NEWS
author schirmer
Wed Mar 03 22:58:23 2004 +0100 (2004-03-03)
changeset 14427 cea7d2f76112
parent 14418 b62323c85134
child 14464 72ad5f2a3803
permissions -rw-r--r--
added record_ex_sel_eq_simproc
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** General ***
     8 
     9 * Provers/order.ML:  new efficient reasoner for partial and linear orders.
    10   Replaces linorder.ML.
    11 
    12 * Pure: Greek letters (except small lambda, \<lambda>), as well as gothic
    13   (\<aa>...\<zz>\<AA>...\<ZZ>), caligraphic (\<A>...\<Z>), and euler
    14   (\<a>...\<z>), are now considered normal letters, and can therefore
    15   be used anywhere where an ASCII letter (a...zA...Z) has until
    16   now. COMPATIBILITY: This obviously changes the parsing of some
    17   terms, especially where a symbol has been used as a binder, say
    18   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed
    19   as an identifier.  Fix it by inserting a space around former
    20   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in
    21   existing theory and ML files.
    22 
    23 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.
    24 
    25 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now 
    26   allowed in identifiers. Similar to greek letters \<^isub> is now considered 
    27   a normal (but invisible) letter. For multiple letter subscripts repeat 
    28   \<^isub> like this: x\<^isub>1\<^isub>2. 
    29 
    30 * Pure: There are now sub-/superscripts that can span more than one
    31   character. Text between \<^bsub> and \<^esub> is set in subscript in
    32   PG and LaTeX, text between \<^bsup> and \<^esup> in superscript. The
    33   new control characters are not identifier parts.
    34 
    35 * Pure: Control-symbols of the form \<^raw...> will literally print the
    36   content of ... to the latex file instead of \isacntrl... . The ... 
    37   accepts all printable characters excluding the end bracket >.
    38 
    39 * Pure: Symbols may only start with one backslash: \<...>. \\<...> is no 
    40   longer accepted by the scanner.
    41 
    42 * Pure: Using new Isar command "finalconsts" (or the ML functions
    43   Theory.add_finals or Theory.add_finals_i) it is now possible to
    44   declare constants "final", which prevents their being given a definition
    45   later.  It is useful for constants whose behaviour is fixed axiomatically
    46   rather than definitionally, such as the meta-logic connectives.
    47 
    48 *** Isar ***
    49 
    50 * Tactic emulation methods ?rule_tac, cut_tac, subgoal_tac and thin_tac:
    51   - Now understand static (Isar) contexts.  As a consequence, users of Isar
    52     locales are no longer forced to write Isar proof scripts.
    53     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
    54     emulations.
    55   - INCOMPATIBILITY: names of variables to be instantiated may no
    56     longer be enclosed in quotes.  Instead, precede variable name with `?'.
    57     This is consistent with the instantiation attribute "where".
    58 
    59 * Attributes "where" and "of":
    60   - Now take type variables of instantiated theorem into account when reading
    61     the instantiation string.  This fixes a bug that caused instantiated
    62     theorems to have too special types in some circumstances.
    63   - "where" permits explicit instantiations of type variables.
    64 
    65 * Calculation commands "moreover" and "also":
    66   Do not reset facts ("this") any more.
    67 
    68 * Locales:
    69   - Goal statements involving the context element "includes" no longer
    70     generate theorems with internal delta predicates (those ending on
    71     "_axioms") in the premise.
    72     Resolve particular premise with <locale>.intro to obtain old form.
    73   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
    74     specification and "includes" elements in goal statement.
    75   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
    76     [intro?] and [elim?] (respectively) by default.
    77 
    78 * HOL: Tactic emulation methods induct_tac and case_tac understand static
    79   (Isar) contexts.
    80 
    81 *** HOL ***
    82 
    83 * Simplifier:
    84   - Much improved handling of linear and partial orders.
    85     Reasoners for linear and partial orders are set up for type classes
    86     "linorder" and "order" respectively, and are added to the default simpset
    87     as solvers.  This means that the simplifier can build transitivity chains
    88     to solve goals from the assumptions.
    89   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications
    90     of blast or auto after simplification become unnecessary because the goal
    91     is solved by simplification already.
    92 
    93 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws, 
    94     all proved in axiomatic type classes for semirings, rings and fields.
    95 
    96 * Numerics:
    97   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are
    98     now formalized using the Ring_and_Field theory mentioned above. 
    99   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently
   100     than before, because now they are set up once in a generic manner.
   101   - INCOMPATIBILITY: many type-specific instances of laws proved in 
   102     Ring_and_Field are no longer available.
   103 
   104 * Type "rat" of the rational numbers is now available in HOL-Complex.
   105 
   106 * Records:
   107   - Record types are now by default printed with their type abbreviation
   108     instead of the list of all field types. This can be configured via
   109     the reference "print_record_type_abbr".
   110   - Simproc "record_upd_simproc" for simplification of multiple updates added 
   111     (not enabled by default).
   112   - Simproc "record_ex_sel_eq_simproc" to simplify EX x. sel r = x resp.
   113     EX x. x = sel r to True (not enabled by default).
   114   - Tactic "record_split_simp_tac" to split and simplify records added.
   115  
   116 * 'specification' command added, allowing for definition by
   117   specification.  There is also an 'ax_specification' command that
   118   introduces the new constants axiomatically.
   119 
   120 * arith(_tac) is now able to generate counterexamples for reals as well.
   121 
   122 * HOL-Algebra: new locale "ring" for non-commutative rings.
   123 
   124 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
   125  defintions, thanks to Sava Krsti\'{c} and John Matthews.
   126 
   127 * Unions and Intersections:
   128   The x-symbol output syntax of UN and INT has been changed
   129   from "\<Union>x \<in> A. B" to "\<Union\<^bsub>x \<in> A\<^esub> B"
   130   i.e. the index formulae has become a subscript, like in normal math.
   131   Similarly for "\<Union>x. B", and for \<Inter> instead of \<Union>.
   132   The subscript version is also accepted as input syntax.
   133 
   134 * Unions and Intersections over Intervals:
   135   There is new short syntax "UN i<=n. A" for "UN i:{0..n}. A". There is 
   136   also an x-symbol version with subscripts "\<Union>\<^bsub>i <= n\<^esub>. A" 
   137   like in normal math, and corresponding versions for < and for intersection.
   138 
   139 * ML: the legacy theory structures Int and List have been removed. They had
   140   conflicted with ML Basis Library structures having the same names.
   141 
   142 New in Isabelle2003 (May 2003)
   143 --------------------------------
   144 
   145 *** General ***
   146 
   147 * Provers/simplifier:
   148 
   149   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   150     Assumptions are now subject to complete mutual simplification,
   151     not just from left to right. The simplifier now preserves
   152     the order of assumptions.
   153 
   154     Potential INCOMPATIBILITY:
   155 
   156     -- simp sometimes diverges where the old version did
   157        not, e.g. invoking simp on the goal
   158 
   159         [| P (f x); y = x; f x = f y |] ==> Q
   160 
   161        now gives rise to the infinite reduction sequence
   162 
   163         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   164 
   165        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   166        kind of problem.
   167 
   168     -- Tactics combining classical reasoner and simplification (such as auto)
   169        are also affected by this change, because many of them rely on
   170        simp. They may sometimes diverge as well or yield a different numbers
   171        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   172        in case of problems. Sometimes subsequent calls to the classical
   173        reasoner will fail because a preceeding call to the simplifier too
   174        eagerly simplified the goal, e.g. deleted redundant premises.
   175 
   176   - The simplifier trace now shows the names of the applied rewrite rules
   177 
   178   - You can limit the number of recursive invocations of the simplifier
   179     during conditional rewriting (where the simplifie tries to solve the
   180     conditions before applying the rewrite rule):
   181     ML "simp_depth_limit := n"
   182     where n is an integer. Thus you can force termination where previously
   183     the simplifier would diverge.
   184 
   185   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   186 
   187   - No longer aborts on failed congruence proof.  Instead, the
   188     congruence is ignored.
   189 
   190 * Pure: New generic framework for extracting programs from constructive
   191   proofs. See HOL/Extraction.thy for an example instantiation, as well
   192   as HOL/Extraction for some case studies.
   193 
   194 * Pure: The main goal of the proof state is no longer shown by default, only
   195 the subgoals. This behaviour is controlled by a new flag.
   196    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   197 (ML: Proof.show_main_goal).
   198 
   199 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   200 rules whose conclusion matches subgoal 1:
   201       PG menu: Isabelle/Isar -> Show me -> matching rules
   202 The rules are ordered by how closely they match the subgoal.
   203 In particular, rules that solve a subgoal outright are displayed first
   204 (or rather last, the way they are printed).
   205 (ML: ProofGeneral.print_intros())
   206 
   207 * Pure: New flag trace_unify_fail causes unification to print
   208 diagnostic information (PG: in trace buffer) when it fails. This is
   209 useful for figuring out why single step proofs like rule, erule or
   210 assumption failed.
   211 
   212 * Pure: Locale specifications now produce predicate definitions
   213 according to the body of text (covering assumptions modulo local
   214 definitions); predicate "loc_axioms" covers newly introduced text,
   215 while "loc" is cumulative wrt. all included locale expressions; the
   216 latter view is presented only on export into the global theory
   217 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   218 on the old view without predicates;
   219 
   220 * Pure: predefined locales "var" and "struct" are useful for sharing
   221 parameters (as in CASL, for example); just specify something like
   222 ``var x + var y + struct M'' as import;
   223 
   224 * Pure: improved thms_containing: proper indexing of facts instead of
   225 raw theorems; check validity of results wrt. current name space;
   226 include local facts of proof configuration (also covers active
   227 locales), cover fixed variables in index; may use "_" in term
   228 specification; an optional limit for the number of printed facts may
   229 be given (the default is 40);
   230 
   231 * Pure: disallow duplicate fact bindings within new-style theory files
   232 (batch-mode only);
   233 
   234 * Provers: improved induct method: assumptions introduced by case
   235 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   236 the goal statement); "foo" still refers to all facts collectively;
   237 
   238 * Provers: the function blast.overloaded has been removed: all constants
   239 are regarded as potentially overloaded, which improves robustness in exchange
   240 for slight decrease in efficiency;
   241 
   242 * Provers/linorder: New generic prover for transitivity reasoning over
   243 linear orders.  Note: this prover is not efficient!
   244 
   245 * Isar: preview of problems to finish 'show' now produce an error
   246 rather than just a warning (in interactive mode);
   247 
   248 
   249 *** HOL ***
   250 
   251 * arith(_tac)
   252 
   253  - Produces a counter example if it cannot prove a goal.
   254    Note that the counter example may be spurious if the goal is not a formula
   255    of quantifier-free linear arithmetic.
   256    In ProofGeneral the counter example appears in the trace buffer.
   257 
   258  - Knows about div k and mod k where k is a numeral of type nat or int.
   259 
   260  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   261    linear arithmetic fails. This takes account of quantifiers and divisibility.
   262    Presburger arithmetic can also be called explicitly via presburger(_tac). 
   263 
   264 * simp's arithmetic capabilities have been enhanced a bit: it now
   265 takes ~= in premises into account (by performing a case split);
   266 
   267 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   268 are distributed over a sum of terms;
   269 
   270 * New tactic "trans_tac" and method "trans" instantiate
   271 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   272 "<=", "<" and "="). 
   273 
   274 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main 
   275 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   276 
   277 * 'typedef' command has new option "open" to suppress the set
   278 definition;
   279 
   280 * functions Min and Max on finite sets have been introduced (theory
   281 Finite_Set);
   282 
   283 * attribute [symmetric] now works for relations as well; it turns
   284 (x,y) : R^-1 into (y,x) : R, and vice versa;
   285 
   286 * induct over a !!-quantified statement (say !!x1..xn):
   287   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   288 
   289 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   290 %x. None. Warning: empty_def now refers to the previously hidden definition
   291 of the empty set.
   292 
   293 * Algebra: formalization of classical algebra.  Intended as base for
   294 any algebraic development in Isabelle.  Currently covers group theory
   295 (up to Sylow's theorem) and ring theory (Universal Property of
   296 Univariate Polynomials).  Contributions welcome;
   297 
   298 * GroupTheory: deleted, since its material has been moved to Algebra;
   299 
   300 * Complex: new directory of the complex numbers with numeric constants, 
   301 nonstandard complex numbers, and some complex analysis, standard and 
   302 nonstandard (Jacques Fleuriot);
   303 
   304 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   305 
   306 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques 
   307 Fleuriot);
   308 
   309 * Real/HahnBanach: updated and adapted to locales;
   310 
   311 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   312 Gray and Kramer);
   313 
   314 * UNITY: added the Meier-Sanders theory of progress sets;
   315 
   316 * MicroJava: bytecode verifier and lightweight bytecode verifier
   317 as abstract algorithms, instantiated to the JVM;
   318 
   319 * Bali: Java source language formalization. Type system, operational
   320 semantics, axiomatic semantics. Supported language features:
   321 classes, interfaces, objects,virtual methods, static methods,
   322 static/instance fields, arrays, access modifiers, definite
   323 assignment, exceptions.
   324 
   325 
   326 *** ZF ***
   327 
   328 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   329 universe, etc.);
   330 
   331 * Main ZF: virtually all theories converted to new-style format;
   332 
   333 
   334 *** ML ***
   335 
   336 * Pure: Tactic.prove provides sane interface for internal proofs;
   337 omits the infamous "standard" operation, so this is more appropriate
   338 than prove_goalw_cterm in many situations (e.g. in simprocs);
   339 
   340 * Pure: improved error reporting of simprocs;
   341 
   342 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   343 up simprocs;
   344 
   345 
   346 *** Document preparation ***
   347 
   348 * uses \par instead of \\ for line breaks in theory text. This may
   349 shift some page breaks in large documents. To get the old behaviour
   350 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   351 
   352 * minimized dependencies of isabelle.sty and isabellesym.sty on 
   353 other packages
   354 
   355 * \<euro> now needs package babel/greek instead of marvosym (which
   356 broke \Rightarrow)
   357 
   358 * normal size for \<zero>...\<nine> (uses \mathbf instead of 
   359 textcomp package)
   360 
   361 
   362 New in Isabelle2002 (March 2002)
   363 --------------------------------
   364 
   365 *** Document preparation ***
   366 
   367 * greatly simplified document preparation setup, including more
   368 graceful interpretation of isatool usedir -i/-d/-D options, and more
   369 instructive isatool mkdir; users should basically be able to get
   370 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   371 users may run a separate document processing stage manually like this:
   372 "isatool usedir -D output HOL Test && isatool document Test/output";
   373 
   374 * theory dependency graph may now be incorporated into documents;
   375 isatool usedir -g true will produce session_graph.eps/.pdf for use
   376 with \includegraphics of LaTeX;
   377 
   378 * proper spacing of consecutive markup elements, especially text
   379 blocks after section headings;
   380 
   381 * support bold style (for single symbols only), input syntax is like
   382 this: "\<^bold>\<alpha>" or "\<^bold>A";
   383 
   384 * \<bullet> is now output as bold \cdot by default, which looks much
   385 better in printed text;
   386 
   387 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   388 note that these symbols are currently unavailable in Proof General /
   389 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   390 
   391 * isatool latex no longer depends on changed TEXINPUTS, instead
   392 isatool document copies the Isabelle style files to the target
   393 location;
   394 
   395 
   396 *** Isar ***
   397 
   398 * Pure/Provers: improved proof by cases and induction;
   399   - 'case' command admits impromptu naming of parameters (such as
   400     "case (Suc n)");
   401   - 'induct' method divinates rule instantiation from the inductive
   402     claim; no longer requires excessive ?P bindings for proper
   403     instantiation of cases;
   404   - 'induct' method properly enumerates all possibilities of set/type
   405     rules; as a consequence facts may be also passed through *type*
   406     rules without further ado;
   407   - 'induct' method now derives symbolic cases from the *rulified*
   408     rule (before it used to rulify cases stemming from the internal
   409     atomized version); this means that the context of a non-atomic
   410     statement becomes is included in the hypothesis, avoiding the
   411     slightly cumbersome show "PROP ?case" form;
   412   - 'induct' may now use elim-style induction rules without chaining
   413     facts, using ``missing'' premises from the goal state; this allows
   414     rules stemming from inductive sets to be applied in unstructured
   415     scripts, while still benefitting from proper handling of non-atomic
   416     statements; NB: major inductive premises need to be put first, all
   417     the rest of the goal is passed through the induction;
   418   - 'induct' proper support for mutual induction involving non-atomic
   419     rule statements (uses the new concept of simultaneous goals, see
   420     below);
   421   - append all possible rule selections, but only use the first
   422     success (no backtracking);
   423   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   424   - undeclared rule case names default to numbers 1, 2, 3, ...;
   425   - added 'print_induct_rules' (covered by help item in recent Proof
   426     General versions);
   427   - moved induct/cases attributes to Pure, methods to Provers;
   428   - generic method setup instantiated for FOL and HOL;
   429 
   430 * Pure: support multiple simultaneous goal statements, for example
   431 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   432 meta-level mechanism, this acts as if several individual goals had
   433 been stated separately; in particular common proof methods need to be
   434 repeated in order to cover all claims; note that a single elimination
   435 step is *not* sufficient to establish the two conjunctions, so this
   436 fails:
   437 
   438   assume "A & B" then have A and B ..   (*".." fails*)
   439 
   440 better use "obtain" in situations as above; alternative refer to
   441 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   442 
   443 * Pure: proper integration with ``locales''; unlike the original
   444 version by Florian Kammüller, Isar locales package high-level proof
   445 contexts rather than raw logical ones (e.g. we admit to include
   446 attributes everywhere); operations on locales include merge and
   447 rename; support for implicit arguments (``structures''); simultaneous
   448 type-inference over imports and text; see also HOL/ex/Locales.thy for
   449 some examples;
   450 
   451 * Pure: the following commands have been ``localized'', supporting a
   452 target locale specification "(in name)": 'lemma', 'theorem',
   453 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   454 stored both within the locale and at the theory level (exported and
   455 qualified by the locale name);
   456 
   457 * Pure: theory goals may now be specified in ``long'' form, with
   458 ad-hoc contexts consisting of arbitrary locale elements. for example
   459 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   460 definitions may be given, too); the result is a meta-level rule with
   461 the context elements being discharged in the obvious way;
   462 
   463 * Pure: new proof command 'using' allows to augment currently used
   464 facts after a goal statement ('using' is syntactically analogous to
   465 'apply', but acts on the goal's facts only); this allows chained facts
   466 to be separated into parts given before and after a claim, as in
   467 ``from a and b have C using d and e <proof>'';
   468 
   469 * Pure: renamed "antecedent" case to "rule_context";
   470 
   471 * Pure: new 'judgment' command records explicit information about the
   472 object-logic embedding (used by several tools internally); no longer
   473 use hard-wired "Trueprop";
   474 
   475 * Pure: added 'corollary' command;
   476 
   477 * Pure: fixed 'token_translation' command;
   478 
   479 * Pure: removed obsolete 'exported' attribute;
   480 
   481 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   482 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   483 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   484 
   485 * Pure: method 'atomize' presents local goal premises as object-level
   486 statements (atomic meta-level propositions); setup controlled via
   487 rewrite rules declarations of 'atomize' attribute; example
   488 application: 'induct' method with proper rule statements in improper
   489 proof *scripts*;
   490 
   491 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   492 now consider the syntactic context of assumptions, giving a better
   493 chance to get type-inference of the arguments right (this is
   494 especially important for locales);
   495 
   496 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   497 mode;
   498 
   499 * Pure/obtain: the formal conclusion "thesis", being marked as
   500 ``internal'', may no longer be reference directly in the text;
   501 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   502 situations;
   503 
   504 * Pure: generic 'sym' attribute which declares a rule both as pure
   505 'elim?' and for the 'symmetric' operation;
   506 
   507 * Pure: marginal comments ``--'' may now occur just anywhere in the
   508 text; the fixed correlation with particular command syntax has been
   509 discontinued;
   510 
   511 * Pure: new method 'rules' is particularly well-suited for proof
   512 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   513 but often produces more compact proof terms with less detours;
   514 
   515 * Pure/Provers/classical: simplified integration with pure rule
   516 attributes and methods; the classical "intro?/elim?/dest?"
   517 declarations coincide with the pure ones; the "rule" method no longer
   518 includes classically swapped intros; "intro" and "elim" methods no
   519 longer pick rules from the context; also got rid of ML declarations
   520 AddXIs/AddXEs/AddXDs; all of this has some potential for
   521 INCOMPATIBILITY;
   522 
   523 * Provers/classical: attribute 'swapped' produces classical inversions
   524 of introduction rules;
   525 
   526 * Provers/simplifier: 'simplified' attribute may refer to explicit
   527 rules instead of full simplifier context; 'iff' attribute handles
   528 conditional rules;
   529 
   530 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   531 
   532 * HOL: 'recdef' now fails on unfinished automated proofs, use
   533 "(permissive)" option to recover old behavior;
   534 
   535 * HOL: 'inductive' no longer features separate (collective) attributes
   536 for 'intros' (was found too confusing);
   537 
   538 * HOL: properly declared induction rules less_induct and
   539 wf_induct_rule;
   540 
   541 
   542 *** HOL ***
   543 
   544 * HOL: moved over to sane numeral syntax; the new policy is as
   545 follows:
   546 
   547   - 0 and 1 are polymorphic constants, which are defined on any
   548   numeric type (nat, int, real etc.);
   549 
   550   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   551   binary representation internally;
   552 
   553   - type nat has special constructor Suc, and generally prefers Suc 0
   554   over 1::nat and Suc (Suc 0) over 2::nat;
   555 
   556 This change may cause significant problems of INCOMPATIBILITY; here
   557 are some hints on converting existing sources:
   558 
   559   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   560   entities, so expressions involving "-" (unary or binary minus) need
   561   to be spaced properly;
   562 
   563   - existing occurrences of "1" may need to be constraint "1::nat" or
   564   even replaced by Suc 0; similar for old "2";
   565 
   566   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   567 
   568   - remove all special provisions on numerals in proofs;
   569 
   570 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   571 representation (depends on bin_arith_simps in the default context);
   572 
   573 * HOL: symbolic syntax for x^2 (numeral 2);
   574 
   575 * HOL: the class of all HOL types is now called "type" rather than
   576 "term"; INCOMPATIBILITY, need to adapt references to this type class
   577 in axclass/classes, instance/arities, and (usually rare) occurrences
   578 in typings (of consts etc.); internally the class is called
   579 "HOL.type", ML programs should refer to HOLogic.typeS;
   580 
   581 * HOL/record package improvements:
   582   - new derived operations "fields" to build a partial record section,
   583     "extend" to promote a fixed record to a record scheme, and
   584     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   585     declared as simp by default;
   586   - shared operations ("more", "fields", etc.) now need to be always
   587     qualified) --- potential INCOMPATIBILITY;
   588   - removed "make_scheme" operations (use "make" with "extend") --
   589     INCOMPATIBILITY;
   590   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   591   - provides cases/induct rules for use with corresponding Isar
   592     methods (for concrete records, record schemes, concrete more
   593     parts, and schematic more parts -- in that order);
   594   - internal definitions directly based on a light-weight abstract
   595     theory of product types over typedef rather than datatype;
   596 
   597 * HOL: generic code generator for generating executable ML code from
   598 specifications; specific support for HOL constructs such as inductive
   599 datatypes and sets, as well as recursive functions; can be invoked
   600 via 'generate_code' theory section;
   601 
   602 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   603 
   604 * HOL: consolidated and renamed several theories.  In particular:
   605 	Ord.thy has been absorbed into HOL.thy
   606 	String.thy has been absorbed into List.thy
   607  
   608 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   609 (beware of argument permutation!);
   610 
   611 * HOL: linorder_less_split superseded by linorder_cases;
   612 
   613 * HOL/List: "nodups" renamed to "distinct";
   614 
   615 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   616 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   617   - Ex_def has changed, now need to use some_eq_ex
   618 
   619 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   620 in this (rare) case use:
   621 
   622   delSWrapper "split_all_tac"
   623   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   624 
   625 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   626 MAY FAIL;
   627 
   628 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   629 Isabelle's type classes, ^ on functions and relations has too general
   630 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   631 necessary to attach explicit type constraints;
   632 
   633 * HOL/Relation: the prefix name of the infix "O" has been changed from
   634 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   635 renamed accordingly (eg "compI" -> "rel_compI").
   636 
   637 * HOL: syntax translations now work properly with numerals and records
   638 expressions;
   639 
   640 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   641 of "lam" -- INCOMPATIBILITY;
   642 
   643 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   644 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   645 renamed "Product_Type.unit";
   646 
   647 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   648 
   649 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   650 the "cases" method);
   651 
   652 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   653 Florian Kammüller);
   654 
   655 * HOL/IMP: updated and converted to new-style theory format; several
   656 parts turned into readable document, with proper Isar proof texts and
   657 some explanations (by Gerwin Klein);
   658 
   659 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   660 
   661 * HOL-Hyperreal is now a logic image;
   662 
   663 
   664 *** HOLCF ***
   665 
   666 * Isar: consts/constdefs supports mixfix syntax for continuous
   667 operations;
   668 
   669 * Isar: domain package adapted to new-style theory format, e.g. see
   670 HOLCF/ex/Dnat.thy;
   671 
   672 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   673 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   674 lift.induct_tac, always use UU instead of Undef;
   675 
   676 * HOLCF/IMP: updated and converted to new-style theory;
   677 
   678 
   679 *** ZF ***
   680 
   681 * Isar: proper integration of logic-specific tools and packages,
   682 including theory commands '(co)inductive', '(co)datatype',
   683 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   684 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   685 
   686 * theory Main no longer includes AC; for the Axiom of Choice, base
   687 your theory on Main_ZFC;
   688 
   689 * the integer library now covers quotients and remainders, with many
   690 laws relating division to addition, multiplication, etc.;
   691 
   692 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   693 typeless version of the formalism;
   694 
   695 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   696 format;
   697 
   698 * ZF/Induct: new directory for examples of inductive definitions,
   699 including theory Multiset for multiset orderings; converted to
   700 new-style theory format;
   701 
   702 * ZF: many new theorems about lists, ordinals, etc.;
   703 
   704 
   705 *** General ***
   706 
   707 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   708 variable proof controls level of detail: 0 = no proofs (only oracle
   709 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   710 also ref manual for further ML interfaces;
   711 
   712 * Pure/axclass: removed obsolete ML interface
   713 goal_subclass/goal_arity;
   714 
   715 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   716 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   717 separate tokens, so expressions involving minus need to be spaced
   718 properly;
   719 
   720 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   721 rather than "infixl" or "infixr";
   722 
   723 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   724 sort constraint specifications in type inference; e.g. "x::_::foo"
   725 ensures that the type of "x" is of sort "foo" (but not necessarily a
   726 type variable);
   727 
   728 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   729 control output of nested => (types); the default behavior is
   730 "type_brackets";
   731 
   732 * Pure/syntax: builtin parse translation for "_constify" turns valued
   733 tokens into AST constants;
   734 
   735 * Pure/syntax: prefer later declarations of translations and print
   736 translation functions; potential INCOMPATIBILITY: need to reverse
   737 multiple declarations for same syntax element constant;
   738 
   739 * Pure/show_hyps reset by default (in accordance to existing Isar
   740 practice);
   741 
   742 * Provers/classical: renamed addaltern to addafter, addSaltern to
   743 addSafter;
   744 
   745 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   746 as well;
   747 
   748 * system: tested support for MacOS X; should be able to get Isabelle +
   749 Proof General to work in a plain Terminal after installing Poly/ML
   750 (e.g. from the Isabelle distribution area) and GNU bash alone
   751 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   752 support requires further installations, e.g. from
   753 http://fink.sourceforge.net/);
   754 
   755 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   756 
   757 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   758 of 40 MB), cf. ML_OPTIONS;
   759 
   760 * system: Proof General keywords specification is now part of the
   761 Isabelle distribution (see etc/isar-keywords.el);
   762 
   763 * system: support for persistent Proof General sessions (refrain from
   764 outdating all loaded theories on startup); user may create writable
   765 logic images like this: ``isabelle -q HOL Test'';
   766 
   767 * system: smart selection of Isabelle process versus Isabelle
   768 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   769 run both "isabelle" and "Isabelle" even if file names are badly
   770 damaged (executable inspects the case of the first letter of its own
   771 name); added separate "isabelle-process" and "isabelle-interface";
   772 
   773 * system: refrain from any attempt at filtering input streams; no
   774 longer support ``8bit'' encoding of old isabelle font, instead proper
   775 iso-latin characters may now be used; the related isatools
   776 "symbolinput" and "nonascii" have disappeared as well;
   777 
   778 * system: removed old "xterm" interface (the print modes "xterm" and
   779 "xterm_color" are still available for direct use in a suitable
   780 terminal);
   781 
   782 
   783 
   784 New in Isabelle99-2 (February 2001)
   785 -----------------------------------
   786 
   787 *** Overview of INCOMPATIBILITIES ***
   788 
   789 * HOL: please note that theories in the Library and elsewhere often use the
   790 new-style (Isar) format; to refer to their theorems in an ML script you must
   791 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   792 
   793 * HOL: inductive package no longer splits induction rule aggressively,
   794 but only as far as specified by the introductions given; the old
   795 format may be recovered via ML function complete_split_rule or attribute
   796 'split_rule (complete)';
   797 
   798 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   799 gfp_Tarski to gfp_unfold;
   800 
   801 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   802 
   803 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   804 relation); infix "^^" has been renamed "``"; infix "``" has been
   805 renamed "`"; "univalent" has been renamed "single_valued";
   806 
   807 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   808 operation;
   809 
   810 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   811 
   812 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   813 
   814 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   815 consequence, it is no longer monotonic wrt. the local goal context
   816 (which is now passed through the inductive cases);
   817 
   818 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   819 \<gg> to \<ggreater>;
   820 
   821 
   822 *** Document preparation ***
   823 
   824 * \isabellestyle{NAME} selects version of Isabelle output (currently
   825 available: are "it" for near math-mode best-style output, "sl" for
   826 slanted text style, and "tt" for plain type-writer; if no
   827 \isabellestyle command is given, output is according to slanted
   828 type-writer);
   829 
   830 * support sub/super scripts (for single symbols only), input syntax is
   831 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   832 
   833 * some more standard symbols; see Appendix A of the system manual for
   834 the complete list of symbols defined in isabellesym.sty;
   835 
   836 * improved isabelle style files; more abstract symbol implementation
   837 (should now use \isamath{...} and \isatext{...} in custom symbol
   838 definitions);
   839 
   840 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   841 state; Note that presentation of goal states does not conform to
   842 actual human-readable proof documents.  Please do not include goal
   843 states into document output unless you really know what you are doing!
   844 
   845 * proper indentation of antiquoted output with proportional LaTeX
   846 fonts;
   847 
   848 * no_document ML operator temporarily disables LaTeX document
   849 generation;
   850 
   851 * isatool unsymbolize tunes sources for plain ASCII communication;
   852 
   853 
   854 *** Isar ***
   855 
   856 * Pure: Isar now suffers initial goal statements to contain unbound
   857 schematic variables (this does not conform to actual readable proof
   858 documents, due to unpredictable outcome and non-compositional proof
   859 checking); users who know what they are doing may use schematic goals
   860 for Prolog-style synthesis of proven results;
   861 
   862 * Pure: assumption method (an implicit finishing) now handles actual
   863 rules as well;
   864 
   865 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   866 initial goal, declare "that" only as Pure intro (only for single
   867 steps); the "that" rule assumption may now be involved in implicit
   868 finishing, thus ".." becomes a feasible for trivial obtains;
   869 
   870 * Pure: default proof step now includes 'intro_classes'; thus trivial
   871 instance proofs may be performed by "..";
   872 
   873 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   874 statements as well;
   875 
   876 * Pure: more robust selection of calculational rules;
   877 
   878 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   879 rule (as well as the assumption rule);
   880 
   881 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   882 lemmas, using the graph browser tool;
   883 
   884 * Pure: predict failure of "show" in interactive mode;
   885 
   886 * Pure: 'thms_containing' now takes actual terms as arguments;
   887 
   888 * HOL: improved method 'induct' --- now handles non-atomic goals
   889 (potential INCOMPATIBILITY); tuned error handling;
   890 
   891 * HOL: cases and induct rules now provide explicit hints about the
   892 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   893 any remaining facts are inserted into the goal verbatim;
   894 
   895 * HOL: local contexts (aka cases) may now contain term bindings as
   896 well; the 'cases' and 'induct' methods new provide a ?case binding for
   897 the result to be shown in each case;
   898 
   899 * HOL: added 'recdef_tc' command;
   900 
   901 * isatool convert assists in eliminating legacy ML scripts;
   902 
   903 
   904 *** HOL ***
   905 
   906 * HOL/Library: a collection of generic theories to be used together
   907 with main HOL; the theory loader path already includes this directory
   908 by default; the following existing theories have been moved here:
   909 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   910 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   911 
   912 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   913 modelling and verification task performed in Isabelle/HOL +
   914 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   915 
   916 * HOL/Algebra: special summation operator SUM no longer exists, it has
   917 been replaced by setsum; infix 'assoc' now has priority 50 (like
   918 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   919 'domain', this makes the theory consistent with mathematical
   920 literature;
   921 
   922 * HOL basics: added overloaded operations "inverse" and "divide"
   923 (infix "/"), syntax for generic "abs" operation, generic summation
   924 operator \<Sum>;
   925 
   926 * HOL/typedef: simplified package, provide more useful rules (see also
   927 HOL/subset.thy);
   928 
   929 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   930 now expressed as a proper nested rule (old-style tactic scripts may
   931 require atomize_strip_tac to cope with non-atomic premises);
   932 
   933 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   934 to "split_conv" (old name still available for compatibility);
   935 
   936 * HOL: improved concrete syntax for strings (e.g. allows translation
   937 rules with string literals);
   938 
   939 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   940  and Fleuriot's mechanization of analysis, including the transcendental
   941  functions for the reals;
   942 
   943 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   944 
   945 
   946 *** CTT ***
   947 
   948 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   949 "lam" is displayed as TWO lambda-symbols
   950 
   951 * CTT: theory Main now available, containing everything (that is, Bool
   952 and Arith);
   953 
   954 
   955 *** General ***
   956 
   957 * Pure: the Simplifier has been implemented properly as a derived rule
   958 outside of the actual kernel (at last!); the overall performance
   959 penalty in practical applications is about 50%, while reliability of
   960 the Isabelle inference kernel has been greatly improved;
   961 
   962 * print modes "brackets" and "no_brackets" control output of nested =>
   963 (types) and ==> (props); the default behaviour is "brackets";
   964 
   965 * Provers: fast_tac (and friends) now handle actual object-logic rules
   966 as assumptions as well;
   967 
   968 * system: support Poly/ML 4.0;
   969 
   970 * system: isatool install handles KDE version 1 or 2;
   971 
   972 
   973 
   974 New in Isabelle99-1 (October 2000)
   975 ----------------------------------
   976 
   977 *** Overview of INCOMPATIBILITIES ***
   978 
   979 * HOL: simplification of natural numbers is much changed; to partly
   980 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   981 issue the following ML commands:
   982 
   983   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   984   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   985 
   986 * HOL: simplification no longer dives into case-expressions; this is
   987 controlled by "t.weak_case_cong" for each datatype t;
   988 
   989 * HOL: nat_less_induct renamed to less_induct;
   990 
   991 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   992 fixsome to patch .thy and .ML sources automatically;
   993 
   994   select_equality  -> some_equality
   995   select_eq_Ex     -> some_eq_ex
   996   selectI2EX       -> someI2_ex
   997   selectI2         -> someI2
   998   selectI          -> someI
   999   select1_equality -> some1_equality
  1000   Eps_sym_eq       -> some_sym_eq_trivial
  1001   Eps_eq           -> some_eq_trivial
  1002 
  1003 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
  1004 
  1005 * HOL: removed obsolete theorem binding expand_if (refer to split_if
  1006 instead);
  1007 
  1008 * HOL: the recursion equations generated by 'recdef' are now called
  1009 f.simps instead of f.rules;
  1010 
  1011 * HOL: qed_spec_mp now also handles bounded ALL as well;
  1012 
  1013 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  1014 sometimes be needed;
  1015 
  1016 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  1017 
  1018 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  1019 
  1020 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  1021 product is now "<*>" instead of "Times"; the lexicographic product is
  1022 now "<*lex*>" instead of "**";
  1023 
  1024 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  1025 of main HOL, but was unused); better use HOL's datatype package;
  1026 
  1027 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  1028 the old syntax may be recovered as follows:
  1029 
  1030   syntax (symbols)
  1031     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  1032       (infixl "\\<oplus>" 100)
  1033 
  1034 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1035 
  1036 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1037 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1038 internally;
  1039 
  1040 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1041 changed from A/r to A//r;
  1042 
  1043 * ZF: new treatment of arithmetic (nat & int) may break some old
  1044 proofs;
  1045 
  1046 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1047 rulify -> rule_format, elimify -> elim_format, ...);
  1048 
  1049 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1050 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1051 should have to change intro!! to intro? only); replaced "delrule" by
  1052 "rule del";
  1053 
  1054 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1055 
  1056 * Provers: strengthened force_tac by using new first_best_tac;
  1057 
  1058 * LaTeX document preparation: several changes of isabelle.sty (see
  1059 lib/texinputs);
  1060 
  1061 
  1062 *** Document preparation ***
  1063 
  1064 * formal comments (text blocks etc.) in new-style theories may now
  1065 contain antiquotations of thm/prop/term/typ/text to be presented
  1066 according to latex print mode; concrete syntax is like this:
  1067 @{term[show_types] "f(x) = a + x"};
  1068 
  1069 * isatool mkdir provides easy setup of Isabelle session directories,
  1070 including proper document sources;
  1071 
  1072 * generated LaTeX sources are now deleted after successful run
  1073 (isatool document -c); may retain a copy somewhere else via -D option
  1074 of isatool usedir;
  1075 
  1076 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1077 style files, achieving self-contained LaTeX sources and simplifying
  1078 LaTeX debugging;
  1079 
  1080 * old-style theories now produce (crude) LaTeX output as well;
  1081 
  1082 * browser info session directories are now self-contained (may be put
  1083 on WWW server seperately); improved graphs of nested sessions; removed
  1084 graph for 'all sessions';
  1085 
  1086 * several improvements in isabelle style files; \isabellestyle{it}
  1087 produces fake math mode output; \isamarkupheader is now \section by
  1088 default; see lib/texinputs/isabelle.sty etc.;
  1089 
  1090 
  1091 *** Isar ***
  1092 
  1093 * Isar/Pure: local results and corresponding term bindings are now
  1094 subject to Hindley-Milner polymorphism (similar to ML); this
  1095 accommodates incremental type-inference very nicely;
  1096 
  1097 * Isar/Pure: new derived language element 'obtain' supports
  1098 generalized existence reasoning;
  1099 
  1100 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1101 support accumulation of results, without applying any rules yet;
  1102 useful to collect intermediate results without explicit name
  1103 references, and for use with transitivity rules with more than 2
  1104 premises;
  1105 
  1106 * Isar/Pure: scalable support for case-analysis type proofs: new
  1107 'case' language element refers to local contexts symbolically, as
  1108 produced by certain proof methods; internally, case names are attached
  1109 to theorems as "tags";
  1110 
  1111 * Isar/Pure: theory command 'hide' removes declarations from
  1112 class/type/const name spaces;
  1113 
  1114 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1115 indicate potential overloading;
  1116 
  1117 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1118 
  1119 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1120 "{a,b,c}" instead of {a,b,c};
  1121 
  1122 * Isar/Pure now provides its own version of intro/elim/dest
  1123 attributes; useful for building new logics, but beware of confusion
  1124 with the version in Provers/classical;
  1125 
  1126 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1127 case name 'antecedent';
  1128 
  1129 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1130 to the current context is now done automatically);
  1131 
  1132 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1133 for definining proof methods in ML;
  1134 
  1135 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1136 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1137 most cases, one should have to change intro!! to intro? only);
  1138 replaced "delrule" by "rule del";
  1139 
  1140 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1141 'symmetric' attribute (the latter supercedes [RS sym]);
  1142 
  1143 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1144 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1145 well (including splits);
  1146 
  1147 * Isar/Provers: Simplifier and Classical methods now support all kind
  1148 of modifiers used in the past, including 'cong', 'iff', etc.
  1149 
  1150 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1151 of Simplifier and Classical reasoner);
  1152 
  1153 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1154 now support named cases; major packages (inductive, datatype, primrec,
  1155 recdef) support case names and properly name parameters;
  1156 
  1157 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1158 monotonicity conditions are extracted to be proven at end of
  1159 calculations;
  1160 
  1161 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1162 method anyway;
  1163 
  1164 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1165 split_if split_if_asm; datatype package provides theorems foo.splits =
  1166 foo.split foo.split_asm for each datatype;
  1167 
  1168 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1169 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1170 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1171 use "(cases (simplified))" method in proper proof texts);
  1172 
  1173 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1174 
  1175 * Isar: names of theorems etc. may be natural numbers as well;
  1176 
  1177 * Isar: 'pr' command: optional arguments for goals_limit and
  1178 ProofContext.prems_limit; no longer prints theory contexts, but only
  1179 proof states;
  1180 
  1181 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1182 additional print modes to be specified; e.g. "pr(latex)" will print
  1183 proof state according to the Isabelle LaTeX style;
  1184 
  1185 * Isar: improved support for emulating tactic scripts, including proof
  1186 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1187 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1188 (for HOL datatypes);
  1189 
  1190 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1191 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1192 'proof method scripts' have to be in depth-first order;
  1193 
  1194 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1195 
  1196 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1197 should instead use individual commands for printing items
  1198 (print_commands, print_methods etc.);
  1199 
  1200 * Isar: added 'nothing' --- the empty list of theorems;
  1201 
  1202 
  1203 *** HOL ***
  1204 
  1205 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1206 corresponding virtual machine and a specification of its bytecode
  1207 verifier and a lightweight bytecode verifier, including proofs of
  1208 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1209 Cornelia Pusch (see also the homepage of project Bali at
  1210 http://isabelle.in.tum.de/Bali/);
  1211 
  1212 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1213 Clemens Ballarin;
  1214 
  1215 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1216 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1217 Rasmussen;
  1218 
  1219 * HOL/Lattice: fundamental concepts of lattice theory and order
  1220 structures, including duals, properties of bounds versus algebraic
  1221 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1222 Theorem for complete lattices etc.; may also serve as a demonstration
  1223 for abstract algebraic reasoning using axiomatic type classes, and
  1224 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1225 
  1226 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1227 von Oheimb;
  1228 
  1229 * HOL/IMPP: extension of IMP with local variables and mutually
  1230 recursive procedures, by David von Oheimb;
  1231 
  1232 * HOL/Lambda: converted into new-style theory and document;
  1233 
  1234 * HOL/ex/Multiquote: example of multiple nested quotations and
  1235 anti-quotations -- basically a generalized version of de-Bruijn
  1236 representation; very useful in avoiding lifting of operations;
  1237 
  1238 * HOL/record: added general record equality rule to simpset; fixed
  1239 select-update simplification procedure to handle extended records as
  1240 well; admit "r" as field name;
  1241 
  1242 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1243 other numeric types and also as the identity of groups, rings, etc.;
  1244 
  1245 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1246 Types nat and int belong to this axclass;
  1247 
  1248 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1249    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1250    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1251   two terms #m*u and #n*u are replaced by #(m+n)*u
  1252     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1253   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1254     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1255 
  1256 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1257 powerful prover for predicate logic but knows nothing of clasets; see
  1258 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1259 
  1260 * HOL: new version of "case_tac" subsumes both boolean case split and
  1261 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1262 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1263 
  1264 * HOL: simplification no longer dives into case-expressions: only the
  1265 selector expression is simplified, but not the remaining arms; to
  1266 enable full simplification of case-expressions for datatype t, you may
  1267 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1268 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1269 
  1270 * HOL/recdef: the recursion equations generated by 'recdef' for
  1271 function 'f' are now called f.simps instead of f.rules; if all
  1272 termination conditions are proved automatically, these simplification
  1273 rules are added to the simpset, as in primrec; rules may be named
  1274 individually as well, resulting in a separate list of theorems for
  1275 each equation;
  1276 
  1277 * HOL/While is a new theory that provides a while-combinator. It
  1278 permits the definition of tail-recursive functions without the
  1279 provision of a termination measure. The latter is necessary once the
  1280 invariant proof rule for while is applied.
  1281 
  1282 * HOL: new (overloaded) notation for the set of elements below/above
  1283 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1284 
  1285 * HOL: theorems impI, allI, ballI bound as "strip";
  1286 
  1287 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1288 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1289 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1290 
  1291 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1292 
  1293 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1294 main HOL, but was unused);
  1295 
  1296 * HOL: fewer consts declared as global (e.g. have to refer to
  1297 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1298 
  1299 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1300 in case of overlap with user translations (e.g. judgements over
  1301 tuples); (note that the underlying logical represenation is still
  1302 bogus);
  1303 
  1304 
  1305 *** ZF ***
  1306 
  1307 * ZF: simplification automatically cancels common terms in arithmetic
  1308 expressions over nat and int;
  1309 
  1310 * ZF: new treatment of nat to minimize type-checking: all operators
  1311 coerce their operands to a natural number using the function natify,
  1312 making the algebraic laws unconditional;
  1313 
  1314 * ZF: as above, for int: operators coerce their operands to an integer
  1315 using the function intify;
  1316 
  1317 * ZF: the integer library now contains many of the usual laws for the
  1318 orderings, including $<=, and monotonicity laws for $+ and $*;
  1319 
  1320 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1321 simplification;
  1322 
  1323 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1324 to the simplifier and classical reasoner simultaneously;
  1325 
  1326 
  1327 *** General ***
  1328 
  1329 * Provers: blast_tac now handles actual object-logic rules as
  1330 assumptions; note that auto_tac uses blast_tac internally as well;
  1331 
  1332 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1333 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1334 
  1335 * Provers: delrules now handles destruct rules as well (no longer need
  1336 explicit make_elim);
  1337 
  1338 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1339   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1340 use instead the strong form,
  1341   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1342 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1343 from destruct-rules;
  1344 
  1345 * Provers: Simplifier.easy_setup provides a fast path to basic
  1346 Simplifier setup for new object-logics;
  1347 
  1348 * Pure: AST translation rules no longer require constant head on LHS;
  1349 
  1350 * Pure: improved name spaces: ambiguous output is qualified; support
  1351 for hiding of names;
  1352 
  1353 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1354 XSYMBOL_HOME; no longer need to do manual configuration in most
  1355 situations;
  1356 
  1357 * system: compression of ML heaps images may now be controlled via -c
  1358 option of isabelle and isatool usedir (currently only observed by
  1359 Poly/ML);
  1360 
  1361 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1362 useful for remote X11);
  1363 
  1364 * system: provide TAGS file for Isabelle sources;
  1365 
  1366 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1367 order;
  1368 
  1369 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1370 timing flag supersedes proof_timing and Toplevel.trace;
  1371 
  1372 * ML: new combinators |>> and |>>> for incremental transformations
  1373 with secondary results (e.g. certain theory extensions):
  1374 
  1375 * ML: PureThy.add_defs gets additional argument to indicate potential
  1376 overloading (usually false);
  1377 
  1378 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1379 results;
  1380 
  1381 
  1382 
  1383 New in Isabelle99 (October 1999)
  1384 --------------------------------
  1385 
  1386 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1387 
  1388 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1389 are no longer simplified.  (This allows the simplifier to unfold recursive
  1390 functional programs.)  To restore the old behaviour, declare
  1391 
  1392     Delcongs [if_weak_cong];
  1393 
  1394 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1395 complement;
  1396 
  1397 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1398 
  1399 * HOL/datatype: mutual_induct_tac no longer exists --
  1400   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1401 
  1402 * HOL/typedef: fixed type inference for representing set; type
  1403 arguments now have to occur explicitly on the rhs as type constraints;
  1404 
  1405 * ZF: The con_defs part of an inductive definition may no longer refer
  1406 to constants declared in the same theory;
  1407 
  1408 * HOL, ZF: the function mk_cases, generated by the inductive
  1409 definition package, has lost an argument.  To simplify its result, it
  1410 uses the default simpset instead of a supplied list of theorems.
  1411 
  1412 * HOL/List: the constructors of type list are now Nil and Cons;
  1413 
  1414 * Simplifier: the type of the infix ML functions
  1415         setSSolver addSSolver setSolver addSolver
  1416 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1417 for packaging solvers. A solver is created via
  1418         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1419 where the string argument is only a comment.
  1420 
  1421 
  1422 *** Proof tools ***
  1423 
  1424 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1425 decision procedure for linear arithmetic. Currently it is used for
  1426 types `nat', `int', and `real' in HOL (see below); it can, should and
  1427 will be instantiated for other types and logics as well.
  1428 
  1429 * The simplifier now accepts rewrite rules with flexible heads, eg
  1430      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1431   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1432   matching.
  1433 
  1434 
  1435 *** General ***
  1436 
  1437 * New Isabelle/Isar subsystem provides an alternative to traditional
  1438 tactical theorem proving; together with the ProofGeneral/isar user
  1439 interface it offers an interactive environment for developing human
  1440 readable proof documents (Isar == Intelligible semi-automated
  1441 reasoning); for further information see isatool doc isar-ref,
  1442 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1443 
  1444 * improved and simplified presentation of theories: better HTML markup
  1445 (including colors), graph views in several sizes; isatool usedir now
  1446 provides a proper interface for user theories (via -P option); actual
  1447 document preparation based on (PDF)LaTeX is available as well (for
  1448 new-style theories only); see isatool doc system for more information;
  1449 
  1450 * native support for Proof General, both for classic Isabelle and
  1451 Isabelle/Isar;
  1452 
  1453 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1454 using the graph browser tool;
  1455 
  1456 * Isabelle manuals now also available as PDF;
  1457 
  1458 * theory loader rewritten from scratch (may not be fully
  1459 bug-compatible); old loadpath variable has been replaced by show_path,
  1460 add_path, del_path, reset_path functions; new operations such as
  1461 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1462 isatool doc ref);
  1463 
  1464 * improved isatool install: option -k creates KDE application icon,
  1465 option -p DIR installs standalone binaries;
  1466 
  1467 * added ML_PLATFORM setting (useful for cross-platform installations);
  1468 more robust handling of platform specific ML images for SML/NJ;
  1469 
  1470 * the settings environment is now statically scoped, i.e. it is never
  1471 created again in sub-processes invoked from isabelle, isatool, or
  1472 Isabelle;
  1473 
  1474 * path element specification '~~' refers to '$ISABELLE_HOME';
  1475 
  1476 * in locales, the "assumes" and "defines" parts may be omitted if
  1477 empty;
  1478 
  1479 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1480 long arrows);
  1481 
  1482 * new print_mode "HTML";
  1483 
  1484 * new flag show_tags controls display of tags of theorems (which are
  1485 basically just comments that may be attached by some tools);
  1486 
  1487 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1488 mode and goal output format:
  1489 
  1490 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1491 244c244
  1492 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1493 ---
  1494 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1495 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1496 181c181
  1497 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1498 ---
  1499 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1500 
  1501 * function bind_thms stores lists of theorems (cf. bind_thm);
  1502 
  1503 * new shorthand tactics ftac, eatac, datac, fatac;
  1504 
  1505 * qed (and friends) now accept "" as result name; in that case the
  1506 theorem is not stored, but proper checks and presentation of the
  1507 result still apply;
  1508 
  1509 * theorem database now also indexes constants "Trueprop", "all",
  1510 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1511 
  1512 
  1513 *** HOL ***
  1514 
  1515 ** HOL arithmetic **
  1516 
  1517 * There are now decision procedures for linear arithmetic over nat and
  1518 int:
  1519 
  1520 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1521 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1522 are treated as atomic; subformulae not involving type `nat' or `int'
  1523 are ignored; quantified subformulae are ignored unless they are
  1524 positive universal or negative existential. The tactic has to be
  1525 invoked by hand and can be a little bit slow. In particular, the
  1526 running time is exponential in the number of occurrences of `min' and
  1527 `max', and `-' on `nat'.
  1528 
  1529 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1530 (negated) (in)equalities among the premises and the conclusion into
  1531 account (i.e. no compound formulae) and does not know about `min' and
  1532 `max', and `-' on `nat'. It is fast and is used automatically by the
  1533 simplifier.
  1534 
  1535 NB: At the moment, these decision procedures do not cope with mixed
  1536 nat/int formulae where the two parts interact, such as `m < n ==>
  1537 int(m) < int(n)'.
  1538 
  1539 * HOL/Numeral provides a generic theory of numerals (encoded
  1540 efficiently as bit strings); setup for types nat/int/real is in place;
  1541 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1542 int, existing theories and proof scripts may require a few additional
  1543 type constraints;
  1544 
  1545 * integer division and remainder can now be performed on constant
  1546 arguments;
  1547 
  1548 * many properties of integer multiplication, division and remainder
  1549 are now available;
  1550 
  1551 * An interface to the Stanford Validity Checker (SVC) is available through the
  1552 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1553 are proved automatically.  SVC must be installed separately, and its results
  1554 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1555 invocation of the underlying oracle).  For SVC see
  1556   http://verify.stanford.edu/SVC
  1557 
  1558 * IsaMakefile: the HOL-Real target now builds an actual image;
  1559 
  1560 
  1561 ** HOL misc **
  1562 
  1563 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1564 (in Isabelle/Isar) -- by Gertrud Bauer;
  1565 
  1566 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1567 analysis for assembly languages with subtypes;
  1568 
  1569 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1570 -- avoids syntactic ambiguities and treats state, transition, and
  1571 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1572 changed syntax and (many) tactics;
  1573 
  1574 * HOL/inductive: Now also handles more general introduction rules such
  1575   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1576   theorems are now maintained within the theory (maintained via the
  1577   "mono" attribute);
  1578 
  1579 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1580   (using function types) such as
  1581 
  1582   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1583 
  1584 * HOL/record: record_simproc (part of the default simpset) takes care
  1585 of selectors applied to updated records; record_split_tac is no longer
  1586 part of the default claset; update_defs may now be removed from the
  1587 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1588 
  1589   claset_ref () := claset() addSWrapper record_split_wrapper;
  1590   Delsimprocs [record_simproc]
  1591 
  1592 * HOL/typedef: fixed type inference for representing set; type
  1593 arguments now have to occur explicitly on the rhs as type constraints;
  1594 
  1595 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1596 names rather than an ML expression;
  1597 
  1598 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1599 supplied later.  Program schemes can be defined, such as
  1600     "While B C s = (if B s then While B C (C s) else s)"
  1601 where the well-founded relation can be chosen after B and C have been given.
  1602 
  1603 * HOL/List: the constructors of type list are now Nil and Cons;
  1604 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1605 course, ML tools referring to List.list.op # etc. have to be adapted;
  1606 
  1607 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1608 disabled by default; run isabelle with option -m HOL to get back to
  1609 the original Gordon/HOL-style output;
  1610 
  1611 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1612 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1613 
  1614 * HOL basic syntax simplified (more orthogonal): all variants of
  1615 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1616 Eps operator is provided as well: "SOME x. P[x]";
  1617 
  1618 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1619 
  1620 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1621 thus available for user theories;
  1622 
  1623 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1624 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1625 time;
  1626 
  1627 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1628 several times and then mp;
  1629 
  1630 
  1631 *** LK ***
  1632 
  1633 * the notation <<...>> is now available as a notation for sequences of
  1634 formulas;
  1635 
  1636 * the simplifier is now installed
  1637 
  1638 * the axiom system has been generalized (thanks to Soren Heilmann)
  1639 
  1640 * the classical reasoner now has a default rule database
  1641 
  1642 
  1643 *** ZF ***
  1644 
  1645 * new primrec section allows primitive recursive functions to be given
  1646 directly (as in HOL) over datatypes and the natural numbers;
  1647 
  1648 * new tactics induct_tac and exhaust_tac for induction (or case
  1649 analysis) over datatypes and the natural numbers;
  1650 
  1651 * the datatype declaration of type T now defines the recursor T_rec;
  1652 
  1653 * simplification automatically does freeness reasoning for datatype
  1654 constructors;
  1655 
  1656 * automatic type-inference, with AddTCs command to insert new
  1657 type-checking rules;
  1658 
  1659 * datatype introduction rules are now added as Safe Introduction rules
  1660 to the claset;
  1661 
  1662 * the syntax "if P then x else y" is now available in addition to
  1663 if(P,x,y);
  1664 
  1665 
  1666 *** Internal programming interfaces ***
  1667 
  1668 * tuned simplifier trace output; new flag debug_simp;
  1669 
  1670 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1671 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1672 
  1673 * AxClass.axclass_tac lost the theory argument;
  1674 
  1675 * tuned current_goals_markers semantics: begin / end goal avoids
  1676 printing empty lines;
  1677 
  1678 * removed prs and prs_fn hook, which was broken because it did not
  1679 include \n in its semantics, forcing writeln to add one
  1680 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1681 string -> unit if you really want to output text without newline;
  1682 
  1683 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1684 plain output, interface builders may have to enable 'isabelle_font'
  1685 mode to get Isabelle font glyphs as before;
  1686 
  1687 * refined token_translation interface; INCOMPATIBILITY: output length
  1688 now of type real instead of int;
  1689 
  1690 * theory loader actions may be traced via new ThyInfo.add_hook
  1691 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1692 your own database of information attached to *whole* theories -- as
  1693 opposed to intra-theory data slots offered via TheoryDataFun;
  1694 
  1695 * proper handling of dangling sort hypotheses (at last!);
  1696 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1697 extra sort hypotheses that can be witnessed from the type signature;
  1698 the force_strip_shyps flag is gone, any remaining shyps are simply
  1699 left in the theorem (with a warning issued by strip_shyps_warning);
  1700 
  1701 
  1702 
  1703 New in Isabelle98-1 (October 1998)
  1704 ----------------------------------
  1705 
  1706 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1707 
  1708 * several changes of automated proof tools;
  1709 
  1710 * HOL: major changes to the inductive and datatype packages, including
  1711 some minor incompatibilities of theory syntax;
  1712 
  1713 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1714 called `inj_on';
  1715 
  1716 * HOL: removed duplicate thms in Arith:
  1717   less_imp_add_less  should be replaced by  trans_less_add1
  1718   le_imp_add_le      should be replaced by  trans_le_add1
  1719 
  1720 * HOL: unary minus is now overloaded (new type constraints may be
  1721 required);
  1722 
  1723 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1724 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1725 now taken as an integer constant.
  1726 
  1727 * Pure: ML function 'theory_of' renamed to 'theory';
  1728 
  1729 
  1730 *** Proof tools ***
  1731 
  1732 * Simplifier:
  1733   1. Asm_full_simp_tac is now more aggressive.
  1734      1. It will sometimes reorient premises if that increases their power to
  1735         simplify.
  1736      2. It does no longer proceed strictly from left to right but may also
  1737         rotate premises to achieve further simplification.
  1738      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1739      old Asm_full_simp_tac in that it does not rotate premises.
  1740   2. The simplifier now knows a little bit about nat-arithmetic.
  1741 
  1742 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1743 allows for selected deletion of wrappers, by introduction of names for
  1744 wrapper functionals.  This implies that addbefore, addSbefore,
  1745 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1746 and that adding two tactics with the same name overwrites the first
  1747 one (emitting a warning).
  1748   type wrapper = (int -> tactic) -> (int -> tactic)
  1749   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1750   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1751   delWrapper, delSWrapper: claset *  string            -> claset
  1752   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1753 
  1754 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1755 semantics; addbefore now affects only the unsafe part of step_tac
  1756 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1757 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1758 by Force_tac;
  1759 
  1760 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1761 compWrapper; added safe wrapper (and access functions for it);
  1762 
  1763 * HOL/split_all_tac is now much faster and fails if there is nothing
  1764 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1765 and the names of the automatically generated variables have changed.
  1766 split_all_tac has moved within claset() from unsafe wrappers to safe
  1767 wrappers, which means that !!-bound variables are split much more
  1768 aggressively, and safe_tac and clarify_tac now split such variables.
  1769 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1770 Note: the same holds for record_split_tac, which does the job of
  1771 split_all_tac for record fields.
  1772 
  1773 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1774 permanently to the default simpset using Addsplits just like
  1775 Addsimps. They can be removed via Delsplits just like
  1776 Delsimps. Lower-case versions are also available.
  1777 
  1778 * HOL/Simplifier: The rule split_if is now part of the default
  1779 simpset. This means that the simplifier will eliminate all occurrences
  1780 of if-then-else in the conclusion of a goal. To prevent this, you can
  1781 either remove split_if completely from the default simpset by
  1782 `Delsplits [split_if]' or remove it in a specific call of the
  1783 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1784 other case splitting rules to/from the default simpset: every datatype
  1785 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1786 t is the name of the datatype).
  1787 
  1788 * Classical reasoner / Simplifier combination: new force_tac (and
  1789 derivatives Force_tac, force) combines rewriting and classical
  1790 reasoning (and whatever other tools) similarly to auto_tac, but is
  1791 aimed to solve the given subgoal completely.
  1792 
  1793 
  1794 *** General ***
  1795 
  1796 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1797 and `goalw': the theory is no longer needed as an explicit argument -
  1798 the current theory context is used; assumptions are no longer returned
  1799 at the ML-level unless one of them starts with ==> or !!; it is
  1800 recommended to convert to these new commands using isatool fixgoal
  1801 (backup your sources first!);
  1802 
  1803 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1804 the current theory context, and 'theory' to lookup stored theories;
  1805 
  1806 * new theory section 'locale' for declaring constants, assumptions and
  1807 definitions that have local scope;
  1808 
  1809 * new theory section 'nonterminals' for purely syntactic types;
  1810 
  1811 * new theory section 'setup' for generic ML setup functions
  1812 (e.g. package initialization);
  1813 
  1814 * the distribution now includes Isabelle icons: see
  1815 lib/logo/isabelle-{small,tiny}.xpm;
  1816 
  1817 * isatool install - install binaries with absolute references to
  1818 ISABELLE_HOME/bin;
  1819 
  1820 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1821 
  1822 * print mode 'emacs' reserved for Isamode;
  1823 
  1824 * support multiple print (ast) translations per constant name;
  1825 
  1826 * theorems involving oracles are now printed with a suffixed [!];
  1827 
  1828 
  1829 *** HOL ***
  1830 
  1831 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1832 
  1833 * HOL/inductive package reorganized and improved: now supports mutual
  1834 definitions such as
  1835 
  1836   inductive EVEN ODD
  1837     intrs
  1838       null "0 : EVEN"
  1839       oddI "n : EVEN ==> Suc n : ODD"
  1840       evenI "n : ODD ==> Suc n : EVEN"
  1841 
  1842 new theorem list "elims" contains an elimination rule for each of the
  1843 recursive sets; inductive definitions now handle disjunctive premises
  1844 correctly (also ZF);
  1845 
  1846 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1847 "mutual_induct" no longer exists - the induction rule is always
  1848 contained in "induct";
  1849 
  1850 
  1851 * HOL/datatype package re-implemented and greatly improved: now
  1852 supports mutually recursive datatypes such as
  1853 
  1854   datatype
  1855     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1856             | SUM ('a aexp) ('a aexp)
  1857             | DIFF ('a aexp) ('a aexp)
  1858             | NUM 'a
  1859   and
  1860     'a bexp = LESS ('a aexp) ('a aexp)
  1861             | AND ('a bexp) ('a bexp)
  1862             | OR ('a bexp) ('a bexp)
  1863 
  1864 as well as indirectly recursive datatypes such as
  1865 
  1866   datatype
  1867     ('a, 'b) term = Var 'a
  1868                   | App 'b ((('a, 'b) term) list)
  1869 
  1870 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1871 induction on mutually / indirectly recursive datatypes.
  1872 
  1873 Primrec equations are now stored in theory and can be accessed via
  1874 <function_name>.simps.
  1875 
  1876 INCOMPATIBILITIES:
  1877 
  1878   - Theories using datatypes must now have theory Datatype as an
  1879     ancestor.
  1880   - The specific <typename>.induct_tac no longer exists - use the
  1881     generic induct_tac instead.
  1882   - natE has been renamed to nat.exhaust - use exhaust_tac
  1883     instead of res_inst_tac ... natE. Note that the variable
  1884     names in nat.exhaust differ from the names in natE, this
  1885     may cause some "fragile" proofs to fail.
  1886   - The theorems split_<typename>_case and split_<typename>_case_asm
  1887     have been renamed to <typename>.split and <typename>.split_asm.
  1888   - Since default sorts of type variables are now handled correctly,
  1889     some datatype definitions may have to be annotated with explicit
  1890     sort constraints.
  1891   - Primrec definitions no longer require function name and type
  1892     of recursive argument.
  1893 
  1894 Consider using isatool fixdatatype to adapt your theories and proof
  1895 scripts to the new package (backup your sources first!).
  1896 
  1897 
  1898 * HOL/record package: considerably improved implementation; now
  1899 includes concrete syntax for record types, terms, updates; theorems
  1900 for surjective pairing and splitting !!-bound record variables; proof
  1901 support is as follows:
  1902 
  1903   1) standard conversions (selectors or updates applied to record
  1904 constructor terms) are part of the standard simpset;
  1905 
  1906   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1907 made part of standard simpset and claset via addIffs;
  1908 
  1909   3) a tactic for record field splitting (record_split_tac) is part of
  1910 the standard claset (addSWrapper);
  1911 
  1912 To get a better idea about these rules you may retrieve them via
  1913 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1914 the name of your record type.
  1915 
  1916 The split tactic 3) conceptually simplifies by the following rule:
  1917 
  1918   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1919 
  1920 Thus any record variable that is bound by meta-all will automatically
  1921 blow up into some record constructor term, consequently the
  1922 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1923 solve record problems automatically.
  1924 
  1925 
  1926 * reorganized the main HOL image: HOL/Integ and String loaded by
  1927 default; theory Main includes everything;
  1928 
  1929 * automatic simplification of integer sums and comparisons, using cancellation;
  1930 
  1931 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1932 
  1933 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1934 
  1935 * many new identities for unions, intersections, set difference, etc.;
  1936 
  1937 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1938 called split_if, split_split, split_sum_case and split_nat_case (to go
  1939 with add/delsplits);
  1940 
  1941 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1942 (?x::unit) = (); this is made part of the default simpset, which COULD
  1943 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1944 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1945 unit_abs_eta_conv is added in order to counter the effect of
  1946 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1947 %u.f();
  1948 
  1949 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1950 makes more sense);
  1951 
  1952 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1953   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1954   disjointness reasoning but breaking a few old proofs.
  1955 
  1956 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1957 to 'converse' from 'inverse' (for compatibility with ZF and some
  1958 literature);
  1959 
  1960 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1961 the well-founded relation;
  1962 
  1963 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1964     Compl A.  The "Compl" syntax remains available as input syntax for this
  1965     release ONLY.
  1966 
  1967 * HOL/Update: new theory of function updates:
  1968     f(a:=b) == %x. if x=a then b else f x
  1969 may also be iterated as in f(a:=b,c:=d,...);
  1970 
  1971 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1972 
  1973 * HOL/List:
  1974   - new function list_update written xs[i:=v] that updates the i-th
  1975     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1976   - new function `upt' written [i..j(] which generates the list
  1977     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1978     bound write [i..j], which is a shorthand for [i..j+1(].
  1979   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1980 
  1981 * HOL/Arith:
  1982   - removed 'pred' (predecessor) function;
  1983   - generalized some theorems about n-1;
  1984   - many new laws about "div" and "mod";
  1985   - new laws about greatest common divisors (see theory ex/Primes);
  1986 
  1987 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1988 instead of "inverse";
  1989 
  1990 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1991   of the multiset ordering;
  1992 
  1993 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1994   (not included by default);
  1995 
  1996 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1997 
  1998 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1999   programs, i.e. different program variables may have different types.
  2000 
  2001 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2002   [previously, this check worked only if the rewrite rule was unconditional]
  2003   Now rew can involve either definitions or equalities (either == or =).
  2004 
  2005 
  2006 *** ZF ***
  2007 
  2008 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  2009   only the theorems proved on ZF.ML;
  2010 
  2011 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2012   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2013   disjointness reasoning but breaking a few old proofs.
  2014 
  2015 * ZF/Update: new theory of function updates
  2016     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  2017   may also be iterated as in f(a:=b,c:=d,...);
  2018 
  2019 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  2020 
  2021 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2022   [previously, this check worked only if the rewrite rule was unconditional]
  2023   Now rew can involve either definitions or equalities (either == or =).
  2024 
  2025 * case_tac provided for compatibility with HOL
  2026     (like the old excluded_middle_tac, but with subgoals swapped)
  2027 
  2028 
  2029 *** Internal programming interfaces ***
  2030 
  2031 * Pure: several new basic modules made available for general use, see
  2032 also src/Pure/README;
  2033 
  2034 * improved the theory data mechanism to support encapsulation (data
  2035 kind name replaced by private Object.kind, acting as authorization
  2036 key); new type-safe user interface via functor TheoryDataFun; generic
  2037 print_data function becomes basically useless;
  2038 
  2039 * removed global_names compatibility flag -- all theory declarations
  2040 are qualified by default;
  2041 
  2042 * module Pure/Syntax now offers quote / antiquote translation
  2043 functions (useful for Hoare logic etc. with implicit dependencies);
  2044 see HOL/ex/Antiquote for an example use;
  2045 
  2046 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2047 cterm -> thm;
  2048 
  2049 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2050 subgoal;
  2051 
  2052 * Display.print_goals function moved to Locale.print_goals;
  2053 
  2054 * standard print function for goals supports current_goals_markers
  2055 variable for marking begin of proof, end of proof, start of goal; the
  2056 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2057 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2058 for example;
  2059 
  2060 
  2061 
  2062 New in Isabelle98 (January 1998)
  2063 --------------------------------
  2064 
  2065 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2066 
  2067 * changed lexical syntax of terms / types: dots made part of long
  2068 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2069 
  2070 * simpset (and claset) reference variable replaced by functions
  2071 simpset / simpset_ref;
  2072 
  2073 * no longer supports theory aliases (via merge) and non-trivial
  2074 implicit merge of thms' signatures;
  2075 
  2076 * most internal names of constants changed due to qualified names;
  2077 
  2078 * changed Pure/Sequence interface (see Pure/seq.ML);
  2079 
  2080 
  2081 *** General Changes ***
  2082 
  2083 * hierachically structured name spaces (for consts, types, axms, thms
  2084 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2085 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2086 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2087 long_names for fully qualified output names; NOTE: ML programs
  2088 (special tactics, packages etc.) referring to internal names may have
  2089 to be adapted to cope with fully qualified names; in case of severe
  2090 backward campatibility problems try setting 'global_names' at compile
  2091 time to have enrything declared within a flat name space; one may also
  2092 fine tune name declarations in theories via the 'global' and 'local'
  2093 section;
  2094 
  2095 * reimplemented the implicit simpset and claset using the new anytype
  2096 data filed in signatures; references simpset:simpset ref etc. are
  2097 replaced by functions simpset:unit->simpset and
  2098 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2099 to patch your ML files accordingly;
  2100 
  2101 * HTML output now includes theory graph data for display with Java
  2102 applet or isatool browser; data generated automatically via isatool
  2103 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2104 
  2105 * defs may now be conditional; improved rewrite_goals_tac to handle
  2106 conditional equations;
  2107 
  2108 * defs now admits additional type arguments, using TYPE('a) syntax;
  2109 
  2110 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2111 creates a new theory node; implicit merge of thms' signatures is
  2112 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2113 transfer:theory->thm->thm in (rare) cases;
  2114 
  2115 * improved handling of draft signatures / theories; draft thms (and
  2116 ctyps, cterms) are automatically promoted to real ones;
  2117 
  2118 * slightly changed interfaces for oracles: admit many per theory, named
  2119 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2120 
  2121 * print_goals: optional output of const types (set show_consts and
  2122 show_types);
  2123 
  2124 * improved output of warnings (###) and errors (***);
  2125 
  2126 * subgoal_tac displays a warning if the new subgoal has type variables;
  2127 
  2128 * removed old README and Makefiles;
  2129 
  2130 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2131 
  2132 * removed obsolete init_pps and init_database;
  2133 
  2134 * deleted the obsolete tactical STATE, which was declared by
  2135     fun STATE tacfun st = tacfun st st;
  2136 
  2137 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2138 (which abbreviates $HOME);
  2139 
  2140 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2141 use isatool fixseq to adapt your ML programs (this works for fully
  2142 qualified references to the Sequence structure only!);
  2143 
  2144 * use_thy no longer requires writable current directory; it always
  2145 reloads .ML *and* .thy file, if either one is out of date;
  2146 
  2147 
  2148 *** Classical Reasoner ***
  2149 
  2150 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2151 tactics that use classical reasoning to simplify a subgoal without
  2152 splitting it into several subgoals;
  2153 
  2154 * Safe_tac: like safe_tac but uses the default claset;
  2155 
  2156 
  2157 *** Simplifier ***
  2158 
  2159 * added simplification meta rules:
  2160     (asm_)(full_)simplify: simpset -> thm -> thm;
  2161 
  2162 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2163 logics (again);
  2164 
  2165 * added prems argument to simplification procedures;
  2166 
  2167 * HOL, FOL, ZF: added infix function `addsplits':
  2168   instead of `<simpset> setloop (split_tac <thms>)'
  2169   you can simply write `<simpset> addsplits <thms>'
  2170 
  2171 
  2172 *** Syntax ***
  2173 
  2174 * TYPE('a) syntax for type reflection terms;
  2175 
  2176 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2177 
  2178 * pretty printer: changed order of mixfix annotation preference (again!);
  2179 
  2180 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2181 
  2182 
  2183 *** HOL ***
  2184 
  2185 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2186   with `addloop' of the simplifier to faciliate case splitting in premises.
  2187 
  2188 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2189 
  2190 * HOL/Auth: new protocol proofs including some for the Internet
  2191   protocol TLS;
  2192 
  2193 * HOL/Map: new theory of `maps' a la VDM;
  2194 
  2195 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2196 cancelling out common nat summands from =, <, <= (in)equalities, or
  2197 differences; simplification procedures nat_cancel_factor for
  2198 cancelling common factor from =, <, <= (in)equalities over natural
  2199 sums; nat_cancel contains both kinds of procedures, it is installed by
  2200 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2201 
  2202 * HOL/simplifier: terms of the form
  2203   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2204   are rewritten to
  2205   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2206   and those of the form
  2207   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2208   are rewritten to
  2209   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2210 
  2211 * HOL/datatype
  2212   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2213 
  2214   P(t_case f1 ... fn x) =
  2215      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2216         ...
  2217        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2218      )
  2219 
  2220   and a theorem `split_t_case_asm' of the form
  2221 
  2222   P(t_case f1 ... fn x) =
  2223     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2224         ...
  2225        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2226      )
  2227   which can be added to a simpset via `addsplits'. The existing theorems
  2228   expand_list_case and expand_option_case have been renamed to
  2229   split_list_case and split_option_case.
  2230 
  2231 * HOL/Arithmetic:
  2232   - `pred n' is automatically converted to `n-1'.
  2233     Users are strongly encouraged not to use `pred' any longer,
  2234     because it will disappear altogether at some point.
  2235   - Users are strongly encouraged to write "0 < n" rather than
  2236     "n ~= 0". Theorems and proof tools have been modified towards this
  2237     `standard'.
  2238 
  2239 * HOL/Lists:
  2240   the function "set_of_list" has been renamed "set" (and its theorems too);
  2241   the function "nth" now takes its arguments in the reverse order and
  2242   has acquired the infix notation "!" as in "xs!n".
  2243 
  2244 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2245 
  2246 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2247   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2248 
  2249 * HOL/record: extensible records with schematic structural subtyping
  2250 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2251 still lacks various theorems and concrete record syntax;
  2252 
  2253 
  2254 *** HOLCF ***
  2255 
  2256 * removed "axioms" and "generated by" sections;
  2257 
  2258 * replaced "ops" section by extended "consts" section, which is capable of
  2259   handling the continuous function space "->" directly;
  2260 
  2261 * domain package:
  2262   . proves theorems immediately and stores them in the theory,
  2263   . creates hierachical name space,
  2264   . now uses normal mixfix annotations (instead of cinfix...),
  2265   . minor changes to some names and values (for consistency),
  2266   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2267   . separator between mutual domain defs: changed "," to "and",
  2268   . improved handling of sort constraints;  now they have to
  2269     appear on the left-hand side of the equations only;
  2270 
  2271 * fixed LAM <x,y,zs>.b syntax;
  2272 
  2273 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2274 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2275 
  2276 
  2277 *** FOL and ZF ***
  2278 
  2279 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2280   with `addloop' of the simplifier to faciliate case splitting in premises.
  2281 
  2282 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2283 in HOL, they strip ALL and --> from proved theorems;
  2284 
  2285 
  2286 
  2287 New in Isabelle94-8 (May 1997)
  2288 ------------------------------
  2289 
  2290 *** General Changes ***
  2291 
  2292 * new utilities to build / run / maintain Isabelle etc. (in parts
  2293 still somewhat experimental); old Makefiles etc. still functional;
  2294 
  2295 * new 'Isabelle System Manual';
  2296 
  2297 * INSTALL text, together with ./configure and ./build scripts;
  2298 
  2299 * reimplemented type inference for greater efficiency, better error
  2300 messages and clean internal interface;
  2301 
  2302 * prlim command for dealing with lots of subgoals (an easier way of
  2303 setting goals_limit);
  2304 
  2305 
  2306 *** Syntax ***
  2307 
  2308 * supports alternative (named) syntax tables (parser and pretty
  2309 printer); internal interface is provided by add_modesyntax(_i);
  2310 
  2311 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2312 be used in conjunction with the Isabelle symbol font; uses the
  2313 "symbols" syntax table;
  2314 
  2315 * added token_translation interface (may translate name tokens in
  2316 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2317 the current print_mode); IMPORTANT: user print translation functions
  2318 are responsible for marking newly introduced bounds
  2319 (Syntax.mark_boundT);
  2320 
  2321 * token translations for modes "xterm" and "xterm_color" that display
  2322 names in bold, underline etc. or colors (which requires a color
  2323 version of xterm);
  2324 
  2325 * infixes may now be declared with names independent of their syntax;
  2326 
  2327 * added typed_print_translation (like print_translation, but may
  2328 access type of constant);
  2329 
  2330 
  2331 *** Classical Reasoner ***
  2332 
  2333 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2334 some limitations.  Blast_tac...
  2335   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2336   + ignores elimination rules that don't have the correct format
  2337         (the conclusion MUST be a formula variable)
  2338   + ignores types, which can make HOL proofs fail
  2339   + rules must not require higher-order unification, e.g. apply_type in ZF
  2340     [message "Function Var's argument not a bound variable" relates to this]
  2341   + its proof strategy is more general but can actually be slower
  2342 
  2343 * substitution with equality assumptions no longer permutes other
  2344 assumptions;
  2345 
  2346 * minor changes in semantics of addafter (now called addaltern); renamed
  2347 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2348 (and access functions for it);
  2349 
  2350 * improved combination of classical reasoner and simplifier:
  2351   + functions for handling clasimpsets
  2352   + improvement of addss: now the simplifier is called _after_ the
  2353     safe steps.
  2354   + safe variant of addss called addSss: uses safe simplifications
  2355     _during_ the safe steps. It is more complete as it allows multiple
  2356     instantiations of unknowns (e.g. with slow_tac).
  2357 
  2358 *** Simplifier ***
  2359 
  2360 * added interface for simplification procedures (functions that
  2361 produce *proven* rewrite rules on the fly, depending on current
  2362 redex);
  2363 
  2364 * ordering on terms as parameter (used for ordered rewriting);
  2365 
  2366 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2367 
  2368 * the solver is now split into a safe and an unsafe part.
  2369 This should be invisible for the normal user, except that the
  2370 functions setsolver and addsolver have been renamed to setSolver and
  2371 addSolver; added safe_asm_full_simp_tac;
  2372 
  2373 
  2374 *** HOL ***
  2375 
  2376 * a generic induction tactic `induct_tac' which works for all datatypes and
  2377 also for type `nat';
  2378 
  2379 * a generic case distinction tactic `exhaust_tac' which works for all
  2380 datatypes and also for type `nat';
  2381 
  2382 * each datatype comes with a function `size';
  2383 
  2384 * patterns in case expressions allow tuple patterns as arguments to
  2385 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2386 
  2387 * primrec now also works with type nat;
  2388 
  2389 * recdef: a new declaration form, allows general recursive functions to be
  2390 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2391 
  2392 * the constant for negation has been renamed from "not" to "Not" to
  2393 harmonize with FOL, ZF, LK, etc.;
  2394 
  2395 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2396 infinite lists;
  2397 
  2398 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2399 
  2400 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2401 problems in commutative rings, using axiomatic type classes for + and *;
  2402 
  2403 * more examples in HOL/MiniML and HOL/Auth;
  2404 
  2405 * more default rewrite rules for quantifiers, union/intersection;
  2406 
  2407 * a new constant `arbitrary == @x.False';
  2408 
  2409 * HOLCF/IOA replaces old HOL/IOA;
  2410 
  2411 * HOLCF changes: derived all rules and arities
  2412   + axiomatic type classes instead of classes
  2413   + typedef instead of faking type definitions
  2414   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2415   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2416   + eliminated the types void, one, tr
  2417   + use unit lift and bool lift (with translations) instead of one and tr
  2418   + eliminated blift from Lift3.thy (use Def instead of blift)
  2419   all eliminated rules are derived as theorems --> no visible changes ;
  2420 
  2421 
  2422 *** ZF ***
  2423 
  2424 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2425 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2426 as ZF_cs addSIs [equalityI];
  2427 
  2428 
  2429 
  2430 New in Isabelle94-7 (November 96)
  2431 ---------------------------------
  2432 
  2433 * allowing negative levels (as offsets) in prlev and choplev;
  2434 
  2435 * super-linear speedup for large simplifications;
  2436 
  2437 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2438 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2439 FAIL); can suppress it using the command Delsimps (ex_simps @
  2440 all_simps); De Morgan laws are also now included, by default;
  2441 
  2442 * improved printing of ==>  :  ~:
  2443 
  2444 * new object-logic "Sequents" adds linear logic, while replacing LK
  2445 and Modal (thanks to Sara Kalvala);
  2446 
  2447 * HOL/Auth: correctness proofs for authentication protocols;
  2448 
  2449 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2450 examples on HOL/Auth);
  2451 
  2452 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2453 the rewriter and classical reasoner simultaneously;
  2454 
  2455 * function uresult no longer returns theorems in "standard" format;
  2456 regain previous version by: val uresult = standard o uresult;
  2457 
  2458 
  2459 
  2460 New in Isabelle94-6
  2461 -------------------
  2462 
  2463 * oracles -- these establish an interface between Isabelle and trusted
  2464 external reasoners, which may deliver results as theorems;
  2465 
  2466 * proof objects (in particular record all uses of oracles);
  2467 
  2468 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2469 
  2470 * "constdefs" section in theory files;
  2471 
  2472 * "primrec" section (HOL) no longer requires names;
  2473 
  2474 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2475 
  2476 
  2477 
  2478 New in Isabelle94-5
  2479 -------------------
  2480 
  2481 * reduced space requirements;
  2482 
  2483 * automatic HTML generation from theories;
  2484 
  2485 * theory files no longer require "..." (quotes) around most types;
  2486 
  2487 * new examples, including two proofs of the Church-Rosser theorem;
  2488 
  2489 * non-curried (1994) version of HOL is no longer distributed;
  2490 
  2491 
  2492 
  2493 New in Isabelle94-4
  2494 -------------------
  2495 
  2496 * greatly reduced space requirements;
  2497 
  2498 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2499 
  2500 * searchable theorem database (see the section "Retrieving theorems" on
  2501 page 8 of the Reference Manual);
  2502 
  2503 * new examples, including Grabczewski's monumental case study of the
  2504 Axiom of Choice;
  2505 
  2506 * The previous version of HOL renamed to Old_HOL;
  2507 
  2508 * The new version of HOL (previously called CHOL) uses a curried syntax
  2509 for functions.  Application looks like f a b instead of f(a,b);
  2510 
  2511 * Mutually recursive inductive definitions finally work in HOL;
  2512 
  2513 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2514 translates to the operator "split";
  2515 
  2516 
  2517 
  2518 New in Isabelle94-3
  2519 -------------------
  2520 
  2521 * new infix operator, addss, allowing the classical reasoner to
  2522 perform simplification at each step of its search.  Example:
  2523         fast_tac (cs addss ss)
  2524 
  2525 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2526 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2527 look like (a,b) instead of <a,b>;
  2528 
  2529 * PLEASE NOTE: CHOL will eventually replace HOL!
  2530 
  2531 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2532 It translates to the operator "split".  A new theory of integers is available;
  2533 
  2534 * In ZF, integer numerals now denote two's-complement binary integers.
  2535 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2536 
  2537 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2538 of the Axiom of Choice;
  2539 
  2540 
  2541 
  2542 New in Isabelle94-2
  2543 -------------------
  2544 
  2545 * Significantly faster resolution;
  2546 
  2547 * the different sections in a .thy file can now be mixed and repeated
  2548 freely;
  2549 
  2550 * Database of theorems for FOL, HOL and ZF.  New
  2551 commands including qed, qed_goal and bind_thm store theorems in the database.
  2552 
  2553 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2554 a given theory (thms_of), or find out what theory a theorem was proved in
  2555 (theory_of_thm);
  2556 
  2557 * Bugs fixed in the inductive definition and datatype packages;
  2558 
  2559 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2560 and HOL_dup_cs obsolete;
  2561 
  2562 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2563 have been removed;
  2564 
  2565 * Simpler definition of function space in ZF;
  2566 
  2567 * new results about cardinal and ordinal arithmetic in ZF;
  2568 
  2569 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2570 types;
  2571 
  2572 
  2573 $Id$