NEWS
author nipkow
Sat Jan 06 10:36:19 2001 +0100 (2001-01-06)
changeset 10799 ea69ee7e117b
parent 10793 4d6cf7702e3c
child 10856 e8a5340418b6
permissions -rw-r--r--
*** empty log message ***
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 *** Overview of INCOMPATIBILITIES ***
     5 
     6 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
     7 function;
     8 
     9 * HOL: induct renamed to lfp_induct;
    10 
    11 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
    12 
    13 * HOL: infix "dvd" now has priority 50 rather than 70
    14   (because it is a relation)
    15   infix ^^ has been renamed ```
    16   "univalent" has been renamed "single_valued"
    17 
    18 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
    19 
    20 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
    21 consequence, it is no longer monotonic wrt. the local goal context
    22 (which is now passed through the inductive cases);
    23 
    24 
    25 *** Document preparation ***
    26 
    27 * improved isabelle style files; more abstract symbol implementation
    28 (should now use \isamath{...} and \isatext{...} in custom symbol
    29 definitions);
    30 
    31 * support sub/super scripts (for single symbols only), input syntax is
    32 like this: "A\<^sup>*" or "A\<^sup>\<star>";
    33 
    34 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
    35 state; Note that presentation of goal states does not conform to
    36 actual human-readable proof documents.  Please do not include goal
    37 states into document output unless you really know what you are doing!
    38 
    39 
    40 *** Isar ***
    41 
    42 * Pure: Isar now suffers initial goal statements to contain unbound
    43 schematic variables (this does not conform to actual readable proof
    44 documents, due to unpredictable outcome and non-compositional proof
    45 checking); users who know what they are doing may use schematic goals
    46 for Prolog-style synthesis of proven results;
    47 
    48 * Pure: assumption method (an implicit finishing) now handles actual
    49 rules as well;
    50 
    51 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
    52 initial goal, declare "that" only as Pure intro (only for single
    53 steps); the "that" rule assumption may now be involved in implicit
    54 finishing, thus ".." becomes a feasible for trivial obtains;
    55 
    56 * Pure: default proof step now includes 'intro_classes'; thus trivial
    57 instance proofs may be performed by "..";
    58 
    59 * Pure: ?thesis / ?this / "..." now work for pure meta-level
    60 statements as well;
    61 
    62 * HOL: improved method 'induct' --- now handles non-atomic goals
    63 (potential INCOMPATIBILITY); tuned error handling;
    64 
    65 * HOL: cases and induct rules now provide explicit hints about the
    66 number of facts to be consumed (0 for "type" and 1 for "set" rules);
    67 any remaining facts are inserted into the goal verbatim;
    68 
    69 * HOL: added 'recdef_tc' command;
    70 
    71 
    72 *** HOL ***
    73 
    74 * HOL/Library: a collection of generic theories to be used together
    75 with main HOL; the theory loader path already includes this directory
    76 by default; the following existing theories have been moved here:
    77 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
    78 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
    79 
    80 * HOL basics: added overloaded operations "inverse" and "divide"
    81 (infix "/"), syntax for generic "abs" operation, generic summation
    82 operator;
    83 
    84 * HOL/typedef: simplified package, provide more useful rules (see also
    85 HOL/subset.thy);
    86 
    87 * HOL-Hyperreal: a new target, extending HOL-Real with the hyperreals and 
    88 Fleuriot's mechanization of analysis;
    89 
    90 * HOL-Real, HOL-Hyperreals: improved arithmetic simplification;
    91 
    92 *** CTT ***
    93 
    94 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
    95 "lam" is displayed as TWO lambda-symbols
    96 
    97 * CTT: theory Main now available, containing everything (that is, Bool
    98 and Arith);
    99 
   100 
   101 *** General ***
   102 
   103 * print modes "brackets" and "no_brackets" control output of nested =>
   104 (types) and ==> (props); the default behaviour is "brackets";
   105 
   106 * system: support Poly/ML 4.0 (current beta versions);
   107 
   108 * Pure: the Simplifier has been implemented properly as a derived rule
   109 outside of the actual kernel (at last!); the overall performance
   110 penalty in practical applications is about 50%, while reliability of
   111 the Isabelle inference kernel has been greatly improved;
   112 
   113 * Provers: fast_tac (and friends) now handle actual object-logic rules
   114 as assumptions as well;
   115 
   116 
   117 
   118 New in Isabelle99-1 (October 2000)
   119 ----------------------------------
   120 
   121 *** Overview of INCOMPATIBILITIES ***
   122 
   123 * HOL: simplification of natural numbers is much changed; to partly
   124 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   125 issue the following ML commands:
   126 
   127   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   128   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   129 
   130 * HOL: simplification no longer dives into case-expressions; this is
   131 controlled by "t.weak_case_cong" for each datatype t;
   132 
   133 * HOL: nat_less_induct renamed to less_induct;
   134 
   135 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   136 fixsome to patch .thy and .ML sources automatically;
   137 
   138   select_equality  -> some_equality
   139   select_eq_Ex     -> some_eq_ex
   140   selectI2EX       -> someI2_ex
   141   selectI2         -> someI2
   142   selectI          -> someI
   143   select1_equality -> some1_equality
   144   Eps_sym_eq       -> some_sym_eq_trivial
   145   Eps_eq           -> some_eq_trivial
   146 
   147 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   148 
   149 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   150 instead);
   151 
   152 * HOL: the recursion equations generated by 'recdef' are now called
   153 f.simps instead of f.rules;
   154 
   155 * HOL: qed_spec_mp now also handles bounded ALL as well;
   156 
   157 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   158 sometimes be needed;
   159 
   160 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   161 
   162 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   163 
   164 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   165 product is now "<*>" instead of "Times"; the lexicographic product is
   166 now "<*lex*>" instead of "**";
   167 
   168 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   169 of main HOL, but was unused); better use HOL's datatype package;
   170 
   171 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   172 the old syntax may be recovered as follows:
   173 
   174   syntax (symbols)
   175     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   176       (infixl "\\<oplus>" 100)
   177 
   178 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   179 
   180 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   181 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   182 internally;
   183 
   184 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   185 changed from A/r to A//r;
   186 
   187 * ZF: new treatment of arithmetic (nat & int) may break some old
   188 proofs;
   189 
   190 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   191 rulify -> rule_format, elimify -> elim_format, ...);
   192 
   193 * Isar/Provers: intro/elim/dest attributes changed; renamed
   194 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   195 should have to change intro!! to intro? only); replaced "delrule" by
   196 "rule del";
   197 
   198 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   199 
   200 * Provers: strengthened force_tac by using new first_best_tac;
   201 
   202 * LaTeX document preparation: several changes of isabelle.sty (see
   203 lib/texinputs);
   204 
   205 
   206 *** Document preparation ***
   207 
   208 * formal comments (text blocks etc.) in new-style theories may now
   209 contain antiquotations of thm/prop/term/typ/text to be presented
   210 according to latex print mode; concrete syntax is like this:
   211 @{term[show_types] "f(x) = a + x"};
   212 
   213 * isatool mkdir provides easy setup of Isabelle session directories,
   214 including proper document sources;
   215 
   216 * generated LaTeX sources are now deleted after successful run
   217 (isatool document -c); may retain a copy somewhere else via -D option
   218 of isatool usedir;
   219 
   220 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   221 style files, achieving self-contained LaTeX sources and simplifying
   222 LaTeX debugging;
   223 
   224 * old-style theories now produce (crude) LaTeX output as well;
   225 
   226 * browser info session directories are now self-contained (may be put
   227 on WWW server seperately); improved graphs of nested sessions; removed
   228 graph for 'all sessions';
   229 
   230 * several improvements in isabelle style files; \isabellestyle{it}
   231 produces fake math mode output; \isamarkupheader is now \section by
   232 default; see lib/texinputs/isabelle.sty etc.;
   233 
   234 
   235 *** Isar ***
   236 
   237 * Isar/Pure: local results and corresponding term bindings are now
   238 subject to Hindley-Milner polymorphism (similar to ML); this
   239 accommodates incremental type-inference very nicely;
   240 
   241 * Isar/Pure: new derived language element 'obtain' supports
   242 generalized existence reasoning;
   243 
   244 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   245 support accumulation of results, without applying any rules yet;
   246 useful to collect intermediate results without explicit name
   247 references, and for use with transitivity rules with more than 2
   248 premises;
   249 
   250 * Isar/Pure: scalable support for case-analysis type proofs: new
   251 'case' language element refers to local contexts symbolically, as
   252 produced by certain proof methods; internally, case names are attached
   253 to theorems as "tags";
   254 
   255 * Isar/Pure: theory command 'hide' removes declarations from
   256 class/type/const name spaces;
   257 
   258 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   259 indicate potential overloading;
   260 
   261 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   262 
   263 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   264 "{a,b,c}" instead of {a,b,c};
   265 
   266 * Isar/Pure now provides its own version of intro/elim/dest
   267 attributes; useful for building new logics, but beware of confusion
   268 with the version in Provers/classical;
   269 
   270 * Isar/Pure: the local context of (non-atomic) goals is provided via
   271 case name 'antecedent';
   272 
   273 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   274 to the current context is now done automatically);
   275 
   276 * Isar/Pure: theory command 'method_setup' provides a simple interface
   277 for definining proof methods in ML;
   278 
   279 * Isar/Provers: intro/elim/dest attributes changed; renamed
   280 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   281 most cases, one should have to change intro!! to intro? only);
   282 replaced "delrule" by "rule del";
   283 
   284 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   285 'symmetric' attribute (the latter supercedes [RS sym]);
   286 
   287 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   288 method modifier); 'simp' method: 'only:' modifier removes loopers as
   289 well (including splits);
   290 
   291 * Isar/Provers: Simplifier and Classical methods now support all kind
   292 of modifiers used in the past, including 'cong', 'iff', etc.
   293 
   294 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   295 of Simplifier and Classical reasoner);
   296 
   297 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   298 now support named cases; major packages (inductive, datatype, primrec,
   299 recdef) support case names and properly name parameters;
   300 
   301 * Isar/HOL: new transitivity rules for substitution in inequalities --
   302 monotonicity conditions are extracted to be proven at end of
   303 calculations;
   304 
   305 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   306 method anyway;
   307 
   308 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   309 split_if split_if_asm; datatype package provides theorems foo.splits =
   310 foo.split foo.split_asm for each datatype;
   311 
   312 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   313 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   314 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   315 use "(cases (simplified))" method in proper proof texts);
   316 
   317 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   318 
   319 * Isar: names of theorems etc. may be natural numbers as well;
   320 
   321 * Isar: 'pr' command: optional arguments for goals_limit and
   322 ProofContext.prems_limit; no longer prints theory contexts, but only
   323 proof states;
   324 
   325 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   326 additional print modes to be specified; e.g. "pr(latex)" will print
   327 proof state according to the Isabelle LaTeX style;
   328 
   329 * Isar: improved support for emulating tactic scripts, including proof
   330 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   331 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   332 (for HOL datatypes);
   333 
   334 * Isar: simplified (more robust) goal selection of proof methods: 1st
   335 goal, all goals, or explicit goal specifier (tactic emulation); thus
   336 'proof method scripts' have to be in depth-first order;
   337 
   338 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   339 
   340 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   341 should instead use individual commands for printing items
   342 (print_commands, print_methods etc.);
   343 
   344 * Isar: added 'nothing' --- the empty list of theorems;
   345 
   346 
   347 *** HOL ***
   348 
   349 * HOL/MicroJava: formalization of a fragment of Java, together with a
   350 corresponding virtual machine and a specification of its bytecode
   351 verifier and a lightweight bytecode verifier, including proofs of
   352 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   353 Cornelia Pusch (see also the homepage of project Bali at
   354 http://isabelle.in.tum.de/Bali/);
   355 
   356 * HOL/Algebra: new theory of rings and univariate polynomials, by
   357 Clemens Ballarin;
   358 
   359 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   360 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   361 Rasmussen;
   362 
   363 * HOL/Lattice: fundamental concepts of lattice theory and order
   364 structures, including duals, properties of bounds versus algebraic
   365 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   366 Theorem for complete lattices etc.; may also serve as a demonstration
   367 for abstract algebraic reasoning using axiomatic type classes, and
   368 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   369 
   370 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   371 von Oheimb;
   372 
   373 * HOL/IMPP: extension of IMP with local variables and mutually
   374 recursive procedures, by David von Oheimb;
   375 
   376 * HOL/Lambda: converted into new-style theory and document;
   377 
   378 * HOL/ex/Multiquote: example of multiple nested quotations and
   379 anti-quotations -- basically a generalized version of de-Bruijn
   380 representation; very useful in avoiding lifting of operations;
   381 
   382 * HOL/record: added general record equality rule to simpset; fixed
   383 select-update simplification procedure to handle extended records as
   384 well; admit "r" as field name;
   385 
   386 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   387 other numeric types and also as the identity of groups, rings, etc.;
   388 
   389 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   390 Types nat and int belong to this axclass;
   391 
   392 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   393    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   394    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   395   two terms #m*u and #n*u are replaced by #(m+n)*u
   396     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   397   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   398     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   399 
   400 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   401 powerful prover for predicate logic but knows nothing of clasets; see
   402 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   403 
   404 * HOL: new version of "case_tac" subsumes both boolean case split and
   405 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   406 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   407 
   408 * HOL: simplification no longer dives into case-expressions: only the
   409 selector expression is simplified, but not the remaining arms; to
   410 enable full simplification of case-expressions for datatype t, you may
   411 remove t.weak_case_cong from the simpset, either globally (Delcongs
   412 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   413 
   414 * HOL/recdef: the recursion equations generated by 'recdef' for
   415 function 'f' are now called f.simps instead of f.rules; if all
   416 termination conditions are proved automatically, these simplification
   417 rules are added to the simpset, as in primrec; rules may be named
   418 individually as well, resulting in a separate list of theorems for
   419 each equation;
   420 
   421 * HOL/While is a new theory that provides a while-combinator. It
   422 permits the definition of tail-recursive functions without the
   423 provision of a termination measure. The latter is necessary once the
   424 invariant proof rule for while is applied.
   425 
   426 * HOL: new (overloaded) notation for the set of elements below/above
   427 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   428 
   429 * HOL: theorems impI, allI, ballI bound as "strip";
   430 
   431 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   432 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   433 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   434 
   435 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   436 
   437 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   438 main HOL, but was unused);
   439 
   440 * HOL: fewer consts declared as global (e.g. have to refer to
   441 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   442 
   443 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   444 in case of overlap with user translations (e.g. judgements over
   445 tuples); (note that the underlying logical represenation is still
   446 bogus);
   447 
   448 
   449 *** ZF ***
   450 
   451 * ZF: simplification automatically cancels common terms in arithmetic
   452 expressions over nat and int;
   453 
   454 * ZF: new treatment of nat to minimize type-checking: all operators
   455 coerce their operands to a natural number using the function natify,
   456 making the algebraic laws unconditional;
   457 
   458 * ZF: as above, for int: operators coerce their operands to an integer
   459 using the function intify;
   460 
   461 * ZF: the integer library now contains many of the usual laws for the
   462 orderings, including $<=, and monotonicity laws for $+ and $*;
   463 
   464 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
   465 simplification;
   466 
   467 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
   468 to the simplifier and classical reasoner simultaneously;
   469 
   470 
   471 *** General ***
   472 
   473 * Provers: blast_tac now handles actual object-logic rules as
   474 assumptions; note that auto_tac uses blast_tac internally as well;
   475 
   476 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
   477 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
   478 
   479 * Provers: delrules now handles destruct rules as well (no longer need
   480 explicit make_elim);
   481 
   482 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
   483   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   484 use instead the strong form,
   485   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   486 in HOL, FOL and ZF the function cla_make_elim will create such rules
   487 from destruct-rules;
   488 
   489 * Provers: Simplifier.easy_setup provides a fast path to basic
   490 Simplifier setup for new object-logics;
   491 
   492 * Pure: AST translation rules no longer require constant head on LHS;
   493 
   494 * Pure: improved name spaces: ambiguous output is qualified; support
   495 for hiding of names;
   496 
   497 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
   498 XSYMBOL_HOME; no longer need to do manual configuration in most
   499 situations;
   500 
   501 * system: compression of ML heaps images may now be controlled via -c
   502 option of isabelle and isatool usedir (currently only observed by
   503 Poly/ML);
   504 
   505 * system: isatool installfonts may handle X-Symbol fonts as well (very
   506 useful for remote X11);
   507 
   508 * system: provide TAGS file for Isabelle sources;
   509 
   510 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
   511 order;
   512 
   513 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
   514 timing flag supersedes proof_timing and Toplevel.trace;
   515 
   516 * ML: new combinators |>> and |>>> for incremental transformations
   517 with secondary results (e.g. certain theory extensions):
   518 
   519 * ML: PureThy.add_defs gets additional argument to indicate potential
   520 overloading (usually false);
   521 
   522 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
   523 results;
   524 
   525 
   526 
   527 New in Isabelle99 (October 1999)
   528 --------------------------------
   529 
   530 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   531 
   532 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
   533 are no longer simplified.  (This allows the simplifier to unfold recursive
   534 functional programs.)  To restore the old behaviour, declare
   535 
   536     Delcongs [if_weak_cong];
   537 
   538 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
   539 complement;
   540 
   541 * HOL: the predicate "inj" is now defined by translation to "inj_on";
   542 
   543 * HOL/datatype: mutual_induct_tac no longer exists --
   544   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
   545 
   546 * HOL/typedef: fixed type inference for representing set; type
   547 arguments now have to occur explicitly on the rhs as type constraints;
   548 
   549 * ZF: The con_defs part of an inductive definition may no longer refer
   550 to constants declared in the same theory;
   551 
   552 * HOL, ZF: the function mk_cases, generated by the inductive
   553 definition package, has lost an argument.  To simplify its result, it
   554 uses the default simpset instead of a supplied list of theorems.
   555 
   556 * HOL/List: the constructors of type list are now Nil and Cons;
   557 
   558 * Simplifier: the type of the infix ML functions
   559         setSSolver addSSolver setSolver addSolver
   560 is now  simpset * solver -> simpset  where `solver' is a new abstract type
   561 for packaging solvers. A solver is created via
   562         mk_solver: string -> (thm list -> int -> tactic) -> solver
   563 where the string argument is only a comment.
   564 
   565 
   566 *** Proof tools ***
   567 
   568 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
   569 decision procedure for linear arithmetic. Currently it is used for
   570 types `nat', `int', and `real' in HOL (see below); it can, should and
   571 will be instantiated for other types and logics as well.
   572 
   573 * The simplifier now accepts rewrite rules with flexible heads, eg
   574      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
   575   They are applied like any rule with a non-pattern lhs, i.e. by first-order
   576   matching.
   577 
   578 
   579 *** General ***
   580 
   581 * New Isabelle/Isar subsystem provides an alternative to traditional
   582 tactical theorem proving; together with the ProofGeneral/isar user
   583 interface it offers an interactive environment for developing human
   584 readable proof documents (Isar == Intelligible semi-automated
   585 reasoning); for further information see isatool doc isar-ref,
   586 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
   587 
   588 * improved and simplified presentation of theories: better HTML markup
   589 (including colors), graph views in several sizes; isatool usedir now
   590 provides a proper interface for user theories (via -P option); actual
   591 document preparation based on (PDF)LaTeX is available as well (for
   592 new-style theories only); see isatool doc system for more information;
   593 
   594 * native support for Proof General, both for classic Isabelle and
   595 Isabelle/Isar;
   596 
   597 * ML function thm_deps visualizes dependencies of theorems and lemmas,
   598 using the graph browser tool;
   599 
   600 * Isabelle manuals now also available as PDF;
   601 
   602 * theory loader rewritten from scratch (may not be fully
   603 bug-compatible); old loadpath variable has been replaced by show_path,
   604 add_path, del_path, reset_path functions; new operations such as
   605 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
   606 isatool doc ref);
   607 
   608 * improved isatool install: option -k creates KDE application icon,
   609 option -p DIR installs standalone binaries;
   610 
   611 * added ML_PLATFORM setting (useful for cross-platform installations);
   612 more robust handling of platform specific ML images for SML/NJ;
   613 
   614 * the settings environment is now statically scoped, i.e. it is never
   615 created again in sub-processes invoked from isabelle, isatool, or
   616 Isabelle;
   617 
   618 * path element specification '~~' refers to '$ISABELLE_HOME';
   619 
   620 * in locales, the "assumes" and "defines" parts may be omitted if
   621 empty;
   622 
   623 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   624 long arrows);
   625 
   626 * new print_mode "HTML";
   627 
   628 * new flag show_tags controls display of tags of theorems (which are
   629 basically just comments that may be attached by some tools);
   630 
   631 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   632 mode and goal output format:
   633 
   634 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   635 244c244
   636 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   637 ---
   638 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   639 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   640 181c181
   641 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   642 ---
   643 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   644 
   645 * function bind_thms stores lists of theorems (cf. bind_thm);
   646 
   647 * new shorthand tactics ftac, eatac, datac, fatac;
   648 
   649 * qed (and friends) now accept "" as result name; in that case the
   650 theorem is not stored, but proper checks and presentation of the
   651 result still apply;
   652 
   653 * theorem database now also indexes constants "Trueprop", "all",
   654 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   655 
   656 
   657 *** HOL ***
   658 
   659 ** HOL arithmetic **
   660 
   661 * There are now decision procedures for linear arithmetic over nat and
   662 int:
   663 
   664 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   665 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   666 are treated as atomic; subformulae not involving type `nat' or `int'
   667 are ignored; quantified subformulae are ignored unless they are
   668 positive universal or negative existential. The tactic has to be
   669 invoked by hand and can be a little bit slow. In particular, the
   670 running time is exponential in the number of occurrences of `min' and
   671 `max', and `-' on `nat'.
   672 
   673 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   674 (negated) (in)equalities among the premises and the conclusion into
   675 account (i.e. no compound formulae) and does not know about `min' and
   676 `max', and `-' on `nat'. It is fast and is used automatically by the
   677 simplifier.
   678 
   679 NB: At the moment, these decision procedures do not cope with mixed
   680 nat/int formulae where the two parts interact, such as `m < n ==>
   681 int(m) < int(n)'.
   682 
   683 * HOL/Numeral provides a generic theory of numerals (encoded
   684 efficiently as bit strings); setup for types nat/int/real is in place;
   685 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   686 int, existing theories and proof scripts may require a few additional
   687 type constraints;
   688 
   689 * integer division and remainder can now be performed on constant
   690 arguments;
   691 
   692 * many properties of integer multiplication, division and remainder
   693 are now available;
   694 
   695 * An interface to the Stanford Validity Checker (SVC) is available through the
   696 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   697 are proved automatically.  SVC must be installed separately, and its results
   698 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   699 invocation of the underlying oracle).  For SVC see
   700   http://verify.stanford.edu/SVC
   701 
   702 * IsaMakefile: the HOL-Real target now builds an actual image;
   703 
   704 
   705 ** HOL misc **
   706 
   707 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   708 (in Isabelle/Isar) -- by Gertrud Bauer;
   709 
   710 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   711 analysis for assembly languages with subtypes;
   712 
   713 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   714 -- avoids syntactic ambiguities and treats state, transition, and
   715 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   716 changed syntax and (many) tactics;
   717 
   718 * HOL/inductive: Now also handles more general introduction rules such
   719   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
   720   theorems are now maintained within the theory (maintained via the
   721   "mono" attribute);
   722 
   723 * HOL/datatype: Now also handles arbitrarily branching datatypes
   724   (using function types) such as
   725 
   726   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
   727 
   728 * HOL/record: record_simproc (part of the default simpset) takes care
   729 of selectors applied to updated records; record_split_tac is no longer
   730 part of the default claset; update_defs may now be removed from the
   731 simpset in many cases; COMPATIBILITY: old behavior achieved by
   732 
   733   claset_ref () := claset() addSWrapper record_split_wrapper;
   734   Delsimprocs [record_simproc]
   735 
   736 * HOL/typedef: fixed type inference for representing set; type
   737 arguments now have to occur explicitly on the rhs as type constraints;
   738 
   739 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
   740 names rather than an ML expression;
   741 
   742 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
   743 supplied later.  Program schemes can be defined, such as
   744     "While B C s = (if B s then While B C (C s) else s)"
   745 where the well-founded relation can be chosen after B and C have been given.
   746 
   747 * HOL/List: the constructors of type list are now Nil and Cons;
   748 INCOMPATIBILITY: while [] and infix # syntax is still there, of
   749 course, ML tools referring to List.list.op # etc. have to be adapted;
   750 
   751 * HOL_quantifiers flag superseded by "HOL" print mode, which is
   752 disabled by default; run isabelle with option -m HOL to get back to
   753 the original Gordon/HOL-style output;
   754 
   755 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
   756 ALL x<=y. P, EX x<y. P, EX x<=y. P;
   757 
   758 * HOL basic syntax simplified (more orthogonal): all variants of
   759 All/Ex now support plain / symbolic / HOL notation; plain syntax for
   760 Eps operator is provided as well: "SOME x. P[x]";
   761 
   762 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
   763 
   764 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
   765 thus available for user theories;
   766 
   767 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
   768 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
   769 time;
   770 
   771 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
   772 several times and then mp;
   773 
   774 
   775 *** LK ***
   776 
   777 * the notation <<...>> is now available as a notation for sequences of
   778 formulas;
   779 
   780 * the simplifier is now installed
   781 
   782 * the axiom system has been generalized (thanks to Soren Heilmann)
   783 
   784 * the classical reasoner now has a default rule database
   785 
   786 
   787 *** ZF ***
   788 
   789 * new primrec section allows primitive recursive functions to be given
   790 directly (as in HOL) over datatypes and the natural numbers;
   791 
   792 * new tactics induct_tac and exhaust_tac for induction (or case
   793 analysis) over datatypes and the natural numbers;
   794 
   795 * the datatype declaration of type T now defines the recursor T_rec;
   796 
   797 * simplification automatically does freeness reasoning for datatype
   798 constructors;
   799 
   800 * automatic type-inference, with AddTCs command to insert new
   801 type-checking rules;
   802 
   803 * datatype introduction rules are now added as Safe Introduction rules
   804 to the claset;
   805 
   806 * the syntax "if P then x else y" is now available in addition to
   807 if(P,x,y);
   808 
   809 
   810 *** Internal programming interfaces ***
   811 
   812 * tuned simplifier trace output; new flag debug_simp;
   813 
   814 * structures Vartab / Termtab (instances of TableFun) offer efficient
   815 tables indexed by indexname_ord / term_ord (compatible with aconv);
   816 
   817 * AxClass.axclass_tac lost the theory argument;
   818 
   819 * tuned current_goals_markers semantics: begin / end goal avoids
   820 printing empty lines;
   821 
   822 * removed prs and prs_fn hook, which was broken because it did not
   823 include \n in its semantics, forcing writeln to add one
   824 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
   825 string -> unit if you really want to output text without newline;
   826 
   827 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
   828 plain output, interface builders may have to enable 'isabelle_font'
   829 mode to get Isabelle font glyphs as before;
   830 
   831 * refined token_translation interface; INCOMPATIBILITY: output length
   832 now of type real instead of int;
   833 
   834 * theory loader actions may be traced via new ThyInfo.add_hook
   835 interface (see src/Pure/Thy/thy_info.ML); example application: keep
   836 your own database of information attached to *whole* theories -- as
   837 opposed to intra-theory data slots offered via TheoryDataFun;
   838 
   839 * proper handling of dangling sort hypotheses (at last!);
   840 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
   841 extra sort hypotheses that can be witnessed from the type signature;
   842 the force_strip_shyps flag is gone, any remaining shyps are simply
   843 left in the theorem (with a warning issued by strip_shyps_warning);
   844 
   845 
   846 
   847 New in Isabelle98-1 (October 1998)
   848 ----------------------------------
   849 
   850 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   851 
   852 * several changes of automated proof tools;
   853 
   854 * HOL: major changes to the inductive and datatype packages, including
   855 some minor incompatibilities of theory syntax;
   856 
   857 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
   858 called `inj_on';
   859 
   860 * HOL: removed duplicate thms in Arith:
   861   less_imp_add_less  should be replaced by  trans_less_add1
   862   le_imp_add_le      should be replaced by  trans_le_add1
   863 
   864 * HOL: unary minus is now overloaded (new type constraints may be
   865 required);
   866 
   867 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
   868 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
   869 now taken as an integer constant.
   870 
   871 * Pure: ML function 'theory_of' renamed to 'theory';
   872 
   873 
   874 *** Proof tools ***
   875 
   876 * Simplifier:
   877   1. Asm_full_simp_tac is now more aggressive.
   878      1. It will sometimes reorient premises if that increases their power to
   879         simplify.
   880      2. It does no longer proceed strictly from left to right but may also
   881         rotate premises to achieve further simplification.
   882      For compatibility reasons there is now Asm_lr_simp_tac which is like the
   883      old Asm_full_simp_tac in that it does not rotate premises.
   884   2. The simplifier now knows a little bit about nat-arithmetic.
   885 
   886 * Classical reasoner: wrapper mechanism for the classical reasoner now
   887 allows for selected deletion of wrappers, by introduction of names for
   888 wrapper functionals.  This implies that addbefore, addSbefore,
   889 addaltern, and addSaltern now take a pair (name, tactic) as argument,
   890 and that adding two tactics with the same name overwrites the first
   891 one (emitting a warning).
   892   type wrapper = (int -> tactic) -> (int -> tactic)
   893   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
   894   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
   895   delWrapper, delSWrapper: claset *  string            -> claset
   896   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
   897 
   898 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
   899 semantics; addbefore now affects only the unsafe part of step_tac
   900 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
   901 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
   902 by Force_tac;
   903 
   904 * Classical reasoner: setwrapper to setWrapper and compwrapper to
   905 compWrapper; added safe wrapper (and access functions for it);
   906 
   907 * HOL/split_all_tac is now much faster and fails if there is nothing
   908 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
   909 and the names of the automatically generated variables have changed.
   910 split_all_tac has moved within claset() from unsafe wrappers to safe
   911 wrappers, which means that !!-bound variables are split much more
   912 aggressively, and safe_tac and clarify_tac now split such variables.
   913 If this splitting is not appropriate, use delSWrapper "split_all_tac".
   914 Note: the same holds for record_split_tac, which does the job of
   915 split_all_tac for record fields.
   916 
   917 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
   918 permanently to the default simpset using Addsplits just like
   919 Addsimps. They can be removed via Delsplits just like
   920 Delsimps. Lower-case versions are also available.
   921 
   922 * HOL/Simplifier: The rule split_if is now part of the default
   923 simpset. This means that the simplifier will eliminate all occurrences
   924 of if-then-else in the conclusion of a goal. To prevent this, you can
   925 either remove split_if completely from the default simpset by
   926 `Delsplits [split_if]' or remove it in a specific call of the
   927 simplifier using `... delsplits [split_if]'.  You can also add/delete
   928 other case splitting rules to/from the default simpset: every datatype
   929 generates suitable rules `split_t_case' and `split_t_case_asm' (where
   930 t is the name of the datatype).
   931 
   932 * Classical reasoner / Simplifier combination: new force_tac (and
   933 derivatives Force_tac, force) combines rewriting and classical
   934 reasoning (and whatever other tools) similarly to auto_tac, but is
   935 aimed to solve the given subgoal completely.
   936 
   937 
   938 *** General ***
   939 
   940 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
   941 and `goalw': the theory is no longer needed as an explicit argument -
   942 the current theory context is used; assumptions are no longer returned
   943 at the ML-level unless one of them starts with ==> or !!; it is
   944 recommended to convert to these new commands using isatool fixgoal
   945 (backup your sources first!);
   946 
   947 * new top-level commands 'thm' and 'thms' for retrieving theorems from
   948 the current theory context, and 'theory' to lookup stored theories;
   949 
   950 * new theory section 'locale' for declaring constants, assumptions and
   951 definitions that have local scope;
   952 
   953 * new theory section 'nonterminals' for purely syntactic types;
   954 
   955 * new theory section 'setup' for generic ML setup functions
   956 (e.g. package initialization);
   957 
   958 * the distribution now includes Isabelle icons: see
   959 lib/logo/isabelle-{small,tiny}.xpm;
   960 
   961 * isatool install - install binaries with absolute references to
   962 ISABELLE_HOME/bin;
   963 
   964 * isatool logo -- create instances of the Isabelle logo (as EPS);
   965 
   966 * print mode 'emacs' reserved for Isamode;
   967 
   968 * support multiple print (ast) translations per constant name;
   969 
   970 * theorems involving oracles are now printed with a suffixed [!];
   971 
   972 
   973 *** HOL ***
   974 
   975 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
   976 
   977 * HOL/inductive package reorganized and improved: now supports mutual
   978 definitions such as
   979 
   980   inductive EVEN ODD
   981     intrs
   982       null "0 : EVEN"
   983       oddI "n : EVEN ==> Suc n : ODD"
   984       evenI "n : ODD ==> Suc n : EVEN"
   985 
   986 new theorem list "elims" contains an elimination rule for each of the
   987 recursive sets; inductive definitions now handle disjunctive premises
   988 correctly (also ZF);
   989 
   990 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   991 "mutual_induct" no longer exists - the induction rule is always
   992 contained in "induct";
   993 
   994 
   995 * HOL/datatype package re-implemented and greatly improved: now
   996 supports mutually recursive datatypes such as
   997 
   998   datatype
   999     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1000             | SUM ('a aexp) ('a aexp)
  1001             | DIFF ('a aexp) ('a aexp)
  1002             | NUM 'a
  1003   and
  1004     'a bexp = LESS ('a aexp) ('a aexp)
  1005             | AND ('a bexp) ('a bexp)
  1006             | OR ('a bexp) ('a bexp)
  1007 
  1008 as well as indirectly recursive datatypes such as
  1009 
  1010   datatype
  1011     ('a, 'b) term = Var 'a
  1012                   | App 'b ((('a, 'b) term) list)
  1013 
  1014 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1015 induction on mutually / indirectly recursive datatypes.
  1016 
  1017 Primrec equations are now stored in theory and can be accessed via
  1018 <function_name>.simps.
  1019 
  1020 INCOMPATIBILITIES:
  1021 
  1022   - Theories using datatypes must now have theory Datatype as an
  1023     ancestor.
  1024   - The specific <typename>.induct_tac no longer exists - use the
  1025     generic induct_tac instead.
  1026   - natE has been renamed to nat.exhaust - use exhaust_tac
  1027     instead of res_inst_tac ... natE. Note that the variable
  1028     names in nat.exhaust differ from the names in natE, this
  1029     may cause some "fragile" proofs to fail.
  1030   - The theorems split_<typename>_case and split_<typename>_case_asm
  1031     have been renamed to <typename>.split and <typename>.split_asm.
  1032   - Since default sorts of type variables are now handled correctly,
  1033     some datatype definitions may have to be annotated with explicit
  1034     sort constraints.
  1035   - Primrec definitions no longer require function name and type
  1036     of recursive argument.
  1037 
  1038 Consider using isatool fixdatatype to adapt your theories and proof
  1039 scripts to the new package (backup your sources first!).
  1040 
  1041 
  1042 * HOL/record package: considerably improved implementation; now
  1043 includes concrete syntax for record types, terms, updates; theorems
  1044 for surjective pairing and splitting !!-bound record variables; proof
  1045 support is as follows:
  1046 
  1047   1) standard conversions (selectors or updates applied to record
  1048 constructor terms) are part of the standard simpset;
  1049 
  1050   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1051 made part of standard simpset and claset via addIffs;
  1052 
  1053   3) a tactic for record field splitting (record_split_tac) is part of
  1054 the standard claset (addSWrapper);
  1055 
  1056 To get a better idea about these rules you may retrieve them via
  1057 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1058 the name of your record type.
  1059 
  1060 The split tactic 3) conceptually simplifies by the following rule:
  1061 
  1062   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1063 
  1064 Thus any record variable that is bound by meta-all will automatically
  1065 blow up into some record constructor term, consequently the
  1066 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1067 solve record problems automatically.
  1068 
  1069 
  1070 * reorganized the main HOL image: HOL/Integ and String loaded by
  1071 default; theory Main includes everything;
  1072 
  1073 * automatic simplification of integer sums and comparisons, using cancellation;
  1074 
  1075 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1076 
  1077 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1078 
  1079 * many new identities for unions, intersections, set difference, etc.;
  1080 
  1081 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1082 called split_if, split_split, split_sum_case and split_nat_case (to go
  1083 with add/delsplits);
  1084 
  1085 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1086 (?x::unit) = (); this is made part of the default simpset, which COULD
  1087 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1088 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1089 unit_abs_eta_conv is added in order to counter the effect of
  1090 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1091 %u.f();
  1092 
  1093 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1094 makes more sense);
  1095 
  1096 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1097   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1098   disjointness reasoning but breaking a few old proofs.
  1099 
  1100 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1101 to 'converse' from 'inverse' (for compatibility with ZF and some
  1102 literature);
  1103 
  1104 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1105 the well-founded relation;
  1106 
  1107 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1108     Compl A.  The "Compl" syntax remains available as input syntax for this
  1109     release ONLY.
  1110 
  1111 * HOL/Update: new theory of function updates:
  1112     f(a:=b) == %x. if x=a then b else f x
  1113 may also be iterated as in f(a:=b,c:=d,...);
  1114 
  1115 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1116 
  1117 * HOL/List:
  1118   - new function list_update written xs[i:=v] that updates the i-th
  1119     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1120   - new function `upt' written [i..j(] which generates the list
  1121     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1122     bound write [i..j], which is a shorthand for [i..j+1(].
  1123   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1124 
  1125 * HOL/Arith:
  1126   - removed 'pred' (predecessor) function;
  1127   - generalized some theorems about n-1;
  1128   - many new laws about "div" and "mod";
  1129   - new laws about greatest common divisors (see theory ex/Primes);
  1130 
  1131 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1132 instead of "inverse";
  1133 
  1134 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1135   of the multiset ordering;
  1136 
  1137 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1138   (not included by default);
  1139 
  1140 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1141 
  1142 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1143   programs, i.e. different program variables may have different types.
  1144 
  1145 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1146   [previously, this check worked only if the rewrite rule was unconditional]
  1147   Now rew can involve either definitions or equalities (either == or =).
  1148 
  1149 
  1150 *** ZF ***
  1151 
  1152 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1153   only the theorems proved on ZF.ML;
  1154 
  1155 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1156   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1157   disjointness reasoning but breaking a few old proofs.
  1158 
  1159 * ZF/Update: new theory of function updates
  1160     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1161   may also be iterated as in f(a:=b,c:=d,...);
  1162 
  1163 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1164 
  1165 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1166   [previously, this check worked only if the rewrite rule was unconditional]
  1167   Now rew can involve either definitions or equalities (either == or =).
  1168 
  1169 * case_tac provided for compatibility with HOL
  1170     (like the old excluded_middle_tac, but with subgoals swapped)
  1171 
  1172 
  1173 *** Internal programming interfaces ***
  1174 
  1175 * Pure: several new basic modules made available for general use, see
  1176 also src/Pure/README;
  1177 
  1178 * improved the theory data mechanism to support encapsulation (data
  1179 kind name replaced by private Object.kind, acting as authorization
  1180 key); new type-safe user interface via functor TheoryDataFun; generic
  1181 print_data function becomes basically useless;
  1182 
  1183 * removed global_names compatibility flag -- all theory declarations
  1184 are qualified by default;
  1185 
  1186 * module Pure/Syntax now offers quote / antiquote translation
  1187 functions (useful for Hoare logic etc. with implicit dependencies);
  1188 see HOL/ex/Antiquote for an example use;
  1189 
  1190 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1191 cterm -> thm;
  1192 
  1193 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1194 subgoal;
  1195 
  1196 * Display.print_goals function moved to Locale.print_goals;
  1197 
  1198 * standard print function for goals supports current_goals_markers
  1199 variable for marking begin of proof, end of proof, start of goal; the
  1200 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1201 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1202 for example;
  1203 
  1204 
  1205 
  1206 New in Isabelle98 (January 1998)
  1207 --------------------------------
  1208 
  1209 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1210 
  1211 * changed lexical syntax of terms / types: dots made part of long
  1212 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1213 
  1214 * simpset (and claset) reference variable replaced by functions
  1215 simpset / simpset_ref;
  1216 
  1217 * no longer supports theory aliases (via merge) and non-trivial
  1218 implicit merge of thms' signatures;
  1219 
  1220 * most internal names of constants changed due to qualified names;
  1221 
  1222 * changed Pure/Sequence interface (see Pure/seq.ML);
  1223 
  1224 
  1225 *** General Changes ***
  1226 
  1227 * hierachically structured name spaces (for consts, types, axms, thms
  1228 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1229 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1230 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1231 long_names for fully qualified output names; NOTE: ML programs
  1232 (special tactics, packages etc.) referring to internal names may have
  1233 to be adapted to cope with fully qualified names; in case of severe
  1234 backward campatibility problems try setting 'global_names' at compile
  1235 time to have enrything declared within a flat name space; one may also
  1236 fine tune name declarations in theories via the 'global' and 'local'
  1237 section;
  1238 
  1239 * reimplemented the implicit simpset and claset using the new anytype
  1240 data filed in signatures; references simpset:simpset ref etc. are
  1241 replaced by functions simpset:unit->simpset and
  1242 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1243 to patch your ML files accordingly;
  1244 
  1245 * HTML output now includes theory graph data for display with Java
  1246 applet or isatool browser; data generated automatically via isatool
  1247 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1248 
  1249 * defs may now be conditional; improved rewrite_goals_tac to handle
  1250 conditional equations;
  1251 
  1252 * defs now admits additional type arguments, using TYPE('a) syntax;
  1253 
  1254 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1255 creates a new theory node; implicit merge of thms' signatures is
  1256 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1257 transfer:theory->thm->thm in (rare) cases;
  1258 
  1259 * improved handling of draft signatures / theories; draft thms (and
  1260 ctyps, cterms) are automatically promoted to real ones;
  1261 
  1262 * slightly changed interfaces for oracles: admit many per theory, named
  1263 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1264 
  1265 * print_goals: optional output of const types (set show_consts and
  1266 show_types);
  1267 
  1268 * improved output of warnings (###) and errors (***);
  1269 
  1270 * subgoal_tac displays a warning if the new subgoal has type variables;
  1271 
  1272 * removed old README and Makefiles;
  1273 
  1274 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1275 
  1276 * removed obsolete init_pps and init_database;
  1277 
  1278 * deleted the obsolete tactical STATE, which was declared by
  1279     fun STATE tacfun st = tacfun st st;
  1280 
  1281 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1282 (which abbreviates $HOME);
  1283 
  1284 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1285 use isatool fixseq to adapt your ML programs (this works for fully
  1286 qualified references to the Sequence structure only!);
  1287 
  1288 * use_thy no longer requires writable current directory; it always
  1289 reloads .ML *and* .thy file, if either one is out of date;
  1290 
  1291 
  1292 *** Classical Reasoner ***
  1293 
  1294 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1295 tactics that use classical reasoning to simplify a subgoal without
  1296 splitting it into several subgoals;
  1297 
  1298 * Safe_tac: like safe_tac but uses the default claset;
  1299 
  1300 
  1301 *** Simplifier ***
  1302 
  1303 * added simplification meta rules:
  1304     (asm_)(full_)simplify: simpset -> thm -> thm;
  1305 
  1306 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1307 logics (again);
  1308 
  1309 * added prems argument to simplification procedures;
  1310 
  1311 * HOL, FOL, ZF: added infix function `addsplits':
  1312   instead of `<simpset> setloop (split_tac <thms>)'
  1313   you can simply write `<simpset> addsplits <thms>'
  1314 
  1315 
  1316 *** Syntax ***
  1317 
  1318 * TYPE('a) syntax for type reflection terms;
  1319 
  1320 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1321 
  1322 * pretty printer: changed order of mixfix annotation preference (again!);
  1323 
  1324 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1325 
  1326 
  1327 *** HOL ***
  1328 
  1329 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1330   with `addloop' of the simplifier to faciliate case splitting in premises.
  1331 
  1332 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1333 
  1334 * HOL/Auth: new protocol proofs including some for the Internet
  1335   protocol TLS;
  1336 
  1337 * HOL/Map: new theory of `maps' a la VDM;
  1338 
  1339 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1340 cancelling out common nat summands from =, <, <= (in)equalities, or
  1341 differences; simplification procedures nat_cancel_factor for
  1342 cancelling common factor from =, <, <= (in)equalities over natural
  1343 sums; nat_cancel contains both kinds of procedures, it is installed by
  1344 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1345 
  1346 * HOL/simplifier: terms of the form
  1347   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1348   are rewritten to
  1349   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1350   and those of the form
  1351   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1352   are rewritten to
  1353   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1354 
  1355 * HOL/datatype
  1356   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1357 
  1358   P(t_case f1 ... fn x) =
  1359      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1360         ...
  1361        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1362      )
  1363 
  1364   and a theorem `split_t_case_asm' of the form
  1365 
  1366   P(t_case f1 ... fn x) =
  1367     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1368         ...
  1369        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1370      )
  1371   which can be added to a simpset via `addsplits'. The existing theorems
  1372   expand_list_case and expand_option_case have been renamed to
  1373   split_list_case and split_option_case.
  1374 
  1375 * HOL/Arithmetic:
  1376   - `pred n' is automatically converted to `n-1'.
  1377     Users are strongly encouraged not to use `pred' any longer,
  1378     because it will disappear altogether at some point.
  1379   - Users are strongly encouraged to write "0 < n" rather than
  1380     "n ~= 0". Theorems and proof tools have been modified towards this
  1381     `standard'.
  1382 
  1383 * HOL/Lists:
  1384   the function "set_of_list" has been renamed "set" (and its theorems too);
  1385   the function "nth" now takes its arguments in the reverse order and
  1386   has acquired the infix notation "!" as in "xs!n".
  1387 
  1388 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1389 
  1390 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1391   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1392 
  1393 * HOL/record: extensible records with schematic structural subtyping
  1394 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1395 still lacks various theorems and concrete record syntax;
  1396 
  1397 
  1398 *** HOLCF ***
  1399 
  1400 * removed "axioms" and "generated by" sections;
  1401 
  1402 * replaced "ops" section by extended "consts" section, which is capable of
  1403   handling the continuous function space "->" directly;
  1404 
  1405 * domain package:
  1406   . proves theorems immediately and stores them in the theory,
  1407   . creates hierachical name space,
  1408   . now uses normal mixfix annotations (instead of cinfix...),
  1409   . minor changes to some names and values (for consistency),
  1410   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1411   . separator between mutual domain defs: changed "," to "and",
  1412   . improved handling of sort constraints;  now they have to
  1413     appear on the left-hand side of the equations only;
  1414 
  1415 * fixed LAM <x,y,zs>.b syntax;
  1416 
  1417 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1418 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1419 
  1420 
  1421 *** FOL and ZF ***
  1422 
  1423 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1424   with `addloop' of the simplifier to faciliate case splitting in premises.
  1425 
  1426 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1427 in HOL, they strip ALL and --> from proved theorems;
  1428 
  1429 
  1430 
  1431 New in Isabelle94-8 (May 1997)
  1432 ------------------------------
  1433 
  1434 *** General Changes ***
  1435 
  1436 * new utilities to build / run / maintain Isabelle etc. (in parts
  1437 still somewhat experimental); old Makefiles etc. still functional;
  1438 
  1439 * new 'Isabelle System Manual';
  1440 
  1441 * INSTALL text, together with ./configure and ./build scripts;
  1442 
  1443 * reimplemented type inference for greater efficiency, better error
  1444 messages and clean internal interface;
  1445 
  1446 * prlim command for dealing with lots of subgoals (an easier way of
  1447 setting goals_limit);
  1448 
  1449 
  1450 *** Syntax ***
  1451 
  1452 * supports alternative (named) syntax tables (parser and pretty
  1453 printer); internal interface is provided by add_modesyntax(_i);
  1454 
  1455 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1456 be used in conjunction with the Isabelle symbol font; uses the
  1457 "symbols" syntax table;
  1458 
  1459 * added token_translation interface (may translate name tokens in
  1460 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1461 the current print_mode); IMPORTANT: user print translation functions
  1462 are responsible for marking newly introduced bounds
  1463 (Syntax.mark_boundT);
  1464 
  1465 * token translations for modes "xterm" and "xterm_color" that display
  1466 names in bold, underline etc. or colors (which requires a color
  1467 version of xterm);
  1468 
  1469 * infixes may now be declared with names independent of their syntax;
  1470 
  1471 * added typed_print_translation (like print_translation, but may
  1472 access type of constant);
  1473 
  1474 
  1475 *** Classical Reasoner ***
  1476 
  1477 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  1478 some limitations.  Blast_tac...
  1479   + ignores addss, addbefore, addafter; this restriction is intrinsic
  1480   + ignores elimination rules that don't have the correct format
  1481         (the conclusion MUST be a formula variable)
  1482   + ignores types, which can make HOL proofs fail
  1483   + rules must not require higher-order unification, e.g. apply_type in ZF
  1484     [message "Function Var's argument not a bound variable" relates to this]
  1485   + its proof strategy is more general but can actually be slower
  1486 
  1487 * substitution with equality assumptions no longer permutes other
  1488 assumptions;
  1489 
  1490 * minor changes in semantics of addafter (now called addaltern); renamed
  1491 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  1492 (and access functions for it);
  1493 
  1494 * improved combination of classical reasoner and simplifier:
  1495   + functions for handling clasimpsets
  1496   + improvement of addss: now the simplifier is called _after_ the
  1497     safe steps.
  1498   + safe variant of addss called addSss: uses safe simplifications
  1499     _during_ the safe steps. It is more complete as it allows multiple
  1500     instantiations of unknowns (e.g. with slow_tac).
  1501 
  1502 *** Simplifier ***
  1503 
  1504 * added interface for simplification procedures (functions that
  1505 produce *proven* rewrite rules on the fly, depending on current
  1506 redex);
  1507 
  1508 * ordering on terms as parameter (used for ordered rewriting);
  1509 
  1510 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  1511 
  1512 * the solver is now split into a safe and an unsafe part.
  1513 This should be invisible for the normal user, except that the
  1514 functions setsolver and addsolver have been renamed to setSolver and
  1515 addSolver; added safe_asm_full_simp_tac;
  1516 
  1517 
  1518 *** HOL ***
  1519 
  1520 * a generic induction tactic `induct_tac' which works for all datatypes and
  1521 also for type `nat';
  1522 
  1523 * a generic case distinction tactic `exhaust_tac' which works for all
  1524 datatypes and also for type `nat';
  1525 
  1526 * each datatype comes with a function `size';
  1527 
  1528 * patterns in case expressions allow tuple patterns as arguments to
  1529 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1530 
  1531 * primrec now also works with type nat;
  1532 
  1533 * recdef: a new declaration form, allows general recursive functions to be
  1534 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1535 
  1536 * the constant for negation has been renamed from "not" to "Not" to
  1537 harmonize with FOL, ZF, LK, etc.;
  1538 
  1539 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1540 infinite lists;
  1541 
  1542 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1543 
  1544 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1545 problems in commutative rings, using axiomatic type classes for + and *;
  1546 
  1547 * more examples in HOL/MiniML and HOL/Auth;
  1548 
  1549 * more default rewrite rules for quantifiers, union/intersection;
  1550 
  1551 * a new constant `arbitrary == @x.False';
  1552 
  1553 * HOLCF/IOA replaces old HOL/IOA;
  1554 
  1555 * HOLCF changes: derived all rules and arities
  1556   + axiomatic type classes instead of classes
  1557   + typedef instead of faking type definitions
  1558   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1559   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1560   + eliminated the types void, one, tr
  1561   + use unit lift and bool lift (with translations) instead of one and tr
  1562   + eliminated blift from Lift3.thy (use Def instead of blift)
  1563   all eliminated rules are derived as theorems --> no visible changes ;
  1564 
  1565 
  1566 *** ZF ***
  1567 
  1568 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1569 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1570 as ZF_cs addSIs [equalityI];
  1571 
  1572 
  1573 
  1574 New in Isabelle94-7 (November 96)
  1575 ---------------------------------
  1576 
  1577 * allowing negative levels (as offsets) in prlev and choplev;
  1578 
  1579 * super-linear speedup for large simplifications;
  1580 
  1581 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1582 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1583 FAIL); can suppress it using the command Delsimps (ex_simps @
  1584 all_simps); De Morgan laws are also now included, by default;
  1585 
  1586 * improved printing of ==>  :  ~:
  1587 
  1588 * new object-logic "Sequents" adds linear logic, while replacing LK
  1589 and Modal (thanks to Sara Kalvala);
  1590 
  1591 * HOL/Auth: correctness proofs for authentication protocols;
  1592 
  1593 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1594 examples on HOL/Auth);
  1595 
  1596 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1597 the rewriter and classical reasoner simultaneously;
  1598 
  1599 * function uresult no longer returns theorems in "standard" format;
  1600 regain previous version by: val uresult = standard o uresult;
  1601 
  1602 
  1603 
  1604 New in Isabelle94-6
  1605 -------------------
  1606 
  1607 * oracles -- these establish an interface between Isabelle and trusted
  1608 external reasoners, which may deliver results as theorems;
  1609 
  1610 * proof objects (in particular record all uses of oracles);
  1611 
  1612 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1613 
  1614 * "constdefs" section in theory files;
  1615 
  1616 * "primrec" section (HOL) no longer requires names;
  1617 
  1618 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1619 
  1620 
  1621 
  1622 New in Isabelle94-5
  1623 -------------------
  1624 
  1625 * reduced space requirements;
  1626 
  1627 * automatic HTML generation from theories;
  1628 
  1629 * theory files no longer require "..." (quotes) around most types;
  1630 
  1631 * new examples, including two proofs of the Church-Rosser theorem;
  1632 
  1633 * non-curried (1994) version of HOL is no longer distributed;
  1634 
  1635 
  1636 
  1637 New in Isabelle94-4
  1638 -------------------
  1639 
  1640 * greatly reduced space requirements;
  1641 
  1642 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1643 
  1644 * searchable theorem database (see the section "Retrieving theorems" on
  1645 page 8 of the Reference Manual);
  1646 
  1647 * new examples, including Grabczewski's monumental case study of the
  1648 Axiom of Choice;
  1649 
  1650 * The previous version of HOL renamed to Old_HOL;
  1651 
  1652 * The new version of HOL (previously called CHOL) uses a curried syntax
  1653 for functions.  Application looks like f a b instead of f(a,b);
  1654 
  1655 * Mutually recursive inductive definitions finally work in HOL;
  1656 
  1657 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1658 translates to the operator "split";
  1659 
  1660 
  1661 
  1662 New in Isabelle94-3
  1663 -------------------
  1664 
  1665 * new infix operator, addss, allowing the classical reasoner to
  1666 perform simplification at each step of its search.  Example:
  1667         fast_tac (cs addss ss)
  1668 
  1669 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1670 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1671 look like (a,b) instead of <a,b>;
  1672 
  1673 * PLEASE NOTE: CHOL will eventually replace HOL!
  1674 
  1675 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1676 It translates to the operator "split".  A new theory of integers is available;
  1677 
  1678 * In ZF, integer numerals now denote two's-complement binary integers.
  1679 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1680 
  1681 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1682 of the Axiom of Choice;
  1683 
  1684 
  1685 
  1686 New in Isabelle94-2
  1687 -------------------
  1688 
  1689 * Significantly faster resolution;
  1690 
  1691 * the different sections in a .thy file can now be mixed and repeated
  1692 freely;
  1693 
  1694 * Database of theorems for FOL, HOL and ZF.  New
  1695 commands including qed, qed_goal and bind_thm store theorems in the database.
  1696 
  1697 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1698 a given theory (thms_of), or find out what theory a theorem was proved in
  1699 (theory_of_thm);
  1700 
  1701 * Bugs fixed in the inductive definition and datatype packages;
  1702 
  1703 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1704 and HOL_dup_cs obsolete;
  1705 
  1706 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1707 have been removed;
  1708 
  1709 * Simpler definition of function space in ZF;
  1710 
  1711 * new results about cardinal and ordinal arithmetic in ZF;
  1712 
  1713 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1714 types;
  1715 
  1716 
  1717 $Id$