NEWS
author wenzelm
Fri Oct 05 21:52:39 2001 +0200 (2001-10-05)
changeset 11701 3d51fbf81c17
parent 11700 a0e6bda62b7b
child 11702 ebfe5ba905b0
permissions -rw-r--r--
sane numerals (stage 1): added generic 1, removed 1' and 2 on nat,
"num" syntax (still with "#"), Numeral0, Numeral1;
     1 
     2 Isabelle NEWS -- history user-relevant changes
     3 ==============================================
     4 
     5 New in Isabelle2001 (?? 2001)
     6 -----------------------------
     7 
     8 *** Document preparation ***
     9 
    10 * support bold style (for single symbols only), input syntax is like
    11 this: "\<^bold>\<alpha>" or "\<^bold>A";
    12 
    13 * \<bullet> is no output as bold \cdot by default, which looks much
    14 better in printed text;
    15 
    16 
    17 *** Isar ***
    18 
    19 * renamed "antecedent" case to "rule_context";
    20 
    21 * improved proof by cases and induction:
    22   - moved induct/cases attributes to Pure;
    23   - added 'print_induct_rules' (covered by help item in Proof General > 3.3);
    24   - generic setup instantiated for FOL and HOL;
    25   - removed obsolete "(simplified)" and "(stripped)" options;
    26 
    27 * HOL: 'recdef' now fails on unfinished automated proofs, use
    28 "(permissive)" option to recover old behavior;
    29 
    30 * HOL: 'inductive' now longer features separate (collective)
    31 attributes for 'intros';
    32 
    33 
    34 *** HOL ***
    35 
    36 * HOL: linorder_less_split superseded by linorder_cases;
    37 
    38 * HOL: added "The" definite description operator; move Hilbert's "Eps"
    39 to peripheral theory "Hilbert_Choice";
    40 
    41 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
    42 in this (rare) case use:
    43 
    44   delSWrapper "split_all_tac"
    45   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
    46 
    47 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
    48 MAY FAIL;
    49 
    50 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
    51 Isabelle's type classes, ^ on functions and relations has too general
    52 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
    53 necessary to attach explicit type constraints;
    54 
    55 * HOL: syntax translations now work properly with numerals and records
    56 expressions;
    57 
    58 * HOL/GroupTheory: group theory examples including Sylow's theorem, by
    59 Florian Kammüller;
    60 
    61 * HOL: eliminated global items
    62 
    63   const "()" -> "Product_Type.Unity"
    64   type "unit" -> "Product_Type.unit"
    65 
    66 
    67 *** ZF ***
    68 
    69 * ZF: the integer library now covers quotients and remainders, with
    70 many laws relating division to addition, multiplication, etc.;
    71 
    72 
    73 *** General ***
    74 
    75 * Meta-level proof terms (by Stefan Berghofer), see also ref manual;
    76 
    77 * new token syntax "num" for plain numerals (without "#" of "xnum");
    78 potential INCOMPATIBILITY, since -0, -1 etc. are now separate tokens,
    79 so expressions involving minus need to be spaced properly;
    80 
    81 * Classical reasoner: renamed addaltern to addafter, addSaltern to
    82 addSafter;
    83 
    84 * syntax: support non-oriented infixes;
    85 
    86 * print modes "type_brackets" and "no_type_brackets" control output of
    87 nested => (types); the default behavior is "brackets";
    88 
    89 * system: support Poly/ML 4.1.1 (now able to manage large heaps);
    90 
    91 * system: Proof General keywords specification is now part of the
    92 Isabelle distribution (see etc/isar-keywords.el);
    93 
    94 * system: smart selection of Isabelle process versus Isabelle
    95 interface, accommodates case-insensitive file systems (e.g. HFS+); may
    96 run both "isabelle" and "Isabelle" even if file names are badly
    97 damaged (executable inspects the case of the first letter of its own
    98 name); added separate "isabelle-process" and "isabelle-interface";
    99 
   100 
   101 
   102 New in Isabelle99-2 (February 2001)
   103 -----------------------------------
   104 
   105 *** Overview of INCOMPATIBILITIES ***
   106 
   107 * HOL: please note that theories in the Library and elsewhere often use the
   108 new-style (Isar) format; to refer to their theorems in an ML script you must
   109 bind them to ML identifers by e.g.	val thm_name = thm "thm_name";
   110 
   111 * HOL: inductive package no longer splits induction rule aggressively,
   112 but only as far as specified by the introductions given; the old
   113 format may be recovered via ML function complete_split_rule or attribute
   114 'split_rule (complete)';
   115 
   116 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   117 gfp_Tarski to gfp_unfold;
   118 
   119 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   120 
   121 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   122 relation); infix "^^" has been renamed "``"; infix "``" has been
   123 renamed "`"; "univalent" has been renamed "single_valued";
   124 
   125 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   126 operation;
   127 
   128 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   129 
   130 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   131 
   132 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   133 consequence, it is no longer monotonic wrt. the local goal context
   134 (which is now passed through the inductive cases);
   135 
   136 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   137 \<gg> to \<ggreater>;
   138 
   139 
   140 *** Document preparation ***
   141 
   142 * \isabellestyle{NAME} selects version of Isabelle output (currently
   143 available: are "it" for near math-mode best-style output, "sl" for
   144 slanted text style, and "tt" for plain type-writer; if no
   145 \isabellestyle command is given, output is according to slanted
   146 type-writer);
   147 
   148 * support sub/super scripts (for single symbols only), input syntax is
   149 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   150 
   151 * some more standard symbols; see Appendix A of the system manual for
   152 the complete list of symbols defined in isabellesym.sty;
   153 
   154 * improved isabelle style files; more abstract symbol implementation
   155 (should now use \isamath{...} and \isatext{...} in custom symbol
   156 definitions);
   157 
   158 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   159 state; Note that presentation of goal states does not conform to
   160 actual human-readable proof documents.  Please do not include goal
   161 states into document output unless you really know what you are doing!
   162 
   163 * proper indentation of antiquoted output with proportional LaTeX
   164 fonts;
   165 
   166 * no_document ML operator temporarily disables LaTeX document
   167 generation;
   168 
   169 * isatool unsymbolize tunes sources for plain ASCII communication;
   170 
   171 
   172 *** Isar ***
   173 
   174 * Pure: Isar now suffers initial goal statements to contain unbound
   175 schematic variables (this does not conform to actual readable proof
   176 documents, due to unpredictable outcome and non-compositional proof
   177 checking); users who know what they are doing may use schematic goals
   178 for Prolog-style synthesis of proven results;
   179 
   180 * Pure: assumption method (an implicit finishing) now handles actual
   181 rules as well;
   182 
   183 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   184 initial goal, declare "that" only as Pure intro (only for single
   185 steps); the "that" rule assumption may now be involved in implicit
   186 finishing, thus ".." becomes a feasible for trivial obtains;
   187 
   188 * Pure: default proof step now includes 'intro_classes'; thus trivial
   189 instance proofs may be performed by "..";
   190 
   191 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   192 statements as well;
   193 
   194 * Pure: more robust selection of calculational rules;
   195 
   196 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   197 rule (as well as the assumption rule);
   198 
   199 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   200 lemmas, using the graph browser tool;
   201 
   202 * Pure: predict failure of "show" in interactive mode;
   203 
   204 * Pure: 'thms_containing' now takes actual terms as arguments;
   205 
   206 * HOL: improved method 'induct' --- now handles non-atomic goals
   207 (potential INCOMPATIBILITY); tuned error handling;
   208 
   209 * HOL: cases and induct rules now provide explicit hints about the
   210 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   211 any remaining facts are inserted into the goal verbatim;
   212 
   213 * HOL: local contexts (aka cases) may now contain term bindings as
   214 well; the 'cases' and 'induct' methods new provide a ?case binding for
   215 the result to be shown in each case;
   216 
   217 * HOL: added 'recdef_tc' command;
   218 
   219 * isatool convert assists in eliminating legacy ML scripts;
   220 
   221 
   222 *** HOL ***
   223 
   224 * HOL/Library: a collection of generic theories to be used together
   225 with main HOL; the theory loader path already includes this directory
   226 by default; the following existing theories have been moved here:
   227 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   228 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   229 
   230 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   231 modelling and verification task performed in Isabelle/HOL +
   232 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   233 
   234 * HOL/Algebra: special summation operator SUM no longer exists, it has
   235 been replaced by setsum; infix 'assoc' now has priority 50 (like
   236 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   237 'domain', this makes the theory consistent with mathematical
   238 literature;
   239 
   240 * HOL basics: added overloaded operations "inverse" and "divide"
   241 (infix "/"), syntax for generic "abs" operation, generic summation
   242 operator \<Sum>;
   243 
   244 * HOL/typedef: simplified package, provide more useful rules (see also
   245 HOL/subset.thy);
   246 
   247 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   248 now expressed as a proper nested rule (old-style tactic scripts may
   249 require atomize_strip_tac to cope with non-atomic premises);
   250 
   251 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   252 to "split_conv" (old name still available for compatibility);
   253 
   254 * HOL: improved concrete syntax for strings (e.g. allows translation
   255 rules with string literals);
   256 
   257 * HOL-Hyperreal: a new target, extending HOL-Real with the hyperreals
   258 and Fleuriot's mechanization of analysis;
   259 
   260 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   261 
   262 
   263 *** CTT ***
   264 
   265 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   266 "lam" is displayed as TWO lambda-symbols
   267 
   268 * CTT: theory Main now available, containing everything (that is, Bool
   269 and Arith);
   270 
   271 
   272 *** General ***
   273 
   274 * Pure: the Simplifier has been implemented properly as a derived rule
   275 outside of the actual kernel (at last!); the overall performance
   276 penalty in practical applications is about 50%, while reliability of
   277 the Isabelle inference kernel has been greatly improved;
   278 
   279 * print modes "brackets" and "no_brackets" control output of nested =>
   280 (types) and ==> (props); the default behaviour is "brackets";
   281 
   282 * Provers: fast_tac (and friends) now handle actual object-logic rules
   283 as assumptions as well;
   284 
   285 * system: support Poly/ML 4.0;
   286 
   287 * system: isatool install handles KDE version 1 or 2;
   288 
   289 
   290 
   291 New in Isabelle99-1 (October 2000)
   292 ----------------------------------
   293 
   294 *** Overview of INCOMPATIBILITIES ***
   295 
   296 * HOL: simplification of natural numbers is much changed; to partly
   297 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   298 issue the following ML commands:
   299 
   300   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   301   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   302 
   303 * HOL: simplification no longer dives into case-expressions; this is
   304 controlled by "t.weak_case_cong" for each datatype t;
   305 
   306 * HOL: nat_less_induct renamed to less_induct;
   307 
   308 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   309 fixsome to patch .thy and .ML sources automatically;
   310 
   311   select_equality  -> some_equality
   312   select_eq_Ex     -> some_eq_ex
   313   selectI2EX       -> someI2_ex
   314   selectI2         -> someI2
   315   selectI          -> someI
   316   select1_equality -> some1_equality
   317   Eps_sym_eq       -> some_sym_eq_trivial
   318   Eps_eq           -> some_eq_trivial
   319 
   320 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   321 
   322 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   323 instead);
   324 
   325 * HOL: the recursion equations generated by 'recdef' are now called
   326 f.simps instead of f.rules;
   327 
   328 * HOL: qed_spec_mp now also handles bounded ALL as well;
   329 
   330 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   331 sometimes be needed;
   332 
   333 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   334 
   335 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   336 
   337 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   338 product is now "<*>" instead of "Times"; the lexicographic product is
   339 now "<*lex*>" instead of "**";
   340 
   341 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   342 of main HOL, but was unused); better use HOL's datatype package;
   343 
   344 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   345 the old syntax may be recovered as follows:
   346 
   347   syntax (symbols)
   348     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   349       (infixl "\\<oplus>" 100)
   350 
   351 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   352 
   353 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   354 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   355 internally;
   356 
   357 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   358 changed from A/r to A//r;
   359 
   360 * ZF: new treatment of arithmetic (nat & int) may break some old
   361 proofs;
   362 
   363 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   364 rulify -> rule_format, elimify -> elim_format, ...);
   365 
   366 * Isar/Provers: intro/elim/dest attributes changed; renamed
   367 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   368 should have to change intro!! to intro? only); replaced "delrule" by
   369 "rule del";
   370 
   371 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   372 
   373 * Provers: strengthened force_tac by using new first_best_tac;
   374 
   375 * LaTeX document preparation: several changes of isabelle.sty (see
   376 lib/texinputs);
   377 
   378 
   379 *** Document preparation ***
   380 
   381 * formal comments (text blocks etc.) in new-style theories may now
   382 contain antiquotations of thm/prop/term/typ/text to be presented
   383 according to latex print mode; concrete syntax is like this:
   384 @{term[show_types] "f(x) = a + x"};
   385 
   386 * isatool mkdir provides easy setup of Isabelle session directories,
   387 including proper document sources;
   388 
   389 * generated LaTeX sources are now deleted after successful run
   390 (isatool document -c); may retain a copy somewhere else via -D option
   391 of isatool usedir;
   392 
   393 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   394 style files, achieving self-contained LaTeX sources and simplifying
   395 LaTeX debugging;
   396 
   397 * old-style theories now produce (crude) LaTeX output as well;
   398 
   399 * browser info session directories are now self-contained (may be put
   400 on WWW server seperately); improved graphs of nested sessions; removed
   401 graph for 'all sessions';
   402 
   403 * several improvements in isabelle style files; \isabellestyle{it}
   404 produces fake math mode output; \isamarkupheader is now \section by
   405 default; see lib/texinputs/isabelle.sty etc.;
   406 
   407 
   408 *** Isar ***
   409 
   410 * Isar/Pure: local results and corresponding term bindings are now
   411 subject to Hindley-Milner polymorphism (similar to ML); this
   412 accommodates incremental type-inference very nicely;
   413 
   414 * Isar/Pure: new derived language element 'obtain' supports
   415 generalized existence reasoning;
   416 
   417 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   418 support accumulation of results, without applying any rules yet;
   419 useful to collect intermediate results without explicit name
   420 references, and for use with transitivity rules with more than 2
   421 premises;
   422 
   423 * Isar/Pure: scalable support for case-analysis type proofs: new
   424 'case' language element refers to local contexts symbolically, as
   425 produced by certain proof methods; internally, case names are attached
   426 to theorems as "tags";
   427 
   428 * Isar/Pure: theory command 'hide' removes declarations from
   429 class/type/const name spaces;
   430 
   431 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   432 indicate potential overloading;
   433 
   434 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   435 
   436 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   437 "{a,b,c}" instead of {a,b,c};
   438 
   439 * Isar/Pure now provides its own version of intro/elim/dest
   440 attributes; useful for building new logics, but beware of confusion
   441 with the version in Provers/classical;
   442 
   443 * Isar/Pure: the local context of (non-atomic) goals is provided via
   444 case name 'antecedent';
   445 
   446 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   447 to the current context is now done automatically);
   448 
   449 * Isar/Pure: theory command 'method_setup' provides a simple interface
   450 for definining proof methods in ML;
   451 
   452 * Isar/Provers: intro/elim/dest attributes changed; renamed
   453 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   454 most cases, one should have to change intro!! to intro? only);
   455 replaced "delrule" by "rule del";
   456 
   457 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   458 'symmetric' attribute (the latter supercedes [RS sym]);
   459 
   460 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   461 method modifier); 'simp' method: 'only:' modifier removes loopers as
   462 well (including splits);
   463 
   464 * Isar/Provers: Simplifier and Classical methods now support all kind
   465 of modifiers used in the past, including 'cong', 'iff', etc.
   466 
   467 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   468 of Simplifier and Classical reasoner);
   469 
   470 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   471 now support named cases; major packages (inductive, datatype, primrec,
   472 recdef) support case names and properly name parameters;
   473 
   474 * Isar/HOL: new transitivity rules for substitution in inequalities --
   475 monotonicity conditions are extracted to be proven at end of
   476 calculations;
   477 
   478 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   479 method anyway;
   480 
   481 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   482 split_if split_if_asm; datatype package provides theorems foo.splits =
   483 foo.split foo.split_asm for each datatype;
   484 
   485 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   486 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   487 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   488 use "(cases (simplified))" method in proper proof texts);
   489 
   490 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   491 
   492 * Isar: names of theorems etc. may be natural numbers as well;
   493 
   494 * Isar: 'pr' command: optional arguments for goals_limit and
   495 ProofContext.prems_limit; no longer prints theory contexts, but only
   496 proof states;
   497 
   498 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   499 additional print modes to be specified; e.g. "pr(latex)" will print
   500 proof state according to the Isabelle LaTeX style;
   501 
   502 * Isar: improved support for emulating tactic scripts, including proof
   503 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   504 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   505 (for HOL datatypes);
   506 
   507 * Isar: simplified (more robust) goal selection of proof methods: 1st
   508 goal, all goals, or explicit goal specifier (tactic emulation); thus
   509 'proof method scripts' have to be in depth-first order;
   510 
   511 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   512 
   513 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   514 should instead use individual commands for printing items
   515 (print_commands, print_methods etc.);
   516 
   517 * Isar: added 'nothing' --- the empty list of theorems;
   518 
   519 
   520 *** HOL ***
   521 
   522 * HOL/MicroJava: formalization of a fragment of Java, together with a
   523 corresponding virtual machine and a specification of its bytecode
   524 verifier and a lightweight bytecode verifier, including proofs of
   525 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   526 Cornelia Pusch (see also the homepage of project Bali at
   527 http://isabelle.in.tum.de/Bali/);
   528 
   529 * HOL/Algebra: new theory of rings and univariate polynomials, by
   530 Clemens Ballarin;
   531 
   532 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   533 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   534 Rasmussen;
   535 
   536 * HOL/Lattice: fundamental concepts of lattice theory and order
   537 structures, including duals, properties of bounds versus algebraic
   538 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   539 Theorem for complete lattices etc.; may also serve as a demonstration
   540 for abstract algebraic reasoning using axiomatic type classes, and
   541 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   542 
   543 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   544 von Oheimb;
   545 
   546 * HOL/IMPP: extension of IMP with local variables and mutually
   547 recursive procedures, by David von Oheimb;
   548 
   549 * HOL/Lambda: converted into new-style theory and document;
   550 
   551 * HOL/ex/Multiquote: example of multiple nested quotations and
   552 anti-quotations -- basically a generalized version of de-Bruijn
   553 representation; very useful in avoiding lifting of operations;
   554 
   555 * HOL/record: added general record equality rule to simpset; fixed
   556 select-update simplification procedure to handle extended records as
   557 well; admit "r" as field name;
   558 
   559 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   560 other numeric types and also as the identity of groups, rings, etc.;
   561 
   562 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   563 Types nat and int belong to this axclass;
   564 
   565 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   566    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   567    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   568   two terms #m*u and #n*u are replaced by #(m+n)*u
   569     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   570   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   571     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   572 
   573 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   574 powerful prover for predicate logic but knows nothing of clasets; see
   575 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   576 
   577 * HOL: new version of "case_tac" subsumes both boolean case split and
   578 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   579 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   580 
   581 * HOL: simplification no longer dives into case-expressions: only the
   582 selector expression is simplified, but not the remaining arms; to
   583 enable full simplification of case-expressions for datatype t, you may
   584 remove t.weak_case_cong from the simpset, either globally (Delcongs
   585 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   586 
   587 * HOL/recdef: the recursion equations generated by 'recdef' for
   588 function 'f' are now called f.simps instead of f.rules; if all
   589 termination conditions are proved automatically, these simplification
   590 rules are added to the simpset, as in primrec; rules may be named
   591 individually as well, resulting in a separate list of theorems for
   592 each equation;
   593 
   594 * HOL/While is a new theory that provides a while-combinator. It
   595 permits the definition of tail-recursive functions without the
   596 provision of a termination measure. The latter is necessary once the
   597 invariant proof rule for while is applied.
   598 
   599 * HOL: new (overloaded) notation for the set of elements below/above
   600 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   601 
   602 * HOL: theorems impI, allI, ballI bound as "strip";
   603 
   604 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   605 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   606 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   607 
   608 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   609 
   610 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   611 main HOL, but was unused);
   612 
   613 * HOL: fewer consts declared as global (e.g. have to refer to
   614 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   615 
   616 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   617 in case of overlap with user translations (e.g. judgements over
   618 tuples); (note that the underlying logical represenation is still
   619 bogus);
   620 
   621 
   622 *** ZF ***
   623 
   624 * ZF: simplification automatically cancels common terms in arithmetic
   625 expressions over nat and int;
   626 
   627 * ZF: new treatment of nat to minimize type-checking: all operators
   628 coerce their operands to a natural number using the function natify,
   629 making the algebraic laws unconditional;
   630 
   631 * ZF: as above, for int: operators coerce their operands to an integer
   632 using the function intify;
   633 
   634 * ZF: the integer library now contains many of the usual laws for the
   635 orderings, including $<=, and monotonicity laws for $+ and $*;
   636 
   637 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
   638 simplification;
   639 
   640 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
   641 to the simplifier and classical reasoner simultaneously;
   642 
   643 
   644 *** General ***
   645 
   646 * Provers: blast_tac now handles actual object-logic rules as
   647 assumptions; note that auto_tac uses blast_tac internally as well;
   648 
   649 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
   650 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
   651 
   652 * Provers: delrules now handles destruct rules as well (no longer need
   653 explicit make_elim);
   654 
   655 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
   656   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   657 use instead the strong form,
   658   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   659 in HOL, FOL and ZF the function cla_make_elim will create such rules
   660 from destruct-rules;
   661 
   662 * Provers: Simplifier.easy_setup provides a fast path to basic
   663 Simplifier setup for new object-logics;
   664 
   665 * Pure: AST translation rules no longer require constant head on LHS;
   666 
   667 * Pure: improved name spaces: ambiguous output is qualified; support
   668 for hiding of names;
   669 
   670 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
   671 XSYMBOL_HOME; no longer need to do manual configuration in most
   672 situations;
   673 
   674 * system: compression of ML heaps images may now be controlled via -c
   675 option of isabelle and isatool usedir (currently only observed by
   676 Poly/ML);
   677 
   678 * system: isatool installfonts may handle X-Symbol fonts as well (very
   679 useful for remote X11);
   680 
   681 * system: provide TAGS file for Isabelle sources;
   682 
   683 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
   684 order;
   685 
   686 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
   687 timing flag supersedes proof_timing and Toplevel.trace;
   688 
   689 * ML: new combinators |>> and |>>> for incremental transformations
   690 with secondary results (e.g. certain theory extensions):
   691 
   692 * ML: PureThy.add_defs gets additional argument to indicate potential
   693 overloading (usually false);
   694 
   695 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
   696 results;
   697 
   698 
   699 
   700 New in Isabelle99 (October 1999)
   701 --------------------------------
   702 
   703 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   704 
   705 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
   706 are no longer simplified.  (This allows the simplifier to unfold recursive
   707 functional programs.)  To restore the old behaviour, declare
   708 
   709     Delcongs [if_weak_cong];
   710 
   711 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
   712 complement;
   713 
   714 * HOL: the predicate "inj" is now defined by translation to "inj_on";
   715 
   716 * HOL/datatype: mutual_induct_tac no longer exists --
   717   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
   718 
   719 * HOL/typedef: fixed type inference for representing set; type
   720 arguments now have to occur explicitly on the rhs as type constraints;
   721 
   722 * ZF: The con_defs part of an inductive definition may no longer refer
   723 to constants declared in the same theory;
   724 
   725 * HOL, ZF: the function mk_cases, generated by the inductive
   726 definition package, has lost an argument.  To simplify its result, it
   727 uses the default simpset instead of a supplied list of theorems.
   728 
   729 * HOL/List: the constructors of type list are now Nil and Cons;
   730 
   731 * Simplifier: the type of the infix ML functions
   732         setSSolver addSSolver setSolver addSolver
   733 is now  simpset * solver -> simpset  where `solver' is a new abstract type
   734 for packaging solvers. A solver is created via
   735         mk_solver: string -> (thm list -> int -> tactic) -> solver
   736 where the string argument is only a comment.
   737 
   738 
   739 *** Proof tools ***
   740 
   741 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
   742 decision procedure for linear arithmetic. Currently it is used for
   743 types `nat', `int', and `real' in HOL (see below); it can, should and
   744 will be instantiated for other types and logics as well.
   745 
   746 * The simplifier now accepts rewrite rules with flexible heads, eg
   747      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
   748   They are applied like any rule with a non-pattern lhs, i.e. by first-order
   749   matching.
   750 
   751 
   752 *** General ***
   753 
   754 * New Isabelle/Isar subsystem provides an alternative to traditional
   755 tactical theorem proving; together with the ProofGeneral/isar user
   756 interface it offers an interactive environment for developing human
   757 readable proof documents (Isar == Intelligible semi-automated
   758 reasoning); for further information see isatool doc isar-ref,
   759 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
   760 
   761 * improved and simplified presentation of theories: better HTML markup
   762 (including colors), graph views in several sizes; isatool usedir now
   763 provides a proper interface for user theories (via -P option); actual
   764 document preparation based on (PDF)LaTeX is available as well (for
   765 new-style theories only); see isatool doc system for more information;
   766 
   767 * native support for Proof General, both for classic Isabelle and
   768 Isabelle/Isar;
   769 
   770 * ML function thm_deps visualizes dependencies of theorems and lemmas,
   771 using the graph browser tool;
   772 
   773 * Isabelle manuals now also available as PDF;
   774 
   775 * theory loader rewritten from scratch (may not be fully
   776 bug-compatible); old loadpath variable has been replaced by show_path,
   777 add_path, del_path, reset_path functions; new operations such as
   778 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
   779 isatool doc ref);
   780 
   781 * improved isatool install: option -k creates KDE application icon,
   782 option -p DIR installs standalone binaries;
   783 
   784 * added ML_PLATFORM setting (useful for cross-platform installations);
   785 more robust handling of platform specific ML images for SML/NJ;
   786 
   787 * the settings environment is now statically scoped, i.e. it is never
   788 created again in sub-processes invoked from isabelle, isatool, or
   789 Isabelle;
   790 
   791 * path element specification '~~' refers to '$ISABELLE_HOME';
   792 
   793 * in locales, the "assumes" and "defines" parts may be omitted if
   794 empty;
   795 
   796 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   797 long arrows);
   798 
   799 * new print_mode "HTML";
   800 
   801 * new flag show_tags controls display of tags of theorems (which are
   802 basically just comments that may be attached by some tools);
   803 
   804 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   805 mode and goal output format:
   806 
   807 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   808 244c244
   809 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   810 ---
   811 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   812 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   813 181c181
   814 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   815 ---
   816 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   817 
   818 * function bind_thms stores lists of theorems (cf. bind_thm);
   819 
   820 * new shorthand tactics ftac, eatac, datac, fatac;
   821 
   822 * qed (and friends) now accept "" as result name; in that case the
   823 theorem is not stored, but proper checks and presentation of the
   824 result still apply;
   825 
   826 * theorem database now also indexes constants "Trueprop", "all",
   827 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   828 
   829 
   830 *** HOL ***
   831 
   832 ** HOL arithmetic **
   833 
   834 * There are now decision procedures for linear arithmetic over nat and
   835 int:
   836 
   837 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   838 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   839 are treated as atomic; subformulae not involving type `nat' or `int'
   840 are ignored; quantified subformulae are ignored unless they are
   841 positive universal or negative existential. The tactic has to be
   842 invoked by hand and can be a little bit slow. In particular, the
   843 running time is exponential in the number of occurrences of `min' and
   844 `max', and `-' on `nat'.
   845 
   846 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   847 (negated) (in)equalities among the premises and the conclusion into
   848 account (i.e. no compound formulae) and does not know about `min' and
   849 `max', and `-' on `nat'. It is fast and is used automatically by the
   850 simplifier.
   851 
   852 NB: At the moment, these decision procedures do not cope with mixed
   853 nat/int formulae where the two parts interact, such as `m < n ==>
   854 int(m) < int(n)'.
   855 
   856 * HOL/Numeral provides a generic theory of numerals (encoded
   857 efficiently as bit strings); setup for types nat/int/real is in place;
   858 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   859 int, existing theories and proof scripts may require a few additional
   860 type constraints;
   861 
   862 * integer division and remainder can now be performed on constant
   863 arguments;
   864 
   865 * many properties of integer multiplication, division and remainder
   866 are now available;
   867 
   868 * An interface to the Stanford Validity Checker (SVC) is available through the
   869 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   870 are proved automatically.  SVC must be installed separately, and its results
   871 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   872 invocation of the underlying oracle).  For SVC see
   873   http://verify.stanford.edu/SVC
   874 
   875 * IsaMakefile: the HOL-Real target now builds an actual image;
   876 
   877 
   878 ** HOL misc **
   879 
   880 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   881 (in Isabelle/Isar) -- by Gertrud Bauer;
   882 
   883 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   884 analysis for assembly languages with subtypes;
   885 
   886 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   887 -- avoids syntactic ambiguities and treats state, transition, and
   888 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   889 changed syntax and (many) tactics;
   890 
   891 * HOL/inductive: Now also handles more general introduction rules such
   892   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
   893   theorems are now maintained within the theory (maintained via the
   894   "mono" attribute);
   895 
   896 * HOL/datatype: Now also handles arbitrarily branching datatypes
   897   (using function types) such as
   898 
   899   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
   900 
   901 * HOL/record: record_simproc (part of the default simpset) takes care
   902 of selectors applied to updated records; record_split_tac is no longer
   903 part of the default claset; update_defs may now be removed from the
   904 simpset in many cases; COMPATIBILITY: old behavior achieved by
   905 
   906   claset_ref () := claset() addSWrapper record_split_wrapper;
   907   Delsimprocs [record_simproc]
   908 
   909 * HOL/typedef: fixed type inference for representing set; type
   910 arguments now have to occur explicitly on the rhs as type constraints;
   911 
   912 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
   913 names rather than an ML expression;
   914 
   915 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
   916 supplied later.  Program schemes can be defined, such as
   917     "While B C s = (if B s then While B C (C s) else s)"
   918 where the well-founded relation can be chosen after B and C have been given.
   919 
   920 * HOL/List: the constructors of type list are now Nil and Cons;
   921 INCOMPATIBILITY: while [] and infix # syntax is still there, of
   922 course, ML tools referring to List.list.op # etc. have to be adapted;
   923 
   924 * HOL_quantifiers flag superseded by "HOL" print mode, which is
   925 disabled by default; run isabelle with option -m HOL to get back to
   926 the original Gordon/HOL-style output;
   927 
   928 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
   929 ALL x<=y. P, EX x<y. P, EX x<=y. P;
   930 
   931 * HOL basic syntax simplified (more orthogonal): all variants of
   932 All/Ex now support plain / symbolic / HOL notation; plain syntax for
   933 Eps operator is provided as well: "SOME x. P[x]";
   934 
   935 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
   936 
   937 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
   938 thus available for user theories;
   939 
   940 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
   941 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
   942 time;
   943 
   944 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
   945 several times and then mp;
   946 
   947 
   948 *** LK ***
   949 
   950 * the notation <<...>> is now available as a notation for sequences of
   951 formulas;
   952 
   953 * the simplifier is now installed
   954 
   955 * the axiom system has been generalized (thanks to Soren Heilmann)
   956 
   957 * the classical reasoner now has a default rule database
   958 
   959 
   960 *** ZF ***
   961 
   962 * new primrec section allows primitive recursive functions to be given
   963 directly (as in HOL) over datatypes and the natural numbers;
   964 
   965 * new tactics induct_tac and exhaust_tac for induction (or case
   966 analysis) over datatypes and the natural numbers;
   967 
   968 * the datatype declaration of type T now defines the recursor T_rec;
   969 
   970 * simplification automatically does freeness reasoning for datatype
   971 constructors;
   972 
   973 * automatic type-inference, with AddTCs command to insert new
   974 type-checking rules;
   975 
   976 * datatype introduction rules are now added as Safe Introduction rules
   977 to the claset;
   978 
   979 * the syntax "if P then x else y" is now available in addition to
   980 if(P,x,y);
   981 
   982 
   983 *** Internal programming interfaces ***
   984 
   985 * tuned simplifier trace output; new flag debug_simp;
   986 
   987 * structures Vartab / Termtab (instances of TableFun) offer efficient
   988 tables indexed by indexname_ord / term_ord (compatible with aconv);
   989 
   990 * AxClass.axclass_tac lost the theory argument;
   991 
   992 * tuned current_goals_markers semantics: begin / end goal avoids
   993 printing empty lines;
   994 
   995 * removed prs and prs_fn hook, which was broken because it did not
   996 include \n in its semantics, forcing writeln to add one
   997 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
   998 string -> unit if you really want to output text without newline;
   999 
  1000 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1001 plain output, interface builders may have to enable 'isabelle_font'
  1002 mode to get Isabelle font glyphs as before;
  1003 
  1004 * refined token_translation interface; INCOMPATIBILITY: output length
  1005 now of type real instead of int;
  1006 
  1007 * theory loader actions may be traced via new ThyInfo.add_hook
  1008 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1009 your own database of information attached to *whole* theories -- as
  1010 opposed to intra-theory data slots offered via TheoryDataFun;
  1011 
  1012 * proper handling of dangling sort hypotheses (at last!);
  1013 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1014 extra sort hypotheses that can be witnessed from the type signature;
  1015 the force_strip_shyps flag is gone, any remaining shyps are simply
  1016 left in the theorem (with a warning issued by strip_shyps_warning);
  1017 
  1018 
  1019 
  1020 New in Isabelle98-1 (October 1998)
  1021 ----------------------------------
  1022 
  1023 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1024 
  1025 * several changes of automated proof tools;
  1026 
  1027 * HOL: major changes to the inductive and datatype packages, including
  1028 some minor incompatibilities of theory syntax;
  1029 
  1030 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1031 called `inj_on';
  1032 
  1033 * HOL: removed duplicate thms in Arith:
  1034   less_imp_add_less  should be replaced by  trans_less_add1
  1035   le_imp_add_le      should be replaced by  trans_le_add1
  1036 
  1037 * HOL: unary minus is now overloaded (new type constraints may be
  1038 required);
  1039 
  1040 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1041 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1042 now taken as an integer constant.
  1043 
  1044 * Pure: ML function 'theory_of' renamed to 'theory';
  1045 
  1046 
  1047 *** Proof tools ***
  1048 
  1049 * Simplifier:
  1050   1. Asm_full_simp_tac is now more aggressive.
  1051      1. It will sometimes reorient premises if that increases their power to
  1052         simplify.
  1053      2. It does no longer proceed strictly from left to right but may also
  1054         rotate premises to achieve further simplification.
  1055      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1056      old Asm_full_simp_tac in that it does not rotate premises.
  1057   2. The simplifier now knows a little bit about nat-arithmetic.
  1058 
  1059 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1060 allows for selected deletion of wrappers, by introduction of names for
  1061 wrapper functionals.  This implies that addbefore, addSbefore,
  1062 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1063 and that adding two tactics with the same name overwrites the first
  1064 one (emitting a warning).
  1065   type wrapper = (int -> tactic) -> (int -> tactic)
  1066   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1067   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1068   delWrapper, delSWrapper: claset *  string            -> claset
  1069   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1070 
  1071 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1072 semantics; addbefore now affects only the unsafe part of step_tac
  1073 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1074 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1075 by Force_tac;
  1076 
  1077 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1078 compWrapper; added safe wrapper (and access functions for it);
  1079 
  1080 * HOL/split_all_tac is now much faster and fails if there is nothing
  1081 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1082 and the names of the automatically generated variables have changed.
  1083 split_all_tac has moved within claset() from unsafe wrappers to safe
  1084 wrappers, which means that !!-bound variables are split much more
  1085 aggressively, and safe_tac and clarify_tac now split such variables.
  1086 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1087 Note: the same holds for record_split_tac, which does the job of
  1088 split_all_tac for record fields.
  1089 
  1090 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1091 permanently to the default simpset using Addsplits just like
  1092 Addsimps. They can be removed via Delsplits just like
  1093 Delsimps. Lower-case versions are also available.
  1094 
  1095 * HOL/Simplifier: The rule split_if is now part of the default
  1096 simpset. This means that the simplifier will eliminate all occurrences
  1097 of if-then-else in the conclusion of a goal. To prevent this, you can
  1098 either remove split_if completely from the default simpset by
  1099 `Delsplits [split_if]' or remove it in a specific call of the
  1100 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1101 other case splitting rules to/from the default simpset: every datatype
  1102 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1103 t is the name of the datatype).
  1104 
  1105 * Classical reasoner / Simplifier combination: new force_tac (and
  1106 derivatives Force_tac, force) combines rewriting and classical
  1107 reasoning (and whatever other tools) similarly to auto_tac, but is
  1108 aimed to solve the given subgoal completely.
  1109 
  1110 
  1111 *** General ***
  1112 
  1113 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1114 and `goalw': the theory is no longer needed as an explicit argument -
  1115 the current theory context is used; assumptions are no longer returned
  1116 at the ML-level unless one of them starts with ==> or !!; it is
  1117 recommended to convert to these new commands using isatool fixgoal
  1118 (backup your sources first!);
  1119 
  1120 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1121 the current theory context, and 'theory' to lookup stored theories;
  1122 
  1123 * new theory section 'locale' for declaring constants, assumptions and
  1124 definitions that have local scope;
  1125 
  1126 * new theory section 'nonterminals' for purely syntactic types;
  1127 
  1128 * new theory section 'setup' for generic ML setup functions
  1129 (e.g. package initialization);
  1130 
  1131 * the distribution now includes Isabelle icons: see
  1132 lib/logo/isabelle-{small,tiny}.xpm;
  1133 
  1134 * isatool install - install binaries with absolute references to
  1135 ISABELLE_HOME/bin;
  1136 
  1137 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1138 
  1139 * print mode 'emacs' reserved for Isamode;
  1140 
  1141 * support multiple print (ast) translations per constant name;
  1142 
  1143 * theorems involving oracles are now printed with a suffixed [!];
  1144 
  1145 
  1146 *** HOL ***
  1147 
  1148 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1149 
  1150 * HOL/inductive package reorganized and improved: now supports mutual
  1151 definitions such as
  1152 
  1153   inductive EVEN ODD
  1154     intrs
  1155       null "0 : EVEN"
  1156       oddI "n : EVEN ==> Suc n : ODD"
  1157       evenI "n : ODD ==> Suc n : EVEN"
  1158 
  1159 new theorem list "elims" contains an elimination rule for each of the
  1160 recursive sets; inductive definitions now handle disjunctive premises
  1161 correctly (also ZF);
  1162 
  1163 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1164 "mutual_induct" no longer exists - the induction rule is always
  1165 contained in "induct";
  1166 
  1167 
  1168 * HOL/datatype package re-implemented and greatly improved: now
  1169 supports mutually recursive datatypes such as
  1170 
  1171   datatype
  1172     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1173             | SUM ('a aexp) ('a aexp)
  1174             | DIFF ('a aexp) ('a aexp)
  1175             | NUM 'a
  1176   and
  1177     'a bexp = LESS ('a aexp) ('a aexp)
  1178             | AND ('a bexp) ('a bexp)
  1179             | OR ('a bexp) ('a bexp)
  1180 
  1181 as well as indirectly recursive datatypes such as
  1182 
  1183   datatype
  1184     ('a, 'b) term = Var 'a
  1185                   | App 'b ((('a, 'b) term) list)
  1186 
  1187 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1188 induction on mutually / indirectly recursive datatypes.
  1189 
  1190 Primrec equations are now stored in theory and can be accessed via
  1191 <function_name>.simps.
  1192 
  1193 INCOMPATIBILITIES:
  1194 
  1195   - Theories using datatypes must now have theory Datatype as an
  1196     ancestor.
  1197   - The specific <typename>.induct_tac no longer exists - use the
  1198     generic induct_tac instead.
  1199   - natE has been renamed to nat.exhaust - use exhaust_tac
  1200     instead of res_inst_tac ... natE. Note that the variable
  1201     names in nat.exhaust differ from the names in natE, this
  1202     may cause some "fragile" proofs to fail.
  1203   - The theorems split_<typename>_case and split_<typename>_case_asm
  1204     have been renamed to <typename>.split and <typename>.split_asm.
  1205   - Since default sorts of type variables are now handled correctly,
  1206     some datatype definitions may have to be annotated with explicit
  1207     sort constraints.
  1208   - Primrec definitions no longer require function name and type
  1209     of recursive argument.
  1210 
  1211 Consider using isatool fixdatatype to adapt your theories and proof
  1212 scripts to the new package (backup your sources first!).
  1213 
  1214 
  1215 * HOL/record package: considerably improved implementation; now
  1216 includes concrete syntax for record types, terms, updates; theorems
  1217 for surjective pairing and splitting !!-bound record variables; proof
  1218 support is as follows:
  1219 
  1220   1) standard conversions (selectors or updates applied to record
  1221 constructor terms) are part of the standard simpset;
  1222 
  1223   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1224 made part of standard simpset and claset via addIffs;
  1225 
  1226   3) a tactic for record field splitting (record_split_tac) is part of
  1227 the standard claset (addSWrapper);
  1228 
  1229 To get a better idea about these rules you may retrieve them via
  1230 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1231 the name of your record type.
  1232 
  1233 The split tactic 3) conceptually simplifies by the following rule:
  1234 
  1235   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1236 
  1237 Thus any record variable that is bound by meta-all will automatically
  1238 blow up into some record constructor term, consequently the
  1239 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1240 solve record problems automatically.
  1241 
  1242 
  1243 * reorganized the main HOL image: HOL/Integ and String loaded by
  1244 default; theory Main includes everything;
  1245 
  1246 * automatic simplification of integer sums and comparisons, using cancellation;
  1247 
  1248 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1249 
  1250 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1251 
  1252 * many new identities for unions, intersections, set difference, etc.;
  1253 
  1254 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1255 called split_if, split_split, split_sum_case and split_nat_case (to go
  1256 with add/delsplits);
  1257 
  1258 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1259 (?x::unit) = (); this is made part of the default simpset, which COULD
  1260 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1261 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1262 unit_abs_eta_conv is added in order to counter the effect of
  1263 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1264 %u.f();
  1265 
  1266 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1267 makes more sense);
  1268 
  1269 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1270   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1271   disjointness reasoning but breaking a few old proofs.
  1272 
  1273 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1274 to 'converse' from 'inverse' (for compatibility with ZF and some
  1275 literature);
  1276 
  1277 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1278 the well-founded relation;
  1279 
  1280 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1281     Compl A.  The "Compl" syntax remains available as input syntax for this
  1282     release ONLY.
  1283 
  1284 * HOL/Update: new theory of function updates:
  1285     f(a:=b) == %x. if x=a then b else f x
  1286 may also be iterated as in f(a:=b,c:=d,...);
  1287 
  1288 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1289 
  1290 * HOL/List:
  1291   - new function list_update written xs[i:=v] that updates the i-th
  1292     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1293   - new function `upt' written [i..j(] which generates the list
  1294     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1295     bound write [i..j], which is a shorthand for [i..j+1(].
  1296   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1297 
  1298 * HOL/Arith:
  1299   - removed 'pred' (predecessor) function;
  1300   - generalized some theorems about n-1;
  1301   - many new laws about "div" and "mod";
  1302   - new laws about greatest common divisors (see theory ex/Primes);
  1303 
  1304 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1305 instead of "inverse";
  1306 
  1307 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1308   of the multiset ordering;
  1309 
  1310 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1311   (not included by default);
  1312 
  1313 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1314 
  1315 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1316   programs, i.e. different program variables may have different types.
  1317 
  1318 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1319   [previously, this check worked only if the rewrite rule was unconditional]
  1320   Now rew can involve either definitions or equalities (either == or =).
  1321 
  1322 
  1323 *** ZF ***
  1324 
  1325 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1326   only the theorems proved on ZF.ML;
  1327 
  1328 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1329   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1330   disjointness reasoning but breaking a few old proofs.
  1331 
  1332 * ZF/Update: new theory of function updates
  1333     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1334   may also be iterated as in f(a:=b,c:=d,...);
  1335 
  1336 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1337 
  1338 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1339   [previously, this check worked only if the rewrite rule was unconditional]
  1340   Now rew can involve either definitions or equalities (either == or =).
  1341 
  1342 * case_tac provided for compatibility with HOL
  1343     (like the old excluded_middle_tac, but with subgoals swapped)
  1344 
  1345 
  1346 *** Internal programming interfaces ***
  1347 
  1348 * Pure: several new basic modules made available for general use, see
  1349 also src/Pure/README;
  1350 
  1351 * improved the theory data mechanism to support encapsulation (data
  1352 kind name replaced by private Object.kind, acting as authorization
  1353 key); new type-safe user interface via functor TheoryDataFun; generic
  1354 print_data function becomes basically useless;
  1355 
  1356 * removed global_names compatibility flag -- all theory declarations
  1357 are qualified by default;
  1358 
  1359 * module Pure/Syntax now offers quote / antiquote translation
  1360 functions (useful for Hoare logic etc. with implicit dependencies);
  1361 see HOL/ex/Antiquote for an example use;
  1362 
  1363 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1364 cterm -> thm;
  1365 
  1366 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1367 subgoal;
  1368 
  1369 * Display.print_goals function moved to Locale.print_goals;
  1370 
  1371 * standard print function for goals supports current_goals_markers
  1372 variable for marking begin of proof, end of proof, start of goal; the
  1373 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1374 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1375 for example;
  1376 
  1377 
  1378 
  1379 New in Isabelle98 (January 1998)
  1380 --------------------------------
  1381 
  1382 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1383 
  1384 * changed lexical syntax of terms / types: dots made part of long
  1385 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1386 
  1387 * simpset (and claset) reference variable replaced by functions
  1388 simpset / simpset_ref;
  1389 
  1390 * no longer supports theory aliases (via merge) and non-trivial
  1391 implicit merge of thms' signatures;
  1392 
  1393 * most internal names of constants changed due to qualified names;
  1394 
  1395 * changed Pure/Sequence interface (see Pure/seq.ML);
  1396 
  1397 
  1398 *** General Changes ***
  1399 
  1400 * hierachically structured name spaces (for consts, types, axms, thms
  1401 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1402 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1403 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1404 long_names for fully qualified output names; NOTE: ML programs
  1405 (special tactics, packages etc.) referring to internal names may have
  1406 to be adapted to cope with fully qualified names; in case of severe
  1407 backward campatibility problems try setting 'global_names' at compile
  1408 time to have enrything declared within a flat name space; one may also
  1409 fine tune name declarations in theories via the 'global' and 'local'
  1410 section;
  1411 
  1412 * reimplemented the implicit simpset and claset using the new anytype
  1413 data filed in signatures; references simpset:simpset ref etc. are
  1414 replaced by functions simpset:unit->simpset and
  1415 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1416 to patch your ML files accordingly;
  1417 
  1418 * HTML output now includes theory graph data for display with Java
  1419 applet or isatool browser; data generated automatically via isatool
  1420 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1421 
  1422 * defs may now be conditional; improved rewrite_goals_tac to handle
  1423 conditional equations;
  1424 
  1425 * defs now admits additional type arguments, using TYPE('a) syntax;
  1426 
  1427 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1428 creates a new theory node; implicit merge of thms' signatures is
  1429 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1430 transfer:theory->thm->thm in (rare) cases;
  1431 
  1432 * improved handling of draft signatures / theories; draft thms (and
  1433 ctyps, cterms) are automatically promoted to real ones;
  1434 
  1435 * slightly changed interfaces for oracles: admit many per theory, named
  1436 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1437 
  1438 * print_goals: optional output of const types (set show_consts and
  1439 show_types);
  1440 
  1441 * improved output of warnings (###) and errors (***);
  1442 
  1443 * subgoal_tac displays a warning if the new subgoal has type variables;
  1444 
  1445 * removed old README and Makefiles;
  1446 
  1447 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1448 
  1449 * removed obsolete init_pps and init_database;
  1450 
  1451 * deleted the obsolete tactical STATE, which was declared by
  1452     fun STATE tacfun st = tacfun st st;
  1453 
  1454 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1455 (which abbreviates $HOME);
  1456 
  1457 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1458 use isatool fixseq to adapt your ML programs (this works for fully
  1459 qualified references to the Sequence structure only!);
  1460 
  1461 * use_thy no longer requires writable current directory; it always
  1462 reloads .ML *and* .thy file, if either one is out of date;
  1463 
  1464 
  1465 *** Classical Reasoner ***
  1466 
  1467 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1468 tactics that use classical reasoning to simplify a subgoal without
  1469 splitting it into several subgoals;
  1470 
  1471 * Safe_tac: like safe_tac but uses the default claset;
  1472 
  1473 
  1474 *** Simplifier ***
  1475 
  1476 * added simplification meta rules:
  1477     (asm_)(full_)simplify: simpset -> thm -> thm;
  1478 
  1479 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1480 logics (again);
  1481 
  1482 * added prems argument to simplification procedures;
  1483 
  1484 * HOL, FOL, ZF: added infix function `addsplits':
  1485   instead of `<simpset> setloop (split_tac <thms>)'
  1486   you can simply write `<simpset> addsplits <thms>'
  1487 
  1488 
  1489 *** Syntax ***
  1490 
  1491 * TYPE('a) syntax for type reflection terms;
  1492 
  1493 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1494 
  1495 * pretty printer: changed order of mixfix annotation preference (again!);
  1496 
  1497 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1498 
  1499 
  1500 *** HOL ***
  1501 
  1502 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1503   with `addloop' of the simplifier to faciliate case splitting in premises.
  1504 
  1505 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1506 
  1507 * HOL/Auth: new protocol proofs including some for the Internet
  1508   protocol TLS;
  1509 
  1510 * HOL/Map: new theory of `maps' a la VDM;
  1511 
  1512 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1513 cancelling out common nat summands from =, <, <= (in)equalities, or
  1514 differences; simplification procedures nat_cancel_factor for
  1515 cancelling common factor from =, <, <= (in)equalities over natural
  1516 sums; nat_cancel contains both kinds of procedures, it is installed by
  1517 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1518 
  1519 * HOL/simplifier: terms of the form
  1520   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1521   are rewritten to
  1522   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1523   and those of the form
  1524   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1525   are rewritten to
  1526   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1527 
  1528 * HOL/datatype
  1529   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1530 
  1531   P(t_case f1 ... fn x) =
  1532      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1533         ...
  1534        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1535      )
  1536 
  1537   and a theorem `split_t_case_asm' of the form
  1538 
  1539   P(t_case f1 ... fn x) =
  1540     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1541         ...
  1542        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1543      )
  1544   which can be added to a simpset via `addsplits'. The existing theorems
  1545   expand_list_case and expand_option_case have been renamed to
  1546   split_list_case and split_option_case.
  1547 
  1548 * HOL/Arithmetic:
  1549   - `pred n' is automatically converted to `n-1'.
  1550     Users are strongly encouraged not to use `pred' any longer,
  1551     because it will disappear altogether at some point.
  1552   - Users are strongly encouraged to write "0 < n" rather than
  1553     "n ~= 0". Theorems and proof tools have been modified towards this
  1554     `standard'.
  1555 
  1556 * HOL/Lists:
  1557   the function "set_of_list" has been renamed "set" (and its theorems too);
  1558   the function "nth" now takes its arguments in the reverse order and
  1559   has acquired the infix notation "!" as in "xs!n".
  1560 
  1561 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1562 
  1563 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1564   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1565 
  1566 * HOL/record: extensible records with schematic structural subtyping
  1567 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1568 still lacks various theorems and concrete record syntax;
  1569 
  1570 
  1571 *** HOLCF ***
  1572 
  1573 * removed "axioms" and "generated by" sections;
  1574 
  1575 * replaced "ops" section by extended "consts" section, which is capable of
  1576   handling the continuous function space "->" directly;
  1577 
  1578 * domain package:
  1579   . proves theorems immediately and stores them in the theory,
  1580   . creates hierachical name space,
  1581   . now uses normal mixfix annotations (instead of cinfix...),
  1582   . minor changes to some names and values (for consistency),
  1583   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1584   . separator between mutual domain defs: changed "," to "and",
  1585   . improved handling of sort constraints;  now they have to
  1586     appear on the left-hand side of the equations only;
  1587 
  1588 * fixed LAM <x,y,zs>.b syntax;
  1589 
  1590 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1591 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1592 
  1593 
  1594 *** FOL and ZF ***
  1595 
  1596 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1597   with `addloop' of the simplifier to faciliate case splitting in premises.
  1598 
  1599 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1600 in HOL, they strip ALL and --> from proved theorems;
  1601 
  1602 
  1603 
  1604 New in Isabelle94-8 (May 1997)
  1605 ------------------------------
  1606 
  1607 *** General Changes ***
  1608 
  1609 * new utilities to build / run / maintain Isabelle etc. (in parts
  1610 still somewhat experimental); old Makefiles etc. still functional;
  1611 
  1612 * new 'Isabelle System Manual';
  1613 
  1614 * INSTALL text, together with ./configure and ./build scripts;
  1615 
  1616 * reimplemented type inference for greater efficiency, better error
  1617 messages and clean internal interface;
  1618 
  1619 * prlim command for dealing with lots of subgoals (an easier way of
  1620 setting goals_limit);
  1621 
  1622 
  1623 *** Syntax ***
  1624 
  1625 * supports alternative (named) syntax tables (parser and pretty
  1626 printer); internal interface is provided by add_modesyntax(_i);
  1627 
  1628 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1629 be used in conjunction with the Isabelle symbol font; uses the
  1630 "symbols" syntax table;
  1631 
  1632 * added token_translation interface (may translate name tokens in
  1633 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1634 the current print_mode); IMPORTANT: user print translation functions
  1635 are responsible for marking newly introduced bounds
  1636 (Syntax.mark_boundT);
  1637 
  1638 * token translations for modes "xterm" and "xterm_color" that display
  1639 names in bold, underline etc. or colors (which requires a color
  1640 version of xterm);
  1641 
  1642 * infixes may now be declared with names independent of their syntax;
  1643 
  1644 * added typed_print_translation (like print_translation, but may
  1645 access type of constant);
  1646 
  1647 
  1648 *** Classical Reasoner ***
  1649 
  1650 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  1651 some limitations.  Blast_tac...
  1652   + ignores addss, addbefore, addafter; this restriction is intrinsic
  1653   + ignores elimination rules that don't have the correct format
  1654         (the conclusion MUST be a formula variable)
  1655   + ignores types, which can make HOL proofs fail
  1656   + rules must not require higher-order unification, e.g. apply_type in ZF
  1657     [message "Function Var's argument not a bound variable" relates to this]
  1658   + its proof strategy is more general but can actually be slower
  1659 
  1660 * substitution with equality assumptions no longer permutes other
  1661 assumptions;
  1662 
  1663 * minor changes in semantics of addafter (now called addaltern); renamed
  1664 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  1665 (and access functions for it);
  1666 
  1667 * improved combination of classical reasoner and simplifier:
  1668   + functions for handling clasimpsets
  1669   + improvement of addss: now the simplifier is called _after_ the
  1670     safe steps.
  1671   + safe variant of addss called addSss: uses safe simplifications
  1672     _during_ the safe steps. It is more complete as it allows multiple
  1673     instantiations of unknowns (e.g. with slow_tac).
  1674 
  1675 *** Simplifier ***
  1676 
  1677 * added interface for simplification procedures (functions that
  1678 produce *proven* rewrite rules on the fly, depending on current
  1679 redex);
  1680 
  1681 * ordering on terms as parameter (used for ordered rewriting);
  1682 
  1683 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  1684 
  1685 * the solver is now split into a safe and an unsafe part.
  1686 This should be invisible for the normal user, except that the
  1687 functions setsolver and addsolver have been renamed to setSolver and
  1688 addSolver; added safe_asm_full_simp_tac;
  1689 
  1690 
  1691 *** HOL ***
  1692 
  1693 * a generic induction tactic `induct_tac' which works for all datatypes and
  1694 also for type `nat';
  1695 
  1696 * a generic case distinction tactic `exhaust_tac' which works for all
  1697 datatypes and also for type `nat';
  1698 
  1699 * each datatype comes with a function `size';
  1700 
  1701 * patterns in case expressions allow tuple patterns as arguments to
  1702 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1703 
  1704 * primrec now also works with type nat;
  1705 
  1706 * recdef: a new declaration form, allows general recursive functions to be
  1707 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1708 
  1709 * the constant for negation has been renamed from "not" to "Not" to
  1710 harmonize with FOL, ZF, LK, etc.;
  1711 
  1712 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1713 infinite lists;
  1714 
  1715 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1716 
  1717 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1718 problems in commutative rings, using axiomatic type classes for + and *;
  1719 
  1720 * more examples in HOL/MiniML and HOL/Auth;
  1721 
  1722 * more default rewrite rules for quantifiers, union/intersection;
  1723 
  1724 * a new constant `arbitrary == @x.False';
  1725 
  1726 * HOLCF/IOA replaces old HOL/IOA;
  1727 
  1728 * HOLCF changes: derived all rules and arities
  1729   + axiomatic type classes instead of classes
  1730   + typedef instead of faking type definitions
  1731   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1732   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1733   + eliminated the types void, one, tr
  1734   + use unit lift and bool lift (with translations) instead of one and tr
  1735   + eliminated blift from Lift3.thy (use Def instead of blift)
  1736   all eliminated rules are derived as theorems --> no visible changes ;
  1737 
  1738 
  1739 *** ZF ***
  1740 
  1741 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1742 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1743 as ZF_cs addSIs [equalityI];
  1744 
  1745 
  1746 
  1747 New in Isabelle94-7 (November 96)
  1748 ---------------------------------
  1749 
  1750 * allowing negative levels (as offsets) in prlev and choplev;
  1751 
  1752 * super-linear speedup for large simplifications;
  1753 
  1754 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1755 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1756 FAIL); can suppress it using the command Delsimps (ex_simps @
  1757 all_simps); De Morgan laws are also now included, by default;
  1758 
  1759 * improved printing of ==>  :  ~:
  1760 
  1761 * new object-logic "Sequents" adds linear logic, while replacing LK
  1762 and Modal (thanks to Sara Kalvala);
  1763 
  1764 * HOL/Auth: correctness proofs for authentication protocols;
  1765 
  1766 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1767 examples on HOL/Auth);
  1768 
  1769 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1770 the rewriter and classical reasoner simultaneously;
  1771 
  1772 * function uresult no longer returns theorems in "standard" format;
  1773 regain previous version by: val uresult = standard o uresult;
  1774 
  1775 
  1776 
  1777 New in Isabelle94-6
  1778 -------------------
  1779 
  1780 * oracles -- these establish an interface between Isabelle and trusted
  1781 external reasoners, which may deliver results as theorems;
  1782 
  1783 * proof objects (in particular record all uses of oracles);
  1784 
  1785 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1786 
  1787 * "constdefs" section in theory files;
  1788 
  1789 * "primrec" section (HOL) no longer requires names;
  1790 
  1791 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1792 
  1793 
  1794 
  1795 New in Isabelle94-5
  1796 -------------------
  1797 
  1798 * reduced space requirements;
  1799 
  1800 * automatic HTML generation from theories;
  1801 
  1802 * theory files no longer require "..." (quotes) around most types;
  1803 
  1804 * new examples, including two proofs of the Church-Rosser theorem;
  1805 
  1806 * non-curried (1994) version of HOL is no longer distributed;
  1807 
  1808 
  1809 
  1810 New in Isabelle94-4
  1811 -------------------
  1812 
  1813 * greatly reduced space requirements;
  1814 
  1815 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1816 
  1817 * searchable theorem database (see the section "Retrieving theorems" on
  1818 page 8 of the Reference Manual);
  1819 
  1820 * new examples, including Grabczewski's monumental case study of the
  1821 Axiom of Choice;
  1822 
  1823 * The previous version of HOL renamed to Old_HOL;
  1824 
  1825 * The new version of HOL (previously called CHOL) uses a curried syntax
  1826 for functions.  Application looks like f a b instead of f(a,b);
  1827 
  1828 * Mutually recursive inductive definitions finally work in HOL;
  1829 
  1830 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1831 translates to the operator "split";
  1832 
  1833 
  1834 
  1835 New in Isabelle94-3
  1836 -------------------
  1837 
  1838 * new infix operator, addss, allowing the classical reasoner to
  1839 perform simplification at each step of its search.  Example:
  1840         fast_tac (cs addss ss)
  1841 
  1842 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1843 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1844 look like (a,b) instead of <a,b>;
  1845 
  1846 * PLEASE NOTE: CHOL will eventually replace HOL!
  1847 
  1848 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1849 It translates to the operator "split".  A new theory of integers is available;
  1850 
  1851 * In ZF, integer numerals now denote two's-complement binary integers.
  1852 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1853 
  1854 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1855 of the Axiom of Choice;
  1856 
  1857 
  1858 
  1859 New in Isabelle94-2
  1860 -------------------
  1861 
  1862 * Significantly faster resolution;
  1863 
  1864 * the different sections in a .thy file can now be mixed and repeated
  1865 freely;
  1866 
  1867 * Database of theorems for FOL, HOL and ZF.  New
  1868 commands including qed, qed_goal and bind_thm store theorems in the database.
  1869 
  1870 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1871 a given theory (thms_of), or find out what theory a theorem was proved in
  1872 (theory_of_thm);
  1873 
  1874 * Bugs fixed in the inductive definition and datatype packages;
  1875 
  1876 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1877 and HOL_dup_cs obsolete;
  1878 
  1879 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1880 have been removed;
  1881 
  1882 * Simpler definition of function space in ZF;
  1883 
  1884 * new results about cardinal and ordinal arithmetic in ZF;
  1885 
  1886 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1887 types;
  1888 
  1889 
  1890 $Id$