NEWS
author paulson
Tue Jul 03 15:40:25 2001 +0200 (2001-07-03)
changeset 11397 0427e3c88062
parent 11361 879e53d92f51
child 11437 2338bce575ae
permissions -rw-r--r--
GroupTheory
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 * print modes "type_brackets" and "no_type_brackets" control output of nested
     5 => (types); the default behaviour is "brackets";
     6 
     7 * Classical reasoner: renamed addaltern to addafter, addSaltern to addSafter
     8 
     9 * HOL: introduced f^n = f o ... o f
    10   WARNING: due to the limits of Isabelle's type classes, ^ on functions and
    11   relations has too general a domain, namely ('a * 'b)set and 'a => 'b.
    12   This means that it may be necessary to attach explicit type constraints.
    13 
    14 * HOL: added safe wrapper "split_conv_tac" to claset. EXISTING PROOFS MAY FAIL
    15 
    16 * HOL: made split_all_tac safe. EXISTING PROOFS MAY FAIL OR LOOP, so in this
    17   (rare) case use   delSWrapper "split_all_tac" addSbefore 
    18                     ("unsafe_split_all_tac", unsafe_split_all_tac)
    19 
    20 * HOL/GroupTheory: group theory examples including Sylow's theorem, by Florian
    21   Kammueller;
    22 
    23 * ZF: the integer library now covers quotients and remainders, with many laws
    24 relating division to addition, multiplication, etc.;
    25 
    26 
    27 New in Isabelle99-2 (February 2001)
    28 -----------------------------------
    29 
    30 *** Overview of INCOMPATIBILITIES ***
    31 
    32 * HOL: please note that theories in the Library and elsewhere often use the
    33 new-style (Isar) format; to refer to their theorems in an ML script you must
    34 bind them to ML identifers by e.g.	val thm_name = thm "thm_name";
    35 
    36 * HOL: inductive package no longer splits induction rule aggressively,
    37 but only as far as specified by the introductions given; the old
    38 format may be recovered via ML function complete_split_rule or attribute
    39 'split_rule (complete)';
    40 
    41 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
    42 gfp_Tarski to gfp_unfold;
    43 
    44 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
    45 
    46 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
    47 relation); infix "^^" has been renamed "``"; infix "``" has been
    48 renamed "`"; "univalent" has been renamed "single_valued";
    49 
    50 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
    51 operation;
    52 
    53 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
    54 
    55 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
    56 
    57 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
    58 consequence, it is no longer monotonic wrt. the local goal context
    59 (which is now passed through the inductive cases);
    60 
    61 * Document preparation: renamed standard symbols \<ll> to \<lless> and
    62 \<gg> to \<ggreater>;
    63 
    64 
    65 *** Document preparation ***
    66 
    67 * \isabellestyle{NAME} selects version of Isabelle output (currently
    68 available: are "it" for near math-mode best-style output, "sl" for
    69 slanted text style, and "tt" for plain type-writer; if no
    70 \isabellestyle command is given, output is according to slanted
    71 type-writer);
    72 
    73 * support sub/super scripts (for single symbols only), input syntax is
    74 like this: "A\<^sup>*" or "A\<^sup>\<star>";
    75 
    76 * some more standard symbols; see Appendix A of the system manual for
    77 the complete list of symbols defined in isabellesym.sty;
    78 
    79 * improved isabelle style files; more abstract symbol implementation
    80 (should now use \isamath{...} and \isatext{...} in custom symbol
    81 definitions);
    82 
    83 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
    84 state; Note that presentation of goal states does not conform to
    85 actual human-readable proof documents.  Please do not include goal
    86 states into document output unless you really know what you are doing!
    87 
    88 * proper indentation of antiquoted output with proportional LaTeX
    89 fonts;
    90 
    91 * no_document ML operator temporarily disables LaTeX document
    92 generation;
    93 
    94 * isatool unsymbolize tunes sources for plain ASCII communication;
    95 
    96 
    97 *** Isar ***
    98 
    99 * Pure: Isar now suffers initial goal statements to contain unbound
   100 schematic variables (this does not conform to actual readable proof
   101 documents, due to unpredictable outcome and non-compositional proof
   102 checking); users who know what they are doing may use schematic goals
   103 for Prolog-style synthesis of proven results;
   104 
   105 * Pure: assumption method (an implicit finishing) now handles actual
   106 rules as well;
   107 
   108 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   109 initial goal, declare "that" only as Pure intro (only for single
   110 steps); the "that" rule assumption may now be involved in implicit
   111 finishing, thus ".." becomes a feasible for trivial obtains;
   112 
   113 * Pure: default proof step now includes 'intro_classes'; thus trivial
   114 instance proofs may be performed by "..";
   115 
   116 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   117 statements as well;
   118 
   119 * Pure: more robust selection of calculational rules;
   120 
   121 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   122 rule (as well as the assumption rule);
   123 
   124 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   125 lemmas, using the graph browser tool;
   126 
   127 * Pure: predict failure of "show" in interactive mode;
   128 
   129 * Pure: 'thms_containing' now takes actual terms as arguments;
   130 
   131 * HOL: improved method 'induct' --- now handles non-atomic goals
   132 (potential INCOMPATIBILITY); tuned error handling;
   133 
   134 * HOL: cases and induct rules now provide explicit hints about the
   135 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   136 any remaining facts are inserted into the goal verbatim;
   137 
   138 * HOL: local contexts (aka cases) may now contain term bindings as
   139 well; the 'cases' and 'induct' methods new provide a ?case binding for
   140 the result to be shown in each case;
   141 
   142 * HOL: added 'recdef_tc' command;
   143 
   144 * isatool convert assists in eliminating legacy ML scripts;
   145 
   146 
   147 *** HOL ***
   148 
   149 * HOL/Library: a collection of generic theories to be used together
   150 with main HOL; the theory loader path already includes this directory
   151 by default; the following existing theories have been moved here:
   152 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   153 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   154 
   155 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   156 modelling and verification task performed in Isabelle/HOL +
   157 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   158 
   159 * HOL/Algebra: special summation operator SUM no longer exists, it has
   160 been replaced by setsum; infix 'assoc' now has priority 50 (like
   161 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   162 'domain', this makes the theory consistent with mathematical
   163 literature;
   164 
   165 * HOL basics: added overloaded operations "inverse" and "divide"
   166 (infix "/"), syntax for generic "abs" operation, generic summation
   167 operator \<Sum>;
   168 
   169 * HOL/typedef: simplified package, provide more useful rules (see also
   170 HOL/subset.thy);
   171 
   172 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   173 now expressed as a proper nested rule (old-style tactic scripts may
   174 require atomize_strip_tac to cope with non-atomic premises);
   175 
   176 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   177 to "split_conv" (old name still available for compatibility);
   178 
   179 * HOL: improved concrete syntax for strings (e.g. allows translation
   180 rules with string literals);
   181 
   182 * HOL-Hyperreal: a new target, extending HOL-Real with the hyperreals
   183 and Fleuriot's mechanization of analysis;
   184 
   185 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   186 
   187 
   188 *** CTT ***
   189 
   190 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   191 "lam" is displayed as TWO lambda-symbols
   192 
   193 * CTT: theory Main now available, containing everything (that is, Bool
   194 and Arith);
   195 
   196 
   197 *** General ***
   198 
   199 * Pure: the Simplifier has been implemented properly as a derived rule
   200 outside of the actual kernel (at last!); the overall performance
   201 penalty in practical applications is about 50%, while reliability of
   202 the Isabelle inference kernel has been greatly improved;
   203 
   204 * print modes "brackets" and "no_brackets" control output of nested =>
   205 (types) and ==> (props); the default behaviour is "brackets";
   206 
   207 * Provers: fast_tac (and friends) now handle actual object-logic rules
   208 as assumptions as well;
   209 
   210 * system: support Poly/ML 4.0;
   211 
   212 * system: isatool install handles KDE version 1 or 2;
   213 
   214 
   215 
   216 New in Isabelle99-1 (October 2000)
   217 ----------------------------------
   218 
   219 *** Overview of INCOMPATIBILITIES ***
   220 
   221 * HOL: simplification of natural numbers is much changed; to partly
   222 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   223 issue the following ML commands:
   224 
   225   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   226   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   227 
   228 * HOL: simplification no longer dives into case-expressions; this is
   229 controlled by "t.weak_case_cong" for each datatype t;
   230 
   231 * HOL: nat_less_induct renamed to less_induct;
   232 
   233 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   234 fixsome to patch .thy and .ML sources automatically;
   235 
   236   select_equality  -> some_equality
   237   select_eq_Ex     -> some_eq_ex
   238   selectI2EX       -> someI2_ex
   239   selectI2         -> someI2
   240   selectI          -> someI
   241   select1_equality -> some1_equality
   242   Eps_sym_eq       -> some_sym_eq_trivial
   243   Eps_eq           -> some_eq_trivial
   244 
   245 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   246 
   247 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   248 instead);
   249 
   250 * HOL: the recursion equations generated by 'recdef' are now called
   251 f.simps instead of f.rules;
   252 
   253 * HOL: qed_spec_mp now also handles bounded ALL as well;
   254 
   255 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   256 sometimes be needed;
   257 
   258 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   259 
   260 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   261 
   262 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   263 product is now "<*>" instead of "Times"; the lexicographic product is
   264 now "<*lex*>" instead of "**";
   265 
   266 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   267 of main HOL, but was unused); better use HOL's datatype package;
   268 
   269 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   270 the old syntax may be recovered as follows:
   271 
   272   syntax (symbols)
   273     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   274       (infixl "\\<oplus>" 100)
   275 
   276 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   277 
   278 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   279 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   280 internally;
   281 
   282 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   283 changed from A/r to A//r;
   284 
   285 * ZF: new treatment of arithmetic (nat & int) may break some old
   286 proofs;
   287 
   288 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   289 rulify -> rule_format, elimify -> elim_format, ...);
   290 
   291 * Isar/Provers: intro/elim/dest attributes changed; renamed
   292 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   293 should have to change intro!! to intro? only); replaced "delrule" by
   294 "rule del";
   295 
   296 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   297 
   298 * Provers: strengthened force_tac by using new first_best_tac;
   299 
   300 * LaTeX document preparation: several changes of isabelle.sty (see
   301 lib/texinputs);
   302 
   303 
   304 *** Document preparation ***
   305 
   306 * formal comments (text blocks etc.) in new-style theories may now
   307 contain antiquotations of thm/prop/term/typ/text to be presented
   308 according to latex print mode; concrete syntax is like this:
   309 @{term[show_types] "f(x) = a + x"};
   310 
   311 * isatool mkdir provides easy setup of Isabelle session directories,
   312 including proper document sources;
   313 
   314 * generated LaTeX sources are now deleted after successful run
   315 (isatool document -c); may retain a copy somewhere else via -D option
   316 of isatool usedir;
   317 
   318 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   319 style files, achieving self-contained LaTeX sources and simplifying
   320 LaTeX debugging;
   321 
   322 * old-style theories now produce (crude) LaTeX output as well;
   323 
   324 * browser info session directories are now self-contained (may be put
   325 on WWW server seperately); improved graphs of nested sessions; removed
   326 graph for 'all sessions';
   327 
   328 * several improvements in isabelle style files; \isabellestyle{it}
   329 produces fake math mode output; \isamarkupheader is now \section by
   330 default; see lib/texinputs/isabelle.sty etc.;
   331 
   332 
   333 *** Isar ***
   334 
   335 * Isar/Pure: local results and corresponding term bindings are now
   336 subject to Hindley-Milner polymorphism (similar to ML); this
   337 accommodates incremental type-inference very nicely;
   338 
   339 * Isar/Pure: new derived language element 'obtain' supports
   340 generalized existence reasoning;
   341 
   342 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   343 support accumulation of results, without applying any rules yet;
   344 useful to collect intermediate results without explicit name
   345 references, and for use with transitivity rules with more than 2
   346 premises;
   347 
   348 * Isar/Pure: scalable support for case-analysis type proofs: new
   349 'case' language element refers to local contexts symbolically, as
   350 produced by certain proof methods; internally, case names are attached
   351 to theorems as "tags";
   352 
   353 * Isar/Pure: theory command 'hide' removes declarations from
   354 class/type/const name spaces;
   355 
   356 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   357 indicate potential overloading;
   358 
   359 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   360 
   361 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   362 "{a,b,c}" instead of {a,b,c};
   363 
   364 * Isar/Pure now provides its own version of intro/elim/dest
   365 attributes; useful for building new logics, but beware of confusion
   366 with the version in Provers/classical;
   367 
   368 * Isar/Pure: the local context of (non-atomic) goals is provided via
   369 case name 'antecedent';
   370 
   371 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   372 to the current context is now done automatically);
   373 
   374 * Isar/Pure: theory command 'method_setup' provides a simple interface
   375 for definining proof methods in ML;
   376 
   377 * Isar/Provers: intro/elim/dest attributes changed; renamed
   378 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   379 most cases, one should have to change intro!! to intro? only);
   380 replaced "delrule" by "rule del";
   381 
   382 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   383 'symmetric' attribute (the latter supercedes [RS sym]);
   384 
   385 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   386 method modifier); 'simp' method: 'only:' modifier removes loopers as
   387 well (including splits);
   388 
   389 * Isar/Provers: Simplifier and Classical methods now support all kind
   390 of modifiers used in the past, including 'cong', 'iff', etc.
   391 
   392 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   393 of Simplifier and Classical reasoner);
   394 
   395 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   396 now support named cases; major packages (inductive, datatype, primrec,
   397 recdef) support case names and properly name parameters;
   398 
   399 * Isar/HOL: new transitivity rules for substitution in inequalities --
   400 monotonicity conditions are extracted to be proven at end of
   401 calculations;
   402 
   403 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   404 method anyway;
   405 
   406 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   407 split_if split_if_asm; datatype package provides theorems foo.splits =
   408 foo.split foo.split_asm for each datatype;
   409 
   410 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   411 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   412 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   413 use "(cases (simplified))" method in proper proof texts);
   414 
   415 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   416 
   417 * Isar: names of theorems etc. may be natural numbers as well;
   418 
   419 * Isar: 'pr' command: optional arguments for goals_limit and
   420 ProofContext.prems_limit; no longer prints theory contexts, but only
   421 proof states;
   422 
   423 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   424 additional print modes to be specified; e.g. "pr(latex)" will print
   425 proof state according to the Isabelle LaTeX style;
   426 
   427 * Isar: improved support for emulating tactic scripts, including proof
   428 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   429 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   430 (for HOL datatypes);
   431 
   432 * Isar: simplified (more robust) goal selection of proof methods: 1st
   433 goal, all goals, or explicit goal specifier (tactic emulation); thus
   434 'proof method scripts' have to be in depth-first order;
   435 
   436 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   437 
   438 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   439 should instead use individual commands for printing items
   440 (print_commands, print_methods etc.);
   441 
   442 * Isar: added 'nothing' --- the empty list of theorems;
   443 
   444 
   445 *** HOL ***
   446 
   447 * HOL/MicroJava: formalization of a fragment of Java, together with a
   448 corresponding virtual machine and a specification of its bytecode
   449 verifier and a lightweight bytecode verifier, including proofs of
   450 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   451 Cornelia Pusch (see also the homepage of project Bali at
   452 http://isabelle.in.tum.de/Bali/);
   453 
   454 * HOL/Algebra: new theory of rings and univariate polynomials, by
   455 Clemens Ballarin;
   456 
   457 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   458 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   459 Rasmussen;
   460 
   461 * HOL/Lattice: fundamental concepts of lattice theory and order
   462 structures, including duals, properties of bounds versus algebraic
   463 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   464 Theorem for complete lattices etc.; may also serve as a demonstration
   465 for abstract algebraic reasoning using axiomatic type classes, and
   466 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   467 
   468 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   469 von Oheimb;
   470 
   471 * HOL/IMPP: extension of IMP with local variables and mutually
   472 recursive procedures, by David von Oheimb;
   473 
   474 * HOL/Lambda: converted into new-style theory and document;
   475 
   476 * HOL/ex/Multiquote: example of multiple nested quotations and
   477 anti-quotations -- basically a generalized version of de-Bruijn
   478 representation; very useful in avoiding lifting of operations;
   479 
   480 * HOL/record: added general record equality rule to simpset; fixed
   481 select-update simplification procedure to handle extended records as
   482 well; admit "r" as field name;
   483 
   484 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   485 other numeric types and also as the identity of groups, rings, etc.;
   486 
   487 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   488 Types nat and int belong to this axclass;
   489 
   490 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   491    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   492    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   493   two terms #m*u and #n*u are replaced by #(m+n)*u
   494     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   495   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   496     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   497 
   498 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   499 powerful prover for predicate logic but knows nothing of clasets; see
   500 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   501 
   502 * HOL: new version of "case_tac" subsumes both boolean case split and
   503 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   504 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   505 
   506 * HOL: simplification no longer dives into case-expressions: only the
   507 selector expression is simplified, but not the remaining arms; to
   508 enable full simplification of case-expressions for datatype t, you may
   509 remove t.weak_case_cong from the simpset, either globally (Delcongs
   510 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   511 
   512 * HOL/recdef: the recursion equations generated by 'recdef' for
   513 function 'f' are now called f.simps instead of f.rules; if all
   514 termination conditions are proved automatically, these simplification
   515 rules are added to the simpset, as in primrec; rules may be named
   516 individually as well, resulting in a separate list of theorems for
   517 each equation;
   518 
   519 * HOL/While is a new theory that provides a while-combinator. It
   520 permits the definition of tail-recursive functions without the
   521 provision of a termination measure. The latter is necessary once the
   522 invariant proof rule for while is applied.
   523 
   524 * HOL: new (overloaded) notation for the set of elements below/above
   525 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   526 
   527 * HOL: theorems impI, allI, ballI bound as "strip";
   528 
   529 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   530 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   531 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   532 
   533 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   534 
   535 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   536 main HOL, but was unused);
   537 
   538 * HOL: fewer consts declared as global (e.g. have to refer to
   539 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   540 
   541 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   542 in case of overlap with user translations (e.g. judgements over
   543 tuples); (note that the underlying logical represenation is still
   544 bogus);
   545 
   546 
   547 *** ZF ***
   548 
   549 * ZF: simplification automatically cancels common terms in arithmetic
   550 expressions over nat and int;
   551 
   552 * ZF: new treatment of nat to minimize type-checking: all operators
   553 coerce their operands to a natural number using the function natify,
   554 making the algebraic laws unconditional;
   555 
   556 * ZF: as above, for int: operators coerce their operands to an integer
   557 using the function intify;
   558 
   559 * ZF: the integer library now contains many of the usual laws for the
   560 orderings, including $<=, and monotonicity laws for $+ and $*;
   561 
   562 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
   563 simplification;
   564 
   565 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
   566 to the simplifier and classical reasoner simultaneously;
   567 
   568 
   569 *** General ***
   570 
   571 * Provers: blast_tac now handles actual object-logic rules as
   572 assumptions; note that auto_tac uses blast_tac internally as well;
   573 
   574 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
   575 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
   576 
   577 * Provers: delrules now handles destruct rules as well (no longer need
   578 explicit make_elim);
   579 
   580 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
   581   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   582 use instead the strong form,
   583   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   584 in HOL, FOL and ZF the function cla_make_elim will create such rules
   585 from destruct-rules;
   586 
   587 * Provers: Simplifier.easy_setup provides a fast path to basic
   588 Simplifier setup for new object-logics;
   589 
   590 * Pure: AST translation rules no longer require constant head on LHS;
   591 
   592 * Pure: improved name spaces: ambiguous output is qualified; support
   593 for hiding of names;
   594 
   595 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
   596 XSYMBOL_HOME; no longer need to do manual configuration in most
   597 situations;
   598 
   599 * system: compression of ML heaps images may now be controlled via -c
   600 option of isabelle and isatool usedir (currently only observed by
   601 Poly/ML);
   602 
   603 * system: isatool installfonts may handle X-Symbol fonts as well (very
   604 useful for remote X11);
   605 
   606 * system: provide TAGS file for Isabelle sources;
   607 
   608 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
   609 order;
   610 
   611 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
   612 timing flag supersedes proof_timing and Toplevel.trace;
   613 
   614 * ML: new combinators |>> and |>>> for incremental transformations
   615 with secondary results (e.g. certain theory extensions):
   616 
   617 * ML: PureThy.add_defs gets additional argument to indicate potential
   618 overloading (usually false);
   619 
   620 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
   621 results;
   622 
   623 
   624 
   625 New in Isabelle99 (October 1999)
   626 --------------------------------
   627 
   628 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   629 
   630 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
   631 are no longer simplified.  (This allows the simplifier to unfold recursive
   632 functional programs.)  To restore the old behaviour, declare
   633 
   634     Delcongs [if_weak_cong];
   635 
   636 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
   637 complement;
   638 
   639 * HOL: the predicate "inj" is now defined by translation to "inj_on";
   640 
   641 * HOL/datatype: mutual_induct_tac no longer exists --
   642   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
   643 
   644 * HOL/typedef: fixed type inference for representing set; type
   645 arguments now have to occur explicitly on the rhs as type constraints;
   646 
   647 * ZF: The con_defs part of an inductive definition may no longer refer
   648 to constants declared in the same theory;
   649 
   650 * HOL, ZF: the function mk_cases, generated by the inductive
   651 definition package, has lost an argument.  To simplify its result, it
   652 uses the default simpset instead of a supplied list of theorems.
   653 
   654 * HOL/List: the constructors of type list are now Nil and Cons;
   655 
   656 * Simplifier: the type of the infix ML functions
   657         setSSolver addSSolver setSolver addSolver
   658 is now  simpset * solver -> simpset  where `solver' is a new abstract type
   659 for packaging solvers. A solver is created via
   660         mk_solver: string -> (thm list -> int -> tactic) -> solver
   661 where the string argument is only a comment.
   662 
   663 
   664 *** Proof tools ***
   665 
   666 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
   667 decision procedure for linear arithmetic. Currently it is used for
   668 types `nat', `int', and `real' in HOL (see below); it can, should and
   669 will be instantiated for other types and logics as well.
   670 
   671 * The simplifier now accepts rewrite rules with flexible heads, eg
   672      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
   673   They are applied like any rule with a non-pattern lhs, i.e. by first-order
   674   matching.
   675 
   676 
   677 *** General ***
   678 
   679 * New Isabelle/Isar subsystem provides an alternative to traditional
   680 tactical theorem proving; together with the ProofGeneral/isar user
   681 interface it offers an interactive environment for developing human
   682 readable proof documents (Isar == Intelligible semi-automated
   683 reasoning); for further information see isatool doc isar-ref,
   684 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
   685 
   686 * improved and simplified presentation of theories: better HTML markup
   687 (including colors), graph views in several sizes; isatool usedir now
   688 provides a proper interface for user theories (via -P option); actual
   689 document preparation based on (PDF)LaTeX is available as well (for
   690 new-style theories only); see isatool doc system for more information;
   691 
   692 * native support for Proof General, both for classic Isabelle and
   693 Isabelle/Isar;
   694 
   695 * ML function thm_deps visualizes dependencies of theorems and lemmas,
   696 using the graph browser tool;
   697 
   698 * Isabelle manuals now also available as PDF;
   699 
   700 * theory loader rewritten from scratch (may not be fully
   701 bug-compatible); old loadpath variable has been replaced by show_path,
   702 add_path, del_path, reset_path functions; new operations such as
   703 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
   704 isatool doc ref);
   705 
   706 * improved isatool install: option -k creates KDE application icon,
   707 option -p DIR installs standalone binaries;
   708 
   709 * added ML_PLATFORM setting (useful for cross-platform installations);
   710 more robust handling of platform specific ML images for SML/NJ;
   711 
   712 * the settings environment is now statically scoped, i.e. it is never
   713 created again in sub-processes invoked from isabelle, isatool, or
   714 Isabelle;
   715 
   716 * path element specification '~~' refers to '$ISABELLE_HOME';
   717 
   718 * in locales, the "assumes" and "defines" parts may be omitted if
   719 empty;
   720 
   721 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   722 long arrows);
   723 
   724 * new print_mode "HTML";
   725 
   726 * new flag show_tags controls display of tags of theorems (which are
   727 basically just comments that may be attached by some tools);
   728 
   729 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   730 mode and goal output format:
   731 
   732 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   733 244c244
   734 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   735 ---
   736 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   737 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   738 181c181
   739 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   740 ---
   741 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   742 
   743 * function bind_thms stores lists of theorems (cf. bind_thm);
   744 
   745 * new shorthand tactics ftac, eatac, datac, fatac;
   746 
   747 * qed (and friends) now accept "" as result name; in that case the
   748 theorem is not stored, but proper checks and presentation of the
   749 result still apply;
   750 
   751 * theorem database now also indexes constants "Trueprop", "all",
   752 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   753 
   754 
   755 *** HOL ***
   756 
   757 ** HOL arithmetic **
   758 
   759 * There are now decision procedures for linear arithmetic over nat and
   760 int:
   761 
   762 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   763 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   764 are treated as atomic; subformulae not involving type `nat' or `int'
   765 are ignored; quantified subformulae are ignored unless they are
   766 positive universal or negative existential. The tactic has to be
   767 invoked by hand and can be a little bit slow. In particular, the
   768 running time is exponential in the number of occurrences of `min' and
   769 `max', and `-' on `nat'.
   770 
   771 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   772 (negated) (in)equalities among the premises and the conclusion into
   773 account (i.e. no compound formulae) and does not know about `min' and
   774 `max', and `-' on `nat'. It is fast and is used automatically by the
   775 simplifier.
   776 
   777 NB: At the moment, these decision procedures do not cope with mixed
   778 nat/int formulae where the two parts interact, such as `m < n ==>
   779 int(m) < int(n)'.
   780 
   781 * HOL/Numeral provides a generic theory of numerals (encoded
   782 efficiently as bit strings); setup for types nat/int/real is in place;
   783 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   784 int, existing theories and proof scripts may require a few additional
   785 type constraints;
   786 
   787 * integer division and remainder can now be performed on constant
   788 arguments;
   789 
   790 * many properties of integer multiplication, division and remainder
   791 are now available;
   792 
   793 * An interface to the Stanford Validity Checker (SVC) is available through the
   794 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   795 are proved automatically.  SVC must be installed separately, and its results
   796 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   797 invocation of the underlying oracle).  For SVC see
   798   http://verify.stanford.edu/SVC
   799 
   800 * IsaMakefile: the HOL-Real target now builds an actual image;
   801 
   802 
   803 ** HOL misc **
   804 
   805 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   806 (in Isabelle/Isar) -- by Gertrud Bauer;
   807 
   808 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   809 analysis for assembly languages with subtypes;
   810 
   811 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   812 -- avoids syntactic ambiguities and treats state, transition, and
   813 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   814 changed syntax and (many) tactics;
   815 
   816 * HOL/inductive: Now also handles more general introduction rules such
   817   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
   818   theorems are now maintained within the theory (maintained via the
   819   "mono" attribute);
   820 
   821 * HOL/datatype: Now also handles arbitrarily branching datatypes
   822   (using function types) such as
   823 
   824   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
   825 
   826 * HOL/record: record_simproc (part of the default simpset) takes care
   827 of selectors applied to updated records; record_split_tac is no longer
   828 part of the default claset; update_defs may now be removed from the
   829 simpset in many cases; COMPATIBILITY: old behavior achieved by
   830 
   831   claset_ref () := claset() addSWrapper record_split_wrapper;
   832   Delsimprocs [record_simproc]
   833 
   834 * HOL/typedef: fixed type inference for representing set; type
   835 arguments now have to occur explicitly on the rhs as type constraints;
   836 
   837 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
   838 names rather than an ML expression;
   839 
   840 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
   841 supplied later.  Program schemes can be defined, such as
   842     "While B C s = (if B s then While B C (C s) else s)"
   843 where the well-founded relation can be chosen after B and C have been given.
   844 
   845 * HOL/List: the constructors of type list are now Nil and Cons;
   846 INCOMPATIBILITY: while [] and infix # syntax is still there, of
   847 course, ML tools referring to List.list.op # etc. have to be adapted;
   848 
   849 * HOL_quantifiers flag superseded by "HOL" print mode, which is
   850 disabled by default; run isabelle with option -m HOL to get back to
   851 the original Gordon/HOL-style output;
   852 
   853 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
   854 ALL x<=y. P, EX x<y. P, EX x<=y. P;
   855 
   856 * HOL basic syntax simplified (more orthogonal): all variants of
   857 All/Ex now support plain / symbolic / HOL notation; plain syntax for
   858 Eps operator is provided as well: "SOME x. P[x]";
   859 
   860 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
   861 
   862 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
   863 thus available for user theories;
   864 
   865 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
   866 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
   867 time;
   868 
   869 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
   870 several times and then mp;
   871 
   872 
   873 *** LK ***
   874 
   875 * the notation <<...>> is now available as a notation for sequences of
   876 formulas;
   877 
   878 * the simplifier is now installed
   879 
   880 * the axiom system has been generalized (thanks to Soren Heilmann)
   881 
   882 * the classical reasoner now has a default rule database
   883 
   884 
   885 *** ZF ***
   886 
   887 * new primrec section allows primitive recursive functions to be given
   888 directly (as in HOL) over datatypes and the natural numbers;
   889 
   890 * new tactics induct_tac and exhaust_tac for induction (or case
   891 analysis) over datatypes and the natural numbers;
   892 
   893 * the datatype declaration of type T now defines the recursor T_rec;
   894 
   895 * simplification automatically does freeness reasoning for datatype
   896 constructors;
   897 
   898 * automatic type-inference, with AddTCs command to insert new
   899 type-checking rules;
   900 
   901 * datatype introduction rules are now added as Safe Introduction rules
   902 to the claset;
   903 
   904 * the syntax "if P then x else y" is now available in addition to
   905 if(P,x,y);
   906 
   907 
   908 *** Internal programming interfaces ***
   909 
   910 * tuned simplifier trace output; new flag debug_simp;
   911 
   912 * structures Vartab / Termtab (instances of TableFun) offer efficient
   913 tables indexed by indexname_ord / term_ord (compatible with aconv);
   914 
   915 * AxClass.axclass_tac lost the theory argument;
   916 
   917 * tuned current_goals_markers semantics: begin / end goal avoids
   918 printing empty lines;
   919 
   920 * removed prs and prs_fn hook, which was broken because it did not
   921 include \n in its semantics, forcing writeln to add one
   922 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
   923 string -> unit if you really want to output text without newline;
   924 
   925 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
   926 plain output, interface builders may have to enable 'isabelle_font'
   927 mode to get Isabelle font glyphs as before;
   928 
   929 * refined token_translation interface; INCOMPATIBILITY: output length
   930 now of type real instead of int;
   931 
   932 * theory loader actions may be traced via new ThyInfo.add_hook
   933 interface (see src/Pure/Thy/thy_info.ML); example application: keep
   934 your own database of information attached to *whole* theories -- as
   935 opposed to intra-theory data slots offered via TheoryDataFun;
   936 
   937 * proper handling of dangling sort hypotheses (at last!);
   938 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
   939 extra sort hypotheses that can be witnessed from the type signature;
   940 the force_strip_shyps flag is gone, any remaining shyps are simply
   941 left in the theorem (with a warning issued by strip_shyps_warning);
   942 
   943 
   944 
   945 New in Isabelle98-1 (October 1998)
   946 ----------------------------------
   947 
   948 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   949 
   950 * several changes of automated proof tools;
   951 
   952 * HOL: major changes to the inductive and datatype packages, including
   953 some minor incompatibilities of theory syntax;
   954 
   955 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
   956 called `inj_on';
   957 
   958 * HOL: removed duplicate thms in Arith:
   959   less_imp_add_less  should be replaced by  trans_less_add1
   960   le_imp_add_le      should be replaced by  trans_le_add1
   961 
   962 * HOL: unary minus is now overloaded (new type constraints may be
   963 required);
   964 
   965 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
   966 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
   967 now taken as an integer constant.
   968 
   969 * Pure: ML function 'theory_of' renamed to 'theory';
   970 
   971 
   972 *** Proof tools ***
   973 
   974 * Simplifier:
   975   1. Asm_full_simp_tac is now more aggressive.
   976      1. It will sometimes reorient premises if that increases their power to
   977         simplify.
   978      2. It does no longer proceed strictly from left to right but may also
   979         rotate premises to achieve further simplification.
   980      For compatibility reasons there is now Asm_lr_simp_tac which is like the
   981      old Asm_full_simp_tac in that it does not rotate premises.
   982   2. The simplifier now knows a little bit about nat-arithmetic.
   983 
   984 * Classical reasoner: wrapper mechanism for the classical reasoner now
   985 allows for selected deletion of wrappers, by introduction of names for
   986 wrapper functionals.  This implies that addbefore, addSbefore,
   987 addaltern, and addSaltern now take a pair (name, tactic) as argument,
   988 and that adding two tactics with the same name overwrites the first
   989 one (emitting a warning).
   990   type wrapper = (int -> tactic) -> (int -> tactic)
   991   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
   992   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
   993   delWrapper, delSWrapper: claset *  string            -> claset
   994   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
   995 
   996 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
   997 semantics; addbefore now affects only the unsafe part of step_tac
   998 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
   999 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1000 by Force_tac;
  1001 
  1002 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1003 compWrapper; added safe wrapper (and access functions for it);
  1004 
  1005 * HOL/split_all_tac is now much faster and fails if there is nothing
  1006 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1007 and the names of the automatically generated variables have changed.
  1008 split_all_tac has moved within claset() from unsafe wrappers to safe
  1009 wrappers, which means that !!-bound variables are split much more
  1010 aggressively, and safe_tac and clarify_tac now split such variables.
  1011 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1012 Note: the same holds for record_split_tac, which does the job of
  1013 split_all_tac for record fields.
  1014 
  1015 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1016 permanently to the default simpset using Addsplits just like
  1017 Addsimps. They can be removed via Delsplits just like
  1018 Delsimps. Lower-case versions are also available.
  1019 
  1020 * HOL/Simplifier: The rule split_if is now part of the default
  1021 simpset. This means that the simplifier will eliminate all occurrences
  1022 of if-then-else in the conclusion of a goal. To prevent this, you can
  1023 either remove split_if completely from the default simpset by
  1024 `Delsplits [split_if]' or remove it in a specific call of the
  1025 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1026 other case splitting rules to/from the default simpset: every datatype
  1027 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1028 t is the name of the datatype).
  1029 
  1030 * Classical reasoner / Simplifier combination: new force_tac (and
  1031 derivatives Force_tac, force) combines rewriting and classical
  1032 reasoning (and whatever other tools) similarly to auto_tac, but is
  1033 aimed to solve the given subgoal completely.
  1034 
  1035 
  1036 *** General ***
  1037 
  1038 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1039 and `goalw': the theory is no longer needed as an explicit argument -
  1040 the current theory context is used; assumptions are no longer returned
  1041 at the ML-level unless one of them starts with ==> or !!; it is
  1042 recommended to convert to these new commands using isatool fixgoal
  1043 (backup your sources first!);
  1044 
  1045 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1046 the current theory context, and 'theory' to lookup stored theories;
  1047 
  1048 * new theory section 'locale' for declaring constants, assumptions and
  1049 definitions that have local scope;
  1050 
  1051 * new theory section 'nonterminals' for purely syntactic types;
  1052 
  1053 * new theory section 'setup' for generic ML setup functions
  1054 (e.g. package initialization);
  1055 
  1056 * the distribution now includes Isabelle icons: see
  1057 lib/logo/isabelle-{small,tiny}.xpm;
  1058 
  1059 * isatool install - install binaries with absolute references to
  1060 ISABELLE_HOME/bin;
  1061 
  1062 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1063 
  1064 * print mode 'emacs' reserved for Isamode;
  1065 
  1066 * support multiple print (ast) translations per constant name;
  1067 
  1068 * theorems involving oracles are now printed with a suffixed [!];
  1069 
  1070 
  1071 *** HOL ***
  1072 
  1073 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1074 
  1075 * HOL/inductive package reorganized and improved: now supports mutual
  1076 definitions such as
  1077 
  1078   inductive EVEN ODD
  1079     intrs
  1080       null "0 : EVEN"
  1081       oddI "n : EVEN ==> Suc n : ODD"
  1082       evenI "n : ODD ==> Suc n : EVEN"
  1083 
  1084 new theorem list "elims" contains an elimination rule for each of the
  1085 recursive sets; inductive definitions now handle disjunctive premises
  1086 correctly (also ZF);
  1087 
  1088 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1089 "mutual_induct" no longer exists - the induction rule is always
  1090 contained in "induct";
  1091 
  1092 
  1093 * HOL/datatype package re-implemented and greatly improved: now
  1094 supports mutually recursive datatypes such as
  1095 
  1096   datatype
  1097     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1098             | SUM ('a aexp) ('a aexp)
  1099             | DIFF ('a aexp) ('a aexp)
  1100             | NUM 'a
  1101   and
  1102     'a bexp = LESS ('a aexp) ('a aexp)
  1103             | AND ('a bexp) ('a bexp)
  1104             | OR ('a bexp) ('a bexp)
  1105 
  1106 as well as indirectly recursive datatypes such as
  1107 
  1108   datatype
  1109     ('a, 'b) term = Var 'a
  1110                   | App 'b ((('a, 'b) term) list)
  1111 
  1112 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1113 induction on mutually / indirectly recursive datatypes.
  1114 
  1115 Primrec equations are now stored in theory and can be accessed via
  1116 <function_name>.simps.
  1117 
  1118 INCOMPATIBILITIES:
  1119 
  1120   - Theories using datatypes must now have theory Datatype as an
  1121     ancestor.
  1122   - The specific <typename>.induct_tac no longer exists - use the
  1123     generic induct_tac instead.
  1124   - natE has been renamed to nat.exhaust - use exhaust_tac
  1125     instead of res_inst_tac ... natE. Note that the variable
  1126     names in nat.exhaust differ from the names in natE, this
  1127     may cause some "fragile" proofs to fail.
  1128   - The theorems split_<typename>_case and split_<typename>_case_asm
  1129     have been renamed to <typename>.split and <typename>.split_asm.
  1130   - Since default sorts of type variables are now handled correctly,
  1131     some datatype definitions may have to be annotated with explicit
  1132     sort constraints.
  1133   - Primrec definitions no longer require function name and type
  1134     of recursive argument.
  1135 
  1136 Consider using isatool fixdatatype to adapt your theories and proof
  1137 scripts to the new package (backup your sources first!).
  1138 
  1139 
  1140 * HOL/record package: considerably improved implementation; now
  1141 includes concrete syntax for record types, terms, updates; theorems
  1142 for surjective pairing and splitting !!-bound record variables; proof
  1143 support is as follows:
  1144 
  1145   1) standard conversions (selectors or updates applied to record
  1146 constructor terms) are part of the standard simpset;
  1147 
  1148   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1149 made part of standard simpset and claset via addIffs;
  1150 
  1151   3) a tactic for record field splitting (record_split_tac) is part of
  1152 the standard claset (addSWrapper);
  1153 
  1154 To get a better idea about these rules you may retrieve them via
  1155 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1156 the name of your record type.
  1157 
  1158 The split tactic 3) conceptually simplifies by the following rule:
  1159 
  1160   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1161 
  1162 Thus any record variable that is bound by meta-all will automatically
  1163 blow up into some record constructor term, consequently the
  1164 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1165 solve record problems automatically.
  1166 
  1167 
  1168 * reorganized the main HOL image: HOL/Integ and String loaded by
  1169 default; theory Main includes everything;
  1170 
  1171 * automatic simplification of integer sums and comparisons, using cancellation;
  1172 
  1173 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1174 
  1175 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1176 
  1177 * many new identities for unions, intersections, set difference, etc.;
  1178 
  1179 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1180 called split_if, split_split, split_sum_case and split_nat_case (to go
  1181 with add/delsplits);
  1182 
  1183 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1184 (?x::unit) = (); this is made part of the default simpset, which COULD
  1185 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1186 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1187 unit_abs_eta_conv is added in order to counter the effect of
  1188 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1189 %u.f();
  1190 
  1191 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1192 makes more sense);
  1193 
  1194 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1195   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1196   disjointness reasoning but breaking a few old proofs.
  1197 
  1198 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1199 to 'converse' from 'inverse' (for compatibility with ZF and some
  1200 literature);
  1201 
  1202 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1203 the well-founded relation;
  1204 
  1205 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1206     Compl A.  The "Compl" syntax remains available as input syntax for this
  1207     release ONLY.
  1208 
  1209 * HOL/Update: new theory of function updates:
  1210     f(a:=b) == %x. if x=a then b else f x
  1211 may also be iterated as in f(a:=b,c:=d,...);
  1212 
  1213 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1214 
  1215 * HOL/List:
  1216   - new function list_update written xs[i:=v] that updates the i-th
  1217     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1218   - new function `upt' written [i..j(] which generates the list
  1219     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1220     bound write [i..j], which is a shorthand for [i..j+1(].
  1221   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1222 
  1223 * HOL/Arith:
  1224   - removed 'pred' (predecessor) function;
  1225   - generalized some theorems about n-1;
  1226   - many new laws about "div" and "mod";
  1227   - new laws about greatest common divisors (see theory ex/Primes);
  1228 
  1229 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1230 instead of "inverse";
  1231 
  1232 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1233   of the multiset ordering;
  1234 
  1235 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1236   (not included by default);
  1237 
  1238 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1239 
  1240 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1241   programs, i.e. different program variables may have different types.
  1242 
  1243 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1244   [previously, this check worked only if the rewrite rule was unconditional]
  1245   Now rew can involve either definitions or equalities (either == or =).
  1246 
  1247 
  1248 *** ZF ***
  1249 
  1250 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1251   only the theorems proved on ZF.ML;
  1252 
  1253 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1254   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1255   disjointness reasoning but breaking a few old proofs.
  1256 
  1257 * ZF/Update: new theory of function updates
  1258     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1259   may also be iterated as in f(a:=b,c:=d,...);
  1260 
  1261 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  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 * case_tac provided for compatibility with HOL
  1268     (like the old excluded_middle_tac, but with subgoals swapped)
  1269 
  1270 
  1271 *** Internal programming interfaces ***
  1272 
  1273 * Pure: several new basic modules made available for general use, see
  1274 also src/Pure/README;
  1275 
  1276 * improved the theory data mechanism to support encapsulation (data
  1277 kind name replaced by private Object.kind, acting as authorization
  1278 key); new type-safe user interface via functor TheoryDataFun; generic
  1279 print_data function becomes basically useless;
  1280 
  1281 * removed global_names compatibility flag -- all theory declarations
  1282 are qualified by default;
  1283 
  1284 * module Pure/Syntax now offers quote / antiquote translation
  1285 functions (useful for Hoare logic etc. with implicit dependencies);
  1286 see HOL/ex/Antiquote for an example use;
  1287 
  1288 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1289 cterm -> thm;
  1290 
  1291 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1292 subgoal;
  1293 
  1294 * Display.print_goals function moved to Locale.print_goals;
  1295 
  1296 * standard print function for goals supports current_goals_markers
  1297 variable for marking begin of proof, end of proof, start of goal; the
  1298 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1299 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1300 for example;
  1301 
  1302 
  1303 
  1304 New in Isabelle98 (January 1998)
  1305 --------------------------------
  1306 
  1307 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1308 
  1309 * changed lexical syntax of terms / types: dots made part of long
  1310 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1311 
  1312 * simpset (and claset) reference variable replaced by functions
  1313 simpset / simpset_ref;
  1314 
  1315 * no longer supports theory aliases (via merge) and non-trivial
  1316 implicit merge of thms' signatures;
  1317 
  1318 * most internal names of constants changed due to qualified names;
  1319 
  1320 * changed Pure/Sequence interface (see Pure/seq.ML);
  1321 
  1322 
  1323 *** General Changes ***
  1324 
  1325 * hierachically structured name spaces (for consts, types, axms, thms
  1326 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1327 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1328 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1329 long_names for fully qualified output names; NOTE: ML programs
  1330 (special tactics, packages etc.) referring to internal names may have
  1331 to be adapted to cope with fully qualified names; in case of severe
  1332 backward campatibility problems try setting 'global_names' at compile
  1333 time to have enrything declared within a flat name space; one may also
  1334 fine tune name declarations in theories via the 'global' and 'local'
  1335 section;
  1336 
  1337 * reimplemented the implicit simpset and claset using the new anytype
  1338 data filed in signatures; references simpset:simpset ref etc. are
  1339 replaced by functions simpset:unit->simpset and
  1340 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1341 to patch your ML files accordingly;
  1342 
  1343 * HTML output now includes theory graph data for display with Java
  1344 applet or isatool browser; data generated automatically via isatool
  1345 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1346 
  1347 * defs may now be conditional; improved rewrite_goals_tac to handle
  1348 conditional equations;
  1349 
  1350 * defs now admits additional type arguments, using TYPE('a) syntax;
  1351 
  1352 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1353 creates a new theory node; implicit merge of thms' signatures is
  1354 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1355 transfer:theory->thm->thm in (rare) cases;
  1356 
  1357 * improved handling of draft signatures / theories; draft thms (and
  1358 ctyps, cterms) are automatically promoted to real ones;
  1359 
  1360 * slightly changed interfaces for oracles: admit many per theory, named
  1361 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1362 
  1363 * print_goals: optional output of const types (set show_consts and
  1364 show_types);
  1365 
  1366 * improved output of warnings (###) and errors (***);
  1367 
  1368 * subgoal_tac displays a warning if the new subgoal has type variables;
  1369 
  1370 * removed old README and Makefiles;
  1371 
  1372 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1373 
  1374 * removed obsolete init_pps and init_database;
  1375 
  1376 * deleted the obsolete tactical STATE, which was declared by
  1377     fun STATE tacfun st = tacfun st st;
  1378 
  1379 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1380 (which abbreviates $HOME);
  1381 
  1382 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1383 use isatool fixseq to adapt your ML programs (this works for fully
  1384 qualified references to the Sequence structure only!);
  1385 
  1386 * use_thy no longer requires writable current directory; it always
  1387 reloads .ML *and* .thy file, if either one is out of date;
  1388 
  1389 
  1390 *** Classical Reasoner ***
  1391 
  1392 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1393 tactics that use classical reasoning to simplify a subgoal without
  1394 splitting it into several subgoals;
  1395 
  1396 * Safe_tac: like safe_tac but uses the default claset;
  1397 
  1398 
  1399 *** Simplifier ***
  1400 
  1401 * added simplification meta rules:
  1402     (asm_)(full_)simplify: simpset -> thm -> thm;
  1403 
  1404 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1405 logics (again);
  1406 
  1407 * added prems argument to simplification procedures;
  1408 
  1409 * HOL, FOL, ZF: added infix function `addsplits':
  1410   instead of `<simpset> setloop (split_tac <thms>)'
  1411   you can simply write `<simpset> addsplits <thms>'
  1412 
  1413 
  1414 *** Syntax ***
  1415 
  1416 * TYPE('a) syntax for type reflection terms;
  1417 
  1418 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1419 
  1420 * pretty printer: changed order of mixfix annotation preference (again!);
  1421 
  1422 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1423 
  1424 
  1425 *** HOL ***
  1426 
  1427 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1428   with `addloop' of the simplifier to faciliate case splitting in premises.
  1429 
  1430 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1431 
  1432 * HOL/Auth: new protocol proofs including some for the Internet
  1433   protocol TLS;
  1434 
  1435 * HOL/Map: new theory of `maps' a la VDM;
  1436 
  1437 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1438 cancelling out common nat summands from =, <, <= (in)equalities, or
  1439 differences; simplification procedures nat_cancel_factor for
  1440 cancelling common factor from =, <, <= (in)equalities over natural
  1441 sums; nat_cancel contains both kinds of procedures, it is installed by
  1442 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1443 
  1444 * HOL/simplifier: terms of the form
  1445   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1446   are rewritten to
  1447   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1448   and those of the form
  1449   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1450   are rewritten to
  1451   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1452 
  1453 * HOL/datatype
  1454   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1455 
  1456   P(t_case f1 ... fn x) =
  1457      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1458         ...
  1459        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1460      )
  1461 
  1462   and a theorem `split_t_case_asm' of the form
  1463 
  1464   P(t_case f1 ... fn x) =
  1465     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1466         ...
  1467        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1468      )
  1469   which can be added to a simpset via `addsplits'. The existing theorems
  1470   expand_list_case and expand_option_case have been renamed to
  1471   split_list_case and split_option_case.
  1472 
  1473 * HOL/Arithmetic:
  1474   - `pred n' is automatically converted to `n-1'.
  1475     Users are strongly encouraged not to use `pred' any longer,
  1476     because it will disappear altogether at some point.
  1477   - Users are strongly encouraged to write "0 < n" rather than
  1478     "n ~= 0". Theorems and proof tools have been modified towards this
  1479     `standard'.
  1480 
  1481 * HOL/Lists:
  1482   the function "set_of_list" has been renamed "set" (and its theorems too);
  1483   the function "nth" now takes its arguments in the reverse order and
  1484   has acquired the infix notation "!" as in "xs!n".
  1485 
  1486 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1487 
  1488 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1489   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1490 
  1491 * HOL/record: extensible records with schematic structural subtyping
  1492 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1493 still lacks various theorems and concrete record syntax;
  1494 
  1495 
  1496 *** HOLCF ***
  1497 
  1498 * removed "axioms" and "generated by" sections;
  1499 
  1500 * replaced "ops" section by extended "consts" section, which is capable of
  1501   handling the continuous function space "->" directly;
  1502 
  1503 * domain package:
  1504   . proves theorems immediately and stores them in the theory,
  1505   . creates hierachical name space,
  1506   . now uses normal mixfix annotations (instead of cinfix...),
  1507   . minor changes to some names and values (for consistency),
  1508   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1509   . separator between mutual domain defs: changed "," to "and",
  1510   . improved handling of sort constraints;  now they have to
  1511     appear on the left-hand side of the equations only;
  1512 
  1513 * fixed LAM <x,y,zs>.b syntax;
  1514 
  1515 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1516 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1517 
  1518 
  1519 *** FOL and ZF ***
  1520 
  1521 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1522   with `addloop' of the simplifier to faciliate case splitting in premises.
  1523 
  1524 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1525 in HOL, they strip ALL and --> from proved theorems;
  1526 
  1527 
  1528 
  1529 New in Isabelle94-8 (May 1997)
  1530 ------------------------------
  1531 
  1532 *** General Changes ***
  1533 
  1534 * new utilities to build / run / maintain Isabelle etc. (in parts
  1535 still somewhat experimental); old Makefiles etc. still functional;
  1536 
  1537 * new 'Isabelle System Manual';
  1538 
  1539 * INSTALL text, together with ./configure and ./build scripts;
  1540 
  1541 * reimplemented type inference for greater efficiency, better error
  1542 messages and clean internal interface;
  1543 
  1544 * prlim command for dealing with lots of subgoals (an easier way of
  1545 setting goals_limit);
  1546 
  1547 
  1548 *** Syntax ***
  1549 
  1550 * supports alternative (named) syntax tables (parser and pretty
  1551 printer); internal interface is provided by add_modesyntax(_i);
  1552 
  1553 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1554 be used in conjunction with the Isabelle symbol font; uses the
  1555 "symbols" syntax table;
  1556 
  1557 * added token_translation interface (may translate name tokens in
  1558 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1559 the current print_mode); IMPORTANT: user print translation functions
  1560 are responsible for marking newly introduced bounds
  1561 (Syntax.mark_boundT);
  1562 
  1563 * token translations for modes "xterm" and "xterm_color" that display
  1564 names in bold, underline etc. or colors (which requires a color
  1565 version of xterm);
  1566 
  1567 * infixes may now be declared with names independent of their syntax;
  1568 
  1569 * added typed_print_translation (like print_translation, but may
  1570 access type of constant);
  1571 
  1572 
  1573 *** Classical Reasoner ***
  1574 
  1575 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  1576 some limitations.  Blast_tac...
  1577   + ignores addss, addbefore, addafter; this restriction is intrinsic
  1578   + ignores elimination rules that don't have the correct format
  1579         (the conclusion MUST be a formula variable)
  1580   + ignores types, which can make HOL proofs fail
  1581   + rules must not require higher-order unification, e.g. apply_type in ZF
  1582     [message "Function Var's argument not a bound variable" relates to this]
  1583   + its proof strategy is more general but can actually be slower
  1584 
  1585 * substitution with equality assumptions no longer permutes other
  1586 assumptions;
  1587 
  1588 * minor changes in semantics of addafter (now called addaltern); renamed
  1589 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  1590 (and access functions for it);
  1591 
  1592 * improved combination of classical reasoner and simplifier:
  1593   + functions for handling clasimpsets
  1594   + improvement of addss: now the simplifier is called _after_ the
  1595     safe steps.
  1596   + safe variant of addss called addSss: uses safe simplifications
  1597     _during_ the safe steps. It is more complete as it allows multiple
  1598     instantiations of unknowns (e.g. with slow_tac).
  1599 
  1600 *** Simplifier ***
  1601 
  1602 * added interface for simplification procedures (functions that
  1603 produce *proven* rewrite rules on the fly, depending on current
  1604 redex);
  1605 
  1606 * ordering on terms as parameter (used for ordered rewriting);
  1607 
  1608 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  1609 
  1610 * the solver is now split into a safe and an unsafe part.
  1611 This should be invisible for the normal user, except that the
  1612 functions setsolver and addsolver have been renamed to setSolver and
  1613 addSolver; added safe_asm_full_simp_tac;
  1614 
  1615 
  1616 *** HOL ***
  1617 
  1618 * a generic induction tactic `induct_tac' which works for all datatypes and
  1619 also for type `nat';
  1620 
  1621 * a generic case distinction tactic `exhaust_tac' which works for all
  1622 datatypes and also for type `nat';
  1623 
  1624 * each datatype comes with a function `size';
  1625 
  1626 * patterns in case expressions allow tuple patterns as arguments to
  1627 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1628 
  1629 * primrec now also works with type nat;
  1630 
  1631 * recdef: a new declaration form, allows general recursive functions to be
  1632 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1633 
  1634 * the constant for negation has been renamed from "not" to "Not" to
  1635 harmonize with FOL, ZF, LK, etc.;
  1636 
  1637 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1638 infinite lists;
  1639 
  1640 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1641 
  1642 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1643 problems in commutative rings, using axiomatic type classes for + and *;
  1644 
  1645 * more examples in HOL/MiniML and HOL/Auth;
  1646 
  1647 * more default rewrite rules for quantifiers, union/intersection;
  1648 
  1649 * a new constant `arbitrary == @x.False';
  1650 
  1651 * HOLCF/IOA replaces old HOL/IOA;
  1652 
  1653 * HOLCF changes: derived all rules and arities
  1654   + axiomatic type classes instead of classes
  1655   + typedef instead of faking type definitions
  1656   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1657   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1658   + eliminated the types void, one, tr
  1659   + use unit lift and bool lift (with translations) instead of one and tr
  1660   + eliminated blift from Lift3.thy (use Def instead of blift)
  1661   all eliminated rules are derived as theorems --> no visible changes ;
  1662 
  1663 
  1664 *** ZF ***
  1665 
  1666 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1667 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1668 as ZF_cs addSIs [equalityI];
  1669 
  1670 
  1671 
  1672 New in Isabelle94-7 (November 96)
  1673 ---------------------------------
  1674 
  1675 * allowing negative levels (as offsets) in prlev and choplev;
  1676 
  1677 * super-linear speedup for large simplifications;
  1678 
  1679 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1680 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1681 FAIL); can suppress it using the command Delsimps (ex_simps @
  1682 all_simps); De Morgan laws are also now included, by default;
  1683 
  1684 * improved printing of ==>  :  ~:
  1685 
  1686 * new object-logic "Sequents" adds linear logic, while replacing LK
  1687 and Modal (thanks to Sara Kalvala);
  1688 
  1689 * HOL/Auth: correctness proofs for authentication protocols;
  1690 
  1691 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1692 examples on HOL/Auth);
  1693 
  1694 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1695 the rewriter and classical reasoner simultaneously;
  1696 
  1697 * function uresult no longer returns theorems in "standard" format;
  1698 regain previous version by: val uresult = standard o uresult;
  1699 
  1700 
  1701 
  1702 New in Isabelle94-6
  1703 -------------------
  1704 
  1705 * oracles -- these establish an interface between Isabelle and trusted
  1706 external reasoners, which may deliver results as theorems;
  1707 
  1708 * proof objects (in particular record all uses of oracles);
  1709 
  1710 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1711 
  1712 * "constdefs" section in theory files;
  1713 
  1714 * "primrec" section (HOL) no longer requires names;
  1715 
  1716 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1717 
  1718 
  1719 
  1720 New in Isabelle94-5
  1721 -------------------
  1722 
  1723 * reduced space requirements;
  1724 
  1725 * automatic HTML generation from theories;
  1726 
  1727 * theory files no longer require "..." (quotes) around most types;
  1728 
  1729 * new examples, including two proofs of the Church-Rosser theorem;
  1730 
  1731 * non-curried (1994) version of HOL is no longer distributed;
  1732 
  1733 
  1734 
  1735 New in Isabelle94-4
  1736 -------------------
  1737 
  1738 * greatly reduced space requirements;
  1739 
  1740 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1741 
  1742 * searchable theorem database (see the section "Retrieving theorems" on
  1743 page 8 of the Reference Manual);
  1744 
  1745 * new examples, including Grabczewski's monumental case study of the
  1746 Axiom of Choice;
  1747 
  1748 * The previous version of HOL renamed to Old_HOL;
  1749 
  1750 * The new version of HOL (previously called CHOL) uses a curried syntax
  1751 for functions.  Application looks like f a b instead of f(a,b);
  1752 
  1753 * Mutually recursive inductive definitions finally work in HOL;
  1754 
  1755 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1756 translates to the operator "split";
  1757 
  1758 
  1759 
  1760 New in Isabelle94-3
  1761 -------------------
  1762 
  1763 * new infix operator, addss, allowing the classical reasoner to
  1764 perform simplification at each step of its search.  Example:
  1765         fast_tac (cs addss ss)
  1766 
  1767 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1768 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1769 look like (a,b) instead of <a,b>;
  1770 
  1771 * PLEASE NOTE: CHOL will eventually replace HOL!
  1772 
  1773 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1774 It translates to the operator "split".  A new theory of integers is available;
  1775 
  1776 * In ZF, integer numerals now denote two's-complement binary integers.
  1777 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1778 
  1779 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1780 of the Axiom of Choice;
  1781 
  1782 
  1783 
  1784 New in Isabelle94-2
  1785 -------------------
  1786 
  1787 * Significantly faster resolution;
  1788 
  1789 * the different sections in a .thy file can now be mixed and repeated
  1790 freely;
  1791 
  1792 * Database of theorems for FOL, HOL and ZF.  New
  1793 commands including qed, qed_goal and bind_thm store theorems in the database.
  1794 
  1795 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1796 a given theory (thms_of), or find out what theory a theorem was proved in
  1797 (theory_of_thm);
  1798 
  1799 * Bugs fixed in the inductive definition and datatype packages;
  1800 
  1801 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1802 and HOL_dup_cs obsolete;
  1803 
  1804 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1805 have been removed;
  1806 
  1807 * Simpler definition of function space in ZF;
  1808 
  1809 * new results about cardinal and ordinal arithmetic in ZF;
  1810 
  1811 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1812 types;
  1813 
  1814 
  1815 $Id$