NEWS
author ballarin
Fri Nov 14 14:35:55 2003 +0100 (2003-11-14)
changeset 14257 a7ef3f7588c5
parent 14255 e6e3e3f0deed
child 14283 516358ca7b42
permissions -rw-r--r--
Type inference bug in Isar attributes "where" and "of" fixed.
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** General ***
     8 
     9 * Pure: Greek letters (except small lambda, \<lambda>), as well as gothic
    10   (\<aa>...\<zz>\<AA>...\<ZZ>), caligraphic (\<A>...\<Z>), and euler
    11   (\<a>...\<z>), are now considered normal letters, and can therefore
    12   be used anywhere where an ASCII letter (a...zA...Z) has until
    13   now. COMPATIBILITY: This obviously changes the parsing of some
    14   terms, especially where a symbol has been used as a binder, say
    15   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed
    16   as an identifier.  Fix it by inserting a space around former
    17   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in
    18   existing theory and ML files.
    19 
    20 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.
    21 
    22 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now 
    23   allowed in identifiers. Similar to greek letters \<^isub> is now considered 
    24   a normal (but invisible) letter. For multiple letter subscripts repeat 
    25   \<^isub> like this: x\<^isub>1\<^isub>2. 
    26 
    27 * Pure: Using new Isar command "finalconsts" (or the ML functions
    28   Theory.add_finals or Theory.add_finals_i) it is now possible to
    29   declare constants "final", which prevents their being given a definition
    30   later.  It is useful for constants whose behaviour is fixed axiomatically
    31   rather than definitionally, such as the meta-logic connectives.
    32 
    33 *** Isar ***
    34 
    35 * Tactic emulation methods ?rule_tac, cut_tac, subgoal_tac and thin_tac:
    36   - Now understand static (Isar) contexts.  As a consequence, users of Isar
    37     locales are no longer forced to write Isar proof scripts.
    38     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
    39     emulations.
    40   - INCOMPATIBILITY: names of variables to be instantiated may no
    41     longer be enclosed in quotes.  Instead, precede variable name with `?'.
    42     This is consistent with the instantiation attribute "where".
    43 
    44 * Attributes "where" and "of":
    45   Now take type variables of instantiated theorem into account when reading
    46   the instantiation string.  This fixes a bug that caused instantiated
    47   theorems to have too special types in some circumstances.
    48 
    49 * Locales:
    50   - Goal statements involving the context element "includes" no longer
    51     generate theorems with internal delta predicates (those ending on
    52     "_axioms") in the premise.
    53     Resolve particular premise with <locale>.intro to obtain old form.
    54   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
    55     specification and "includes" elements in goal statement.
    56   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
    57     [intro?] and [elim?] (respectively) by default.
    58 
    59 * HOL: Tactic emulation methods induct_tac and case_tac understand static
    60   (Isar) contexts.
    61 
    62 *** HOL ***
    63 
    64 * Records:
    65   - Record types are now by default printed with their type abbreviation
    66     instead of the list of all field types. This can be configured via
    67     the reference "print_record_type_abbr".
    68   - Simproc "record_upd_simproc" for simplification of multiple updates added 
    69     (not enabled by default).
    70   - Tactic "record_split_simp_tac" to split and simplify records added.
    71  
    72 * 'specification' command added, allowing for definition by
    73   specification.  There is also an 'ax_specification' command that
    74   introduces the new constants axiomatically.
    75 
    76 * SET-Protocol: formalization and verification of the SET protocol suite;
    77 
    78 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
    79  defintions, thanks to Sava Krsti\'{c} and John Matthews.
    80 
    81 New in Isabelle2003 (May 2003)
    82 --------------------------------
    83 
    84 *** General ***
    85 
    86 * Provers/simplifier:
    87 
    88   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
    89     Assumptions are now subject to complete mutual simplification,
    90     not just from left to right. The simplifier now preserves
    91     the order of assumptions.
    92 
    93     Potential INCOMPATIBILITY:
    94 
    95     -- simp sometimes diverges where the old version did
    96        not, e.g. invoking simp on the goal
    97 
    98         [| P (f x); y = x; f x = f y |] ==> Q
    99 
   100        now gives rise to the infinite reduction sequence
   101 
   102         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   103 
   104        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   105        kind of problem.
   106 
   107     -- Tactics combining classical reasoner and simplification (such as auto)
   108        are also affected by this change, because many of them rely on
   109        simp. They may sometimes diverge as well or yield a different numbers
   110        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   111        in case of problems. Sometimes subsequent calls to the classical
   112        reasoner will fail because a preceeding call to the simplifier too
   113        eagerly simplified the goal, e.g. deleted redundant premises.
   114 
   115   - The simplifier trace now shows the names of the applied rewrite rules
   116 
   117   - You can limit the number of recursive invocations of the simplifier
   118     during conditional rewriting (where the simplifie tries to solve the
   119     conditions before applying the rewrite rule):
   120     ML "simp_depth_limit := n"
   121     where n is an integer. Thus you can force termination where previously
   122     the simplifier would diverge.
   123 
   124   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   125 
   126   - No longer aborts on failed congruence proof.  Instead, the
   127     congruence is ignored.
   128 
   129 * Pure: New generic framework for extracting programs from constructive
   130   proofs. See HOL/Extraction.thy for an example instantiation, as well
   131   as HOL/Extraction for some case studies.
   132 
   133 * Pure: The main goal of the proof state is no longer shown by default, only
   134 the subgoals. This behaviour is controlled by a new flag.
   135    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   136 (ML: Proof.show_main_goal).
   137 
   138 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   139 rules whose conclusion matches subgoal 1:
   140       PG menu: Isabelle/Isar -> Show me -> matching rules
   141 The rules are ordered by how closely they match the subgoal.
   142 In particular, rules that solve a subgoal outright are displayed first
   143 (or rather last, the way they are printed).
   144 (ML: ProofGeneral.print_intros())
   145 
   146 * Pure: New flag trace_unify_fail causes unification to print
   147 diagnostic information (PG: in trace buffer) when it fails. This is
   148 useful for figuring out why single step proofs like rule, erule or
   149 assumption failed.
   150 
   151 * Pure: Locale specifications now produce predicate definitions
   152 according to the body of text (covering assumptions modulo local
   153 definitions); predicate "loc_axioms" covers newly introduced text,
   154 while "loc" is cumulative wrt. all included locale expressions; the
   155 latter view is presented only on export into the global theory
   156 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   157 on the old view without predicates;
   158 
   159 * Pure: predefined locales "var" and "struct" are useful for sharing
   160 parameters (as in CASL, for example); just specify something like
   161 ``var x + var y + struct M'' as import;
   162 
   163 * Pure: improved thms_containing: proper indexing of facts instead of
   164 raw theorems; check validity of results wrt. current name space;
   165 include local facts of proof configuration (also covers active
   166 locales), cover fixed variables in index; may use "_" in term
   167 specification; an optional limit for the number of printed facts may
   168 be given (the default is 40);
   169 
   170 * Pure: disallow duplicate fact bindings within new-style theory files
   171 (batch-mode only);
   172 
   173 * Provers: improved induct method: assumptions introduced by case
   174 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   175 the goal statement); "foo" still refers to all facts collectively;
   176 
   177 * Provers: the function blast.overloaded has been removed: all constants
   178 are regarded as potentially overloaded, which improves robustness in exchange
   179 for slight decrease in efficiency;
   180 
   181 * Provers/linorder: New generic prover for transitivity reasoning over
   182 linear orders.  Note: this prover is not efficient!
   183 
   184 * Isar: preview of problems to finish 'show' now produce an error
   185 rather than just a warning (in interactive mode);
   186 
   187 
   188 *** HOL ***
   189 
   190 * arith(_tac)
   191 
   192  - Produces a counter example if it cannot prove a goal.
   193    Note that the counter example may be spurious if the goal is not a formula
   194    of quantifier-free linear arithmetic.
   195    In ProofGeneral the counter example appears in the trace buffer.
   196 
   197  - Knows about div k and mod k where k is a numeral of type nat or int.
   198 
   199  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   200    linear arithmetic fails. This takes account of quantifiers and divisibility.
   201    Presburger arithmetic can also be called explicitly via presburger(_tac). 
   202 
   203 * simp's arithmetic capabilities have been enhanced a bit: it now
   204 takes ~= in premises into account (by performing a case split);
   205 
   206 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   207 are distributed over a sum of terms;
   208 
   209 * New tactic "trans_tac" and method "trans" instantiate
   210 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   211 "<=", "<" and "="). 
   212 
   213 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main 
   214 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   215 
   216 * 'typedef' command has new option "open" to suppress the set
   217 definition;
   218 
   219 * functions Min and Max on finite sets have been introduced (theory
   220 Finite_Set);
   221 
   222 * attribute [symmetric] now works for relations as well; it turns
   223 (x,y) : R^-1 into (y,x) : R, and vice versa;
   224 
   225 * induct over a !!-quantified statement (say !!x1..xn):
   226   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   227 
   228 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   229 %x. None. Warning: empty_def now refers to the previously hidden definition
   230 of the empty set.
   231 
   232 * Algebra: formalization of classical algebra.  Intended as base for
   233 any algebraic development in Isabelle.  Currently covers group theory
   234 (up to Sylow's theorem) and ring theory (Universal Property of
   235 Univariate Polynomials).  Contributions welcome;
   236 
   237 * GroupTheory: deleted, since its material has been moved to Algebra;
   238 
   239 * Complex: new directory of the complex numbers with numeric constants, 
   240 nonstandard complex numbers, and some complex analysis, standard and 
   241 nonstandard (Jacques Fleuriot);
   242 
   243 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   244 
   245 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques 
   246 Fleuriot);
   247 
   248 * Real/HahnBanach: updated and adapted to locales;
   249 
   250 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   251 Gray and Kramer);
   252 
   253 * UNITY: added the Meier-Sanders theory of progress sets;
   254 
   255 * MicroJava: bytecode verifier and lightweight bytecode verifier
   256 as abstract algorithms, instantiated to the JVM;
   257 
   258 * Bali: Java source language formalization. Type system, operational
   259 semantics, axiomatic semantics. Supported language features:
   260 classes, interfaces, objects,virtual methods, static methods,
   261 static/instance fields, arrays, access modifiers, definite
   262 assignment, exceptions.
   263 
   264 
   265 *** ZF ***
   266 
   267 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   268 universe, etc.);
   269 
   270 * Main ZF: virtually all theories converted to new-style format;
   271 
   272 
   273 *** ML ***
   274 
   275 * Pure: Tactic.prove provides sane interface for internal proofs;
   276 omits the infamous "standard" operation, so this is more appropriate
   277 than prove_goalw_cterm in many situations (e.g. in simprocs);
   278 
   279 * Pure: improved error reporting of simprocs;
   280 
   281 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   282 up simprocs;
   283 
   284 
   285 *** Document preparation ***
   286 
   287 * uses \par instead of \\ for line breaks in theory text. This may
   288 shift some page breaks in large documents. To get the old behaviour
   289 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   290 
   291 * minimized dependencies of isabelle.sty and isabellesym.sty on 
   292 other packages
   293 
   294 * \<euro> now needs package babel/greek instead of marvosym (which
   295 broke \Rightarrow)
   296 
   297 * normal size for \<zero>...\<nine> (uses \mathbf instead of 
   298 textcomp package)
   299 
   300 
   301 New in Isabelle2002 (March 2002)
   302 --------------------------------
   303 
   304 *** Document preparation ***
   305 
   306 * greatly simplified document preparation setup, including more
   307 graceful interpretation of isatool usedir -i/-d/-D options, and more
   308 instructive isatool mkdir; users should basically be able to get
   309 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   310 users may run a separate document processing stage manually like this:
   311 "isatool usedir -D output HOL Test && isatool document Test/output";
   312 
   313 * theory dependency graph may now be incorporated into documents;
   314 isatool usedir -g true will produce session_graph.eps/.pdf for use
   315 with \includegraphics of LaTeX;
   316 
   317 * proper spacing of consecutive markup elements, especially text
   318 blocks after section headings;
   319 
   320 * support bold style (for single symbols only), input syntax is like
   321 this: "\<^bold>\<alpha>" or "\<^bold>A";
   322 
   323 * \<bullet> is now output as bold \cdot by default, which looks much
   324 better in printed text;
   325 
   326 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   327 note that these symbols are currently unavailable in Proof General /
   328 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   329 
   330 * isatool latex no longer depends on changed TEXINPUTS, instead
   331 isatool document copies the Isabelle style files to the target
   332 location;
   333 
   334 
   335 *** Isar ***
   336 
   337 * Pure/Provers: improved proof by cases and induction;
   338   - 'case' command admits impromptu naming of parameters (such as
   339     "case (Suc n)");
   340   - 'induct' method divinates rule instantiation from the inductive
   341     claim; no longer requires excessive ?P bindings for proper
   342     instantiation of cases;
   343   - 'induct' method properly enumerates all possibilities of set/type
   344     rules; as a consequence facts may be also passed through *type*
   345     rules without further ado;
   346   - 'induct' method now derives symbolic cases from the *rulified*
   347     rule (before it used to rulify cases stemming from the internal
   348     atomized version); this means that the context of a non-atomic
   349     statement becomes is included in the hypothesis, avoiding the
   350     slightly cumbersome show "PROP ?case" form;
   351   - 'induct' may now use elim-style induction rules without chaining
   352     facts, using ``missing'' premises from the goal state; this allows
   353     rules stemming from inductive sets to be applied in unstructured
   354     scripts, while still benefitting from proper handling of non-atomic
   355     statements; NB: major inductive premises need to be put first, all
   356     the rest of the goal is passed through the induction;
   357   - 'induct' proper support for mutual induction involving non-atomic
   358     rule statements (uses the new concept of simultaneous goals, see
   359     below);
   360   - append all possible rule selections, but only use the first
   361     success (no backtracking);
   362   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   363   - undeclared rule case names default to numbers 1, 2, 3, ...;
   364   - added 'print_induct_rules' (covered by help item in recent Proof
   365     General versions);
   366   - moved induct/cases attributes to Pure, methods to Provers;
   367   - generic method setup instantiated for FOL and HOL;
   368 
   369 * Pure: support multiple simultaneous goal statements, for example
   370 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   371 meta-level mechanism, this acts as if several individual goals had
   372 been stated separately; in particular common proof methods need to be
   373 repeated in order to cover all claims; note that a single elimination
   374 step is *not* sufficient to establish the two conjunctions, so this
   375 fails:
   376 
   377   assume "A & B" then have A and B ..   (*".." fails*)
   378 
   379 better use "obtain" in situations as above; alternative refer to
   380 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   381 
   382 * Pure: proper integration with ``locales''; unlike the original
   383 version by Florian Kammüller, Isar locales package high-level proof
   384 contexts rather than raw logical ones (e.g. we admit to include
   385 attributes everywhere); operations on locales include merge and
   386 rename; support for implicit arguments (``structures''); simultaneous
   387 type-inference over imports and text; see also HOL/ex/Locales.thy for
   388 some examples;
   389 
   390 * Pure: the following commands have been ``localized'', supporting a
   391 target locale specification "(in name)": 'lemma', 'theorem',
   392 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   393 stored both within the locale and at the theory level (exported and
   394 qualified by the locale name);
   395 
   396 * Pure: theory goals may now be specified in ``long'' form, with
   397 ad-hoc contexts consisting of arbitrary locale elements. for example
   398 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   399 definitions may be given, too); the result is a meta-level rule with
   400 the context elements being discharged in the obvious way;
   401 
   402 * Pure: new proof command 'using' allows to augment currently used
   403 facts after a goal statement ('using' is syntactically analogous to
   404 'apply', but acts on the goal's facts only); this allows chained facts
   405 to be separated into parts given before and after a claim, as in
   406 ``from a and b have C using d and e <proof>'';
   407 
   408 * Pure: renamed "antecedent" case to "rule_context";
   409 
   410 * Pure: new 'judgment' command records explicit information about the
   411 object-logic embedding (used by several tools internally); no longer
   412 use hard-wired "Trueprop";
   413 
   414 * Pure: added 'corollary' command;
   415 
   416 * Pure: fixed 'token_translation' command;
   417 
   418 * Pure: removed obsolete 'exported' attribute;
   419 
   420 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   421 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   422 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   423 
   424 * Pure: method 'atomize' presents local goal premises as object-level
   425 statements (atomic meta-level propositions); setup controlled via
   426 rewrite rules declarations of 'atomize' attribute; example
   427 application: 'induct' method with proper rule statements in improper
   428 proof *scripts*;
   429 
   430 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   431 now consider the syntactic context of assumptions, giving a better
   432 chance to get type-inference of the arguments right (this is
   433 especially important for locales);
   434 
   435 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   436 mode;
   437 
   438 * Pure/obtain: the formal conclusion "thesis", being marked as
   439 ``internal'', may no longer be reference directly in the text;
   440 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   441 situations;
   442 
   443 * Pure: generic 'sym' attribute which declares a rule both as pure
   444 'elim?' and for the 'symmetric' operation;
   445 
   446 * Pure: marginal comments ``--'' may now occur just anywhere in the
   447 text; the fixed correlation with particular command syntax has been
   448 discontinued;
   449 
   450 * Pure: new method 'rules' is particularly well-suited for proof
   451 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   452 but often produces more compact proof terms with less detours;
   453 
   454 * Pure/Provers/classical: simplified integration with pure rule
   455 attributes and methods; the classical "intro?/elim?/dest?"
   456 declarations coincide with the pure ones; the "rule" method no longer
   457 includes classically swapped intros; "intro" and "elim" methods no
   458 longer pick rules from the context; also got rid of ML declarations
   459 AddXIs/AddXEs/AddXDs; all of this has some potential for
   460 INCOMPATIBILITY;
   461 
   462 * Provers/classical: attribute 'swapped' produces classical inversions
   463 of introduction rules;
   464 
   465 * Provers/simplifier: 'simplified' attribute may refer to explicit
   466 rules instead of full simplifier context; 'iff' attribute handles
   467 conditional rules;
   468 
   469 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   470 
   471 * HOL: 'recdef' now fails on unfinished automated proofs, use
   472 "(permissive)" option to recover old behavior;
   473 
   474 * HOL: 'inductive' no longer features separate (collective) attributes
   475 for 'intros' (was found too confusing);
   476 
   477 * HOL: properly declared induction rules less_induct and
   478 wf_induct_rule;
   479 
   480 
   481 *** HOL ***
   482 
   483 * HOL: moved over to sane numeral syntax; the new policy is as
   484 follows:
   485 
   486   - 0 and 1 are polymorphic constants, which are defined on any
   487   numeric type (nat, int, real etc.);
   488 
   489   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   490   binary representation internally;
   491 
   492   - type nat has special constructor Suc, and generally prefers Suc 0
   493   over 1::nat and Suc (Suc 0) over 2::nat;
   494 
   495 This change may cause significant problems of INCOMPATIBILITY; here
   496 are some hints on converting existing sources:
   497 
   498   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   499   entities, so expressions involving "-" (unary or binary minus) need
   500   to be spaced properly;
   501 
   502   - existing occurrences of "1" may need to be constraint "1::nat" or
   503   even replaced by Suc 0; similar for old "2";
   504 
   505   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   506 
   507   - remove all special provisions on numerals in proofs;
   508 
   509 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   510 representation (depends on bin_arith_simps in the default context);
   511 
   512 * HOL: symbolic syntax for x^2 (numeral 2);
   513 
   514 * HOL: the class of all HOL types is now called "type" rather than
   515 "term"; INCOMPATIBILITY, need to adapt references to this type class
   516 in axclass/classes, instance/arities, and (usually rare) occurrences
   517 in typings (of consts etc.); internally the class is called
   518 "HOL.type", ML programs should refer to HOLogic.typeS;
   519 
   520 * HOL/record package improvements:
   521   - new derived operations "fields" to build a partial record section,
   522     "extend" to promote a fixed record to a record scheme, and
   523     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   524     declared as simp by default;
   525   - shared operations ("more", "fields", etc.) now need to be always
   526     qualified) --- potential INCOMPATIBILITY;
   527   - removed "make_scheme" operations (use "make" with "extend") --
   528     INCOMPATIBILITY;
   529   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   530   - provides cases/induct rules for use with corresponding Isar
   531     methods (for concrete records, record schemes, concrete more
   532     parts, and schematic more parts -- in that order);
   533   - internal definitions directly based on a light-weight abstract
   534     theory of product types over typedef rather than datatype;
   535 
   536 * HOL: generic code generator for generating executable ML code from
   537 specifications; specific support for HOL constructs such as inductive
   538 datatypes and sets, as well as recursive functions; can be invoked
   539 via 'generate_code' theory section;
   540 
   541 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   542 
   543 * HOL: consolidated and renamed several theories.  In particular:
   544 	Ord.thy has been absorbed into HOL.thy
   545 	String.thy has been absorbed into List.thy
   546  
   547 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   548 (beware of argument permutation!);
   549 
   550 * HOL: linorder_less_split superseded by linorder_cases;
   551 
   552 * HOL/List: "nodups" renamed to "distinct";
   553 
   554 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   555 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   556   - Ex_def has changed, now need to use some_eq_ex
   557 
   558 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   559 in this (rare) case use:
   560 
   561   delSWrapper "split_all_tac"
   562   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   563 
   564 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   565 MAY FAIL;
   566 
   567 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   568 Isabelle's type classes, ^ on functions and relations has too general
   569 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   570 necessary to attach explicit type constraints;
   571 
   572 * HOL/Relation: the prefix name of the infix "O" has been changed from
   573 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   574 renamed accordingly (eg "compI" -> "rel_compI").
   575 
   576 * HOL: syntax translations now work properly with numerals and records
   577 expressions;
   578 
   579 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   580 of "lam" -- INCOMPATIBILITY;
   581 
   582 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   583 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   584 renamed "Product_Type.unit";
   585 
   586 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   587 
   588 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   589 the "cases" method);
   590 
   591 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   592 Florian Kammüller);
   593 
   594 * HOL/IMP: updated and converted to new-style theory format; several
   595 parts turned into readable document, with proper Isar proof texts and
   596 some explanations (by Gerwin Klein);
   597 
   598 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   599 
   600 * HOL-Hyperreal is now a logic image;
   601 
   602 
   603 *** HOLCF ***
   604 
   605 * Isar: consts/constdefs supports mixfix syntax for continuous
   606 operations;
   607 
   608 * Isar: domain package adapted to new-style theory format, e.g. see
   609 HOLCF/ex/Dnat.thy;
   610 
   611 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   612 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   613 lift.induct_tac, always use UU instead of Undef;
   614 
   615 * HOLCF/IMP: updated and converted to new-style theory;
   616 
   617 
   618 *** ZF ***
   619 
   620 * Isar: proper integration of logic-specific tools and packages,
   621 including theory commands '(co)inductive', '(co)datatype',
   622 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   623 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   624 
   625 * theory Main no longer includes AC; for the Axiom of Choice, base
   626 your theory on Main_ZFC;
   627 
   628 * the integer library now covers quotients and remainders, with many
   629 laws relating division to addition, multiplication, etc.;
   630 
   631 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   632 typeless version of the formalism;
   633 
   634 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   635 format;
   636 
   637 * ZF/Induct: new directory for examples of inductive definitions,
   638 including theory Multiset for multiset orderings; converted to
   639 new-style theory format;
   640 
   641 * ZF: many new theorems about lists, ordinals, etc.;
   642 
   643 
   644 *** General ***
   645 
   646 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   647 variable proof controls level of detail: 0 = no proofs (only oracle
   648 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   649 also ref manual for further ML interfaces;
   650 
   651 * Pure/axclass: removed obsolete ML interface
   652 goal_subclass/goal_arity;
   653 
   654 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   655 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   656 separate tokens, so expressions involving minus need to be spaced
   657 properly;
   658 
   659 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   660 rather than "infixl" or "infixr";
   661 
   662 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   663 sort constraint specifications in type inference; e.g. "x::_::foo"
   664 ensures that the type of "x" is of sort "foo" (but not necessarily a
   665 type variable);
   666 
   667 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   668 control output of nested => (types); the default behavior is
   669 "type_brackets";
   670 
   671 * Pure/syntax: builtin parse translation for "_constify" turns valued
   672 tokens into AST constants;
   673 
   674 * Pure/syntax: prefer later declarations of translations and print
   675 translation functions; potential INCOMPATIBILITY: need to reverse
   676 multiple declarations for same syntax element constant;
   677 
   678 * Pure/show_hyps reset by default (in accordance to existing Isar
   679 practice);
   680 
   681 * Provers/classical: renamed addaltern to addafter, addSaltern to
   682 addSafter;
   683 
   684 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   685 as well;
   686 
   687 * system: tested support for MacOS X; should be able to get Isabelle +
   688 Proof General to work in a plain Terminal after installing Poly/ML
   689 (e.g. from the Isabelle distribution area) and GNU bash alone
   690 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   691 support requires further installations, e.g. from
   692 http://fink.sourceforge.net/);
   693 
   694 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   695 
   696 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   697 of 40 MB), cf. ML_OPTIONS;
   698 
   699 * system: Proof General keywords specification is now part of the
   700 Isabelle distribution (see etc/isar-keywords.el);
   701 
   702 * system: support for persistent Proof General sessions (refrain from
   703 outdating all loaded theories on startup); user may create writable
   704 logic images like this: ``isabelle -q HOL Test'';
   705 
   706 * system: smart selection of Isabelle process versus Isabelle
   707 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   708 run both "isabelle" and "Isabelle" even if file names are badly
   709 damaged (executable inspects the case of the first letter of its own
   710 name); added separate "isabelle-process" and "isabelle-interface";
   711 
   712 * system: refrain from any attempt at filtering input streams; no
   713 longer support ``8bit'' encoding of old isabelle font, instead proper
   714 iso-latin characters may now be used; the related isatools
   715 "symbolinput" and "nonascii" have disappeared as well;
   716 
   717 * system: removed old "xterm" interface (the print modes "xterm" and
   718 "xterm_color" are still available for direct use in a suitable
   719 terminal);
   720 
   721 
   722 
   723 New in Isabelle99-2 (February 2001)
   724 -----------------------------------
   725 
   726 *** Overview of INCOMPATIBILITIES ***
   727 
   728 * HOL: please note that theories in the Library and elsewhere often use the
   729 new-style (Isar) format; to refer to their theorems in an ML script you must
   730 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   731 
   732 * HOL: inductive package no longer splits induction rule aggressively,
   733 but only as far as specified by the introductions given; the old
   734 format may be recovered via ML function complete_split_rule or attribute
   735 'split_rule (complete)';
   736 
   737 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   738 gfp_Tarski to gfp_unfold;
   739 
   740 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   741 
   742 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   743 relation); infix "^^" has been renamed "``"; infix "``" has been
   744 renamed "`"; "univalent" has been renamed "single_valued";
   745 
   746 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   747 operation;
   748 
   749 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   750 
   751 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   752 
   753 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   754 consequence, it is no longer monotonic wrt. the local goal context
   755 (which is now passed through the inductive cases);
   756 
   757 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   758 \<gg> to \<ggreater>;
   759 
   760 
   761 *** Document preparation ***
   762 
   763 * \isabellestyle{NAME} selects version of Isabelle output (currently
   764 available: are "it" for near math-mode best-style output, "sl" for
   765 slanted text style, and "tt" for plain type-writer; if no
   766 \isabellestyle command is given, output is according to slanted
   767 type-writer);
   768 
   769 * support sub/super scripts (for single symbols only), input syntax is
   770 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   771 
   772 * some more standard symbols; see Appendix A of the system manual for
   773 the complete list of symbols defined in isabellesym.sty;
   774 
   775 * improved isabelle style files; more abstract symbol implementation
   776 (should now use \isamath{...} and \isatext{...} in custom symbol
   777 definitions);
   778 
   779 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   780 state; Note that presentation of goal states does not conform to
   781 actual human-readable proof documents.  Please do not include goal
   782 states into document output unless you really know what you are doing!
   783 
   784 * proper indentation of antiquoted output with proportional LaTeX
   785 fonts;
   786 
   787 * no_document ML operator temporarily disables LaTeX document
   788 generation;
   789 
   790 * isatool unsymbolize tunes sources for plain ASCII communication;
   791 
   792 
   793 *** Isar ***
   794 
   795 * Pure: Isar now suffers initial goal statements to contain unbound
   796 schematic variables (this does not conform to actual readable proof
   797 documents, due to unpredictable outcome and non-compositional proof
   798 checking); users who know what they are doing may use schematic goals
   799 for Prolog-style synthesis of proven results;
   800 
   801 * Pure: assumption method (an implicit finishing) now handles actual
   802 rules as well;
   803 
   804 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   805 initial goal, declare "that" only as Pure intro (only for single
   806 steps); the "that" rule assumption may now be involved in implicit
   807 finishing, thus ".." becomes a feasible for trivial obtains;
   808 
   809 * Pure: default proof step now includes 'intro_classes'; thus trivial
   810 instance proofs may be performed by "..";
   811 
   812 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   813 statements as well;
   814 
   815 * Pure: more robust selection of calculational rules;
   816 
   817 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   818 rule (as well as the assumption rule);
   819 
   820 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   821 lemmas, using the graph browser tool;
   822 
   823 * Pure: predict failure of "show" in interactive mode;
   824 
   825 * Pure: 'thms_containing' now takes actual terms as arguments;
   826 
   827 * HOL: improved method 'induct' --- now handles non-atomic goals
   828 (potential INCOMPATIBILITY); tuned error handling;
   829 
   830 * HOL: cases and induct rules now provide explicit hints about the
   831 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   832 any remaining facts are inserted into the goal verbatim;
   833 
   834 * HOL: local contexts (aka cases) may now contain term bindings as
   835 well; the 'cases' and 'induct' methods new provide a ?case binding for
   836 the result to be shown in each case;
   837 
   838 * HOL: added 'recdef_tc' command;
   839 
   840 * isatool convert assists in eliminating legacy ML scripts;
   841 
   842 
   843 *** HOL ***
   844 
   845 * HOL/Library: a collection of generic theories to be used together
   846 with main HOL; the theory loader path already includes this directory
   847 by default; the following existing theories have been moved here:
   848 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   849 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   850 
   851 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   852 modelling and verification task performed in Isabelle/HOL +
   853 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   854 
   855 * HOL/Algebra: special summation operator SUM no longer exists, it has
   856 been replaced by setsum; infix 'assoc' now has priority 50 (like
   857 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   858 'domain', this makes the theory consistent with mathematical
   859 literature;
   860 
   861 * HOL basics: added overloaded operations "inverse" and "divide"
   862 (infix "/"), syntax for generic "abs" operation, generic summation
   863 operator \<Sum>;
   864 
   865 * HOL/typedef: simplified package, provide more useful rules (see also
   866 HOL/subset.thy);
   867 
   868 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   869 now expressed as a proper nested rule (old-style tactic scripts may
   870 require atomize_strip_tac to cope with non-atomic premises);
   871 
   872 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   873 to "split_conv" (old name still available for compatibility);
   874 
   875 * HOL: improved concrete syntax for strings (e.g. allows translation
   876 rules with string literals);
   877 
   878 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   879  and Fleuriot's mechanization of analysis, including the transcendental
   880  functions for the reals;
   881 
   882 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   883 
   884 
   885 *** CTT ***
   886 
   887 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   888 "lam" is displayed as TWO lambda-symbols
   889 
   890 * CTT: theory Main now available, containing everything (that is, Bool
   891 and Arith);
   892 
   893 
   894 *** General ***
   895 
   896 * Pure: the Simplifier has been implemented properly as a derived rule
   897 outside of the actual kernel (at last!); the overall performance
   898 penalty in practical applications is about 50%, while reliability of
   899 the Isabelle inference kernel has been greatly improved;
   900 
   901 * print modes "brackets" and "no_brackets" control output of nested =>
   902 (types) and ==> (props); the default behaviour is "brackets";
   903 
   904 * Provers: fast_tac (and friends) now handle actual object-logic rules
   905 as assumptions as well;
   906 
   907 * system: support Poly/ML 4.0;
   908 
   909 * system: isatool install handles KDE version 1 or 2;
   910 
   911 
   912 
   913 New in Isabelle99-1 (October 2000)
   914 ----------------------------------
   915 
   916 *** Overview of INCOMPATIBILITIES ***
   917 
   918 * HOL: simplification of natural numbers is much changed; to partly
   919 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   920 issue the following ML commands:
   921 
   922   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   923   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   924 
   925 * HOL: simplification no longer dives into case-expressions; this is
   926 controlled by "t.weak_case_cong" for each datatype t;
   927 
   928 * HOL: nat_less_induct renamed to less_induct;
   929 
   930 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   931 fixsome to patch .thy and .ML sources automatically;
   932 
   933   select_equality  -> some_equality
   934   select_eq_Ex     -> some_eq_ex
   935   selectI2EX       -> someI2_ex
   936   selectI2         -> someI2
   937   selectI          -> someI
   938   select1_equality -> some1_equality
   939   Eps_sym_eq       -> some_sym_eq_trivial
   940   Eps_eq           -> some_eq_trivial
   941 
   942 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   943 
   944 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   945 instead);
   946 
   947 * HOL: the recursion equations generated by 'recdef' are now called
   948 f.simps instead of f.rules;
   949 
   950 * HOL: qed_spec_mp now also handles bounded ALL as well;
   951 
   952 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   953 sometimes be needed;
   954 
   955 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   956 
   957 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   958 
   959 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   960 product is now "<*>" instead of "Times"; the lexicographic product is
   961 now "<*lex*>" instead of "**";
   962 
   963 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   964 of main HOL, but was unused); better use HOL's datatype package;
   965 
   966 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   967 the old syntax may be recovered as follows:
   968 
   969   syntax (symbols)
   970     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   971       (infixl "\\<oplus>" 100)
   972 
   973 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   974 
   975 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   976 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   977 internally;
   978 
   979 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   980 changed from A/r to A//r;
   981 
   982 * ZF: new treatment of arithmetic (nat & int) may break some old
   983 proofs;
   984 
   985 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   986 rulify -> rule_format, elimify -> elim_format, ...);
   987 
   988 * Isar/Provers: intro/elim/dest attributes changed; renamed
   989 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   990 should have to change intro!! to intro? only); replaced "delrule" by
   991 "rule del";
   992 
   993 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   994 
   995 * Provers: strengthened force_tac by using new first_best_tac;
   996 
   997 * LaTeX document preparation: several changes of isabelle.sty (see
   998 lib/texinputs);
   999 
  1000 
  1001 *** Document preparation ***
  1002 
  1003 * formal comments (text blocks etc.) in new-style theories may now
  1004 contain antiquotations of thm/prop/term/typ/text to be presented
  1005 according to latex print mode; concrete syntax is like this:
  1006 @{term[show_types] "f(x) = a + x"};
  1007 
  1008 * isatool mkdir provides easy setup of Isabelle session directories,
  1009 including proper document sources;
  1010 
  1011 * generated LaTeX sources are now deleted after successful run
  1012 (isatool document -c); may retain a copy somewhere else via -D option
  1013 of isatool usedir;
  1014 
  1015 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1016 style files, achieving self-contained LaTeX sources and simplifying
  1017 LaTeX debugging;
  1018 
  1019 * old-style theories now produce (crude) LaTeX output as well;
  1020 
  1021 * browser info session directories are now self-contained (may be put
  1022 on WWW server seperately); improved graphs of nested sessions; removed
  1023 graph for 'all sessions';
  1024 
  1025 * several improvements in isabelle style files; \isabellestyle{it}
  1026 produces fake math mode output; \isamarkupheader is now \section by
  1027 default; see lib/texinputs/isabelle.sty etc.;
  1028 
  1029 
  1030 *** Isar ***
  1031 
  1032 * Isar/Pure: local results and corresponding term bindings are now
  1033 subject to Hindley-Milner polymorphism (similar to ML); this
  1034 accommodates incremental type-inference very nicely;
  1035 
  1036 * Isar/Pure: new derived language element 'obtain' supports
  1037 generalized existence reasoning;
  1038 
  1039 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1040 support accumulation of results, without applying any rules yet;
  1041 useful to collect intermediate results without explicit name
  1042 references, and for use with transitivity rules with more than 2
  1043 premises;
  1044 
  1045 * Isar/Pure: scalable support for case-analysis type proofs: new
  1046 'case' language element refers to local contexts symbolically, as
  1047 produced by certain proof methods; internally, case names are attached
  1048 to theorems as "tags";
  1049 
  1050 * Isar/Pure: theory command 'hide' removes declarations from
  1051 class/type/const name spaces;
  1052 
  1053 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1054 indicate potential overloading;
  1055 
  1056 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1057 
  1058 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1059 "{a,b,c}" instead of {a,b,c};
  1060 
  1061 * Isar/Pure now provides its own version of intro/elim/dest
  1062 attributes; useful for building new logics, but beware of confusion
  1063 with the version in Provers/classical;
  1064 
  1065 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1066 case name 'antecedent';
  1067 
  1068 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1069 to the current context is now done automatically);
  1070 
  1071 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1072 for definining proof methods in ML;
  1073 
  1074 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1075 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1076 most cases, one should have to change intro!! to intro? only);
  1077 replaced "delrule" by "rule del";
  1078 
  1079 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1080 'symmetric' attribute (the latter supercedes [RS sym]);
  1081 
  1082 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1083 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1084 well (including splits);
  1085 
  1086 * Isar/Provers: Simplifier and Classical methods now support all kind
  1087 of modifiers used in the past, including 'cong', 'iff', etc.
  1088 
  1089 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1090 of Simplifier and Classical reasoner);
  1091 
  1092 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1093 now support named cases; major packages (inductive, datatype, primrec,
  1094 recdef) support case names and properly name parameters;
  1095 
  1096 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1097 monotonicity conditions are extracted to be proven at end of
  1098 calculations;
  1099 
  1100 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1101 method anyway;
  1102 
  1103 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1104 split_if split_if_asm; datatype package provides theorems foo.splits =
  1105 foo.split foo.split_asm for each datatype;
  1106 
  1107 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1108 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1109 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1110 use "(cases (simplified))" method in proper proof texts);
  1111 
  1112 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1113 
  1114 * Isar: names of theorems etc. may be natural numbers as well;
  1115 
  1116 * Isar: 'pr' command: optional arguments for goals_limit and
  1117 ProofContext.prems_limit; no longer prints theory contexts, but only
  1118 proof states;
  1119 
  1120 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1121 additional print modes to be specified; e.g. "pr(latex)" will print
  1122 proof state according to the Isabelle LaTeX style;
  1123 
  1124 * Isar: improved support for emulating tactic scripts, including proof
  1125 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1126 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1127 (for HOL datatypes);
  1128 
  1129 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1130 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1131 'proof method scripts' have to be in depth-first order;
  1132 
  1133 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1134 
  1135 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1136 should instead use individual commands for printing items
  1137 (print_commands, print_methods etc.);
  1138 
  1139 * Isar: added 'nothing' --- the empty list of theorems;
  1140 
  1141 
  1142 *** HOL ***
  1143 
  1144 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1145 corresponding virtual machine and a specification of its bytecode
  1146 verifier and a lightweight bytecode verifier, including proofs of
  1147 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1148 Cornelia Pusch (see also the homepage of project Bali at
  1149 http://isabelle.in.tum.de/Bali/);
  1150 
  1151 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1152 Clemens Ballarin;
  1153 
  1154 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1155 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1156 Rasmussen;
  1157 
  1158 * HOL/Lattice: fundamental concepts of lattice theory and order
  1159 structures, including duals, properties of bounds versus algebraic
  1160 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1161 Theorem for complete lattices etc.; may also serve as a demonstration
  1162 for abstract algebraic reasoning using axiomatic type classes, and
  1163 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1164 
  1165 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1166 von Oheimb;
  1167 
  1168 * HOL/IMPP: extension of IMP with local variables and mutually
  1169 recursive procedures, by David von Oheimb;
  1170 
  1171 * HOL/Lambda: converted into new-style theory and document;
  1172 
  1173 * HOL/ex/Multiquote: example of multiple nested quotations and
  1174 anti-quotations -- basically a generalized version of de-Bruijn
  1175 representation; very useful in avoiding lifting of operations;
  1176 
  1177 * HOL/record: added general record equality rule to simpset; fixed
  1178 select-update simplification procedure to handle extended records as
  1179 well; admit "r" as field name;
  1180 
  1181 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1182 other numeric types and also as the identity of groups, rings, etc.;
  1183 
  1184 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1185 Types nat and int belong to this axclass;
  1186 
  1187 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1188    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1189    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1190   two terms #m*u and #n*u are replaced by #(m+n)*u
  1191     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1192   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1193     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1194 
  1195 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1196 powerful prover for predicate logic but knows nothing of clasets; see
  1197 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1198 
  1199 * HOL: new version of "case_tac" subsumes both boolean case split and
  1200 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1201 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1202 
  1203 * HOL: simplification no longer dives into case-expressions: only the
  1204 selector expression is simplified, but not the remaining arms; to
  1205 enable full simplification of case-expressions for datatype t, you may
  1206 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1207 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1208 
  1209 * HOL/recdef: the recursion equations generated by 'recdef' for
  1210 function 'f' are now called f.simps instead of f.rules; if all
  1211 termination conditions are proved automatically, these simplification
  1212 rules are added to the simpset, as in primrec; rules may be named
  1213 individually as well, resulting in a separate list of theorems for
  1214 each equation;
  1215 
  1216 * HOL/While is a new theory that provides a while-combinator. It
  1217 permits the definition of tail-recursive functions without the
  1218 provision of a termination measure. The latter is necessary once the
  1219 invariant proof rule for while is applied.
  1220 
  1221 * HOL: new (overloaded) notation for the set of elements below/above
  1222 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1223 
  1224 * HOL: theorems impI, allI, ballI bound as "strip";
  1225 
  1226 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1227 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1228 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1229 
  1230 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1231 
  1232 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1233 main HOL, but was unused);
  1234 
  1235 * HOL: fewer consts declared as global (e.g. have to refer to
  1236 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1237 
  1238 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1239 in case of overlap with user translations (e.g. judgements over
  1240 tuples); (note that the underlying logical represenation is still
  1241 bogus);
  1242 
  1243 
  1244 *** ZF ***
  1245 
  1246 * ZF: simplification automatically cancels common terms in arithmetic
  1247 expressions over nat and int;
  1248 
  1249 * ZF: new treatment of nat to minimize type-checking: all operators
  1250 coerce their operands to a natural number using the function natify,
  1251 making the algebraic laws unconditional;
  1252 
  1253 * ZF: as above, for int: operators coerce their operands to an integer
  1254 using the function intify;
  1255 
  1256 * ZF: the integer library now contains many of the usual laws for the
  1257 orderings, including $<=, and monotonicity laws for $+ and $*;
  1258 
  1259 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1260 simplification;
  1261 
  1262 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1263 to the simplifier and classical reasoner simultaneously;
  1264 
  1265 
  1266 *** General ***
  1267 
  1268 * Provers: blast_tac now handles actual object-logic rules as
  1269 assumptions; note that auto_tac uses blast_tac internally as well;
  1270 
  1271 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1272 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1273 
  1274 * Provers: delrules now handles destruct rules as well (no longer need
  1275 explicit make_elim);
  1276 
  1277 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1278   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1279 use instead the strong form,
  1280   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1281 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1282 from destruct-rules;
  1283 
  1284 * Provers: Simplifier.easy_setup provides a fast path to basic
  1285 Simplifier setup for new object-logics;
  1286 
  1287 * Pure: AST translation rules no longer require constant head on LHS;
  1288 
  1289 * Pure: improved name spaces: ambiguous output is qualified; support
  1290 for hiding of names;
  1291 
  1292 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1293 XSYMBOL_HOME; no longer need to do manual configuration in most
  1294 situations;
  1295 
  1296 * system: compression of ML heaps images may now be controlled via -c
  1297 option of isabelle and isatool usedir (currently only observed by
  1298 Poly/ML);
  1299 
  1300 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1301 useful for remote X11);
  1302 
  1303 * system: provide TAGS file for Isabelle sources;
  1304 
  1305 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1306 order;
  1307 
  1308 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1309 timing flag supersedes proof_timing and Toplevel.trace;
  1310 
  1311 * ML: new combinators |>> and |>>> for incremental transformations
  1312 with secondary results (e.g. certain theory extensions):
  1313 
  1314 * ML: PureThy.add_defs gets additional argument to indicate potential
  1315 overloading (usually false);
  1316 
  1317 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1318 results;
  1319 
  1320 
  1321 
  1322 New in Isabelle99 (October 1999)
  1323 --------------------------------
  1324 
  1325 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1326 
  1327 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1328 are no longer simplified.  (This allows the simplifier to unfold recursive
  1329 functional programs.)  To restore the old behaviour, declare
  1330 
  1331     Delcongs [if_weak_cong];
  1332 
  1333 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1334 complement;
  1335 
  1336 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1337 
  1338 * HOL/datatype: mutual_induct_tac no longer exists --
  1339   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1340 
  1341 * HOL/typedef: fixed type inference for representing set; type
  1342 arguments now have to occur explicitly on the rhs as type constraints;
  1343 
  1344 * ZF: The con_defs part of an inductive definition may no longer refer
  1345 to constants declared in the same theory;
  1346 
  1347 * HOL, ZF: the function mk_cases, generated by the inductive
  1348 definition package, has lost an argument.  To simplify its result, it
  1349 uses the default simpset instead of a supplied list of theorems.
  1350 
  1351 * HOL/List: the constructors of type list are now Nil and Cons;
  1352 
  1353 * Simplifier: the type of the infix ML functions
  1354         setSSolver addSSolver setSolver addSolver
  1355 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1356 for packaging solvers. A solver is created via
  1357         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1358 where the string argument is only a comment.
  1359 
  1360 
  1361 *** Proof tools ***
  1362 
  1363 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1364 decision procedure for linear arithmetic. Currently it is used for
  1365 types `nat', `int', and `real' in HOL (see below); it can, should and
  1366 will be instantiated for other types and logics as well.
  1367 
  1368 * The simplifier now accepts rewrite rules with flexible heads, eg
  1369      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1370   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1371   matching.
  1372 
  1373 
  1374 *** General ***
  1375 
  1376 * New Isabelle/Isar subsystem provides an alternative to traditional
  1377 tactical theorem proving; together with the ProofGeneral/isar user
  1378 interface it offers an interactive environment for developing human
  1379 readable proof documents (Isar == Intelligible semi-automated
  1380 reasoning); for further information see isatool doc isar-ref,
  1381 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1382 
  1383 * improved and simplified presentation of theories: better HTML markup
  1384 (including colors), graph views in several sizes; isatool usedir now
  1385 provides a proper interface for user theories (via -P option); actual
  1386 document preparation based on (PDF)LaTeX is available as well (for
  1387 new-style theories only); see isatool doc system for more information;
  1388 
  1389 * native support for Proof General, both for classic Isabelle and
  1390 Isabelle/Isar;
  1391 
  1392 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1393 using the graph browser tool;
  1394 
  1395 * Isabelle manuals now also available as PDF;
  1396 
  1397 * theory loader rewritten from scratch (may not be fully
  1398 bug-compatible); old loadpath variable has been replaced by show_path,
  1399 add_path, del_path, reset_path functions; new operations such as
  1400 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1401 isatool doc ref);
  1402 
  1403 * improved isatool install: option -k creates KDE application icon,
  1404 option -p DIR installs standalone binaries;
  1405 
  1406 * added ML_PLATFORM setting (useful for cross-platform installations);
  1407 more robust handling of platform specific ML images for SML/NJ;
  1408 
  1409 * the settings environment is now statically scoped, i.e. it is never
  1410 created again in sub-processes invoked from isabelle, isatool, or
  1411 Isabelle;
  1412 
  1413 * path element specification '~~' refers to '$ISABELLE_HOME';
  1414 
  1415 * in locales, the "assumes" and "defines" parts may be omitted if
  1416 empty;
  1417 
  1418 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1419 long arrows);
  1420 
  1421 * new print_mode "HTML";
  1422 
  1423 * new flag show_tags controls display of tags of theorems (which are
  1424 basically just comments that may be attached by some tools);
  1425 
  1426 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1427 mode and goal output format:
  1428 
  1429 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1430 244c244
  1431 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1432 ---
  1433 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1434 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1435 181c181
  1436 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1437 ---
  1438 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1439 
  1440 * function bind_thms stores lists of theorems (cf. bind_thm);
  1441 
  1442 * new shorthand tactics ftac, eatac, datac, fatac;
  1443 
  1444 * qed (and friends) now accept "" as result name; in that case the
  1445 theorem is not stored, but proper checks and presentation of the
  1446 result still apply;
  1447 
  1448 * theorem database now also indexes constants "Trueprop", "all",
  1449 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1450 
  1451 
  1452 *** HOL ***
  1453 
  1454 ** HOL arithmetic **
  1455 
  1456 * There are now decision procedures for linear arithmetic over nat and
  1457 int:
  1458 
  1459 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1460 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1461 are treated as atomic; subformulae not involving type `nat' or `int'
  1462 are ignored; quantified subformulae are ignored unless they are
  1463 positive universal or negative existential. The tactic has to be
  1464 invoked by hand and can be a little bit slow. In particular, the
  1465 running time is exponential in the number of occurrences of `min' and
  1466 `max', and `-' on `nat'.
  1467 
  1468 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1469 (negated) (in)equalities among the premises and the conclusion into
  1470 account (i.e. no compound formulae) and does not know about `min' and
  1471 `max', and `-' on `nat'. It is fast and is used automatically by the
  1472 simplifier.
  1473 
  1474 NB: At the moment, these decision procedures do not cope with mixed
  1475 nat/int formulae where the two parts interact, such as `m < n ==>
  1476 int(m) < int(n)'.
  1477 
  1478 * HOL/Numeral provides a generic theory of numerals (encoded
  1479 efficiently as bit strings); setup for types nat/int/real is in place;
  1480 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1481 int, existing theories and proof scripts may require a few additional
  1482 type constraints;
  1483 
  1484 * integer division and remainder can now be performed on constant
  1485 arguments;
  1486 
  1487 * many properties of integer multiplication, division and remainder
  1488 are now available;
  1489 
  1490 * An interface to the Stanford Validity Checker (SVC) is available through the
  1491 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1492 are proved automatically.  SVC must be installed separately, and its results
  1493 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1494 invocation of the underlying oracle).  For SVC see
  1495   http://verify.stanford.edu/SVC
  1496 
  1497 * IsaMakefile: the HOL-Real target now builds an actual image;
  1498 
  1499 
  1500 ** HOL misc **
  1501 
  1502 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1503 (in Isabelle/Isar) -- by Gertrud Bauer;
  1504 
  1505 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1506 analysis for assembly languages with subtypes;
  1507 
  1508 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1509 -- avoids syntactic ambiguities and treats state, transition, and
  1510 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1511 changed syntax and (many) tactics;
  1512 
  1513 * HOL/inductive: Now also handles more general introduction rules such
  1514   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1515   theorems are now maintained within the theory (maintained via the
  1516   "mono" attribute);
  1517 
  1518 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1519   (using function types) such as
  1520 
  1521   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1522 
  1523 * HOL/record: record_simproc (part of the default simpset) takes care
  1524 of selectors applied to updated records; record_split_tac is no longer
  1525 part of the default claset; update_defs may now be removed from the
  1526 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1527 
  1528   claset_ref () := claset() addSWrapper record_split_wrapper;
  1529   Delsimprocs [record_simproc]
  1530 
  1531 * HOL/typedef: fixed type inference for representing set; type
  1532 arguments now have to occur explicitly on the rhs as type constraints;
  1533 
  1534 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1535 names rather than an ML expression;
  1536 
  1537 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1538 supplied later.  Program schemes can be defined, such as
  1539     "While B C s = (if B s then While B C (C s) else s)"
  1540 where the well-founded relation can be chosen after B and C have been given.
  1541 
  1542 * HOL/List: the constructors of type list are now Nil and Cons;
  1543 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1544 course, ML tools referring to List.list.op # etc. have to be adapted;
  1545 
  1546 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1547 disabled by default; run isabelle with option -m HOL to get back to
  1548 the original Gordon/HOL-style output;
  1549 
  1550 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1551 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1552 
  1553 * HOL basic syntax simplified (more orthogonal): all variants of
  1554 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1555 Eps operator is provided as well: "SOME x. P[x]";
  1556 
  1557 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1558 
  1559 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1560 thus available for user theories;
  1561 
  1562 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1563 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1564 time;
  1565 
  1566 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1567 several times and then mp;
  1568 
  1569 
  1570 *** LK ***
  1571 
  1572 * the notation <<...>> is now available as a notation for sequences of
  1573 formulas;
  1574 
  1575 * the simplifier is now installed
  1576 
  1577 * the axiom system has been generalized (thanks to Soren Heilmann)
  1578 
  1579 * the classical reasoner now has a default rule database
  1580 
  1581 
  1582 *** ZF ***
  1583 
  1584 * new primrec section allows primitive recursive functions to be given
  1585 directly (as in HOL) over datatypes and the natural numbers;
  1586 
  1587 * new tactics induct_tac and exhaust_tac for induction (or case
  1588 analysis) over datatypes and the natural numbers;
  1589 
  1590 * the datatype declaration of type T now defines the recursor T_rec;
  1591 
  1592 * simplification automatically does freeness reasoning for datatype
  1593 constructors;
  1594 
  1595 * automatic type-inference, with AddTCs command to insert new
  1596 type-checking rules;
  1597 
  1598 * datatype introduction rules are now added as Safe Introduction rules
  1599 to the claset;
  1600 
  1601 * the syntax "if P then x else y" is now available in addition to
  1602 if(P,x,y);
  1603 
  1604 
  1605 *** Internal programming interfaces ***
  1606 
  1607 * tuned simplifier trace output; new flag debug_simp;
  1608 
  1609 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1610 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1611 
  1612 * AxClass.axclass_tac lost the theory argument;
  1613 
  1614 * tuned current_goals_markers semantics: begin / end goal avoids
  1615 printing empty lines;
  1616 
  1617 * removed prs and prs_fn hook, which was broken because it did not
  1618 include \n in its semantics, forcing writeln to add one
  1619 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1620 string -> unit if you really want to output text without newline;
  1621 
  1622 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1623 plain output, interface builders may have to enable 'isabelle_font'
  1624 mode to get Isabelle font glyphs as before;
  1625 
  1626 * refined token_translation interface; INCOMPATIBILITY: output length
  1627 now of type real instead of int;
  1628 
  1629 * theory loader actions may be traced via new ThyInfo.add_hook
  1630 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1631 your own database of information attached to *whole* theories -- as
  1632 opposed to intra-theory data slots offered via TheoryDataFun;
  1633 
  1634 * proper handling of dangling sort hypotheses (at last!);
  1635 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1636 extra sort hypotheses that can be witnessed from the type signature;
  1637 the force_strip_shyps flag is gone, any remaining shyps are simply
  1638 left in the theorem (with a warning issued by strip_shyps_warning);
  1639 
  1640 
  1641 
  1642 New in Isabelle98-1 (October 1998)
  1643 ----------------------------------
  1644 
  1645 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1646 
  1647 * several changes of automated proof tools;
  1648 
  1649 * HOL: major changes to the inductive and datatype packages, including
  1650 some minor incompatibilities of theory syntax;
  1651 
  1652 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1653 called `inj_on';
  1654 
  1655 * HOL: removed duplicate thms in Arith:
  1656   less_imp_add_less  should be replaced by  trans_less_add1
  1657   le_imp_add_le      should be replaced by  trans_le_add1
  1658 
  1659 * HOL: unary minus is now overloaded (new type constraints may be
  1660 required);
  1661 
  1662 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1663 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1664 now taken as an integer constant.
  1665 
  1666 * Pure: ML function 'theory_of' renamed to 'theory';
  1667 
  1668 
  1669 *** Proof tools ***
  1670 
  1671 * Simplifier:
  1672   1. Asm_full_simp_tac is now more aggressive.
  1673      1. It will sometimes reorient premises if that increases their power to
  1674         simplify.
  1675      2. It does no longer proceed strictly from left to right but may also
  1676         rotate premises to achieve further simplification.
  1677      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1678      old Asm_full_simp_tac in that it does not rotate premises.
  1679   2. The simplifier now knows a little bit about nat-arithmetic.
  1680 
  1681 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1682 allows for selected deletion of wrappers, by introduction of names for
  1683 wrapper functionals.  This implies that addbefore, addSbefore,
  1684 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1685 and that adding two tactics with the same name overwrites the first
  1686 one (emitting a warning).
  1687   type wrapper = (int -> tactic) -> (int -> tactic)
  1688   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1689   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1690   delWrapper, delSWrapper: claset *  string            -> claset
  1691   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1692 
  1693 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1694 semantics; addbefore now affects only the unsafe part of step_tac
  1695 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1696 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1697 by Force_tac;
  1698 
  1699 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1700 compWrapper; added safe wrapper (and access functions for it);
  1701 
  1702 * HOL/split_all_tac is now much faster and fails if there is nothing
  1703 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1704 and the names of the automatically generated variables have changed.
  1705 split_all_tac has moved within claset() from unsafe wrappers to safe
  1706 wrappers, which means that !!-bound variables are split much more
  1707 aggressively, and safe_tac and clarify_tac now split such variables.
  1708 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1709 Note: the same holds for record_split_tac, which does the job of
  1710 split_all_tac for record fields.
  1711 
  1712 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1713 permanently to the default simpset using Addsplits just like
  1714 Addsimps. They can be removed via Delsplits just like
  1715 Delsimps. Lower-case versions are also available.
  1716 
  1717 * HOL/Simplifier: The rule split_if is now part of the default
  1718 simpset. This means that the simplifier will eliminate all occurrences
  1719 of if-then-else in the conclusion of a goal. To prevent this, you can
  1720 either remove split_if completely from the default simpset by
  1721 `Delsplits [split_if]' or remove it in a specific call of the
  1722 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1723 other case splitting rules to/from the default simpset: every datatype
  1724 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1725 t is the name of the datatype).
  1726 
  1727 * Classical reasoner / Simplifier combination: new force_tac (and
  1728 derivatives Force_tac, force) combines rewriting and classical
  1729 reasoning (and whatever other tools) similarly to auto_tac, but is
  1730 aimed to solve the given subgoal completely.
  1731 
  1732 
  1733 *** General ***
  1734 
  1735 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1736 and `goalw': the theory is no longer needed as an explicit argument -
  1737 the current theory context is used; assumptions are no longer returned
  1738 at the ML-level unless one of them starts with ==> or !!; it is
  1739 recommended to convert to these new commands using isatool fixgoal
  1740 (backup your sources first!);
  1741 
  1742 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1743 the current theory context, and 'theory' to lookup stored theories;
  1744 
  1745 * new theory section 'locale' for declaring constants, assumptions and
  1746 definitions that have local scope;
  1747 
  1748 * new theory section 'nonterminals' for purely syntactic types;
  1749 
  1750 * new theory section 'setup' for generic ML setup functions
  1751 (e.g. package initialization);
  1752 
  1753 * the distribution now includes Isabelle icons: see
  1754 lib/logo/isabelle-{small,tiny}.xpm;
  1755 
  1756 * isatool install - install binaries with absolute references to
  1757 ISABELLE_HOME/bin;
  1758 
  1759 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1760 
  1761 * print mode 'emacs' reserved for Isamode;
  1762 
  1763 * support multiple print (ast) translations per constant name;
  1764 
  1765 * theorems involving oracles are now printed with a suffixed [!];
  1766 
  1767 
  1768 *** HOL ***
  1769 
  1770 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1771 
  1772 * HOL/inductive package reorganized and improved: now supports mutual
  1773 definitions such as
  1774 
  1775   inductive EVEN ODD
  1776     intrs
  1777       null "0 : EVEN"
  1778       oddI "n : EVEN ==> Suc n : ODD"
  1779       evenI "n : ODD ==> Suc n : EVEN"
  1780 
  1781 new theorem list "elims" contains an elimination rule for each of the
  1782 recursive sets; inductive definitions now handle disjunctive premises
  1783 correctly (also ZF);
  1784 
  1785 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1786 "mutual_induct" no longer exists - the induction rule is always
  1787 contained in "induct";
  1788 
  1789 
  1790 * HOL/datatype package re-implemented and greatly improved: now
  1791 supports mutually recursive datatypes such as
  1792 
  1793   datatype
  1794     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1795             | SUM ('a aexp) ('a aexp)
  1796             | DIFF ('a aexp) ('a aexp)
  1797             | NUM 'a
  1798   and
  1799     'a bexp = LESS ('a aexp) ('a aexp)
  1800             | AND ('a bexp) ('a bexp)
  1801             | OR ('a bexp) ('a bexp)
  1802 
  1803 as well as indirectly recursive datatypes such as
  1804 
  1805   datatype
  1806     ('a, 'b) term = Var 'a
  1807                   | App 'b ((('a, 'b) term) list)
  1808 
  1809 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1810 induction on mutually / indirectly recursive datatypes.
  1811 
  1812 Primrec equations are now stored in theory and can be accessed via
  1813 <function_name>.simps.
  1814 
  1815 INCOMPATIBILITIES:
  1816 
  1817   - Theories using datatypes must now have theory Datatype as an
  1818     ancestor.
  1819   - The specific <typename>.induct_tac no longer exists - use the
  1820     generic induct_tac instead.
  1821   - natE has been renamed to nat.exhaust - use exhaust_tac
  1822     instead of res_inst_tac ... natE. Note that the variable
  1823     names in nat.exhaust differ from the names in natE, this
  1824     may cause some "fragile" proofs to fail.
  1825   - The theorems split_<typename>_case and split_<typename>_case_asm
  1826     have been renamed to <typename>.split and <typename>.split_asm.
  1827   - Since default sorts of type variables are now handled correctly,
  1828     some datatype definitions may have to be annotated with explicit
  1829     sort constraints.
  1830   - Primrec definitions no longer require function name and type
  1831     of recursive argument.
  1832 
  1833 Consider using isatool fixdatatype to adapt your theories and proof
  1834 scripts to the new package (backup your sources first!).
  1835 
  1836 
  1837 * HOL/record package: considerably improved implementation; now
  1838 includes concrete syntax for record types, terms, updates; theorems
  1839 for surjective pairing and splitting !!-bound record variables; proof
  1840 support is as follows:
  1841 
  1842   1) standard conversions (selectors or updates applied to record
  1843 constructor terms) are part of the standard simpset;
  1844 
  1845   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1846 made part of standard simpset and claset via addIffs;
  1847 
  1848   3) a tactic for record field splitting (record_split_tac) is part of
  1849 the standard claset (addSWrapper);
  1850 
  1851 To get a better idea about these rules you may retrieve them via
  1852 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1853 the name of your record type.
  1854 
  1855 The split tactic 3) conceptually simplifies by the following rule:
  1856 
  1857   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1858 
  1859 Thus any record variable that is bound by meta-all will automatically
  1860 blow up into some record constructor term, consequently the
  1861 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1862 solve record problems automatically.
  1863 
  1864 
  1865 * reorganized the main HOL image: HOL/Integ and String loaded by
  1866 default; theory Main includes everything;
  1867 
  1868 * automatic simplification of integer sums and comparisons, using cancellation;
  1869 
  1870 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1871 
  1872 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1873 
  1874 * many new identities for unions, intersections, set difference, etc.;
  1875 
  1876 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1877 called split_if, split_split, split_sum_case and split_nat_case (to go
  1878 with add/delsplits);
  1879 
  1880 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1881 (?x::unit) = (); this is made part of the default simpset, which COULD
  1882 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1883 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1884 unit_abs_eta_conv is added in order to counter the effect of
  1885 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1886 %u.f();
  1887 
  1888 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1889 makes more sense);
  1890 
  1891 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1892   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1893   disjointness reasoning but breaking a few old proofs.
  1894 
  1895 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1896 to 'converse' from 'inverse' (for compatibility with ZF and some
  1897 literature);
  1898 
  1899 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1900 the well-founded relation;
  1901 
  1902 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1903     Compl A.  The "Compl" syntax remains available as input syntax for this
  1904     release ONLY.
  1905 
  1906 * HOL/Update: new theory of function updates:
  1907     f(a:=b) == %x. if x=a then b else f x
  1908 may also be iterated as in f(a:=b,c:=d,...);
  1909 
  1910 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1911 
  1912 * HOL/List:
  1913   - new function list_update written xs[i:=v] that updates the i-th
  1914     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1915   - new function `upt' written [i..j(] which generates the list
  1916     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1917     bound write [i..j], which is a shorthand for [i..j+1(].
  1918   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1919 
  1920 * HOL/Arith:
  1921   - removed 'pred' (predecessor) function;
  1922   - generalized some theorems about n-1;
  1923   - many new laws about "div" and "mod";
  1924   - new laws about greatest common divisors (see theory ex/Primes);
  1925 
  1926 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1927 instead of "inverse";
  1928 
  1929 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1930   of the multiset ordering;
  1931 
  1932 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1933   (not included by default);
  1934 
  1935 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1936 
  1937 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1938   programs, i.e. different program variables may have different types.
  1939 
  1940 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1941   [previously, this check worked only if the rewrite rule was unconditional]
  1942   Now rew can involve either definitions or equalities (either == or =).
  1943 
  1944 
  1945 *** ZF ***
  1946 
  1947 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1948   only the theorems proved on ZF.ML;
  1949 
  1950 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1951   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1952   disjointness reasoning but breaking a few old proofs.
  1953 
  1954 * ZF/Update: new theory of function updates
  1955     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1956   may also be iterated as in f(a:=b,c:=d,...);
  1957 
  1958 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1959 
  1960 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1961   [previously, this check worked only if the rewrite rule was unconditional]
  1962   Now rew can involve either definitions or equalities (either == or =).
  1963 
  1964 * case_tac provided for compatibility with HOL
  1965     (like the old excluded_middle_tac, but with subgoals swapped)
  1966 
  1967 
  1968 *** Internal programming interfaces ***
  1969 
  1970 * Pure: several new basic modules made available for general use, see
  1971 also src/Pure/README;
  1972 
  1973 * improved the theory data mechanism to support encapsulation (data
  1974 kind name replaced by private Object.kind, acting as authorization
  1975 key); new type-safe user interface via functor TheoryDataFun; generic
  1976 print_data function becomes basically useless;
  1977 
  1978 * removed global_names compatibility flag -- all theory declarations
  1979 are qualified by default;
  1980 
  1981 * module Pure/Syntax now offers quote / antiquote translation
  1982 functions (useful for Hoare logic etc. with implicit dependencies);
  1983 see HOL/ex/Antiquote for an example use;
  1984 
  1985 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1986 cterm -> thm;
  1987 
  1988 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1989 subgoal;
  1990 
  1991 * Display.print_goals function moved to Locale.print_goals;
  1992 
  1993 * standard print function for goals supports current_goals_markers
  1994 variable for marking begin of proof, end of proof, start of goal; the
  1995 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1996 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1997 for example;
  1998 
  1999 
  2000 
  2001 New in Isabelle98 (January 1998)
  2002 --------------------------------
  2003 
  2004 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2005 
  2006 * changed lexical syntax of terms / types: dots made part of long
  2007 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2008 
  2009 * simpset (and claset) reference variable replaced by functions
  2010 simpset / simpset_ref;
  2011 
  2012 * no longer supports theory aliases (via merge) and non-trivial
  2013 implicit merge of thms' signatures;
  2014 
  2015 * most internal names of constants changed due to qualified names;
  2016 
  2017 * changed Pure/Sequence interface (see Pure/seq.ML);
  2018 
  2019 
  2020 *** General Changes ***
  2021 
  2022 * hierachically structured name spaces (for consts, types, axms, thms
  2023 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2024 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2025 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2026 long_names for fully qualified output names; NOTE: ML programs
  2027 (special tactics, packages etc.) referring to internal names may have
  2028 to be adapted to cope with fully qualified names; in case of severe
  2029 backward campatibility problems try setting 'global_names' at compile
  2030 time to have enrything declared within a flat name space; one may also
  2031 fine tune name declarations in theories via the 'global' and 'local'
  2032 section;
  2033 
  2034 * reimplemented the implicit simpset and claset using the new anytype
  2035 data filed in signatures; references simpset:simpset ref etc. are
  2036 replaced by functions simpset:unit->simpset and
  2037 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2038 to patch your ML files accordingly;
  2039 
  2040 * HTML output now includes theory graph data for display with Java
  2041 applet or isatool browser; data generated automatically via isatool
  2042 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2043 
  2044 * defs may now be conditional; improved rewrite_goals_tac to handle
  2045 conditional equations;
  2046 
  2047 * defs now admits additional type arguments, using TYPE('a) syntax;
  2048 
  2049 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2050 creates a new theory node; implicit merge of thms' signatures is
  2051 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2052 transfer:theory->thm->thm in (rare) cases;
  2053 
  2054 * improved handling of draft signatures / theories; draft thms (and
  2055 ctyps, cterms) are automatically promoted to real ones;
  2056 
  2057 * slightly changed interfaces for oracles: admit many per theory, named
  2058 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2059 
  2060 * print_goals: optional output of const types (set show_consts and
  2061 show_types);
  2062 
  2063 * improved output of warnings (###) and errors (***);
  2064 
  2065 * subgoal_tac displays a warning if the new subgoal has type variables;
  2066 
  2067 * removed old README and Makefiles;
  2068 
  2069 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2070 
  2071 * removed obsolete init_pps and init_database;
  2072 
  2073 * deleted the obsolete tactical STATE, which was declared by
  2074     fun STATE tacfun st = tacfun st st;
  2075 
  2076 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2077 (which abbreviates $HOME);
  2078 
  2079 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2080 use isatool fixseq to adapt your ML programs (this works for fully
  2081 qualified references to the Sequence structure only!);
  2082 
  2083 * use_thy no longer requires writable current directory; it always
  2084 reloads .ML *and* .thy file, if either one is out of date;
  2085 
  2086 
  2087 *** Classical Reasoner ***
  2088 
  2089 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2090 tactics that use classical reasoning to simplify a subgoal without
  2091 splitting it into several subgoals;
  2092 
  2093 * Safe_tac: like safe_tac but uses the default claset;
  2094 
  2095 
  2096 *** Simplifier ***
  2097 
  2098 * added simplification meta rules:
  2099     (asm_)(full_)simplify: simpset -> thm -> thm;
  2100 
  2101 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2102 logics (again);
  2103 
  2104 * added prems argument to simplification procedures;
  2105 
  2106 * HOL, FOL, ZF: added infix function `addsplits':
  2107   instead of `<simpset> setloop (split_tac <thms>)'
  2108   you can simply write `<simpset> addsplits <thms>'
  2109 
  2110 
  2111 *** Syntax ***
  2112 
  2113 * TYPE('a) syntax for type reflection terms;
  2114 
  2115 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2116 
  2117 * pretty printer: changed order of mixfix annotation preference (again!);
  2118 
  2119 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2120 
  2121 
  2122 *** HOL ***
  2123 
  2124 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2125   with `addloop' of the simplifier to faciliate case splitting in premises.
  2126 
  2127 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2128 
  2129 * HOL/Auth: new protocol proofs including some for the Internet
  2130   protocol TLS;
  2131 
  2132 * HOL/Map: new theory of `maps' a la VDM;
  2133 
  2134 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2135 cancelling out common nat summands from =, <, <= (in)equalities, or
  2136 differences; simplification procedures nat_cancel_factor for
  2137 cancelling common factor from =, <, <= (in)equalities over natural
  2138 sums; nat_cancel contains both kinds of procedures, it is installed by
  2139 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2140 
  2141 * HOL/simplifier: terms of the form
  2142   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2143   are rewritten to
  2144   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2145   and those of the form
  2146   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2147   are rewritten to
  2148   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2149 
  2150 * HOL/datatype
  2151   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2152 
  2153   P(t_case f1 ... fn x) =
  2154      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2155         ...
  2156        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2157      )
  2158 
  2159   and a theorem `split_t_case_asm' of the form
  2160 
  2161   P(t_case f1 ... fn x) =
  2162     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2163         ...
  2164        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2165      )
  2166   which can be added to a simpset via `addsplits'. The existing theorems
  2167   expand_list_case and expand_option_case have been renamed to
  2168   split_list_case and split_option_case.
  2169 
  2170 * HOL/Arithmetic:
  2171   - `pred n' is automatically converted to `n-1'.
  2172     Users are strongly encouraged not to use `pred' any longer,
  2173     because it will disappear altogether at some point.
  2174   - Users are strongly encouraged to write "0 < n" rather than
  2175     "n ~= 0". Theorems and proof tools have been modified towards this
  2176     `standard'.
  2177 
  2178 * HOL/Lists:
  2179   the function "set_of_list" has been renamed "set" (and its theorems too);
  2180   the function "nth" now takes its arguments in the reverse order and
  2181   has acquired the infix notation "!" as in "xs!n".
  2182 
  2183 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2184 
  2185 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2186   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2187 
  2188 * HOL/record: extensible records with schematic structural subtyping
  2189 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2190 still lacks various theorems and concrete record syntax;
  2191 
  2192 
  2193 *** HOLCF ***
  2194 
  2195 * removed "axioms" and "generated by" sections;
  2196 
  2197 * replaced "ops" section by extended "consts" section, which is capable of
  2198   handling the continuous function space "->" directly;
  2199 
  2200 * domain package:
  2201   . proves theorems immediately and stores them in the theory,
  2202   . creates hierachical name space,
  2203   . now uses normal mixfix annotations (instead of cinfix...),
  2204   . minor changes to some names and values (for consistency),
  2205   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2206   . separator between mutual domain defs: changed "," to "and",
  2207   . improved handling of sort constraints;  now they have to
  2208     appear on the left-hand side of the equations only;
  2209 
  2210 * fixed LAM <x,y,zs>.b syntax;
  2211 
  2212 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2213 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2214 
  2215 
  2216 *** FOL and ZF ***
  2217 
  2218 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2219   with `addloop' of the simplifier to faciliate case splitting in premises.
  2220 
  2221 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2222 in HOL, they strip ALL and --> from proved theorems;
  2223 
  2224 
  2225 
  2226 New in Isabelle94-8 (May 1997)
  2227 ------------------------------
  2228 
  2229 *** General Changes ***
  2230 
  2231 * new utilities to build / run / maintain Isabelle etc. (in parts
  2232 still somewhat experimental); old Makefiles etc. still functional;
  2233 
  2234 * new 'Isabelle System Manual';
  2235 
  2236 * INSTALL text, together with ./configure and ./build scripts;
  2237 
  2238 * reimplemented type inference for greater efficiency, better error
  2239 messages and clean internal interface;
  2240 
  2241 * prlim command for dealing with lots of subgoals (an easier way of
  2242 setting goals_limit);
  2243 
  2244 
  2245 *** Syntax ***
  2246 
  2247 * supports alternative (named) syntax tables (parser and pretty
  2248 printer); internal interface is provided by add_modesyntax(_i);
  2249 
  2250 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2251 be used in conjunction with the Isabelle symbol font; uses the
  2252 "symbols" syntax table;
  2253 
  2254 * added token_translation interface (may translate name tokens in
  2255 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2256 the current print_mode); IMPORTANT: user print translation functions
  2257 are responsible for marking newly introduced bounds
  2258 (Syntax.mark_boundT);
  2259 
  2260 * token translations for modes "xterm" and "xterm_color" that display
  2261 names in bold, underline etc. or colors (which requires a color
  2262 version of xterm);
  2263 
  2264 * infixes may now be declared with names independent of their syntax;
  2265 
  2266 * added typed_print_translation (like print_translation, but may
  2267 access type of constant);
  2268 
  2269 
  2270 *** Classical Reasoner ***
  2271 
  2272 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2273 some limitations.  Blast_tac...
  2274   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2275   + ignores elimination rules that don't have the correct format
  2276         (the conclusion MUST be a formula variable)
  2277   + ignores types, which can make HOL proofs fail
  2278   + rules must not require higher-order unification, e.g. apply_type in ZF
  2279     [message "Function Var's argument not a bound variable" relates to this]
  2280   + its proof strategy is more general but can actually be slower
  2281 
  2282 * substitution with equality assumptions no longer permutes other
  2283 assumptions;
  2284 
  2285 * minor changes in semantics of addafter (now called addaltern); renamed
  2286 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2287 (and access functions for it);
  2288 
  2289 * improved combination of classical reasoner and simplifier:
  2290   + functions for handling clasimpsets
  2291   + improvement of addss: now the simplifier is called _after_ the
  2292     safe steps.
  2293   + safe variant of addss called addSss: uses safe simplifications
  2294     _during_ the safe steps. It is more complete as it allows multiple
  2295     instantiations of unknowns (e.g. with slow_tac).
  2296 
  2297 *** Simplifier ***
  2298 
  2299 * added interface for simplification procedures (functions that
  2300 produce *proven* rewrite rules on the fly, depending on current
  2301 redex);
  2302 
  2303 * ordering on terms as parameter (used for ordered rewriting);
  2304 
  2305 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2306 
  2307 * the solver is now split into a safe and an unsafe part.
  2308 This should be invisible for the normal user, except that the
  2309 functions setsolver and addsolver have been renamed to setSolver and
  2310 addSolver; added safe_asm_full_simp_tac;
  2311 
  2312 
  2313 *** HOL ***
  2314 
  2315 * a generic induction tactic `induct_tac' which works for all datatypes and
  2316 also for type `nat';
  2317 
  2318 * a generic case distinction tactic `exhaust_tac' which works for all
  2319 datatypes and also for type `nat';
  2320 
  2321 * each datatype comes with a function `size';
  2322 
  2323 * patterns in case expressions allow tuple patterns as arguments to
  2324 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2325 
  2326 * primrec now also works with type nat;
  2327 
  2328 * recdef: a new declaration form, allows general recursive functions to be
  2329 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2330 
  2331 * the constant for negation has been renamed from "not" to "Not" to
  2332 harmonize with FOL, ZF, LK, etc.;
  2333 
  2334 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2335 infinite lists;
  2336 
  2337 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2338 
  2339 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2340 problems in commutative rings, using axiomatic type classes for + and *;
  2341 
  2342 * more examples in HOL/MiniML and HOL/Auth;
  2343 
  2344 * more default rewrite rules for quantifiers, union/intersection;
  2345 
  2346 * a new constant `arbitrary == @x.False';
  2347 
  2348 * HOLCF/IOA replaces old HOL/IOA;
  2349 
  2350 * HOLCF changes: derived all rules and arities
  2351   + axiomatic type classes instead of classes
  2352   + typedef instead of faking type definitions
  2353   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2354   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2355   + eliminated the types void, one, tr
  2356   + use unit lift and bool lift (with translations) instead of one and tr
  2357   + eliminated blift from Lift3.thy (use Def instead of blift)
  2358   all eliminated rules are derived as theorems --> no visible changes ;
  2359 
  2360 
  2361 *** ZF ***
  2362 
  2363 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2364 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2365 as ZF_cs addSIs [equalityI];
  2366 
  2367 
  2368 
  2369 New in Isabelle94-7 (November 96)
  2370 ---------------------------------
  2371 
  2372 * allowing negative levels (as offsets) in prlev and choplev;
  2373 
  2374 * super-linear speedup for large simplifications;
  2375 
  2376 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2377 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2378 FAIL); can suppress it using the command Delsimps (ex_simps @
  2379 all_simps); De Morgan laws are also now included, by default;
  2380 
  2381 * improved printing of ==>  :  ~:
  2382 
  2383 * new object-logic "Sequents" adds linear logic, while replacing LK
  2384 and Modal (thanks to Sara Kalvala);
  2385 
  2386 * HOL/Auth: correctness proofs for authentication protocols;
  2387 
  2388 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2389 examples on HOL/Auth);
  2390 
  2391 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2392 the rewriter and classical reasoner simultaneously;
  2393 
  2394 * function uresult no longer returns theorems in "standard" format;
  2395 regain previous version by: val uresult = standard o uresult;
  2396 
  2397 
  2398 
  2399 New in Isabelle94-6
  2400 -------------------
  2401 
  2402 * oracles -- these establish an interface between Isabelle and trusted
  2403 external reasoners, which may deliver results as theorems;
  2404 
  2405 * proof objects (in particular record all uses of oracles);
  2406 
  2407 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2408 
  2409 * "constdefs" section in theory files;
  2410 
  2411 * "primrec" section (HOL) no longer requires names;
  2412 
  2413 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2414 
  2415 
  2416 
  2417 New in Isabelle94-5
  2418 -------------------
  2419 
  2420 * reduced space requirements;
  2421 
  2422 * automatic HTML generation from theories;
  2423 
  2424 * theory files no longer require "..." (quotes) around most types;
  2425 
  2426 * new examples, including two proofs of the Church-Rosser theorem;
  2427 
  2428 * non-curried (1994) version of HOL is no longer distributed;
  2429 
  2430 
  2431 
  2432 New in Isabelle94-4
  2433 -------------------
  2434 
  2435 * greatly reduced space requirements;
  2436 
  2437 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2438 
  2439 * searchable theorem database (see the section "Retrieving theorems" on
  2440 page 8 of the Reference Manual);
  2441 
  2442 * new examples, including Grabczewski's monumental case study of the
  2443 Axiom of Choice;
  2444 
  2445 * The previous version of HOL renamed to Old_HOL;
  2446 
  2447 * The new version of HOL (previously called CHOL) uses a curried syntax
  2448 for functions.  Application looks like f a b instead of f(a,b);
  2449 
  2450 * Mutually recursive inductive definitions finally work in HOL;
  2451 
  2452 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2453 translates to the operator "split";
  2454 
  2455 
  2456 
  2457 New in Isabelle94-3
  2458 -------------------
  2459 
  2460 * new infix operator, addss, allowing the classical reasoner to
  2461 perform simplification at each step of its search.  Example:
  2462         fast_tac (cs addss ss)
  2463 
  2464 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2465 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2466 look like (a,b) instead of <a,b>;
  2467 
  2468 * PLEASE NOTE: CHOL will eventually replace HOL!
  2469 
  2470 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2471 It translates to the operator "split".  A new theory of integers is available;
  2472 
  2473 * In ZF, integer numerals now denote two's-complement binary integers.
  2474 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2475 
  2476 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2477 of the Axiom of Choice;
  2478 
  2479 
  2480 
  2481 New in Isabelle94-2
  2482 -------------------
  2483 
  2484 * Significantly faster resolution;
  2485 
  2486 * the different sections in a .thy file can now be mixed and repeated
  2487 freely;
  2488 
  2489 * Database of theorems for FOL, HOL and ZF.  New
  2490 commands including qed, qed_goal and bind_thm store theorems in the database.
  2491 
  2492 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2493 a given theory (thms_of), or find out what theory a theorem was proved in
  2494 (theory_of_thm);
  2495 
  2496 * Bugs fixed in the inductive definition and datatype packages;
  2497 
  2498 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2499 and HOL_dup_cs obsolete;
  2500 
  2501 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2502 have been removed;
  2503 
  2504 * Simpler definition of function space in ZF;
  2505 
  2506 * new results about cardinal and ordinal arithmetic in ZF;
  2507 
  2508 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2509 types;
  2510 
  2511 
  2512 $Id$