NEWS
author wenzelm
Wed Oct 31 01:27:04 2001 +0100 (2001-10-31)
changeset 11995 4a622f5fb164
parent 11986 26b95a6f3f79
child 12022 9c3377b133c0
permissions -rw-r--r--
- 'induct' may now use elim-style induction rules without chaining
facts, using ``missing'' premises from the goal state; this allows
rules stemming from inductive sets to be applied in unstructured
scripts, while still benefitting from proper handling of non-atomic
statements; NB: major inductive premises need to be put first, all the
rest of the goal is passed through the induction;
     1 
     2 Isabelle NEWS -- history user-relevant changes
     3 ==============================================
     4 
     5 New in Isabelle2001 (?? 2001)
     6 -----------------------------
     7 
     8 *** Document preparation ***
     9 
    10 * greatly simplified document preparation setup, including more
    11 graceful interpretation of isatool usedir -i/-d/-D options, and more
    12 instructive isatool mkdir; users should basically be able to get
    13 started with "isatool mkdir Test && isatool make";
    14 
    15 * theory dependency graph may now be incorporated into documents;
    16 isatool usedir -g true will produce session_graph.eps/.pdf for use
    17 with \includegraphics of LaTeX;
    18 
    19 * proper spacing of consecutive markup elements, especially text
    20 blocks after section headings;
    21 
    22 * support bold style (for single symbols only), input syntax is like
    23 this: "\<^bold>\<alpha>" or "\<^bold>A";
    24 
    25 * \<bullet> is now output as bold \cdot by default, which looks much
    26 better in printed text;
    27 
    28 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
    29 note that these symbols are currently unavailable in Proof General /
    30 X-Symbol;
    31 
    32 
    33 *** Isar ***
    34 
    35 * improved proof by cases and induction:
    36   - removed obsolete "(simplified)" and "(stripped)" options of methods;
    37   - added 'print_induct_rules' (covered by help item in Proof General > 3.3);
    38   - moved induct/cases attributes to Pure, methods to Provers;
    39   - generic method setup instantiated for FOL and HOL;
    40 
    41   - 'case' command admits impromptu naming of parameters (such as
    42 "case (Suc n)");
    43 
    44   - 'induct' method divinates rule instantiation from the inductive
    45 claim; no longer requires excessive ?P bindings for proper
    46 instantiation of cases;
    47 
    48   - 'induct' method properly enumerates all possibilities of set/type
    49 rules; as a consequence facts may be also passed through *type* rules
    50 without further ado;
    51 
    52   - 'induct' method now derives symbolic cases from the *rulified*
    53 rule (before it used to rulify cases stemming from the internal
    54 atomized version); this means that the context of a non-atomic
    55 statement becomes is included in the hypothesis, avoiding the slightly
    56 cumbersome show "PROP ?case" form;
    57 
    58   - 'induct' may now use elim-style induction rules without chaining
    59 facts, using ``missing'' premises from the goal state; this allows
    60 rules stemming from inductive sets to be applied in unstructured
    61 scripts, while still benefitting from proper handling of non-atomic
    62 statements; NB: major inductive premises need to be put first, all the
    63 rest of the goal is passed through the induction;
    64 
    65 * Pure: renamed "antecedent" case to "rule_context";
    66 
    67 * Pure: added 'corollary' command;
    68 
    69 * Pure: fixed 'token_translation' command;
    70 
    71 * Pure: removed obsolete 'exported' attribute;
    72 
    73 * Pure: dummy pattern "_" in is/let is now automatically lifted over
    74 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
    75 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
    76 
    77 * Pure: method 'atomize' presents local goal premises as object-level
    78 statements (atomic meta-level propositions); setup controlled via
    79 rewrite rules declarations of 'atomize' attribute; example
    80 application: 'induct' method with proper rule statements in improper
    81 proof *scripts*;
    82 
    83 * Provers: 'simplified' attribute may refer to explicit rules instead
    84 of full simplifier context; 'iff' attribute handles conditional rules;
    85 
    86 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
    87 
    88 * HOL: 'recdef' now fails on unfinished automated proofs, use
    89 "(permissive)" option to recover old behavior;
    90 
    91 * HOL: 'inductive' no longer features separate (collective) attributes
    92 for 'intros' (was found too confusing);
    93 
    94 
    95 
    96 *** HOL ***
    97 
    98 * HOL: moved over to sane numeral syntax; the new policy is as
    99 follows:
   100 
   101   - 0 and 1 are polymorphic constants, which are defined on any
   102   numeric type (nat, int, real etc.);
   103 
   104   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   105   binary representation internally;
   106 
   107   - type nat has special constructor Suc, and generally prefers Suc 0
   108   over 1::nat and Suc (Suc 0) over 2::nat;
   109 
   110 This change may cause significant INCOMPATIBILITIES; here are some
   111 hints on converting existing sources:
   112 
   113   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   114   entities, so expressions involving "-" (unary or binary minus) need
   115   to be spaced properly;
   116 
   117   - existing occurrences of "1" may need to be constraint "1::nat" or
   118   even replaced by Suc 0; similar for old "2";
   119 
   120   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   121 
   122   - remove all special provisions on numerals in proofs;
   123 
   124 * HOL/record:
   125   - removed old "make" and "make_scheme" operations -- INCOMPATIBILITY;
   126   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   127   - provides cases/induct rules for use with corresponding Isar methods;
   128   - new derived operations "make" (for adding fields of current
   129     record), "extend" to promote fixed record to record scheme, and
   130     "truncate" for the reverse; cf. theorems "derived_defs", which are
   131     *not* declared as simp by default;
   132   - internal definitions directly based on a light-weight abstract
   133     theory of product types over typedef rather than datatype;
   134 
   135 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   136 
   137 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   138 (beware of argument permutation!);
   139 
   140 * HOL: linorder_less_split superseded by linorder_cases;
   141 
   142 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   143 to peripheral theory "Hilbert_Choice";
   144 
   145 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   146 in this (rare) case use:
   147 
   148   delSWrapper "split_all_tac"
   149   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   150 
   151 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   152 MAY FAIL;
   153 
   154 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   155 Isabelle's type classes, ^ on functions and relations has too general
   156 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   157 necessary to attach explicit type constraints;
   158 
   159 * HOL: syntax translations now work properly with numerals and records
   160 expressions;
   161 
   162 * HOL/GroupTheory: group theory examples including Sylow's theorem, by
   163 Florian Kammüller;
   164 
   165 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   166 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   167 renamed "Product_Type.unit";
   168 
   169 
   170 *** ZF ***
   171 
   172 * ZF: the integer library now covers quotients and remainders, with
   173 many laws relating division to addition, multiplication, etc.;
   174 
   175 
   176 *** General ***
   177 
   178 * kernel: meta-level proof terms (by Stefan Berghofer), see also ref
   179 manual;
   180 
   181 * Pure/axclass: removed obsolete ML interface goal_subclass/goal_arity;
   182 
   183 * classical: renamed addaltern to addafter, addSaltern to addSafter;
   184 
   185 * clasimp: ``iff'' declarations now handle conditional rules as well;
   186 
   187 * syntax: new token syntax "num" for plain numerals (without "#" of
   188 "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now separate
   189 tokens, so expressions involving minus need to be spaced properly;
   190 
   191 * syntax: support non-oriented infixes;
   192 
   193 * syntax: print modes "type_brackets" and "no_type_brackets" control
   194 output of nested => (types); the default behavior is "type_brackets";
   195 
   196 * syntax: builtin parse translation for "_constify" turns valued
   197 tokens into AST constants;
   198 
   199 * system: support Poly/ML 4.1.1 (now able to manage large heaps);
   200 
   201 * system: Proof General keywords specification is now part of the
   202 Isabelle distribution (see etc/isar-keywords.el);
   203 
   204 * system: smart selection of Isabelle process versus Isabelle
   205 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   206 run both "isabelle" and "Isabelle" even if file names are badly
   207 damaged (executable inspects the case of the first letter of its own
   208 name); added separate "isabelle-process" and "isabelle-interface";
   209 
   210 
   211 
   212 New in Isabelle99-2 (February 2001)
   213 -----------------------------------
   214 
   215 *** Overview of INCOMPATIBILITIES ***
   216 
   217 * HOL: please note that theories in the Library and elsewhere often use the
   218 new-style (Isar) format; to refer to their theorems in an ML script you must
   219 bind them to ML identifers by e.g.	val thm_name = thm "thm_name";
   220 
   221 * HOL: inductive package no longer splits induction rule aggressively,
   222 but only as far as specified by the introductions given; the old
   223 format may be recovered via ML function complete_split_rule or attribute
   224 'split_rule (complete)';
   225 
   226 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   227 gfp_Tarski to gfp_unfold;
   228 
   229 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   230 
   231 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   232 relation); infix "^^" has been renamed "``"; infix "``" has been
   233 renamed "`"; "univalent" has been renamed "single_valued";
   234 
   235 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   236 operation;
   237 
   238 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   239 
   240 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   241 
   242 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   243 consequence, it is no longer monotonic wrt. the local goal context
   244 (which is now passed through the inductive cases);
   245 
   246 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   247 \<gg> to \<ggreater>;
   248 
   249 
   250 *** Document preparation ***
   251 
   252 * \isabellestyle{NAME} selects version of Isabelle output (currently
   253 available: are "it" for near math-mode best-style output, "sl" for
   254 slanted text style, and "tt" for plain type-writer; if no
   255 \isabellestyle command is given, output is according to slanted
   256 type-writer);
   257 
   258 * support sub/super scripts (for single symbols only), input syntax is
   259 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   260 
   261 * some more standard symbols; see Appendix A of the system manual for
   262 the complete list of symbols defined in isabellesym.sty;
   263 
   264 * improved isabelle style files; more abstract symbol implementation
   265 (should now use \isamath{...} and \isatext{...} in custom symbol
   266 definitions);
   267 
   268 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   269 state; Note that presentation of goal states does not conform to
   270 actual human-readable proof documents.  Please do not include goal
   271 states into document output unless you really know what you are doing!
   272 
   273 * proper indentation of antiquoted output with proportional LaTeX
   274 fonts;
   275 
   276 * no_document ML operator temporarily disables LaTeX document
   277 generation;
   278 
   279 * isatool unsymbolize tunes sources for plain ASCII communication;
   280 
   281 
   282 *** Isar ***
   283 
   284 * Pure: Isar now suffers initial goal statements to contain unbound
   285 schematic variables (this does not conform to actual readable proof
   286 documents, due to unpredictable outcome and non-compositional proof
   287 checking); users who know what they are doing may use schematic goals
   288 for Prolog-style synthesis of proven results;
   289 
   290 * Pure: assumption method (an implicit finishing) now handles actual
   291 rules as well;
   292 
   293 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   294 initial goal, declare "that" only as Pure intro (only for single
   295 steps); the "that" rule assumption may now be involved in implicit
   296 finishing, thus ".." becomes a feasible for trivial obtains;
   297 
   298 * Pure: default proof step now includes 'intro_classes'; thus trivial
   299 instance proofs may be performed by "..";
   300 
   301 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   302 statements as well;
   303 
   304 * Pure: more robust selection of calculational rules;
   305 
   306 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   307 rule (as well as the assumption rule);
   308 
   309 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   310 lemmas, using the graph browser tool;
   311 
   312 * Pure: predict failure of "show" in interactive mode;
   313 
   314 * Pure: 'thms_containing' now takes actual terms as arguments;
   315 
   316 * HOL: improved method 'induct' --- now handles non-atomic goals
   317 (potential INCOMPATIBILITY); tuned error handling;
   318 
   319 * HOL: cases and induct rules now provide explicit hints about the
   320 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   321 any remaining facts are inserted into the goal verbatim;
   322 
   323 * HOL: local contexts (aka cases) may now contain term bindings as
   324 well; the 'cases' and 'induct' methods new provide a ?case binding for
   325 the result to be shown in each case;
   326 
   327 * HOL: added 'recdef_tc' command;
   328 
   329 * isatool convert assists in eliminating legacy ML scripts;
   330 
   331 
   332 *** HOL ***
   333 
   334 * HOL/Library: a collection of generic theories to be used together
   335 with main HOL; the theory loader path already includes this directory
   336 by default; the following existing theories have been moved here:
   337 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   338 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   339 
   340 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   341 modelling and verification task performed in Isabelle/HOL +
   342 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   343 
   344 * HOL/Algebra: special summation operator SUM no longer exists, it has
   345 been replaced by setsum; infix 'assoc' now has priority 50 (like
   346 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   347 'domain', this makes the theory consistent with mathematical
   348 literature;
   349 
   350 * HOL basics: added overloaded operations "inverse" and "divide"
   351 (infix "/"), syntax for generic "abs" operation, generic summation
   352 operator \<Sum>;
   353 
   354 * HOL/typedef: simplified package, provide more useful rules (see also
   355 HOL/subset.thy);
   356 
   357 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   358 now expressed as a proper nested rule (old-style tactic scripts may
   359 require atomize_strip_tac to cope with non-atomic premises);
   360 
   361 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   362 to "split_conv" (old name still available for compatibility);
   363 
   364 * HOL: improved concrete syntax for strings (e.g. allows translation
   365 rules with string literals);
   366 
   367 * HOL-Hyperreal: a new target, extending HOL-Real with the hyperreals
   368 and Fleuriot's mechanization of analysis;
   369 
   370 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   371 
   372 
   373 *** CTT ***
   374 
   375 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   376 "lam" is displayed as TWO lambda-symbols
   377 
   378 * CTT: theory Main now available, containing everything (that is, Bool
   379 and Arith);
   380 
   381 
   382 *** General ***
   383 
   384 * Pure: the Simplifier has been implemented properly as a derived rule
   385 outside of the actual kernel (at last!); the overall performance
   386 penalty in practical applications is about 50%, while reliability of
   387 the Isabelle inference kernel has been greatly improved;
   388 
   389 * print modes "brackets" and "no_brackets" control output of nested =>
   390 (types) and ==> (props); the default behaviour is "brackets";
   391 
   392 * Provers: fast_tac (and friends) now handle actual object-logic rules
   393 as assumptions as well;
   394 
   395 * system: support Poly/ML 4.0;
   396 
   397 * system: isatool install handles KDE version 1 or 2;
   398 
   399 
   400 
   401 New in Isabelle99-1 (October 2000)
   402 ----------------------------------
   403 
   404 *** Overview of INCOMPATIBILITIES ***
   405 
   406 * HOL: simplification of natural numbers is much changed; to partly
   407 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   408 issue the following ML commands:
   409 
   410   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   411   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   412 
   413 * HOL: simplification no longer dives into case-expressions; this is
   414 controlled by "t.weak_case_cong" for each datatype t;
   415 
   416 * HOL: nat_less_induct renamed to less_induct;
   417 
   418 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   419 fixsome to patch .thy and .ML sources automatically;
   420 
   421   select_equality  -> some_equality
   422   select_eq_Ex     -> some_eq_ex
   423   selectI2EX       -> someI2_ex
   424   selectI2         -> someI2
   425   selectI          -> someI
   426   select1_equality -> some1_equality
   427   Eps_sym_eq       -> some_sym_eq_trivial
   428   Eps_eq           -> some_eq_trivial
   429 
   430 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   431 
   432 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   433 instead);
   434 
   435 * HOL: the recursion equations generated by 'recdef' are now called
   436 f.simps instead of f.rules;
   437 
   438 * HOL: qed_spec_mp now also handles bounded ALL as well;
   439 
   440 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   441 sometimes be needed;
   442 
   443 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   444 
   445 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   446 
   447 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   448 product is now "<*>" instead of "Times"; the lexicographic product is
   449 now "<*lex*>" instead of "**";
   450 
   451 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   452 of main HOL, but was unused); better use HOL's datatype package;
   453 
   454 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   455 the old syntax may be recovered as follows:
   456 
   457   syntax (symbols)
   458     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   459       (infixl "\\<oplus>" 100)
   460 
   461 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   462 
   463 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   464 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   465 internally;
   466 
   467 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   468 changed from A/r to A//r;
   469 
   470 * ZF: new treatment of arithmetic (nat & int) may break some old
   471 proofs;
   472 
   473 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   474 rulify -> rule_format, elimify -> elim_format, ...);
   475 
   476 * Isar/Provers: intro/elim/dest attributes changed; renamed
   477 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   478 should have to change intro!! to intro? only); replaced "delrule" by
   479 "rule del";
   480 
   481 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   482 
   483 * Provers: strengthened force_tac by using new first_best_tac;
   484 
   485 * LaTeX document preparation: several changes of isabelle.sty (see
   486 lib/texinputs);
   487 
   488 
   489 *** Document preparation ***
   490 
   491 * formal comments (text blocks etc.) in new-style theories may now
   492 contain antiquotations of thm/prop/term/typ/text to be presented
   493 according to latex print mode; concrete syntax is like this:
   494 @{term[show_types] "f(x) = a + x"};
   495 
   496 * isatool mkdir provides easy setup of Isabelle session directories,
   497 including proper document sources;
   498 
   499 * generated LaTeX sources are now deleted after successful run
   500 (isatool document -c); may retain a copy somewhere else via -D option
   501 of isatool usedir;
   502 
   503 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   504 style files, achieving self-contained LaTeX sources and simplifying
   505 LaTeX debugging;
   506 
   507 * old-style theories now produce (crude) LaTeX output as well;
   508 
   509 * browser info session directories are now self-contained (may be put
   510 on WWW server seperately); improved graphs of nested sessions; removed
   511 graph for 'all sessions';
   512 
   513 * several improvements in isabelle style files; \isabellestyle{it}
   514 produces fake math mode output; \isamarkupheader is now \section by
   515 default; see lib/texinputs/isabelle.sty etc.;
   516 
   517 
   518 *** Isar ***
   519 
   520 * Isar/Pure: local results and corresponding term bindings are now
   521 subject to Hindley-Milner polymorphism (similar to ML); this
   522 accommodates incremental type-inference very nicely;
   523 
   524 * Isar/Pure: new derived language element 'obtain' supports
   525 generalized existence reasoning;
   526 
   527 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   528 support accumulation of results, without applying any rules yet;
   529 useful to collect intermediate results without explicit name
   530 references, and for use with transitivity rules with more than 2
   531 premises;
   532 
   533 * Isar/Pure: scalable support for case-analysis type proofs: new
   534 'case' language element refers to local contexts symbolically, as
   535 produced by certain proof methods; internally, case names are attached
   536 to theorems as "tags";
   537 
   538 * Isar/Pure: theory command 'hide' removes declarations from
   539 class/type/const name spaces;
   540 
   541 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   542 indicate potential overloading;
   543 
   544 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   545 
   546 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   547 "{a,b,c}" instead of {a,b,c};
   548 
   549 * Isar/Pure now provides its own version of intro/elim/dest
   550 attributes; useful for building new logics, but beware of confusion
   551 with the version in Provers/classical;
   552 
   553 * Isar/Pure: the local context of (non-atomic) goals is provided via
   554 case name 'antecedent';
   555 
   556 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   557 to the current context is now done automatically);
   558 
   559 * Isar/Pure: theory command 'method_setup' provides a simple interface
   560 for definining proof methods in ML;
   561 
   562 * Isar/Provers: intro/elim/dest attributes changed; renamed
   563 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   564 most cases, one should have to change intro!! to intro? only);
   565 replaced "delrule" by "rule del";
   566 
   567 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   568 'symmetric' attribute (the latter supercedes [RS sym]);
   569 
   570 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   571 method modifier); 'simp' method: 'only:' modifier removes loopers as
   572 well (including splits);
   573 
   574 * Isar/Provers: Simplifier and Classical methods now support all kind
   575 of modifiers used in the past, including 'cong', 'iff', etc.
   576 
   577 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   578 of Simplifier and Classical reasoner);
   579 
   580 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   581 now support named cases; major packages (inductive, datatype, primrec,
   582 recdef) support case names and properly name parameters;
   583 
   584 * Isar/HOL: new transitivity rules for substitution in inequalities --
   585 monotonicity conditions are extracted to be proven at end of
   586 calculations;
   587 
   588 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   589 method anyway;
   590 
   591 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   592 split_if split_if_asm; datatype package provides theorems foo.splits =
   593 foo.split foo.split_asm for each datatype;
   594 
   595 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   596 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   597 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   598 use "(cases (simplified))" method in proper proof texts);
   599 
   600 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   601 
   602 * Isar: names of theorems etc. may be natural numbers as well;
   603 
   604 * Isar: 'pr' command: optional arguments for goals_limit and
   605 ProofContext.prems_limit; no longer prints theory contexts, but only
   606 proof states;
   607 
   608 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   609 additional print modes to be specified; e.g. "pr(latex)" will print
   610 proof state according to the Isabelle LaTeX style;
   611 
   612 * Isar: improved support for emulating tactic scripts, including proof
   613 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   614 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   615 (for HOL datatypes);
   616 
   617 * Isar: simplified (more robust) goal selection of proof methods: 1st
   618 goal, all goals, or explicit goal specifier (tactic emulation); thus
   619 'proof method scripts' have to be in depth-first order;
   620 
   621 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   622 
   623 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   624 should instead use individual commands for printing items
   625 (print_commands, print_methods etc.);
   626 
   627 * Isar: added 'nothing' --- the empty list of theorems;
   628 
   629 
   630 *** HOL ***
   631 
   632 * HOL/MicroJava: formalization of a fragment of Java, together with a
   633 corresponding virtual machine and a specification of its bytecode
   634 verifier and a lightweight bytecode verifier, including proofs of
   635 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   636 Cornelia Pusch (see also the homepage of project Bali at
   637 http://isabelle.in.tum.de/Bali/);
   638 
   639 * HOL/Algebra: new theory of rings and univariate polynomials, by
   640 Clemens Ballarin;
   641 
   642 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   643 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   644 Rasmussen;
   645 
   646 * HOL/Lattice: fundamental concepts of lattice theory and order
   647 structures, including duals, properties of bounds versus algebraic
   648 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   649 Theorem for complete lattices etc.; may also serve as a demonstration
   650 for abstract algebraic reasoning using axiomatic type classes, and
   651 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   652 
   653 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   654 von Oheimb;
   655 
   656 * HOL/IMPP: extension of IMP with local variables and mutually
   657 recursive procedures, by David von Oheimb;
   658 
   659 * HOL/Lambda: converted into new-style theory and document;
   660 
   661 * HOL/ex/Multiquote: example of multiple nested quotations and
   662 anti-quotations -- basically a generalized version of de-Bruijn
   663 representation; very useful in avoiding lifting of operations;
   664 
   665 * HOL/record: added general record equality rule to simpset; fixed
   666 select-update simplification procedure to handle extended records as
   667 well; admit "r" as field name;
   668 
   669 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   670 other numeric types and also as the identity of groups, rings, etc.;
   671 
   672 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   673 Types nat and int belong to this axclass;
   674 
   675 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   676    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   677    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   678   two terms #m*u and #n*u are replaced by #(m+n)*u
   679     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   680   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   681     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   682 
   683 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   684 powerful prover for predicate logic but knows nothing of clasets; see
   685 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   686 
   687 * HOL: new version of "case_tac" subsumes both boolean case split and
   688 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   689 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   690 
   691 * HOL: simplification no longer dives into case-expressions: only the
   692 selector expression is simplified, but not the remaining arms; to
   693 enable full simplification of case-expressions for datatype t, you may
   694 remove t.weak_case_cong from the simpset, either globally (Delcongs
   695 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   696 
   697 * HOL/recdef: the recursion equations generated by 'recdef' for
   698 function 'f' are now called f.simps instead of f.rules; if all
   699 termination conditions are proved automatically, these simplification
   700 rules are added to the simpset, as in primrec; rules may be named
   701 individually as well, resulting in a separate list of theorems for
   702 each equation;
   703 
   704 * HOL/While is a new theory that provides a while-combinator. It
   705 permits the definition of tail-recursive functions without the
   706 provision of a termination measure. The latter is necessary once the
   707 invariant proof rule for while is applied.
   708 
   709 * HOL: new (overloaded) notation for the set of elements below/above
   710 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   711 
   712 * HOL: theorems impI, allI, ballI bound as "strip";
   713 
   714 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   715 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   716 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   717 
   718 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   719 
   720 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   721 main HOL, but was unused);
   722 
   723 * HOL: fewer consts declared as global (e.g. have to refer to
   724 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   725 
   726 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   727 in case of overlap with user translations (e.g. judgements over
   728 tuples); (note that the underlying logical represenation is still
   729 bogus);
   730 
   731 
   732 *** ZF ***
   733 
   734 * ZF: simplification automatically cancels common terms in arithmetic
   735 expressions over nat and int;
   736 
   737 * ZF: new treatment of nat to minimize type-checking: all operators
   738 coerce their operands to a natural number using the function natify,
   739 making the algebraic laws unconditional;
   740 
   741 * ZF: as above, for int: operators coerce their operands to an integer
   742 using the function intify;
   743 
   744 * ZF: the integer library now contains many of the usual laws for the
   745 orderings, including $<=, and monotonicity laws for $+ and $*;
   746 
   747 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
   748 simplification;
   749 
   750 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
   751 to the simplifier and classical reasoner simultaneously;
   752 
   753 
   754 *** General ***
   755 
   756 * Provers: blast_tac now handles actual object-logic rules as
   757 assumptions; note that auto_tac uses blast_tac internally as well;
   758 
   759 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
   760 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
   761 
   762 * Provers: delrules now handles destruct rules as well (no longer need
   763 explicit make_elim);
   764 
   765 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
   766   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   767 use instead the strong form,
   768   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   769 in HOL, FOL and ZF the function cla_make_elim will create such rules
   770 from destruct-rules;
   771 
   772 * Provers: Simplifier.easy_setup provides a fast path to basic
   773 Simplifier setup for new object-logics;
   774 
   775 * Pure: AST translation rules no longer require constant head on LHS;
   776 
   777 * Pure: improved name spaces: ambiguous output is qualified; support
   778 for hiding of names;
   779 
   780 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
   781 XSYMBOL_HOME; no longer need to do manual configuration in most
   782 situations;
   783 
   784 * system: compression of ML heaps images may now be controlled via -c
   785 option of isabelle and isatool usedir (currently only observed by
   786 Poly/ML);
   787 
   788 * system: isatool installfonts may handle X-Symbol fonts as well (very
   789 useful for remote X11);
   790 
   791 * system: provide TAGS file for Isabelle sources;
   792 
   793 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
   794 order;
   795 
   796 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
   797 timing flag supersedes proof_timing and Toplevel.trace;
   798 
   799 * ML: new combinators |>> and |>>> for incremental transformations
   800 with secondary results (e.g. certain theory extensions):
   801 
   802 * ML: PureThy.add_defs gets additional argument to indicate potential
   803 overloading (usually false);
   804 
   805 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
   806 results;
   807 
   808 
   809 
   810 New in Isabelle99 (October 1999)
   811 --------------------------------
   812 
   813 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   814 
   815 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
   816 are no longer simplified.  (This allows the simplifier to unfold recursive
   817 functional programs.)  To restore the old behaviour, declare
   818 
   819     Delcongs [if_weak_cong];
   820 
   821 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
   822 complement;
   823 
   824 * HOL: the predicate "inj" is now defined by translation to "inj_on";
   825 
   826 * HOL/datatype: mutual_induct_tac no longer exists --
   827   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
   828 
   829 * HOL/typedef: fixed type inference for representing set; type
   830 arguments now have to occur explicitly on the rhs as type constraints;
   831 
   832 * ZF: The con_defs part of an inductive definition may no longer refer
   833 to constants declared in the same theory;
   834 
   835 * HOL, ZF: the function mk_cases, generated by the inductive
   836 definition package, has lost an argument.  To simplify its result, it
   837 uses the default simpset instead of a supplied list of theorems.
   838 
   839 * HOL/List: the constructors of type list are now Nil and Cons;
   840 
   841 * Simplifier: the type of the infix ML functions
   842         setSSolver addSSolver setSolver addSolver
   843 is now  simpset * solver -> simpset  where `solver' is a new abstract type
   844 for packaging solvers. A solver is created via
   845         mk_solver: string -> (thm list -> int -> tactic) -> solver
   846 where the string argument is only a comment.
   847 
   848 
   849 *** Proof tools ***
   850 
   851 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
   852 decision procedure for linear arithmetic. Currently it is used for
   853 types `nat', `int', and `real' in HOL (see below); it can, should and
   854 will be instantiated for other types and logics as well.
   855 
   856 * The simplifier now accepts rewrite rules with flexible heads, eg
   857      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
   858   They are applied like any rule with a non-pattern lhs, i.e. by first-order
   859   matching.
   860 
   861 
   862 *** General ***
   863 
   864 * New Isabelle/Isar subsystem provides an alternative to traditional
   865 tactical theorem proving; together with the ProofGeneral/isar user
   866 interface it offers an interactive environment for developing human
   867 readable proof documents (Isar == Intelligible semi-automated
   868 reasoning); for further information see isatool doc isar-ref,
   869 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
   870 
   871 * improved and simplified presentation of theories: better HTML markup
   872 (including colors), graph views in several sizes; isatool usedir now
   873 provides a proper interface for user theories (via -P option); actual
   874 document preparation based on (PDF)LaTeX is available as well (for
   875 new-style theories only); see isatool doc system for more information;
   876 
   877 * native support for Proof General, both for classic Isabelle and
   878 Isabelle/Isar;
   879 
   880 * ML function thm_deps visualizes dependencies of theorems and lemmas,
   881 using the graph browser tool;
   882 
   883 * Isabelle manuals now also available as PDF;
   884 
   885 * theory loader rewritten from scratch (may not be fully
   886 bug-compatible); old loadpath variable has been replaced by show_path,
   887 add_path, del_path, reset_path functions; new operations such as
   888 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
   889 isatool doc ref);
   890 
   891 * improved isatool install: option -k creates KDE application icon,
   892 option -p DIR installs standalone binaries;
   893 
   894 * added ML_PLATFORM setting (useful for cross-platform installations);
   895 more robust handling of platform specific ML images for SML/NJ;
   896 
   897 * the settings environment is now statically scoped, i.e. it is never
   898 created again in sub-processes invoked from isabelle, isatool, or
   899 Isabelle;
   900 
   901 * path element specification '~~' refers to '$ISABELLE_HOME';
   902 
   903 * in locales, the "assumes" and "defines" parts may be omitted if
   904 empty;
   905 
   906 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   907 long arrows);
   908 
   909 * new print_mode "HTML";
   910 
   911 * new flag show_tags controls display of tags of theorems (which are
   912 basically just comments that may be attached by some tools);
   913 
   914 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   915 mode and goal output format:
   916 
   917 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   918 244c244
   919 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   920 ---
   921 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   922 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   923 181c181
   924 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   925 ---
   926 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   927 
   928 * function bind_thms stores lists of theorems (cf. bind_thm);
   929 
   930 * new shorthand tactics ftac, eatac, datac, fatac;
   931 
   932 * qed (and friends) now accept "" as result name; in that case the
   933 theorem is not stored, but proper checks and presentation of the
   934 result still apply;
   935 
   936 * theorem database now also indexes constants "Trueprop", "all",
   937 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   938 
   939 
   940 *** HOL ***
   941 
   942 ** HOL arithmetic **
   943 
   944 * There are now decision procedures for linear arithmetic over nat and
   945 int:
   946 
   947 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   948 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   949 are treated as atomic; subformulae not involving type `nat' or `int'
   950 are ignored; quantified subformulae are ignored unless they are
   951 positive universal or negative existential. The tactic has to be
   952 invoked by hand and can be a little bit slow. In particular, the
   953 running time is exponential in the number of occurrences of `min' and
   954 `max', and `-' on `nat'.
   955 
   956 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   957 (negated) (in)equalities among the premises and the conclusion into
   958 account (i.e. no compound formulae) and does not know about `min' and
   959 `max', and `-' on `nat'. It is fast and is used automatically by the
   960 simplifier.
   961 
   962 NB: At the moment, these decision procedures do not cope with mixed
   963 nat/int formulae where the two parts interact, such as `m < n ==>
   964 int(m) < int(n)'.
   965 
   966 * HOL/Numeral provides a generic theory of numerals (encoded
   967 efficiently as bit strings); setup for types nat/int/real is in place;
   968 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   969 int, existing theories and proof scripts may require a few additional
   970 type constraints;
   971 
   972 * integer division and remainder can now be performed on constant
   973 arguments;
   974 
   975 * many properties of integer multiplication, division and remainder
   976 are now available;
   977 
   978 * An interface to the Stanford Validity Checker (SVC) is available through the
   979 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   980 are proved automatically.  SVC must be installed separately, and its results
   981 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   982 invocation of the underlying oracle).  For SVC see
   983   http://verify.stanford.edu/SVC
   984 
   985 * IsaMakefile: the HOL-Real target now builds an actual image;
   986 
   987 
   988 ** HOL misc **
   989 
   990 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   991 (in Isabelle/Isar) -- by Gertrud Bauer;
   992 
   993 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   994 analysis for assembly languages with subtypes;
   995 
   996 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   997 -- avoids syntactic ambiguities and treats state, transition, and
   998 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   999 changed syntax and (many) tactics;
  1000 
  1001 * HOL/inductive: Now also handles more general introduction rules such
  1002   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1003   theorems are now maintained within the theory (maintained via the
  1004   "mono" attribute);
  1005 
  1006 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1007   (using function types) such as
  1008 
  1009   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1010 
  1011 * HOL/record: record_simproc (part of the default simpset) takes care
  1012 of selectors applied to updated records; record_split_tac is no longer
  1013 part of the default claset; update_defs may now be removed from the
  1014 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1015 
  1016   claset_ref () := claset() addSWrapper record_split_wrapper;
  1017   Delsimprocs [record_simproc]
  1018 
  1019 * HOL/typedef: fixed type inference for representing set; type
  1020 arguments now have to occur explicitly on the rhs as type constraints;
  1021 
  1022 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1023 names rather than an ML expression;
  1024 
  1025 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1026 supplied later.  Program schemes can be defined, such as
  1027     "While B C s = (if B s then While B C (C s) else s)"
  1028 where the well-founded relation can be chosen after B and C have been given.
  1029 
  1030 * HOL/List: the constructors of type list are now Nil and Cons;
  1031 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1032 course, ML tools referring to List.list.op # etc. have to be adapted;
  1033 
  1034 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1035 disabled by default; run isabelle with option -m HOL to get back to
  1036 the original Gordon/HOL-style output;
  1037 
  1038 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1039 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1040 
  1041 * HOL basic syntax simplified (more orthogonal): all variants of
  1042 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1043 Eps operator is provided as well: "SOME x. P[x]";
  1044 
  1045 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1046 
  1047 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1048 thus available for user theories;
  1049 
  1050 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1051 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1052 time;
  1053 
  1054 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1055 several times and then mp;
  1056 
  1057 
  1058 *** LK ***
  1059 
  1060 * the notation <<...>> is now available as a notation for sequences of
  1061 formulas;
  1062 
  1063 * the simplifier is now installed
  1064 
  1065 * the axiom system has been generalized (thanks to Soren Heilmann)
  1066 
  1067 * the classical reasoner now has a default rule database
  1068 
  1069 
  1070 *** ZF ***
  1071 
  1072 * new primrec section allows primitive recursive functions to be given
  1073 directly (as in HOL) over datatypes and the natural numbers;
  1074 
  1075 * new tactics induct_tac and exhaust_tac for induction (or case
  1076 analysis) over datatypes and the natural numbers;
  1077 
  1078 * the datatype declaration of type T now defines the recursor T_rec;
  1079 
  1080 * simplification automatically does freeness reasoning for datatype
  1081 constructors;
  1082 
  1083 * automatic type-inference, with AddTCs command to insert new
  1084 type-checking rules;
  1085 
  1086 * datatype introduction rules are now added as Safe Introduction rules
  1087 to the claset;
  1088 
  1089 * the syntax "if P then x else y" is now available in addition to
  1090 if(P,x,y);
  1091 
  1092 
  1093 *** Internal programming interfaces ***
  1094 
  1095 * tuned simplifier trace output; new flag debug_simp;
  1096 
  1097 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1098 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1099 
  1100 * AxClass.axclass_tac lost the theory argument;
  1101 
  1102 * tuned current_goals_markers semantics: begin / end goal avoids
  1103 printing empty lines;
  1104 
  1105 * removed prs and prs_fn hook, which was broken because it did not
  1106 include \n in its semantics, forcing writeln to add one
  1107 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1108 string -> unit if you really want to output text without newline;
  1109 
  1110 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1111 plain output, interface builders may have to enable 'isabelle_font'
  1112 mode to get Isabelle font glyphs as before;
  1113 
  1114 * refined token_translation interface; INCOMPATIBILITY: output length
  1115 now of type real instead of int;
  1116 
  1117 * theory loader actions may be traced via new ThyInfo.add_hook
  1118 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1119 your own database of information attached to *whole* theories -- as
  1120 opposed to intra-theory data slots offered via TheoryDataFun;
  1121 
  1122 * proper handling of dangling sort hypotheses (at last!);
  1123 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1124 extra sort hypotheses that can be witnessed from the type signature;
  1125 the force_strip_shyps flag is gone, any remaining shyps are simply
  1126 left in the theorem (with a warning issued by strip_shyps_warning);
  1127 
  1128 
  1129 
  1130 New in Isabelle98-1 (October 1998)
  1131 ----------------------------------
  1132 
  1133 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1134 
  1135 * several changes of automated proof tools;
  1136 
  1137 * HOL: major changes to the inductive and datatype packages, including
  1138 some minor incompatibilities of theory syntax;
  1139 
  1140 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1141 called `inj_on';
  1142 
  1143 * HOL: removed duplicate thms in Arith:
  1144   less_imp_add_less  should be replaced by  trans_less_add1
  1145   le_imp_add_le      should be replaced by  trans_le_add1
  1146 
  1147 * HOL: unary minus is now overloaded (new type constraints may be
  1148 required);
  1149 
  1150 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1151 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1152 now taken as an integer constant.
  1153 
  1154 * Pure: ML function 'theory_of' renamed to 'theory';
  1155 
  1156 
  1157 *** Proof tools ***
  1158 
  1159 * Simplifier:
  1160   1. Asm_full_simp_tac is now more aggressive.
  1161      1. It will sometimes reorient premises if that increases their power to
  1162         simplify.
  1163      2. It does no longer proceed strictly from left to right but may also
  1164         rotate premises to achieve further simplification.
  1165      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1166      old Asm_full_simp_tac in that it does not rotate premises.
  1167   2. The simplifier now knows a little bit about nat-arithmetic.
  1168 
  1169 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1170 allows for selected deletion of wrappers, by introduction of names for
  1171 wrapper functionals.  This implies that addbefore, addSbefore,
  1172 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1173 and that adding two tactics with the same name overwrites the first
  1174 one (emitting a warning).
  1175   type wrapper = (int -> tactic) -> (int -> tactic)
  1176   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1177   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1178   delWrapper, delSWrapper: claset *  string            -> claset
  1179   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1180 
  1181 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1182 semantics; addbefore now affects only the unsafe part of step_tac
  1183 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1184 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1185 by Force_tac;
  1186 
  1187 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1188 compWrapper; added safe wrapper (and access functions for it);
  1189 
  1190 * HOL/split_all_tac is now much faster and fails if there is nothing
  1191 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1192 and the names of the automatically generated variables have changed.
  1193 split_all_tac has moved within claset() from unsafe wrappers to safe
  1194 wrappers, which means that !!-bound variables are split much more
  1195 aggressively, and safe_tac and clarify_tac now split such variables.
  1196 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1197 Note: the same holds for record_split_tac, which does the job of
  1198 split_all_tac for record fields.
  1199 
  1200 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1201 permanently to the default simpset using Addsplits just like
  1202 Addsimps. They can be removed via Delsplits just like
  1203 Delsimps. Lower-case versions are also available.
  1204 
  1205 * HOL/Simplifier: The rule split_if is now part of the default
  1206 simpset. This means that the simplifier will eliminate all occurrences
  1207 of if-then-else in the conclusion of a goal. To prevent this, you can
  1208 either remove split_if completely from the default simpset by
  1209 `Delsplits [split_if]' or remove it in a specific call of the
  1210 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1211 other case splitting rules to/from the default simpset: every datatype
  1212 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1213 t is the name of the datatype).
  1214 
  1215 * Classical reasoner / Simplifier combination: new force_tac (and
  1216 derivatives Force_tac, force) combines rewriting and classical
  1217 reasoning (and whatever other tools) similarly to auto_tac, but is
  1218 aimed to solve the given subgoal completely.
  1219 
  1220 
  1221 *** General ***
  1222 
  1223 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1224 and `goalw': the theory is no longer needed as an explicit argument -
  1225 the current theory context is used; assumptions are no longer returned
  1226 at the ML-level unless one of them starts with ==> or !!; it is
  1227 recommended to convert to these new commands using isatool fixgoal
  1228 (backup your sources first!);
  1229 
  1230 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1231 the current theory context, and 'theory' to lookup stored theories;
  1232 
  1233 * new theory section 'locale' for declaring constants, assumptions and
  1234 definitions that have local scope;
  1235 
  1236 * new theory section 'nonterminals' for purely syntactic types;
  1237 
  1238 * new theory section 'setup' for generic ML setup functions
  1239 (e.g. package initialization);
  1240 
  1241 * the distribution now includes Isabelle icons: see
  1242 lib/logo/isabelle-{small,tiny}.xpm;
  1243 
  1244 * isatool install - install binaries with absolute references to
  1245 ISABELLE_HOME/bin;
  1246 
  1247 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1248 
  1249 * print mode 'emacs' reserved for Isamode;
  1250 
  1251 * support multiple print (ast) translations per constant name;
  1252 
  1253 * theorems involving oracles are now printed with a suffixed [!];
  1254 
  1255 
  1256 *** HOL ***
  1257 
  1258 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1259 
  1260 * HOL/inductive package reorganized and improved: now supports mutual
  1261 definitions such as
  1262 
  1263   inductive EVEN ODD
  1264     intrs
  1265       null "0 : EVEN"
  1266       oddI "n : EVEN ==> Suc n : ODD"
  1267       evenI "n : ODD ==> Suc n : EVEN"
  1268 
  1269 new theorem list "elims" contains an elimination rule for each of the
  1270 recursive sets; inductive definitions now handle disjunctive premises
  1271 correctly (also ZF);
  1272 
  1273 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1274 "mutual_induct" no longer exists - the induction rule is always
  1275 contained in "induct";
  1276 
  1277 
  1278 * HOL/datatype package re-implemented and greatly improved: now
  1279 supports mutually recursive datatypes such as
  1280 
  1281   datatype
  1282     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1283             | SUM ('a aexp) ('a aexp)
  1284             | DIFF ('a aexp) ('a aexp)
  1285             | NUM 'a
  1286   and
  1287     'a bexp = LESS ('a aexp) ('a aexp)
  1288             | AND ('a bexp) ('a bexp)
  1289             | OR ('a bexp) ('a bexp)
  1290 
  1291 as well as indirectly recursive datatypes such as
  1292 
  1293   datatype
  1294     ('a, 'b) term = Var 'a
  1295                   | App 'b ((('a, 'b) term) list)
  1296 
  1297 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1298 induction on mutually / indirectly recursive datatypes.
  1299 
  1300 Primrec equations are now stored in theory and can be accessed via
  1301 <function_name>.simps.
  1302 
  1303 INCOMPATIBILITIES:
  1304 
  1305   - Theories using datatypes must now have theory Datatype as an
  1306     ancestor.
  1307   - The specific <typename>.induct_tac no longer exists - use the
  1308     generic induct_tac instead.
  1309   - natE has been renamed to nat.exhaust - use exhaust_tac
  1310     instead of res_inst_tac ... natE. Note that the variable
  1311     names in nat.exhaust differ from the names in natE, this
  1312     may cause some "fragile" proofs to fail.
  1313   - The theorems split_<typename>_case and split_<typename>_case_asm
  1314     have been renamed to <typename>.split and <typename>.split_asm.
  1315   - Since default sorts of type variables are now handled correctly,
  1316     some datatype definitions may have to be annotated with explicit
  1317     sort constraints.
  1318   - Primrec definitions no longer require function name and type
  1319     of recursive argument.
  1320 
  1321 Consider using isatool fixdatatype to adapt your theories and proof
  1322 scripts to the new package (backup your sources first!).
  1323 
  1324 
  1325 * HOL/record package: considerably improved implementation; now
  1326 includes concrete syntax for record types, terms, updates; theorems
  1327 for surjective pairing and splitting !!-bound record variables; proof
  1328 support is as follows:
  1329 
  1330   1) standard conversions (selectors or updates applied to record
  1331 constructor terms) are part of the standard simpset;
  1332 
  1333   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1334 made part of standard simpset and claset via addIffs;
  1335 
  1336   3) a tactic for record field splitting (record_split_tac) is part of
  1337 the standard claset (addSWrapper);
  1338 
  1339 To get a better idea about these rules you may retrieve them via
  1340 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1341 the name of your record type.
  1342 
  1343 The split tactic 3) conceptually simplifies by the following rule:
  1344 
  1345   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1346 
  1347 Thus any record variable that is bound by meta-all will automatically
  1348 blow up into some record constructor term, consequently the
  1349 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1350 solve record problems automatically.
  1351 
  1352 
  1353 * reorganized the main HOL image: HOL/Integ and String loaded by
  1354 default; theory Main includes everything;
  1355 
  1356 * automatic simplification of integer sums and comparisons, using cancellation;
  1357 
  1358 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1359 
  1360 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1361 
  1362 * many new identities for unions, intersections, set difference, etc.;
  1363 
  1364 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1365 called split_if, split_split, split_sum_case and split_nat_case (to go
  1366 with add/delsplits);
  1367 
  1368 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1369 (?x::unit) = (); this is made part of the default simpset, which COULD
  1370 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1371 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1372 unit_abs_eta_conv is added in order to counter the effect of
  1373 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1374 %u.f();
  1375 
  1376 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1377 makes more sense);
  1378 
  1379 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1380   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1381   disjointness reasoning but breaking a few old proofs.
  1382 
  1383 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1384 to 'converse' from 'inverse' (for compatibility with ZF and some
  1385 literature);
  1386 
  1387 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1388 the well-founded relation;
  1389 
  1390 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1391     Compl A.  The "Compl" syntax remains available as input syntax for this
  1392     release ONLY.
  1393 
  1394 * HOL/Update: new theory of function updates:
  1395     f(a:=b) == %x. if x=a then b else f x
  1396 may also be iterated as in f(a:=b,c:=d,...);
  1397 
  1398 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1399 
  1400 * HOL/List:
  1401   - new function list_update written xs[i:=v] that updates the i-th
  1402     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1403   - new function `upt' written [i..j(] which generates the list
  1404     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1405     bound write [i..j], which is a shorthand for [i..j+1(].
  1406   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1407 
  1408 * HOL/Arith:
  1409   - removed 'pred' (predecessor) function;
  1410   - generalized some theorems about n-1;
  1411   - many new laws about "div" and "mod";
  1412   - new laws about greatest common divisors (see theory ex/Primes);
  1413 
  1414 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1415 instead of "inverse";
  1416 
  1417 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1418   of the multiset ordering;
  1419 
  1420 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1421   (not included by default);
  1422 
  1423 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1424 
  1425 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1426   programs, i.e. different program variables may have different types.
  1427 
  1428 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1429   [previously, this check worked only if the rewrite rule was unconditional]
  1430   Now rew can involve either definitions or equalities (either == or =).
  1431 
  1432 
  1433 *** ZF ***
  1434 
  1435 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1436   only the theorems proved on ZF.ML;
  1437 
  1438 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1439   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1440   disjointness reasoning but breaking a few old proofs.
  1441 
  1442 * ZF/Update: new theory of function updates
  1443     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1444   may also be iterated as in f(a:=b,c:=d,...);
  1445 
  1446 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1447 
  1448 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1449   [previously, this check worked only if the rewrite rule was unconditional]
  1450   Now rew can involve either definitions or equalities (either == or =).
  1451 
  1452 * case_tac provided for compatibility with HOL
  1453     (like the old excluded_middle_tac, but with subgoals swapped)
  1454 
  1455 
  1456 *** Internal programming interfaces ***
  1457 
  1458 * Pure: several new basic modules made available for general use, see
  1459 also src/Pure/README;
  1460 
  1461 * improved the theory data mechanism to support encapsulation (data
  1462 kind name replaced by private Object.kind, acting as authorization
  1463 key); new type-safe user interface via functor TheoryDataFun; generic
  1464 print_data function becomes basically useless;
  1465 
  1466 * removed global_names compatibility flag -- all theory declarations
  1467 are qualified by default;
  1468 
  1469 * module Pure/Syntax now offers quote / antiquote translation
  1470 functions (useful for Hoare logic etc. with implicit dependencies);
  1471 see HOL/ex/Antiquote for an example use;
  1472 
  1473 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1474 cterm -> thm;
  1475 
  1476 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1477 subgoal;
  1478 
  1479 * Display.print_goals function moved to Locale.print_goals;
  1480 
  1481 * standard print function for goals supports current_goals_markers
  1482 variable for marking begin of proof, end of proof, start of goal; the
  1483 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1484 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1485 for example;
  1486 
  1487 
  1488 
  1489 New in Isabelle98 (January 1998)
  1490 --------------------------------
  1491 
  1492 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1493 
  1494 * changed lexical syntax of terms / types: dots made part of long
  1495 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1496 
  1497 * simpset (and claset) reference variable replaced by functions
  1498 simpset / simpset_ref;
  1499 
  1500 * no longer supports theory aliases (via merge) and non-trivial
  1501 implicit merge of thms' signatures;
  1502 
  1503 * most internal names of constants changed due to qualified names;
  1504 
  1505 * changed Pure/Sequence interface (see Pure/seq.ML);
  1506 
  1507 
  1508 *** General Changes ***
  1509 
  1510 * hierachically structured name spaces (for consts, types, axms, thms
  1511 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1512 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1513 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1514 long_names for fully qualified output names; NOTE: ML programs
  1515 (special tactics, packages etc.) referring to internal names may have
  1516 to be adapted to cope with fully qualified names; in case of severe
  1517 backward campatibility problems try setting 'global_names' at compile
  1518 time to have enrything declared within a flat name space; one may also
  1519 fine tune name declarations in theories via the 'global' and 'local'
  1520 section;
  1521 
  1522 * reimplemented the implicit simpset and claset using the new anytype
  1523 data filed in signatures; references simpset:simpset ref etc. are
  1524 replaced by functions simpset:unit->simpset and
  1525 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1526 to patch your ML files accordingly;
  1527 
  1528 * HTML output now includes theory graph data for display with Java
  1529 applet or isatool browser; data generated automatically via isatool
  1530 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1531 
  1532 * defs may now be conditional; improved rewrite_goals_tac to handle
  1533 conditional equations;
  1534 
  1535 * defs now admits additional type arguments, using TYPE('a) syntax;
  1536 
  1537 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1538 creates a new theory node; implicit merge of thms' signatures is
  1539 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1540 transfer:theory->thm->thm in (rare) cases;
  1541 
  1542 * improved handling of draft signatures / theories; draft thms (and
  1543 ctyps, cterms) are automatically promoted to real ones;
  1544 
  1545 * slightly changed interfaces for oracles: admit many per theory, named
  1546 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1547 
  1548 * print_goals: optional output of const types (set show_consts and
  1549 show_types);
  1550 
  1551 * improved output of warnings (###) and errors (***);
  1552 
  1553 * subgoal_tac displays a warning if the new subgoal has type variables;
  1554 
  1555 * removed old README and Makefiles;
  1556 
  1557 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1558 
  1559 * removed obsolete init_pps and init_database;
  1560 
  1561 * deleted the obsolete tactical STATE, which was declared by
  1562     fun STATE tacfun st = tacfun st st;
  1563 
  1564 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1565 (which abbreviates $HOME);
  1566 
  1567 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1568 use isatool fixseq to adapt your ML programs (this works for fully
  1569 qualified references to the Sequence structure only!);
  1570 
  1571 * use_thy no longer requires writable current directory; it always
  1572 reloads .ML *and* .thy file, if either one is out of date;
  1573 
  1574 
  1575 *** Classical Reasoner ***
  1576 
  1577 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1578 tactics that use classical reasoning to simplify a subgoal without
  1579 splitting it into several subgoals;
  1580 
  1581 * Safe_tac: like safe_tac but uses the default claset;
  1582 
  1583 
  1584 *** Simplifier ***
  1585 
  1586 * added simplification meta rules:
  1587     (asm_)(full_)simplify: simpset -> thm -> thm;
  1588 
  1589 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1590 logics (again);
  1591 
  1592 * added prems argument to simplification procedures;
  1593 
  1594 * HOL, FOL, ZF: added infix function `addsplits':
  1595   instead of `<simpset> setloop (split_tac <thms>)'
  1596   you can simply write `<simpset> addsplits <thms>'
  1597 
  1598 
  1599 *** Syntax ***
  1600 
  1601 * TYPE('a) syntax for type reflection terms;
  1602 
  1603 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1604 
  1605 * pretty printer: changed order of mixfix annotation preference (again!);
  1606 
  1607 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1608 
  1609 
  1610 *** HOL ***
  1611 
  1612 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1613   with `addloop' of the simplifier to faciliate case splitting in premises.
  1614 
  1615 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1616 
  1617 * HOL/Auth: new protocol proofs including some for the Internet
  1618   protocol TLS;
  1619 
  1620 * HOL/Map: new theory of `maps' a la VDM;
  1621 
  1622 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1623 cancelling out common nat summands from =, <, <= (in)equalities, or
  1624 differences; simplification procedures nat_cancel_factor for
  1625 cancelling common factor from =, <, <= (in)equalities over natural
  1626 sums; nat_cancel contains both kinds of procedures, it is installed by
  1627 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1628 
  1629 * HOL/simplifier: terms of the form
  1630   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1631   are rewritten to
  1632   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1633   and those of the form
  1634   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1635   are rewritten to
  1636   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1637 
  1638 * HOL/datatype
  1639   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1640 
  1641   P(t_case f1 ... fn x) =
  1642      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1643         ...
  1644        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1645      )
  1646 
  1647   and a theorem `split_t_case_asm' of the form
  1648 
  1649   P(t_case f1 ... fn x) =
  1650     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1651         ...
  1652        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1653      )
  1654   which can be added to a simpset via `addsplits'. The existing theorems
  1655   expand_list_case and expand_option_case have been renamed to
  1656   split_list_case and split_option_case.
  1657 
  1658 * HOL/Arithmetic:
  1659   - `pred n' is automatically converted to `n-1'.
  1660     Users are strongly encouraged not to use `pred' any longer,
  1661     because it will disappear altogether at some point.
  1662   - Users are strongly encouraged to write "0 < n" rather than
  1663     "n ~= 0". Theorems and proof tools have been modified towards this
  1664     `standard'.
  1665 
  1666 * HOL/Lists:
  1667   the function "set_of_list" has been renamed "set" (and its theorems too);
  1668   the function "nth" now takes its arguments in the reverse order and
  1669   has acquired the infix notation "!" as in "xs!n".
  1670 
  1671 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1672 
  1673 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1674   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1675 
  1676 * HOL/record: extensible records with schematic structural subtyping
  1677 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1678 still lacks various theorems and concrete record syntax;
  1679 
  1680 
  1681 *** HOLCF ***
  1682 
  1683 * removed "axioms" and "generated by" sections;
  1684 
  1685 * replaced "ops" section by extended "consts" section, which is capable of
  1686   handling the continuous function space "->" directly;
  1687 
  1688 * domain package:
  1689   . proves theorems immediately and stores them in the theory,
  1690   . creates hierachical name space,
  1691   . now uses normal mixfix annotations (instead of cinfix...),
  1692   . minor changes to some names and values (for consistency),
  1693   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1694   . separator between mutual domain defs: changed "," to "and",
  1695   . improved handling of sort constraints;  now they have to
  1696     appear on the left-hand side of the equations only;
  1697 
  1698 * fixed LAM <x,y,zs>.b syntax;
  1699 
  1700 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1701 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1702 
  1703 
  1704 *** FOL and ZF ***
  1705 
  1706 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1707   with `addloop' of the simplifier to faciliate case splitting in premises.
  1708 
  1709 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1710 in HOL, they strip ALL and --> from proved theorems;
  1711 
  1712 
  1713 
  1714 New in Isabelle94-8 (May 1997)
  1715 ------------------------------
  1716 
  1717 *** General Changes ***
  1718 
  1719 * new utilities to build / run / maintain Isabelle etc. (in parts
  1720 still somewhat experimental); old Makefiles etc. still functional;
  1721 
  1722 * new 'Isabelle System Manual';
  1723 
  1724 * INSTALL text, together with ./configure and ./build scripts;
  1725 
  1726 * reimplemented type inference for greater efficiency, better error
  1727 messages and clean internal interface;
  1728 
  1729 * prlim command for dealing with lots of subgoals (an easier way of
  1730 setting goals_limit);
  1731 
  1732 
  1733 *** Syntax ***
  1734 
  1735 * supports alternative (named) syntax tables (parser and pretty
  1736 printer); internal interface is provided by add_modesyntax(_i);
  1737 
  1738 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1739 be used in conjunction with the Isabelle symbol font; uses the
  1740 "symbols" syntax table;
  1741 
  1742 * added token_translation interface (may translate name tokens in
  1743 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1744 the current print_mode); IMPORTANT: user print translation functions
  1745 are responsible for marking newly introduced bounds
  1746 (Syntax.mark_boundT);
  1747 
  1748 * token translations for modes "xterm" and "xterm_color" that display
  1749 names in bold, underline etc. or colors (which requires a color
  1750 version of xterm);
  1751 
  1752 * infixes may now be declared with names independent of their syntax;
  1753 
  1754 * added typed_print_translation (like print_translation, but may
  1755 access type of constant);
  1756 
  1757 
  1758 *** Classical Reasoner ***
  1759 
  1760 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  1761 some limitations.  Blast_tac...
  1762   + ignores addss, addbefore, addafter; this restriction is intrinsic
  1763   + ignores elimination rules that don't have the correct format
  1764         (the conclusion MUST be a formula variable)
  1765   + ignores types, which can make HOL proofs fail
  1766   + rules must not require higher-order unification, e.g. apply_type in ZF
  1767     [message "Function Var's argument not a bound variable" relates to this]
  1768   + its proof strategy is more general but can actually be slower
  1769 
  1770 * substitution with equality assumptions no longer permutes other
  1771 assumptions;
  1772 
  1773 * minor changes in semantics of addafter (now called addaltern); renamed
  1774 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  1775 (and access functions for it);
  1776 
  1777 * improved combination of classical reasoner and simplifier:
  1778   + functions for handling clasimpsets
  1779   + improvement of addss: now the simplifier is called _after_ the
  1780     safe steps.
  1781   + safe variant of addss called addSss: uses safe simplifications
  1782     _during_ the safe steps. It is more complete as it allows multiple
  1783     instantiations of unknowns (e.g. with slow_tac).
  1784 
  1785 *** Simplifier ***
  1786 
  1787 * added interface for simplification procedures (functions that
  1788 produce *proven* rewrite rules on the fly, depending on current
  1789 redex);
  1790 
  1791 * ordering on terms as parameter (used for ordered rewriting);
  1792 
  1793 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  1794 
  1795 * the solver is now split into a safe and an unsafe part.
  1796 This should be invisible for the normal user, except that the
  1797 functions setsolver and addsolver have been renamed to setSolver and
  1798 addSolver; added safe_asm_full_simp_tac;
  1799 
  1800 
  1801 *** HOL ***
  1802 
  1803 * a generic induction tactic `induct_tac' which works for all datatypes and
  1804 also for type `nat';
  1805 
  1806 * a generic case distinction tactic `exhaust_tac' which works for all
  1807 datatypes and also for type `nat';
  1808 
  1809 * each datatype comes with a function `size';
  1810 
  1811 * patterns in case expressions allow tuple patterns as arguments to
  1812 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1813 
  1814 * primrec now also works with type nat;
  1815 
  1816 * recdef: a new declaration form, allows general recursive functions to be
  1817 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1818 
  1819 * the constant for negation has been renamed from "not" to "Not" to
  1820 harmonize with FOL, ZF, LK, etc.;
  1821 
  1822 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1823 infinite lists;
  1824 
  1825 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1826 
  1827 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1828 problems in commutative rings, using axiomatic type classes for + and *;
  1829 
  1830 * more examples in HOL/MiniML and HOL/Auth;
  1831 
  1832 * more default rewrite rules for quantifiers, union/intersection;
  1833 
  1834 * a new constant `arbitrary == @x.False';
  1835 
  1836 * HOLCF/IOA replaces old HOL/IOA;
  1837 
  1838 * HOLCF changes: derived all rules and arities
  1839   + axiomatic type classes instead of classes
  1840   + typedef instead of faking type definitions
  1841   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1842   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1843   + eliminated the types void, one, tr
  1844   + use unit lift and bool lift (with translations) instead of one and tr
  1845   + eliminated blift from Lift3.thy (use Def instead of blift)
  1846   all eliminated rules are derived as theorems --> no visible changes ;
  1847 
  1848 
  1849 *** ZF ***
  1850 
  1851 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1852 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1853 as ZF_cs addSIs [equalityI];
  1854 
  1855 
  1856 
  1857 New in Isabelle94-7 (November 96)
  1858 ---------------------------------
  1859 
  1860 * allowing negative levels (as offsets) in prlev and choplev;
  1861 
  1862 * super-linear speedup for large simplifications;
  1863 
  1864 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1865 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1866 FAIL); can suppress it using the command Delsimps (ex_simps @
  1867 all_simps); De Morgan laws are also now included, by default;
  1868 
  1869 * improved printing of ==>  :  ~:
  1870 
  1871 * new object-logic "Sequents" adds linear logic, while replacing LK
  1872 and Modal (thanks to Sara Kalvala);
  1873 
  1874 * HOL/Auth: correctness proofs for authentication protocols;
  1875 
  1876 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1877 examples on HOL/Auth);
  1878 
  1879 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1880 the rewriter and classical reasoner simultaneously;
  1881 
  1882 * function uresult no longer returns theorems in "standard" format;
  1883 regain previous version by: val uresult = standard o uresult;
  1884 
  1885 
  1886 
  1887 New in Isabelle94-6
  1888 -------------------
  1889 
  1890 * oracles -- these establish an interface between Isabelle and trusted
  1891 external reasoners, which may deliver results as theorems;
  1892 
  1893 * proof objects (in particular record all uses of oracles);
  1894 
  1895 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1896 
  1897 * "constdefs" section in theory files;
  1898 
  1899 * "primrec" section (HOL) no longer requires names;
  1900 
  1901 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1902 
  1903 
  1904 
  1905 New in Isabelle94-5
  1906 -------------------
  1907 
  1908 * reduced space requirements;
  1909 
  1910 * automatic HTML generation from theories;
  1911 
  1912 * theory files no longer require "..." (quotes) around most types;
  1913 
  1914 * new examples, including two proofs of the Church-Rosser theorem;
  1915 
  1916 * non-curried (1994) version of HOL is no longer distributed;
  1917 
  1918 
  1919 
  1920 New in Isabelle94-4
  1921 -------------------
  1922 
  1923 * greatly reduced space requirements;
  1924 
  1925 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1926 
  1927 * searchable theorem database (see the section "Retrieving theorems" on
  1928 page 8 of the Reference Manual);
  1929 
  1930 * new examples, including Grabczewski's monumental case study of the
  1931 Axiom of Choice;
  1932 
  1933 * The previous version of HOL renamed to Old_HOL;
  1934 
  1935 * The new version of HOL (previously called CHOL) uses a curried syntax
  1936 for functions.  Application looks like f a b instead of f(a,b);
  1937 
  1938 * Mutually recursive inductive definitions finally work in HOL;
  1939 
  1940 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1941 translates to the operator "split";
  1942 
  1943 
  1944 
  1945 New in Isabelle94-3
  1946 -------------------
  1947 
  1948 * new infix operator, addss, allowing the classical reasoner to
  1949 perform simplification at each step of its search.  Example:
  1950         fast_tac (cs addss ss)
  1951 
  1952 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1953 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1954 look like (a,b) instead of <a,b>;
  1955 
  1956 * PLEASE NOTE: CHOL will eventually replace HOL!
  1957 
  1958 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1959 It translates to the operator "split".  A new theory of integers is available;
  1960 
  1961 * In ZF, integer numerals now denote two's-complement binary integers.
  1962 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1963 
  1964 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1965 of the Axiom of Choice;
  1966 
  1967 
  1968 
  1969 New in Isabelle94-2
  1970 -------------------
  1971 
  1972 * Significantly faster resolution;
  1973 
  1974 * the different sections in a .thy file can now be mixed and repeated
  1975 freely;
  1976 
  1977 * Database of theorems for FOL, HOL and ZF.  New
  1978 commands including qed, qed_goal and bind_thm store theorems in the database.
  1979 
  1980 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1981 a given theory (thms_of), or find out what theory a theorem was proved in
  1982 (theory_of_thm);
  1983 
  1984 * Bugs fixed in the inductive definition and datatype packages;
  1985 
  1986 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1987 and HOL_dup_cs obsolete;
  1988 
  1989 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1990 have been removed;
  1991 
  1992 * Simpler definition of function space in ZF;
  1993 
  1994 * new results about cardinal and ordinal arithmetic in ZF;
  1995 
  1996 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1997 types;
  1998 
  1999 
  2000 $Id$