NEWS
author wenzelm
Tue Feb 13 22:51:08 2001 +0100 (2001-02-13)
changeset 11112 2fea4923864f
parent 11097 c1be9f2dff4c
child 11124 5b97a468b46d
permissions -rw-r--r--
tuned;
     1 
     2 Isabelle NEWS -- history user-relevant changes
     3 ==============================================
     4 
     5 New in Isabelle99-2 (February 2001)
     6 -----------------------------------
     7 
     8 *** Overview of INCOMPATIBILITIES ***
     9 
    10 * HOL: inductive package no longer splits induction rule aggressively,
    11 but only as far as specified by the introductions given; the old
    12 format may recovered via ML function complete_split_rule or attribute
    13 'split_rule (complete)';
    14 
    15 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
    16 gfp_Tarski to gfp_unfold;
    17 
    18 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
    19 
    20 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
    21 relation); infix "^^" has been renamed "``"; infix "``" has been
    22 renamed "`"; "univalent" has been renamed "single_valued";
    23 
    24 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
    25 operation;
    26 
    27 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
    28 
    29 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
    30 
    31 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
    32 consequence, it is no longer monotonic wrt. the local goal context
    33 (which is now passed through the inductive cases);
    34 
    35 * Document preparation: renamed standard symbols \<ll> to \<lless> and
    36 \<gg> to \<ggreater>;
    37 
    38 
    39 *** Document preparation ***
    40 
    41 * \isabellestyle{NAME} selects version of Isabelle output (currently
    42 available: are "it" for near math-mode best-style output, "sl" for
    43 slanted text style, and "tt" for plain type-writer; if no
    44 \isabellestyle command is given, output is according to slanted
    45 type-writer);
    46 
    47 * support sub/super scripts (for single symbols only), input syntax is
    48 like this: "A\<^sup>*" or "A\<^sup>\<star>";
    49 
    50 * some more standard symbols; see Appendix A of the system manual for
    51 the complete list of symbols defined in isabellesym.sty;
    52 
    53 * improved isabelle style files; more abstract symbol implementation
    54 (should now use \isamath{...} and \isatext{...} in custom symbol
    55 definitions);
    56 
    57 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
    58 state; Note that presentation of goal states does not conform to
    59 actual human-readable proof documents.  Please do not include goal
    60 states into document output unless you really know what you are doing!
    61 
    62 * proper indentation of antiquoted output with proportional LaTeX
    63 fonts;
    64 
    65 * no_document ML operator temporarily disables LaTeX document
    66 generation;
    67 
    68 * isatool unsymbolize tunes sources for plain ASCII communication;
    69 
    70 
    71 *** Isar ***
    72 
    73 * Pure: Isar now suffers initial goal statements to contain unbound
    74 schematic variables (this does not conform to actual readable proof
    75 documents, due to unpredictable outcome and non-compositional proof
    76 checking); users who know what they are doing may use schematic goals
    77 for Prolog-style synthesis of proven results;
    78 
    79 * Pure: assumption method (an implicit finishing) now handles actual
    80 rules as well;
    81 
    82 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
    83 initial goal, declare "that" only as Pure intro (only for single
    84 steps); the "that" rule assumption may now be involved in implicit
    85 finishing, thus ".." becomes a feasible for trivial obtains;
    86 
    87 * Pure: default proof step now includes 'intro_classes'; thus trivial
    88 instance proofs may be performed by "..";
    89 
    90 * Pure: ?thesis / ?this / "..." now work for pure meta-level
    91 statements as well;
    92 
    93 * Pure: more robust selection of calculational rules;
    94 
    95 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
    96 rule (as well as the assumption rule);
    97 
    98 * Pure: 'thm_deps' command visualizes dependencies of theorems and
    99 lemmas, using the graph browser tool;
   100 
   101 * Pure: predict failure of "show" in interactive mode;
   102 
   103 * Pure: 'thms_containing' now takes actual terms as arguments;
   104 
   105 * HOL: improved method 'induct' --- now handles non-atomic goals
   106 (potential INCOMPATIBILITY); tuned error handling;
   107 
   108 * HOL: cases and induct rules now provide explicit hints about the
   109 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   110 any remaining facts are inserted into the goal verbatim;
   111 
   112 * HOL: local contexts (aka cases) may now contain term bindings as
   113 well; the 'cases' and 'induct' methods new provide a ?case binding for
   114 the result to be shown in each case;
   115 
   116 * HOL: added 'recdef_tc' command;
   117 
   118 * isatool convert assists in eliminating legacy ML scripts;
   119 
   120 
   121 *** HOL ***
   122 
   123 * HOL/Library: a collection of generic theories to be used together
   124 with main HOL; the theory loader path already includes this directory
   125 by default; the following existing theories have been moved here:
   126 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   127 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   128 
   129 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   130 modelling and verification task performed in Isabelle/HOL +
   131 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   132 
   133 * HOL/Algebra: special summation operator SUM no longer exists, it has
   134 been replaced by setsum; infix 'assoc' now has priority 50 (like
   135 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   136 'domain', this makes the theory consistent with mathematical
   137 literature;
   138 
   139 * HOL basics: added overloaded operations "inverse" and "divide"
   140 (infix "/"), syntax for generic "abs" operation, generic summation
   141 operator \<Sum>;
   142 
   143 * HOL/typedef: simplified package, provide more useful rules (see also
   144 HOL/subset.thy);
   145 
   146 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   147 now expressed as a proper nested rule (old-style tactic scripts may
   148 require atomize_strip_tac to cope with non-atomic premises);
   149 
   150 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   151 to "split_conv" (old name still available for compatibility);
   152 
   153 * HOL: improved concrete syntax for strings (e.g. allows translation
   154 rules with string literals);
   155 
   156 * HOL-Hyperreal: a new target, extending HOL-Real with the hyperreals
   157 and Fleuriot's mechanization of analysis;
   158 
   159 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   160 
   161 
   162 *** CTT ***
   163 
   164 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   165 "lam" is displayed as TWO lambda-symbols
   166 
   167 * CTT: theory Main now available, containing everything (that is, Bool
   168 and Arith);
   169 
   170 
   171 *** General ***
   172 
   173 * system: support Poly/ML 4.0;
   174 
   175 * Pure: the Simplifier has been implemented properly as a derived rule
   176 outside of the actual kernel (at last!); the overall performance
   177 penalty in practical applications is about 50%, while reliability of
   178 the Isabelle inference kernel has been greatly improved;
   179 
   180 * print modes "brackets" and "no_brackets" control output of nested =>
   181 (types) and ==> (props); the default behaviour is "brackets";
   182 
   183 * Provers: fast_tac (and friends) now handle actual object-logic rules
   184 as assumptions as well;
   185 
   186 
   187 
   188 New in Isabelle99-1 (October 2000)
   189 ----------------------------------
   190 
   191 *** Overview of INCOMPATIBILITIES ***
   192 
   193 * HOL: simplification of natural numbers is much changed; to partly
   194 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   195 issue the following ML commands:
   196 
   197   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   198   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   199 
   200 * HOL: simplification no longer dives into case-expressions; this is
   201 controlled by "t.weak_case_cong" for each datatype t;
   202 
   203 * HOL: nat_less_induct renamed to less_induct;
   204 
   205 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   206 fixsome to patch .thy and .ML sources automatically;
   207 
   208   select_equality  -> some_equality
   209   select_eq_Ex     -> some_eq_ex
   210   selectI2EX       -> someI2_ex
   211   selectI2         -> someI2
   212   selectI          -> someI
   213   select1_equality -> some1_equality
   214   Eps_sym_eq       -> some_sym_eq_trivial
   215   Eps_eq           -> some_eq_trivial
   216 
   217 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   218 
   219 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   220 instead);
   221 
   222 * HOL: the recursion equations generated by 'recdef' are now called
   223 f.simps instead of f.rules;
   224 
   225 * HOL: qed_spec_mp now also handles bounded ALL as well;
   226 
   227 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   228 sometimes be needed;
   229 
   230 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   231 
   232 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   233 
   234 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   235 product is now "<*>" instead of "Times"; the lexicographic product is
   236 now "<*lex*>" instead of "**";
   237 
   238 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   239 of main HOL, but was unused); better use HOL's datatype package;
   240 
   241 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   242 the old syntax may be recovered as follows:
   243 
   244   syntax (symbols)
   245     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   246       (infixl "\\<oplus>" 100)
   247 
   248 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   249 
   250 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   251 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   252 internally;
   253 
   254 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   255 changed from A/r to A//r;
   256 
   257 * ZF: new treatment of arithmetic (nat & int) may break some old
   258 proofs;
   259 
   260 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   261 rulify -> rule_format, elimify -> elim_format, ...);
   262 
   263 * Isar/Provers: intro/elim/dest attributes changed; renamed
   264 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   265 should have to change intro!! to intro? only); replaced "delrule" by
   266 "rule del";
   267 
   268 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   269 
   270 * Provers: strengthened force_tac by using new first_best_tac;
   271 
   272 * LaTeX document preparation: several changes of isabelle.sty (see
   273 lib/texinputs);
   274 
   275 
   276 *** Document preparation ***
   277 
   278 * formal comments (text blocks etc.) in new-style theories may now
   279 contain antiquotations of thm/prop/term/typ/text to be presented
   280 according to latex print mode; concrete syntax is like this:
   281 @{term[show_types] "f(x) = a + x"};
   282 
   283 * isatool mkdir provides easy setup of Isabelle session directories,
   284 including proper document sources;
   285 
   286 * generated LaTeX sources are now deleted after successful run
   287 (isatool document -c); may retain a copy somewhere else via -D option
   288 of isatool usedir;
   289 
   290 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   291 style files, achieving self-contained LaTeX sources and simplifying
   292 LaTeX debugging;
   293 
   294 * old-style theories now produce (crude) LaTeX output as well;
   295 
   296 * browser info session directories are now self-contained (may be put
   297 on WWW server seperately); improved graphs of nested sessions; removed
   298 graph for 'all sessions';
   299 
   300 * several improvements in isabelle style files; \isabellestyle{it}
   301 produces fake math mode output; \isamarkupheader is now \section by
   302 default; see lib/texinputs/isabelle.sty etc.;
   303 
   304 
   305 *** Isar ***
   306 
   307 * Isar/Pure: local results and corresponding term bindings are now
   308 subject to Hindley-Milner polymorphism (similar to ML); this
   309 accommodates incremental type-inference very nicely;
   310 
   311 * Isar/Pure: new derived language element 'obtain' supports
   312 generalized existence reasoning;
   313 
   314 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   315 support accumulation of results, without applying any rules yet;
   316 useful to collect intermediate results without explicit name
   317 references, and for use with transitivity rules with more than 2
   318 premises;
   319 
   320 * Isar/Pure: scalable support for case-analysis type proofs: new
   321 'case' language element refers to local contexts symbolically, as
   322 produced by certain proof methods; internally, case names are attached
   323 to theorems as "tags";
   324 
   325 * Isar/Pure: theory command 'hide' removes declarations from
   326 class/type/const name spaces;
   327 
   328 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   329 indicate potential overloading;
   330 
   331 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   332 
   333 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   334 "{a,b,c}" instead of {a,b,c};
   335 
   336 * Isar/Pure now provides its own version of intro/elim/dest
   337 attributes; useful for building new logics, but beware of confusion
   338 with the version in Provers/classical;
   339 
   340 * Isar/Pure: the local context of (non-atomic) goals is provided via
   341 case name 'antecedent';
   342 
   343 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   344 to the current context is now done automatically);
   345 
   346 * Isar/Pure: theory command 'method_setup' provides a simple interface
   347 for definining proof methods in ML;
   348 
   349 * Isar/Provers: intro/elim/dest attributes changed; renamed
   350 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   351 most cases, one should have to change intro!! to intro? only);
   352 replaced "delrule" by "rule del";
   353 
   354 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   355 'symmetric' attribute (the latter supercedes [RS sym]);
   356 
   357 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   358 method modifier); 'simp' method: 'only:' modifier removes loopers as
   359 well (including splits);
   360 
   361 * Isar/Provers: Simplifier and Classical methods now support all kind
   362 of modifiers used in the past, including 'cong', 'iff', etc.
   363 
   364 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   365 of Simplifier and Classical reasoner);
   366 
   367 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   368 now support named cases; major packages (inductive, datatype, primrec,
   369 recdef) support case names and properly name parameters;
   370 
   371 * Isar/HOL: new transitivity rules for substitution in inequalities --
   372 monotonicity conditions are extracted to be proven at end of
   373 calculations;
   374 
   375 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   376 method anyway;
   377 
   378 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   379 split_if split_if_asm; datatype package provides theorems foo.splits =
   380 foo.split foo.split_asm for each datatype;
   381 
   382 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   383 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   384 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   385 use "(cases (simplified))" method in proper proof texts);
   386 
   387 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   388 
   389 * Isar: names of theorems etc. may be natural numbers as well;
   390 
   391 * Isar: 'pr' command: optional arguments for goals_limit and
   392 ProofContext.prems_limit; no longer prints theory contexts, but only
   393 proof states;
   394 
   395 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   396 additional print modes to be specified; e.g. "pr(latex)" will print
   397 proof state according to the Isabelle LaTeX style;
   398 
   399 * Isar: improved support for emulating tactic scripts, including proof
   400 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   401 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   402 (for HOL datatypes);
   403 
   404 * Isar: simplified (more robust) goal selection of proof methods: 1st
   405 goal, all goals, or explicit goal specifier (tactic emulation); thus
   406 'proof method scripts' have to be in depth-first order;
   407 
   408 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   409 
   410 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   411 should instead use individual commands for printing items
   412 (print_commands, print_methods etc.);
   413 
   414 * Isar: added 'nothing' --- the empty list of theorems;
   415 
   416 
   417 *** HOL ***
   418 
   419 * HOL/MicroJava: formalization of a fragment of Java, together with a
   420 corresponding virtual machine and a specification of its bytecode
   421 verifier and a lightweight bytecode verifier, including proofs of
   422 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   423 Cornelia Pusch (see also the homepage of project Bali at
   424 http://isabelle.in.tum.de/Bali/);
   425 
   426 * HOL/Algebra: new theory of rings and univariate polynomials, by
   427 Clemens Ballarin;
   428 
   429 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   430 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   431 Rasmussen;
   432 
   433 * HOL/Lattice: fundamental concepts of lattice theory and order
   434 structures, including duals, properties of bounds versus algebraic
   435 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   436 Theorem for complete lattices etc.; may also serve as a demonstration
   437 for abstract algebraic reasoning using axiomatic type classes, and
   438 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   439 
   440 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   441 von Oheimb;
   442 
   443 * HOL/IMPP: extension of IMP with local variables and mutually
   444 recursive procedures, by David von Oheimb;
   445 
   446 * HOL/Lambda: converted into new-style theory and document;
   447 
   448 * HOL/ex/Multiquote: example of multiple nested quotations and
   449 anti-quotations -- basically a generalized version of de-Bruijn
   450 representation; very useful in avoiding lifting of operations;
   451 
   452 * HOL/record: added general record equality rule to simpset; fixed
   453 select-update simplification procedure to handle extended records as
   454 well; admit "r" as field name;
   455 
   456 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   457 other numeric types and also as the identity of groups, rings, etc.;
   458 
   459 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   460 Types nat and int belong to this axclass;
   461 
   462 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   463    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   464    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   465   two terms #m*u and #n*u are replaced by #(m+n)*u
   466     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   467   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   468     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   469 
   470 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   471 powerful prover for predicate logic but knows nothing of clasets; see
   472 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   473 
   474 * HOL: new version of "case_tac" subsumes both boolean case split and
   475 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   476 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   477 
   478 * HOL: simplification no longer dives into case-expressions: only the
   479 selector expression is simplified, but not the remaining arms; to
   480 enable full simplification of case-expressions for datatype t, you may
   481 remove t.weak_case_cong from the simpset, either globally (Delcongs
   482 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   483 
   484 * HOL/recdef: the recursion equations generated by 'recdef' for
   485 function 'f' are now called f.simps instead of f.rules; if all
   486 termination conditions are proved automatically, these simplification
   487 rules are added to the simpset, as in primrec; rules may be named
   488 individually as well, resulting in a separate list of theorems for
   489 each equation;
   490 
   491 * HOL/While is a new theory that provides a while-combinator. It
   492 permits the definition of tail-recursive functions without the
   493 provision of a termination measure. The latter is necessary once the
   494 invariant proof rule for while is applied.
   495 
   496 * HOL: new (overloaded) notation for the set of elements below/above
   497 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   498 
   499 * HOL: theorems impI, allI, ballI bound as "strip";
   500 
   501 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   502 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   503 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   504 
   505 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   506 
   507 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   508 main HOL, but was unused);
   509 
   510 * HOL: fewer consts declared as global (e.g. have to refer to
   511 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   512 
   513 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   514 in case of overlap with user translations (e.g. judgements over
   515 tuples); (note that the underlying logical represenation is still
   516 bogus);
   517 
   518 
   519 *** ZF ***
   520 
   521 * ZF: simplification automatically cancels common terms in arithmetic
   522 expressions over nat and int;
   523 
   524 * ZF: new treatment of nat to minimize type-checking: all operators
   525 coerce their operands to a natural number using the function natify,
   526 making the algebraic laws unconditional;
   527 
   528 * ZF: as above, for int: operators coerce their operands to an integer
   529 using the function intify;
   530 
   531 * ZF: the integer library now contains many of the usual laws for the
   532 orderings, including $<=, and monotonicity laws for $+ and $*;
   533 
   534 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
   535 simplification;
   536 
   537 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
   538 to the simplifier and classical reasoner simultaneously;
   539 
   540 
   541 *** General ***
   542 
   543 * Provers: blast_tac now handles actual object-logic rules as
   544 assumptions; note that auto_tac uses blast_tac internally as well;
   545 
   546 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
   547 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
   548 
   549 * Provers: delrules now handles destruct rules as well (no longer need
   550 explicit make_elim);
   551 
   552 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
   553   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   554 use instead the strong form,
   555   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   556 in HOL, FOL and ZF the function cla_make_elim will create such rules
   557 from destruct-rules;
   558 
   559 * Provers: Simplifier.easy_setup provides a fast path to basic
   560 Simplifier setup for new object-logics;
   561 
   562 * Pure: AST translation rules no longer require constant head on LHS;
   563 
   564 * Pure: improved name spaces: ambiguous output is qualified; support
   565 for hiding of names;
   566 
   567 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
   568 XSYMBOL_HOME; no longer need to do manual configuration in most
   569 situations;
   570 
   571 * system: compression of ML heaps images may now be controlled via -c
   572 option of isabelle and isatool usedir (currently only observed by
   573 Poly/ML);
   574 
   575 * system: isatool installfonts may handle X-Symbol fonts as well (very
   576 useful for remote X11);
   577 
   578 * system: provide TAGS file for Isabelle sources;
   579 
   580 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
   581 order;
   582 
   583 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
   584 timing flag supersedes proof_timing and Toplevel.trace;
   585 
   586 * ML: new combinators |>> and |>>> for incremental transformations
   587 with secondary results (e.g. certain theory extensions):
   588 
   589 * ML: PureThy.add_defs gets additional argument to indicate potential
   590 overloading (usually false);
   591 
   592 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
   593 results;
   594 
   595 
   596 
   597 New in Isabelle99 (October 1999)
   598 --------------------------------
   599 
   600 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   601 
   602 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
   603 are no longer simplified.  (This allows the simplifier to unfold recursive
   604 functional programs.)  To restore the old behaviour, declare
   605 
   606     Delcongs [if_weak_cong];
   607 
   608 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
   609 complement;
   610 
   611 * HOL: the predicate "inj" is now defined by translation to "inj_on";
   612 
   613 * HOL/datatype: mutual_induct_tac no longer exists --
   614   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
   615 
   616 * HOL/typedef: fixed type inference for representing set; type
   617 arguments now have to occur explicitly on the rhs as type constraints;
   618 
   619 * ZF: The con_defs part of an inductive definition may no longer refer
   620 to constants declared in the same theory;
   621 
   622 * HOL, ZF: the function mk_cases, generated by the inductive
   623 definition package, has lost an argument.  To simplify its result, it
   624 uses the default simpset instead of a supplied list of theorems.
   625 
   626 * HOL/List: the constructors of type list are now Nil and Cons;
   627 
   628 * Simplifier: the type of the infix ML functions
   629         setSSolver addSSolver setSolver addSolver
   630 is now  simpset * solver -> simpset  where `solver' is a new abstract type
   631 for packaging solvers. A solver is created via
   632         mk_solver: string -> (thm list -> int -> tactic) -> solver
   633 where the string argument is only a comment.
   634 
   635 
   636 *** Proof tools ***
   637 
   638 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
   639 decision procedure for linear arithmetic. Currently it is used for
   640 types `nat', `int', and `real' in HOL (see below); it can, should and
   641 will be instantiated for other types and logics as well.
   642 
   643 * The simplifier now accepts rewrite rules with flexible heads, eg
   644      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
   645   They are applied like any rule with a non-pattern lhs, i.e. by first-order
   646   matching.
   647 
   648 
   649 *** General ***
   650 
   651 * New Isabelle/Isar subsystem provides an alternative to traditional
   652 tactical theorem proving; together with the ProofGeneral/isar user
   653 interface it offers an interactive environment for developing human
   654 readable proof documents (Isar == Intelligible semi-automated
   655 reasoning); for further information see isatool doc isar-ref,
   656 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
   657 
   658 * improved and simplified presentation of theories: better HTML markup
   659 (including colors), graph views in several sizes; isatool usedir now
   660 provides a proper interface for user theories (via -P option); actual
   661 document preparation based on (PDF)LaTeX is available as well (for
   662 new-style theories only); see isatool doc system for more information;
   663 
   664 * native support for Proof General, both for classic Isabelle and
   665 Isabelle/Isar;
   666 
   667 * ML function thm_deps visualizes dependencies of theorems and lemmas,
   668 using the graph browser tool;
   669 
   670 * Isabelle manuals now also available as PDF;
   671 
   672 * theory loader rewritten from scratch (may not be fully
   673 bug-compatible); old loadpath variable has been replaced by show_path,
   674 add_path, del_path, reset_path functions; new operations such as
   675 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
   676 isatool doc ref);
   677 
   678 * improved isatool install: option -k creates KDE application icon,
   679 option -p DIR installs standalone binaries;
   680 
   681 * added ML_PLATFORM setting (useful for cross-platform installations);
   682 more robust handling of platform specific ML images for SML/NJ;
   683 
   684 * the settings environment is now statically scoped, i.e. it is never
   685 created again in sub-processes invoked from isabelle, isatool, or
   686 Isabelle;
   687 
   688 * path element specification '~~' refers to '$ISABELLE_HOME';
   689 
   690 * in locales, the "assumes" and "defines" parts may be omitted if
   691 empty;
   692 
   693 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   694 long arrows);
   695 
   696 * new print_mode "HTML";
   697 
   698 * new flag show_tags controls display of tags of theorems (which are
   699 basically just comments that may be attached by some tools);
   700 
   701 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   702 mode and goal output format:
   703 
   704 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   705 244c244
   706 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   707 ---
   708 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   709 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   710 181c181
   711 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   712 ---
   713 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   714 
   715 * function bind_thms stores lists of theorems (cf. bind_thm);
   716 
   717 * new shorthand tactics ftac, eatac, datac, fatac;
   718 
   719 * qed (and friends) now accept "" as result name; in that case the
   720 theorem is not stored, but proper checks and presentation of the
   721 result still apply;
   722 
   723 * theorem database now also indexes constants "Trueprop", "all",
   724 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   725 
   726 
   727 *** HOL ***
   728 
   729 ** HOL arithmetic **
   730 
   731 * There are now decision procedures for linear arithmetic over nat and
   732 int:
   733 
   734 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   735 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   736 are treated as atomic; subformulae not involving type `nat' or `int'
   737 are ignored; quantified subformulae are ignored unless they are
   738 positive universal or negative existential. The tactic has to be
   739 invoked by hand and can be a little bit slow. In particular, the
   740 running time is exponential in the number of occurrences of `min' and
   741 `max', and `-' on `nat'.
   742 
   743 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   744 (negated) (in)equalities among the premises and the conclusion into
   745 account (i.e. no compound formulae) and does not know about `min' and
   746 `max', and `-' on `nat'. It is fast and is used automatically by the
   747 simplifier.
   748 
   749 NB: At the moment, these decision procedures do not cope with mixed
   750 nat/int formulae where the two parts interact, such as `m < n ==>
   751 int(m) < int(n)'.
   752 
   753 * HOL/Numeral provides a generic theory of numerals (encoded
   754 efficiently as bit strings); setup for types nat/int/real is in place;
   755 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   756 int, existing theories and proof scripts may require a few additional
   757 type constraints;
   758 
   759 * integer division and remainder can now be performed on constant
   760 arguments;
   761 
   762 * many properties of integer multiplication, division and remainder
   763 are now available;
   764 
   765 * An interface to the Stanford Validity Checker (SVC) is available through the
   766 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   767 are proved automatically.  SVC must be installed separately, and its results
   768 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   769 invocation of the underlying oracle).  For SVC see
   770   http://verify.stanford.edu/SVC
   771 
   772 * IsaMakefile: the HOL-Real target now builds an actual image;
   773 
   774 
   775 ** HOL misc **
   776 
   777 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   778 (in Isabelle/Isar) -- by Gertrud Bauer;
   779 
   780 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   781 analysis for assembly languages with subtypes;
   782 
   783 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   784 -- avoids syntactic ambiguities and treats state, transition, and
   785 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   786 changed syntax and (many) tactics;
   787 
   788 * HOL/inductive: Now also handles more general introduction rules such
   789   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
   790   theorems are now maintained within the theory (maintained via the
   791   "mono" attribute);
   792 
   793 * HOL/datatype: Now also handles arbitrarily branching datatypes
   794   (using function types) such as
   795 
   796   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
   797 
   798 * HOL/record: record_simproc (part of the default simpset) takes care
   799 of selectors applied to updated records; record_split_tac is no longer
   800 part of the default claset; update_defs may now be removed from the
   801 simpset in many cases; COMPATIBILITY: old behavior achieved by
   802 
   803   claset_ref () := claset() addSWrapper record_split_wrapper;
   804   Delsimprocs [record_simproc]
   805 
   806 * HOL/typedef: fixed type inference for representing set; type
   807 arguments now have to occur explicitly on the rhs as type constraints;
   808 
   809 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
   810 names rather than an ML expression;
   811 
   812 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
   813 supplied later.  Program schemes can be defined, such as
   814     "While B C s = (if B s then While B C (C s) else s)"
   815 where the well-founded relation can be chosen after B and C have been given.
   816 
   817 * HOL/List: the constructors of type list are now Nil and Cons;
   818 INCOMPATIBILITY: while [] and infix # syntax is still there, of
   819 course, ML tools referring to List.list.op # etc. have to be adapted;
   820 
   821 * HOL_quantifiers flag superseded by "HOL" print mode, which is
   822 disabled by default; run isabelle with option -m HOL to get back to
   823 the original Gordon/HOL-style output;
   824 
   825 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
   826 ALL x<=y. P, EX x<y. P, EX x<=y. P;
   827 
   828 * HOL basic syntax simplified (more orthogonal): all variants of
   829 All/Ex now support plain / symbolic / HOL notation; plain syntax for
   830 Eps operator is provided as well: "SOME x. P[x]";
   831 
   832 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
   833 
   834 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
   835 thus available for user theories;
   836 
   837 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
   838 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
   839 time;
   840 
   841 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
   842 several times and then mp;
   843 
   844 
   845 *** LK ***
   846 
   847 * the notation <<...>> is now available as a notation for sequences of
   848 formulas;
   849 
   850 * the simplifier is now installed
   851 
   852 * the axiom system has been generalized (thanks to Soren Heilmann)
   853 
   854 * the classical reasoner now has a default rule database
   855 
   856 
   857 *** ZF ***
   858 
   859 * new primrec section allows primitive recursive functions to be given
   860 directly (as in HOL) over datatypes and the natural numbers;
   861 
   862 * new tactics induct_tac and exhaust_tac for induction (or case
   863 analysis) over datatypes and the natural numbers;
   864 
   865 * the datatype declaration of type T now defines the recursor T_rec;
   866 
   867 * simplification automatically does freeness reasoning for datatype
   868 constructors;
   869 
   870 * automatic type-inference, with AddTCs command to insert new
   871 type-checking rules;
   872 
   873 * datatype introduction rules are now added as Safe Introduction rules
   874 to the claset;
   875 
   876 * the syntax "if P then x else y" is now available in addition to
   877 if(P,x,y);
   878 
   879 
   880 *** Internal programming interfaces ***
   881 
   882 * tuned simplifier trace output; new flag debug_simp;
   883 
   884 * structures Vartab / Termtab (instances of TableFun) offer efficient
   885 tables indexed by indexname_ord / term_ord (compatible with aconv);
   886 
   887 * AxClass.axclass_tac lost the theory argument;
   888 
   889 * tuned current_goals_markers semantics: begin / end goal avoids
   890 printing empty lines;
   891 
   892 * removed prs and prs_fn hook, which was broken because it did not
   893 include \n in its semantics, forcing writeln to add one
   894 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
   895 string -> unit if you really want to output text without newline;
   896 
   897 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
   898 plain output, interface builders may have to enable 'isabelle_font'
   899 mode to get Isabelle font glyphs as before;
   900 
   901 * refined token_translation interface; INCOMPATIBILITY: output length
   902 now of type real instead of int;
   903 
   904 * theory loader actions may be traced via new ThyInfo.add_hook
   905 interface (see src/Pure/Thy/thy_info.ML); example application: keep
   906 your own database of information attached to *whole* theories -- as
   907 opposed to intra-theory data slots offered via TheoryDataFun;
   908 
   909 * proper handling of dangling sort hypotheses (at last!);
   910 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
   911 extra sort hypotheses that can be witnessed from the type signature;
   912 the force_strip_shyps flag is gone, any remaining shyps are simply
   913 left in the theorem (with a warning issued by strip_shyps_warning);
   914 
   915 
   916 
   917 New in Isabelle98-1 (October 1998)
   918 ----------------------------------
   919 
   920 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   921 
   922 * several changes of automated proof tools;
   923 
   924 * HOL: major changes to the inductive and datatype packages, including
   925 some minor incompatibilities of theory syntax;
   926 
   927 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
   928 called `inj_on';
   929 
   930 * HOL: removed duplicate thms in Arith:
   931   less_imp_add_less  should be replaced by  trans_less_add1
   932   le_imp_add_le      should be replaced by  trans_le_add1
   933 
   934 * HOL: unary minus is now overloaded (new type constraints may be
   935 required);
   936 
   937 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
   938 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
   939 now taken as an integer constant.
   940 
   941 * Pure: ML function 'theory_of' renamed to 'theory';
   942 
   943 
   944 *** Proof tools ***
   945 
   946 * Simplifier:
   947   1. Asm_full_simp_tac is now more aggressive.
   948      1. It will sometimes reorient premises if that increases their power to
   949         simplify.
   950      2. It does no longer proceed strictly from left to right but may also
   951         rotate premises to achieve further simplification.
   952      For compatibility reasons there is now Asm_lr_simp_tac which is like the
   953      old Asm_full_simp_tac in that it does not rotate premises.
   954   2. The simplifier now knows a little bit about nat-arithmetic.
   955 
   956 * Classical reasoner: wrapper mechanism for the classical reasoner now
   957 allows for selected deletion of wrappers, by introduction of names for
   958 wrapper functionals.  This implies that addbefore, addSbefore,
   959 addaltern, and addSaltern now take a pair (name, tactic) as argument,
   960 and that adding two tactics with the same name overwrites the first
   961 one (emitting a warning).
   962   type wrapper = (int -> tactic) -> (int -> tactic)
   963   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
   964   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
   965   delWrapper, delSWrapper: claset *  string            -> claset
   966   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
   967 
   968 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
   969 semantics; addbefore now affects only the unsafe part of step_tac
   970 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
   971 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
   972 by Force_tac;
   973 
   974 * Classical reasoner: setwrapper to setWrapper and compwrapper to
   975 compWrapper; added safe wrapper (and access functions for it);
   976 
   977 * HOL/split_all_tac is now much faster and fails if there is nothing
   978 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
   979 and the names of the automatically generated variables have changed.
   980 split_all_tac has moved within claset() from unsafe wrappers to safe
   981 wrappers, which means that !!-bound variables are split much more
   982 aggressively, and safe_tac and clarify_tac now split such variables.
   983 If this splitting is not appropriate, use delSWrapper "split_all_tac".
   984 Note: the same holds for record_split_tac, which does the job of
   985 split_all_tac for record fields.
   986 
   987 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
   988 permanently to the default simpset using Addsplits just like
   989 Addsimps. They can be removed via Delsplits just like
   990 Delsimps. Lower-case versions are also available.
   991 
   992 * HOL/Simplifier: The rule split_if is now part of the default
   993 simpset. This means that the simplifier will eliminate all occurrences
   994 of if-then-else in the conclusion of a goal. To prevent this, you can
   995 either remove split_if completely from the default simpset by
   996 `Delsplits [split_if]' or remove it in a specific call of the
   997 simplifier using `... delsplits [split_if]'.  You can also add/delete
   998 other case splitting rules to/from the default simpset: every datatype
   999 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1000 t is the name of the datatype).
  1001 
  1002 * Classical reasoner / Simplifier combination: new force_tac (and
  1003 derivatives Force_tac, force) combines rewriting and classical
  1004 reasoning (and whatever other tools) similarly to auto_tac, but is
  1005 aimed to solve the given subgoal completely.
  1006 
  1007 
  1008 *** General ***
  1009 
  1010 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1011 and `goalw': the theory is no longer needed as an explicit argument -
  1012 the current theory context is used; assumptions are no longer returned
  1013 at the ML-level unless one of them starts with ==> or !!; it is
  1014 recommended to convert to these new commands using isatool fixgoal
  1015 (backup your sources first!);
  1016 
  1017 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1018 the current theory context, and 'theory' to lookup stored theories;
  1019 
  1020 * new theory section 'locale' for declaring constants, assumptions and
  1021 definitions that have local scope;
  1022 
  1023 * new theory section 'nonterminals' for purely syntactic types;
  1024 
  1025 * new theory section 'setup' for generic ML setup functions
  1026 (e.g. package initialization);
  1027 
  1028 * the distribution now includes Isabelle icons: see
  1029 lib/logo/isabelle-{small,tiny}.xpm;
  1030 
  1031 * isatool install - install binaries with absolute references to
  1032 ISABELLE_HOME/bin;
  1033 
  1034 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1035 
  1036 * print mode 'emacs' reserved for Isamode;
  1037 
  1038 * support multiple print (ast) translations per constant name;
  1039 
  1040 * theorems involving oracles are now printed with a suffixed [!];
  1041 
  1042 
  1043 *** HOL ***
  1044 
  1045 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1046 
  1047 * HOL/inductive package reorganized and improved: now supports mutual
  1048 definitions such as
  1049 
  1050   inductive EVEN ODD
  1051     intrs
  1052       null "0 : EVEN"
  1053       oddI "n : EVEN ==> Suc n : ODD"
  1054       evenI "n : ODD ==> Suc n : EVEN"
  1055 
  1056 new theorem list "elims" contains an elimination rule for each of the
  1057 recursive sets; inductive definitions now handle disjunctive premises
  1058 correctly (also ZF);
  1059 
  1060 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1061 "mutual_induct" no longer exists - the induction rule is always
  1062 contained in "induct";
  1063 
  1064 
  1065 * HOL/datatype package re-implemented and greatly improved: now
  1066 supports mutually recursive datatypes such as
  1067 
  1068   datatype
  1069     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1070             | SUM ('a aexp) ('a aexp)
  1071             | DIFF ('a aexp) ('a aexp)
  1072             | NUM 'a
  1073   and
  1074     'a bexp = LESS ('a aexp) ('a aexp)
  1075             | AND ('a bexp) ('a bexp)
  1076             | OR ('a bexp) ('a bexp)
  1077 
  1078 as well as indirectly recursive datatypes such as
  1079 
  1080   datatype
  1081     ('a, 'b) term = Var 'a
  1082                   | App 'b ((('a, 'b) term) list)
  1083 
  1084 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1085 induction on mutually / indirectly recursive datatypes.
  1086 
  1087 Primrec equations are now stored in theory and can be accessed via
  1088 <function_name>.simps.
  1089 
  1090 INCOMPATIBILITIES:
  1091 
  1092   - Theories using datatypes must now have theory Datatype as an
  1093     ancestor.
  1094   - The specific <typename>.induct_tac no longer exists - use the
  1095     generic induct_tac instead.
  1096   - natE has been renamed to nat.exhaust - use exhaust_tac
  1097     instead of res_inst_tac ... natE. Note that the variable
  1098     names in nat.exhaust differ from the names in natE, this
  1099     may cause some "fragile" proofs to fail.
  1100   - The theorems split_<typename>_case and split_<typename>_case_asm
  1101     have been renamed to <typename>.split and <typename>.split_asm.
  1102   - Since default sorts of type variables are now handled correctly,
  1103     some datatype definitions may have to be annotated with explicit
  1104     sort constraints.
  1105   - Primrec definitions no longer require function name and type
  1106     of recursive argument.
  1107 
  1108 Consider using isatool fixdatatype to adapt your theories and proof
  1109 scripts to the new package (backup your sources first!).
  1110 
  1111 
  1112 * HOL/record package: considerably improved implementation; now
  1113 includes concrete syntax for record types, terms, updates; theorems
  1114 for surjective pairing and splitting !!-bound record variables; proof
  1115 support is as follows:
  1116 
  1117   1) standard conversions (selectors or updates applied to record
  1118 constructor terms) are part of the standard simpset;
  1119 
  1120   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1121 made part of standard simpset and claset via addIffs;
  1122 
  1123   3) a tactic for record field splitting (record_split_tac) is part of
  1124 the standard claset (addSWrapper);
  1125 
  1126 To get a better idea about these rules you may retrieve them via
  1127 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1128 the name of your record type.
  1129 
  1130 The split tactic 3) conceptually simplifies by the following rule:
  1131 
  1132   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1133 
  1134 Thus any record variable that is bound by meta-all will automatically
  1135 blow up into some record constructor term, consequently the
  1136 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1137 solve record problems automatically.
  1138 
  1139 
  1140 * reorganized the main HOL image: HOL/Integ and String loaded by
  1141 default; theory Main includes everything;
  1142 
  1143 * automatic simplification of integer sums and comparisons, using cancellation;
  1144 
  1145 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1146 
  1147 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1148 
  1149 * many new identities for unions, intersections, set difference, etc.;
  1150 
  1151 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1152 called split_if, split_split, split_sum_case and split_nat_case (to go
  1153 with add/delsplits);
  1154 
  1155 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1156 (?x::unit) = (); this is made part of the default simpset, which COULD
  1157 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1158 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1159 unit_abs_eta_conv is added in order to counter the effect of
  1160 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1161 %u.f();
  1162 
  1163 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1164 makes more sense);
  1165 
  1166 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1167   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1168   disjointness reasoning but breaking a few old proofs.
  1169 
  1170 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1171 to 'converse' from 'inverse' (for compatibility with ZF and some
  1172 literature);
  1173 
  1174 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1175 the well-founded relation;
  1176 
  1177 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1178     Compl A.  The "Compl" syntax remains available as input syntax for this
  1179     release ONLY.
  1180 
  1181 * HOL/Update: new theory of function updates:
  1182     f(a:=b) == %x. if x=a then b else f x
  1183 may also be iterated as in f(a:=b,c:=d,...);
  1184 
  1185 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1186 
  1187 * HOL/List:
  1188   - new function list_update written xs[i:=v] that updates the i-th
  1189     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1190   - new function `upt' written [i..j(] which generates the list
  1191     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1192     bound write [i..j], which is a shorthand for [i..j+1(].
  1193   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1194 
  1195 * HOL/Arith:
  1196   - removed 'pred' (predecessor) function;
  1197   - generalized some theorems about n-1;
  1198   - many new laws about "div" and "mod";
  1199   - new laws about greatest common divisors (see theory ex/Primes);
  1200 
  1201 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1202 instead of "inverse";
  1203 
  1204 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1205   of the multiset ordering;
  1206 
  1207 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1208   (not included by default);
  1209 
  1210 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1211 
  1212 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1213   programs, i.e. different program variables may have different types.
  1214 
  1215 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1216   [previously, this check worked only if the rewrite rule was unconditional]
  1217   Now rew can involve either definitions or equalities (either == or =).
  1218 
  1219 
  1220 *** ZF ***
  1221 
  1222 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1223   only the theorems proved on ZF.ML;
  1224 
  1225 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1226   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1227   disjointness reasoning but breaking a few old proofs.
  1228 
  1229 * ZF/Update: new theory of function updates
  1230     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1231   may also be iterated as in f(a:=b,c:=d,...);
  1232 
  1233 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1234 
  1235 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1236   [previously, this check worked only if the rewrite rule was unconditional]
  1237   Now rew can involve either definitions or equalities (either == or =).
  1238 
  1239 * case_tac provided for compatibility with HOL
  1240     (like the old excluded_middle_tac, but with subgoals swapped)
  1241 
  1242 
  1243 *** Internal programming interfaces ***
  1244 
  1245 * Pure: several new basic modules made available for general use, see
  1246 also src/Pure/README;
  1247 
  1248 * improved the theory data mechanism to support encapsulation (data
  1249 kind name replaced by private Object.kind, acting as authorization
  1250 key); new type-safe user interface via functor TheoryDataFun; generic
  1251 print_data function becomes basically useless;
  1252 
  1253 * removed global_names compatibility flag -- all theory declarations
  1254 are qualified by default;
  1255 
  1256 * module Pure/Syntax now offers quote / antiquote translation
  1257 functions (useful for Hoare logic etc. with implicit dependencies);
  1258 see HOL/ex/Antiquote for an example use;
  1259 
  1260 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1261 cterm -> thm;
  1262 
  1263 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1264 subgoal;
  1265 
  1266 * Display.print_goals function moved to Locale.print_goals;
  1267 
  1268 * standard print function for goals supports current_goals_markers
  1269 variable for marking begin of proof, end of proof, start of goal; the
  1270 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1271 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1272 for example;
  1273 
  1274 
  1275 
  1276 New in Isabelle98 (January 1998)
  1277 --------------------------------
  1278 
  1279 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1280 
  1281 * changed lexical syntax of terms / types: dots made part of long
  1282 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1283 
  1284 * simpset (and claset) reference variable replaced by functions
  1285 simpset / simpset_ref;
  1286 
  1287 * no longer supports theory aliases (via merge) and non-trivial
  1288 implicit merge of thms' signatures;
  1289 
  1290 * most internal names of constants changed due to qualified names;
  1291 
  1292 * changed Pure/Sequence interface (see Pure/seq.ML);
  1293 
  1294 
  1295 *** General Changes ***
  1296 
  1297 * hierachically structured name spaces (for consts, types, axms, thms
  1298 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1299 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1300 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1301 long_names for fully qualified output names; NOTE: ML programs
  1302 (special tactics, packages etc.) referring to internal names may have
  1303 to be adapted to cope with fully qualified names; in case of severe
  1304 backward campatibility problems try setting 'global_names' at compile
  1305 time to have enrything declared within a flat name space; one may also
  1306 fine tune name declarations in theories via the 'global' and 'local'
  1307 section;
  1308 
  1309 * reimplemented the implicit simpset and claset using the new anytype
  1310 data filed in signatures; references simpset:simpset ref etc. are
  1311 replaced by functions simpset:unit->simpset and
  1312 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1313 to patch your ML files accordingly;
  1314 
  1315 * HTML output now includes theory graph data for display with Java
  1316 applet or isatool browser; data generated automatically via isatool
  1317 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1318 
  1319 * defs may now be conditional; improved rewrite_goals_tac to handle
  1320 conditional equations;
  1321 
  1322 * defs now admits additional type arguments, using TYPE('a) syntax;
  1323 
  1324 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1325 creates a new theory node; implicit merge of thms' signatures is
  1326 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1327 transfer:theory->thm->thm in (rare) cases;
  1328 
  1329 * improved handling of draft signatures / theories; draft thms (and
  1330 ctyps, cterms) are automatically promoted to real ones;
  1331 
  1332 * slightly changed interfaces for oracles: admit many per theory, named
  1333 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1334 
  1335 * print_goals: optional output of const types (set show_consts and
  1336 show_types);
  1337 
  1338 * improved output of warnings (###) and errors (***);
  1339 
  1340 * subgoal_tac displays a warning if the new subgoal has type variables;
  1341 
  1342 * removed old README and Makefiles;
  1343 
  1344 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1345 
  1346 * removed obsolete init_pps and init_database;
  1347 
  1348 * deleted the obsolete tactical STATE, which was declared by
  1349     fun STATE tacfun st = tacfun st st;
  1350 
  1351 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1352 (which abbreviates $HOME);
  1353 
  1354 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1355 use isatool fixseq to adapt your ML programs (this works for fully
  1356 qualified references to the Sequence structure only!);
  1357 
  1358 * use_thy no longer requires writable current directory; it always
  1359 reloads .ML *and* .thy file, if either one is out of date;
  1360 
  1361 
  1362 *** Classical Reasoner ***
  1363 
  1364 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1365 tactics that use classical reasoning to simplify a subgoal without
  1366 splitting it into several subgoals;
  1367 
  1368 * Safe_tac: like safe_tac but uses the default claset;
  1369 
  1370 
  1371 *** Simplifier ***
  1372 
  1373 * added simplification meta rules:
  1374     (asm_)(full_)simplify: simpset -> thm -> thm;
  1375 
  1376 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1377 logics (again);
  1378 
  1379 * added prems argument to simplification procedures;
  1380 
  1381 * HOL, FOL, ZF: added infix function `addsplits':
  1382   instead of `<simpset> setloop (split_tac <thms>)'
  1383   you can simply write `<simpset> addsplits <thms>'
  1384 
  1385 
  1386 *** Syntax ***
  1387 
  1388 * TYPE('a) syntax for type reflection terms;
  1389 
  1390 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1391 
  1392 * pretty printer: changed order of mixfix annotation preference (again!);
  1393 
  1394 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1395 
  1396 
  1397 *** HOL ***
  1398 
  1399 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1400   with `addloop' of the simplifier to faciliate case splitting in premises.
  1401 
  1402 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1403 
  1404 * HOL/Auth: new protocol proofs including some for the Internet
  1405   protocol TLS;
  1406 
  1407 * HOL/Map: new theory of `maps' a la VDM;
  1408 
  1409 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1410 cancelling out common nat summands from =, <, <= (in)equalities, or
  1411 differences; simplification procedures nat_cancel_factor for
  1412 cancelling common factor from =, <, <= (in)equalities over natural
  1413 sums; nat_cancel contains both kinds of procedures, it is installed by
  1414 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1415 
  1416 * HOL/simplifier: terms of the form
  1417   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1418   are rewritten to
  1419   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1420   and those of the form
  1421   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1422   are rewritten to
  1423   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1424 
  1425 * HOL/datatype
  1426   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1427 
  1428   P(t_case f1 ... fn x) =
  1429      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1430         ...
  1431        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1432      )
  1433 
  1434   and a theorem `split_t_case_asm' of the form
  1435 
  1436   P(t_case f1 ... fn x) =
  1437     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1438         ...
  1439        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1440      )
  1441   which can be added to a simpset via `addsplits'. The existing theorems
  1442   expand_list_case and expand_option_case have been renamed to
  1443   split_list_case and split_option_case.
  1444 
  1445 * HOL/Arithmetic:
  1446   - `pred n' is automatically converted to `n-1'.
  1447     Users are strongly encouraged not to use `pred' any longer,
  1448     because it will disappear altogether at some point.
  1449   - Users are strongly encouraged to write "0 < n" rather than
  1450     "n ~= 0". Theorems and proof tools have been modified towards this
  1451     `standard'.
  1452 
  1453 * HOL/Lists:
  1454   the function "set_of_list" has been renamed "set" (and its theorems too);
  1455   the function "nth" now takes its arguments in the reverse order and
  1456   has acquired the infix notation "!" as in "xs!n".
  1457 
  1458 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1459 
  1460 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1461   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1462 
  1463 * HOL/record: extensible records with schematic structural subtyping
  1464 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1465 still lacks various theorems and concrete record syntax;
  1466 
  1467 
  1468 *** HOLCF ***
  1469 
  1470 * removed "axioms" and "generated by" sections;
  1471 
  1472 * replaced "ops" section by extended "consts" section, which is capable of
  1473   handling the continuous function space "->" directly;
  1474 
  1475 * domain package:
  1476   . proves theorems immediately and stores them in the theory,
  1477   . creates hierachical name space,
  1478   . now uses normal mixfix annotations (instead of cinfix...),
  1479   . minor changes to some names and values (for consistency),
  1480   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1481   . separator between mutual domain defs: changed "," to "and",
  1482   . improved handling of sort constraints;  now they have to
  1483     appear on the left-hand side of the equations only;
  1484 
  1485 * fixed LAM <x,y,zs>.b syntax;
  1486 
  1487 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1488 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1489 
  1490 
  1491 *** FOL and ZF ***
  1492 
  1493 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1494   with `addloop' of the simplifier to faciliate case splitting in premises.
  1495 
  1496 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1497 in HOL, they strip ALL and --> from proved theorems;
  1498 
  1499 
  1500 
  1501 New in Isabelle94-8 (May 1997)
  1502 ------------------------------
  1503 
  1504 *** General Changes ***
  1505 
  1506 * new utilities to build / run / maintain Isabelle etc. (in parts
  1507 still somewhat experimental); old Makefiles etc. still functional;
  1508 
  1509 * new 'Isabelle System Manual';
  1510 
  1511 * INSTALL text, together with ./configure and ./build scripts;
  1512 
  1513 * reimplemented type inference for greater efficiency, better error
  1514 messages and clean internal interface;
  1515 
  1516 * prlim command for dealing with lots of subgoals (an easier way of
  1517 setting goals_limit);
  1518 
  1519 
  1520 *** Syntax ***
  1521 
  1522 * supports alternative (named) syntax tables (parser and pretty
  1523 printer); internal interface is provided by add_modesyntax(_i);
  1524 
  1525 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1526 be used in conjunction with the Isabelle symbol font; uses the
  1527 "symbols" syntax table;
  1528 
  1529 * added token_translation interface (may translate name tokens in
  1530 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1531 the current print_mode); IMPORTANT: user print translation functions
  1532 are responsible for marking newly introduced bounds
  1533 (Syntax.mark_boundT);
  1534 
  1535 * token translations for modes "xterm" and "xterm_color" that display
  1536 names in bold, underline etc. or colors (which requires a color
  1537 version of xterm);
  1538 
  1539 * infixes may now be declared with names independent of their syntax;
  1540 
  1541 * added typed_print_translation (like print_translation, but may
  1542 access type of constant);
  1543 
  1544 
  1545 *** Classical Reasoner ***
  1546 
  1547 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  1548 some limitations.  Blast_tac...
  1549   + ignores addss, addbefore, addafter; this restriction is intrinsic
  1550   + ignores elimination rules that don't have the correct format
  1551         (the conclusion MUST be a formula variable)
  1552   + ignores types, which can make HOL proofs fail
  1553   + rules must not require higher-order unification, e.g. apply_type in ZF
  1554     [message "Function Var's argument not a bound variable" relates to this]
  1555   + its proof strategy is more general but can actually be slower
  1556 
  1557 * substitution with equality assumptions no longer permutes other
  1558 assumptions;
  1559 
  1560 * minor changes in semantics of addafter (now called addaltern); renamed
  1561 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  1562 (and access functions for it);
  1563 
  1564 * improved combination of classical reasoner and simplifier:
  1565   + functions for handling clasimpsets
  1566   + improvement of addss: now the simplifier is called _after_ the
  1567     safe steps.
  1568   + safe variant of addss called addSss: uses safe simplifications
  1569     _during_ the safe steps. It is more complete as it allows multiple
  1570     instantiations of unknowns (e.g. with slow_tac).
  1571 
  1572 *** Simplifier ***
  1573 
  1574 * added interface for simplification procedures (functions that
  1575 produce *proven* rewrite rules on the fly, depending on current
  1576 redex);
  1577 
  1578 * ordering on terms as parameter (used for ordered rewriting);
  1579 
  1580 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  1581 
  1582 * the solver is now split into a safe and an unsafe part.
  1583 This should be invisible for the normal user, except that the
  1584 functions setsolver and addsolver have been renamed to setSolver and
  1585 addSolver; added safe_asm_full_simp_tac;
  1586 
  1587 
  1588 *** HOL ***
  1589 
  1590 * a generic induction tactic `induct_tac' which works for all datatypes and
  1591 also for type `nat';
  1592 
  1593 * a generic case distinction tactic `exhaust_tac' which works for all
  1594 datatypes and also for type `nat';
  1595 
  1596 * each datatype comes with a function `size';
  1597 
  1598 * patterns in case expressions allow tuple patterns as arguments to
  1599 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1600 
  1601 * primrec now also works with type nat;
  1602 
  1603 * recdef: a new declaration form, allows general recursive functions to be
  1604 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1605 
  1606 * the constant for negation has been renamed from "not" to "Not" to
  1607 harmonize with FOL, ZF, LK, etc.;
  1608 
  1609 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1610 infinite lists;
  1611 
  1612 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1613 
  1614 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1615 problems in commutative rings, using axiomatic type classes for + and *;
  1616 
  1617 * more examples in HOL/MiniML and HOL/Auth;
  1618 
  1619 * more default rewrite rules for quantifiers, union/intersection;
  1620 
  1621 * a new constant `arbitrary == @x.False';
  1622 
  1623 * HOLCF/IOA replaces old HOL/IOA;
  1624 
  1625 * HOLCF changes: derived all rules and arities
  1626   + axiomatic type classes instead of classes
  1627   + typedef instead of faking type definitions
  1628   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1629   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1630   + eliminated the types void, one, tr
  1631   + use unit lift and bool lift (with translations) instead of one and tr
  1632   + eliminated blift from Lift3.thy (use Def instead of blift)
  1633   all eliminated rules are derived as theorems --> no visible changes ;
  1634 
  1635 
  1636 *** ZF ***
  1637 
  1638 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1639 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1640 as ZF_cs addSIs [equalityI];
  1641 
  1642 
  1643 
  1644 New in Isabelle94-7 (November 96)
  1645 ---------------------------------
  1646 
  1647 * allowing negative levels (as offsets) in prlev and choplev;
  1648 
  1649 * super-linear speedup for large simplifications;
  1650 
  1651 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1652 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1653 FAIL); can suppress it using the command Delsimps (ex_simps @
  1654 all_simps); De Morgan laws are also now included, by default;
  1655 
  1656 * improved printing of ==>  :  ~:
  1657 
  1658 * new object-logic "Sequents" adds linear logic, while replacing LK
  1659 and Modal (thanks to Sara Kalvala);
  1660 
  1661 * HOL/Auth: correctness proofs for authentication protocols;
  1662 
  1663 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1664 examples on HOL/Auth);
  1665 
  1666 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1667 the rewriter and classical reasoner simultaneously;
  1668 
  1669 * function uresult no longer returns theorems in "standard" format;
  1670 regain previous version by: val uresult = standard o uresult;
  1671 
  1672 
  1673 
  1674 New in Isabelle94-6
  1675 -------------------
  1676 
  1677 * oracles -- these establish an interface between Isabelle and trusted
  1678 external reasoners, which may deliver results as theorems;
  1679 
  1680 * proof objects (in particular record all uses of oracles);
  1681 
  1682 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1683 
  1684 * "constdefs" section in theory files;
  1685 
  1686 * "primrec" section (HOL) no longer requires names;
  1687 
  1688 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1689 
  1690 
  1691 
  1692 New in Isabelle94-5
  1693 -------------------
  1694 
  1695 * reduced space requirements;
  1696 
  1697 * automatic HTML generation from theories;
  1698 
  1699 * theory files no longer require "..." (quotes) around most types;
  1700 
  1701 * new examples, including two proofs of the Church-Rosser theorem;
  1702 
  1703 * non-curried (1994) version of HOL is no longer distributed;
  1704 
  1705 
  1706 
  1707 New in Isabelle94-4
  1708 -------------------
  1709 
  1710 * greatly reduced space requirements;
  1711 
  1712 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1713 
  1714 * searchable theorem database (see the section "Retrieving theorems" on
  1715 page 8 of the Reference Manual);
  1716 
  1717 * new examples, including Grabczewski's monumental case study of the
  1718 Axiom of Choice;
  1719 
  1720 * The previous version of HOL renamed to Old_HOL;
  1721 
  1722 * The new version of HOL (previously called CHOL) uses a curried syntax
  1723 for functions.  Application looks like f a b instead of f(a,b);
  1724 
  1725 * Mutually recursive inductive definitions finally work in HOL;
  1726 
  1727 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1728 translates to the operator "split";
  1729 
  1730 
  1731 
  1732 New in Isabelle94-3
  1733 -------------------
  1734 
  1735 * new infix operator, addss, allowing the classical reasoner to
  1736 perform simplification at each step of its search.  Example:
  1737         fast_tac (cs addss ss)
  1738 
  1739 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1740 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1741 look like (a,b) instead of <a,b>;
  1742 
  1743 * PLEASE NOTE: CHOL will eventually replace HOL!
  1744 
  1745 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1746 It translates to the operator "split".  A new theory of integers is available;
  1747 
  1748 * In ZF, integer numerals now denote two's-complement binary integers.
  1749 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1750 
  1751 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1752 of the Axiom of Choice;
  1753 
  1754 
  1755 
  1756 New in Isabelle94-2
  1757 -------------------
  1758 
  1759 * Significantly faster resolution;
  1760 
  1761 * the different sections in a .thy file can now be mixed and repeated
  1762 freely;
  1763 
  1764 * Database of theorems for FOL, HOL and ZF.  New
  1765 commands including qed, qed_goal and bind_thm store theorems in the database.
  1766 
  1767 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1768 a given theory (thms_of), or find out what theory a theorem was proved in
  1769 (theory_of_thm);
  1770 
  1771 * Bugs fixed in the inductive definition and datatype packages;
  1772 
  1773 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1774 and HOL_dup_cs obsolete;
  1775 
  1776 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1777 have been removed;
  1778 
  1779 * Simpler definition of function space in ZF;
  1780 
  1781 * new results about cardinal and ordinal arithmetic in ZF;
  1782 
  1783 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1784 types;
  1785 
  1786 
  1787 $Id$