NEWS
author nipkow
Fri Jan 05 18:31:48 2001 +0100 (2001-01-05)
changeset 10793 4d6cf7702e3c
parent 10770 4858ad0b8f38
child 10799 ea69ee7e117b
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 
    16 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
    17 
    18 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
    19 consequence, it is no longer monotonic wrt. the local goal context
    20 (which is now passed through the inductive cases);
    21 
    22 
    23 *** Document preparation ***
    24 
    25 * improved isabelle style files; more abstract symbol implementation
    26 (should now use \isamath{...} and \isatext{...} in custom symbol
    27 definitions);
    28 
    29 * support sub/super scripts (for single symbols only), input syntax is
    30 like this: "A\<^sup>*" or "A\<^sup>\<star>";
    31 
    32 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
    33 state; Note that presentation of goal states does not conform to
    34 actual human-readable proof documents.  Please do not include goal
    35 states into document output unless you really know what you are doing!
    36 
    37 
    38 *** Isar ***
    39 
    40 * Pure: Isar now suffers initial goal statements to contain unbound
    41 schematic variables (this does not conform to actual readable proof
    42 documents, due to unpredictable outcome and non-compositional proof
    43 checking); users who know what they are doing may use schematic goals
    44 for Prolog-style synthesis of proven results;
    45 
    46 * Pure: assumption method (an implicit finishing) now handles actual
    47 rules as well;
    48 
    49 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
    50 initial goal, declare "that" only as Pure intro (only for single
    51 steps); the "that" rule assumption may now be involved in implicit
    52 finishing, thus ".." becomes a feasible for trivial obtains;
    53 
    54 * Pure: default proof step now includes 'intro_classes'; thus trivial
    55 instance proofs may be performed by "..";
    56 
    57 * Pure: ?thesis / ?this / "..." now work for pure meta-level
    58 statements as well;
    59 
    60 * HOL: improved method 'induct' --- now handles non-atomic goals
    61 (potential INCOMPATIBILITY); tuned error handling;
    62 
    63 * HOL: cases and induct rules now provide explicit hints about the
    64 number of facts to be consumed (0 for "type" and 1 for "set" rules);
    65 any remaining facts are inserted into the goal verbatim;
    66 
    67 * HOL: added 'recdef_tc' command;
    68 
    69 
    70 *** HOL ***
    71 
    72 * HOL/Library: a collection of generic theories to be used together
    73 with main HOL; the theory loader path already includes this directory
    74 by default; the following existing theories have been moved here:
    75 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
    76 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
    77 
    78 * HOL basics: added overloaded operations "inverse" and "divide"
    79 (infix "/"), syntax for generic "abs" operation, generic summation
    80 operator;
    81 
    82 * HOL/typedef: simplified package, provide more useful rules (see also
    83 HOL/subset.thy);
    84 
    85 * HOL-Hyperreal: a new target, extending HOL-Real with the hyperreals and 
    86 Fleuriot's mechanization of analysis;
    87 
    88 * HOL-Real, HOL-Hyperreals: improved arithmetic simplification;
    89 
    90 *** CTT ***
    91 
    92 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
    93 "lam" is displayed as TWO lambda-symbols
    94 
    95 * CTT: theory Main now available, containing everything (that is, Bool
    96 and Arith);
    97 
    98 
    99 *** General ***
   100 
   101 * print modes "brackets" and "no_brackets" control output of nested =>
   102 (types) and ==> (props); the default behaviour is "brackets";
   103 
   104 * system: support Poly/ML 4.0 (current beta versions);
   105 
   106 * Pure: the Simplifier has been implemented properly as a derived rule
   107 outside of the actual kernel (at last!); the overall performance
   108 penalty in practical applications is about 50%, while reliability of
   109 the Isabelle inference kernel has been greatly improved;
   110 
   111 * Provers: fast_tac (and friends) now handle actual object-logic rules
   112 as assumptions as well;
   113 
   114 
   115 
   116 New in Isabelle99-1 (October 2000)
   117 ----------------------------------
   118 
   119 *** Overview of INCOMPATIBILITIES ***
   120 
   121 * HOL: simplification of natural numbers is much changed; to partly
   122 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   123 issue the following ML commands:
   124 
   125   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   126   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   127 
   128 * HOL: simplification no longer dives into case-expressions; this is
   129 controlled by "t.weak_case_cong" for each datatype t;
   130 
   131 * HOL: nat_less_induct renamed to less_induct;
   132 
   133 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   134 fixsome to patch .thy and .ML sources automatically;
   135 
   136   select_equality  -> some_equality
   137   select_eq_Ex     -> some_eq_ex
   138   selectI2EX       -> someI2_ex
   139   selectI2         -> someI2
   140   selectI          -> someI
   141   select1_equality -> some1_equality
   142   Eps_sym_eq       -> some_sym_eq_trivial
   143   Eps_eq           -> some_eq_trivial
   144 
   145 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   146 
   147 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   148 instead);
   149 
   150 * HOL: the recursion equations generated by 'recdef' are now called
   151 f.simps instead of f.rules;
   152 
   153 * HOL: qed_spec_mp now also handles bounded ALL as well;
   154 
   155 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   156 sometimes be needed;
   157 
   158 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   159 
   160 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   161 
   162 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   163 product is now "<*>" instead of "Times"; the lexicographic product is
   164 now "<*lex*>" instead of "**";
   165 
   166 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   167 of main HOL, but was unused); better use HOL's datatype package;
   168 
   169 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   170 the old syntax may be recovered as follows:
   171 
   172   syntax (symbols)
   173     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   174       (infixl "\\<oplus>" 100)
   175 
   176 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   177 
   178 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   179 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   180 internally;
   181 
   182 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   183 changed from A/r to A//r;
   184 
   185 * ZF: new treatment of arithmetic (nat & int) may break some old
   186 proofs;
   187 
   188 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   189 rulify -> rule_format, elimify -> elim_format, ...);
   190 
   191 * Isar/Provers: intro/elim/dest attributes changed; renamed
   192 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   193 should have to change intro!! to intro? only); replaced "delrule" by
   194 "rule del";
   195 
   196 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   197 
   198 * Provers: strengthened force_tac by using new first_best_tac;
   199 
   200 * LaTeX document preparation: several changes of isabelle.sty (see
   201 lib/texinputs);
   202 
   203 
   204 *** Document preparation ***
   205 
   206 * formal comments (text blocks etc.) in new-style theories may now
   207 contain antiquotations of thm/prop/term/typ/text to be presented
   208 according to latex print mode; concrete syntax is like this:
   209 @{term[show_types] "f(x) = a + x"};
   210 
   211 * isatool mkdir provides easy setup of Isabelle session directories,
   212 including proper document sources;
   213 
   214 * generated LaTeX sources are now deleted after successful run
   215 (isatool document -c); may retain a copy somewhere else via -D option
   216 of isatool usedir;
   217 
   218 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   219 style files, achieving self-contained LaTeX sources and simplifying
   220 LaTeX debugging;
   221 
   222 * old-style theories now produce (crude) LaTeX output as well;
   223 
   224 * browser info session directories are now self-contained (may be put
   225 on WWW server seperately); improved graphs of nested sessions; removed
   226 graph for 'all sessions';
   227 
   228 * several improvements in isabelle style files; \isabellestyle{it}
   229 produces fake math mode output; \isamarkupheader is now \section by
   230 default; see lib/texinputs/isabelle.sty etc.;
   231 
   232 
   233 *** Isar ***
   234 
   235 * Isar/Pure: local results and corresponding term bindings are now
   236 subject to Hindley-Milner polymorphism (similar to ML); this
   237 accommodates incremental type-inference very nicely;
   238 
   239 * Isar/Pure: new derived language element 'obtain' supports
   240 generalized existence reasoning;
   241 
   242 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   243 support accumulation of results, without applying any rules yet;
   244 useful to collect intermediate results without explicit name
   245 references, and for use with transitivity rules with more than 2
   246 premises;
   247 
   248 * Isar/Pure: scalable support for case-analysis type proofs: new
   249 'case' language element refers to local contexts symbolically, as
   250 produced by certain proof methods; internally, case names are attached
   251 to theorems as "tags";
   252 
   253 * Isar/Pure: theory command 'hide' removes declarations from
   254 class/type/const name spaces;
   255 
   256 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   257 indicate potential overloading;
   258 
   259 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   260 
   261 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   262 "{a,b,c}" instead of {a,b,c};
   263 
   264 * Isar/Pure now provides its own version of intro/elim/dest
   265 attributes; useful for building new logics, but beware of confusion
   266 with the version in Provers/classical;
   267 
   268 * Isar/Pure: the local context of (non-atomic) goals is provided via
   269 case name 'antecedent';
   270 
   271 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   272 to the current context is now done automatically);
   273 
   274 * Isar/Pure: theory command 'method_setup' provides a simple interface
   275 for definining proof methods in ML;
   276 
   277 * Isar/Provers: intro/elim/dest attributes changed; renamed
   278 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   279 most cases, one should have to change intro!! to intro? only);
   280 replaced "delrule" by "rule del";
   281 
   282 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   283 'symmetric' attribute (the latter supercedes [RS sym]);
   284 
   285 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   286 method modifier); 'simp' method: 'only:' modifier removes loopers as
   287 well (including splits);
   288 
   289 * Isar/Provers: Simplifier and Classical methods now support all kind
   290 of modifiers used in the past, including 'cong', 'iff', etc.
   291 
   292 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   293 of Simplifier and Classical reasoner);
   294 
   295 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   296 now support named cases; major packages (inductive, datatype, primrec,
   297 recdef) support case names and properly name parameters;
   298 
   299 * Isar/HOL: new transitivity rules for substitution in inequalities --
   300 monotonicity conditions are extracted to be proven at end of
   301 calculations;
   302 
   303 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   304 method anyway;
   305 
   306 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   307 split_if split_if_asm; datatype package provides theorems foo.splits =
   308 foo.split foo.split_asm for each datatype;
   309 
   310 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   311 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   312 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   313 use "(cases (simplified))" method in proper proof texts);
   314 
   315 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   316 
   317 * Isar: names of theorems etc. may be natural numbers as well;
   318 
   319 * Isar: 'pr' command: optional arguments for goals_limit and
   320 ProofContext.prems_limit; no longer prints theory contexts, but only
   321 proof states;
   322 
   323 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   324 additional print modes to be specified; e.g. "pr(latex)" will print
   325 proof state according to the Isabelle LaTeX style;
   326 
   327 * Isar: improved support for emulating tactic scripts, including proof
   328 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   329 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   330 (for HOL datatypes);
   331 
   332 * Isar: simplified (more robust) goal selection of proof methods: 1st
   333 goal, all goals, or explicit goal specifier (tactic emulation); thus
   334 'proof method scripts' have to be in depth-first order;
   335 
   336 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   337 
   338 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   339 should instead use individual commands for printing items
   340 (print_commands, print_methods etc.);
   341 
   342 * Isar: added 'nothing' --- the empty list of theorems;
   343 
   344 
   345 *** HOL ***
   346 
   347 * HOL/MicroJava: formalization of a fragment of Java, together with a
   348 corresponding virtual machine and a specification of its bytecode
   349 verifier and a lightweight bytecode verifier, including proofs of
   350 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   351 Cornelia Pusch (see also the homepage of project Bali at
   352 http://isabelle.in.tum.de/Bali/);
   353 
   354 * HOL/Algebra: new theory of rings and univariate polynomials, by
   355 Clemens Ballarin;
   356 
   357 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   358 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   359 Rasmussen;
   360 
   361 * HOL/Lattice: fundamental concepts of lattice theory and order
   362 structures, including duals, properties of bounds versus algebraic
   363 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   364 Theorem for complete lattices etc.; may also serve as a demonstration
   365 for abstract algebraic reasoning using axiomatic type classes, and
   366 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   367 
   368 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   369 von Oheimb;
   370 
   371 * HOL/IMPP: extension of IMP with local variables and mutually
   372 recursive procedures, by David von Oheimb;
   373 
   374 * HOL/Lambda: converted into new-style theory and document;
   375 
   376 * HOL/ex/Multiquote: example of multiple nested quotations and
   377 anti-quotations -- basically a generalized version of de-Bruijn
   378 representation; very useful in avoiding lifting of operations;
   379 
   380 * HOL/record: added general record equality rule to simpset; fixed
   381 select-update simplification procedure to handle extended records as
   382 well; admit "r" as field name;
   383 
   384 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   385 other numeric types and also as the identity of groups, rings, etc.;
   386 
   387 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   388 Types nat and int belong to this axclass;
   389 
   390 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   391    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   392    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   393   two terms #m*u and #n*u are replaced by #(m+n)*u
   394     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   395   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   396     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   397 
   398 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   399 powerful prover for predicate logic but knows nothing of clasets; see
   400 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   401 
   402 * HOL: new version of "case_tac" subsumes both boolean case split and
   403 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   404 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   405 
   406 * HOL: simplification no longer dives into case-expressions: only the
   407 selector expression is simplified, but not the remaining arms; to
   408 enable full simplification of case-expressions for datatype t, you may
   409 remove t.weak_case_cong from the simpset, either globally (Delcongs
   410 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   411 
   412 * HOL/recdef: the recursion equations generated by 'recdef' for
   413 function 'f' are now called f.simps instead of f.rules; if all
   414 termination conditions are proved automatically, these simplification
   415 rules are added to the simpset, as in primrec; rules may be named
   416 individually as well, resulting in a separate list of theorems for
   417 each equation;
   418 
   419 * HOL/While is a new theory that provides a while-combinator. It
   420 permits the definition of tail-recursive functions without the
   421 provision of a termination measure. The latter is necessary once the
   422 invariant proof rule for while is applied.
   423 
   424 * HOL: new (overloaded) notation for the set of elements below/above
   425 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   426 
   427 * HOL: theorems impI, allI, ballI bound as "strip";
   428 
   429 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   430 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   431 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   432 
   433 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   434 
   435 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   436 main HOL, but was unused);
   437 
   438 * HOL: fewer consts declared as global (e.g. have to refer to
   439 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   440 
   441 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   442 in case of overlap with user translations (e.g. judgements over
   443 tuples); (note that the underlying logical represenation is still
   444 bogus);
   445 
   446 
   447 *** ZF ***
   448 
   449 * ZF: simplification automatically cancels common terms in arithmetic
   450 expressions over nat and int;
   451 
   452 * ZF: new treatment of nat to minimize type-checking: all operators
   453 coerce their operands to a natural number using the function natify,
   454 making the algebraic laws unconditional;
   455 
   456 * ZF: as above, for int: operators coerce their operands to an integer
   457 using the function intify;
   458 
   459 * ZF: the integer library now contains many of the usual laws for the
   460 orderings, including $<=, and monotonicity laws for $+ and $*;
   461 
   462 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
   463 simplification;
   464 
   465 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
   466 to the simplifier and classical reasoner simultaneously;
   467 
   468 
   469 *** General ***
   470 
   471 * Provers: blast_tac now handles actual object-logic rules as
   472 assumptions; note that auto_tac uses blast_tac internally as well;
   473 
   474 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
   475 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
   476 
   477 * Provers: delrules now handles destruct rules as well (no longer need
   478 explicit make_elim);
   479 
   480 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
   481   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   482 use instead the strong form,
   483   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   484 in HOL, FOL and ZF the function cla_make_elim will create such rules
   485 from destruct-rules;
   486 
   487 * Provers: Simplifier.easy_setup provides a fast path to basic
   488 Simplifier setup for new object-logics;
   489 
   490 * Pure: AST translation rules no longer require constant head on LHS;
   491 
   492 * Pure: improved name spaces: ambiguous output is qualified; support
   493 for hiding of names;
   494 
   495 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
   496 XSYMBOL_HOME; no longer need to do manual configuration in most
   497 situations;
   498 
   499 * system: compression of ML heaps images may now be controlled via -c
   500 option of isabelle and isatool usedir (currently only observed by
   501 Poly/ML);
   502 
   503 * system: isatool installfonts may handle X-Symbol fonts as well (very
   504 useful for remote X11);
   505 
   506 * system: provide TAGS file for Isabelle sources;
   507 
   508 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
   509 order;
   510 
   511 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
   512 timing flag supersedes proof_timing and Toplevel.trace;
   513 
   514 * ML: new combinators |>> and |>>> for incremental transformations
   515 with secondary results (e.g. certain theory extensions):
   516 
   517 * ML: PureThy.add_defs gets additional argument to indicate potential
   518 overloading (usually false);
   519 
   520 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
   521 results;
   522 
   523 
   524 
   525 New in Isabelle99 (October 1999)
   526 --------------------------------
   527 
   528 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   529 
   530 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
   531 are no longer simplified.  (This allows the simplifier to unfold recursive
   532 functional programs.)  To restore the old behaviour, declare
   533 
   534     Delcongs [if_weak_cong];
   535 
   536 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
   537 complement;
   538 
   539 * HOL: the predicate "inj" is now defined by translation to "inj_on";
   540 
   541 * HOL/datatype: mutual_induct_tac no longer exists --
   542   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
   543 
   544 * HOL/typedef: fixed type inference for representing set; type
   545 arguments now have to occur explicitly on the rhs as type constraints;
   546 
   547 * ZF: The con_defs part of an inductive definition may no longer refer
   548 to constants declared in the same theory;
   549 
   550 * HOL, ZF: the function mk_cases, generated by the inductive
   551 definition package, has lost an argument.  To simplify its result, it
   552 uses the default simpset instead of a supplied list of theorems.
   553 
   554 * HOL/List: the constructors of type list are now Nil and Cons;
   555 
   556 * Simplifier: the type of the infix ML functions
   557         setSSolver addSSolver setSolver addSolver
   558 is now  simpset * solver -> simpset  where `solver' is a new abstract type
   559 for packaging solvers. A solver is created via
   560         mk_solver: string -> (thm list -> int -> tactic) -> solver
   561 where the string argument is only a comment.
   562 
   563 
   564 *** Proof tools ***
   565 
   566 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
   567 decision procedure for linear arithmetic. Currently it is used for
   568 types `nat', `int', and `real' in HOL (see below); it can, should and
   569 will be instantiated for other types and logics as well.
   570 
   571 * The simplifier now accepts rewrite rules with flexible heads, eg
   572      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
   573   They are applied like any rule with a non-pattern lhs, i.e. by first-order
   574   matching.
   575 
   576 
   577 *** General ***
   578 
   579 * New Isabelle/Isar subsystem provides an alternative to traditional
   580 tactical theorem proving; together with the ProofGeneral/isar user
   581 interface it offers an interactive environment for developing human
   582 readable proof documents (Isar == Intelligible semi-automated
   583 reasoning); for further information see isatool doc isar-ref,
   584 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
   585 
   586 * improved and simplified presentation of theories: better HTML markup
   587 (including colors), graph views in several sizes; isatool usedir now
   588 provides a proper interface for user theories (via -P option); actual
   589 document preparation based on (PDF)LaTeX is available as well (for
   590 new-style theories only); see isatool doc system for more information;
   591 
   592 * native support for Proof General, both for classic Isabelle and
   593 Isabelle/Isar;
   594 
   595 * ML function thm_deps visualizes dependencies of theorems and lemmas,
   596 using the graph browser tool;
   597 
   598 * Isabelle manuals now also available as PDF;
   599 
   600 * theory loader rewritten from scratch (may not be fully
   601 bug-compatible); old loadpath variable has been replaced by show_path,
   602 add_path, del_path, reset_path functions; new operations such as
   603 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
   604 isatool doc ref);
   605 
   606 * improved isatool install: option -k creates KDE application icon,
   607 option -p DIR installs standalone binaries;
   608 
   609 * added ML_PLATFORM setting (useful for cross-platform installations);
   610 more robust handling of platform specific ML images for SML/NJ;
   611 
   612 * the settings environment is now statically scoped, i.e. it is never
   613 created again in sub-processes invoked from isabelle, isatool, or
   614 Isabelle;
   615 
   616 * path element specification '~~' refers to '$ISABELLE_HOME';
   617 
   618 * in locales, the "assumes" and "defines" parts may be omitted if
   619 empty;
   620 
   621 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   622 long arrows);
   623 
   624 * new print_mode "HTML";
   625 
   626 * new flag show_tags controls display of tags of theorems (which are
   627 basically just comments that may be attached by some tools);
   628 
   629 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   630 mode and goal output format:
   631 
   632 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   633 244c244
   634 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   635 ---
   636 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   637 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   638 181c181
   639 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   640 ---
   641 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   642 
   643 * function bind_thms stores lists of theorems (cf. bind_thm);
   644 
   645 * new shorthand tactics ftac, eatac, datac, fatac;
   646 
   647 * qed (and friends) now accept "" as result name; in that case the
   648 theorem is not stored, but proper checks and presentation of the
   649 result still apply;
   650 
   651 * theorem database now also indexes constants "Trueprop", "all",
   652 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   653 
   654 
   655 *** HOL ***
   656 
   657 ** HOL arithmetic **
   658 
   659 * There are now decision procedures for linear arithmetic over nat and
   660 int:
   661 
   662 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   663 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   664 are treated as atomic; subformulae not involving type `nat' or `int'
   665 are ignored; quantified subformulae are ignored unless they are
   666 positive universal or negative existential. The tactic has to be
   667 invoked by hand and can be a little bit slow. In particular, the
   668 running time is exponential in the number of occurrences of `min' and
   669 `max', and `-' on `nat'.
   670 
   671 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   672 (negated) (in)equalities among the premises and the conclusion into
   673 account (i.e. no compound formulae) and does not know about `min' and
   674 `max', and `-' on `nat'. It is fast and is used automatically by the
   675 simplifier.
   676 
   677 NB: At the moment, these decision procedures do not cope with mixed
   678 nat/int formulae where the two parts interact, such as `m < n ==>
   679 int(m) < int(n)'.
   680 
   681 * HOL/Numeral provides a generic theory of numerals (encoded
   682 efficiently as bit strings); setup for types nat/int/real is in place;
   683 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   684 int, existing theories and proof scripts may require a few additional
   685 type constraints;
   686 
   687 * integer division and remainder can now be performed on constant
   688 arguments;
   689 
   690 * many properties of integer multiplication, division and remainder
   691 are now available;
   692 
   693 * An interface to the Stanford Validity Checker (SVC) is available through the
   694 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   695 are proved automatically.  SVC must be installed separately, and its results
   696 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   697 invocation of the underlying oracle).  For SVC see
   698   http://verify.stanford.edu/SVC
   699 
   700 * IsaMakefile: the HOL-Real target now builds an actual image;
   701 
   702 
   703 ** HOL misc **
   704 
   705 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   706 (in Isabelle/Isar) -- by Gertrud Bauer;
   707 
   708 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   709 analysis for assembly languages with subtypes;
   710 
   711 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   712 -- avoids syntactic ambiguities and treats state, transition, and
   713 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   714 changed syntax and (many) tactics;
   715 
   716 * HOL/inductive: Now also handles more general introduction rules such
   717   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
   718   theorems are now maintained within the theory (maintained via the
   719   "mono" attribute);
   720 
   721 * HOL/datatype: Now also handles arbitrarily branching datatypes
   722   (using function types) such as
   723 
   724   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
   725 
   726 * HOL/record: record_simproc (part of the default simpset) takes care
   727 of selectors applied to updated records; record_split_tac is no longer
   728 part of the default claset; update_defs may now be removed from the
   729 simpset in many cases; COMPATIBILITY: old behavior achieved by
   730 
   731   claset_ref () := claset() addSWrapper record_split_wrapper;
   732   Delsimprocs [record_simproc]
   733 
   734 * HOL/typedef: fixed type inference for representing set; type
   735 arguments now have to occur explicitly on the rhs as type constraints;
   736 
   737 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
   738 names rather than an ML expression;
   739 
   740 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
   741 supplied later.  Program schemes can be defined, such as
   742     "While B C s = (if B s then While B C (C s) else s)"
   743 where the well-founded relation can be chosen after B and C have been given.
   744 
   745 * HOL/List: the constructors of type list are now Nil and Cons;
   746 INCOMPATIBILITY: while [] and infix # syntax is still there, of
   747 course, ML tools referring to List.list.op # etc. have to be adapted;
   748 
   749 * HOL_quantifiers flag superseded by "HOL" print mode, which is
   750 disabled by default; run isabelle with option -m HOL to get back to
   751 the original Gordon/HOL-style output;
   752 
   753 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
   754 ALL x<=y. P, EX x<y. P, EX x<=y. P;
   755 
   756 * HOL basic syntax simplified (more orthogonal): all variants of
   757 All/Ex now support plain / symbolic / HOL notation; plain syntax for
   758 Eps operator is provided as well: "SOME x. P[x]";
   759 
   760 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
   761 
   762 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
   763 thus available for user theories;
   764 
   765 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
   766 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
   767 time;
   768 
   769 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
   770 several times and then mp;
   771 
   772 
   773 *** LK ***
   774 
   775 * the notation <<...>> is now available as a notation for sequences of
   776 formulas;
   777 
   778 * the simplifier is now installed
   779 
   780 * the axiom system has been generalized (thanks to Soren Heilmann)
   781 
   782 * the classical reasoner now has a default rule database
   783 
   784 
   785 *** ZF ***
   786 
   787 * new primrec section allows primitive recursive functions to be given
   788 directly (as in HOL) over datatypes and the natural numbers;
   789 
   790 * new tactics induct_tac and exhaust_tac for induction (or case
   791 analysis) over datatypes and the natural numbers;
   792 
   793 * the datatype declaration of type T now defines the recursor T_rec;
   794 
   795 * simplification automatically does freeness reasoning for datatype
   796 constructors;
   797 
   798 * automatic type-inference, with AddTCs command to insert new
   799 type-checking rules;
   800 
   801 * datatype introduction rules are now added as Safe Introduction rules
   802 to the claset;
   803 
   804 * the syntax "if P then x else y" is now available in addition to
   805 if(P,x,y);
   806 
   807 
   808 *** Internal programming interfaces ***
   809 
   810 * tuned simplifier trace output; new flag debug_simp;
   811 
   812 * structures Vartab / Termtab (instances of TableFun) offer efficient
   813 tables indexed by indexname_ord / term_ord (compatible with aconv);
   814 
   815 * AxClass.axclass_tac lost the theory argument;
   816 
   817 * tuned current_goals_markers semantics: begin / end goal avoids
   818 printing empty lines;
   819 
   820 * removed prs and prs_fn hook, which was broken because it did not
   821 include \n in its semantics, forcing writeln to add one
   822 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
   823 string -> unit if you really want to output text without newline;
   824 
   825 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
   826 plain output, interface builders may have to enable 'isabelle_font'
   827 mode to get Isabelle font glyphs as before;
   828 
   829 * refined token_translation interface; INCOMPATIBILITY: output length
   830 now of type real instead of int;
   831 
   832 * theory loader actions may be traced via new ThyInfo.add_hook
   833 interface (see src/Pure/Thy/thy_info.ML); example application: keep
   834 your own database of information attached to *whole* theories -- as
   835 opposed to intra-theory data slots offered via TheoryDataFun;
   836 
   837 * proper handling of dangling sort hypotheses (at last!);
   838 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
   839 extra sort hypotheses that can be witnessed from the type signature;
   840 the force_strip_shyps flag is gone, any remaining shyps are simply
   841 left in the theorem (with a warning issued by strip_shyps_warning);
   842 
   843 
   844 
   845 New in Isabelle98-1 (October 1998)
   846 ----------------------------------
   847 
   848 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   849 
   850 * several changes of automated proof tools;
   851 
   852 * HOL: major changes to the inductive and datatype packages, including
   853 some minor incompatibilities of theory syntax;
   854 
   855 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
   856 called `inj_on';
   857 
   858 * HOL: removed duplicate thms in Arith:
   859   less_imp_add_less  should be replaced by  trans_less_add1
   860   le_imp_add_le      should be replaced by  trans_le_add1
   861 
   862 * HOL: unary minus is now overloaded (new type constraints may be
   863 required);
   864 
   865 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
   866 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
   867 now taken as an integer constant.
   868 
   869 * Pure: ML function 'theory_of' renamed to 'theory';
   870 
   871 
   872 *** Proof tools ***
   873 
   874 * Simplifier:
   875   1. Asm_full_simp_tac is now more aggressive.
   876      1. It will sometimes reorient premises if that increases their power to
   877         simplify.
   878      2. It does no longer proceed strictly from left to right but may also
   879         rotate premises to achieve further simplification.
   880      For compatibility reasons there is now Asm_lr_simp_tac which is like the
   881      old Asm_full_simp_tac in that it does not rotate premises.
   882   2. The simplifier now knows a little bit about nat-arithmetic.
   883 
   884 * Classical reasoner: wrapper mechanism for the classical reasoner now
   885 allows for selected deletion of wrappers, by introduction of names for
   886 wrapper functionals.  This implies that addbefore, addSbefore,
   887 addaltern, and addSaltern now take a pair (name, tactic) as argument,
   888 and that adding two tactics with the same name overwrites the first
   889 one (emitting a warning).
   890   type wrapper = (int -> tactic) -> (int -> tactic)
   891   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
   892   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
   893   delWrapper, delSWrapper: claset *  string            -> claset
   894   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
   895 
   896 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
   897 semantics; addbefore now affects only the unsafe part of step_tac
   898 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
   899 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
   900 by Force_tac;
   901 
   902 * Classical reasoner: setwrapper to setWrapper and compwrapper to
   903 compWrapper; added safe wrapper (and access functions for it);
   904 
   905 * HOL/split_all_tac is now much faster and fails if there is nothing
   906 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
   907 and the names of the automatically generated variables have changed.
   908 split_all_tac has moved within claset() from unsafe wrappers to safe
   909 wrappers, which means that !!-bound variables are split much more
   910 aggressively, and safe_tac and clarify_tac now split such variables.
   911 If this splitting is not appropriate, use delSWrapper "split_all_tac".
   912 Note: the same holds for record_split_tac, which does the job of
   913 split_all_tac for record fields.
   914 
   915 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
   916 permanently to the default simpset using Addsplits just like
   917 Addsimps. They can be removed via Delsplits just like
   918 Delsimps. Lower-case versions are also available.
   919 
   920 * HOL/Simplifier: The rule split_if is now part of the default
   921 simpset. This means that the simplifier will eliminate all occurrences
   922 of if-then-else in the conclusion of a goal. To prevent this, you can
   923 either remove split_if completely from the default simpset by
   924 `Delsplits [split_if]' or remove it in a specific call of the
   925 simplifier using `... delsplits [split_if]'.  You can also add/delete
   926 other case splitting rules to/from the default simpset: every datatype
   927 generates suitable rules `split_t_case' and `split_t_case_asm' (where
   928 t is the name of the datatype).
   929 
   930 * Classical reasoner / Simplifier combination: new force_tac (and
   931 derivatives Force_tac, force) combines rewriting and classical
   932 reasoning (and whatever other tools) similarly to auto_tac, but is
   933 aimed to solve the given subgoal completely.
   934 
   935 
   936 *** General ***
   937 
   938 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
   939 and `goalw': the theory is no longer needed as an explicit argument -
   940 the current theory context is used; assumptions are no longer returned
   941 at the ML-level unless one of them starts with ==> or !!; it is
   942 recommended to convert to these new commands using isatool fixgoal
   943 (backup your sources first!);
   944 
   945 * new top-level commands 'thm' and 'thms' for retrieving theorems from
   946 the current theory context, and 'theory' to lookup stored theories;
   947 
   948 * new theory section 'locale' for declaring constants, assumptions and
   949 definitions that have local scope;
   950 
   951 * new theory section 'nonterminals' for purely syntactic types;
   952 
   953 * new theory section 'setup' for generic ML setup functions
   954 (e.g. package initialization);
   955 
   956 * the distribution now includes Isabelle icons: see
   957 lib/logo/isabelle-{small,tiny}.xpm;
   958 
   959 * isatool install - install binaries with absolute references to
   960 ISABELLE_HOME/bin;
   961 
   962 * isatool logo -- create instances of the Isabelle logo (as EPS);
   963 
   964 * print mode 'emacs' reserved for Isamode;
   965 
   966 * support multiple print (ast) translations per constant name;
   967 
   968 * theorems involving oracles are now printed with a suffixed [!];
   969 
   970 
   971 *** HOL ***
   972 
   973 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
   974 
   975 * HOL/inductive package reorganized and improved: now supports mutual
   976 definitions such as
   977 
   978   inductive EVEN ODD
   979     intrs
   980       null "0 : EVEN"
   981       oddI "n : EVEN ==> Suc n : ODD"
   982       evenI "n : ODD ==> Suc n : EVEN"
   983 
   984 new theorem list "elims" contains an elimination rule for each of the
   985 recursive sets; inductive definitions now handle disjunctive premises
   986 correctly (also ZF);
   987 
   988 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   989 "mutual_induct" no longer exists - the induction rule is always
   990 contained in "induct";
   991 
   992 
   993 * HOL/datatype package re-implemented and greatly improved: now
   994 supports mutually recursive datatypes such as
   995 
   996   datatype
   997     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
   998             | SUM ('a aexp) ('a aexp)
   999             | DIFF ('a aexp) ('a aexp)
  1000             | NUM 'a
  1001   and
  1002     'a bexp = LESS ('a aexp) ('a aexp)
  1003             | AND ('a bexp) ('a bexp)
  1004             | OR ('a bexp) ('a bexp)
  1005 
  1006 as well as indirectly recursive datatypes such as
  1007 
  1008   datatype
  1009     ('a, 'b) term = Var 'a
  1010                   | App 'b ((('a, 'b) term) list)
  1011 
  1012 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1013 induction on mutually / indirectly recursive datatypes.
  1014 
  1015 Primrec equations are now stored in theory and can be accessed via
  1016 <function_name>.simps.
  1017 
  1018 INCOMPATIBILITIES:
  1019 
  1020   - Theories using datatypes must now have theory Datatype as an
  1021     ancestor.
  1022   - The specific <typename>.induct_tac no longer exists - use the
  1023     generic induct_tac instead.
  1024   - natE has been renamed to nat.exhaust - use exhaust_tac
  1025     instead of res_inst_tac ... natE. Note that the variable
  1026     names in nat.exhaust differ from the names in natE, this
  1027     may cause some "fragile" proofs to fail.
  1028   - The theorems split_<typename>_case and split_<typename>_case_asm
  1029     have been renamed to <typename>.split and <typename>.split_asm.
  1030   - Since default sorts of type variables are now handled correctly,
  1031     some datatype definitions may have to be annotated with explicit
  1032     sort constraints.
  1033   - Primrec definitions no longer require function name and type
  1034     of recursive argument.
  1035 
  1036 Consider using isatool fixdatatype to adapt your theories and proof
  1037 scripts to the new package (backup your sources first!).
  1038 
  1039 
  1040 * HOL/record package: considerably improved implementation; now
  1041 includes concrete syntax for record types, terms, updates; theorems
  1042 for surjective pairing and splitting !!-bound record variables; proof
  1043 support is as follows:
  1044 
  1045   1) standard conversions (selectors or updates applied to record
  1046 constructor terms) are part of the standard simpset;
  1047 
  1048   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1049 made part of standard simpset and claset via addIffs;
  1050 
  1051   3) a tactic for record field splitting (record_split_tac) is part of
  1052 the standard claset (addSWrapper);
  1053 
  1054 To get a better idea about these rules you may retrieve them via
  1055 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1056 the name of your record type.
  1057 
  1058 The split tactic 3) conceptually simplifies by the following rule:
  1059 
  1060   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1061 
  1062 Thus any record variable that is bound by meta-all will automatically
  1063 blow up into some record constructor term, consequently the
  1064 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1065 solve record problems automatically.
  1066 
  1067 
  1068 * reorganized the main HOL image: HOL/Integ and String loaded by
  1069 default; theory Main includes everything;
  1070 
  1071 * automatic simplification of integer sums and comparisons, using cancellation;
  1072 
  1073 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1074 
  1075 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1076 
  1077 * many new identities for unions, intersections, set difference, etc.;
  1078 
  1079 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1080 called split_if, split_split, split_sum_case and split_nat_case (to go
  1081 with add/delsplits);
  1082 
  1083 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1084 (?x::unit) = (); this is made part of the default simpset, which COULD
  1085 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1086 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1087 unit_abs_eta_conv is added in order to counter the effect of
  1088 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1089 %u.f();
  1090 
  1091 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1092 makes more sense);
  1093 
  1094 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1095   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1096   disjointness reasoning but breaking a few old proofs.
  1097 
  1098 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1099 to 'converse' from 'inverse' (for compatibility with ZF and some
  1100 literature);
  1101 
  1102 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1103 the well-founded relation;
  1104 
  1105 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1106     Compl A.  The "Compl" syntax remains available as input syntax for this
  1107     release ONLY.
  1108 
  1109 * HOL/Update: new theory of function updates:
  1110     f(a:=b) == %x. if x=a then b else f x
  1111 may also be iterated as in f(a:=b,c:=d,...);
  1112 
  1113 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1114 
  1115 * HOL/List:
  1116   - new function list_update written xs[i:=v] that updates the i-th
  1117     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1118   - new function `upt' written [i..j(] which generates the list
  1119     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1120     bound write [i..j], which is a shorthand for [i..j+1(].
  1121   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1122 
  1123 * HOL/Arith:
  1124   - removed 'pred' (predecessor) function;
  1125   - generalized some theorems about n-1;
  1126   - many new laws about "div" and "mod";
  1127   - new laws about greatest common divisors (see theory ex/Primes);
  1128 
  1129 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1130 instead of "inverse";
  1131 
  1132 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1133   of the multiset ordering;
  1134 
  1135 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1136   (not included by default);
  1137 
  1138 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1139 
  1140 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1141   programs, i.e. different program variables may have different types.
  1142 
  1143 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1144   [previously, this check worked only if the rewrite rule was unconditional]
  1145   Now rew can involve either definitions or equalities (either == or =).
  1146 
  1147 
  1148 *** ZF ***
  1149 
  1150 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1151   only the theorems proved on ZF.ML;
  1152 
  1153 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1154   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1155   disjointness reasoning but breaking a few old proofs.
  1156 
  1157 * ZF/Update: new theory of function updates
  1158     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1159   may also be iterated as in f(a:=b,c:=d,...);
  1160 
  1161 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1162 
  1163 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1164   [previously, this check worked only if the rewrite rule was unconditional]
  1165   Now rew can involve either definitions or equalities (either == or =).
  1166 
  1167 * case_tac provided for compatibility with HOL
  1168     (like the old excluded_middle_tac, but with subgoals swapped)
  1169 
  1170 
  1171 *** Internal programming interfaces ***
  1172 
  1173 * Pure: several new basic modules made available for general use, see
  1174 also src/Pure/README;
  1175 
  1176 * improved the theory data mechanism to support encapsulation (data
  1177 kind name replaced by private Object.kind, acting as authorization
  1178 key); new type-safe user interface via functor TheoryDataFun; generic
  1179 print_data function becomes basically useless;
  1180 
  1181 * removed global_names compatibility flag -- all theory declarations
  1182 are qualified by default;
  1183 
  1184 * module Pure/Syntax now offers quote / antiquote translation
  1185 functions (useful for Hoare logic etc. with implicit dependencies);
  1186 see HOL/ex/Antiquote for an example use;
  1187 
  1188 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1189 cterm -> thm;
  1190 
  1191 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1192 subgoal;
  1193 
  1194 * Display.print_goals function moved to Locale.print_goals;
  1195 
  1196 * standard print function for goals supports current_goals_markers
  1197 variable for marking begin of proof, end of proof, start of goal; the
  1198 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1199 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1200 for example;
  1201 
  1202 
  1203 
  1204 New in Isabelle98 (January 1998)
  1205 --------------------------------
  1206 
  1207 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1208 
  1209 * changed lexical syntax of terms / types: dots made part of long
  1210 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1211 
  1212 * simpset (and claset) reference variable replaced by functions
  1213 simpset / simpset_ref;
  1214 
  1215 * no longer supports theory aliases (via merge) and non-trivial
  1216 implicit merge of thms' signatures;
  1217 
  1218 * most internal names of constants changed due to qualified names;
  1219 
  1220 * changed Pure/Sequence interface (see Pure/seq.ML);
  1221 
  1222 
  1223 *** General Changes ***
  1224 
  1225 * hierachically structured name spaces (for consts, types, axms, thms
  1226 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1227 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1228 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1229 long_names for fully qualified output names; NOTE: ML programs
  1230 (special tactics, packages etc.) referring to internal names may have
  1231 to be adapted to cope with fully qualified names; in case of severe
  1232 backward campatibility problems try setting 'global_names' at compile
  1233 time to have enrything declared within a flat name space; one may also
  1234 fine tune name declarations in theories via the 'global' and 'local'
  1235 section;
  1236 
  1237 * reimplemented the implicit simpset and claset using the new anytype
  1238 data filed in signatures; references simpset:simpset ref etc. are
  1239 replaced by functions simpset:unit->simpset and
  1240 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1241 to patch your ML files accordingly;
  1242 
  1243 * HTML output now includes theory graph data for display with Java
  1244 applet or isatool browser; data generated automatically via isatool
  1245 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1246 
  1247 * defs may now be conditional; improved rewrite_goals_tac to handle
  1248 conditional equations;
  1249 
  1250 * defs now admits additional type arguments, using TYPE('a) syntax;
  1251 
  1252 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1253 creates a new theory node; implicit merge of thms' signatures is
  1254 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1255 transfer:theory->thm->thm in (rare) cases;
  1256 
  1257 * improved handling of draft signatures / theories; draft thms (and
  1258 ctyps, cterms) are automatically promoted to real ones;
  1259 
  1260 * slightly changed interfaces for oracles: admit many per theory, named
  1261 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1262 
  1263 * print_goals: optional output of const types (set show_consts and
  1264 show_types);
  1265 
  1266 * improved output of warnings (###) and errors (***);
  1267 
  1268 * subgoal_tac displays a warning if the new subgoal has type variables;
  1269 
  1270 * removed old README and Makefiles;
  1271 
  1272 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1273 
  1274 * removed obsolete init_pps and init_database;
  1275 
  1276 * deleted the obsolete tactical STATE, which was declared by
  1277     fun STATE tacfun st = tacfun st st;
  1278 
  1279 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1280 (which abbreviates $HOME);
  1281 
  1282 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1283 use isatool fixseq to adapt your ML programs (this works for fully
  1284 qualified references to the Sequence structure only!);
  1285 
  1286 * use_thy no longer requires writable current directory; it always
  1287 reloads .ML *and* .thy file, if either one is out of date;
  1288 
  1289 
  1290 *** Classical Reasoner ***
  1291 
  1292 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1293 tactics that use classical reasoning to simplify a subgoal without
  1294 splitting it into several subgoals;
  1295 
  1296 * Safe_tac: like safe_tac but uses the default claset;
  1297 
  1298 
  1299 *** Simplifier ***
  1300 
  1301 * added simplification meta rules:
  1302     (asm_)(full_)simplify: simpset -> thm -> thm;
  1303 
  1304 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1305 logics (again);
  1306 
  1307 * added prems argument to simplification procedures;
  1308 
  1309 * HOL, FOL, ZF: added infix function `addsplits':
  1310   instead of `<simpset> setloop (split_tac <thms>)'
  1311   you can simply write `<simpset> addsplits <thms>'
  1312 
  1313 
  1314 *** Syntax ***
  1315 
  1316 * TYPE('a) syntax for type reflection terms;
  1317 
  1318 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1319 
  1320 * pretty printer: changed order of mixfix annotation preference (again!);
  1321 
  1322 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1323 
  1324 
  1325 *** HOL ***
  1326 
  1327 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1328   with `addloop' of the simplifier to faciliate case splitting in premises.
  1329 
  1330 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1331 
  1332 * HOL/Auth: new protocol proofs including some for the Internet
  1333   protocol TLS;
  1334 
  1335 * HOL/Map: new theory of `maps' a la VDM;
  1336 
  1337 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1338 cancelling out common nat summands from =, <, <= (in)equalities, or
  1339 differences; simplification procedures nat_cancel_factor for
  1340 cancelling common factor from =, <, <= (in)equalities over natural
  1341 sums; nat_cancel contains both kinds of procedures, it is installed by
  1342 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1343 
  1344 * HOL/simplifier: terms of the form
  1345   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1346   are rewritten to
  1347   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1348   and those of the form
  1349   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1350   are rewritten to
  1351   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1352 
  1353 * HOL/datatype
  1354   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1355 
  1356   P(t_case f1 ... fn x) =
  1357      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1358         ...
  1359        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1360      )
  1361 
  1362   and a theorem `split_t_case_asm' of the form
  1363 
  1364   P(t_case f1 ... fn x) =
  1365     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1366         ...
  1367        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1368      )
  1369   which can be added to a simpset via `addsplits'. The existing theorems
  1370   expand_list_case and expand_option_case have been renamed to
  1371   split_list_case and split_option_case.
  1372 
  1373 * HOL/Arithmetic:
  1374   - `pred n' is automatically converted to `n-1'.
  1375     Users are strongly encouraged not to use `pred' any longer,
  1376     because it will disappear altogether at some point.
  1377   - Users are strongly encouraged to write "0 < n" rather than
  1378     "n ~= 0". Theorems and proof tools have been modified towards this
  1379     `standard'.
  1380 
  1381 * HOL/Lists:
  1382   the function "set_of_list" has been renamed "set" (and its theorems too);
  1383   the function "nth" now takes its arguments in the reverse order and
  1384   has acquired the infix notation "!" as in "xs!n".
  1385 
  1386 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1387 
  1388 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1389   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1390 
  1391 * HOL/record: extensible records with schematic structural subtyping
  1392 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1393 still lacks various theorems and concrete record syntax;
  1394 
  1395 
  1396 *** HOLCF ***
  1397 
  1398 * removed "axioms" and "generated by" sections;
  1399 
  1400 * replaced "ops" section by extended "consts" section, which is capable of
  1401   handling the continuous function space "->" directly;
  1402 
  1403 * domain package:
  1404   . proves theorems immediately and stores them in the theory,
  1405   . creates hierachical name space,
  1406   . now uses normal mixfix annotations (instead of cinfix...),
  1407   . minor changes to some names and values (for consistency),
  1408   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1409   . separator between mutual domain defs: changed "," to "and",
  1410   . improved handling of sort constraints;  now they have to
  1411     appear on the left-hand side of the equations only;
  1412 
  1413 * fixed LAM <x,y,zs>.b syntax;
  1414 
  1415 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1416 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1417 
  1418 
  1419 *** FOL and ZF ***
  1420 
  1421 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1422   with `addloop' of the simplifier to faciliate case splitting in premises.
  1423 
  1424 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1425 in HOL, they strip ALL and --> from proved theorems;
  1426 
  1427 
  1428 
  1429 New in Isabelle94-8 (May 1997)
  1430 ------------------------------
  1431 
  1432 *** General Changes ***
  1433 
  1434 * new utilities to build / run / maintain Isabelle etc. (in parts
  1435 still somewhat experimental); old Makefiles etc. still functional;
  1436 
  1437 * new 'Isabelle System Manual';
  1438 
  1439 * INSTALL text, together with ./configure and ./build scripts;
  1440 
  1441 * reimplemented type inference for greater efficiency, better error
  1442 messages and clean internal interface;
  1443 
  1444 * prlim command for dealing with lots of subgoals (an easier way of
  1445 setting goals_limit);
  1446 
  1447 
  1448 *** Syntax ***
  1449 
  1450 * supports alternative (named) syntax tables (parser and pretty
  1451 printer); internal interface is provided by add_modesyntax(_i);
  1452 
  1453 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1454 be used in conjunction with the Isabelle symbol font; uses the
  1455 "symbols" syntax table;
  1456 
  1457 * added token_translation interface (may translate name tokens in
  1458 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1459 the current print_mode); IMPORTANT: user print translation functions
  1460 are responsible for marking newly introduced bounds
  1461 (Syntax.mark_boundT);
  1462 
  1463 * token translations for modes "xterm" and "xterm_color" that display
  1464 names in bold, underline etc. or colors (which requires a color
  1465 version of xterm);
  1466 
  1467 * infixes may now be declared with names independent of their syntax;
  1468 
  1469 * added typed_print_translation (like print_translation, but may
  1470 access type of constant);
  1471 
  1472 
  1473 *** Classical Reasoner ***
  1474 
  1475 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  1476 some limitations.  Blast_tac...
  1477   + ignores addss, addbefore, addafter; this restriction is intrinsic
  1478   + ignores elimination rules that don't have the correct format
  1479         (the conclusion MUST be a formula variable)
  1480   + ignores types, which can make HOL proofs fail
  1481   + rules must not require higher-order unification, e.g. apply_type in ZF
  1482     [message "Function Var's argument not a bound variable" relates to this]
  1483   + its proof strategy is more general but can actually be slower
  1484 
  1485 * substitution with equality assumptions no longer permutes other
  1486 assumptions;
  1487 
  1488 * minor changes in semantics of addafter (now called addaltern); renamed
  1489 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  1490 (and access functions for it);
  1491 
  1492 * improved combination of classical reasoner and simplifier:
  1493   + functions for handling clasimpsets
  1494   + improvement of addss: now the simplifier is called _after_ the
  1495     safe steps.
  1496   + safe variant of addss called addSss: uses safe simplifications
  1497     _during_ the safe steps. It is more complete as it allows multiple
  1498     instantiations of unknowns (e.g. with slow_tac).
  1499 
  1500 *** Simplifier ***
  1501 
  1502 * added interface for simplification procedures (functions that
  1503 produce *proven* rewrite rules on the fly, depending on current
  1504 redex);
  1505 
  1506 * ordering on terms as parameter (used for ordered rewriting);
  1507 
  1508 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  1509 
  1510 * the solver is now split into a safe and an unsafe part.
  1511 This should be invisible for the normal user, except that the
  1512 functions setsolver and addsolver have been renamed to setSolver and
  1513 addSolver; added safe_asm_full_simp_tac;
  1514 
  1515 
  1516 *** HOL ***
  1517 
  1518 * a generic induction tactic `induct_tac' which works for all datatypes and
  1519 also for type `nat';
  1520 
  1521 * a generic case distinction tactic `exhaust_tac' which works for all
  1522 datatypes and also for type `nat';
  1523 
  1524 * each datatype comes with a function `size';
  1525 
  1526 * patterns in case expressions allow tuple patterns as arguments to
  1527 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1528 
  1529 * primrec now also works with type nat;
  1530 
  1531 * recdef: a new declaration form, allows general recursive functions to be
  1532 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1533 
  1534 * the constant for negation has been renamed from "not" to "Not" to
  1535 harmonize with FOL, ZF, LK, etc.;
  1536 
  1537 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1538 infinite lists;
  1539 
  1540 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1541 
  1542 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1543 problems in commutative rings, using axiomatic type classes for + and *;
  1544 
  1545 * more examples in HOL/MiniML and HOL/Auth;
  1546 
  1547 * more default rewrite rules for quantifiers, union/intersection;
  1548 
  1549 * a new constant `arbitrary == @x.False';
  1550 
  1551 * HOLCF/IOA replaces old HOL/IOA;
  1552 
  1553 * HOLCF changes: derived all rules and arities
  1554   + axiomatic type classes instead of classes
  1555   + typedef instead of faking type definitions
  1556   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1557   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1558   + eliminated the types void, one, tr
  1559   + use unit lift and bool lift (with translations) instead of one and tr
  1560   + eliminated blift from Lift3.thy (use Def instead of blift)
  1561   all eliminated rules are derived as theorems --> no visible changes ;
  1562 
  1563 
  1564 *** ZF ***
  1565 
  1566 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1567 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1568 as ZF_cs addSIs [equalityI];
  1569 
  1570 
  1571 
  1572 New in Isabelle94-7 (November 96)
  1573 ---------------------------------
  1574 
  1575 * allowing negative levels (as offsets) in prlev and choplev;
  1576 
  1577 * super-linear speedup for large simplifications;
  1578 
  1579 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1580 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1581 FAIL); can suppress it using the command Delsimps (ex_simps @
  1582 all_simps); De Morgan laws are also now included, by default;
  1583 
  1584 * improved printing of ==>  :  ~:
  1585 
  1586 * new object-logic "Sequents" adds linear logic, while replacing LK
  1587 and Modal (thanks to Sara Kalvala);
  1588 
  1589 * HOL/Auth: correctness proofs for authentication protocols;
  1590 
  1591 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1592 examples on HOL/Auth);
  1593 
  1594 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1595 the rewriter and classical reasoner simultaneously;
  1596 
  1597 * function uresult no longer returns theorems in "standard" format;
  1598 regain previous version by: val uresult = standard o uresult;
  1599 
  1600 
  1601 
  1602 New in Isabelle94-6
  1603 -------------------
  1604 
  1605 * oracles -- these establish an interface between Isabelle and trusted
  1606 external reasoners, which may deliver results as theorems;
  1607 
  1608 * proof objects (in particular record all uses of oracles);
  1609 
  1610 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1611 
  1612 * "constdefs" section in theory files;
  1613 
  1614 * "primrec" section (HOL) no longer requires names;
  1615 
  1616 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1617 
  1618 
  1619 
  1620 New in Isabelle94-5
  1621 -------------------
  1622 
  1623 * reduced space requirements;
  1624 
  1625 * automatic HTML generation from theories;
  1626 
  1627 * theory files no longer require "..." (quotes) around most types;
  1628 
  1629 * new examples, including two proofs of the Church-Rosser theorem;
  1630 
  1631 * non-curried (1994) version of HOL is no longer distributed;
  1632 
  1633 
  1634 
  1635 New in Isabelle94-4
  1636 -------------------
  1637 
  1638 * greatly reduced space requirements;
  1639 
  1640 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1641 
  1642 * searchable theorem database (see the section "Retrieving theorems" on
  1643 page 8 of the Reference Manual);
  1644 
  1645 * new examples, including Grabczewski's monumental case study of the
  1646 Axiom of Choice;
  1647 
  1648 * The previous version of HOL renamed to Old_HOL;
  1649 
  1650 * The new version of HOL (previously called CHOL) uses a curried syntax
  1651 for functions.  Application looks like f a b instead of f(a,b);
  1652 
  1653 * Mutually recursive inductive definitions finally work in HOL;
  1654 
  1655 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1656 translates to the operator "split";
  1657 
  1658 
  1659 
  1660 New in Isabelle94-3
  1661 -------------------
  1662 
  1663 * new infix operator, addss, allowing the classical reasoner to
  1664 perform simplification at each step of its search.  Example:
  1665         fast_tac (cs addss ss)
  1666 
  1667 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1668 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1669 look like (a,b) instead of <a,b>;
  1670 
  1671 * PLEASE NOTE: CHOL will eventually replace HOL!
  1672 
  1673 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1674 It translates to the operator "split".  A new theory of integers is available;
  1675 
  1676 * In ZF, integer numerals now denote two's-complement binary integers.
  1677 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1678 
  1679 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1680 of the Axiom of Choice;
  1681 
  1682 
  1683 
  1684 New in Isabelle94-2
  1685 -------------------
  1686 
  1687 * Significantly faster resolution;
  1688 
  1689 * the different sections in a .thy file can now be mixed and repeated
  1690 freely;
  1691 
  1692 * Database of theorems for FOL, HOL and ZF.  New
  1693 commands including qed, qed_goal and bind_thm store theorems in the database.
  1694 
  1695 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1696 a given theory (thms_of), or find out what theory a theorem was proved in
  1697 (theory_of_thm);
  1698 
  1699 * Bugs fixed in the inductive definition and datatype packages;
  1700 
  1701 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1702 and HOL_dup_cs obsolete;
  1703 
  1704 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1705 have been removed;
  1706 
  1707 * Simpler definition of function space in ZF;
  1708 
  1709 * new results about cardinal and ordinal arithmetic in ZF;
  1710 
  1711 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1712 types;
  1713 
  1714 
  1715 $Id$