, which does the job of
  1736 split_all_tac for record fields.
  1737 
  1738 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1739 permanently to the default simpset using Addsplits just like
  1740 Addsimps. They can be removed via Delsplits just like
  1741 Delsimps. Lower-case versions are also available.
  1742 
  1743 * HOL/Simplifier: The rule split_if is now part of the default
  1744 simpset. This means that the simplifier will eliminate all occurrences
  1745 of if-then-else in the conclusion of a goal. To prevent this, you can
  1746 either remove split_if completely from the default simpset by
  1747 `Delsplits [split_if]' or remove it in a specific call of the
  1748 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1749 other case splitting rules to/from the default simpset: every datatype
  1750 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1751 t is the name of the datatype).
  1752 
  1753 * Classical reasoner / Simplifier combination: new force_tac (and
  1754 derivatives Force_tac, force) combines rewriting and classical
  1755 reasoning (and whatever other tools) similarly to auto_tac, but is
  1756 aimed to solve the given subgoal completely.
  1757 
  1758 
  1759 *** General ***
  1760 
  1761 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1762 and `goalw': the theory is no longer needed as an explicit argument -
  1763 the current theory context is used; assumptions are no longer returned
  1764 at the ML-level unless one of them starts with ==> or !!; it is
  1765 recommended to convert to these new commands using isatool fixgoal
  1766 (backup your sources first!);
  1767 
  1768 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1769 the current theory context, and 'theory' to lookup stored theories;
  1770 
  1771 * new theory section 'locale' for declaring constants, assumptions and
  1772 definitions that have local scope;
  1773 
  1774 * new theory section 'nonterminals' for purely syntactic types;
  1775 
  1776 * new theory section 'setup' for generic ML setup functions
  1777 (e.g. package initialization);
  1778 
  1779 * the distribution now includes Isabelle icons: see
  1780 lib/logo/isabelle-{small,tiny}.xpm;
  1781 
  1782 * isatool install - install binaries with absolute references to
  1783 ISABELLE_HOME/bin;
  1784 
  1785 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1786 
  1787 * print mode 'emacs' reserved for Isamode;
  1788 
  1789 * support multiple print (ast) translations per constant name;
  1790 
  1791 * theorems involving oracles are now printed with a suffixed [!];
  1792 
  1793 
  1794 *** HOL ***
  1795 
  1796 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1797 
  1798 * HOL/inductive package reorganized and improved: now supports mutual
  1799 definitions such as
  1800 
  1801   inductive EVEN ODD
  1802     intrs
  1803       null "0 : EVEN"
  1804       oddI "n : EVEN ==> Suc n : ODD"
  1805       evenI "n : ODD ==> Suc n : EVEN"
  1806 
  1807 new theorem list "elims" contains an elimination rule for each of the
  1808 recursive sets; inductive definitions now handle disjunctive premises
  1809 correctly (also ZF);
  1810 
  1811 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1812 "mutual_induct" no longer exists - the induction rule is always
  1813 contained in "induct";
  1814 
  1815 
  1816 * HOL/datatype package re-implemented and greatly improved: now
  1817 supports mutually recursive datatypes such as
  1818 
  1819   datatype
  1820     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1821             | SUM ('a aexp) ('a aexp)
  1822             | DIFF ('a aexp) ('a aexp)
  1823             | NUM 'a
  1824   and
  1825     'a bexp = LESS ('a aexp) ('a aexp)
  1826             | AND ('a bexp) ('a bexp)
  1827             | OR ('a bexp) ('a bexp)
  1828 
  1829 as well as indirectly recursive datatypes such as
  1830 
  1831   datatype
  1832     ('a, 'b) term = Var 'a
  1833                   | App 'b ((('a, 'b) term) list)
  1834 
  1835 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1836 induction on mutually / indirectly recursive datatypes.
  1837 
  1838 Primrec equations are now stored in theory and can be accessed via
  1839 <function_name>.simps.
  1840 
  1841 INCOMPATIBILITIES:
  1842 
  1843   - Theories using datatypes must now have theory Datatype as an
  1844     ancestor.
  1845   - The specific <typename>.induct_tac no longer exists - use the
  1846     generic induct_tac instead.
  1847   - natE has been renamed to nat.exhaust - use exhaust_tac
  1848     instead of res_inst_tac ... natE. Note that the variable
  1849     names in nat.exhaust differ from the names in natE, this
  1850     may cause some "fragile" proofs to fail.
  1851   - The theorems split_<typename>_case and split_<typename>_case_asm
  1852     have been renamed to <typename>.split and <typename>.split_asm.
  1853   - Since default sorts of type variables are now handled correctly,
  1854     some datatype definitions may have to be annotated with explicit
  1855     sort constraints.
  1856   - Primrec definitions no longer require function name and type
  1857     of recursive argument.
  1858 
  1859 Consider using isatool fixdatatype to adapt your theories and proof
  1860 scripts to the new package (backup your sources first!).
  1861 
  1862 
  1863 * HOL/record package: considerably improved implementation; now
  1864 includes concrete syntax for record types, terms, updates; theorems
  1865 for surjective pairing and splitting !!-bound record variables; proof
  1866 support is as follows:
  1867 
  1868   1) standard conversions (selectors or updates applied to record
  1869 constructor terms) are part of the standard simpset;
  1870 
  1871   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1872 made part of standard simpset and claset via addIffs;
  1873 
  1874   3) a tactic for record field splitting (record_split_tac) is part of
  1875 the standard claset (addSWrapper);
  1876 
  1877 To get a better idea about these rules you may retrieve them via
  1878 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1879 the name of your record type.
  1880 
  1881 The split tactic 3) conceptually simplifies by the following rule:
  1882 
  1883   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1884 
  1885 Thus any record variable that is bound by meta-all will automatically
  1886 blow up into some record constructor term, consequently the
  1887 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1888 solve record problems automatically.
  1889 
  1890 
  1891 * reorganized the main HOL image: HOL/Integ and String loaded by
  1892 default; theory Main includes everything;
  1893 
  1894 * automatic simplification of integer sums and comparisons, using cancellation;
  1895 
  1896 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1897 
  1898 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1899 
  1900 * many new identities for unions, intersections, set difference, etc.;
  1901 
  1902 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1903 called split_if, split_split, split_sum_case and split_nat_case (to go
  1904 with add/delsplits);
  1905 
  1906 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1907 (?x::unit) = (); this is made part of the default simpset, which COULD
  1908 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1909 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1910 unit_abs_eta_conv is added in order to counter the effect of
  1911 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1912 %u.f();
  1913 
  1914 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1915 makes more sense);
  1916 
  1917 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1918   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1919   disjointness reasoning but breaking a few old proofs.
  1920 
  1921 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1922 to 'converse' from 'inverse' (for compatibility with ZF and some
  1923 literature);
  1924 
  1925 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1926 the well-founded relation;
  1927 
  1928 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1929     Compl A.  The "Compl" syntax remains available as input syntax for this
  1930     release ONLY.
  1931 
  1932 * HOL/Update: new theory of function updates:
  1933     f(a:=b) == %x. if x=a then b else f x
  1934 may also be iterated as in f(a:=b,c:=d,...);
  1935 
  1936 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1937 
  1938 * HOL/List:
  1939   - new function list_update written xs[i:=v] that updates the i-th
  1940     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1941   - new function `upt' written [i..j(] which generates the list
  1942     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1943     bound write [i..j], which is a shorthand for [i..j+1(].
  1944   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1945 
  1946 * HOL/Arith:
  1947   - removed 'pred' (predecessor) function;
  1948   - generalized some theorems about n-1;
  1949   - many new laws about "div" and "mod";
  1950   - new laws about greatest common divisors (see theory ex/Primes);
  1951 
  1952 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1953 instead of "inverse";
  1954 
  1955 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1956   of the multiset ordering;
  1957 
  1958 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1959   (not included by default);
  1960 
  1961 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1962 
  1963 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1964   programs, i.e. different program variables may have different types.
  1965 
  1966 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1967   [previously, this check worked only if the rewrite rule was unconditional]
  1968   Now rew can involve either definitions or equalities (either == or =).
  1969 
  1970 
  1971 *** ZF ***
  1972 
  1973 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1974   only the theorems proved on ZF.ML;
  1975 
  1976 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1977   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1978   disjointness reasoning but breaking a few old proofs.
  1979 
  1980 * ZF/Update: new theory of function updates
  1981     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1982   may also be iterated as in f(a:=b,c:=d,...);
  1983 
  1984 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1985 
  1986 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1987   [previously, this check worked only if the rewrite rule was unconditional]
  1988   Now rew can involve either definitions or equalities (either == or =).
  1989 
  1990 * case_tac provided for compatibility with HOL
  1991     (like the old excluded_middle_tac, but with subgoals swapped)
  1992 
  1993 
  1994 *** Internal programming interfaces ***
  1995 
  1996 * Pure: several new basic modules made available for general use, see
  1997 also src/Pure/README;
  1998 
  1999 * improved the theory data mechanism to support encapsulation (data
  2000 kind name replaced by private Object.kind, acting as authorization
  2001 key); new type-safe user interface via functor TheoryDataFun; generic
  2002 print_data function becomes basically useless;
  2003 
  2004 * removed global_names compatibility flag -- all theory declarations
  2005 are qualified by default;
  2006 
  2007 * module Pure/Syntax now offers quote / antiquote translation
  2008 functions (useful for Hoare logic etc. with implicit dependencies);
  2009 see HOL/ex/Antiquote for an example use;
  2010 
  2011 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2012 cterm -> thm;
  2013 
  2014 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2015 subgoal;
  2016 
  2017 * Display.print_goals function moved to Locale.print_goals;
  2018 
  2019 * standard print function for goals supports current_goals_markers
  2020 variable for marking begin of proof, end of proof, start of goal; the
  2021 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2022 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2023 for example;
  2024 
  2025 
  2026 
  2027 New in Isabelle98 (January 1998)
  2028 --------------------------------
  2029 
  2030 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2031 
  2032 * changed lexical syntax of terms / types: dots made part of long
  2033 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2034 
  2035 * simpset (and claset) reference variable replaced by functions
  2036 simpset / simpset_ref;
  2037 
  2038 * no longer supports theory aliases (via merge) and non-trivial
  2039 implicit merge of thms' signatures;
  2040 
  2041 * most internal names of constants changed due to qualified names;
  2042 
  2043 * changed Pure/Sequence interface (see Pure/seq.ML);
  2044 
  2045 
  2046 *** General Changes ***
  2047 
  2048 * hierachically structured name spaces (for consts, types, axms, thms
  2049 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2050 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2051 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2052 long_names for fully qualified output names; NOTE: ML programs
  2053 (special tactics, packages etc.) referring to internal names may have
  2054 to be adapted to cope with fully qualified names; in case of severe
  2055 backward campatibility problems try setting 'global_names' at compile
  2056 time to have enrything declared within a flat name space; one may also
  2057 fine tune name declarations in theories via the 'global' and 'local'
  2058 section;
  2059 
  2060 * reimplemented the implicit simpset and claset using the new anytype
  2061 data filed in signatures; references simpset:simpset ref etc. are
  2062 replaced by functions simpset:unit->simpset and
  2063 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2064 to patch your ML files accordingly;
  2065 
  2066 * HTML output now includes theory graph data for display with Java
  2067 applet or isatool browser; data generated automatically via isatool
  2068 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2069 
  2070 * defs may now be conditional; improved rewrite_goals_tac to handle
  2071 conditional equations;
  2072 
  2073 * defs now admits additional type arguments, using TYPE('a) syntax;
  2074 
  2075 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2076 creates a new theory node; implicit merge of thms' signatures is
  2077 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2078 transfer:theory->thm->thm in (rare) cases;
  2079 
  2080 * improved handling of draft signatures / theories; draft thms (and
  2081 ctyps, cterms) are automatically promoted to real ones;
  2082 
  2083 * slightly changed interfaces for oracles: admit many per theory, named
  2084 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2085 
  2086 * print_goals: optional output of const types (set show_consts and
  2087 show_types);
  2088 
  2089 * improved output of warnings (###) and errors (***);
  2090 
  2091 * subgoal_tac displays a warning if the new subgoal has type variables;
  2092 
  2093 * removed old README and Makefiles;
  2094 
  2095 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2096 
  2097 * removed obsolete init_pps and init_database;
  2098 
  2099 * deleted the obsolete tactical STATE, which was declared by
  2100     fun STATE tacfun st = tacfun st st;
  2101 
  2102 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2103 (which abbreviates $HOME);
  2104 
  2105 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2106 use isatool fixseq to adapt your ML programs (this works for fully
  2107 qualified references to the Sequence structure only!);
  2108 
  2109 * use_thy no longer requires writable current directory; it always
  2110 reloads .ML *and* .thy file, if either one is out of date;
  2111 
  2112 
  2113 *** Classical Reasoner ***
  2114 
  2115 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2116 tactics that use classical reasoning to simplify a subgoal without
  2117 splitting it into several subgoals;
  2118 
  2119 * Safe_tac: like safe_tac but uses the default claset;
  2120 
  2121 
  2122 *** Simplifier ***
  2123 
  2124 * added simplification meta rules:
  2125     (asm_)(full_)simplify: simpset -> thm -> thm;
  2126 
  2127 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2128 logics (again);
  2129 
  2130 * added prems argument to simplification procedures;
  2131 
  2132 * HOL, FOL, ZF: added infix function `addsplits':
  2133   instead of `<simpset> setloop (split_tac <thms>)'
  2134   you can simply write `<simpset> addsplits <thms>'
  2135 
  2136 
  2137 *** Syntax ***
  2138 
  2139 * TYPE('a) syntax for type reflection terms;
  2140 
  2141 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2142 
  2143 * pretty printer: changed order of mixfix annotation preference (again!);
  2144 
  2145 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2146 
  2147 
  2148 *** HOL ***
  2149 
  2150 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2151   with `addloop' of the simplifier to faciliate case splitting in premises.
  2152 
  2153 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2154 
  2155 * HOL/Auth: new protocol proofs including some for the Internet
  2156   protocol TLS;
  2157 
  2158 * HOL/Map: new theory of `maps' a la VDM;
  2159 
  2160 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2161 cancelling out common nat summands from =, <, <= (in)equalities, or
  2162 differences; simplification procedures nat_cancel_factor for
  2163 cancelling common factor from =, <, <= (in)equalities over natural
  2164 sums; nat_cancel contains both kinds of procedures, it is installed by
  2165 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2166 
  2167 * HOL/simplifier: terms of the form
  2168   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2169   are rewritten to
  2170   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2171   and those of the form
  2172   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2173   are rewritten to
  2174   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2175 
  2176 * HOL/datatype
  2177   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2178 
  2179   P(t_case f1 ... fn x) =
  2180      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2181         ...
  2182        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2183      )
  2184 
  2185   and a theorem `split_t_case_asm' of the form
  2186 
  2187   P(t_case f1 ... fn x) =
  2188     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2189         ...
  2190        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2191      )
  2192   which can be added to a simpset via `addsplits'. The existing theorems
  2193   expand_list_case and expand_option_case have been renamed to
  2194   split_list_case and split_option_case.
  2195 
  2196 * HOL/Arithmetic:
  2197   - `pred n' is automatically converted to `n-1'.
  2198     Users are strongly encouraged not to use `pred' any longer,
  2199     because it will disappear altogether at some point.
  2200   - Users are strongly encouraged to write "0 < n" rather than
  2201     "n ~= 0". Theorems and proof tools have been modified towards this
  2202     `standard'.
  2203 
  2204 * HOL/Lists:
  2205   the function "set_of_list" has been renamed "set" (and its theorems too);
  2206   the function "nth" now takes its arguments in the reverse order and
  2207   has acquired the infix notation "!" as in "xs!n".
  2208 
  2209 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2210 
  2211 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2212   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2213 
  2214 * HOL/record: extensible records with schematic structural subtyping
  2215 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2216 still lacks various theorems and concrete record syntax;
  2217 
  2218 
  2219 *** HOLCF ***
  2220 
  2221 * removed "axioms" and "generated by" sections;
  2222 
  2223 * replaced "ops" section by extended "consts" section, which is capable of
  2224   handling the continuous function space "->" directly;
  2225 
  2226 * domain package:
  2227   . proves theorems immediately and stores them in the theory,
  2228   . creates hierachical name space,
  2229   . now uses normal mixfix annotations (instead of cinfix...),
  2230   . minor changes to some names and values (for consistency),
  2231   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2232   . separator between mutual domain defs: changed "," to "and",
  2233   . improved handling of sort constraints;  now they have to
  2234     appear on the left-hand side of the equations only;
  2235 
  2236 * fixed LAM <x,y,zs>.b syntax;
  2237 
  2238 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2239 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2240 
  2241 
  2242 *** FOL and ZF ***
  2243 
  2244 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2245   with `addloop' of the simplifier to faciliate case splitting in premises.
  2246 
  2247 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2248 in HOL, they strip ALL and --> from proved theorems;
  2249 
  2250 
  2251 
  2252 New in Isabelle94-8 (May 1997)
  2253 ------------------------------
  2254 
  2255 *** General Changes ***
  2256 
  2257 * new utilities to build / run / maintain Isabelle etc. (in parts
  2258 still somewhat experimental); old Makefiles etc. still functional;
  2259 
  2260 * new 'Isabelle System Manual';
  2261 
  2262 * INSTALL text, together with ./configure and ./build scripts;
  2263 
  2264 * reimplemented type inference for greater efficiency, better error
  2265 messages and clean internal interface;
  2266 
  2267 * prlim command for dealing with lots of subgoals (an easier way of
  2268 setting goals_limit);
  2269 
  2270 
  2271 *** Syntax ***
  2272 
  2273 * supports alternative (named) syntax tables (parser and pretty
  2274 printer); internal interface is provided by add_modesyntax(_i);
  2275 
  2276 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2277 be used in conjunction with the Isabelle symbol font; uses the
  2278 "symbols" syntax table;
  2279 
  2280 * added token_translation interface (may translate name tokens in
  2281 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2282 the current print_mode); IMPORTANT: user print translation functions
  2283 are responsible for marking newly introduced bounds
  2284 (Syntax.mark_boundT);
  2285 
  2286 * token translations for modes "xterm" and "xterm_color" that display
  2287 names in bold, underline etc. or colors (which requires a color
  2288 version of xterm);
  2289 
  2290 * infixes may now be declared with names independent of their syntax;
  2291 
  2292 * added typed_print_translation (like print_translation, but may
  2293 access type of constant);
  2294 
  2295 
  2296 *** Classical Reasoner ***
  2297 
  2298 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2299 some limitations.  Blast_tac...
  2300   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2301   + ignores elimination rules that don't have the correct format
  2302         (the conclusion MUST be a formula variable)
  2303   + ignores types, which can make HOL proofs fail
  2304   + rules must not require higher-order unification, e.g. apply_type in ZF
  2305     [message "Function Var's argument not a bound variable" relates to this]
  2306   + its proof strategy is more general but can actually be slower
  2307 
  2308 * substitution with equality assumptions no longer permutes other
  2309 assumptions;
  2310 
  2311 * minor changes in semantics of addafter (now called addaltern); renamed
  2312 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2313 (and access functions for it);
  2314 
  2315 * improved combination of classical reasoner and simplifier:
  2316   + functions for handling clasimpsets
  2317   + improvement of addss: now the simplifier is called _after_ the
  2318     safe steps.
  2319   + safe variant of addss called addSss: uses safe simplifications
  2320     _during_ the safe steps. It is more complete as it allows multiple
  2321     instantiations of unknowns (e.g. with slow_tac).
  2322 
  2323 *** Simplifier ***
  2324 
  2325 * added interface for simplification procedures (functions that
  2326 produce *proven* rewrite rules on the fly, depending on current
  2327 redex);
  2328 
  2329 * ordering on terms as parameter (used for ordered rewriting);
  2330 
  2331 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2332 
  2333 * the solver is now split into a safe and an unsafe part.
  2334 This should be invisible for the normal user, except that the
  2335 functions setsolver and addsolver have been renamed to setSolver and
  2336 addSolver; added safe_asm_full_simp_tac;
  2337 
  2338 
  2339 *** HOL ***
  2340 
  2341 * a generic induction tactic `induct_tac' which works for all datatypes and
  2342 also for type `nat';
  2343 
  2344 * a generic case distinction tactic `exhaust_tac' which works for all
  2345 datatypes and also for type `nat';
  2346 
  2347 * each datatype comes with a function `size';
  2348 
  2349 * patterns in case expressions allow tuple patterns as arguments to
  2350 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2351 
  2352 * primrec now also works with type nat;
  2353 
  2354 * recdef: a new declaration form, allows general recursive functions to be
  2355 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2356 
  2357 * the constant for negation has been renamed from "not" to "Not" to
  2358 harmonize with FOL, ZF, LK, etc.;
  2359 
  2360 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2361 infinite lists;
  2362 
  2363 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2364 
  2365 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2366 problems in commutative rings, using axiomatic type classes for + and *;
  2367 
  2368 * more examples in HOL/MiniML and HOL/Auth;
  2369 
  2370 * more default rewrite rules for quantifiers, union/intersection;
  2371 
  2372 * a new constant `arbitrary == @x.False';
  2373 
  2374 * HOLCF/IOA replaces old HOL/IOA;
  2375 
  2376 * HOLCF changes: derived all rules and arities
  2377   + axiomatic type classes instead of classes
  2378   + typedef instead of faking type definitions
  2379   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2380   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2381   + eliminated the types void, one, tr
  2382   + use unit lift and bool lift (with translations) instead of one and tr
  2383   + eliminated blift from Lift3.thy (use Def instead of blift)
  2384   all eliminated rules are derived as theorems --> no visible changes ;
  2385 
  2386 
  2387 *** ZF ***
  2388 
  2389 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2390 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2391 as ZF_cs addSIs [equalityI];
  2392 
  2393 
  2394 
  2395 New in Isabelle94-7 (November 96)
  2396 ---------------------------------
  2397 
  2398 * allowing negative levels (as offsets) in prlev and choplev;
  2399 
  2400 * super-linear speedup for large simplifications;
  2401 
  2402 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2403 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2404 FAIL); can suppress it using the command Delsimps (ex_simps @
  2405 all_simps); De Morgan laws are also now included, by default;
  2406 
  2407 * improved printing of ==>  :  ~:
  2408 
  2409 * new object-logic "Sequents" adds linear logic, while replacing LK
  2410 and Modal (thanks to Sara Kalvala);
  2411 
  2412 * HOL/Auth: correctness proofs for authentication protocols;
  2413 
  2414 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2415 examples on HOL/Auth);
  2416 
  2417 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2418 the rewriter and classical reasoner simultaneously;
  2419 
  2420 * function uresult no longer returns theorems in "standard" format;
  2421 regain previous version by: val uresult = standard o uresult;
  2422 
  2423 
  2424 
  2425 New in Isabelle94-6
  2426 -------------------
  2427 
  2428 * oracles -- these establish an interface between Isabelle and trusted
  2429 external reasoners, which may deliver results as theorems;
  2430 
  2431 * proof objects (in particular record all uses of oracles);
  2432 
  2433 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2434 
  2435 * "constdefs" section in theory files;
  2436 
  2437 * "primrec" section (HOL) no longer requires names;
  2438 
  2439 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2440 
  2441 
  2442 
  2443 New in Isabelle94-5
  2444 -------------------
  2445 
  2446 * reduced space requirements;
  2447 
  2448 * automatic HTML generation from theories;
  2449 
  2450 * theory files no longer require "..." (quotes) around most types;
  2451 
  2452 * new examples, including two proofs of the Church-Rosser theorem;
  2453 
  2454 * non-curried (1994) version of HOL is no longer distributed;
  2455 
  2456 
  2457 
  2458 New in Isabelle94-4
  2459 -------------------
  2460 
  2461 * greatly reduced space requirements;
  2462 
  2463 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2464 
  2465 * searchable theorem database (see the section "Retrieving theorems" on
  2466 page 8 of the Reference Manual);
  2467 
  2468 * new examples, including Grabczewski's monumental case study of the
  2469 Axiom of Choice;
  2470 
  2471 * The previous version of HOL renamed to Old_HOL;
  2472 
  2473 * The new version of HOL (previously called CHOL) uses a curried syntax
  2474 for functions.  Application looks like f a b instead of f(a,b);
  2475 
  2476 * Mutually recursive inductive definitions finally work in HOL;
  2477 
  2478 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2479 translates to the operator "split";
  2480 
  2481 
  2482 
  2483 New in Isabelle94-3
  2484 -------------------
  2485 
  2486 * new infix operator, addss, allowing the classical reasoner to
  2487 perform simplification at each step of its search.  Example:
  2488         fast_tac (cs addss ss)
  2489 
  2490 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2491 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2492 look like (a,b) instead of <a,b>;
  2493 
  2494 * PLEASE NOTE: CHOL will eventually replace HOL!
  2495 
  2496 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2497 It translates to the operator "split".  A new theory of integers is available;
  2498 
  2499 * In ZF, integer numerals now denote two's-complement binary integers.
  2500 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2501 
  2502 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2503 of the Axiom of Choice;
  2504 
  2505 
  2506 
  2507 New in Isabelle94-2
  2508 -------------------
  2509 
  2510 * Significantly faster resolution;
  2511 
  2512 * the different sections in a .thy file can now be mixed and repeated
  2513 freely;
  2514 
  2515 * Database of theorems for FOL, HOL and ZF.  New
  2516 commands including qed, qed_goal and bind_thm store theorems in the database.
  2517 
  2518 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2519 a given theory (thms_of), or find out what theory a theorem was proved in
  2520 (theory_of_thm);
  2521 
  2522 * Bugs fixed in the inductive definition and datatype packages;
  2523 
  2524 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2525 and HOL_dup_cs obsolete;
  2526 
  2527 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2528 have been removed;
  2529 
  2530 * Simpler definition of function space in ZF;
  2531 
  2532 * new results about cardinal and ordinal arithmetic in ZF;
  2533 
  2534 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2535 types;
  2536 
  2537 
  2538 $Id$