NEWS
author nipkow
Mon Jan 29 22:25:45 2001 +0100 (2001-01-29)
changeset 10995 ef0b521698b7
parent 10976 0e7cf6f9fa29
child 10998 fece8333adfc
permissions -rw-r--r--
*** empty log message ***
     1 
     2 Isabelle NEWS -- history user-relevant changes
     3 ==============================================
     4 
     5 *** Overview of INCOMPATIBILITIES ***
     6 
     7 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
     8 operation;
     9 
    10 * HOL: induct renamed to lfp_induct;
    11 
    12 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
    13 
    14 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
    15 relation); infix "^^" has been renamed "``"; infix "``" has been
    16 renamed "`"; "univalent" has been renamed "single_valued";
    17 
    18 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
    19 
    20 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
    21 
    22 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
    23 consequence, it is no longer monotonic wrt. the local goal context
    24 (which is now passed through the inductive cases);
    25 
    26 * Document preparation: renamed standard symbols \<ll> to \<lless> and
    27 \<gg> to \<ggreater>;
    28 
    29 
    30 *** Document preparation ***
    31 
    32 * improved isabelle style files; more abstract symbol implementation
    33 (should now use \isamath{...} and \isatext{...} in custom symbol
    34 definitions);
    35 
    36 * \isabellestyle{NAME} selects version of Isabelle output (currently
    37 available: are "it" for near math-mode best-style output, "sl" for
    38 slanted text style, and "tt" for plain type-writer; if no
    39 \isabellestyle command is given, output is according to slanted
    40 type-writer);
    41 
    42 * support sub/super scripts (for single symbols only), input syntax is
    43 like this: "A\<^sup>*" or "A\<^sup>\<star>";
    44 
    45 * some more standard symbols; see Appendix A of the system manual for
    46 the complete list;
    47 
    48 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
    49 state; Note that presentation of goal states does not conform to
    50 actual human-readable proof documents.  Please do not include goal
    51 states into document output unless you really know what you are doing!
    52 
    53 * isatool unsymbolize tunes sources for plain ASCII communication;
    54 
    55 
    56 *** Isar ***
    57 
    58 * Pure: Isar now suffers initial goal statements to contain unbound
    59 schematic variables (this does not conform to actual readable proof
    60 documents, due to unpredictable outcome and non-compositional proof
    61 checking); users who know what they are doing may use schematic goals
    62 for Prolog-style synthesis of proven results;
    63 
    64 * Pure: assumption method (an implicit finishing) now handles actual
    65 rules as well;
    66 
    67 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
    68 initial goal, declare "that" only as Pure intro (only for single
    69 steps); the "that" rule assumption may now be involved in implicit
    70 finishing, thus ".." becomes a feasible for trivial obtains;
    71 
    72 * Pure: default proof step now includes 'intro_classes'; thus trivial
    73 instance proofs may be performed by "..";
    74 
    75 * Pure: ?thesis / ?this / "..." now work for pure meta-level
    76 statements as well;
    77 
    78 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
    79 rule (as well as the assumption rule);
    80 
    81 * Pure: 'thm_deps' command visualizes dependencies of theorems and
    82 lemmas, using the graph browser tool;
    83 
    84 * Pure: predict failure of "show" in interactive mode;
    85 
    86 * HOL: improved method 'induct' --- now handles non-atomic goals
    87 (potential INCOMPATIBILITY); tuned error handling;
    88 
    89 * HOL: cases and induct rules now provide explicit hints about the
    90 number of facts to be consumed (0 for "type" and 1 for "set" rules);
    91 any remaining facts are inserted into the goal verbatim;
    92 
    93 * HOL: local contexts (aka cases) may now contain term bindings as
    94 well; the 'cases' and 'induct' methods new provide a ?case binding for
    95 the result to be shown in each case;
    96 
    97 * HOL: added 'recdef_tc' command;
    98 
    99 
   100 *** HOL ***
   101 
   102 * HOL/Library: a collection of generic theories to be used together
   103 with main HOL; the theory loader path already includes this directory
   104 by default; the following existing theories have been moved here:
   105 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   106 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   107 
   108 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   109 modelling and verification task performed in Isabelle/HOL +
   110 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   111 
   112 * HOL basics: added overloaded operations "inverse" and "divide"
   113 (infix "/"), syntax for generic "abs" operation, generic summation
   114 operator;
   115 
   116 * HOL/typedef: simplified package, provide more useful rules (see also
   117 HOL/subset.thy);
   118 
   119 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   120 now expressed as a proper nested rule (old-style tactic scripts may
   121 require atomize_strip_tac to cope with non-atomic premises);
   122 
   123 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   124 to "split_conv" (old name still available for compatibility);
   125 
   126 * HOL: improved concrete syntax for strings (e.g. allows translation
   127 rules with string literals);
   128 
   129 * HOL-Hyperreal: a new target, extending HOL-Real with the hyperreals
   130 and Fleuriot's mechanization of analysis;
   131 
   132 * HOL-Real, HOL-Hyperreals: improved arithmetic simplification;
   133 
   134 
   135 *** CTT ***
   136 
   137 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   138 "lam" is displayed as TWO lambda-symbols
   139 
   140 * CTT: theory Main now available, containing everything (that is, Bool
   141 and Arith);
   142 
   143 
   144 *** General ***
   145 
   146 * print modes "brackets" and "no_brackets" control output of nested =>
   147 (types) and ==> (props); the default behaviour is "brackets";
   148 
   149 * system: support Poly/ML 4.0 (current beta versions);
   150 
   151 * Pure: the Simplifier has been implemented properly as a derived rule
   152 outside of the actual kernel (at last!); the overall performance
   153 penalty in practical applications is about 50%, while reliability of
   154 the Isabelle inference kernel has been greatly improved;
   155 
   156 * Provers: fast_tac (and friends) now handle actual object-logic rules
   157 as assumptions as well;
   158 
   159 
   160 
   161 New in Isabelle99-1 (October 2000)
   162 ----------------------------------
   163 
   164 *** Overview of INCOMPATIBILITIES ***
   165 
   166 * HOL: simplification of natural numbers is much changed; to partly
   167 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   168 issue the following ML commands:
   169 
   170   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   171   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   172 
   173 * HOL: simplification no longer dives into case-expressions; this is
   174 controlled by "t.weak_case_cong" for each datatype t;
   175 
   176 * HOL: nat_less_induct renamed to less_induct;
   177 
   178 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   179 fixsome to patch .thy and .ML sources automatically;
   180 
   181   select_equality  -> some_equality
   182   select_eq_Ex     -> some_eq_ex
   183   selectI2EX       -> someI2_ex
   184   selectI2         -> someI2
   185   selectI          -> someI
   186   select1_equality -> some1_equality
   187   Eps_sym_eq       -> some_sym_eq_trivial
   188   Eps_eq           -> some_eq_trivial
   189 
   190 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   191 
   192 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   193 instead);
   194 
   195 * HOL: the recursion equations generated by 'recdef' are now called
   196 f.simps instead of f.rules;
   197 
   198 * HOL: qed_spec_mp now also handles bounded ALL as well;
   199 
   200 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   201 sometimes be needed;
   202 
   203 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   204 
   205 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   206 
   207 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   208 product is now "<*>" instead of "Times"; the lexicographic product is
   209 now "<*lex*>" instead of "**";
   210 
   211 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   212 of main HOL, but was unused); better use HOL's datatype package;
   213 
   214 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   215 the old syntax may be recovered as follows:
   216 
   217   syntax (symbols)
   218     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   219       (infixl "\\<oplus>" 100)
   220 
   221 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   222 
   223 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   224 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   225 internally;
   226 
   227 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   228 changed from A/r to A//r;
   229 
   230 * ZF: new treatment of arithmetic (nat & int) may break some old
   231 proofs;
   232 
   233 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   234 rulify -> rule_format, elimify -> elim_format, ...);
   235 
   236 * Isar/Provers: intro/elim/dest attributes changed; renamed
   237 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   238 should have to change intro!! to intro? only); replaced "delrule" by
   239 "rule del";
   240 
   241 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   242 
   243 * Provers: strengthened force_tac by using new first_best_tac;
   244 
   245 * LaTeX document preparation: several changes of isabelle.sty (see
   246 lib/texinputs);
   247 
   248 
   249 *** Document preparation ***
   250 
   251 * formal comments (text blocks etc.) in new-style theories may now
   252 contain antiquotations of thm/prop/term/typ/text to be presented
   253 according to latex print mode; concrete syntax is like this:
   254 @{term[show_types] "f(x) = a + x"};
   255 
   256 * isatool mkdir provides easy setup of Isabelle session directories,
   257 including proper document sources;
   258 
   259 * generated LaTeX sources are now deleted after successful run
   260 (isatool document -c); may retain a copy somewhere else via -D option
   261 of isatool usedir;
   262 
   263 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   264 style files, achieving self-contained LaTeX sources and simplifying
   265 LaTeX debugging;
   266 
   267 * old-style theories now produce (crude) LaTeX output as well;
   268 
   269 * browser info session directories are now self-contained (may be put
   270 on WWW server seperately); improved graphs of nested sessions; removed
   271 graph for 'all sessions';
   272 
   273 * several improvements in isabelle style files; \isabellestyle{it}
   274 produces fake math mode output; \isamarkupheader is now \section by
   275 default; see lib/texinputs/isabelle.sty etc.;
   276 
   277 
   278 *** Isar ***
   279 
   280 * Isar/Pure: local results and corresponding term bindings are now
   281 subject to Hindley-Milner polymorphism (similar to ML); this
   282 accommodates incremental type-inference very nicely;
   283 
   284 * Isar/Pure: new derived language element 'obtain' supports
   285 generalized existence reasoning;
   286 
   287 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   288 support accumulation of results, without applying any rules yet;
   289 useful to collect intermediate results without explicit name
   290 references, and for use with transitivity rules with more than 2
   291 premises;
   292 
   293 * Isar/Pure: scalable support for case-analysis type proofs: new
   294 'case' language element refers to local contexts symbolically, as
   295 produced by certain proof methods; internally, case names are attached
   296 to theorems as "tags";
   297 
   298 * Isar/Pure: theory command 'hide' removes declarations from
   299 class/type/const name spaces;
   300 
   301 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   302 indicate potential overloading;
   303 
   304 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   305 
   306 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   307 "{a,b,c}" instead of {a,b,c};
   308 
   309 * Isar/Pure now provides its own version of intro/elim/dest
   310 attributes; useful for building new logics, but beware of confusion
   311 with the version in Provers/classical;
   312 
   313 * Isar/Pure: the local context of (non-atomic) goals is provided via
   314 case name 'antecedent';
   315 
   316 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   317 to the current context is now done automatically);
   318 
   319 * Isar/Pure: theory command 'method_setup' provides a simple interface
   320 for definining proof methods in ML;
   321 
   322 * Isar/Provers: intro/elim/dest attributes changed; renamed
   323 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   324 most cases, one should have to change intro!! to intro? only);
   325 replaced "delrule" by "rule del";
   326 
   327 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   328 'symmetric' attribute (the latter supercedes [RS sym]);
   329 
   330 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   331 method modifier); 'simp' method: 'only:' modifier removes loopers as
   332 well (including splits);
   333 
   334 * Isar/Provers: Simplifier and Classical methods now support all kind
   335 of modifiers used in the past, including 'cong', 'iff', etc.
   336 
   337 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   338 of Simplifier and Classical reasoner);
   339 
   340 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   341 now support named cases; major packages (inductive, datatype, primrec,
   342 recdef) support case names and properly name parameters;
   343 
   344 * Isar/HOL: new transitivity rules for substitution in inequalities --
   345 monotonicity conditions are extracted to be proven at end of
   346 calculations;
   347 
   348 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   349 method anyway;
   350 
   351 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   352 split_if split_if_asm; datatype package provides theorems foo.splits =
   353 foo.split foo.split_asm for each datatype;
   354 
   355 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   356 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   357 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   358 use "(cases (simplified))" method in proper proof texts);
   359 
   360 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   361 
   362 * Isar: names of theorems etc. may be natural numbers as well;
   363 
   364 * Isar: 'pr' command: optional arguments for goals_limit and
   365 ProofContext.prems_limit; no longer prints theory contexts, but only
   366 proof states;
   367 
   368 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   369 additional print modes to be specified; e.g. "pr(latex)" will print
   370 proof state according to the Isabelle LaTeX style;
   371 
   372 * Isar: improved support for emulating tactic scripts, including proof
   373 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   374 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   375 (for HOL datatypes);
   376 
   377 * Isar: simplified (more robust) goal selection of proof methods: 1st
   378 goal, all goals, or explicit goal specifier (tactic emulation); thus
   379 'proof method scripts' have to be in depth-first order;
   380 
   381 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   382 
   383 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   384 should instead use individual commands for printing items
   385 (print_commands, print_methods etc.);
   386 
   387 * Isar: added 'nothing' --- the empty list of theorems;
   388 
   389 
   390 *** HOL ***
   391 
   392 * HOL/MicroJava: formalization of a fragment of Java, together with a
   393 corresponding virtual machine and a specification of its bytecode
   394 verifier and a lightweight bytecode verifier, including proofs of
   395 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   396 Cornelia Pusch (see also the homepage of project Bali at
   397 http://isabelle.in.tum.de/Bali/);
   398 
   399 * HOL/Algebra: new theory of rings and univariate polynomials, by
   400 Clemens Ballarin;
   401 
   402 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   403 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   404 Rasmussen;
   405 
   406 * HOL/Lattice: fundamental concepts of lattice theory and order
   407 structures, including duals, properties of bounds versus algebraic
   408 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   409 Theorem for complete lattices etc.; may also serve as a demonstration
   410 for abstract algebraic reasoning using axiomatic type classes, and
   411 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   412 
   413 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   414 von Oheimb;
   415 
   416 * HOL/IMPP: extension of IMP with local variables and mutually
   417 recursive procedures, by David von Oheimb;
   418 
   419 * HOL/Lambda: converted into new-style theory and document;
   420 
   421 * HOL/ex/Multiquote: example of multiple nested quotations and
   422 anti-quotations -- basically a generalized version of de-Bruijn
   423 representation; very useful in avoiding lifting of operations;
   424 
   425 * HOL/record: added general record equality rule to simpset; fixed
   426 select-update simplification procedure to handle extended records as
   427 well; admit "r" as field name;
   428 
   429 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   430 other numeric types and also as the identity of groups, rings, etc.;
   431 
   432 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   433 Types nat and int belong to this axclass;
   434 
   435 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   436    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   437    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   438   two terms #m*u and #n*u are replaced by #(m+n)*u
   439     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   440   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   441     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   442 
   443 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   444 powerful prover for predicate logic but knows nothing of clasets; see
   445 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   446 
   447 * HOL: new version of "case_tac" subsumes both boolean case split and
   448 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   449 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   450 
   451 * HOL: simplification no longer dives into case-expressions: only the
   452 selector expression is simplified, but not the remaining arms; to
   453 enable full simplification of case-expressions for datatype t, you may
   454 remove t.weak_case_cong from the simpset, either globally (Delcongs
   455 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   456 
   457 * HOL/recdef: the recursion equations generated by 'recdef' for
   458 function 'f' are now called f.simps instead of f.rules; if all
   459 termination conditions are proved automatically, these simplification
   460 rules are added to the simpset, as in primrec; rules may be named
   461 individually as well, resulting in a separate list of theorems for
   462 each equation;
   463 
   464 * HOL/While is a new theory that provides a while-combinator. It
   465 permits the definition of tail-recursive functions without the
   466 provision of a termination measure. The latter is necessary once the
   467 invariant proof rule for while is applied.
   468 
   469 * HOL: new (overloaded) notation for the set of elements below/above
   470 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   471 
   472 * HOL: theorems impI, allI, ballI bound as "strip";
   473 
   474 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   475 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   476 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   477 
   478 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   479 
   480 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   481 main HOL, but was unused);
   482 
   483 * HOL: fewer consts declared as global (e.g. have to refer to
   484 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   485 
   486 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   487 in case of overlap with user translations (e.g. judgements over
   488 tuples); (note that the underlying logical represenation is still
   489 bogus);
   490 
   491 
   492 *** ZF ***
   493 
   494 * ZF: simplification automatically cancels common terms in arithmetic
   495 expressions over nat and int;
   496 
   497 * ZF: new treatment of nat to minimize type-checking: all operators
   498 coerce their operands to a natural number using the function natify,
   499 making the algebraic laws unconditional;
   500 
   501 * ZF: as above, for int: operators coerce their operands to an integer
   502 using the function intify;
   503 
   504 * ZF: the integer library now contains many of the usual laws for the
   505 orderings, including $<=, and monotonicity laws for $+ and $*;
   506 
   507 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
   508 simplification;
   509 
   510 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
   511 to the simplifier and classical reasoner simultaneously;
   512 
   513 
   514 *** General ***
   515 
   516 * Provers: blast_tac now handles actual object-logic rules as
   517 assumptions; note that auto_tac uses blast_tac internally as well;
   518 
   519 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
   520 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
   521 
   522 * Provers: delrules now handles destruct rules as well (no longer need
   523 explicit make_elim);
   524 
   525 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
   526   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   527 use instead the strong form,
   528   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   529 in HOL, FOL and ZF the function cla_make_elim will create such rules
   530 from destruct-rules;
   531 
   532 * Provers: Simplifier.easy_setup provides a fast path to basic
   533 Simplifier setup for new object-logics;
   534 
   535 * Pure: AST translation rules no longer require constant head on LHS;
   536 
   537 * Pure: improved name spaces: ambiguous output is qualified; support
   538 for hiding of names;
   539 
   540 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
   541 XSYMBOL_HOME; no longer need to do manual configuration in most
   542 situations;
   543 
   544 * system: compression of ML heaps images may now be controlled via -c
   545 option of isabelle and isatool usedir (currently only observed by
   546 Poly/ML);
   547 
   548 * system: isatool installfonts may handle X-Symbol fonts as well (very
   549 useful for remote X11);
   550 
   551 * system: provide TAGS file for Isabelle sources;
   552 
   553 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
   554 order;
   555 
   556 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
   557 timing flag supersedes proof_timing and Toplevel.trace;
   558 
   559 * ML: new combinators |>> and |>>> for incremental transformations
   560 with secondary results (e.g. certain theory extensions):
   561 
   562 * ML: PureThy.add_defs gets additional argument to indicate potential
   563 overloading (usually false);
   564 
   565 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
   566 results;
   567 
   568 
   569 
   570 New in Isabelle99 (October 1999)
   571 --------------------------------
   572 
   573 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   574 
   575 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
   576 are no longer simplified.  (This allows the simplifier to unfold recursive
   577 functional programs.)  To restore the old behaviour, declare
   578 
   579     Delcongs [if_weak_cong];
   580 
   581 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
   582 complement;
   583 
   584 * HOL: the predicate "inj" is now defined by translation to "inj_on";
   585 
   586 * HOL/datatype: mutual_induct_tac no longer exists --
   587   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
   588 
   589 * HOL/typedef: fixed type inference for representing set; type
   590 arguments now have to occur explicitly on the rhs as type constraints;
   591 
   592 * ZF: The con_defs part of an inductive definition may no longer refer
   593 to constants declared in the same theory;
   594 
   595 * HOL, ZF: the function mk_cases, generated by the inductive
   596 definition package, has lost an argument.  To simplify its result, it
   597 uses the default simpset instead of a supplied list of theorems.
   598 
   599 * HOL/List: the constructors of type list are now Nil and Cons;
   600 
   601 * Simplifier: the type of the infix ML functions
   602         setSSolver addSSolver setSolver addSolver
   603 is now  simpset * solver -> simpset  where `solver' is a new abstract type
   604 for packaging solvers. A solver is created via
   605         mk_solver: string -> (thm list -> int -> tactic) -> solver
   606 where the string argument is only a comment.
   607 
   608 
   609 *** Proof tools ***
   610 
   611 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
   612 decision procedure for linear arithmetic. Currently it is used for
   613 types `nat', `int', and `real' in HOL (see below); it can, should and
   614 will be instantiated for other types and logics as well.
   615 
   616 * The simplifier now accepts rewrite rules with flexible heads, eg
   617      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
   618   They are applied like any rule with a non-pattern lhs, i.e. by first-order
   619   matching.
   620 
   621 
   622 *** General ***
   623 
   624 * New Isabelle/Isar subsystem provides an alternative to traditional
   625 tactical theorem proving; together with the ProofGeneral/isar user
   626 interface it offers an interactive environment for developing human
   627 readable proof documents (Isar == Intelligible semi-automated
   628 reasoning); for further information see isatool doc isar-ref,
   629 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
   630 
   631 * improved and simplified presentation of theories: better HTML markup
   632 (including colors), graph views in several sizes; isatool usedir now
   633 provides a proper interface for user theories (via -P option); actual
   634 document preparation based on (PDF)LaTeX is available as well (for
   635 new-style theories only); see isatool doc system for more information;
   636 
   637 * native support for Proof General, both for classic Isabelle and
   638 Isabelle/Isar;
   639 
   640 * ML function thm_deps visualizes dependencies of theorems and lemmas,
   641 using the graph browser tool;
   642 
   643 * Isabelle manuals now also available as PDF;
   644 
   645 * theory loader rewritten from scratch (may not be fully
   646 bug-compatible); old loadpath variable has been replaced by show_path,
   647 add_path, del_path, reset_path functions; new operations such as
   648 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
   649 isatool doc ref);
   650 
   651 * improved isatool install: option -k creates KDE application icon,
   652 option -p DIR installs standalone binaries;
   653 
   654 * added ML_PLATFORM setting (useful for cross-platform installations);
   655 more robust handling of platform specific ML images for SML/NJ;
   656 
   657 * the settings environment is now statically scoped, i.e. it is never
   658 created again in sub-processes invoked from isabelle, isatool, or
   659 Isabelle;
   660 
   661 * path element specification '~~' refers to '$ISABELLE_HOME';
   662 
   663 * in locales, the "assumes" and "defines" parts may be omitted if
   664 empty;
   665 
   666 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   667 long arrows);
   668 
   669 * new print_mode "HTML";
   670 
   671 * new flag show_tags controls display of tags of theorems (which are
   672 basically just comments that may be attached by some tools);
   673 
   674 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   675 mode and goal output format:
   676 
   677 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   678 244c244
   679 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   680 ---
   681 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   682 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   683 181c181
   684 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   685 ---
   686 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   687 
   688 * function bind_thms stores lists of theorems (cf. bind_thm);
   689 
   690 * new shorthand tactics ftac, eatac, datac, fatac;
   691 
   692 * qed (and friends) now accept "" as result name; in that case the
   693 theorem is not stored, but proper checks and presentation of the
   694 result still apply;
   695 
   696 * theorem database now also indexes constants "Trueprop", "all",
   697 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   698 
   699 
   700 *** HOL ***
   701 
   702 ** HOL arithmetic **
   703 
   704 * There are now decision procedures for linear arithmetic over nat and
   705 int:
   706 
   707 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   708 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   709 are treated as atomic; subformulae not involving type `nat' or `int'
   710 are ignored; quantified subformulae are ignored unless they are
   711 positive universal or negative existential. The tactic has to be
   712 invoked by hand and can be a little bit slow. In particular, the
   713 running time is exponential in the number of occurrences of `min' and
   714 `max', and `-' on `nat'.
   715 
   716 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   717 (negated) (in)equalities among the premises and the conclusion into
   718 account (i.e. no compound formulae) and does not know about `min' and
   719 `max', and `-' on `nat'. It is fast and is used automatically by the
   720 simplifier.
   721 
   722 NB: At the moment, these decision procedures do not cope with mixed
   723 nat/int formulae where the two parts interact, such as `m < n ==>
   724 int(m) < int(n)'.
   725 
   726 * HOL/Numeral provides a generic theory of numerals (encoded
   727 efficiently as bit strings); setup for types nat/int/real is in place;
   728 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   729 int, existing theories and proof scripts may require a few additional
   730 type constraints;
   731 
   732 * integer division and remainder can now be performed on constant
   733 arguments;
   734 
   735 * many properties of integer multiplication, division and remainder
   736 are now available;
   737 
   738 * An interface to the Stanford Validity Checker (SVC) is available through the
   739 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   740 are proved automatically.  SVC must be installed separately, and its results
   741 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   742 invocation of the underlying oracle).  For SVC see
   743   http://verify.stanford.edu/SVC
   744 
   745 * IsaMakefile: the HOL-Real target now builds an actual image;
   746 
   747 
   748 ** HOL misc **
   749 
   750 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   751 (in Isabelle/Isar) -- by Gertrud Bauer;
   752 
   753 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   754 analysis for assembly languages with subtypes;
   755 
   756 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   757 -- avoids syntactic ambiguities and treats state, transition, and
   758 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   759 changed syntax and (many) tactics;
   760 
   761 * HOL/inductive: Now also handles more general introduction rules such
   762   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
   763   theorems are now maintained within the theory (maintained via the
   764   "mono" attribute);
   765 
   766 * HOL/datatype: Now also handles arbitrarily branching datatypes
   767   (using function types) such as
   768 
   769   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
   770 
   771 * HOL/record: record_simproc (part of the default simpset) takes care
   772 of selectors applied to updated records; record_split_tac is no longer
   773 part of the default claset; update_defs may now be removed from the
   774 simpset in many cases; COMPATIBILITY: old behavior achieved by
   775 
   776   claset_ref () := claset() addSWrapper record_split_wrapper;
   777   Delsimprocs [record_simproc]
   778 
   779 * HOL/typedef: fixed type inference for representing set; type
   780 arguments now have to occur explicitly on the rhs as type constraints;
   781 
   782 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
   783 names rather than an ML expression;
   784 
   785 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
   786 supplied later.  Program schemes can be defined, such as
   787     "While B C s = (if B s then While B C (C s) else s)"
   788 where the well-founded relation can be chosen after B and C have been given.
   789 
   790 * HOL/List: the constructors of type list are now Nil and Cons;
   791 INCOMPATIBILITY: while [] and infix # syntax is still there, of
   792 course, ML tools referring to List.list.op # etc. have to be adapted;
   793 
   794 * HOL_quantifiers flag superseded by "HOL" print mode, which is
   795 disabled by default; run isabelle with option -m HOL to get back to
   796 the original Gordon/HOL-style output;
   797 
   798 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
   799 ALL x<=y. P, EX x<y. P, EX x<=y. P;
   800 
   801 * HOL basic syntax simplified (more orthogonal): all variants of
   802 All/Ex now support plain / symbolic / HOL notation; plain syntax for
   803 Eps operator is provided as well: "SOME x. P[x]";
   804 
   805 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
   806 
   807 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
   808 thus available for user theories;
   809 
   810 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
   811 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
   812 time;
   813 
   814 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
   815 several times and then mp;
   816 
   817 
   818 *** LK ***
   819 
   820 * the notation <<...>> is now available as a notation for sequences of
   821 formulas;
   822 
   823 * the simplifier is now installed
   824 
   825 * the axiom system has been generalized (thanks to Soren Heilmann)
   826 
   827 * the classical reasoner now has a default rule database
   828 
   829 
   830 *** ZF ***
   831 
   832 * new primrec section allows primitive recursive functions to be given
   833 directly (as in HOL) over datatypes and the natural numbers;
   834 
   835 * new tactics induct_tac and exhaust_tac for induction (or case
   836 analysis) over datatypes and the natural numbers;
   837 
   838 * the datatype declaration of type T now defines the recursor T_rec;
   839 
   840 * simplification automatically does freeness reasoning for datatype
   841 constructors;
   842 
   843 * automatic type-inference, with AddTCs command to insert new
   844 type-checking rules;
   845 
   846 * datatype introduction rules are now added as Safe Introduction rules
   847 to the claset;
   848 
   849 * the syntax "if P then x else y" is now available in addition to
   850 if(P,x,y);
   851 
   852 
   853 *** Internal programming interfaces ***
   854 
   855 * tuned simplifier trace output; new flag debug_simp;
   856 
   857 * structures Vartab / Termtab (instances of TableFun) offer efficient
   858 tables indexed by indexname_ord / term_ord (compatible with aconv);
   859 
   860 * AxClass.axclass_tac lost the theory argument;
   861 
   862 * tuned current_goals_markers semantics: begin / end goal avoids
   863 printing empty lines;
   864 
   865 * removed prs and prs_fn hook, which was broken because it did not
   866 include \n in its semantics, forcing writeln to add one
   867 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
   868 string -> unit if you really want to output text without newline;
   869 
   870 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
   871 plain output, interface builders may have to enable 'isabelle_font'
   872 mode to get Isabelle font glyphs as before;
   873 
   874 * refined token_translation interface; INCOMPATIBILITY: output length
   875 now of type real instead of int;
   876 
   877 * theory loader actions may be traced via new ThyInfo.add_hook
   878 interface (see src/Pure/Thy/thy_info.ML); example application: keep
   879 your own database of information attached to *whole* theories -- as
   880 opposed to intra-theory data slots offered via TheoryDataFun;
   881 
   882 * proper handling of dangling sort hypotheses (at last!);
   883 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
   884 extra sort hypotheses that can be witnessed from the type signature;
   885 the force_strip_shyps flag is gone, any remaining shyps are simply
   886 left in the theorem (with a warning issued by strip_shyps_warning);
   887 
   888 
   889 
   890 New in Isabelle98-1 (October 1998)
   891 ----------------------------------
   892 
   893 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   894 
   895 * several changes of automated proof tools;
   896 
   897 * HOL: major changes to the inductive and datatype packages, including
   898 some minor incompatibilities of theory syntax;
   899 
   900 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
   901 called `inj_on';
   902 
   903 * HOL: removed duplicate thms in Arith:
   904   less_imp_add_less  should be replaced by  trans_less_add1
   905   le_imp_add_le      should be replaced by  trans_le_add1
   906 
   907 * HOL: unary minus is now overloaded (new type constraints may be
   908 required);
   909 
   910 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
   911 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
   912 now taken as an integer constant.
   913 
   914 * Pure: ML function 'theory_of' renamed to 'theory';
   915 
   916 
   917 *** Proof tools ***
   918 
   919 * Simplifier:
   920   1. Asm_full_simp_tac is now more aggressive.
   921      1. It will sometimes reorient premises if that increases their power to
   922         simplify.
   923      2. It does no longer proceed strictly from left to right but may also
   924         rotate premises to achieve further simplification.
   925      For compatibility reasons there is now Asm_lr_simp_tac which is like the
   926      old Asm_full_simp_tac in that it does not rotate premises.
   927   2. The simplifier now knows a little bit about nat-arithmetic.
   928 
   929 * Classical reasoner: wrapper mechanism for the classical reasoner now
   930 allows for selected deletion of wrappers, by introduction of names for
   931 wrapper functionals.  This implies that addbefore, addSbefore,
   932 addaltern, and addSaltern now take a pair (name, tactic) as argument,
   933 and that adding two tactics with the same name overwrites the first
   934 one (emitting a warning).
   935   type wrapper = (int -> tactic) -> (int -> tactic)
   936   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
   937   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
   938   delWrapper, delSWrapper: claset *  string            -> claset
   939   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
   940 
   941 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
   942 semantics; addbefore now affects only the unsafe part of step_tac
   943 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
   944 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
   945 by Force_tac;
   946 
   947 * Classical reasoner: setwrapper to setWrapper and compwrapper to
   948 compWrapper; added safe wrapper (and access functions for it);
   949 
   950 * HOL/split_all_tac is now much faster and fails if there is nothing
   951 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
   952 and the names of the automatically generated variables have changed.
   953 split_all_tac has moved within claset() from unsafe wrappers to safe
   954 wrappers, which means that !!-bound variables are split much more
   955 aggressively, and safe_tac and clarify_tac now split such variables.
   956 If this splitting is not appropriate, use delSWrapper "split_all_tac".
   957 Note: the same holds for record_split_tac, which does the job of
   958 split_all_tac for record fields.
   959 
   960 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
   961 permanently to the default simpset using Addsplits just like
   962 Addsimps. They can be removed via Delsplits just like
   963 Delsimps. Lower-case versions are also available.
   964 
   965 * HOL/Simplifier: The rule split_if is now part of the default
   966 simpset. This means that the simplifier will eliminate all occurrences
   967 of if-then-else in the conclusion of a goal. To prevent this, you can
   968 either remove split_if completely from the default simpset by
   969 `Delsplits [split_if]' or remove it in a specific call of the
   970 simplifier using `... delsplits [split_if]'.  You can also add/delete
   971 other case splitting rules to/from the default simpset: every datatype
   972 generates suitable rules `split_t_case' and `split_t_case_asm' (where
   973 t is the name of the datatype).
   974 
   975 * Classical reasoner / Simplifier combination: new force_tac (and
   976 derivatives Force_tac, force) combines rewriting and classical
   977 reasoning (and whatever other tools) similarly to auto_tac, but is
   978 aimed to solve the given subgoal completely.
   979 
   980 
   981 *** General ***
   982 
   983 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
   984 and `goalw': the theory is no longer needed as an explicit argument -
   985 the current theory context is used; assumptions are no longer returned
   986 at the ML-level unless one of them starts with ==> or !!; it is
   987 recommended to convert to these new commands using isatool fixgoal
   988 (backup your sources first!);
   989 
   990 * new top-level commands 'thm' and 'thms' for retrieving theorems from
   991 the current theory context, and 'theory' to lookup stored theories;
   992 
   993 * new theory section 'locale' for declaring constants, assumptions and
   994 definitions that have local scope;
   995 
   996 * new theory section 'nonterminals' for purely syntactic types;
   997 
   998 * new theory section 'setup' for generic ML setup functions
   999 (e.g. package initialization);
  1000 
  1001 * the distribution now includes Isabelle icons: see
  1002 lib/logo/isabelle-{small,tiny}.xpm;
  1003 
  1004 * isatool install - install binaries with absolute references to
  1005 ISABELLE_HOME/bin;
  1006 
  1007 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1008 
  1009 * print mode 'emacs' reserved for Isamode;
  1010 
  1011 * support multiple print (ast) translations per constant name;
  1012 
  1013 * theorems involving oracles are now printed with a suffixed [!];
  1014 
  1015 
  1016 *** HOL ***
  1017 
  1018 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1019 
  1020 * HOL/inductive package reorganized and improved: now supports mutual
  1021 definitions such as
  1022 
  1023   inductive EVEN ODD
  1024     intrs
  1025       null "0 : EVEN"
  1026       oddI "n : EVEN ==> Suc n : ODD"
  1027       evenI "n : ODD ==> Suc n : EVEN"
  1028 
  1029 new theorem list "elims" contains an elimination rule for each of the
  1030 recursive sets; inductive definitions now handle disjunctive premises
  1031 correctly (also ZF);
  1032 
  1033 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1034 "mutual_induct" no longer exists - the induction rule is always
  1035 contained in "induct";
  1036 
  1037 
  1038 * HOL/datatype package re-implemented and greatly improved: now
  1039 supports mutually recursive datatypes such as
  1040 
  1041   datatype
  1042     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1043             | SUM ('a aexp) ('a aexp)
  1044             | DIFF ('a aexp) ('a aexp)
  1045             | NUM 'a
  1046   and
  1047     'a bexp = LESS ('a aexp) ('a aexp)
  1048             | AND ('a bexp) ('a bexp)
  1049             | OR ('a bexp) ('a bexp)
  1050 
  1051 as well as indirectly recursive datatypes such as
  1052 
  1053   datatype
  1054     ('a, 'b) term = Var 'a
  1055                   | App 'b ((('a, 'b) term) list)
  1056 
  1057 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1058 induction on mutually / indirectly recursive datatypes.
  1059 
  1060 Primrec equations are now stored in theory and can be accessed via
  1061 <function_name>.simps.
  1062 
  1063 INCOMPATIBILITIES:
  1064 
  1065   - Theories using datatypes must now have theory Datatype as an
  1066     ancestor.
  1067   - The specific <typename>.induct_tac no longer exists - use the
  1068     generic induct_tac instead.
  1069   - natE has been renamed to nat.exhaust - use exhaust_tac
  1070     instead of res_inst_tac ... natE. Note that the variable
  1071     names in nat.exhaust differ from the names in natE, this
  1072     may cause some "fragile" proofs to fail.
  1073   - The theorems split_<typename>_case and split_<typename>_case_asm
  1074     have been renamed to <typename>.split and <typename>.split_asm.
  1075   - Since default sorts of type variables are now handled correctly,
  1076     some datatype definitions may have to be annotated with explicit
  1077     sort constraints.
  1078   - Primrec definitions no longer require function name and type
  1079     of recursive argument.
  1080 
  1081 Consider using isatool fixdatatype to adapt your theories and proof
  1082 scripts to the new package (backup your sources first!).
  1083 
  1084 
  1085 * HOL/record package: considerably improved implementation; now
  1086 includes concrete syntax for record types, terms, updates; theorems
  1087 for surjective pairing and splitting !!-bound record variables; proof
  1088 support is as follows:
  1089 
  1090   1) standard conversions (selectors or updates applied to record
  1091 constructor terms) are part of the standard simpset;
  1092 
  1093   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1094 made part of standard simpset and claset via addIffs;
  1095 
  1096   3) a tactic for record field splitting (record_split_tac) is part of
  1097 the standard claset (addSWrapper);
  1098 
  1099 To get a better idea about these rules you may retrieve them via
  1100 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1101 the name of your record type.
  1102 
  1103 The split tactic 3) conceptually simplifies by the following rule:
  1104 
  1105   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1106 
  1107 Thus any record variable that is bound by meta-all will automatically
  1108 blow up into some record constructor term, consequently the
  1109 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1110 solve record problems automatically.
  1111 
  1112 
  1113 * reorganized the main HOL image: HOL/Integ and String loaded by
  1114 default; theory Main includes everything;
  1115 
  1116 * automatic simplification of integer sums and comparisons, using cancellation;
  1117 
  1118 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1119 
  1120 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1121 
  1122 * many new identities for unions, intersections, set difference, etc.;
  1123 
  1124 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1125 called split_if, split_split, split_sum_case and split_nat_case (to go
  1126 with add/delsplits);
  1127 
  1128 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1129 (?x::unit) = (); this is made part of the default simpset, which COULD
  1130 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1131 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1132 unit_abs_eta_conv is added in order to counter the effect of
  1133 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1134 %u.f();
  1135 
  1136 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1137 makes more sense);
  1138 
  1139 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1140   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1141   disjointness reasoning but breaking a few old proofs.
  1142 
  1143 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1144 to 'converse' from 'inverse' (for compatibility with ZF and some
  1145 literature);
  1146 
  1147 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1148 the well-founded relation;
  1149 
  1150 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1151     Compl A.  The "Compl" syntax remains available as input syntax for this
  1152     release ONLY.
  1153 
  1154 * HOL/Update: new theory of function updates:
  1155     f(a:=b) == %x. if x=a then b else f x
  1156 may also be iterated as in f(a:=b,c:=d,...);
  1157 
  1158 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1159 
  1160 * HOL/List:
  1161   - new function list_update written xs[i:=v] that updates the i-th
  1162     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1163   - new function `upt' written [i..j(] which generates the list
  1164     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1165     bound write [i..j], which is a shorthand for [i..j+1(].
  1166   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1167 
  1168 * HOL/Arith:
  1169   - removed 'pred' (predecessor) function;
  1170   - generalized some theorems about n-1;
  1171   - many new laws about "div" and "mod";
  1172   - new laws about greatest common divisors (see theory ex/Primes);
  1173 
  1174 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1175 instead of "inverse";
  1176 
  1177 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1178   of the multiset ordering;
  1179 
  1180 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1181   (not included by default);
  1182 
  1183 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1184 
  1185 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1186   programs, i.e. different program variables may have different types.
  1187 
  1188 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1189   [previously, this check worked only if the rewrite rule was unconditional]
  1190   Now rew can involve either definitions or equalities (either == or =).
  1191 
  1192 
  1193 *** ZF ***
  1194 
  1195 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1196   only the theorems proved on ZF.ML;
  1197 
  1198 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1199   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1200   disjointness reasoning but breaking a few old proofs.
  1201 
  1202 * ZF/Update: new theory of function updates
  1203     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1204   may also be iterated as in f(a:=b,c:=d,...);
  1205 
  1206 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1207 
  1208 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1209   [previously, this check worked only if the rewrite rule was unconditional]
  1210   Now rew can involve either definitions or equalities (either == or =).
  1211 
  1212 * case_tac provided for compatibility with HOL
  1213     (like the old excluded_middle_tac, but with subgoals swapped)
  1214 
  1215 
  1216 *** Internal programming interfaces ***
  1217 
  1218 * Pure: several new basic modules made available for general use, see
  1219 also src/Pure/README;
  1220 
  1221 * improved the theory data mechanism to support encapsulation (data
  1222 kind name replaced by private Object.kind, acting as authorization
  1223 key); new type-safe user interface via functor TheoryDataFun; generic
  1224 print_data function becomes basically useless;
  1225 
  1226 * removed global_names compatibility flag -- all theory declarations
  1227 are qualified by default;
  1228 
  1229 * module Pure/Syntax now offers quote / antiquote translation
  1230 functions (useful for Hoare logic etc. with implicit dependencies);
  1231 see HOL/ex/Antiquote for an example use;
  1232 
  1233 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1234 cterm -> thm;
  1235 
  1236 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1237 subgoal;
  1238 
  1239 * Display.print_goals function moved to Locale.print_goals;
  1240 
  1241 * standard print function for goals supports current_goals_markers
  1242 variable for marking begin of proof, end of proof, start of goal; the
  1243 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1244 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1245 for example;
  1246 
  1247 
  1248 
  1249 New in Isabelle98 (January 1998)
  1250 --------------------------------
  1251 
  1252 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1253 
  1254 * changed lexical syntax of terms / types: dots made part of long
  1255 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1256 
  1257 * simpset (and claset) reference variable replaced by functions
  1258 simpset / simpset_ref;
  1259 
  1260 * no longer supports theory aliases (via merge) and non-trivial
  1261 implicit merge of thms' signatures;
  1262 
  1263 * most internal names of constants changed due to qualified names;
  1264 
  1265 * changed Pure/Sequence interface (see Pure/seq.ML);
  1266 
  1267 
  1268 *** General Changes ***
  1269 
  1270 * hierachically structured name spaces (for consts, types, axms, thms
  1271 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1272 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1273 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1274 long_names for fully qualified output names; NOTE: ML programs
  1275 (special tactics, packages etc.) referring to internal names may have
  1276 to be adapted to cope with fully qualified names; in case of severe
  1277 backward campatibility problems try setting 'global_names' at compile
  1278 time to have enrything declared within a flat name space; one may also
  1279 fine tune name declarations in theories via the 'global' and 'local'
  1280 section;
  1281 
  1282 * reimplemented the implicit simpset and claset using the new anytype
  1283 data filed in signatures; references simpset:simpset ref etc. are
  1284 replaced by functions simpset:unit->simpset and
  1285 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1286 to patch your ML files accordingly;
  1287 
  1288 * HTML output now includes theory graph data for display with Java
  1289 applet or isatool browser; data generated automatically via isatool
  1290 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1291 
  1292 * defs may now be conditional; improved rewrite_goals_tac to handle
  1293 conditional equations;
  1294 
  1295 * defs now admits additional type arguments, using TYPE('a) syntax;
  1296 
  1297 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1298 creates a new theory node; implicit merge of thms' signatures is
  1299 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1300 transfer:theory->thm->thm in (rare) cases;
  1301 
  1302 * improved handling of draft signatures / theories; draft thms (and
  1303 ctyps, cterms) are automatically promoted to real ones;
  1304 
  1305 * slightly changed interfaces for oracles: admit many per theory, named
  1306 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1307 
  1308 * print_goals: optional output of const types (set show_consts and
  1309 show_types);
  1310 
  1311 * improved output of warnings (###) and errors (***);
  1312 
  1313 * subgoal_tac displays a warning if the new subgoal has type variables;
  1314 
  1315 * removed old README and Makefiles;
  1316 
  1317 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1318 
  1319 * removed obsolete init_pps and init_database;
  1320 
  1321 * deleted the obsolete tactical STATE, which was declared by
  1322     fun STATE tacfun st = tacfun st st;
  1323 
  1324 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1325 (which abbreviates $HOME);
  1326 
  1327 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1328 use isatool fixseq to adapt your ML programs (this works for fully
  1329 qualified references to the Sequence structure only!);
  1330 
  1331 * use_thy no longer requires writable current directory; it always
  1332 reloads .ML *and* .thy file, if either one is out of date;
  1333 
  1334 
  1335 *** Classical Reasoner ***
  1336 
  1337 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1338 tactics that use classical reasoning to simplify a subgoal without
  1339 splitting it into several subgoals;
  1340 
  1341 * Safe_tac: like safe_tac but uses the default claset;
  1342 
  1343 
  1344 *** Simplifier ***
  1345 
  1346 * added simplification meta rules:
  1347     (asm_)(full_)simplify: simpset -> thm -> thm;
  1348 
  1349 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1350 logics (again);
  1351 
  1352 * added prems argument to simplification procedures;
  1353 
  1354 * HOL, FOL, ZF: added infix function `addsplits':
  1355   instead of `<simpset> setloop (split_tac <thms>)'
  1356   you can simply write `<simpset> addsplits <thms>'
  1357 
  1358 
  1359 *** Syntax ***
  1360 
  1361 * TYPE('a) syntax for type reflection terms;
  1362 
  1363 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1364 
  1365 * pretty printer: changed order of mixfix annotation preference (again!);
  1366 
  1367 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1368 
  1369 
  1370 *** HOL ***
  1371 
  1372 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1373   with `addloop' of the simplifier to faciliate case splitting in premises.
  1374 
  1375 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1376 
  1377 * HOL/Auth: new protocol proofs including some for the Internet
  1378   protocol TLS;
  1379 
  1380 * HOL/Map: new theory of `maps' a la VDM;
  1381 
  1382 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1383 cancelling out common nat summands from =, <, <= (in)equalities, or
  1384 differences; simplification procedures nat_cancel_factor for
  1385 cancelling common factor from =, <, <= (in)equalities over natural
  1386 sums; nat_cancel contains both kinds of procedures, it is installed by
  1387 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1388 
  1389 * HOL/simplifier: terms of the form
  1390   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1391   are rewritten to
  1392   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1393   and those of the form
  1394   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1395   are rewritten to
  1396   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1397 
  1398 * HOL/datatype
  1399   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1400 
  1401   P(t_case f1 ... fn x) =
  1402      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1403         ...
  1404        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1405      )
  1406 
  1407   and a theorem `split_t_case_asm' of the form
  1408 
  1409   P(t_case f1 ... fn x) =
  1410     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1411         ...
  1412        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1413      )
  1414   which can be added to a simpset via `addsplits'. The existing theorems
  1415   expand_list_case and expand_option_case have been renamed to
  1416   split_list_case and split_option_case.
  1417 
  1418 * HOL/Arithmetic:
  1419   - `pred n' is automatically converted to `n-1'.
  1420     Users are strongly encouraged not to use `pred' any longer,
  1421     because it will disappear altogether at some point.
  1422   - Users are strongly encouraged to write "0 < n" rather than
  1423     "n ~= 0". Theorems and proof tools have been modified towards this
  1424     `standard'.
  1425 
  1426 * HOL/Lists:
  1427   the function "set_of_list" has been renamed "set" (and its theorems too);
  1428   the function "nth" now takes its arguments in the reverse order and
  1429   has acquired the infix notation "!" as in "xs!n".
  1430 
  1431 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1432 
  1433 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1434   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1435 
  1436 * HOL/record: extensible records with schematic structural subtyping
  1437 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1438 still lacks various theorems and concrete record syntax;
  1439 
  1440 
  1441 *** HOLCF ***
  1442 
  1443 * removed "axioms" and "generated by" sections;
  1444 
  1445 * replaced "ops" section by extended "consts" section, which is capable of
  1446   handling the continuous function space "->" directly;
  1447 
  1448 * domain package:
  1449   . proves theorems immediately and stores them in the theory,
  1450   . creates hierachical name space,
  1451   . now uses normal mixfix annotations (instead of cinfix...),
  1452   . minor changes to some names and values (for consistency),
  1453   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1454   . separator between mutual domain defs: changed "," to "and",
  1455   . improved handling of sort constraints;  now they have to
  1456     appear on the left-hand side of the equations only;
  1457 
  1458 * fixed LAM <x,y,zs>.b syntax;
  1459 
  1460 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1461 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1462 
  1463 
  1464 *** FOL and ZF ***
  1465 
  1466 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1467   with `addloop' of the simplifier to faciliate case splitting in premises.
  1468 
  1469 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1470 in HOL, they strip ALL and --> from proved theorems;
  1471 
  1472 
  1473 
  1474 New in Isabelle94-8 (May 1997)
  1475 ------------------------------
  1476 
  1477 *** General Changes ***
  1478 
  1479 * new utilities to build / run / maintain Isabelle etc. (in parts
  1480 still somewhat experimental); old Makefiles etc. still functional;
  1481 
  1482 * new 'Isabelle System Manual';
  1483 
  1484 * INSTALL text, together with ./configure and ./build scripts;
  1485 
  1486 * reimplemented type inference for greater efficiency, better error
  1487 messages and clean internal interface;
  1488 
  1489 * prlim command for dealing with lots of subgoals (an easier way of
  1490 setting goals_limit);
  1491 
  1492 
  1493 *** Syntax ***
  1494 
  1495 * supports alternative (named) syntax tables (parser and pretty
  1496 printer); internal interface is provided by add_modesyntax(_i);
  1497 
  1498 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1499 be used in conjunction with the Isabelle symbol font; uses the
  1500 "symbols" syntax table;
  1501 
  1502 * added token_translation interface (may translate name tokens in
  1503 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1504 the current print_mode); IMPORTANT: user print translation functions
  1505 are responsible for marking newly introduced bounds
  1506 (Syntax.mark_boundT);
  1507 
  1508 * token translations for modes "xterm" and "xterm_color" that display
  1509 names in bold, underline etc. or colors (which requires a color
  1510 version of xterm);
  1511 
  1512 * infixes may now be declared with names independent of their syntax;
  1513 
  1514 * added typed_print_translation (like print_translation, but may
  1515 access type of constant);
  1516 
  1517 
  1518 *** Classical Reasoner ***
  1519 
  1520 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  1521 some limitations.  Blast_tac...
  1522   + ignores addss, addbefore, addafter; this restriction is intrinsic
  1523   + ignores elimination rules that don't have the correct format
  1524         (the conclusion MUST be a formula variable)
  1525   + ignores types, which can make HOL proofs fail
  1526   + rules must not require higher-order unification, e.g. apply_type in ZF
  1527     [message "Function Var's argument not a bound variable" relates to this]
  1528   + its proof strategy is more general but can actually be slower
  1529 
  1530 * substitution with equality assumptions no longer permutes other
  1531 assumptions;
  1532 
  1533 * minor changes in semantics of addafter (now called addaltern); renamed
  1534 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  1535 (and access functions for it);
  1536 
  1537 * improved combination of classical reasoner and simplifier:
  1538   + functions for handling clasimpsets
  1539   + improvement of addss: now the simplifier is called _after_ the
  1540     safe steps.
  1541   + safe variant of addss called addSss: uses safe simplifications
  1542     _during_ the safe steps. It is more complete as it allows multiple
  1543     instantiations of unknowns (e.g. with slow_tac).
  1544 
  1545 *** Simplifier ***
  1546 
  1547 * added interface for simplification procedures (functions that
  1548 produce *proven* rewrite rules on the fly, depending on current
  1549 redex);
  1550 
  1551 * ordering on terms as parameter (used for ordered rewriting);
  1552 
  1553 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  1554 
  1555 * the solver is now split into a safe and an unsafe part.
  1556 This should be invisible for the normal user, except that the
  1557 functions setsolver and addsolver have been renamed to setSolver and
  1558 addSolver; added safe_asm_full_simp_tac;
  1559 
  1560 
  1561 *** HOL ***
  1562 
  1563 * a generic induction tactic `induct_tac' which works for all datatypes and
  1564 also for type `nat';
  1565 
  1566 * a generic case distinction tactic `exhaust_tac' which works for all
  1567 datatypes and also for type `nat';
  1568 
  1569 * each datatype comes with a function `size';
  1570 
  1571 * patterns in case expressions allow tuple patterns as arguments to
  1572 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1573 
  1574 * primrec now also works with type nat;
  1575 
  1576 * recdef: a new declaration form, allows general recursive functions to be
  1577 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1578 
  1579 * the constant for negation has been renamed from "not" to "Not" to
  1580 harmonize with FOL, ZF, LK, etc.;
  1581 
  1582 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1583 infinite lists;
  1584 
  1585 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1586 
  1587 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1588 problems in commutative rings, using axiomatic type classes for + and *;
  1589 
  1590 * more examples in HOL/MiniML and HOL/Auth;
  1591 
  1592 * more default rewrite rules for quantifiers, union/intersection;
  1593 
  1594 * a new constant `arbitrary == @x.False';
  1595 
  1596 * HOLCF/IOA replaces old HOL/IOA;
  1597 
  1598 * HOLCF changes: derived all rules and arities
  1599   + axiomatic type classes instead of classes
  1600   + typedef instead of faking type definitions
  1601   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1602   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1603   + eliminated the types void, one, tr
  1604   + use unit lift and bool lift (with translations) instead of one and tr
  1605   + eliminated blift from Lift3.thy (use Def instead of blift)
  1606   all eliminated rules are derived as theorems --> no visible changes ;
  1607 
  1608 
  1609 *** ZF ***
  1610 
  1611 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1612 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1613 as ZF_cs addSIs [equalityI];
  1614 
  1615 
  1616 
  1617 New in Isabelle94-7 (November 96)
  1618 ---------------------------------
  1619 
  1620 * allowing negative levels (as offsets) in prlev and choplev;
  1621 
  1622 * super-linear speedup for large simplifications;
  1623 
  1624 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1625 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1626 FAIL); can suppress it using the command Delsimps (ex_simps @
  1627 all_simps); De Morgan laws are also now included, by default;
  1628 
  1629 * improved printing of ==>  :  ~:
  1630 
  1631 * new object-logic "Sequents" adds linear logic, while replacing LK
  1632 and Modal (thanks to Sara Kalvala);
  1633 
  1634 * HOL/Auth: correctness proofs for authentication protocols;
  1635 
  1636 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1637 examples on HOL/Auth);
  1638 
  1639 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1640 the rewriter and classical reasoner simultaneously;
  1641 
  1642 * function uresult no longer returns theorems in "standard" format;
  1643 regain previous version by: val uresult = standard o uresult;
  1644 
  1645 
  1646 
  1647 New in Isabelle94-6
  1648 -------------------
  1649 
  1650 * oracles -- these establish an interface between Isabelle and trusted
  1651 external reasoners, which may deliver results as theorems;
  1652 
  1653 * proof objects (in particular record all uses of oracles);
  1654 
  1655 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1656 
  1657 * "constdefs" section in theory files;
  1658 
  1659 * "primrec" section (HOL) no longer requires names;
  1660 
  1661 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1662 
  1663 
  1664 
  1665 New in Isabelle94-5
  1666 -------------------
  1667 
  1668 * reduced space requirements;
  1669 
  1670 * automatic HTML generation from theories;
  1671 
  1672 * theory files no longer require "..." (quotes) around most types;
  1673 
  1674 * new examples, including two proofs of the Church-Rosser theorem;
  1675 
  1676 * non-curried (1994) version of HOL is no longer distributed;
  1677 
  1678 
  1679 
  1680 New in Isabelle94-4
  1681 -------------------
  1682 
  1683 * greatly reduced space requirements;
  1684 
  1685 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1686 
  1687 * searchable theorem database (see the section "Retrieving theorems" on
  1688 page 8 of the Reference Manual);
  1689 
  1690 * new examples, including Grabczewski's monumental case study of the
  1691 Axiom of Choice;
  1692 
  1693 * The previous version of HOL renamed to Old_HOL;
  1694 
  1695 * The new version of HOL (previously called CHOL) uses a curried syntax
  1696 for functions.  Application looks like f a b instead of f(a,b);
  1697 
  1698 * Mutually recursive inductive definitions finally work in HOL;
  1699 
  1700 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1701 translates to the operator "split";
  1702 
  1703 
  1704 
  1705 New in Isabelle94-3
  1706 -------------------
  1707 
  1708 * new infix operator, addss, allowing the classical reasoner to
  1709 perform simplification at each step of its search.  Example:
  1710         fast_tac (cs addss ss)
  1711 
  1712 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1713 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1714 look like (a,b) instead of <a,b>;
  1715 
  1716 * PLEASE NOTE: CHOL will eventually replace HOL!
  1717 
  1718 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1719 It translates to the operator "split".  A new theory of integers is available;
  1720 
  1721 * In ZF, integer numerals now denote two's-complement binary integers.
  1722 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1723 
  1724 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1725 of the Axiom of Choice;
  1726 
  1727 
  1728 
  1729 New in Isabelle94-2
  1730 -------------------
  1731 
  1732 * Significantly faster resolution;
  1733 
  1734 * the different sections in a .thy file can now be mixed and repeated
  1735 freely;
  1736 
  1737 * Database of theorems for FOL, HOL and ZF.  New
  1738 commands including qed, qed_goal and bind_thm store theorems in the database.
  1739 
  1740 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1741 a given theory (thms_of), or find out what theory a theorem was proved in
  1742 (theory_of_thm);
  1743 
  1744 * Bugs fixed in the inductive definition and datatype packages;
  1745 
  1746 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1747 and HOL_dup_cs obsolete;
  1748 
  1749 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1750 have been removed;
  1751 
  1752 * Simpler definition of function space in ZF;
  1753 
  1754 * new results about cardinal and ordinal arithmetic in ZF;
  1755 
  1756 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1757 types;
  1758 
  1759 
  1760 $Id$