NEWS
author wenzelm
Tue Aug 07 22:41:46 2001 +0200 (2001-08-07)
changeset 11474 d15bb7695339
parent 11437 2338bce575ae
child 11475 11402be6e4b0
permissions -rw-r--r--
tuned;
     1 
     2 Isabelle NEWS -- history user-relevant changes
     3 ==============================================
     4 
     5 New in Isabelle2001 (?? 2001)
     6 -----------------------------
     7 
     8 *** HOL ***
     9 
    10 * HOL: added "The" definite description operator;
    11 
    12 * HOL: made split_all_tac safe. EXISTING PROOFS MAY FAIL OR LOOP, so in this
    13   (rare) case use   delSWrapper "split_all_tac" addSbefore 
    14                     ("unsafe_split_all_tac", unsafe_split_all_tac)
    15 
    16 * HOL: added safe wrapper "split_conv_tac" to claset.  EXISTING PROOFS
    17 MAY FAIL;
    18 
    19 * HOL: introduced f^n = f o ... o f
    20   WARNING: due to the limits of Isabelle's type classes, ^ on functions and
    21   relations has too general a domain, namely ('a * 'b)set and 'a => 'b.
    22   This means that it may be necessary to attach explicit type constraints.
    23 
    24 * HOL records: fix problem with user translations by making field
    25 names appear as syntactic conststants;
    26 
    27 * HOL/GroupTheory: group theory examples including Sylow's theorem, by
    28 Florian Kammueller;
    29 
    30 
    31 *** ZF ***
    32 
    33 * ZF: the integer library now covers quotients and remainders, with
    34 many laws relating division to addition, multiplication, etc.;
    35 
    36 
    37 *** General ***
    38 
    39 * Classical reasoner: renamed addaltern to addafter, addSaltern to
    40 addSafter;
    41 
    42 * print modes "type_brackets" and "no_type_brackets" control output of
    43 nested => (types); the default behaviour is "brackets";
    44 
    45 
    46 
    47 New in Isabelle99-2 (February 2001)
    48 -----------------------------------
    49 
    50 *** Overview of INCOMPATIBILITIES ***
    51 
    52 * HOL: please note that theories in the Library and elsewhere often use the
    53 new-style (Isar) format; to refer to their theorems in an ML script you must
    54 bind them to ML identifers by e.g.	val thm_name = thm "thm_name";
    55 
    56 * HOL: inductive package no longer splits induction rule aggressively,
    57 but only as far as specified by the introductions given; the old
    58 format may be recovered via ML function complete_split_rule or attribute
    59 'split_rule (complete)';
    60 
    61 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
    62 gfp_Tarski to gfp_unfold;
    63 
    64 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
    65 
    66 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
    67 relation); infix "^^" has been renamed "``"; infix "``" has been
    68 renamed "`"; "univalent" has been renamed "single_valued";
    69 
    70 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
    71 operation;
    72 
    73 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
    74 
    75 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
    76 
    77 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
    78 consequence, it is no longer monotonic wrt. the local goal context
    79 (which is now passed through the inductive cases);
    80 
    81 * Document preparation: renamed standard symbols \<ll> to \<lless> and
    82 \<gg> to \<ggreater>;
    83 
    84 
    85 *** Document preparation ***
    86 
    87 * \isabellestyle{NAME} selects version of Isabelle output (currently
    88 available: are "it" for near math-mode best-style output, "sl" for
    89 slanted text style, and "tt" for plain type-writer; if no
    90 \isabellestyle command is given, output is according to slanted
    91 type-writer);
    92 
    93 * support sub/super scripts (for single symbols only), input syntax is
    94 like this: "A\<^sup>*" or "A\<^sup>\<star>";
    95 
    96 * some more standard symbols; see Appendix A of the system manual for
    97 the complete list of symbols defined in isabellesym.sty;
    98 
    99 * improved isabelle style files; more abstract symbol implementation
   100 (should now use \isamath{...} and \isatext{...} in custom symbol
   101 definitions);
   102 
   103 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   104 state; Note that presentation of goal states does not conform to
   105 actual human-readable proof documents.  Please do not include goal
   106 states into document output unless you really know what you are doing!
   107 
   108 * proper indentation of antiquoted output with proportional LaTeX
   109 fonts;
   110 
   111 * no_document ML operator temporarily disables LaTeX document
   112 generation;
   113 
   114 * isatool unsymbolize tunes sources for plain ASCII communication;
   115 
   116 
   117 *** Isar ***
   118 
   119 * Pure: Isar now suffers initial goal statements to contain unbound
   120 schematic variables (this does not conform to actual readable proof
   121 documents, due to unpredictable outcome and non-compositional proof
   122 checking); users who know what they are doing may use schematic goals
   123 for Prolog-style synthesis of proven results;
   124 
   125 * Pure: assumption method (an implicit finishing) now handles actual
   126 rules as well;
   127 
   128 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   129 initial goal, declare "that" only as Pure intro (only for single
   130 steps); the "that" rule assumption may now be involved in implicit
   131 finishing, thus ".." becomes a feasible for trivial obtains;
   132 
   133 * Pure: default proof step now includes 'intro_classes'; thus trivial
   134 instance proofs may be performed by "..";
   135 
   136 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   137 statements as well;
   138 
   139 * Pure: more robust selection of calculational rules;
   140 
   141 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   142 rule (as well as the assumption rule);
   143 
   144 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   145 lemmas, using the graph browser tool;
   146 
   147 * Pure: predict failure of "show" in interactive mode;
   148 
   149 * Pure: 'thms_containing' now takes actual terms as arguments;
   150 
   151 * HOL: improved method 'induct' --- now handles non-atomic goals
   152 (potential INCOMPATIBILITY); tuned error handling;
   153 
   154 * HOL: cases and induct rules now provide explicit hints about the
   155 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   156 any remaining facts are inserted into the goal verbatim;
   157 
   158 * HOL: local contexts (aka cases) may now contain term bindings as
   159 well; the 'cases' and 'induct' methods new provide a ?case binding for
   160 the result to be shown in each case;
   161 
   162 * HOL: added 'recdef_tc' command;
   163 
   164 * isatool convert assists in eliminating legacy ML scripts;
   165 
   166 
   167 *** HOL ***
   168 
   169 * HOL/Library: a collection of generic theories to be used together
   170 with main HOL; the theory loader path already includes this directory
   171 by default; the following existing theories have been moved here:
   172 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   173 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   174 
   175 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   176 modelling and verification task performed in Isabelle/HOL +
   177 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   178 
   179 * HOL/Algebra: special summation operator SUM no longer exists, it has
   180 been replaced by setsum; infix 'assoc' now has priority 50 (like
   181 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   182 'domain', this makes the theory consistent with mathematical
   183 literature;
   184 
   185 * HOL basics: added overloaded operations "inverse" and "divide"
   186 (infix "/"), syntax for generic "abs" operation, generic summation
   187 operator \<Sum>;
   188 
   189 * HOL/typedef: simplified package, provide more useful rules (see also
   190 HOL/subset.thy);
   191 
   192 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   193 now expressed as a proper nested rule (old-style tactic scripts may
   194 require atomize_strip_tac to cope with non-atomic premises);
   195 
   196 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   197 to "split_conv" (old name still available for compatibility);
   198 
   199 * HOL: improved concrete syntax for strings (e.g. allows translation
   200 rules with string literals);
   201 
   202 * HOL-Hyperreal: a new target, extending HOL-Real with the hyperreals
   203 and Fleuriot's mechanization of analysis;
   204 
   205 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   206 
   207 
   208 *** CTT ***
   209 
   210 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   211 "lam" is displayed as TWO lambda-symbols
   212 
   213 * CTT: theory Main now available, containing everything (that is, Bool
   214 and Arith);
   215 
   216 
   217 *** General ***
   218 
   219 * Pure: the Simplifier has been implemented properly as a derived rule
   220 outside of the actual kernel (at last!); the overall performance
   221 penalty in practical applications is about 50%, while reliability of
   222 the Isabelle inference kernel has been greatly improved;
   223 
   224 * print modes "brackets" and "no_brackets" control output of nested =>
   225 (types) and ==> (props); the default behaviour is "brackets";
   226 
   227 * Provers: fast_tac (and friends) now handle actual object-logic rules
   228 as assumptions as well;
   229 
   230 * system: support Poly/ML 4.0;
   231 
   232 * system: isatool install handles KDE version 1 or 2;
   233 
   234 
   235 
   236 New in Isabelle99-1 (October 2000)
   237 ----------------------------------
   238 
   239 *** Overview of INCOMPATIBILITIES ***
   240 
   241 * HOL: simplification of natural numbers is much changed; to partly
   242 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   243 issue the following ML commands:
   244 
   245   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   246   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   247 
   248 * HOL: simplification no longer dives into case-expressions; this is
   249 controlled by "t.weak_case_cong" for each datatype t;
   250 
   251 * HOL: nat_less_induct renamed to less_induct;
   252 
   253 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   254 fixsome to patch .thy and .ML sources automatically;
   255 
   256   select_equality  -> some_equality
   257   select_eq_Ex     -> some_eq_ex
   258   selectI2EX       -> someI2_ex
   259   selectI2         -> someI2
   260   selectI          -> someI
   261   select1_equality -> some1_equality
   262   Eps_sym_eq       -> some_sym_eq_trivial
   263   Eps_eq           -> some_eq_trivial
   264 
   265 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   266 
   267 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   268 instead);
   269 
   270 * HOL: the recursion equations generated by 'recdef' are now called
   271 f.simps instead of f.rules;
   272 
   273 * HOL: qed_spec_mp now also handles bounded ALL as well;
   274 
   275 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   276 sometimes be needed;
   277 
   278 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   279 
   280 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   281 
   282 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   283 product is now "<*>" instead of "Times"; the lexicographic product is
   284 now "<*lex*>" instead of "**";
   285 
   286 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   287 of main HOL, but was unused); better use HOL's datatype package;
   288 
   289 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   290 the old syntax may be recovered as follows:
   291 
   292   syntax (symbols)
   293     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   294       (infixl "\\<oplus>" 100)
   295 
   296 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   297 
   298 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   299 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   300 internally;
   301 
   302 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   303 changed from A/r to A//r;
   304 
   305 * ZF: new treatment of arithmetic (nat & int) may break some old
   306 proofs;
   307 
   308 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   309 rulify -> rule_format, elimify -> elim_format, ...);
   310 
   311 * Isar/Provers: intro/elim/dest attributes changed; renamed
   312 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   313 should have to change intro!! to intro? only); replaced "delrule" by
   314 "rule del";
   315 
   316 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   317 
   318 * Provers: strengthened force_tac by using new first_best_tac;
   319 
   320 * LaTeX document preparation: several changes of isabelle.sty (see
   321 lib/texinputs);
   322 
   323 
   324 *** Document preparation ***
   325 
   326 * formal comments (text blocks etc.) in new-style theories may now
   327 contain antiquotations of thm/prop/term/typ/text to be presented
   328 according to latex print mode; concrete syntax is like this:
   329 @{term[show_types] "f(x) = a + x"};
   330 
   331 * isatool mkdir provides easy setup of Isabelle session directories,
   332 including proper document sources;
   333 
   334 * generated LaTeX sources are now deleted after successful run
   335 (isatool document -c); may retain a copy somewhere else via -D option
   336 of isatool usedir;
   337 
   338 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   339 style files, achieving self-contained LaTeX sources and simplifying
   340 LaTeX debugging;
   341 
   342 * old-style theories now produce (crude) LaTeX output as well;
   343 
   344 * browser info session directories are now self-contained (may be put
   345 on WWW server seperately); improved graphs of nested sessions; removed
   346 graph for 'all sessions';
   347 
   348 * several improvements in isabelle style files; \isabellestyle{it}
   349 produces fake math mode output; \isamarkupheader is now \section by
   350 default; see lib/texinputs/isabelle.sty etc.;
   351 
   352 
   353 *** Isar ***
   354 
   355 * Isar/Pure: local results and corresponding term bindings are now
   356 subject to Hindley-Milner polymorphism (similar to ML); this
   357 accommodates incremental type-inference very nicely;
   358 
   359 * Isar/Pure: new derived language element 'obtain' supports
   360 generalized existence reasoning;
   361 
   362 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   363 support accumulation of results, without applying any rules yet;
   364 useful to collect intermediate results without explicit name
   365 references, and for use with transitivity rules with more than 2
   366 premises;
   367 
   368 * Isar/Pure: scalable support for case-analysis type proofs: new
   369 'case' language element refers to local contexts symbolically, as
   370 produced by certain proof methods; internally, case names are attached
   371 to theorems as "tags";
   372 
   373 * Isar/Pure: theory command 'hide' removes declarations from
   374 class/type/const name spaces;
   375 
   376 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   377 indicate potential overloading;
   378 
   379 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   380 
   381 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   382 "{a,b,c}" instead of {a,b,c};
   383 
   384 * Isar/Pure now provides its own version of intro/elim/dest
   385 attributes; useful for building new logics, but beware of confusion
   386 with the version in Provers/classical;
   387 
   388 * Isar/Pure: the local context of (non-atomic) goals is provided via
   389 case name 'antecedent';
   390 
   391 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   392 to the current context is now done automatically);
   393 
   394 * Isar/Pure: theory command 'method_setup' provides a simple interface
   395 for definining proof methods in ML;
   396 
   397 * Isar/Provers: intro/elim/dest attributes changed; renamed
   398 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   399 most cases, one should have to change intro!! to intro? only);
   400 replaced "delrule" by "rule del";
   401 
   402 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   403 'symmetric' attribute (the latter supercedes [RS sym]);
   404 
   405 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   406 method modifier); 'simp' method: 'only:' modifier removes loopers as
   407 well (including splits);
   408 
   409 * Isar/Provers: Simplifier and Classical methods now support all kind
   410 of modifiers used in the past, including 'cong', 'iff', etc.
   411 
   412 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   413 of Simplifier and Classical reasoner);
   414 
   415 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   416 now support named cases; major packages (inductive, datatype, primrec,
   417 recdef) support case names and properly name parameters;
   418 
   419 * Isar/HOL: new transitivity rules for substitution in inequalities --
   420 monotonicity conditions are extracted to be proven at end of
   421 calculations;
   422 
   423 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   424 method anyway;
   425 
   426 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   427 split_if split_if_asm; datatype package provides theorems foo.splits =
   428 foo.split foo.split_asm for each datatype;
   429 
   430 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   431 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   432 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   433 use "(cases (simplified))" method in proper proof texts);
   434 
   435 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   436 
   437 * Isar: names of theorems etc. may be natural numbers as well;
   438 
   439 * Isar: 'pr' command: optional arguments for goals_limit and
   440 ProofContext.prems_limit; no longer prints theory contexts, but only
   441 proof states;
   442 
   443 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   444 additional print modes to be specified; e.g. "pr(latex)" will print
   445 proof state according to the Isabelle LaTeX style;
   446 
   447 * Isar: improved support for emulating tactic scripts, including proof
   448 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   449 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   450 (for HOL datatypes);
   451 
   452 * Isar: simplified (more robust) goal selection of proof methods: 1st
   453 goal, all goals, or explicit goal specifier (tactic emulation); thus
   454 'proof method scripts' have to be in depth-first order;
   455 
   456 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   457 
   458 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   459 should instead use individual commands for printing items
   460 (print_commands, print_methods etc.);
   461 
   462 * Isar: added 'nothing' --- the empty list of theorems;
   463 
   464 
   465 *** HOL ***
   466 
   467 * HOL/MicroJava: formalization of a fragment of Java, together with a
   468 corresponding virtual machine and a specification of its bytecode
   469 verifier and a lightweight bytecode verifier, including proofs of
   470 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   471 Cornelia Pusch (see also the homepage of project Bali at
   472 http://isabelle.in.tum.de/Bali/);
   473 
   474 * HOL/Algebra: new theory of rings and univariate polynomials, by
   475 Clemens Ballarin;
   476 
   477 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   478 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   479 Rasmussen;
   480 
   481 * HOL/Lattice: fundamental concepts of lattice theory and order
   482 structures, including duals, properties of bounds versus algebraic
   483 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   484 Theorem for complete lattices etc.; may also serve as a demonstration
   485 for abstract algebraic reasoning using axiomatic type classes, and
   486 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   487 
   488 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   489 von Oheimb;
   490 
   491 * HOL/IMPP: extension of IMP with local variables and mutually
   492 recursive procedures, by David von Oheimb;
   493 
   494 * HOL/Lambda: converted into new-style theory and document;
   495 
   496 * HOL/ex/Multiquote: example of multiple nested quotations and
   497 anti-quotations -- basically a generalized version of de-Bruijn
   498 representation; very useful in avoiding lifting of operations;
   499 
   500 * HOL/record: added general record equality rule to simpset; fixed
   501 select-update simplification procedure to handle extended records as
   502 well; admit "r" as field name;
   503 
   504 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   505 other numeric types and also as the identity of groups, rings, etc.;
   506 
   507 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   508 Types nat and int belong to this axclass;
   509 
   510 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   511    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   512    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   513   two terms #m*u and #n*u are replaced by #(m+n)*u
   514     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   515   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   516     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   517 
   518 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   519 powerful prover for predicate logic but knows nothing of clasets; see
   520 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   521 
   522 * HOL: new version of "case_tac" subsumes both boolean case split and
   523 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   524 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   525 
   526 * HOL: simplification no longer dives into case-expressions: only the
   527 selector expression is simplified, but not the remaining arms; to
   528 enable full simplification of case-expressions for datatype t, you may
   529 remove t.weak_case_cong from the simpset, either globally (Delcongs
   530 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   531 
   532 * HOL/recdef: the recursion equations generated by 'recdef' for
   533 function 'f' are now called f.simps instead of f.rules; if all
   534 termination conditions are proved automatically, these simplification
   535 rules are added to the simpset, as in primrec; rules may be named
   536 individually as well, resulting in a separate list of theorems for
   537 each equation;
   538 
   539 * HOL/While is a new theory that provides a while-combinator. It
   540 permits the definition of tail-recursive functions without the
   541 provision of a termination measure. The latter is necessary once the
   542 invariant proof rule for while is applied.
   543 
   544 * HOL: new (overloaded) notation for the set of elements below/above
   545 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   546 
   547 * HOL: theorems impI, allI, ballI bound as "strip";
   548 
   549 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   550 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   551 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   552 
   553 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   554 
   555 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   556 main HOL, but was unused);
   557 
   558 * HOL: fewer consts declared as global (e.g. have to refer to
   559 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   560 
   561 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   562 in case of overlap with user translations (e.g. judgements over
   563 tuples); (note that the underlying logical represenation is still
   564 bogus);
   565 
   566 
   567 *** ZF ***
   568 
   569 * ZF: simplification automatically cancels common terms in arithmetic
   570 expressions over nat and int;
   571 
   572 * ZF: new treatment of nat to minimize type-checking: all operators
   573 coerce their operands to a natural number using the function natify,
   574 making the algebraic laws unconditional;
   575 
   576 * ZF: as above, for int: operators coerce their operands to an integer
   577 using the function intify;
   578 
   579 * ZF: the integer library now contains many of the usual laws for the
   580 orderings, including $<=, and monotonicity laws for $+ and $*;
   581 
   582 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
   583 simplification;
   584 
   585 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
   586 to the simplifier and classical reasoner simultaneously;
   587 
   588 
   589 *** General ***
   590 
   591 * Provers: blast_tac now handles actual object-logic rules as
   592 assumptions; note that auto_tac uses blast_tac internally as well;
   593 
   594 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
   595 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
   596 
   597 * Provers: delrules now handles destruct rules as well (no longer need
   598 explicit make_elim);
   599 
   600 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
   601   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   602 use instead the strong form,
   603   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   604 in HOL, FOL and ZF the function cla_make_elim will create such rules
   605 from destruct-rules;
   606 
   607 * Provers: Simplifier.easy_setup provides a fast path to basic
   608 Simplifier setup for new object-logics;
   609 
   610 * Pure: AST translation rules no longer require constant head on LHS;
   611 
   612 * Pure: improved name spaces: ambiguous output is qualified; support
   613 for hiding of names;
   614 
   615 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
   616 XSYMBOL_HOME; no longer need to do manual configuration in most
   617 situations;
   618 
   619 * system: compression of ML heaps images may now be controlled via -c
   620 option of isabelle and isatool usedir (currently only observed by
   621 Poly/ML);
   622 
   623 * system: isatool installfonts may handle X-Symbol fonts as well (very
   624 useful for remote X11);
   625 
   626 * system: provide TAGS file for Isabelle sources;
   627 
   628 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
   629 order;
   630 
   631 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
   632 timing flag supersedes proof_timing and Toplevel.trace;
   633 
   634 * ML: new combinators |>> and |>>> for incremental transformations
   635 with secondary results (e.g. certain theory extensions):
   636 
   637 * ML: PureThy.add_defs gets additional argument to indicate potential
   638 overloading (usually false);
   639 
   640 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
   641 results;
   642 
   643 
   644 
   645 New in Isabelle99 (October 1999)
   646 --------------------------------
   647 
   648 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   649 
   650 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
   651 are no longer simplified.  (This allows the simplifier to unfold recursive
   652 functional programs.)  To restore the old behaviour, declare
   653 
   654     Delcongs [if_weak_cong];
   655 
   656 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
   657 complement;
   658 
   659 * HOL: the predicate "inj" is now defined by translation to "inj_on";
   660 
   661 * HOL/datatype: mutual_induct_tac no longer exists --
   662   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
   663 
   664 * HOL/typedef: fixed type inference for representing set; type
   665 arguments now have to occur explicitly on the rhs as type constraints;
   666 
   667 * ZF: The con_defs part of an inductive definition may no longer refer
   668 to constants declared in the same theory;
   669 
   670 * HOL, ZF: the function mk_cases, generated by the inductive
   671 definition package, has lost an argument.  To simplify its result, it
   672 uses the default simpset instead of a supplied list of theorems.
   673 
   674 * HOL/List: the constructors of type list are now Nil and Cons;
   675 
   676 * Simplifier: the type of the infix ML functions
   677         setSSolver addSSolver setSolver addSolver
   678 is now  simpset * solver -> simpset  where `solver' is a new abstract type
   679 for packaging solvers. A solver is created via
   680         mk_solver: string -> (thm list -> int -> tactic) -> solver
   681 where the string argument is only a comment.
   682 
   683 
   684 *** Proof tools ***
   685 
   686 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
   687 decision procedure for linear arithmetic. Currently it is used for
   688 types `nat', `int', and `real' in HOL (see below); it can, should and
   689 will be instantiated for other types and logics as well.
   690 
   691 * The simplifier now accepts rewrite rules with flexible heads, eg
   692      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
   693   They are applied like any rule with a non-pattern lhs, i.e. by first-order
   694   matching.
   695 
   696 
   697 *** General ***
   698 
   699 * New Isabelle/Isar subsystem provides an alternative to traditional
   700 tactical theorem proving; together with the ProofGeneral/isar user
   701 interface it offers an interactive environment for developing human
   702 readable proof documents (Isar == Intelligible semi-automated
   703 reasoning); for further information see isatool doc isar-ref,
   704 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
   705 
   706 * improved and simplified presentation of theories: better HTML markup
   707 (including colors), graph views in several sizes; isatool usedir now
   708 provides a proper interface for user theories (via -P option); actual
   709 document preparation based on (PDF)LaTeX is available as well (for
   710 new-style theories only); see isatool doc system for more information;
   711 
   712 * native support for Proof General, both for classic Isabelle and
   713 Isabelle/Isar;
   714 
   715 * ML function thm_deps visualizes dependencies of theorems and lemmas,
   716 using the graph browser tool;
   717 
   718 * Isabelle manuals now also available as PDF;
   719 
   720 * theory loader rewritten from scratch (may not be fully
   721 bug-compatible); old loadpath variable has been replaced by show_path,
   722 add_path, del_path, reset_path functions; new operations such as
   723 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
   724 isatool doc ref);
   725 
   726 * improved isatool install: option -k creates KDE application icon,
   727 option -p DIR installs standalone binaries;
   728 
   729 * added ML_PLATFORM setting (useful for cross-platform installations);
   730 more robust handling of platform specific ML images for SML/NJ;
   731 
   732 * the settings environment is now statically scoped, i.e. it is never
   733 created again in sub-processes invoked from isabelle, isatool, or
   734 Isabelle;
   735 
   736 * path element specification '~~' refers to '$ISABELLE_HOME';
   737 
   738 * in locales, the "assumes" and "defines" parts may be omitted if
   739 empty;
   740 
   741 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   742 long arrows);
   743 
   744 * new print_mode "HTML";
   745 
   746 * new flag show_tags controls display of tags of theorems (which are
   747 basically just comments that may be attached by some tools);
   748 
   749 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   750 mode and goal output format:
   751 
   752 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   753 244c244
   754 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   755 ---
   756 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   757 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   758 181c181
   759 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   760 ---
   761 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   762 
   763 * function bind_thms stores lists of theorems (cf. bind_thm);
   764 
   765 * new shorthand tactics ftac, eatac, datac, fatac;
   766 
   767 * qed (and friends) now accept "" as result name; in that case the
   768 theorem is not stored, but proper checks and presentation of the
   769 result still apply;
   770 
   771 * theorem database now also indexes constants "Trueprop", "all",
   772 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   773 
   774 
   775 *** HOL ***
   776 
   777 ** HOL arithmetic **
   778 
   779 * There are now decision procedures for linear arithmetic over nat and
   780 int:
   781 
   782 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   783 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   784 are treated as atomic; subformulae not involving type `nat' or `int'
   785 are ignored; quantified subformulae are ignored unless they are
   786 positive universal or negative existential. The tactic has to be
   787 invoked by hand and can be a little bit slow. In particular, the
   788 running time is exponential in the number of occurrences of `min' and
   789 `max', and `-' on `nat'.
   790 
   791 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   792 (negated) (in)equalities among the premises and the conclusion into
   793 account (i.e. no compound formulae) and does not know about `min' and
   794 `max', and `-' on `nat'. It is fast and is used automatically by the
   795 simplifier.
   796 
   797 NB: At the moment, these decision procedures do not cope with mixed
   798 nat/int formulae where the two parts interact, such as `m < n ==>
   799 int(m) < int(n)'.
   800 
   801 * HOL/Numeral provides a generic theory of numerals (encoded
   802 efficiently as bit strings); setup for types nat/int/real is in place;
   803 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   804 int, existing theories and proof scripts may require a few additional
   805 type constraints;
   806 
   807 * integer division and remainder can now be performed on constant
   808 arguments;
   809 
   810 * many properties of integer multiplication, division and remainder
   811 are now available;
   812 
   813 * An interface to the Stanford Validity Checker (SVC) is available through the
   814 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   815 are proved automatically.  SVC must be installed separately, and its results
   816 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   817 invocation of the underlying oracle).  For SVC see
   818   http://verify.stanford.edu/SVC
   819 
   820 * IsaMakefile: the HOL-Real target now builds an actual image;
   821 
   822 
   823 ** HOL misc **
   824 
   825 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   826 (in Isabelle/Isar) -- by Gertrud Bauer;
   827 
   828 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   829 analysis for assembly languages with subtypes;
   830 
   831 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   832 -- avoids syntactic ambiguities and treats state, transition, and
   833 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   834 changed syntax and (many) tactics;
   835 
   836 * HOL/inductive: Now also handles more general introduction rules such
   837   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
   838   theorems are now maintained within the theory (maintained via the
   839   "mono" attribute);
   840 
   841 * HOL/datatype: Now also handles arbitrarily branching datatypes
   842   (using function types) such as
   843 
   844   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
   845 
   846 * HOL/record: record_simproc (part of the default simpset) takes care
   847 of selectors applied to updated records; record_split_tac is no longer
   848 part of the default claset; update_defs may now be removed from the
   849 simpset in many cases; COMPATIBILITY: old behavior achieved by
   850 
   851   claset_ref () := claset() addSWrapper record_split_wrapper;
   852   Delsimprocs [record_simproc]
   853 
   854 * HOL/typedef: fixed type inference for representing set; type
   855 arguments now have to occur explicitly on the rhs as type constraints;
   856 
   857 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
   858 names rather than an ML expression;
   859 
   860 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
   861 supplied later.  Program schemes can be defined, such as
   862     "While B C s = (if B s then While B C (C s) else s)"
   863 where the well-founded relation can be chosen after B and C have been given.
   864 
   865 * HOL/List: the constructors of type list are now Nil and Cons;
   866 INCOMPATIBILITY: while [] and infix # syntax is still there, of
   867 course, ML tools referring to List.list.op # etc. have to be adapted;
   868 
   869 * HOL_quantifiers flag superseded by "HOL" print mode, which is
   870 disabled by default; run isabelle with option -m HOL to get back to
   871 the original Gordon/HOL-style output;
   872 
   873 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
   874 ALL x<=y. P, EX x<y. P, EX x<=y. P;
   875 
   876 * HOL basic syntax simplified (more orthogonal): all variants of
   877 All/Ex now support plain / symbolic / HOL notation; plain syntax for
   878 Eps operator is provided as well: "SOME x. P[x]";
   879 
   880 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
   881 
   882 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
   883 thus available for user theories;
   884 
   885 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
   886 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
   887 time;
   888 
   889 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
   890 several times and then mp;
   891 
   892 
   893 *** LK ***
   894 
   895 * the notation <<...>> is now available as a notation for sequences of
   896 formulas;
   897 
   898 * the simplifier is now installed
   899 
   900 * the axiom system has been generalized (thanks to Soren Heilmann)
   901 
   902 * the classical reasoner now has a default rule database
   903 
   904 
   905 *** ZF ***
   906 
   907 * new primrec section allows primitive recursive functions to be given
   908 directly (as in HOL) over datatypes and the natural numbers;
   909 
   910 * new tactics induct_tac and exhaust_tac for induction (or case
   911 analysis) over datatypes and the natural numbers;
   912 
   913 * the datatype declaration of type T now defines the recursor T_rec;
   914 
   915 * simplification automatically does freeness reasoning for datatype
   916 constructors;
   917 
   918 * automatic type-inference, with AddTCs command to insert new
   919 type-checking rules;
   920 
   921 * datatype introduction rules are now added as Safe Introduction rules
   922 to the claset;
   923 
   924 * the syntax "if P then x else y" is now available in addition to
   925 if(P,x,y);
   926 
   927 
   928 *** Internal programming interfaces ***
   929 
   930 * tuned simplifier trace output; new flag debug_simp;
   931 
   932 * structures Vartab / Termtab (instances of TableFun) offer efficient
   933 tables indexed by indexname_ord / term_ord (compatible with aconv);
   934 
   935 * AxClass.axclass_tac lost the theory argument;
   936 
   937 * tuned current_goals_markers semantics: begin / end goal avoids
   938 printing empty lines;
   939 
   940 * removed prs and prs_fn hook, which was broken because it did not
   941 include \n in its semantics, forcing writeln to add one
   942 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
   943 string -> unit if you really want to output text without newline;
   944 
   945 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
   946 plain output, interface builders may have to enable 'isabelle_font'
   947 mode to get Isabelle font glyphs as before;
   948 
   949 * refined token_translation interface; INCOMPATIBILITY: output length
   950 now of type real instead of int;
   951 
   952 * theory loader actions may be traced via new ThyInfo.add_hook
   953 interface (see src/Pure/Thy/thy_info.ML); example application: keep
   954 your own database of information attached to *whole* theories -- as
   955 opposed to intra-theory data slots offered via TheoryDataFun;
   956 
   957 * proper handling of dangling sort hypotheses (at last!);
   958 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
   959 extra sort hypotheses that can be witnessed from the type signature;
   960 the force_strip_shyps flag is gone, any remaining shyps are simply
   961 left in the theorem (with a warning issued by strip_shyps_warning);
   962 
   963 
   964 
   965 New in Isabelle98-1 (October 1998)
   966 ----------------------------------
   967 
   968 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   969 
   970 * several changes of automated proof tools;
   971 
   972 * HOL: major changes to the inductive and datatype packages, including
   973 some minor incompatibilities of theory syntax;
   974 
   975 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
   976 called `inj_on';
   977 
   978 * HOL: removed duplicate thms in Arith:
   979   less_imp_add_less  should be replaced by  trans_less_add1
   980   le_imp_add_le      should be replaced by  trans_le_add1
   981 
   982 * HOL: unary minus is now overloaded (new type constraints may be
   983 required);
   984 
   985 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
   986 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
   987 now taken as an integer constant.
   988 
   989 * Pure: ML function 'theory_of' renamed to 'theory';
   990 
   991 
   992 *** Proof tools ***
   993 
   994 * Simplifier:
   995   1. Asm_full_simp_tac is now more aggressive.
   996      1. It will sometimes reorient premises if that increases their power to
   997         simplify.
   998      2. It does no longer proceed strictly from left to right but may also
   999         rotate premises to achieve further simplification.
  1000      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1001      old Asm_full_simp_tac in that it does not rotate premises.
  1002   2. The simplifier now knows a little bit about nat-arithmetic.
  1003 
  1004 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1005 allows for selected deletion of wrappers, by introduction of names for
  1006 wrapper functionals.  This implies that addbefore, addSbefore,
  1007 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1008 and that adding two tactics with the same name overwrites the first
  1009 one (emitting a warning).
  1010   type wrapper = (int -> tactic) -> (int -> tactic)
  1011   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1012   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1013   delWrapper, delSWrapper: claset *  string            -> claset
  1014   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1015 
  1016 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1017 semantics; addbefore now affects only the unsafe part of step_tac
  1018 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1019 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1020 by Force_tac;
  1021 
  1022 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1023 compWrapper; added safe wrapper (and access functions for it);
  1024 
  1025 * HOL/split_all_tac is now much faster and fails if there is nothing
  1026 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1027 and the names of the automatically generated variables have changed.
  1028 split_all_tac has moved within claset() from unsafe wrappers to safe
  1029 wrappers, which means that !!-bound variables are split much more
  1030 aggressively, and safe_tac and clarify_tac now split such variables.
  1031 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1032 Note: the same holds for record_split_tac, which does the job of
  1033 split_all_tac for record fields.
  1034 
  1035 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1036 permanently to the default simpset using Addsplits just like
  1037 Addsimps. They can be removed via Delsplits just like
  1038 Delsimps. Lower-case versions are also available.
  1039 
  1040 * HOL/Simplifier: The rule split_if is now part of the default
  1041 simpset. This means that the simplifier will eliminate all occurrences
  1042 of if-then-else in the conclusion of a goal. To prevent this, you can
  1043 either remove split_if completely from the default simpset by
  1044 `Delsplits [split_if]' or remove it in a specific call of the
  1045 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1046 other case splitting rules to/from the default simpset: every datatype
  1047 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1048 t is the name of the datatype).
  1049 
  1050 * Classical reasoner / Simplifier combination: new force_tac (and
  1051 derivatives Force_tac, force) combines rewriting and classical
  1052 reasoning (and whatever other tools) similarly to auto_tac, but is
  1053 aimed to solve the given subgoal completely.
  1054 
  1055 
  1056 *** General ***
  1057 
  1058 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1059 and `goalw': the theory is no longer needed as an explicit argument -
  1060 the current theory context is used; assumptions are no longer returned
  1061 at the ML-level unless one of them starts with ==> or !!; it is
  1062 recommended to convert to these new commands using isatool fixgoal
  1063 (backup your sources first!);
  1064 
  1065 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1066 the current theory context, and 'theory' to lookup stored theories;
  1067 
  1068 * new theory section 'locale' for declaring constants, assumptions and
  1069 definitions that have local scope;
  1070 
  1071 * new theory section 'nonterminals' for purely syntactic types;
  1072 
  1073 * new theory section 'setup' for generic ML setup functions
  1074 (e.g. package initialization);
  1075 
  1076 * the distribution now includes Isabelle icons: see
  1077 lib/logo/isabelle-{small,tiny}.xpm;
  1078 
  1079 * isatool install - install binaries with absolute references to
  1080 ISABELLE_HOME/bin;
  1081 
  1082 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1083 
  1084 * print mode 'emacs' reserved for Isamode;
  1085 
  1086 * support multiple print (ast) translations per constant name;
  1087 
  1088 * theorems involving oracles are now printed with a suffixed [!];
  1089 
  1090 
  1091 *** HOL ***
  1092 
  1093 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1094 
  1095 * HOL/inductive package reorganized and improved: now supports mutual
  1096 definitions such as
  1097 
  1098   inductive EVEN ODD
  1099     intrs
  1100       null "0 : EVEN"
  1101       oddI "n : EVEN ==> Suc n : ODD"
  1102       evenI "n : ODD ==> Suc n : EVEN"
  1103 
  1104 new theorem list "elims" contains an elimination rule for each of the
  1105 recursive sets; inductive definitions now handle disjunctive premises
  1106 correctly (also ZF);
  1107 
  1108 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1109 "mutual_induct" no longer exists - the induction rule is always
  1110 contained in "induct";
  1111 
  1112 
  1113 * HOL/datatype package re-implemented and greatly improved: now
  1114 supports mutually recursive datatypes such as
  1115 
  1116   datatype
  1117     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1118             | SUM ('a aexp) ('a aexp)
  1119             | DIFF ('a aexp) ('a aexp)
  1120             | NUM 'a
  1121   and
  1122     'a bexp = LESS ('a aexp) ('a aexp)
  1123             | AND ('a bexp) ('a bexp)
  1124             | OR ('a bexp) ('a bexp)
  1125 
  1126 as well as indirectly recursive datatypes such as
  1127 
  1128   datatype
  1129     ('a, 'b) term = Var 'a
  1130                   | App 'b ((('a, 'b) term) list)
  1131 
  1132 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1133 induction on mutually / indirectly recursive datatypes.
  1134 
  1135 Primrec equations are now stored in theory and can be accessed via
  1136 <function_name>.simps.
  1137 
  1138 INCOMPATIBILITIES:
  1139 
  1140   - Theories using datatypes must now have theory Datatype as an
  1141     ancestor.
  1142   - The specific <typename>.induct_tac no longer exists - use the
  1143     generic induct_tac instead.
  1144   - natE has been renamed to nat.exhaust - use exhaust_tac
  1145     instead of res_inst_tac ... natE. Note that the variable
  1146     names in nat.exhaust differ from the names in natE, this
  1147     may cause some "fragile" proofs to fail.
  1148   - The theorems split_<typename>_case and split_<typename>_case_asm
  1149     have been renamed to <typename>.split and <typename>.split_asm.
  1150   - Since default sorts of type variables are now handled correctly,
  1151     some datatype definitions may have to be annotated with explicit
  1152     sort constraints.
  1153   - Primrec definitions no longer require function name and type
  1154     of recursive argument.
  1155 
  1156 Consider using isatool fixdatatype to adapt your theories and proof
  1157 scripts to the new package (backup your sources first!).
  1158 
  1159 
  1160 * HOL/record package: considerably improved implementation; now
  1161 includes concrete syntax for record types, terms, updates; theorems
  1162 for surjective pairing and splitting !!-bound record variables; proof
  1163 support is as follows:
  1164 
  1165   1) standard conversions (selectors or updates applied to record
  1166 constructor terms) are part of the standard simpset;
  1167 
  1168   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1169 made part of standard simpset and claset via addIffs;
  1170 
  1171   3) a tactic for record field splitting (record_split_tac) is part of
  1172 the standard claset (addSWrapper);
  1173 
  1174 To get a better idea about these rules you may retrieve them via
  1175 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1176 the name of your record type.
  1177 
  1178 The split tactic 3) conceptually simplifies by the following rule:
  1179 
  1180   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1181 
  1182 Thus any record variable that is bound by meta-all will automatically
  1183 blow up into some record constructor term, consequently the
  1184 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1185 solve record problems automatically.
  1186 
  1187 
  1188 * reorganized the main HOL image: HOL/Integ and String loaded by
  1189 default; theory Main includes everything;
  1190 
  1191 * automatic simplification of integer sums and comparisons, using cancellation;
  1192 
  1193 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1194 
  1195 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1196 
  1197 * many new identities for unions, intersections, set difference, etc.;
  1198 
  1199 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1200 called split_if, split_split, split_sum_case and split_nat_case (to go
  1201 with add/delsplits);
  1202 
  1203 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1204 (?x::unit) = (); this is made part of the default simpset, which COULD
  1205 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1206 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1207 unit_abs_eta_conv is added in order to counter the effect of
  1208 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1209 %u.f();
  1210 
  1211 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1212 makes more sense);
  1213 
  1214 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1215   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1216   disjointness reasoning but breaking a few old proofs.
  1217 
  1218 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1219 to 'converse' from 'inverse' (for compatibility with ZF and some
  1220 literature);
  1221 
  1222 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1223 the well-founded relation;
  1224 
  1225 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1226     Compl A.  The "Compl" syntax remains available as input syntax for this
  1227     release ONLY.
  1228 
  1229 * HOL/Update: new theory of function updates:
  1230     f(a:=b) == %x. if x=a then b else f x
  1231 may also be iterated as in f(a:=b,c:=d,...);
  1232 
  1233 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1234 
  1235 * HOL/List:
  1236   - new function list_update written xs[i:=v] that updates the i-th
  1237     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1238   - new function `upt' written [i..j(] which generates the list
  1239     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1240     bound write [i..j], which is a shorthand for [i..j+1(].
  1241   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1242 
  1243 * HOL/Arith:
  1244   - removed 'pred' (predecessor) function;
  1245   - generalized some theorems about n-1;
  1246   - many new laws about "div" and "mod";
  1247   - new laws about greatest common divisors (see theory ex/Primes);
  1248 
  1249 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1250 instead of "inverse";
  1251 
  1252 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1253   of the multiset ordering;
  1254 
  1255 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1256   (not included by default);
  1257 
  1258 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1259 
  1260 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1261   programs, i.e. different program variables may have different types.
  1262 
  1263 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1264   [previously, this check worked only if the rewrite rule was unconditional]
  1265   Now rew can involve either definitions or equalities (either == or =).
  1266 
  1267 
  1268 *** ZF ***
  1269 
  1270 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1271   only the theorems proved on ZF.ML;
  1272 
  1273 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1274   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1275   disjointness reasoning but breaking a few old proofs.
  1276 
  1277 * ZF/Update: new theory of function updates
  1278     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1279   may also be iterated as in f(a:=b,c:=d,...);
  1280 
  1281 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1282 
  1283 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1284   [previously, this check worked only if the rewrite rule was unconditional]
  1285   Now rew can involve either definitions or equalities (either == or =).
  1286 
  1287 * case_tac provided for compatibility with HOL
  1288     (like the old excluded_middle_tac, but with subgoals swapped)
  1289 
  1290 
  1291 *** Internal programming interfaces ***
  1292 
  1293 * Pure: several new basic modules made available for general use, see
  1294 also src/Pure/README;
  1295 
  1296 * improved the theory data mechanism to support encapsulation (data
  1297 kind name replaced by private Object.kind, acting as authorization
  1298 key); new type-safe user interface via functor TheoryDataFun; generic
  1299 print_data function becomes basically useless;
  1300 
  1301 * removed global_names compatibility flag -- all theory declarations
  1302 are qualified by default;
  1303 
  1304 * module Pure/Syntax now offers quote / antiquote translation
  1305 functions (useful for Hoare logic etc. with implicit dependencies);
  1306 see HOL/ex/Antiquote for an example use;
  1307 
  1308 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1309 cterm -> thm;
  1310 
  1311 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1312 subgoal;
  1313 
  1314 * Display.print_goals function moved to Locale.print_goals;
  1315 
  1316 * standard print function for goals supports current_goals_markers
  1317 variable for marking begin of proof, end of proof, start of goal; the
  1318 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1319 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1320 for example;
  1321 
  1322 
  1323 
  1324 New in Isabelle98 (January 1998)
  1325 --------------------------------
  1326 
  1327 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1328 
  1329 * changed lexical syntax of terms / types: dots made part of long
  1330 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1331 
  1332 * simpset (and claset) reference variable replaced by functions
  1333 simpset / simpset_ref;
  1334 
  1335 * no longer supports theory aliases (via merge) and non-trivial
  1336 implicit merge of thms' signatures;
  1337 
  1338 * most internal names of constants changed due to qualified names;
  1339 
  1340 * changed Pure/Sequence interface (see Pure/seq.ML);
  1341 
  1342 
  1343 *** General Changes ***
  1344 
  1345 * hierachically structured name spaces (for consts, types, axms, thms
  1346 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1347 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1348 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1349 long_names for fully qualified output names; NOTE: ML programs
  1350 (special tactics, packages etc.) referring to internal names may have
  1351 to be adapted to cope with fully qualified names; in case of severe
  1352 backward campatibility problems try setting 'global_names' at compile
  1353 time to have enrything declared within a flat name space; one may also
  1354 fine tune name declarations in theories via the 'global' and 'local'
  1355 section;
  1356 
  1357 * reimplemented the implicit simpset and claset using the new anytype
  1358 data filed in signatures; references simpset:simpset ref etc. are
  1359 replaced by functions simpset:unit->simpset and
  1360 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1361 to patch your ML files accordingly;
  1362 
  1363 * HTML output now includes theory graph data for display with Java
  1364 applet or isatool browser; data generated automatically via isatool
  1365 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1366 
  1367 * defs may now be conditional; improved rewrite_goals_tac to handle
  1368 conditional equations;
  1369 
  1370 * defs now admits additional type arguments, using TYPE('a) syntax;
  1371 
  1372 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1373 creates a new theory node; implicit merge of thms' signatures is
  1374 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1375 transfer:theory->thm->thm in (rare) cases;
  1376 
  1377 * improved handling of draft signatures / theories; draft thms (and
  1378 ctyps, cterms) are automatically promoted to real ones;
  1379 
  1380 * slightly changed interfaces for oracles: admit many per theory, named
  1381 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1382 
  1383 * print_goals: optional output of const types (set show_consts and
  1384 show_types);
  1385 
  1386 * improved output of warnings (###) and errors (***);
  1387 
  1388 * subgoal_tac displays a warning if the new subgoal has type variables;
  1389 
  1390 * removed old README and Makefiles;
  1391 
  1392 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1393 
  1394 * removed obsolete init_pps and init_database;
  1395 
  1396 * deleted the obsolete tactical STATE, which was declared by
  1397     fun STATE tacfun st = tacfun st st;
  1398 
  1399 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1400 (which abbreviates $HOME);
  1401 
  1402 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1403 use isatool fixseq to adapt your ML programs (this works for fully
  1404 qualified references to the Sequence structure only!);
  1405 
  1406 * use_thy no longer requires writable current directory; it always
  1407 reloads .ML *and* .thy file, if either one is out of date;
  1408 
  1409 
  1410 *** Classical Reasoner ***
  1411 
  1412 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1413 tactics that use classical reasoning to simplify a subgoal without
  1414 splitting it into several subgoals;
  1415 
  1416 * Safe_tac: like safe_tac but uses the default claset;
  1417 
  1418 
  1419 *** Simplifier ***
  1420 
  1421 * added simplification meta rules:
  1422     (asm_)(full_)simplify: simpset -> thm -> thm;
  1423 
  1424 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1425 logics (again);
  1426 
  1427 * added prems argument to simplification procedures;
  1428 
  1429 * HOL, FOL, ZF: added infix function `addsplits':
  1430   instead of `<simpset> setloop (split_tac <thms>)'
  1431   you can simply write `<simpset> addsplits <thms>'
  1432 
  1433 
  1434 *** Syntax ***
  1435 
  1436 * TYPE('a) syntax for type reflection terms;
  1437 
  1438 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1439 
  1440 * pretty printer: changed order of mixfix annotation preference (again!);
  1441 
  1442 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1443 
  1444 
  1445 *** HOL ***
  1446 
  1447 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1448   with `addloop' of the simplifier to faciliate case splitting in premises.
  1449 
  1450 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1451 
  1452 * HOL/Auth: new protocol proofs including some for the Internet
  1453   protocol TLS;
  1454 
  1455 * HOL/Map: new theory of `maps' a la VDM;
  1456 
  1457 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1458 cancelling out common nat summands from =, <, <= (in)equalities, or
  1459 differences; simplification procedures nat_cancel_factor for
  1460 cancelling common factor from =, <, <= (in)equalities over natural
  1461 sums; nat_cancel contains both kinds of procedures, it is installed by
  1462 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1463 
  1464 * HOL/simplifier: terms of the form
  1465   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1466   are rewritten to
  1467   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1468   and those of the form
  1469   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1470   are rewritten to
  1471   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1472 
  1473 * HOL/datatype
  1474   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1475 
  1476   P(t_case f1 ... fn x) =
  1477      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1478         ...
  1479        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1480      )
  1481 
  1482   and a theorem `split_t_case_asm' of the form
  1483 
  1484   P(t_case f1 ... fn x) =
  1485     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1486         ...
  1487        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1488      )
  1489   which can be added to a simpset via `addsplits'. The existing theorems
  1490   expand_list_case and expand_option_case have been renamed to
  1491   split_list_case and split_option_case.
  1492 
  1493 * HOL/Arithmetic:
  1494   - `pred n' is automatically converted to `n-1'.
  1495     Users are strongly encouraged not to use `pred' any longer,
  1496     because it will disappear altogether at some point.
  1497   - Users are strongly encouraged to write "0 < n" rather than
  1498     "n ~= 0". Theorems and proof tools have been modified towards this
  1499     `standard'.
  1500 
  1501 * HOL/Lists:
  1502   the function "set_of_list" has been renamed "set" (and its theorems too);
  1503   the function "nth" now takes its arguments in the reverse order and
  1504   has acquired the infix notation "!" as in "xs!n".
  1505 
  1506 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1507 
  1508 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1509   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1510 
  1511 * HOL/record: extensible records with schematic structural subtyping
  1512 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1513 still lacks various theorems and concrete record syntax;
  1514 
  1515 
  1516 *** HOLCF ***
  1517 
  1518 * removed "axioms" and "generated by" sections;
  1519 
  1520 * replaced "ops" section by extended "consts" section, which is capable of
  1521   handling the continuous function space "->" directly;
  1522 
  1523 * domain package:
  1524   . proves theorems immediately and stores them in the theory,
  1525   . creates hierachical name space,
  1526   . now uses normal mixfix annotations (instead of cinfix...),
  1527   . minor changes to some names and values (for consistency),
  1528   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1529   . separator between mutual domain defs: changed "," to "and",
  1530   . improved handling of sort constraints;  now they have to
  1531     appear on the left-hand side of the equations only;
  1532 
  1533 * fixed LAM <x,y,zs>.b syntax;
  1534 
  1535 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1536 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1537 
  1538 
  1539 *** FOL and ZF ***
  1540 
  1541 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1542   with `addloop' of the simplifier to faciliate case splitting in premises.
  1543 
  1544 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1545 in HOL, they strip ALL and --> from proved theorems;
  1546 
  1547 
  1548 
  1549 New in Isabelle94-8 (May 1997)
  1550 ------------------------------
  1551 
  1552 *** General Changes ***
  1553 
  1554 * new utilities to build / run / maintain Isabelle etc. (in parts
  1555 still somewhat experimental); old Makefiles etc. still functional;
  1556 
  1557 * new 'Isabelle System Manual';
  1558 
  1559 * INSTALL text, together with ./configure and ./build scripts;
  1560 
  1561 * reimplemented type inference for greater efficiency, better error
  1562 messages and clean internal interface;
  1563 
  1564 * prlim command for dealing with lots of subgoals (an easier way of
  1565 setting goals_limit);
  1566 
  1567 
  1568 *** Syntax ***
  1569 
  1570 * supports alternative (named) syntax tables (parser and pretty
  1571 printer); internal interface is provided by add_modesyntax(_i);
  1572 
  1573 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1574 be used in conjunction with the Isabelle symbol font; uses the
  1575 "symbols" syntax table;
  1576 
  1577 * added token_translation interface (may translate name tokens in
  1578 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1579 the current print_mode); IMPORTANT: user print translation functions
  1580 are responsible for marking newly introduced bounds
  1581 (Syntax.mark_boundT);
  1582 
  1583 * token translations for modes "xterm" and "xterm_color" that display
  1584 names in bold, underline etc. or colors (which requires a color
  1585 version of xterm);
  1586 
  1587 * infixes may now be declared with names independent of their syntax;
  1588 
  1589 * added typed_print_translation (like print_translation, but may
  1590 access type of constant);
  1591 
  1592 
  1593 *** Classical Reasoner ***
  1594 
  1595 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  1596 some limitations.  Blast_tac...
  1597   + ignores addss, addbefore, addafter; this restriction is intrinsic
  1598   + ignores elimination rules that don't have the correct format
  1599         (the conclusion MUST be a formula variable)
  1600   + ignores types, which can make HOL proofs fail
  1601   + rules must not require higher-order unification, e.g. apply_type in ZF
  1602     [message "Function Var's argument not a bound variable" relates to this]
  1603   + its proof strategy is more general but can actually be slower
  1604 
  1605 * substitution with equality assumptions no longer permutes other
  1606 assumptions;
  1607 
  1608 * minor changes in semantics of addafter (now called addaltern); renamed
  1609 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  1610 (and access functions for it);
  1611 
  1612 * improved combination of classical reasoner and simplifier:
  1613   + functions for handling clasimpsets
  1614   + improvement of addss: now the simplifier is called _after_ the
  1615     safe steps.
  1616   + safe variant of addss called addSss: uses safe simplifications
  1617     _during_ the safe steps. It is more complete as it allows multiple
  1618     instantiations of unknowns (e.g. with slow_tac).
  1619 
  1620 *** Simplifier ***
  1621 
  1622 * added interface for simplification procedures (functions that
  1623 produce *proven* rewrite rules on the fly, depending on current
  1624 redex);
  1625 
  1626 * ordering on terms as parameter (used for ordered rewriting);
  1627 
  1628 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  1629 
  1630 * the solver is now split into a safe and an unsafe part.
  1631 This should be invisible for the normal user, except that the
  1632 functions setsolver and addsolver have been renamed to setSolver and
  1633 addSolver; added safe_asm_full_simp_tac;
  1634 
  1635 
  1636 *** HOL ***
  1637 
  1638 * a generic induction tactic `induct_tac' which works for all datatypes and
  1639 also for type `nat';
  1640 
  1641 * a generic case distinction tactic `exhaust_tac' which works for all
  1642 datatypes and also for type `nat';
  1643 
  1644 * each datatype comes with a function `size';
  1645 
  1646 * patterns in case expressions allow tuple patterns as arguments to
  1647 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1648 
  1649 * primrec now also works with type nat;
  1650 
  1651 * recdef: a new declaration form, allows general recursive functions to be
  1652 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1653 
  1654 * the constant for negation has been renamed from "not" to "Not" to
  1655 harmonize with FOL, ZF, LK, etc.;
  1656 
  1657 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1658 infinite lists;
  1659 
  1660 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1661 
  1662 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1663 problems in commutative rings, using axiomatic type classes for + and *;
  1664 
  1665 * more examples in HOL/MiniML and HOL/Auth;
  1666 
  1667 * more default rewrite rules for quantifiers, union/intersection;
  1668 
  1669 * a new constant `arbitrary == @x.False';
  1670 
  1671 * HOLCF/IOA replaces old HOL/IOA;
  1672 
  1673 * HOLCF changes: derived all rules and arities
  1674   + axiomatic type classes instead of classes
  1675   + typedef instead of faking type definitions
  1676   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1677   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1678   + eliminated the types void, one, tr
  1679   + use unit lift and bool lift (with translations) instead of one and tr
  1680   + eliminated blift from Lift3.thy (use Def instead of blift)
  1681   all eliminated rules are derived as theorems --> no visible changes ;
  1682 
  1683 
  1684 *** ZF ***
  1685 
  1686 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1687 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1688 as ZF_cs addSIs [equalityI];
  1689 
  1690 
  1691 
  1692 New in Isabelle94-7 (November 96)
  1693 ---------------------------------
  1694 
  1695 * allowing negative levels (as offsets) in prlev and choplev;
  1696 
  1697 * super-linear speedup for large simplifications;
  1698 
  1699 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1700 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1701 FAIL); can suppress it using the command Delsimps (ex_simps @
  1702 all_simps); De Morgan laws are also now included, by default;
  1703 
  1704 * improved printing of ==>  :  ~:
  1705 
  1706 * new object-logic "Sequents" adds linear logic, while replacing LK
  1707 and Modal (thanks to Sara Kalvala);
  1708 
  1709 * HOL/Auth: correctness proofs for authentication protocols;
  1710 
  1711 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1712 examples on HOL/Auth);
  1713 
  1714 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1715 the rewriter and classical reasoner simultaneously;
  1716 
  1717 * function uresult no longer returns theorems in "standard" format;
  1718 regain previous version by: val uresult = standard o uresult;
  1719 
  1720 
  1721 
  1722 New in Isabelle94-6
  1723 -------------------
  1724 
  1725 * oracles -- these establish an interface between Isabelle and trusted
  1726 external reasoners, which may deliver results as theorems;
  1727 
  1728 * proof objects (in particular record all uses of oracles);
  1729 
  1730 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1731 
  1732 * "constdefs" section in theory files;
  1733 
  1734 * "primrec" section (HOL) no longer requires names;
  1735 
  1736 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1737 
  1738 
  1739 
  1740 New in Isabelle94-5
  1741 -------------------
  1742 
  1743 * reduced space requirements;
  1744 
  1745 * automatic HTML generation from theories;
  1746 
  1747 * theory files no longer require "..." (quotes) around most types;
  1748 
  1749 * new examples, including two proofs of the Church-Rosser theorem;
  1750 
  1751 * non-curried (1994) version of HOL is no longer distributed;
  1752 
  1753 
  1754 
  1755 New in Isabelle94-4
  1756 -------------------
  1757 
  1758 * greatly reduced space requirements;
  1759 
  1760 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1761 
  1762 * searchable theorem database (see the section "Retrieving theorems" on
  1763 page 8 of the Reference Manual);
  1764 
  1765 * new examples, including Grabczewski's monumental case study of the
  1766 Axiom of Choice;
  1767 
  1768 * The previous version of HOL renamed to Old_HOL;
  1769 
  1770 * The new version of HOL (previously called CHOL) uses a curried syntax
  1771 for functions.  Application looks like f a b instead of f(a,b);
  1772 
  1773 * Mutually recursive inductive definitions finally work in HOL;
  1774 
  1775 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1776 translates to the operator "split";
  1777 
  1778 
  1779 
  1780 New in Isabelle94-3
  1781 -------------------
  1782 
  1783 * new infix operator, addss, allowing the classical reasoner to
  1784 perform simplification at each step of its search.  Example:
  1785         fast_tac (cs addss ss)
  1786 
  1787 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1788 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1789 look like (a,b) instead of <a,b>;
  1790 
  1791 * PLEASE NOTE: CHOL will eventually replace HOL!
  1792 
  1793 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1794 It translates to the operator "split".  A new theory of integers is available;
  1795 
  1796 * In ZF, integer numerals now denote two's-complement binary integers.
  1797 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1798 
  1799 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1800 of the Axiom of Choice;
  1801 
  1802 
  1803 
  1804 New in Isabelle94-2
  1805 -------------------
  1806 
  1807 * Significantly faster resolution;
  1808 
  1809 * the different sections in a .thy file can now be mixed and repeated
  1810 freely;
  1811 
  1812 * Database of theorems for FOL, HOL and ZF.  New
  1813 commands including qed, qed_goal and bind_thm store theorems in the database.
  1814 
  1815 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1816 a given theory (thms_of), or find out what theory a theorem was proved in
  1817 (theory_of_thm);
  1818 
  1819 * Bugs fixed in the inductive definition and datatype packages;
  1820 
  1821 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1822 and HOL_dup_cs obsolete;
  1823 
  1824 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1825 have been removed;
  1826 
  1827 * Simpler definition of function space in ZF;
  1828 
  1829 * new results about cardinal and ordinal arithmetic in ZF;
  1830 
  1831 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1832 types;
  1833 
  1834 
  1835 $Id$