NEWS
author paulson
Wed Jul 25 13:13:01 2001 +0200 (2001-07-25)
changeset 11451 8abfb4f7bd02
parent 11437 2338bce575ae
child 11474 d15bb7695339
permissions -rw-r--r--
partial restructuring to reduce dependence on Axiom of Choice
     1 
     2 Isabelle NEWS -- history user-relevant changes
     3 ==============================================
     4 
     5 * HOL: added "The" definite description operator;
     6 
     7 * print modes "type_brackets" and "no_type_brackets" control output of
     8 nested => (types); the default behaviour is "brackets";
     9 
    10 * Classical reasoner: renamed addaltern to addafter, addSaltern to
    11 addSafter;
    12 
    13 * HOL: introduced f^n = f o ... o f
    14   WARNING: due to the limits of Isabelle's type classes, ^ on functions and
    15   relations has too general a domain, namely ('a * 'b)set and 'a => 'b.
    16   This means that it may be necessary to attach explicit type constraints.
    17 
    18 * HOL: added safe wrapper "split_conv_tac" to claset.  EXISTING PROOFS
    19 MAY FAIL;
    20 
    21 * HOL: made split_all_tac safe. EXISTING PROOFS MAY FAIL OR LOOP, so in this
    22   (rare) case use   delSWrapper "split_all_tac" addSbefore 
    23                     ("unsafe_split_all_tac", unsafe_split_all_tac)
    24 
    25 * HOL/GroupTheory: group theory examples including Sylow's theorem, by Florian
    26   Kammueller;
    27 
    28 * ZF: the integer library now covers quotients and remainders, with many laws
    29 relating division to addition, multiplication, etc.;
    30 
    31 
    32 New in Isabelle99-2 (February 2001)
    33 -----------------------------------
    34 
    35 *** Overview of INCOMPATIBILITIES ***
    36 
    37 * HOL: please note that theories in the Library and elsewhere often use the
    38 new-style (Isar) format; to refer to their theorems in an ML script you must
    39 bind them to ML identifers by e.g.	val thm_name = thm "thm_name";
    40 
    41 * HOL: inductive package no longer splits induction rule aggressively,
    42 but only as far as specified by the introductions given; the old
    43 format may be recovered via ML function complete_split_rule or attribute
    44 'split_rule (complete)';
    45 
    46 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
    47 gfp_Tarski to gfp_unfold;
    48 
    49 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
    50 
    51 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
    52 relation); infix "^^" has been renamed "``"; infix "``" has been
    53 renamed "`"; "univalent" has been renamed "single_valued";
    54 
    55 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
    56 operation;
    57 
    58 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
    59 
    60 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
    61 
    62 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
    63 consequence, it is no longer monotonic wrt. the local goal context
    64 (which is now passed through the inductive cases);
    65 
    66 * Document preparation: renamed standard symbols \<ll> to \<lless> and
    67 \<gg> to \<ggreater>;
    68 
    69 
    70 *** Document preparation ***
    71 
    72 * \isabellestyle{NAME} selects version of Isabelle output (currently
    73 available: are "it" for near math-mode best-style output, "sl" for
    74 slanted text style, and "tt" for plain type-writer; if no
    75 \isabellestyle command is given, output is according to slanted
    76 type-writer);
    77 
    78 * support sub/super scripts (for single symbols only), input syntax is
    79 like this: "A\<^sup>*" or "A\<^sup>\<star>";
    80 
    81 * some more standard symbols; see Appendix A of the system manual for
    82 the complete list of symbols defined in isabellesym.sty;
    83 
    84 * improved isabelle style files; more abstract symbol implementation
    85 (should now use \isamath{...} and \isatext{...} in custom symbol
    86 definitions);
    87 
    88 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
    89 state; Note that presentation of goal states does not conform to
    90 actual human-readable proof documents.  Please do not include goal
    91 states into document output unless you really know what you are doing!
    92 
    93 * proper indentation of antiquoted output with proportional LaTeX
    94 fonts;
    95 
    96 * no_document ML operator temporarily disables LaTeX document
    97 generation;
    98 
    99 * isatool unsymbolize tunes sources for plain ASCII communication;
   100 
   101 
   102 *** Isar ***
   103 
   104 * Pure: Isar now suffers initial goal statements to contain unbound
   105 schematic variables (this does not conform to actual readable proof
   106 documents, due to unpredictable outcome and non-compositional proof
   107 checking); users who know what they are doing may use schematic goals
   108 for Prolog-style synthesis of proven results;
   109 
   110 * Pure: assumption method (an implicit finishing) now handles actual
   111 rules as well;
   112 
   113 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   114 initial goal, declare "that" only as Pure intro (only for single
   115 steps); the "that" rule assumption may now be involved in implicit
   116 finishing, thus ".." becomes a feasible for trivial obtains;
   117 
   118 * Pure: default proof step now includes 'intro_classes'; thus trivial
   119 instance proofs may be performed by "..";
   120 
   121 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   122 statements as well;
   123 
   124 * Pure: more robust selection of calculational rules;
   125 
   126 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   127 rule (as well as the assumption rule);
   128 
   129 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   130 lemmas, using the graph browser tool;
   131 
   132 * Pure: predict failure of "show" in interactive mode;
   133 
   134 * Pure: 'thms_containing' now takes actual terms as arguments;
   135 
   136 * HOL: improved method 'induct' --- now handles non-atomic goals
   137 (potential INCOMPATIBILITY); tuned error handling;
   138 
   139 * HOL: cases and induct rules now provide explicit hints about the
   140 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   141 any remaining facts are inserted into the goal verbatim;
   142 
   143 * HOL: local contexts (aka cases) may now contain term bindings as
   144 well; the 'cases' and 'induct' methods new provide a ?case binding for
   145 the result to be shown in each case;
   146 
   147 * HOL: added 'recdef_tc' command;
   148 
   149 * isatool convert assists in eliminating legacy ML scripts;
   150 
   151 
   152 *** HOL ***
   153 
   154 * HOL/Library: a collection of generic theories to be used together
   155 with main HOL; the theory loader path already includes this directory
   156 by default; the following existing theories have been moved here:
   157 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   158 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   159 
   160 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   161 modelling and verification task performed in Isabelle/HOL +
   162 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   163 
   164 * HOL/Algebra: special summation operator SUM no longer exists, it has
   165 been replaced by setsum; infix 'assoc' now has priority 50 (like
   166 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   167 'domain', this makes the theory consistent with mathematical
   168 literature;
   169 
   170 * HOL basics: added overloaded operations "inverse" and "divide"
   171 (infix "/"), syntax for generic "abs" operation, generic summation
   172 operator \<Sum>;
   173 
   174 * HOL/typedef: simplified package, provide more useful rules (see also
   175 HOL/subset.thy);
   176 
   177 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   178 now expressed as a proper nested rule (old-style tactic scripts may
   179 require atomize_strip_tac to cope with non-atomic premises);
   180 
   181 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   182 to "split_conv" (old name still available for compatibility);
   183 
   184 * HOL: improved concrete syntax for strings (e.g. allows translation
   185 rules with string literals);
   186 
   187 * HOL-Hyperreal: a new target, extending HOL-Real with the hyperreals
   188 and Fleuriot's mechanization of analysis;
   189 
   190 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   191 
   192 
   193 *** CTT ***
   194 
   195 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   196 "lam" is displayed as TWO lambda-symbols
   197 
   198 * CTT: theory Main now available, containing everything (that is, Bool
   199 and Arith);
   200 
   201 
   202 *** General ***
   203 
   204 * Pure: the Simplifier has been implemented properly as a derived rule
   205 outside of the actual kernel (at last!); the overall performance
   206 penalty in practical applications is about 50%, while reliability of
   207 the Isabelle inference kernel has been greatly improved;
   208 
   209 * print modes "brackets" and "no_brackets" control output of nested =>
   210 (types) and ==> (props); the default behaviour is "brackets";
   211 
   212 * Provers: fast_tac (and friends) now handle actual object-logic rules
   213 as assumptions as well;
   214 
   215 * system: support Poly/ML 4.0;
   216 
   217 * system: isatool install handles KDE version 1 or 2;
   218 
   219 
   220 
   221 New in Isabelle99-1 (October 2000)
   222 ----------------------------------
   223 
   224 *** Overview of INCOMPATIBILITIES ***
   225 
   226 * HOL: simplification of natural numbers is much changed; to partly
   227 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   228 issue the following ML commands:
   229 
   230   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   231   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   232 
   233 * HOL: simplification no longer dives into case-expressions; this is
   234 controlled by "t.weak_case_cong" for each datatype t;
   235 
   236 * HOL: nat_less_induct renamed to less_induct;
   237 
   238 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   239 fixsome to patch .thy and .ML sources automatically;
   240 
   241   select_equality  -> some_equality
   242   select_eq_Ex     -> some_eq_ex
   243   selectI2EX       -> someI2_ex
   244   selectI2         -> someI2
   245   selectI          -> someI
   246   select1_equality -> some1_equality
   247   Eps_sym_eq       -> some_sym_eq_trivial
   248   Eps_eq           -> some_eq_trivial
   249 
   250 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   251 
   252 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   253 instead);
   254 
   255 * HOL: the recursion equations generated by 'recdef' are now called
   256 f.simps instead of f.rules;
   257 
   258 * HOL: qed_spec_mp now also handles bounded ALL as well;
   259 
   260 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   261 sometimes be needed;
   262 
   263 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   264 
   265 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   266 
   267 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   268 product is now "<*>" instead of "Times"; the lexicographic product is
   269 now "<*lex*>" instead of "**";
   270 
   271 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   272 of main HOL, but was unused); better use HOL's datatype package;
   273 
   274 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   275 the old syntax may be recovered as follows:
   276 
   277   syntax (symbols)
   278     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   279       (infixl "\\<oplus>" 100)
   280 
   281 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   282 
   283 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   284 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   285 internally;
   286 
   287 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   288 changed from A/r to A//r;
   289 
   290 * ZF: new treatment of arithmetic (nat & int) may break some old
   291 proofs;
   292 
   293 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   294 rulify -> rule_format, elimify -> elim_format, ...);
   295 
   296 * Isar/Provers: intro/elim/dest attributes changed; renamed
   297 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   298 should have to change intro!! to intro? only); replaced "delrule" by
   299 "rule del";
   300 
   301 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   302 
   303 * Provers: strengthened force_tac by using new first_best_tac;
   304 
   305 * LaTeX document preparation: several changes of isabelle.sty (see
   306 lib/texinputs);
   307 
   308 
   309 *** Document preparation ***
   310 
   311 * formal comments (text blocks etc.) in new-style theories may now
   312 contain antiquotations of thm/prop/term/typ/text to be presented
   313 according to latex print mode; concrete syntax is like this:
   314 @{term[show_types] "f(x) = a + x"};
   315 
   316 * isatool mkdir provides easy setup of Isabelle session directories,
   317 including proper document sources;
   318 
   319 * generated LaTeX sources are now deleted after successful run
   320 (isatool document -c); may retain a copy somewhere else via -D option
   321 of isatool usedir;
   322 
   323 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   324 style files, achieving self-contained LaTeX sources and simplifying
   325 LaTeX debugging;
   326 
   327 * old-style theories now produce (crude) LaTeX output as well;
   328 
   329 * browser info session directories are now self-contained (may be put
   330 on WWW server seperately); improved graphs of nested sessions; removed
   331 graph for 'all sessions';
   332 
   333 * several improvements in isabelle style files; \isabellestyle{it}
   334 produces fake math mode output; \isamarkupheader is now \section by
   335 default; see lib/texinputs/isabelle.sty etc.;
   336 
   337 
   338 *** Isar ***
   339 
   340 * Isar/Pure: local results and corresponding term bindings are now
   341 subject to Hindley-Milner polymorphism (similar to ML); this
   342 accommodates incremental type-inference very nicely;
   343 
   344 * Isar/Pure: new derived language element 'obtain' supports
   345 generalized existence reasoning;
   346 
   347 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   348 support accumulation of results, without applying any rules yet;
   349 useful to collect intermediate results without explicit name
   350 references, and for use with transitivity rules with more than 2
   351 premises;
   352 
   353 * Isar/Pure: scalable support for case-analysis type proofs: new
   354 'case' language element refers to local contexts symbolically, as
   355 produced by certain proof methods; internally, case names are attached
   356 to theorems as "tags";
   357 
   358 * Isar/Pure: theory command 'hide' removes declarations from
   359 class/type/const name spaces;
   360 
   361 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   362 indicate potential overloading;
   363 
   364 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   365 
   366 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   367 "{a,b,c}" instead of {a,b,c};
   368 
   369 * Isar/Pure now provides its own version of intro/elim/dest
   370 attributes; useful for building new logics, but beware of confusion
   371 with the version in Provers/classical;
   372 
   373 * Isar/Pure: the local context of (non-atomic) goals is provided via
   374 case name 'antecedent';
   375 
   376 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   377 to the current context is now done automatically);
   378 
   379 * Isar/Pure: theory command 'method_setup' provides a simple interface
   380 for definining proof methods in ML;
   381 
   382 * Isar/Provers: intro/elim/dest attributes changed; renamed
   383 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   384 most cases, one should have to change intro!! to intro? only);
   385 replaced "delrule" by "rule del";
   386 
   387 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   388 'symmetric' attribute (the latter supercedes [RS sym]);
   389 
   390 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   391 method modifier); 'simp' method: 'only:' modifier removes loopers as
   392 well (including splits);
   393 
   394 * Isar/Provers: Simplifier and Classical methods now support all kind
   395 of modifiers used in the past, including 'cong', 'iff', etc.
   396 
   397 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   398 of Simplifier and Classical reasoner);
   399 
   400 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   401 now support named cases; major packages (inductive, datatype, primrec,
   402 recdef) support case names and properly name parameters;
   403 
   404 * Isar/HOL: new transitivity rules for substitution in inequalities --
   405 monotonicity conditions are extracted to be proven at end of
   406 calculations;
   407 
   408 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   409 method anyway;
   410 
   411 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   412 split_if split_if_asm; datatype package provides theorems foo.splits =
   413 foo.split foo.split_asm for each datatype;
   414 
   415 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   416 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   417 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   418 use "(cases (simplified))" method in proper proof texts);
   419 
   420 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   421 
   422 * Isar: names of theorems etc. may be natural numbers as well;
   423 
   424 * Isar: 'pr' command: optional arguments for goals_limit and
   425 ProofContext.prems_limit; no longer prints theory contexts, but only
   426 proof states;
   427 
   428 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   429 additional print modes to be specified; e.g. "pr(latex)" will print
   430 proof state according to the Isabelle LaTeX style;
   431 
   432 * Isar: improved support for emulating tactic scripts, including proof
   433 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   434 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   435 (for HOL datatypes);
   436 
   437 * Isar: simplified (more robust) goal selection of proof methods: 1st
   438 goal, all goals, or explicit goal specifier (tactic emulation); thus
   439 'proof method scripts' have to be in depth-first order;
   440 
   441 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   442 
   443 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   444 should instead use individual commands for printing items
   445 (print_commands, print_methods etc.);
   446 
   447 * Isar: added 'nothing' --- the empty list of theorems;
   448 
   449 
   450 *** HOL ***
   451 
   452 * HOL/MicroJava: formalization of a fragment of Java, together with a
   453 corresponding virtual machine and a specification of its bytecode
   454 verifier and a lightweight bytecode verifier, including proofs of
   455 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   456 Cornelia Pusch (see also the homepage of project Bali at
   457 http://isabelle.in.tum.de/Bali/);
   458 
   459 * HOL/Algebra: new theory of rings and univariate polynomials, by
   460 Clemens Ballarin;
   461 
   462 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   463 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   464 Rasmussen;
   465 
   466 * HOL/Lattice: fundamental concepts of lattice theory and order
   467 structures, including duals, properties of bounds versus algebraic
   468 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   469 Theorem for complete lattices etc.; may also serve as a demonstration
   470 for abstract algebraic reasoning using axiomatic type classes, and
   471 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   472 
   473 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   474 von Oheimb;
   475 
   476 * HOL/IMPP: extension of IMP with local variables and mutually
   477 recursive procedures, by David von Oheimb;
   478 
   479 * HOL/Lambda: converted into new-style theory and document;
   480 
   481 * HOL/ex/Multiquote: example of multiple nested quotations and
   482 anti-quotations -- basically a generalized version of de-Bruijn
   483 representation; very useful in avoiding lifting of operations;
   484 
   485 * HOL/record: added general record equality rule to simpset; fixed
   486 select-update simplification procedure to handle extended records as
   487 well; admit "r" as field name;
   488 
   489 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   490 other numeric types and also as the identity of groups, rings, etc.;
   491 
   492 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   493 Types nat and int belong to this axclass;
   494 
   495 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   496    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   497    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   498   two terms #m*u and #n*u are replaced by #(m+n)*u
   499     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   500   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   501     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   502 
   503 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   504 powerful prover for predicate logic but knows nothing of clasets; see
   505 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   506 
   507 * HOL: new version of "case_tac" subsumes both boolean case split and
   508 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   509 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   510 
   511 * HOL: simplification no longer dives into case-expressions: only the
   512 selector expression is simplified, but not the remaining arms; to
   513 enable full simplification of case-expressions for datatype t, you may
   514 remove t.weak_case_cong from the simpset, either globally (Delcongs
   515 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   516 
   517 * HOL/recdef: the recursion equations generated by 'recdef' for
   518 function 'f' are now called f.simps instead of f.rules; if all
   519 termination conditions are proved automatically, these simplification
   520 rules are added to the simpset, as in primrec; rules may be named
   521 individually as well, resulting in a separate list of theorems for
   522 each equation;
   523 
   524 * HOL/While is a new theory that provides a while-combinator. It
   525 permits the definition of tail-recursive functions without the
   526 provision of a termination measure. The latter is necessary once the
   527 invariant proof rule for while is applied.
   528 
   529 * HOL: new (overloaded) notation for the set of elements below/above
   530 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   531 
   532 * HOL: theorems impI, allI, ballI bound as "strip";
   533 
   534 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   535 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   536 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   537 
   538 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   539 
   540 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   541 main HOL, but was unused);
   542 
   543 * HOL: fewer consts declared as global (e.g. have to refer to
   544 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   545 
   546 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   547 in case of overlap with user translations (e.g. judgements over
   548 tuples); (note that the underlying logical represenation is still
   549 bogus);
   550 
   551 
   552 *** ZF ***
   553 
   554 * ZF: simplification automatically cancels common terms in arithmetic
   555 expressions over nat and int;
   556 
   557 * ZF: new treatment of nat to minimize type-checking: all operators
   558 coerce their operands to a natural number using the function natify,
   559 making the algebraic laws unconditional;
   560 
   561 * ZF: as above, for int: operators coerce their operands to an integer
   562 using the function intify;
   563 
   564 * ZF: the integer library now contains many of the usual laws for the
   565 orderings, including $<=, and monotonicity laws for $+ and $*;
   566 
   567 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
   568 simplification;
   569 
   570 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
   571 to the simplifier and classical reasoner simultaneously;
   572 
   573 
   574 *** General ***
   575 
   576 * Provers: blast_tac now handles actual object-logic rules as
   577 assumptions; note that auto_tac uses blast_tac internally as well;
   578 
   579 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
   580 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
   581 
   582 * Provers: delrules now handles destruct rules as well (no longer need
   583 explicit make_elim);
   584 
   585 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
   586   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   587 use instead the strong form,
   588   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   589 in HOL, FOL and ZF the function cla_make_elim will create such rules
   590 from destruct-rules;
   591 
   592 * Provers: Simplifier.easy_setup provides a fast path to basic
   593 Simplifier setup for new object-logics;
   594 
   595 * Pure: AST translation rules no longer require constant head on LHS;
   596 
   597 * Pure: improved name spaces: ambiguous output is qualified; support
   598 for hiding of names;
   599 
   600 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
   601 XSYMBOL_HOME; no longer need to do manual configuration in most
   602 situations;
   603 
   604 * system: compression of ML heaps images may now be controlled via -c
   605 option of isabelle and isatool usedir (currently only observed by
   606 Poly/ML);
   607 
   608 * system: isatool installfonts may handle X-Symbol fonts as well (very
   609 useful for remote X11);
   610 
   611 * system: provide TAGS file for Isabelle sources;
   612 
   613 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
   614 order;
   615 
   616 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
   617 timing flag supersedes proof_timing and Toplevel.trace;
   618 
   619 * ML: new combinators |>> and |>>> for incremental transformations
   620 with secondary results (e.g. certain theory extensions):
   621 
   622 * ML: PureThy.add_defs gets additional argument to indicate potential
   623 overloading (usually false);
   624 
   625 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
   626 results;
   627 
   628 
   629 
   630 New in Isabelle99 (October 1999)
   631 --------------------------------
   632 
   633 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   634 
   635 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
   636 are no longer simplified.  (This allows the simplifier to unfold recursive
   637 functional programs.)  To restore the old behaviour, declare
   638 
   639     Delcongs [if_weak_cong];
   640 
   641 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
   642 complement;
   643 
   644 * HOL: the predicate "inj" is now defined by translation to "inj_on";
   645 
   646 * HOL/datatype: mutual_induct_tac no longer exists --
   647   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
   648 
   649 * HOL/typedef: fixed type inference for representing set; type
   650 arguments now have to occur explicitly on the rhs as type constraints;
   651 
   652 * ZF: The con_defs part of an inductive definition may no longer refer
   653 to constants declared in the same theory;
   654 
   655 * HOL, ZF: the function mk_cases, generated by the inductive
   656 definition package, has lost an argument.  To simplify its result, it
   657 uses the default simpset instead of a supplied list of theorems.
   658 
   659 * HOL/List: the constructors of type list are now Nil and Cons;
   660 
   661 * Simplifier: the type of the infix ML functions
   662         setSSolver addSSolver setSolver addSolver
   663 is now  simpset * solver -> simpset  where `solver' is a new abstract type
   664 for packaging solvers. A solver is created via
   665         mk_solver: string -> (thm list -> int -> tactic) -> solver
   666 where the string argument is only a comment.
   667 
   668 
   669 *** Proof tools ***
   670 
   671 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
   672 decision procedure for linear arithmetic. Currently it is used for
   673 types `nat', `int', and `real' in HOL (see below); it can, should and
   674 will be instantiated for other types and logics as well.
   675 
   676 * The simplifier now accepts rewrite rules with flexible heads, eg
   677      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
   678   They are applied like any rule with a non-pattern lhs, i.e. by first-order
   679   matching.
   680 
   681 
   682 *** General ***
   683 
   684 * New Isabelle/Isar subsystem provides an alternative to traditional
   685 tactical theorem proving; together with the ProofGeneral/isar user
   686 interface it offers an interactive environment for developing human
   687 readable proof documents (Isar == Intelligible semi-automated
   688 reasoning); for further information see isatool doc isar-ref,
   689 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
   690 
   691 * improved and simplified presentation of theories: better HTML markup
   692 (including colors), graph views in several sizes; isatool usedir now
   693 provides a proper interface for user theories (via -P option); actual
   694 document preparation based on (PDF)LaTeX is available as well (for
   695 new-style theories only); see isatool doc system for more information;
   696 
   697 * native support for Proof General, both for classic Isabelle and
   698 Isabelle/Isar;
   699 
   700 * ML function thm_deps visualizes dependencies of theorems and lemmas,
   701 using the graph browser tool;
   702 
   703 * Isabelle manuals now also available as PDF;
   704 
   705 * theory loader rewritten from scratch (may not be fully
   706 bug-compatible); old loadpath variable has been replaced by show_path,
   707 add_path, del_path, reset_path functions; new operations such as
   708 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
   709 isatool doc ref);
   710 
   711 * improved isatool install: option -k creates KDE application icon,
   712 option -p DIR installs standalone binaries;
   713 
   714 * added ML_PLATFORM setting (useful for cross-platform installations);
   715 more robust handling of platform specific ML images for SML/NJ;
   716 
   717 * the settings environment is now statically scoped, i.e. it is never
   718 created again in sub-processes invoked from isabelle, isatool, or
   719 Isabelle;
   720 
   721 * path element specification '~~' refers to '$ISABELLE_HOME';
   722 
   723 * in locales, the "assumes" and "defines" parts may be omitted if
   724 empty;
   725 
   726 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   727 long arrows);
   728 
   729 * new print_mode "HTML";
   730 
   731 * new flag show_tags controls display of tags of theorems (which are
   732 basically just comments that may be attached by some tools);
   733 
   734 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   735 mode and goal output format:
   736 
   737 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   738 244c244
   739 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   740 ---
   741 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   742 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   743 181c181
   744 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   745 ---
   746 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   747 
   748 * function bind_thms stores lists of theorems (cf. bind_thm);
   749 
   750 * new shorthand tactics ftac, eatac, datac, fatac;
   751 
   752 * qed (and friends) now accept "" as result name; in that case the
   753 theorem is not stored, but proper checks and presentation of the
   754 result still apply;
   755 
   756 * theorem database now also indexes constants "Trueprop", "all",
   757 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   758 
   759 
   760 *** HOL ***
   761 
   762 ** HOL arithmetic **
   763 
   764 * There are now decision procedures for linear arithmetic over nat and
   765 int:
   766 
   767 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   768 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   769 are treated as atomic; subformulae not involving type `nat' or `int'
   770 are ignored; quantified subformulae are ignored unless they are
   771 positive universal or negative existential. The tactic has to be
   772 invoked by hand and can be a little bit slow. In particular, the
   773 running time is exponential in the number of occurrences of `min' and
   774 `max', and `-' on `nat'.
   775 
   776 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   777 (negated) (in)equalities among the premises and the conclusion into
   778 account (i.e. no compound formulae) and does not know about `min' and
   779 `max', and `-' on `nat'. It is fast and is used automatically by the
   780 simplifier.
   781 
   782 NB: At the moment, these decision procedures do not cope with mixed
   783 nat/int formulae where the two parts interact, such as `m < n ==>
   784 int(m) < int(n)'.
   785 
   786 * HOL/Numeral provides a generic theory of numerals (encoded
   787 efficiently as bit strings); setup for types nat/int/real is in place;
   788 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   789 int, existing theories and proof scripts may require a few additional
   790 type constraints;
   791 
   792 * integer division and remainder can now be performed on constant
   793 arguments;
   794 
   795 * many properties of integer multiplication, division and remainder
   796 are now available;
   797 
   798 * An interface to the Stanford Validity Checker (SVC) is available through the
   799 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   800 are proved automatically.  SVC must be installed separately, and its results
   801 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   802 invocation of the underlying oracle).  For SVC see
   803   http://verify.stanford.edu/SVC
   804 
   805 * IsaMakefile: the HOL-Real target now builds an actual image;
   806 
   807 
   808 ** HOL misc **
   809 
   810 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   811 (in Isabelle/Isar) -- by Gertrud Bauer;
   812 
   813 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   814 analysis for assembly languages with subtypes;
   815 
   816 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   817 -- avoids syntactic ambiguities and treats state, transition, and
   818 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   819 changed syntax and (many) tactics;
   820 
   821 * HOL/inductive: Now also handles more general introduction rules such
   822   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
   823   theorems are now maintained within the theory (maintained via the
   824   "mono" attribute);
   825 
   826 * HOL/datatype: Now also handles arbitrarily branching datatypes
   827   (using function types) such as
   828 
   829   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
   830 
   831 * HOL/record: record_simproc (part of the default simpset) takes care
   832 of selectors applied to updated records; record_split_tac is no longer
   833 part of the default claset; update_defs may now be removed from the
   834 simpset in many cases; COMPATIBILITY: old behavior achieved by
   835 
   836   claset_ref () := claset() addSWrapper record_split_wrapper;
   837   Delsimprocs [record_simproc]
   838 
   839 * HOL/typedef: fixed type inference for representing set; type
   840 arguments now have to occur explicitly on the rhs as type constraints;
   841 
   842 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
   843 names rather than an ML expression;
   844 
   845 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
   846 supplied later.  Program schemes can be defined, such as
   847     "While B C s = (if B s then While B C (C s) else s)"
   848 where the well-founded relation can be chosen after B and C have been given.
   849 
   850 * HOL/List: the constructors of type list are now Nil and Cons;
   851 INCOMPATIBILITY: while [] and infix # syntax is still there, of
   852 course, ML tools referring to List.list.op # etc. have to be adapted;
   853 
   854 * HOL_quantifiers flag superseded by "HOL" print mode, which is
   855 disabled by default; run isabelle with option -m HOL to get back to
   856 the original Gordon/HOL-style output;
   857 
   858 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
   859 ALL x<=y. P, EX x<y. P, EX x<=y. P;
   860 
   861 * HOL basic syntax simplified (more orthogonal): all variants of
   862 All/Ex now support plain / symbolic / HOL notation; plain syntax for
   863 Eps operator is provided as well: "SOME x. P[x]";
   864 
   865 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
   866 
   867 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
   868 thus available for user theories;
   869 
   870 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
   871 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
   872 time;
   873 
   874 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
   875 several times and then mp;
   876 
   877 
   878 *** LK ***
   879 
   880 * the notation <<...>> is now available as a notation for sequences of
   881 formulas;
   882 
   883 * the simplifier is now installed
   884 
   885 * the axiom system has been generalized (thanks to Soren Heilmann)
   886 
   887 * the classical reasoner now has a default rule database
   888 
   889 
   890 *** ZF ***
   891 
   892 * new primrec section allows primitive recursive functions to be given
   893 directly (as in HOL) over datatypes and the natural numbers;
   894 
   895 * new tactics induct_tac and exhaust_tac for induction (or case
   896 analysis) over datatypes and the natural numbers;
   897 
   898 * the datatype declaration of type T now defines the recursor T_rec;
   899 
   900 * simplification automatically does freeness reasoning for datatype
   901 constructors;
   902 
   903 * automatic type-inference, with AddTCs command to insert new
   904 type-checking rules;
   905 
   906 * datatype introduction rules are now added as Safe Introduction rules
   907 to the claset;
   908 
   909 * the syntax "if P then x else y" is now available in addition to
   910 if(P,x,y);
   911 
   912 
   913 *** Internal programming interfaces ***
   914 
   915 * tuned simplifier trace output; new flag debug_simp;
   916 
   917 * structures Vartab / Termtab (instances of TableFun) offer efficient
   918 tables indexed by indexname_ord / term_ord (compatible with aconv);
   919 
   920 * AxClass.axclass_tac lost the theory argument;
   921 
   922 * tuned current_goals_markers semantics: begin / end goal avoids
   923 printing empty lines;
   924 
   925 * removed prs and prs_fn hook, which was broken because it did not
   926 include \n in its semantics, forcing writeln to add one
   927 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
   928 string -> unit if you really want to output text without newline;
   929 
   930 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
   931 plain output, interface builders may have to enable 'isabelle_font'
   932 mode to get Isabelle font glyphs as before;
   933 
   934 * refined token_translation interface; INCOMPATIBILITY: output length
   935 now of type real instead of int;
   936 
   937 * theory loader actions may be traced via new ThyInfo.add_hook
   938 interface (see src/Pure/Thy/thy_info.ML); example application: keep
   939 your own database of information attached to *whole* theories -- as
   940 opposed to intra-theory data slots offered via TheoryDataFun;
   941 
   942 * proper handling of dangling sort hypotheses (at last!);
   943 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
   944 extra sort hypotheses that can be witnessed from the type signature;
   945 the force_strip_shyps flag is gone, any remaining shyps are simply
   946 left in the theorem (with a warning issued by strip_shyps_warning);
   947 
   948 
   949 
   950 New in Isabelle98-1 (October 1998)
   951 ----------------------------------
   952 
   953 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   954 
   955 * several changes of automated proof tools;
   956 
   957 * HOL: major changes to the inductive and datatype packages, including
   958 some minor incompatibilities of theory syntax;
   959 
   960 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
   961 called `inj_on';
   962 
   963 * HOL: removed duplicate thms in Arith:
   964   less_imp_add_less  should be replaced by  trans_less_add1
   965   le_imp_add_le      should be replaced by  trans_le_add1
   966 
   967 * HOL: unary minus is now overloaded (new type constraints may be
   968 required);
   969 
   970 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
   971 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
   972 now taken as an integer constant.
   973 
   974 * Pure: ML function 'theory_of' renamed to 'theory';
   975 
   976 
   977 *** Proof tools ***
   978 
   979 * Simplifier:
   980   1. Asm_full_simp_tac is now more aggressive.
   981      1. It will sometimes reorient premises if that increases their power to
   982         simplify.
   983      2. It does no longer proceed strictly from left to right but may also
   984         rotate premises to achieve further simplification.
   985      For compatibility reasons there is now Asm_lr_simp_tac which is like the
   986      old Asm_full_simp_tac in that it does not rotate premises.
   987   2. The simplifier now knows a little bit about nat-arithmetic.
   988 
   989 * Classical reasoner: wrapper mechanism for the classical reasoner now
   990 allows for selected deletion of wrappers, by introduction of names for
   991 wrapper functionals.  This implies that addbefore, addSbefore,
   992 addaltern, and addSaltern now take a pair (name, tactic) as argument,
   993 and that adding two tactics with the same name overwrites the first
   994 one (emitting a warning).
   995   type wrapper = (int -> tactic) -> (int -> tactic)
   996   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
   997   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
   998   delWrapper, delSWrapper: claset *  string            -> claset
   999   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1000 
  1001 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1002 semantics; addbefore now affects only the unsafe part of step_tac
  1003 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1004 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1005 by Force_tac;
  1006 
  1007 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1008 compWrapper; added safe wrapper (and access functions for it);
  1009 
  1010 * HOL/split_all_tac is now much faster and fails if there is nothing
  1011 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1012 and the names of the automatically generated variables have changed.
  1013 split_all_tac has moved within claset() from unsafe wrappers to safe
  1014 wrappers, which means that !!-bound variables are split much more
  1015 aggressively, and safe_tac and clarify_tac now split such variables.
  1016 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1017 Note: the same holds for record_split_tac, which does the job of
  1018 split_all_tac for record fields.
  1019 
  1020 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1021 permanently to the default simpset using Addsplits just like
  1022 Addsimps. They can be removed via Delsplits just like
  1023 Delsimps. Lower-case versions are also available.
  1024 
  1025 * HOL/Simplifier: The rule split_if is now part of the default
  1026 simpset. This means that the simplifier will eliminate all occurrences
  1027 of if-then-else in the conclusion of a goal. To prevent this, you can
  1028 either remove split_if completely from the default simpset by
  1029 `Delsplits [split_if]' or remove it in a specific call of the
  1030 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1031 other case splitting rules to/from the default simpset: every datatype
  1032 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1033 t is the name of the datatype).
  1034 
  1035 * Classical reasoner / Simplifier combination: new force_tac (and
  1036 derivatives Force_tac, force) combines rewriting and classical
  1037 reasoning (and whatever other tools) similarly to auto_tac, but is
  1038 aimed to solve the given subgoal completely.
  1039 
  1040 
  1041 *** General ***
  1042 
  1043 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1044 and `goalw': the theory is no longer needed as an explicit argument -
  1045 the current theory context is used; assumptions are no longer returned
  1046 at the ML-level unless one of them starts with ==> or !!; it is
  1047 recommended to convert to these new commands using isatool fixgoal
  1048 (backup your sources first!);
  1049 
  1050 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1051 the current theory context, and 'theory' to lookup stored theories;
  1052 
  1053 * new theory section 'locale' for declaring constants, assumptions and
  1054 definitions that have local scope;
  1055 
  1056 * new theory section 'nonterminals' for purely syntactic types;
  1057 
  1058 * new theory section 'setup' for generic ML setup functions
  1059 (e.g. package initialization);
  1060 
  1061 * the distribution now includes Isabelle icons: see
  1062 lib/logo/isabelle-{small,tiny}.xpm;
  1063 
  1064 * isatool install - install binaries with absolute references to
  1065 ISABELLE_HOME/bin;
  1066 
  1067 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1068 
  1069 * print mode 'emacs' reserved for Isamode;
  1070 
  1071 * support multiple print (ast) translations per constant name;
  1072 
  1073 * theorems involving oracles are now printed with a suffixed [!];
  1074 
  1075 
  1076 *** HOL ***
  1077 
  1078 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1079 
  1080 * HOL/inductive package reorganized and improved: now supports mutual
  1081 definitions such as
  1082 
  1083   inductive EVEN ODD
  1084     intrs
  1085       null "0 : EVEN"
  1086       oddI "n : EVEN ==> Suc n : ODD"
  1087       evenI "n : ODD ==> Suc n : EVEN"
  1088 
  1089 new theorem list "elims" contains an elimination rule for each of the
  1090 recursive sets; inductive definitions now handle disjunctive premises
  1091 correctly (also ZF);
  1092 
  1093 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1094 "mutual_induct" no longer exists - the induction rule is always
  1095 contained in "induct";
  1096 
  1097 
  1098 * HOL/datatype package re-implemented and greatly improved: now
  1099 supports mutually recursive datatypes such as
  1100 
  1101   datatype
  1102     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1103             | SUM ('a aexp) ('a aexp)
  1104             | DIFF ('a aexp) ('a aexp)
  1105             | NUM 'a
  1106   and
  1107     'a bexp = LESS ('a aexp) ('a aexp)
  1108             | AND ('a bexp) ('a bexp)
  1109             | OR ('a bexp) ('a bexp)
  1110 
  1111 as well as indirectly recursive datatypes such as
  1112 
  1113   datatype
  1114     ('a, 'b) term = Var 'a
  1115                   | App 'b ((('a, 'b) term) list)
  1116 
  1117 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1118 induction on mutually / indirectly recursive datatypes.
  1119 
  1120 Primrec equations are now stored in theory and can be accessed via
  1121 <function_name>.simps.
  1122 
  1123 INCOMPATIBILITIES:
  1124 
  1125   - Theories using datatypes must now have theory Datatype as an
  1126     ancestor.
  1127   - The specific <typename>.induct_tac no longer exists - use the
  1128     generic induct_tac instead.
  1129   - natE has been renamed to nat.exhaust - use exhaust_tac
  1130     instead of res_inst_tac ... natE. Note that the variable
  1131     names in nat.exhaust differ from the names in natE, this
  1132     may cause some "fragile" proofs to fail.
  1133   - The theorems split_<typename>_case and split_<typename>_case_asm
  1134     have been renamed to <typename>.split and <typename>.split_asm.
  1135   - Since default sorts of type variables are now handled correctly,
  1136     some datatype definitions may have to be annotated with explicit
  1137     sort constraints.
  1138   - Primrec definitions no longer require function name and type
  1139     of recursive argument.
  1140 
  1141 Consider using isatool fixdatatype to adapt your theories and proof
  1142 scripts to the new package (backup your sources first!).
  1143 
  1144 
  1145 * HOL/record package: considerably improved implementation; now
  1146 includes concrete syntax for record types, terms, updates; theorems
  1147 for surjective pairing and splitting !!-bound record variables; proof
  1148 support is as follows:
  1149 
  1150   1) standard conversions (selectors or updates applied to record
  1151 constructor terms) are part of the standard simpset;
  1152 
  1153   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1154 made part of standard simpset and claset via addIffs;
  1155 
  1156   3) a tactic for record field splitting (record_split_tac) is part of
  1157 the standard claset (addSWrapper);
  1158 
  1159 To get a better idea about these rules you may retrieve them via
  1160 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1161 the name of your record type.
  1162 
  1163 The split tactic 3) conceptually simplifies by the following rule:
  1164 
  1165   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1166 
  1167 Thus any record variable that is bound by meta-all will automatically
  1168 blow up into some record constructor term, consequently the
  1169 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1170 solve record problems automatically.
  1171 
  1172 
  1173 * reorganized the main HOL image: HOL/Integ and String loaded by
  1174 default; theory Main includes everything;
  1175 
  1176 * automatic simplification of integer sums and comparisons, using cancellation;
  1177 
  1178 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1179 
  1180 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1181 
  1182 * many new identities for unions, intersections, set difference, etc.;
  1183 
  1184 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1185 called split_if, split_split, split_sum_case and split_nat_case (to go
  1186 with add/delsplits);
  1187 
  1188 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1189 (?x::unit) = (); this is made part of the default simpset, which COULD
  1190 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1191 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1192 unit_abs_eta_conv is added in order to counter the effect of
  1193 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1194 %u.f();
  1195 
  1196 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1197 makes more sense);
  1198 
  1199 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1200   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1201   disjointness reasoning but breaking a few old proofs.
  1202 
  1203 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1204 to 'converse' from 'inverse' (for compatibility with ZF and some
  1205 literature);
  1206 
  1207 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1208 the well-founded relation;
  1209 
  1210 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1211     Compl A.  The "Compl" syntax remains available as input syntax for this
  1212     release ONLY.
  1213 
  1214 * HOL/Update: new theory of function updates:
  1215     f(a:=b) == %x. if x=a then b else f x
  1216 may also be iterated as in f(a:=b,c:=d,...);
  1217 
  1218 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1219 
  1220 * HOL/List:
  1221   - new function list_update written xs[i:=v] that updates the i-th
  1222     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1223   - new function `upt' written [i..j(] which generates the list
  1224     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1225     bound write [i..j], which is a shorthand for [i..j+1(].
  1226   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1227 
  1228 * HOL/Arith:
  1229   - removed 'pred' (predecessor) function;
  1230   - generalized some theorems about n-1;
  1231   - many new laws about "div" and "mod";
  1232   - new laws about greatest common divisors (see theory ex/Primes);
  1233 
  1234 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1235 instead of "inverse";
  1236 
  1237 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1238   of the multiset ordering;
  1239 
  1240 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1241   (not included by default);
  1242 
  1243 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1244 
  1245 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1246   programs, i.e. different program variables may have different types.
  1247 
  1248 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1249   [previously, this check worked only if the rewrite rule was unconditional]
  1250   Now rew can involve either definitions or equalities (either == or =).
  1251 
  1252 
  1253 *** ZF ***
  1254 
  1255 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1256   only the theorems proved on ZF.ML;
  1257 
  1258 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1259   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1260   disjointness reasoning but breaking a few old proofs.
  1261 
  1262 * ZF/Update: new theory of function updates
  1263     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1264   may also be iterated as in f(a:=b,c:=d,...);
  1265 
  1266 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1267 
  1268 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1269   [previously, this check worked only if the rewrite rule was unconditional]
  1270   Now rew can involve either definitions or equalities (either == or =).
  1271 
  1272 * case_tac provided for compatibility with HOL
  1273     (like the old excluded_middle_tac, but with subgoals swapped)
  1274 
  1275 
  1276 *** Internal programming interfaces ***
  1277 
  1278 * Pure: several new basic modules made available for general use, see
  1279 also src/Pure/README;
  1280 
  1281 * improved the theory data mechanism to support encapsulation (data
  1282 kind name replaced by private Object.kind, acting as authorization
  1283 key); new type-safe user interface via functor TheoryDataFun; generic
  1284 print_data function becomes basically useless;
  1285 
  1286 * removed global_names compatibility flag -- all theory declarations
  1287 are qualified by default;
  1288 
  1289 * module Pure/Syntax now offers quote / antiquote translation
  1290 functions (useful for Hoare logic etc. with implicit dependencies);
  1291 see HOL/ex/Antiquote for an example use;
  1292 
  1293 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1294 cterm -> thm;
  1295 
  1296 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1297 subgoal;
  1298 
  1299 * Display.print_goals function moved to Locale.print_goals;
  1300 
  1301 * standard print function for goals supports current_goals_markers
  1302 variable for marking begin of proof, end of proof, start of goal; the
  1303 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1304 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1305 for example;
  1306 
  1307 
  1308 
  1309 New in Isabelle98 (January 1998)
  1310 --------------------------------
  1311 
  1312 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1313 
  1314 * changed lexical syntax of terms / types: dots made part of long
  1315 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1316 
  1317 * simpset (and claset) reference variable replaced by functions
  1318 simpset / simpset_ref;
  1319 
  1320 * no longer supports theory aliases (via merge) and non-trivial
  1321 implicit merge of thms' signatures;
  1322 
  1323 * most internal names of constants changed due to qualified names;
  1324 
  1325 * changed Pure/Sequence interface (see Pure/seq.ML);
  1326 
  1327 
  1328 *** General Changes ***
  1329 
  1330 * hierachically structured name spaces (for consts, types, axms, thms
  1331 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1332 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1333 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1334 long_names for fully qualified output names; NOTE: ML programs
  1335 (special tactics, packages etc.) referring to internal names may have
  1336 to be adapted to cope with fully qualified names; in case of severe
  1337 backward campatibility problems try setting 'global_names' at compile
  1338 time to have enrything declared within a flat name space; one may also
  1339 fine tune name declarations in theories via the 'global' and 'local'
  1340 section;
  1341 
  1342 * reimplemented the implicit simpset and claset using the new anytype
  1343 data filed in signatures; references simpset:simpset ref etc. are
  1344 replaced by functions simpset:unit->simpset and
  1345 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1346 to patch your ML files accordingly;
  1347 
  1348 * HTML output now includes theory graph data for display with Java
  1349 applet or isatool browser; data generated automatically via isatool
  1350 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1351 
  1352 * defs may now be conditional; improved rewrite_goals_tac to handle
  1353 conditional equations;
  1354 
  1355 * defs now admits additional type arguments, using TYPE('a) syntax;
  1356 
  1357 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1358 creates a new theory node; implicit merge of thms' signatures is
  1359 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1360 transfer:theory->thm->thm in (rare) cases;
  1361 
  1362 * improved handling of draft signatures / theories; draft thms (and
  1363 ctyps, cterms) are automatically promoted to real ones;
  1364 
  1365 * slightly changed interfaces for oracles: admit many per theory, named
  1366 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1367 
  1368 * print_goals: optional output of const types (set show_consts and
  1369 show_types);
  1370 
  1371 * improved output of warnings (###) and errors (***);
  1372 
  1373 * subgoal_tac displays a warning if the new subgoal has type variables;
  1374 
  1375 * removed old README and Makefiles;
  1376 
  1377 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1378 
  1379 * removed obsolete init_pps and init_database;
  1380 
  1381 * deleted the obsolete tactical STATE, which was declared by
  1382     fun STATE tacfun st = tacfun st st;
  1383 
  1384 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1385 (which abbreviates $HOME);
  1386 
  1387 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1388 use isatool fixseq to adapt your ML programs (this works for fully
  1389 qualified references to the Sequence structure only!);
  1390 
  1391 * use_thy no longer requires writable current directory; it always
  1392 reloads .ML *and* .thy file, if either one is out of date;
  1393 
  1394 
  1395 *** Classical Reasoner ***
  1396 
  1397 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1398 tactics that use classical reasoning to simplify a subgoal without
  1399 splitting it into several subgoals;
  1400 
  1401 * Safe_tac: like safe_tac but uses the default claset;
  1402 
  1403 
  1404 *** Simplifier ***
  1405 
  1406 * added simplification meta rules:
  1407     (asm_)(full_)simplify: simpset -> thm -> thm;
  1408 
  1409 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1410 logics (again);
  1411 
  1412 * added prems argument to simplification procedures;
  1413 
  1414 * HOL, FOL, ZF: added infix function `addsplits':
  1415   instead of `<simpset> setloop (split_tac <thms>)'
  1416   you can simply write `<simpset> addsplits <thms>'
  1417 
  1418 
  1419 *** Syntax ***
  1420 
  1421 * TYPE('a) syntax for type reflection terms;
  1422 
  1423 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1424 
  1425 * pretty printer: changed order of mixfix annotation preference (again!);
  1426 
  1427 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1428 
  1429 
  1430 *** HOL ***
  1431 
  1432 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1433   with `addloop' of the simplifier to faciliate case splitting in premises.
  1434 
  1435 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1436 
  1437 * HOL/Auth: new protocol proofs including some for the Internet
  1438   protocol TLS;
  1439 
  1440 * HOL/Map: new theory of `maps' a la VDM;
  1441 
  1442 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1443 cancelling out common nat summands from =, <, <= (in)equalities, or
  1444 differences; simplification procedures nat_cancel_factor for
  1445 cancelling common factor from =, <, <= (in)equalities over natural
  1446 sums; nat_cancel contains both kinds of procedures, it is installed by
  1447 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1448 
  1449 * HOL/simplifier: terms of the form
  1450   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1451   are rewritten to
  1452   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1453   and those of the form
  1454   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1455   are rewritten to
  1456   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1457 
  1458 * HOL/datatype
  1459   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1460 
  1461   P(t_case f1 ... fn x) =
  1462      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1463         ...
  1464        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1465      )
  1466 
  1467   and a theorem `split_t_case_asm' of the form
  1468 
  1469   P(t_case f1 ... fn x) =
  1470     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1471         ...
  1472        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1473      )
  1474   which can be added to a simpset via `addsplits'. The existing theorems
  1475   expand_list_case and expand_option_case have been renamed to
  1476   split_list_case and split_option_case.
  1477 
  1478 * HOL/Arithmetic:
  1479   - `pred n' is automatically converted to `n-1'.
  1480     Users are strongly encouraged not to use `pred' any longer,
  1481     because it will disappear altogether at some point.
  1482   - Users are strongly encouraged to write "0 < n" rather than
  1483     "n ~= 0". Theorems and proof tools have been modified towards this
  1484     `standard'.
  1485 
  1486 * HOL/Lists:
  1487   the function "set_of_list" has been renamed "set" (and its theorems too);
  1488   the function "nth" now takes its arguments in the reverse order and
  1489   has acquired the infix notation "!" as in "xs!n".
  1490 
  1491 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1492 
  1493 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1494   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1495 
  1496 * HOL/record: extensible records with schematic structural subtyping
  1497 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1498 still lacks various theorems and concrete record syntax;
  1499 
  1500 
  1501 *** HOLCF ***
  1502 
  1503 * removed "axioms" and "generated by" sections;
  1504 
  1505 * replaced "ops" section by extended "consts" section, which is capable of
  1506   handling the continuous function space "->" directly;
  1507 
  1508 * domain package:
  1509   . proves theorems immediately and stores them in the theory,
  1510   . creates hierachical name space,
  1511   . now uses normal mixfix annotations (instead of cinfix...),
  1512   . minor changes to some names and values (for consistency),
  1513   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1514   . separator between mutual domain defs: changed "," to "and",
  1515   . improved handling of sort constraints;  now they have to
  1516     appear on the left-hand side of the equations only;
  1517 
  1518 * fixed LAM <x,y,zs>.b syntax;
  1519 
  1520 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1521 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1522 
  1523 
  1524 *** FOL and ZF ***
  1525 
  1526 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1527   with `addloop' of the simplifier to faciliate case splitting in premises.
  1528 
  1529 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1530 in HOL, they strip ALL and --> from proved theorems;
  1531 
  1532 
  1533 
  1534 New in Isabelle94-8 (May 1997)
  1535 ------------------------------
  1536 
  1537 *** General Changes ***
  1538 
  1539 * new utilities to build / run / maintain Isabelle etc. (in parts
  1540 still somewhat experimental); old Makefiles etc. still functional;
  1541 
  1542 * new 'Isabelle System Manual';
  1543 
  1544 * INSTALL text, together with ./configure and ./build scripts;
  1545 
  1546 * reimplemented type inference for greater efficiency, better error
  1547 messages and clean internal interface;
  1548 
  1549 * prlim command for dealing with lots of subgoals (an easier way of
  1550 setting goals_limit);
  1551 
  1552 
  1553 *** Syntax ***
  1554 
  1555 * supports alternative (named) syntax tables (parser and pretty
  1556 printer); internal interface is provided by add_modesyntax(_i);
  1557 
  1558 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1559 be used in conjunction with the Isabelle symbol font; uses the
  1560 "symbols" syntax table;
  1561 
  1562 * added token_translation interface (may translate name tokens in
  1563 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1564 the current print_mode); IMPORTANT: user print translation functions
  1565 are responsible for marking newly introduced bounds
  1566 (Syntax.mark_boundT);
  1567 
  1568 * token translations for modes "xterm" and "xterm_color" that display
  1569 names in bold, underline etc. or colors (which requires a color
  1570 version of xterm);
  1571 
  1572 * infixes may now be declared with names independent of their syntax;
  1573 
  1574 * added typed_print_translation (like print_translation, but may
  1575 access type of constant);
  1576 
  1577 
  1578 *** Classical Reasoner ***
  1579 
  1580 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  1581 some limitations.  Blast_tac...
  1582   + ignores addss, addbefore, addafter; this restriction is intrinsic
  1583   + ignores elimination rules that don't have the correct format
  1584         (the conclusion MUST be a formula variable)
  1585   + ignores types, which can make HOL proofs fail
  1586   + rules must not require higher-order unification, e.g. apply_type in ZF
  1587     [message "Function Var's argument not a bound variable" relates to this]
  1588   + its proof strategy is more general but can actually be slower
  1589 
  1590 * substitution with equality assumptions no longer permutes other
  1591 assumptions;
  1592 
  1593 * minor changes in semantics of addafter (now called addaltern); renamed
  1594 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  1595 (and access functions for it);
  1596 
  1597 * improved combination of classical reasoner and simplifier:
  1598   + functions for handling clasimpsets
  1599   + improvement of addss: now the simplifier is called _after_ the
  1600     safe steps.
  1601   + safe variant of addss called addSss: uses safe simplifications
  1602     _during_ the safe steps. It is more complete as it allows multiple
  1603     instantiations of unknowns (e.g. with slow_tac).
  1604 
  1605 *** Simplifier ***
  1606 
  1607 * added interface for simplification procedures (functions that
  1608 produce *proven* rewrite rules on the fly, depending on current
  1609 redex);
  1610 
  1611 * ordering on terms as parameter (used for ordered rewriting);
  1612 
  1613 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  1614 
  1615 * the solver is now split into a safe and an unsafe part.
  1616 This should be invisible for the normal user, except that the
  1617 functions setsolver and addsolver have been renamed to setSolver and
  1618 addSolver; added safe_asm_full_simp_tac;
  1619 
  1620 
  1621 *** HOL ***
  1622 
  1623 * a generic induction tactic `induct_tac' which works for all datatypes and
  1624 also for type `nat';
  1625 
  1626 * a generic case distinction tactic `exhaust_tac' which works for all
  1627 datatypes and also for type `nat';
  1628 
  1629 * each datatype comes with a function `size';
  1630 
  1631 * patterns in case expressions allow tuple patterns as arguments to
  1632 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1633 
  1634 * primrec now also works with type nat;
  1635 
  1636 * recdef: a new declaration form, allows general recursive functions to be
  1637 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1638 
  1639 * the constant for negation has been renamed from "not" to "Not" to
  1640 harmonize with FOL, ZF, LK, etc.;
  1641 
  1642 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1643 infinite lists;
  1644 
  1645 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1646 
  1647 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1648 problems in commutative rings, using axiomatic type classes for + and *;
  1649 
  1650 * more examples in HOL/MiniML and HOL/Auth;
  1651 
  1652 * more default rewrite rules for quantifiers, union/intersection;
  1653 
  1654 * a new constant `arbitrary == @x.False';
  1655 
  1656 * HOLCF/IOA replaces old HOL/IOA;
  1657 
  1658 * HOLCF changes: derived all rules and arities
  1659   + axiomatic type classes instead of classes
  1660   + typedef instead of faking type definitions
  1661   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1662   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1663   + eliminated the types void, one, tr
  1664   + use unit lift and bool lift (with translations) instead of one and tr
  1665   + eliminated blift from Lift3.thy (use Def instead of blift)
  1666   all eliminated rules are derived as theorems --> no visible changes ;
  1667 
  1668 
  1669 *** ZF ***
  1670 
  1671 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1672 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1673 as ZF_cs addSIs [equalityI];
  1674 
  1675 
  1676 
  1677 New in Isabelle94-7 (November 96)
  1678 ---------------------------------
  1679 
  1680 * allowing negative levels (as offsets) in prlev and choplev;
  1681 
  1682 * super-linear speedup for large simplifications;
  1683 
  1684 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1685 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1686 FAIL); can suppress it using the command Delsimps (ex_simps @
  1687 all_simps); De Morgan laws are also now included, by default;
  1688 
  1689 * improved printing of ==>  :  ~:
  1690 
  1691 * new object-logic "Sequents" adds linear logic, while replacing LK
  1692 and Modal (thanks to Sara Kalvala);
  1693 
  1694 * HOL/Auth: correctness proofs for authentication protocols;
  1695 
  1696 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1697 examples on HOL/Auth);
  1698 
  1699 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1700 the rewriter and classical reasoner simultaneously;
  1701 
  1702 * function uresult no longer returns theorems in "standard" format;
  1703 regain previous version by: val uresult = standard o uresult;
  1704 
  1705 
  1706 
  1707 New in Isabelle94-6
  1708 -------------------
  1709 
  1710 * oracles -- these establish an interface between Isabelle and trusted
  1711 external reasoners, which may deliver results as theorems;
  1712 
  1713 * proof objects (in particular record all uses of oracles);
  1714 
  1715 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1716 
  1717 * "constdefs" section in theory files;
  1718 
  1719 * "primrec" section (HOL) no longer requires names;
  1720 
  1721 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1722 
  1723 
  1724 
  1725 New in Isabelle94-5
  1726 -------------------
  1727 
  1728 * reduced space requirements;
  1729 
  1730 * automatic HTML generation from theories;
  1731 
  1732 * theory files no longer require "..." (quotes) around most types;
  1733 
  1734 * new examples, including two proofs of the Church-Rosser theorem;
  1735 
  1736 * non-curried (1994) version of HOL is no longer distributed;
  1737 
  1738 
  1739 
  1740 New in Isabelle94-4
  1741 -------------------
  1742 
  1743 * greatly reduced space requirements;
  1744 
  1745 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1746 
  1747 * searchable theorem database (see the section "Retrieving theorems" on
  1748 page 8 of the Reference Manual);
  1749 
  1750 * new examples, including Grabczewski's monumental case study of the
  1751 Axiom of Choice;
  1752 
  1753 * The previous version of HOL renamed to Old_HOL;
  1754 
  1755 * The new version of HOL (previously called CHOL) uses a curried syntax
  1756 for functions.  Application looks like f a b instead of f(a,b);
  1757 
  1758 * Mutually recursive inductive definitions finally work in HOL;
  1759 
  1760 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1761 translates to the operator "split";
  1762 
  1763 
  1764 
  1765 New in Isabelle94-3
  1766 -------------------
  1767 
  1768 * new infix operator, addss, allowing the classical reasoner to
  1769 perform simplification at each step of its search.  Example:
  1770         fast_tac (cs addss ss)
  1771 
  1772 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1773 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1774 look like (a,b) instead of <a,b>;
  1775 
  1776 * PLEASE NOTE: CHOL will eventually replace HOL!
  1777 
  1778 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1779 It translates to the operator "split".  A new theory of integers is available;
  1780 
  1781 * In ZF, integer numerals now denote two's-complement binary integers.
  1782 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1783 
  1784 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1785 of the Axiom of Choice;
  1786 
  1787 
  1788 
  1789 New in Isabelle94-2
  1790 -------------------
  1791 
  1792 * Significantly faster resolution;
  1793 
  1794 * the different sections in a .thy file can now be mixed and repeated
  1795 freely;
  1796 
  1797 * Database of theorems for FOL, HOL and ZF.  New
  1798 commands including qed, qed_goal and bind_thm store theorems in the database.
  1799 
  1800 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1801 a given theory (thms_of), or find out what theory a theorem was proved in
  1802 (theory_of_thm);
  1803 
  1804 * Bugs fixed in the inductive definition and datatype packages;
  1805 
  1806 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1807 and HOL_dup_cs obsolete;
  1808 
  1809 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1810 have been removed;
  1811 
  1812 * Simpler definition of function space in ZF;
  1813 
  1814 * new results about cardinal and ordinal arithmetic in ZF;
  1815 
  1816 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1817 types;
  1818 
  1819 
  1820 $Id$