NEWS
author paulson
Mon Apr 09 10:10:21 2001 +0200 (2001-04-09)
changeset 11241 61b21aacf04a
parent 11181 d04f57b91166
child 11307 891fbd3f4881
permissions -rw-r--r--
Isar hint
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 * Classical reasoner: renamed addaltern to addafter, addSaltern to addSafter
     5 
     6 * HOL: added safe wrapper "split_conv_tac" to claset. EXISTING PROOFS MAY FAIL
     7 
     8 * HOL: made split_all_tac safe. EXISTING PROOFS MAY FAIL OR LOOP, so in this
     9   (rare) case use   delSWrapper "split_all_tac" addSbefore 
    10                     ("unsafe_split_all_tac", unsafe_split_all_tac)
    11 
    12 
    13 New in Isabelle99-2 (February 2001)
    14 -----------------------------------
    15 
    16 *** Overview of INCOMPATIBILITIES ***
    17 
    18 * HOL: please note that theories in the Library and elsewhere often use the
    19 new-style (Isar) format; to refer to their theorems in an ML script you must
    20 bind them to ML identifers by e.g.	val thm_name = thm "thm_name";
    21 
    22 * HOL: inductive package no longer splits induction rule aggressively,
    23 but only as far as specified by the introductions given; the old
    24 format may be recovered via ML function complete_split_rule or attribute
    25 'split_rule (complete)';
    26 
    27 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
    28 gfp_Tarski to gfp_unfold;
    29 
    30 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
    31 
    32 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
    33 relation); infix "^^" has been renamed "``"; infix "``" has been
    34 renamed "`"; "univalent" has been renamed "single_valued";
    35 
    36 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
    37 operation;
    38 
    39 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
    40 
    41 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
    42 
    43 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
    44 consequence, it is no longer monotonic wrt. the local goal context
    45 (which is now passed through the inductive cases);
    46 
    47 * Document preparation: renamed standard symbols \<ll> to \<lless> and
    48 \<gg> to \<ggreater>;
    49 
    50 
    51 *** Document preparation ***
    52 
    53 * \isabellestyle{NAME} selects version of Isabelle output (currently
    54 available: are "it" for near math-mode best-style output, "sl" for
    55 slanted text style, and "tt" for plain type-writer; if no
    56 \isabellestyle command is given, output is according to slanted
    57 type-writer);
    58 
    59 * support sub/super scripts (for single symbols only), input syntax is
    60 like this: "A\<^sup>*" or "A\<^sup>\<star>";
    61 
    62 * some more standard symbols; see Appendix A of the system manual for
    63 the complete list of symbols defined in isabellesym.sty;
    64 
    65 * improved isabelle style files; more abstract symbol implementation
    66 (should now use \isamath{...} and \isatext{...} in custom symbol
    67 definitions);
    68 
    69 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
    70 state; Note that presentation of goal states does not conform to
    71 actual human-readable proof documents.  Please do not include goal
    72 states into document output unless you really know what you are doing!
    73 
    74 * proper indentation of antiquoted output with proportional LaTeX
    75 fonts;
    76 
    77 * no_document ML operator temporarily disables LaTeX document
    78 generation;
    79 
    80 * isatool unsymbolize tunes sources for plain ASCII communication;
    81 
    82 
    83 *** Isar ***
    84 
    85 * Pure: Isar now suffers initial goal statements to contain unbound
    86 schematic variables (this does not conform to actual readable proof
    87 documents, due to unpredictable outcome and non-compositional proof
    88 checking); users who know what they are doing may use schematic goals
    89 for Prolog-style synthesis of proven results;
    90 
    91 * Pure: assumption method (an implicit finishing) now handles actual
    92 rules as well;
    93 
    94 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
    95 initial goal, declare "that" only as Pure intro (only for single
    96 steps); the "that" rule assumption may now be involved in implicit
    97 finishing, thus ".." becomes a feasible for trivial obtains;
    98 
    99 * Pure: default proof step now includes 'intro_classes'; thus trivial
   100 instance proofs may be performed by "..";
   101 
   102 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   103 statements as well;
   104 
   105 * Pure: more robust selection of calculational rules;
   106 
   107 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   108 rule (as well as the assumption rule);
   109 
   110 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   111 lemmas, using the graph browser tool;
   112 
   113 * Pure: predict failure of "show" in interactive mode;
   114 
   115 * Pure: 'thms_containing' now takes actual terms as arguments;
   116 
   117 * HOL: improved method 'induct' --- now handles non-atomic goals
   118 (potential INCOMPATIBILITY); tuned error handling;
   119 
   120 * HOL: cases and induct rules now provide explicit hints about the
   121 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   122 any remaining facts are inserted into the goal verbatim;
   123 
   124 * HOL: local contexts (aka cases) may now contain term bindings as
   125 well; the 'cases' and 'induct' methods new provide a ?case binding for
   126 the result to be shown in each case;
   127 
   128 * HOL: added 'recdef_tc' command;
   129 
   130 * isatool convert assists in eliminating legacy ML scripts;
   131 
   132 
   133 *** HOL ***
   134 
   135 * HOL/Library: a collection of generic theories to be used together
   136 with main HOL; the theory loader path already includes this directory
   137 by default; the following existing theories have been moved here:
   138 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   139 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   140 
   141 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   142 modelling and verification task performed in Isabelle/HOL +
   143 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   144 
   145 * HOL/Algebra: special summation operator SUM no longer exists, it has
   146 been replaced by setsum; infix 'assoc' now has priority 50 (like
   147 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   148 'domain', this makes the theory consistent with mathematical
   149 literature;
   150 
   151 * HOL basics: added overloaded operations "inverse" and "divide"
   152 (infix "/"), syntax for generic "abs" operation, generic summation
   153 operator \<Sum>;
   154 
   155 * HOL/typedef: simplified package, provide more useful rules (see also
   156 HOL/subset.thy);
   157 
   158 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   159 now expressed as a proper nested rule (old-style tactic scripts may
   160 require atomize_strip_tac to cope with non-atomic premises);
   161 
   162 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   163 to "split_conv" (old name still available for compatibility);
   164 
   165 * HOL: improved concrete syntax for strings (e.g. allows translation
   166 rules with string literals);
   167 
   168 * HOL-Hyperreal: a new target, extending HOL-Real with the hyperreals
   169 and Fleuriot's mechanization of analysis;
   170 
   171 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   172 
   173 
   174 *** CTT ***
   175 
   176 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   177 "lam" is displayed as TWO lambda-symbols
   178 
   179 * CTT: theory Main now available, containing everything (that is, Bool
   180 and Arith);
   181 
   182 
   183 *** General ***
   184 
   185 * Pure: the Simplifier has been implemented properly as a derived rule
   186 outside of the actual kernel (at last!); the overall performance
   187 penalty in practical applications is about 50%, while reliability of
   188 the Isabelle inference kernel has been greatly improved;
   189 
   190 * print modes "brackets" and "no_brackets" control output of nested =>
   191 (types) and ==> (props); the default behaviour is "brackets";
   192 
   193 * Provers: fast_tac (and friends) now handle actual object-logic rules
   194 as assumptions as well;
   195 
   196 * system: support Poly/ML 4.0;
   197 
   198 * system: isatool install handles KDE version 1 or 2;
   199 
   200 
   201 
   202 New in Isabelle99-1 (October 2000)
   203 ----------------------------------
   204 
   205 *** Overview of INCOMPATIBILITIES ***
   206 
   207 * HOL: simplification of natural numbers is much changed; to partly
   208 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   209 issue the following ML commands:
   210 
   211   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   212   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   213 
   214 * HOL: simplification no longer dives into case-expressions; this is
   215 controlled by "t.weak_case_cong" for each datatype t;
   216 
   217 * HOL: nat_less_induct renamed to less_induct;
   218 
   219 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   220 fixsome to patch .thy and .ML sources automatically;
   221 
   222   select_equality  -> some_equality
   223   select_eq_Ex     -> some_eq_ex
   224   selectI2EX       -> someI2_ex
   225   selectI2         -> someI2
   226   selectI          -> someI
   227   select1_equality -> some1_equality
   228   Eps_sym_eq       -> some_sym_eq_trivial
   229   Eps_eq           -> some_eq_trivial
   230 
   231 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   232 
   233 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   234 instead);
   235 
   236 * HOL: the recursion equations generated by 'recdef' are now called
   237 f.simps instead of f.rules;
   238 
   239 * HOL: qed_spec_mp now also handles bounded ALL as well;
   240 
   241 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   242 sometimes be needed;
   243 
   244 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   245 
   246 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   247 
   248 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   249 product is now "<*>" instead of "Times"; the lexicographic product is
   250 now "<*lex*>" instead of "**";
   251 
   252 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   253 of main HOL, but was unused); better use HOL's datatype package;
   254 
   255 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   256 the old syntax may be recovered as follows:
   257 
   258   syntax (symbols)
   259     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   260       (infixl "\\<oplus>" 100)
   261 
   262 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   263 
   264 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   265 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   266 internally;
   267 
   268 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   269 changed from A/r to A//r;
   270 
   271 * ZF: new treatment of arithmetic (nat & int) may break some old
   272 proofs;
   273 
   274 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   275 rulify -> rule_format, elimify -> elim_format, ...);
   276 
   277 * Isar/Provers: intro/elim/dest attributes changed; renamed
   278 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   279 should have to change intro!! to intro? only); replaced "delrule" by
   280 "rule del";
   281 
   282 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   283 
   284 * Provers: strengthened force_tac by using new first_best_tac;
   285 
   286 * LaTeX document preparation: several changes of isabelle.sty (see
   287 lib/texinputs);
   288 
   289 
   290 *** Document preparation ***
   291 
   292 * formal comments (text blocks etc.) in new-style theories may now
   293 contain antiquotations of thm/prop/term/typ/text to be presented
   294 according to latex print mode; concrete syntax is like this:
   295 @{term[show_types] "f(x) = a + x"};
   296 
   297 * isatool mkdir provides easy setup of Isabelle session directories,
   298 including proper document sources;
   299 
   300 * generated LaTeX sources are now deleted after successful run
   301 (isatool document -c); may retain a copy somewhere else via -D option
   302 of isatool usedir;
   303 
   304 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   305 style files, achieving self-contained LaTeX sources and simplifying
   306 LaTeX debugging;
   307 
   308 * old-style theories now produce (crude) LaTeX output as well;
   309 
   310 * browser info session directories are now self-contained (may be put
   311 on WWW server seperately); improved graphs of nested sessions; removed
   312 graph for 'all sessions';
   313 
   314 * several improvements in isabelle style files; \isabellestyle{it}
   315 produces fake math mode output; \isamarkupheader is now \section by
   316 default; see lib/texinputs/isabelle.sty etc.;
   317 
   318 
   319 *** Isar ***
   320 
   321 * Isar/Pure: local results and corresponding term bindings are now
   322 subject to Hindley-Milner polymorphism (similar to ML); this
   323 accommodates incremental type-inference very nicely;
   324 
   325 * Isar/Pure: new derived language element 'obtain' supports
   326 generalized existence reasoning;
   327 
   328 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   329 support accumulation of results, without applying any rules yet;
   330 useful to collect intermediate results without explicit name
   331 references, and for use with transitivity rules with more than 2
   332 premises;
   333 
   334 * Isar/Pure: scalable support for case-analysis type proofs: new
   335 'case' language element refers to local contexts symbolically, as
   336 produced by certain proof methods; internally, case names are attached
   337 to theorems as "tags";
   338 
   339 * Isar/Pure: theory command 'hide' removes declarations from
   340 class/type/const name spaces;
   341 
   342 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   343 indicate potential overloading;
   344 
   345 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   346 
   347 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   348 "{a,b,c}" instead of {a,b,c};
   349 
   350 * Isar/Pure now provides its own version of intro/elim/dest
   351 attributes; useful for building new logics, but beware of confusion
   352 with the version in Provers/classical;
   353 
   354 * Isar/Pure: the local context of (non-atomic) goals is provided via
   355 case name 'antecedent';
   356 
   357 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   358 to the current context is now done automatically);
   359 
   360 * Isar/Pure: theory command 'method_setup' provides a simple interface
   361 for definining proof methods in ML;
   362 
   363 * Isar/Provers: intro/elim/dest attributes changed; renamed
   364 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   365 most cases, one should have to change intro!! to intro? only);
   366 replaced "delrule" by "rule del";
   367 
   368 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   369 'symmetric' attribute (the latter supercedes [RS sym]);
   370 
   371 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   372 method modifier); 'simp' method: 'only:' modifier removes loopers as
   373 well (including splits);
   374 
   375 * Isar/Provers: Simplifier and Classical methods now support all kind
   376 of modifiers used in the past, including 'cong', 'iff', etc.
   377 
   378 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   379 of Simplifier and Classical reasoner);
   380 
   381 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   382 now support named cases; major packages (inductive, datatype, primrec,
   383 recdef) support case names and properly name parameters;
   384 
   385 * Isar/HOL: new transitivity rules for substitution in inequalities --
   386 monotonicity conditions are extracted to be proven at end of
   387 calculations;
   388 
   389 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   390 method anyway;
   391 
   392 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   393 split_if split_if_asm; datatype package provides theorems foo.splits =
   394 foo.split foo.split_asm for each datatype;
   395 
   396 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   397 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   398 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   399 use "(cases (simplified))" method in proper proof texts);
   400 
   401 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   402 
   403 * Isar: names of theorems etc. may be natural numbers as well;
   404 
   405 * Isar: 'pr' command: optional arguments for goals_limit and
   406 ProofContext.prems_limit; no longer prints theory contexts, but only
   407 proof states;
   408 
   409 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   410 additional print modes to be specified; e.g. "pr(latex)" will print
   411 proof state according to the Isabelle LaTeX style;
   412 
   413 * Isar: improved support for emulating tactic scripts, including proof
   414 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   415 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   416 (for HOL datatypes);
   417 
   418 * Isar: simplified (more robust) goal selection of proof methods: 1st
   419 goal, all goals, or explicit goal specifier (tactic emulation); thus
   420 'proof method scripts' have to be in depth-first order;
   421 
   422 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   423 
   424 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   425 should instead use individual commands for printing items
   426 (print_commands, print_methods etc.);
   427 
   428 * Isar: added 'nothing' --- the empty list of theorems;
   429 
   430 
   431 *** HOL ***
   432 
   433 * HOL/MicroJava: formalization of a fragment of Java, together with a
   434 corresponding virtual machine and a specification of its bytecode
   435 verifier and a lightweight bytecode verifier, including proofs of
   436 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   437 Cornelia Pusch (see also the homepage of project Bali at
   438 http://isabelle.in.tum.de/Bali/);
   439 
   440 * HOL/Algebra: new theory of rings and univariate polynomials, by
   441 Clemens Ballarin;
   442 
   443 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   444 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   445 Rasmussen;
   446 
   447 * HOL/Lattice: fundamental concepts of lattice theory and order
   448 structures, including duals, properties of bounds versus algebraic
   449 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   450 Theorem for complete lattices etc.; may also serve as a demonstration
   451 for abstract algebraic reasoning using axiomatic type classes, and
   452 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   453 
   454 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   455 von Oheimb;
   456 
   457 * HOL/IMPP: extension of IMP with local variables and mutually
   458 recursive procedures, by David von Oheimb;
   459 
   460 * HOL/Lambda: converted into new-style theory and document;
   461 
   462 * HOL/ex/Multiquote: example of multiple nested quotations and
   463 anti-quotations -- basically a generalized version of de-Bruijn
   464 representation; very useful in avoiding lifting of operations;
   465 
   466 * HOL/record: added general record equality rule to simpset; fixed
   467 select-update simplification procedure to handle extended records as
   468 well; admit "r" as field name;
   469 
   470 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   471 other numeric types and also as the identity of groups, rings, etc.;
   472 
   473 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   474 Types nat and int belong to this axclass;
   475 
   476 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   477    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   478    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   479   two terms #m*u and #n*u are replaced by #(m+n)*u
   480     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   481   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   482     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   483 
   484 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   485 powerful prover for predicate logic but knows nothing of clasets; see
   486 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   487 
   488 * HOL: new version of "case_tac" subsumes both boolean case split and
   489 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   490 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   491 
   492 * HOL: simplification no longer dives into case-expressions: only the
   493 selector expression is simplified, but not the remaining arms; to
   494 enable full simplification of case-expressions for datatype t, you may
   495 remove t.weak_case_cong from the simpset, either globally (Delcongs
   496 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   497 
   498 * HOL/recdef: the recursion equations generated by 'recdef' for
   499 function 'f' are now called f.simps instead of f.rules; if all
   500 termination conditions are proved automatically, these simplification
   501 rules are added to the simpset, as in primrec; rules may be named
   502 individually as well, resulting in a separate list of theorems for
   503 each equation;
   504 
   505 * HOL/While is a new theory that provides a while-combinator. It
   506 permits the definition of tail-recursive functions without the
   507 provision of a termination measure. The latter is necessary once the
   508 invariant proof rule for while is applied.
   509 
   510 * HOL: new (overloaded) notation for the set of elements below/above
   511 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   512 
   513 * HOL: theorems impI, allI, ballI bound as "strip";
   514 
   515 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   516 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   517 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   518 
   519 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   520 
   521 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   522 main HOL, but was unused);
   523 
   524 * HOL: fewer consts declared as global (e.g. have to refer to
   525 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   526 
   527 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   528 in case of overlap with user translations (e.g. judgements over
   529 tuples); (note that the underlying logical represenation is still
   530 bogus);
   531 
   532 
   533 *** ZF ***
   534 
   535 * ZF: simplification automatically cancels common terms in arithmetic
   536 expressions over nat and int;
   537 
   538 * ZF: new treatment of nat to minimize type-checking: all operators
   539 coerce their operands to a natural number using the function natify,
   540 making the algebraic laws unconditional;
   541 
   542 * ZF: as above, for int: operators coerce their operands to an integer
   543 using the function intify;
   544 
   545 * ZF: the integer library now contains many of the usual laws for the
   546 orderings, including $<=, and monotonicity laws for $+ and $*;
   547 
   548 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
   549 simplification;
   550 
   551 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
   552 to the simplifier and classical reasoner simultaneously;
   553 
   554 
   555 *** General ***
   556 
   557 * Provers: blast_tac now handles actual object-logic rules as
   558 assumptions; note that auto_tac uses blast_tac internally as well;
   559 
   560 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
   561 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
   562 
   563 * Provers: delrules now handles destruct rules as well (no longer need
   564 explicit make_elim);
   565 
   566 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
   567   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   568 use instead the strong form,
   569   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   570 in HOL, FOL and ZF the function cla_make_elim will create such rules
   571 from destruct-rules;
   572 
   573 * Provers: Simplifier.easy_setup provides a fast path to basic
   574 Simplifier setup for new object-logics;
   575 
   576 * Pure: AST translation rules no longer require constant head on LHS;
   577 
   578 * Pure: improved name spaces: ambiguous output is qualified; support
   579 for hiding of names;
   580 
   581 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
   582 XSYMBOL_HOME; no longer need to do manual configuration in most
   583 situations;
   584 
   585 * system: compression of ML heaps images may now be controlled via -c
   586 option of isabelle and isatool usedir (currently only observed by
   587 Poly/ML);
   588 
   589 * system: isatool installfonts may handle X-Symbol fonts as well (very
   590 useful for remote X11);
   591 
   592 * system: provide TAGS file for Isabelle sources;
   593 
   594 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
   595 order;
   596 
   597 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
   598 timing flag supersedes proof_timing and Toplevel.trace;
   599 
   600 * ML: new combinators |>> and |>>> for incremental transformations
   601 with secondary results (e.g. certain theory extensions):
   602 
   603 * ML: PureThy.add_defs gets additional argument to indicate potential
   604 overloading (usually false);
   605 
   606 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
   607 results;
   608 
   609 
   610 
   611 New in Isabelle99 (October 1999)
   612 --------------------------------
   613 
   614 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   615 
   616 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
   617 are no longer simplified.  (This allows the simplifier to unfold recursive
   618 functional programs.)  To restore the old behaviour, declare
   619 
   620     Delcongs [if_weak_cong];
   621 
   622 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
   623 complement;
   624 
   625 * HOL: the predicate "inj" is now defined by translation to "inj_on";
   626 
   627 * HOL/datatype: mutual_induct_tac no longer exists --
   628   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
   629 
   630 * HOL/typedef: fixed type inference for representing set; type
   631 arguments now have to occur explicitly on the rhs as type constraints;
   632 
   633 * ZF: The con_defs part of an inductive definition may no longer refer
   634 to constants declared in the same theory;
   635 
   636 * HOL, ZF: the function mk_cases, generated by the inductive
   637 definition package, has lost an argument.  To simplify its result, it
   638 uses the default simpset instead of a supplied list of theorems.
   639 
   640 * HOL/List: the constructors of type list are now Nil and Cons;
   641 
   642 * Simplifier: the type of the infix ML functions
   643         setSSolver addSSolver setSolver addSolver
   644 is now  simpset * solver -> simpset  where `solver' is a new abstract type
   645 for packaging solvers. A solver is created via
   646         mk_solver: string -> (thm list -> int -> tactic) -> solver
   647 where the string argument is only a comment.
   648 
   649 
   650 *** Proof tools ***
   651 
   652 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
   653 decision procedure for linear arithmetic. Currently it is used for
   654 types `nat', `int', and `real' in HOL (see below); it can, should and
   655 will be instantiated for other types and logics as well.
   656 
   657 * The simplifier now accepts rewrite rules with flexible heads, eg
   658      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
   659   They are applied like any rule with a non-pattern lhs, i.e. by first-order
   660   matching.
   661 
   662 
   663 *** General ***
   664 
   665 * New Isabelle/Isar subsystem provides an alternative to traditional
   666 tactical theorem proving; together with the ProofGeneral/isar user
   667 interface it offers an interactive environment for developing human
   668 readable proof documents (Isar == Intelligible semi-automated
   669 reasoning); for further information see isatool doc isar-ref,
   670 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
   671 
   672 * improved and simplified presentation of theories: better HTML markup
   673 (including colors), graph views in several sizes; isatool usedir now
   674 provides a proper interface for user theories (via -P option); actual
   675 document preparation based on (PDF)LaTeX is available as well (for
   676 new-style theories only); see isatool doc system for more information;
   677 
   678 * native support for Proof General, both for classic Isabelle and
   679 Isabelle/Isar;
   680 
   681 * ML function thm_deps visualizes dependencies of theorems and lemmas,
   682 using the graph browser tool;
   683 
   684 * Isabelle manuals now also available as PDF;
   685 
   686 * theory loader rewritten from scratch (may not be fully
   687 bug-compatible); old loadpath variable has been replaced by show_path,
   688 add_path, del_path, reset_path functions; new operations such as
   689 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
   690 isatool doc ref);
   691 
   692 * improved isatool install: option -k creates KDE application icon,
   693 option -p DIR installs standalone binaries;
   694 
   695 * added ML_PLATFORM setting (useful for cross-platform installations);
   696 more robust handling of platform specific ML images for SML/NJ;
   697 
   698 * the settings environment is now statically scoped, i.e. it is never
   699 created again in sub-processes invoked from isabelle, isatool, or
   700 Isabelle;
   701 
   702 * path element specification '~~' refers to '$ISABELLE_HOME';
   703 
   704 * in locales, the "assumes" and "defines" parts may be omitted if
   705 empty;
   706 
   707 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   708 long arrows);
   709 
   710 * new print_mode "HTML";
   711 
   712 * new flag show_tags controls display of tags of theorems (which are
   713 basically just comments that may be attached by some tools);
   714 
   715 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   716 mode and goal output format:
   717 
   718 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   719 244c244
   720 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   721 ---
   722 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   723 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   724 181c181
   725 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   726 ---
   727 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   728 
   729 * function bind_thms stores lists of theorems (cf. bind_thm);
   730 
   731 * new shorthand tactics ftac, eatac, datac, fatac;
   732 
   733 * qed (and friends) now accept "" as result name; in that case the
   734 theorem is not stored, but proper checks and presentation of the
   735 result still apply;
   736 
   737 * theorem database now also indexes constants "Trueprop", "all",
   738 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   739 
   740 
   741 *** HOL ***
   742 
   743 ** HOL arithmetic **
   744 
   745 * There are now decision procedures for linear arithmetic over nat and
   746 int:
   747 
   748 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   749 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   750 are treated as atomic; subformulae not involving type `nat' or `int'
   751 are ignored; quantified subformulae are ignored unless they are
   752 positive universal or negative existential. The tactic has to be
   753 invoked by hand and can be a little bit slow. In particular, the
   754 running time is exponential in the number of occurrences of `min' and
   755 `max', and `-' on `nat'.
   756 
   757 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   758 (negated) (in)equalities among the premises and the conclusion into
   759 account (i.e. no compound formulae) and does not know about `min' and
   760 `max', and `-' on `nat'. It is fast and is used automatically by the
   761 simplifier.
   762 
   763 NB: At the moment, these decision procedures do not cope with mixed
   764 nat/int formulae where the two parts interact, such as `m < n ==>
   765 int(m) < int(n)'.
   766 
   767 * HOL/Numeral provides a generic theory of numerals (encoded
   768 efficiently as bit strings); setup for types nat/int/real is in place;
   769 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   770 int, existing theories and proof scripts may require a few additional
   771 type constraints;
   772 
   773 * integer division and remainder can now be performed on constant
   774 arguments;
   775 
   776 * many properties of integer multiplication, division and remainder
   777 are now available;
   778 
   779 * An interface to the Stanford Validity Checker (SVC) is available through the
   780 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   781 are proved automatically.  SVC must be installed separately, and its results
   782 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   783 invocation of the underlying oracle).  For SVC see
   784   http://verify.stanford.edu/SVC
   785 
   786 * IsaMakefile: the HOL-Real target now builds an actual image;
   787 
   788 
   789 ** HOL misc **
   790 
   791 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   792 (in Isabelle/Isar) -- by Gertrud Bauer;
   793 
   794 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   795 analysis for assembly languages with subtypes;
   796 
   797 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   798 -- avoids syntactic ambiguities and treats state, transition, and
   799 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   800 changed syntax and (many) tactics;
   801 
   802 * HOL/inductive: Now also handles more general introduction rules such
   803   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
   804   theorems are now maintained within the theory (maintained via the
   805   "mono" attribute);
   806 
   807 * HOL/datatype: Now also handles arbitrarily branching datatypes
   808   (using function types) such as
   809 
   810   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
   811 
   812 * HOL/record: record_simproc (part of the default simpset) takes care
   813 of selectors applied to updated records; record_split_tac is no longer
   814 part of the default claset; update_defs may now be removed from the
   815 simpset in many cases; COMPATIBILITY: old behavior achieved by
   816 
   817   claset_ref () := claset() addSWrapper record_split_wrapper;
   818   Delsimprocs [record_simproc]
   819 
   820 * HOL/typedef: fixed type inference for representing set; type
   821 arguments now have to occur explicitly on the rhs as type constraints;
   822 
   823 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
   824 names rather than an ML expression;
   825 
   826 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
   827 supplied later.  Program schemes can be defined, such as
   828     "While B C s = (if B s then While B C (C s) else s)"
   829 where the well-founded relation can be chosen after B and C have been given.
   830 
   831 * HOL/List: the constructors of type list are now Nil and Cons;
   832 INCOMPATIBILITY: while [] and infix # syntax is still there, of
   833 course, ML tools referring to List.list.op # etc. have to be adapted;
   834 
   835 * HOL_quantifiers flag superseded by "HOL" print mode, which is
   836 disabled by default; run isabelle with option -m HOL to get back to
   837 the original Gordon/HOL-style output;
   838 
   839 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
   840 ALL x<=y. P, EX x<y. P, EX x<=y. P;
   841 
   842 * HOL basic syntax simplified (more orthogonal): all variants of
   843 All/Ex now support plain / symbolic / HOL notation; plain syntax for
   844 Eps operator is provided as well: "SOME x. P[x]";
   845 
   846 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
   847 
   848 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
   849 thus available for user theories;
   850 
   851 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
   852 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
   853 time;
   854 
   855 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
   856 several times and then mp;
   857 
   858 
   859 *** LK ***
   860 
   861 * the notation <<...>> is now available as a notation for sequences of
   862 formulas;
   863 
   864 * the simplifier is now installed
   865 
   866 * the axiom system has been generalized (thanks to Soren Heilmann)
   867 
   868 * the classical reasoner now has a default rule database
   869 
   870 
   871 *** ZF ***
   872 
   873 * new primrec section allows primitive recursive functions to be given
   874 directly (as in HOL) over datatypes and the natural numbers;
   875 
   876 * new tactics induct_tac and exhaust_tac for induction (or case
   877 analysis) over datatypes and the natural numbers;
   878 
   879 * the datatype declaration of type T now defines the recursor T_rec;
   880 
   881 * simplification automatically does freeness reasoning for datatype
   882 constructors;
   883 
   884 * automatic type-inference, with AddTCs command to insert new
   885 type-checking rules;
   886 
   887 * datatype introduction rules are now added as Safe Introduction rules
   888 to the claset;
   889 
   890 * the syntax "if P then x else y" is now available in addition to
   891 if(P,x,y);
   892 
   893 
   894 *** Internal programming interfaces ***
   895 
   896 * tuned simplifier trace output; new flag debug_simp;
   897 
   898 * structures Vartab / Termtab (instances of TableFun) offer efficient
   899 tables indexed by indexname_ord / term_ord (compatible with aconv);
   900 
   901 * AxClass.axclass_tac lost the theory argument;
   902 
   903 * tuned current_goals_markers semantics: begin / end goal avoids
   904 printing empty lines;
   905 
   906 * removed prs and prs_fn hook, which was broken because it did not
   907 include \n in its semantics, forcing writeln to add one
   908 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
   909 string -> unit if you really want to output text without newline;
   910 
   911 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
   912 plain output, interface builders may have to enable 'isabelle_font'
   913 mode to get Isabelle font glyphs as before;
   914 
   915 * refined token_translation interface; INCOMPATIBILITY: output length
   916 now of type real instead of int;
   917 
   918 * theory loader actions may be traced via new ThyInfo.add_hook
   919 interface (see src/Pure/Thy/thy_info.ML); example application: keep
   920 your own database of information attached to *whole* theories -- as
   921 opposed to intra-theory data slots offered via TheoryDataFun;
   922 
   923 * proper handling of dangling sort hypotheses (at last!);
   924 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
   925 extra sort hypotheses that can be witnessed from the type signature;
   926 the force_strip_shyps flag is gone, any remaining shyps are simply
   927 left in the theorem (with a warning issued by strip_shyps_warning);
   928 
   929 
   930 
   931 New in Isabelle98-1 (October 1998)
   932 ----------------------------------
   933 
   934 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   935 
   936 * several changes of automated proof tools;
   937 
   938 * HOL: major changes to the inductive and datatype packages, including
   939 some minor incompatibilities of theory syntax;
   940 
   941 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
   942 called `inj_on';
   943 
   944 * HOL: removed duplicate thms in Arith:
   945   less_imp_add_less  should be replaced by  trans_less_add1
   946   le_imp_add_le      should be replaced by  trans_le_add1
   947 
   948 * HOL: unary minus is now overloaded (new type constraints may be
   949 required);
   950 
   951 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
   952 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
   953 now taken as an integer constant.
   954 
   955 * Pure: ML function 'theory_of' renamed to 'theory';
   956 
   957 
   958 *** Proof tools ***
   959 
   960 * Simplifier:
   961   1. Asm_full_simp_tac is now more aggressive.
   962      1. It will sometimes reorient premises if that increases their power to
   963         simplify.
   964      2. It does no longer proceed strictly from left to right but may also
   965         rotate premises to achieve further simplification.
   966      For compatibility reasons there is now Asm_lr_simp_tac which is like the
   967      old Asm_full_simp_tac in that it does not rotate premises.
   968   2. The simplifier now knows a little bit about nat-arithmetic.
   969 
   970 * Classical reasoner: wrapper mechanism for the classical reasoner now
   971 allows for selected deletion of wrappers, by introduction of names for
   972 wrapper functionals.  This implies that addbefore, addSbefore,
   973 addaltern, and addSaltern now take a pair (name, tactic) as argument,
   974 and that adding two tactics with the same name overwrites the first
   975 one (emitting a warning).
   976   type wrapper = (int -> tactic) -> (int -> tactic)
   977   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
   978   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
   979   delWrapper, delSWrapper: claset *  string            -> claset
   980   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
   981 
   982 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
   983 semantics; addbefore now affects only the unsafe part of step_tac
   984 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
   985 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
   986 by Force_tac;
   987 
   988 * Classical reasoner: setwrapper to setWrapper and compwrapper to
   989 compWrapper; added safe wrapper (and access functions for it);
   990 
   991 * HOL/split_all_tac is now much faster and fails if there is nothing
   992 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
   993 and the names of the automatically generated variables have changed.
   994 split_all_tac has moved within claset() from unsafe wrappers to safe
   995 wrappers, which means that !!-bound variables are split much more
   996 aggressively, and safe_tac and clarify_tac now split such variables.
   997 If this splitting is not appropriate, use delSWrapper "split_all_tac".
   998 Note: the same holds for record_split_tac, which does the job of
   999 split_all_tac for record fields.
  1000 
  1001 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1002 permanently to the default simpset using Addsplits just like
  1003 Addsimps. They can be removed via Delsplits just like
  1004 Delsimps. Lower-case versions are also available.
  1005 
  1006 * HOL/Simplifier: The rule split_if is now part of the default
  1007 simpset. This means that the simplifier will eliminate all occurrences
  1008 of if-then-else in the conclusion of a goal. To prevent this, you can
  1009 either remove split_if completely from the default simpset by
  1010 `Delsplits [split_if]' or remove it in a specific call of the
  1011 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1012 other case splitting rules to/from the default simpset: every datatype
  1013 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1014 t is the name of the datatype).
  1015 
  1016 * Classical reasoner / Simplifier combination: new force_tac (and
  1017 derivatives Force_tac, force) combines rewriting and classical
  1018 reasoning (and whatever other tools) similarly to auto_tac, but is
  1019 aimed to solve the given subgoal completely.
  1020 
  1021 
  1022 *** General ***
  1023 
  1024 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1025 and `goalw': the theory is no longer needed as an explicit argument -
  1026 the current theory context is used; assumptions are no longer returned
  1027 at the ML-level unless one of them starts with ==> or !!; it is
  1028 recommended to convert to these new commands using isatool fixgoal
  1029 (backup your sources first!);
  1030 
  1031 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1032 the current theory context, and 'theory' to lookup stored theories;
  1033 
  1034 * new theory section 'locale' for declaring constants, assumptions and
  1035 definitions that have local scope;
  1036 
  1037 * new theory section 'nonterminals' for purely syntactic types;
  1038 
  1039 * new theory section 'setup' for generic ML setup functions
  1040 (e.g. package initialization);
  1041 
  1042 * the distribution now includes Isabelle icons: see
  1043 lib/logo/isabelle-{small,tiny}.xpm;
  1044 
  1045 * isatool install - install binaries with absolute references to
  1046 ISABELLE_HOME/bin;
  1047 
  1048 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1049 
  1050 * print mode 'emacs' reserved for Isamode;
  1051 
  1052 * support multiple print (ast) translations per constant name;
  1053 
  1054 * theorems involving oracles are now printed with a suffixed [!];
  1055 
  1056 
  1057 *** HOL ***
  1058 
  1059 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1060 
  1061 * HOL/inductive package reorganized and improved: now supports mutual
  1062 definitions such as
  1063 
  1064   inductive EVEN ODD
  1065     intrs
  1066       null "0 : EVEN"
  1067       oddI "n : EVEN ==> Suc n : ODD"
  1068       evenI "n : ODD ==> Suc n : EVEN"
  1069 
  1070 new theorem list "elims" contains an elimination rule for each of the
  1071 recursive sets; inductive definitions now handle disjunctive premises
  1072 correctly (also ZF);
  1073 
  1074 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1075 "mutual_induct" no longer exists - the induction rule is always
  1076 contained in "induct";
  1077 
  1078 
  1079 * HOL/datatype package re-implemented and greatly improved: now
  1080 supports mutually recursive datatypes such as
  1081 
  1082   datatype
  1083     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1084             | SUM ('a aexp) ('a aexp)
  1085             | DIFF ('a aexp) ('a aexp)
  1086             | NUM 'a
  1087   and
  1088     'a bexp = LESS ('a aexp) ('a aexp)
  1089             | AND ('a bexp) ('a bexp)
  1090             | OR ('a bexp) ('a bexp)
  1091 
  1092 as well as indirectly recursive datatypes such as
  1093 
  1094   datatype
  1095     ('a, 'b) term = Var 'a
  1096                   | App 'b ((('a, 'b) term) list)
  1097 
  1098 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1099 induction on mutually / indirectly recursive datatypes.
  1100 
  1101 Primrec equations are now stored in theory and can be accessed via
  1102 <function_name>.simps.
  1103 
  1104 INCOMPATIBILITIES:
  1105 
  1106   - Theories using datatypes must now have theory Datatype as an
  1107     ancestor.
  1108   - The specific <typename>.induct_tac no longer exists - use the
  1109     generic induct_tac instead.
  1110   - natE has been renamed to nat.exhaust - use exhaust_tac
  1111     instead of res_inst_tac ... natE. Note that the variable
  1112     names in nat.exhaust differ from the names in natE, this
  1113     may cause some "fragile" proofs to fail.
  1114   - The theorems split_<typename>_case and split_<typename>_case_asm
  1115     have been renamed to <typename>.split and <typename>.split_asm.
  1116   - Since default sorts of type variables are now handled correctly,
  1117     some datatype definitions may have to be annotated with explicit
  1118     sort constraints.
  1119   - Primrec definitions no longer require function name and type
  1120     of recursive argument.
  1121 
  1122 Consider using isatool fixdatatype to adapt your theories and proof
  1123 scripts to the new package (backup your sources first!).
  1124 
  1125 
  1126 * HOL/record package: considerably improved implementation; now
  1127 includes concrete syntax for record types, terms, updates; theorems
  1128 for surjective pairing and splitting !!-bound record variables; proof
  1129 support is as follows:
  1130 
  1131   1) standard conversions (selectors or updates applied to record
  1132 constructor terms) are part of the standard simpset;
  1133 
  1134   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1135 made part of standard simpset and claset via addIffs;
  1136 
  1137   3) a tactic for record field splitting (record_split_tac) is part of
  1138 the standard claset (addSWrapper);
  1139 
  1140 To get a better idea about these rules you may retrieve them via
  1141 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1142 the name of your record type.
  1143 
  1144 The split tactic 3) conceptually simplifies by the following rule:
  1145 
  1146   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1147 
  1148 Thus any record variable that is bound by meta-all will automatically
  1149 blow up into some record constructor term, consequently the
  1150 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1151 solve record problems automatically.
  1152 
  1153 
  1154 * reorganized the main HOL image: HOL/Integ and String loaded by
  1155 default; theory Main includes everything;
  1156 
  1157 * automatic simplification of integer sums and comparisons, using cancellation;
  1158 
  1159 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1160 
  1161 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1162 
  1163 * many new identities for unions, intersections, set difference, etc.;
  1164 
  1165 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1166 called split_if, split_split, split_sum_case and split_nat_case (to go
  1167 with add/delsplits);
  1168 
  1169 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1170 (?x::unit) = (); this is made part of the default simpset, which COULD
  1171 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1172 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1173 unit_abs_eta_conv is added in order to counter the effect of
  1174 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1175 %u.f();
  1176 
  1177 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1178 makes more sense);
  1179 
  1180 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1181   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1182   disjointness reasoning but breaking a few old proofs.
  1183 
  1184 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1185 to 'converse' from 'inverse' (for compatibility with ZF and some
  1186 literature);
  1187 
  1188 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1189 the well-founded relation;
  1190 
  1191 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1192     Compl A.  The "Compl" syntax remains available as input syntax for this
  1193     release ONLY.
  1194 
  1195 * HOL/Update: new theory of function updates:
  1196     f(a:=b) == %x. if x=a then b else f x
  1197 may also be iterated as in f(a:=b,c:=d,...);
  1198 
  1199 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1200 
  1201 * HOL/List:
  1202   - new function list_update written xs[i:=v] that updates the i-th
  1203     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1204   - new function `upt' written [i..j(] which generates the list
  1205     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1206     bound write [i..j], which is a shorthand for [i..j+1(].
  1207   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1208 
  1209 * HOL/Arith:
  1210   - removed 'pred' (predecessor) function;
  1211   - generalized some theorems about n-1;
  1212   - many new laws about "div" and "mod";
  1213   - new laws about greatest common divisors (see theory ex/Primes);
  1214 
  1215 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1216 instead of "inverse";
  1217 
  1218 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1219   of the multiset ordering;
  1220 
  1221 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1222   (not included by default);
  1223 
  1224 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1225 
  1226 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1227   programs, i.e. different program variables may have different types.
  1228 
  1229 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1230   [previously, this check worked only if the rewrite rule was unconditional]
  1231   Now rew can involve either definitions or equalities (either == or =).
  1232 
  1233 
  1234 *** ZF ***
  1235 
  1236 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1237   only the theorems proved on ZF.ML;
  1238 
  1239 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1240   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1241   disjointness reasoning but breaking a few old proofs.
  1242 
  1243 * ZF/Update: new theory of function updates
  1244     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1245   may also be iterated as in f(a:=b,c:=d,...);
  1246 
  1247 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1248 
  1249 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1250   [previously, this check worked only if the rewrite rule was unconditional]
  1251   Now rew can involve either definitions or equalities (either == or =).
  1252 
  1253 * case_tac provided for compatibility with HOL
  1254     (like the old excluded_middle_tac, but with subgoals swapped)
  1255 
  1256 
  1257 *** Internal programming interfaces ***
  1258 
  1259 * Pure: several new basic modules made available for general use, see
  1260 also src/Pure/README;
  1261 
  1262 * improved the theory data mechanism to support encapsulation (data
  1263 kind name replaced by private Object.kind, acting as authorization
  1264 key); new type-safe user interface via functor TheoryDataFun; generic
  1265 print_data function becomes basically useless;
  1266 
  1267 * removed global_names compatibility flag -- all theory declarations
  1268 are qualified by default;
  1269 
  1270 * module Pure/Syntax now offers quote / antiquote translation
  1271 functions (useful for Hoare logic etc. with implicit dependencies);
  1272 see HOL/ex/Antiquote for an example use;
  1273 
  1274 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1275 cterm -> thm;
  1276 
  1277 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1278 subgoal;
  1279 
  1280 * Display.print_goals function moved to Locale.print_goals;
  1281 
  1282 * standard print function for goals supports current_goals_markers
  1283 variable for marking begin of proof, end of proof, start of goal; the
  1284 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1285 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1286 for example;
  1287 
  1288 
  1289 
  1290 New in Isabelle98 (January 1998)
  1291 --------------------------------
  1292 
  1293 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1294 
  1295 * changed lexical syntax of terms / types: dots made part of long
  1296 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1297 
  1298 * simpset (and claset) reference variable replaced by functions
  1299 simpset / simpset_ref;
  1300 
  1301 * no longer supports theory aliases (via merge) and non-trivial
  1302 implicit merge of thms' signatures;
  1303 
  1304 * most internal names of constants changed due to qualified names;
  1305 
  1306 * changed Pure/Sequence interface (see Pure/seq.ML);
  1307 
  1308 
  1309 *** General Changes ***
  1310 
  1311 * hierachically structured name spaces (for consts, types, axms, thms
  1312 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1313 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1314 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1315 long_names for fully qualified output names; NOTE: ML programs
  1316 (special tactics, packages etc.) referring to internal names may have
  1317 to be adapted to cope with fully qualified names; in case of severe
  1318 backward campatibility problems try setting 'global_names' at compile
  1319 time to have enrything declared within a flat name space; one may also
  1320 fine tune name declarations in theories via the 'global' and 'local'
  1321 section;
  1322 
  1323 * reimplemented the implicit simpset and claset using the new anytype
  1324 data filed in signatures; references simpset:simpset ref etc. are
  1325 replaced by functions simpset:unit->simpset and
  1326 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1327 to patch your ML files accordingly;
  1328 
  1329 * HTML output now includes theory graph data for display with Java
  1330 applet or isatool browser; data generated automatically via isatool
  1331 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1332 
  1333 * defs may now be conditional; improved rewrite_goals_tac to handle
  1334 conditional equations;
  1335 
  1336 * defs now admits additional type arguments, using TYPE('a) syntax;
  1337 
  1338 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1339 creates a new theory node; implicit merge of thms' signatures is
  1340 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1341 transfer:theory->thm->thm in (rare) cases;
  1342 
  1343 * improved handling of draft signatures / theories; draft thms (and
  1344 ctyps, cterms) are automatically promoted to real ones;
  1345 
  1346 * slightly changed interfaces for oracles: admit many per theory, named
  1347 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1348 
  1349 * print_goals: optional output of const types (set show_consts and
  1350 show_types);
  1351 
  1352 * improved output of warnings (###) and errors (***);
  1353 
  1354 * subgoal_tac displays a warning if the new subgoal has type variables;
  1355 
  1356 * removed old README and Makefiles;
  1357 
  1358 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1359 
  1360 * removed obsolete init_pps and init_database;
  1361 
  1362 * deleted the obsolete tactical STATE, which was declared by
  1363     fun STATE tacfun st = tacfun st st;
  1364 
  1365 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1366 (which abbreviates $HOME);
  1367 
  1368 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1369 use isatool fixseq to adapt your ML programs (this works for fully
  1370 qualified references to the Sequence structure only!);
  1371 
  1372 * use_thy no longer requires writable current directory; it always
  1373 reloads .ML *and* .thy file, if either one is out of date;
  1374 
  1375 
  1376 *** Classical Reasoner ***
  1377 
  1378 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1379 tactics that use classical reasoning to simplify a subgoal without
  1380 splitting it into several subgoals;
  1381 
  1382 * Safe_tac: like safe_tac but uses the default claset;
  1383 
  1384 
  1385 *** Simplifier ***
  1386 
  1387 * added simplification meta rules:
  1388     (asm_)(full_)simplify: simpset -> thm -> thm;
  1389 
  1390 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1391 logics (again);
  1392 
  1393 * added prems argument to simplification procedures;
  1394 
  1395 * HOL, FOL, ZF: added infix function `addsplits':
  1396   instead of `<simpset> setloop (split_tac <thms>)'
  1397   you can simply write `<simpset> addsplits <thms>'
  1398 
  1399 
  1400 *** Syntax ***
  1401 
  1402 * TYPE('a) syntax for type reflection terms;
  1403 
  1404 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1405 
  1406 * pretty printer: changed order of mixfix annotation preference (again!);
  1407 
  1408 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1409 
  1410 
  1411 *** HOL ***
  1412 
  1413 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1414   with `addloop' of the simplifier to faciliate case splitting in premises.
  1415 
  1416 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1417 
  1418 * HOL/Auth: new protocol proofs including some for the Internet
  1419   protocol TLS;
  1420 
  1421 * HOL/Map: new theory of `maps' a la VDM;
  1422 
  1423 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1424 cancelling out common nat summands from =, <, <= (in)equalities, or
  1425 differences; simplification procedures nat_cancel_factor for
  1426 cancelling common factor from =, <, <= (in)equalities over natural
  1427 sums; nat_cancel contains both kinds of procedures, it is installed by
  1428 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1429 
  1430 * HOL/simplifier: terms of the form
  1431   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1432   are rewritten to
  1433   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1434   and those of the form
  1435   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1436   are rewritten to
  1437   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1438 
  1439 * HOL/datatype
  1440   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1441 
  1442   P(t_case f1 ... fn x) =
  1443      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1444         ...
  1445        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1446      )
  1447 
  1448   and a theorem `split_t_case_asm' of the form
  1449 
  1450   P(t_case f1 ... fn x) =
  1451     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1452         ...
  1453        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1454      )
  1455   which can be added to a simpset via `addsplits'. The existing theorems
  1456   expand_list_case and expand_option_case have been renamed to
  1457   split_list_case and split_option_case.
  1458 
  1459 * HOL/Arithmetic:
  1460   - `pred n' is automatically converted to `n-1'.
  1461     Users are strongly encouraged not to use `pred' any longer,
  1462     because it will disappear altogether at some point.
  1463   - Users are strongly encouraged to write "0 < n" rather than
  1464     "n ~= 0". Theorems and proof tools have been modified towards this
  1465     `standard'.
  1466 
  1467 * HOL/Lists:
  1468   the function "set_of_list" has been renamed "set" (and its theorems too);
  1469   the function "nth" now takes its arguments in the reverse order and
  1470   has acquired the infix notation "!" as in "xs!n".
  1471 
  1472 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1473 
  1474 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1475   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1476 
  1477 * HOL/record: extensible records with schematic structural subtyping
  1478 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1479 still lacks various theorems and concrete record syntax;
  1480 
  1481 
  1482 *** HOLCF ***
  1483 
  1484 * removed "axioms" and "generated by" sections;
  1485 
  1486 * replaced "ops" section by extended "consts" section, which is capable of
  1487   handling the continuous function space "->" directly;
  1488 
  1489 * domain package:
  1490   . proves theorems immediately and stores them in the theory,
  1491   . creates hierachical name space,
  1492   . now uses normal mixfix annotations (instead of cinfix...),
  1493   . minor changes to some names and values (for consistency),
  1494   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1495   . separator between mutual domain defs: changed "," to "and",
  1496   . improved handling of sort constraints;  now they have to
  1497     appear on the left-hand side of the equations only;
  1498 
  1499 * fixed LAM <x,y,zs>.b syntax;
  1500 
  1501 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1502 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1503 
  1504 
  1505 *** FOL and ZF ***
  1506 
  1507 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1508   with `addloop' of the simplifier to faciliate case splitting in premises.
  1509 
  1510 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1511 in HOL, they strip ALL and --> from proved theorems;
  1512 
  1513 
  1514 
  1515 New in Isabelle94-8 (May 1997)
  1516 ------------------------------
  1517 
  1518 *** General Changes ***
  1519 
  1520 * new utilities to build / run / maintain Isabelle etc. (in parts
  1521 still somewhat experimental); old Makefiles etc. still functional;
  1522 
  1523 * new 'Isabelle System Manual';
  1524 
  1525 * INSTALL text, together with ./configure and ./build scripts;
  1526 
  1527 * reimplemented type inference for greater efficiency, better error
  1528 messages and clean internal interface;
  1529 
  1530 * prlim command for dealing with lots of subgoals (an easier way of
  1531 setting goals_limit);
  1532 
  1533 
  1534 *** Syntax ***
  1535 
  1536 * supports alternative (named) syntax tables (parser and pretty
  1537 printer); internal interface is provided by add_modesyntax(_i);
  1538 
  1539 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1540 be used in conjunction with the Isabelle symbol font; uses the
  1541 "symbols" syntax table;
  1542 
  1543 * added token_translation interface (may translate name tokens in
  1544 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1545 the current print_mode); IMPORTANT: user print translation functions
  1546 are responsible for marking newly introduced bounds
  1547 (Syntax.mark_boundT);
  1548 
  1549 * token translations for modes "xterm" and "xterm_color" that display
  1550 names in bold, underline etc. or colors (which requires a color
  1551 version of xterm);
  1552 
  1553 * infixes may now be declared with names independent of their syntax;
  1554 
  1555 * added typed_print_translation (like print_translation, but may
  1556 access type of constant);
  1557 
  1558 
  1559 *** Classical Reasoner ***
  1560 
  1561 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  1562 some limitations.  Blast_tac...
  1563   + ignores addss, addbefore, addafter; this restriction is intrinsic
  1564   + ignores elimination rules that don't have the correct format
  1565         (the conclusion MUST be a formula variable)
  1566   + ignores types, which can make HOL proofs fail
  1567   + rules must not require higher-order unification, e.g. apply_type in ZF
  1568     [message "Function Var's argument not a bound variable" relates to this]
  1569   + its proof strategy is more general but can actually be slower
  1570 
  1571 * substitution with equality assumptions no longer permutes other
  1572 assumptions;
  1573 
  1574 * minor changes in semantics of addafter (now called addaltern); renamed
  1575 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  1576 (and access functions for it);
  1577 
  1578 * improved combination of classical reasoner and simplifier:
  1579   + functions for handling clasimpsets
  1580   + improvement of addss: now the simplifier is called _after_ the
  1581     safe steps.
  1582   + safe variant of addss called addSss: uses safe simplifications
  1583     _during_ the safe steps. It is more complete as it allows multiple
  1584     instantiations of unknowns (e.g. with slow_tac).
  1585 
  1586 *** Simplifier ***
  1587 
  1588 * added interface for simplification procedures (functions that
  1589 produce *proven* rewrite rules on the fly, depending on current
  1590 redex);
  1591 
  1592 * ordering on terms as parameter (used for ordered rewriting);
  1593 
  1594 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  1595 
  1596 * the solver is now split into a safe and an unsafe part.
  1597 This should be invisible for the normal user, except that the
  1598 functions setsolver and addsolver have been renamed to setSolver and
  1599 addSolver; added safe_asm_full_simp_tac;
  1600 
  1601 
  1602 *** HOL ***
  1603 
  1604 * a generic induction tactic `induct_tac' which works for all datatypes and
  1605 also for type `nat';
  1606 
  1607 * a generic case distinction tactic `exhaust_tac' which works for all
  1608 datatypes and also for type `nat';
  1609 
  1610 * each datatype comes with a function `size';
  1611 
  1612 * patterns in case expressions allow tuple patterns as arguments to
  1613 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1614 
  1615 * primrec now also works with type nat;
  1616 
  1617 * recdef: a new declaration form, allows general recursive functions to be
  1618 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1619 
  1620 * the constant for negation has been renamed from "not" to "Not" to
  1621 harmonize with FOL, ZF, LK, etc.;
  1622 
  1623 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1624 infinite lists;
  1625 
  1626 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1627 
  1628 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1629 problems in commutative rings, using axiomatic type classes for + and *;
  1630 
  1631 * more examples in HOL/MiniML and HOL/Auth;
  1632 
  1633 * more default rewrite rules for quantifiers, union/intersection;
  1634 
  1635 * a new constant `arbitrary == @x.False';
  1636 
  1637 * HOLCF/IOA replaces old HOL/IOA;
  1638 
  1639 * HOLCF changes: derived all rules and arities
  1640   + axiomatic type classes instead of classes
  1641   + typedef instead of faking type definitions
  1642   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1643   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1644   + eliminated the types void, one, tr
  1645   + use unit lift and bool lift (with translations) instead of one and tr
  1646   + eliminated blift from Lift3.thy (use Def instead of blift)
  1647   all eliminated rules are derived as theorems --> no visible changes ;
  1648 
  1649 
  1650 *** ZF ***
  1651 
  1652 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1653 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1654 as ZF_cs addSIs [equalityI];
  1655 
  1656 
  1657 
  1658 New in Isabelle94-7 (November 96)
  1659 ---------------------------------
  1660 
  1661 * allowing negative levels (as offsets) in prlev and choplev;
  1662 
  1663 * super-linear speedup for large simplifications;
  1664 
  1665 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1666 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1667 FAIL); can suppress it using the command Delsimps (ex_simps @
  1668 all_simps); De Morgan laws are also now included, by default;
  1669 
  1670 * improved printing of ==>  :  ~:
  1671 
  1672 * new object-logic "Sequents" adds linear logic, while replacing LK
  1673 and Modal (thanks to Sara Kalvala);
  1674 
  1675 * HOL/Auth: correctness proofs for authentication protocols;
  1676 
  1677 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1678 examples on HOL/Auth);
  1679 
  1680 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1681 the rewriter and classical reasoner simultaneously;
  1682 
  1683 * function uresult no longer returns theorems in "standard" format;
  1684 regain previous version by: val uresult = standard o uresult;
  1685 
  1686 
  1687 
  1688 New in Isabelle94-6
  1689 -------------------
  1690 
  1691 * oracles -- these establish an interface between Isabelle and trusted
  1692 external reasoners, which may deliver results as theorems;
  1693 
  1694 * proof objects (in particular record all uses of oracles);
  1695 
  1696 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1697 
  1698 * "constdefs" section in theory files;
  1699 
  1700 * "primrec" section (HOL) no longer requires names;
  1701 
  1702 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1703 
  1704 
  1705 
  1706 New in Isabelle94-5
  1707 -------------------
  1708 
  1709 * reduced space requirements;
  1710 
  1711 * automatic HTML generation from theories;
  1712 
  1713 * theory files no longer require "..." (quotes) around most types;
  1714 
  1715 * new examples, including two proofs of the Church-Rosser theorem;
  1716 
  1717 * non-curried (1994) version of HOL is no longer distributed;
  1718 
  1719 
  1720 
  1721 New in Isabelle94-4
  1722 -------------------
  1723 
  1724 * greatly reduced space requirements;
  1725 
  1726 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1727 
  1728 * searchable theorem database (see the section "Retrieving theorems" on
  1729 page 8 of the Reference Manual);
  1730 
  1731 * new examples, including Grabczewski's monumental case study of the
  1732 Axiom of Choice;
  1733 
  1734 * The previous version of HOL renamed to Old_HOL;
  1735 
  1736 * The new version of HOL (previously called CHOL) uses a curried syntax
  1737 for functions.  Application looks like f a b instead of f(a,b);
  1738 
  1739 * Mutually recursive inductive definitions finally work in HOL;
  1740 
  1741 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1742 translates to the operator "split";
  1743 
  1744 
  1745 
  1746 New in Isabelle94-3
  1747 -------------------
  1748 
  1749 * new infix operator, addss, allowing the classical reasoner to
  1750 perform simplification at each step of its search.  Example:
  1751         fast_tac (cs addss ss)
  1752 
  1753 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1754 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1755 look like (a,b) instead of <a,b>;
  1756 
  1757 * PLEASE NOTE: CHOL will eventually replace HOL!
  1758 
  1759 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1760 It translates to the operator "split".  A new theory of integers is available;
  1761 
  1762 * In ZF, integer numerals now denote two's-complement binary integers.
  1763 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1764 
  1765 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1766 of the Axiom of Choice;
  1767 
  1768 
  1769 
  1770 New in Isabelle94-2
  1771 -------------------
  1772 
  1773 * Significantly faster resolution;
  1774 
  1775 * the different sections in a .thy file can now be mixed and repeated
  1776 freely;
  1777 
  1778 * Database of theorems for FOL, HOL and ZF.  New
  1779 commands including qed, qed_goal and bind_thm store theorems in the database.
  1780 
  1781 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1782 a given theory (thms_of), or find out what theory a theorem was proved in
  1783 (theory_of_thm);
  1784 
  1785 * Bugs fixed in the inductive definition and datatype packages;
  1786 
  1787 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1788 and HOL_dup_cs obsolete;
  1789 
  1790 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1791 have been removed;
  1792 
  1793 * Simpler definition of function space in ZF;
  1794 
  1795 * new results about cardinal and ordinal arithmetic in ZF;
  1796 
  1797 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1798 types;
  1799 
  1800 
  1801 $Id$