NEWS
author wenzelm
Tue Oct 30 17:33:56 2001 +0100 (2001-10-30)
changeset 11986 26b95a6f3f79
parent 11965 c84eb86d9a5f
child 11995 4a622f5fb164
permissions -rw-r--r--
- 'induct' method now derives symbolic cases from the *rulified* rule
(before it used to rulify cases stemming from the internal atomized
version); this means that the context of a non-atomic statement
becomes is included in the hypothesis, avoiding the slightly
cumbersome show "PROP ?case" form;
     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 
    37   - 'case' command admits impromptu naming of parameters (such as
    38 "case (Suc n)");
    39 
    40   - 'induct' method divinates rule instantiation from the inductive
    41 claim; no longer requires excessive ?P bindings for proper
    42 instantiation of cases;
    43 
    44   - 'induct' method properly enumerates all possibilities of set/type
    45 rules; as a consequence facts may be also passed through *type* rules
    46 without further ado;
    47 
    48   - 'induct' method now derives symbolic cases from the *rulified*
    49 rule (before it used to rulify cases stemming from the internal
    50 atomized version); this means that the context of a non-atomic
    51 statement becomes is included in the hypothesis, avoiding the slightly
    52 cumbersome show "PROP ?case" form;
    53 
    54   - removed obsolete "(simplified)" and "(stripped)" options of methods;
    55   - added 'print_induct_rules' (covered by help item in Proof General > 3.3);
    56   - moved induct/cases attributes to Pure, methods to Provers;
    57   - generic method setup instantiated for FOL and HOL;
    58 
    59 * Pure: renamed "antecedent" case to "rule_context";
    60 
    61 * Pure: added 'corollary' command;
    62 
    63 * Pure: fixed 'token_translation' command;
    64 
    65 * Pure: removed obsolete 'exported' attribute;
    66 
    67 * Pure: dummy pattern "_" in is/let is now automatically lifted over
    68 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
    69 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
    70 
    71 * Pure: method 'atomize' presents local goal premises as object-level
    72 statements (atomic meta-level propositions); setup controlled via
    73 rewrite rules declarations of 'atomize' attribute; example
    74 application: 'induct' method with proper rule statements in improper
    75 proof *scripts*;
    76 
    77 * Provers: 'simplified' attribute may refer to explicit rules instead
    78 of full simplifier context; 'iff' attribute handles conditional rules;
    79 
    80 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
    81 
    82 * HOL: 'recdef' now fails on unfinished automated proofs, use
    83 "(permissive)" option to recover old behavior;
    84 
    85 * HOL: 'inductive' no longer features separate (collective) attributes
    86 for 'intros' (was found too confusing);
    87 
    88 
    89 
    90 *** HOL ***
    91 
    92 * HOL: moved over to sane numeral syntax; the new policy is as
    93 follows:
    94 
    95   - 0 and 1 are polymorphic constants, which are defined on any
    96   numeric type (nat, int, real etc.);
    97 
    98   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
    99   binary representation internally;
   100 
   101   - type nat has special constructor Suc, and generally prefers Suc 0
   102   over 1::nat and Suc (Suc 0) over 2::nat;
   103 
   104 This change may cause significant INCOMPATIBILITIES; here are some
   105 hints on converting existing sources:
   106 
   107   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   108   entities, so expressions involving "-" (unary or binary minus) need
   109   to be spaced properly;
   110 
   111   - existing occurrences of "1" may need to be constraint "1::nat" or
   112   even replaced by Suc 0; similar for old "2";
   113 
   114   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   115 
   116   - remove all special provisions on numerals in proofs;
   117 
   118 * HOL/record:
   119   - removed old "make" and "make_scheme" operations -- INCOMPATIBILITY;
   120   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   121   - provides cases/induct rules for use with corresponding Isar methods;
   122   - new derived operations "make" (for adding fields of current
   123     record), "extend" to promote fixed record to record scheme, and
   124     "truncate" for the reverse; cf. theorems "derived_defs", which are
   125     *not* declared as simp by default;
   126   - internal definitions directly based on a light-weight abstract
   127     theory of product types over typedef rather than datatype;
   128 
   129 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   130 
   131 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   132 (beware of argument permutation!);
   133 
   134 * HOL: linorder_less_split superseded by linorder_cases;
   135 
   136 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   137 to peripheral theory "Hilbert_Choice";
   138 
   139 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   140 in this (rare) case use:
   141 
   142   delSWrapper "split_all_tac"
   143   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   144 
   145 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   146 MAY FAIL;
   147 
   148 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   149 Isabelle's type classes, ^ on functions and relations has too general
   150 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   151 necessary to attach explicit type constraints;
   152 
   153 * HOL: syntax translations now work properly with numerals and records
   154 expressions;
   155 
   156 * HOL/GroupTheory: group theory examples including Sylow's theorem, by
   157 Florian Kammüller;
   158 
   159 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   160 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   161 renamed "Product_Type.unit";
   162 
   163 
   164 *** ZF ***
   165 
   166 * ZF: the integer library now covers quotients and remainders, with
   167 many laws relating division to addition, multiplication, etc.;
   168 
   169 
   170 *** General ***
   171 
   172 * kernel: meta-level proof terms (by Stefan Berghofer), see also ref
   173 manual;
   174 
   175 * Pure/axclass: removed obsolete ML interface goal_subclass/goal_arity;
   176 
   177 * classical: renamed addaltern to addafter, addSaltern to addSafter;
   178 
   179 * clasimp: ``iff'' declarations now handle conditional rules as well;
   180 
   181 * syntax: new token syntax "num" for plain numerals (without "#" of
   182 "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now separate
   183 tokens, so expressions involving minus need to be spaced properly;
   184 
   185 * syntax: support non-oriented infixes;
   186 
   187 * syntax: print modes "type_brackets" and "no_type_brackets" control
   188 output of nested => (types); the default behavior is "type_brackets";
   189 
   190 * syntax: builtin parse translation for "_constify" turns valued
   191 tokens into AST constants;
   192 
   193 * system: support Poly/ML 4.1.1 (now able to manage large heaps);
   194 
   195 * system: Proof General keywords specification is now part of the
   196 Isabelle distribution (see etc/isar-keywords.el);
   197 
   198 * system: smart selection of Isabelle process versus Isabelle
   199 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   200 run both "isabelle" and "Isabelle" even if file names are badly
   201 damaged (executable inspects the case of the first letter of its own
   202 name); added separate "isabelle-process" and "isabelle-interface";
   203 
   204 
   205 
   206 New in Isabelle99-2 (February 2001)
   207 -----------------------------------
   208 
   209 *** Overview of INCOMPATIBILITIES ***
   210 
   211 * HOL: please note that theories in the Library and elsewhere often use the
   212 new-style (Isar) format; to refer to their theorems in an ML script you must
   213 bind them to ML identifers by e.g.	val thm_name = thm "thm_name";
   214 
   215 * HOL: inductive package no longer splits induction rule aggressively,
   216 but only as far as specified by the introductions given; the old
   217 format may be recovered via ML function complete_split_rule or attribute
   218 'split_rule (complete)';
   219 
   220 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   221 gfp_Tarski to gfp_unfold;
   222 
   223 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   224 
   225 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   226 relation); infix "^^" has been renamed "``"; infix "``" has been
   227 renamed "`"; "univalent" has been renamed "single_valued";
   228 
   229 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   230 operation;
   231 
   232 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   233 
   234 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   235 
   236 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   237 consequence, it is no longer monotonic wrt. the local goal context
   238 (which is now passed through the inductive cases);
   239 
   240 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   241 \<gg> to \<ggreater>;
   242 
   243 
   244 *** Document preparation ***
   245 
   246 * \isabellestyle{NAME} selects version of Isabelle output (currently
   247 available: are "it" for near math-mode best-style output, "sl" for
   248 slanted text style, and "tt" for plain type-writer; if no
   249 \isabellestyle command is given, output is according to slanted
   250 type-writer);
   251 
   252 * support sub/super scripts (for single symbols only), input syntax is
   253 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   254 
   255 * some more standard symbols; see Appendix A of the system manual for
   256 the complete list of symbols defined in isabellesym.sty;
   257 
   258 * improved isabelle style files; more abstract symbol implementation
   259 (should now use \isamath{...} and \isatext{...} in custom symbol
   260 definitions);
   261 
   262 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   263 state; Note that presentation of goal states does not conform to
   264 actual human-readable proof documents.  Please do not include goal
   265 states into document output unless you really know what you are doing!
   266 
   267 * proper indentation of antiquoted output with proportional LaTeX
   268 fonts;
   269 
   270 * no_document ML operator temporarily disables LaTeX document
   271 generation;
   272 
   273 * isatool unsymbolize tunes sources for plain ASCII communication;
   274 
   275 
   276 *** Isar ***
   277 
   278 * Pure: Isar now suffers initial goal statements to contain unbound
   279 schematic variables (this does not conform to actual readable proof
   280 documents, due to unpredictable outcome and non-compositional proof
   281 checking); users who know what they are doing may use schematic goals
   282 for Prolog-style synthesis of proven results;
   283 
   284 * Pure: assumption method (an implicit finishing) now handles actual
   285 rules as well;
   286 
   287 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   288 initial goal, declare "that" only as Pure intro (only for single
   289 steps); the "that" rule assumption may now be involved in implicit
   290 finishing, thus ".." becomes a feasible for trivial obtains;
   291 
   292 * Pure: default proof step now includes 'intro_classes'; thus trivial
   293 instance proofs may be performed by "..";
   294 
   295 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   296 statements as well;
   297 
   298 * Pure: more robust selection of calculational rules;
   299 
   300 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   301 rule (as well as the assumption rule);
   302 
   303 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   304 lemmas, using the graph browser tool;
   305 
   306 * Pure: predict failure of "show" in interactive mode;
   307 
   308 * Pure: 'thms_containing' now takes actual terms as arguments;
   309 
   310 * HOL: improved method 'induct' --- now handles non-atomic goals
   311 (potential INCOMPATIBILITY); tuned error handling;
   312 
   313 * HOL: cases and induct rules now provide explicit hints about the
   314 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   315 any remaining facts are inserted into the goal verbatim;
   316 
   317 * HOL: local contexts (aka cases) may now contain term bindings as
   318 well; the 'cases' and 'induct' methods new provide a ?case binding for
   319 the result to be shown in each case;
   320 
   321 * HOL: added 'recdef_tc' command;
   322 
   323 * isatool convert assists in eliminating legacy ML scripts;
   324 
   325 
   326 *** HOL ***
   327 
   328 * HOL/Library: a collection of generic theories to be used together
   329 with main HOL; the theory loader path already includes this directory
   330 by default; the following existing theories have been moved here:
   331 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   332 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   333 
   334 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   335 modelling and verification task performed in Isabelle/HOL +
   336 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   337 
   338 * HOL/Algebra: special summation operator SUM no longer exists, it has
   339 been replaced by setsum; infix 'assoc' now has priority 50 (like
   340 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   341 'domain', this makes the theory consistent with mathematical
   342 literature;
   343 
   344 * HOL basics: added overloaded operations "inverse" and "divide"
   345 (infix "/"), syntax for generic "abs" operation, generic summation
   346 operator \<Sum>;
   347 
   348 * HOL/typedef: simplified package, provide more useful rules (see also
   349 HOL/subset.thy);
   350 
   351 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   352 now expressed as a proper nested rule (old-style tactic scripts may
   353 require atomize_strip_tac to cope with non-atomic premises);
   354 
   355 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   356 to "split_conv" (old name still available for compatibility);
   357 
   358 * HOL: improved concrete syntax for strings (e.g. allows translation
   359 rules with string literals);
   360 
   361 * HOL-Hyperreal: a new target, extending HOL-Real with the hyperreals
   362 and Fleuriot's mechanization of analysis;
   363 
   364 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   365 
   366 
   367 *** CTT ***
   368 
   369 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   370 "lam" is displayed as TWO lambda-symbols
   371 
   372 * CTT: theory Main now available, containing everything (that is, Bool
   373 and Arith);
   374 
   375 
   376 *** General ***
   377 
   378 * Pure: the Simplifier has been implemented properly as a derived rule
   379 outside of the actual kernel (at last!); the overall performance
   380 penalty in practical applications is about 50%, while reliability of
   381 the Isabelle inference kernel has been greatly improved;
   382 
   383 * print modes "brackets" and "no_brackets" control output of nested =>
   384 (types) and ==> (props); the default behaviour is "brackets";
   385 
   386 * Provers: fast_tac (and friends) now handle actual object-logic rules
   387 as assumptions as well;
   388 
   389 * system: support Poly/ML 4.0;
   390 
   391 * system: isatool install handles KDE version 1 or 2;
   392 
   393 
   394 
   395 New in Isabelle99-1 (October 2000)
   396 ----------------------------------
   397 
   398 *** Overview of INCOMPATIBILITIES ***
   399 
   400 * HOL: simplification of natural numbers is much changed; to partly
   401 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   402 issue the following ML commands:
   403 
   404   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   405   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   406 
   407 * HOL: simplification no longer dives into case-expressions; this is
   408 controlled by "t.weak_case_cong" for each datatype t;
   409 
   410 * HOL: nat_less_induct renamed to less_induct;
   411 
   412 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   413 fixsome to patch .thy and .ML sources automatically;
   414 
   415   select_equality  -> some_equality
   416   select_eq_Ex     -> some_eq_ex
   417   selectI2EX       -> someI2_ex
   418   selectI2         -> someI2
   419   selectI          -> someI
   420   select1_equality -> some1_equality
   421   Eps_sym_eq       -> some_sym_eq_trivial
   422   Eps_eq           -> some_eq_trivial
   423 
   424 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   425 
   426 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   427 instead);
   428 
   429 * HOL: the recursion equations generated by 'recdef' are now called
   430 f.simps instead of f.rules;
   431 
   432 * HOL: qed_spec_mp now also handles bounded ALL as well;
   433 
   434 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
   435 sometimes be needed;
   436 
   437 * HOL: the constant for "f``x" is now "image" rather than "op ``";
   438 
   439 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
   440 
   441 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
   442 product is now "<*>" instead of "Times"; the lexicographic product is
   443 now "<*lex*>" instead of "**";
   444 
   445 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
   446 of main HOL, but was unused); better use HOL's datatype package;
   447 
   448 * HOL: removed "symbols" syntax for constant "override" of theory Map;
   449 the old syntax may be recovered as follows:
   450 
   451   syntax (symbols)
   452     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
   453       (infixl "\\<oplus>" 100)
   454 
   455 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   456 
   457 * HOL/ML: even fewer consts are declared as global (see theories Ord,
   458 Lfp, Gfp, WF); this only affects ML packages that refer to const names
   459 internally;
   460 
   461 * HOL and ZF: syntax for quotienting wrt an equivalence relation
   462 changed from A/r to A//r;
   463 
   464 * ZF: new treatment of arithmetic (nat & int) may break some old
   465 proofs;
   466 
   467 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
   468 rulify -> rule_format, elimify -> elim_format, ...);
   469 
   470 * Isar/Provers: intro/elim/dest attributes changed; renamed
   471 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
   472 should have to change intro!! to intro? only); replaced "delrule" by
   473 "rule del";
   474 
   475 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
   476 
   477 * Provers: strengthened force_tac by using new first_best_tac;
   478 
   479 * LaTeX document preparation: several changes of isabelle.sty (see
   480 lib/texinputs);
   481 
   482 
   483 *** Document preparation ***
   484 
   485 * formal comments (text blocks etc.) in new-style theories may now
   486 contain antiquotations of thm/prop/term/typ/text to be presented
   487 according to latex print mode; concrete syntax is like this:
   488 @{term[show_types] "f(x) = a + x"};
   489 
   490 * isatool mkdir provides easy setup of Isabelle session directories,
   491 including proper document sources;
   492 
   493 * generated LaTeX sources are now deleted after successful run
   494 (isatool document -c); may retain a copy somewhere else via -D option
   495 of isatool usedir;
   496 
   497 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   498 style files, achieving self-contained LaTeX sources and simplifying
   499 LaTeX debugging;
   500 
   501 * old-style theories now produce (crude) LaTeX output as well;
   502 
   503 * browser info session directories are now self-contained (may be put
   504 on WWW server seperately); improved graphs of nested sessions; removed
   505 graph for 'all sessions';
   506 
   507 * several improvements in isabelle style files; \isabellestyle{it}
   508 produces fake math mode output; \isamarkupheader is now \section by
   509 default; see lib/texinputs/isabelle.sty etc.;
   510 
   511 
   512 *** Isar ***
   513 
   514 * Isar/Pure: local results and corresponding term bindings are now
   515 subject to Hindley-Milner polymorphism (similar to ML); this
   516 accommodates incremental type-inference very nicely;
   517 
   518 * Isar/Pure: new derived language element 'obtain' supports
   519 generalized existence reasoning;
   520 
   521 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
   522 support accumulation of results, without applying any rules yet;
   523 useful to collect intermediate results without explicit name
   524 references, and for use with transitivity rules with more than 2
   525 premises;
   526 
   527 * Isar/Pure: scalable support for case-analysis type proofs: new
   528 'case' language element refers to local contexts symbolically, as
   529 produced by certain proof methods; internally, case names are attached
   530 to theorems as "tags";
   531 
   532 * Isar/Pure: theory command 'hide' removes declarations from
   533 class/type/const name spaces;
   534 
   535 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
   536 indicate potential overloading;
   537 
   538 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
   539 
   540 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
   541 "{a,b,c}" instead of {a,b,c};
   542 
   543 * Isar/Pure now provides its own version of intro/elim/dest
   544 attributes; useful for building new logics, but beware of confusion
   545 with the version in Provers/classical;
   546 
   547 * Isar/Pure: the local context of (non-atomic) goals is provided via
   548 case name 'antecedent';
   549 
   550 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
   551 to the current context is now done automatically);
   552 
   553 * Isar/Pure: theory command 'method_setup' provides a simple interface
   554 for definining proof methods in ML;
   555 
   556 * Isar/Provers: intro/elim/dest attributes changed; renamed
   557 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
   558 most cases, one should have to change intro!! to intro? only);
   559 replaced "delrule" by "rule del";
   560 
   561 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
   562 'symmetric' attribute (the latter supercedes [RS sym]);
   563 
   564 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
   565 method modifier); 'simp' method: 'only:' modifier removes loopers as
   566 well (including splits);
   567 
   568 * Isar/Provers: Simplifier and Classical methods now support all kind
   569 of modifiers used in the past, including 'cong', 'iff', etc.
   570 
   571 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
   572 of Simplifier and Classical reasoner);
   573 
   574 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
   575 now support named cases; major packages (inductive, datatype, primrec,
   576 recdef) support case names and properly name parameters;
   577 
   578 * Isar/HOL: new transitivity rules for substitution in inequalities --
   579 monotonicity conditions are extracted to be proven at end of
   580 calculations;
   581 
   582 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
   583 method anyway;
   584 
   585 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
   586 split_if split_if_asm; datatype package provides theorems foo.splits =
   587 foo.split foo.split_asm for each datatype;
   588 
   589 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
   590 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
   591 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
   592 use "(cases (simplified))" method in proper proof texts);
   593 
   594 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
   595 
   596 * Isar: names of theorems etc. may be natural numbers as well;
   597 
   598 * Isar: 'pr' command: optional arguments for goals_limit and
   599 ProofContext.prems_limit; no longer prints theory contexts, but only
   600 proof states;
   601 
   602 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   603 additional print modes to be specified; e.g. "pr(latex)" will print
   604 proof state according to the Isabelle LaTeX style;
   605 
   606 * Isar: improved support for emulating tactic scripts, including proof
   607 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   608 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   609 (for HOL datatypes);
   610 
   611 * Isar: simplified (more robust) goal selection of proof methods: 1st
   612 goal, all goals, or explicit goal specifier (tactic emulation); thus
   613 'proof method scripts' have to be in depth-first order;
   614 
   615 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
   616 
   617 * Isar: removed 'help' command, which hasn't been too helpful anyway;
   618 should instead use individual commands for printing items
   619 (print_commands, print_methods etc.);
   620 
   621 * Isar: added 'nothing' --- the empty list of theorems;
   622 
   623 
   624 *** HOL ***
   625 
   626 * HOL/MicroJava: formalization of a fragment of Java, together with a
   627 corresponding virtual machine and a specification of its bytecode
   628 verifier and a lightweight bytecode verifier, including proofs of
   629 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
   630 Cornelia Pusch (see also the homepage of project Bali at
   631 http://isabelle.in.tum.de/Bali/);
   632 
   633 * HOL/Algebra: new theory of rings and univariate polynomials, by
   634 Clemens Ballarin;
   635 
   636 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
   637 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
   638 Rasmussen;
   639 
   640 * HOL/Lattice: fundamental concepts of lattice theory and order
   641 structures, including duals, properties of bounds versus algebraic
   642 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
   643 Theorem for complete lattices etc.; may also serve as a demonstration
   644 for abstract algebraic reasoning using axiomatic type classes, and
   645 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
   646 
   647 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
   648 von Oheimb;
   649 
   650 * HOL/IMPP: extension of IMP with local variables and mutually
   651 recursive procedures, by David von Oheimb;
   652 
   653 * HOL/Lambda: converted into new-style theory and document;
   654 
   655 * HOL/ex/Multiquote: example of multiple nested quotations and
   656 anti-quotations -- basically a generalized version of de-Bruijn
   657 representation; very useful in avoiding lifting of operations;
   658 
   659 * HOL/record: added general record equality rule to simpset; fixed
   660 select-update simplification procedure to handle extended records as
   661 well; admit "r" as field name;
   662 
   663 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   664 other numeric types and also as the identity of groups, rings, etc.;
   665 
   666 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   667 Types nat and int belong to this axclass;
   668 
   669 * HOL: greatly improved simplification involving numerals of type nat, int, real:
   670    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   671    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   672   two terms #m*u and #n*u are replaced by #(m+n)*u
   673     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   674   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   675     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   676 
   677 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
   678 powerful prover for predicate logic but knows nothing of clasets; see
   679 ex/mesontest.ML and ex/mesontest2.ML for example applications;
   680 
   681 * HOL: new version of "case_tac" subsumes both boolean case split and
   682 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   683 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   684 
   685 * HOL: simplification no longer dives into case-expressions: only the
   686 selector expression is simplified, but not the remaining arms; to
   687 enable full simplification of case-expressions for datatype t, you may
   688 remove t.weak_case_cong from the simpset, either globally (Delcongs
   689 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
   690 
   691 * HOL/recdef: the recursion equations generated by 'recdef' for
   692 function 'f' are now called f.simps instead of f.rules; if all
   693 termination conditions are proved automatically, these simplification
   694 rules are added to the simpset, as in primrec; rules may be named
   695 individually as well, resulting in a separate list of theorems for
   696 each equation;
   697 
   698 * HOL/While is a new theory that provides a while-combinator. It
   699 permits the definition of tail-recursive functions without the
   700 provision of a termination measure. The latter is necessary once the
   701 invariant proof rule for while is applied.
   702 
   703 * HOL: new (overloaded) notation for the set of elements below/above
   704 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   705 
   706 * HOL: theorems impI, allI, ballI bound as "strip";
   707 
   708 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
   709 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   710 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   711 
   712 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   713 
   714 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
   715 main HOL, but was unused);
   716 
   717 * HOL: fewer consts declared as global (e.g. have to refer to
   718 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
   719 
   720 * HOL: tuned AST representation of nested pairs, avoiding bogus output
   721 in case of overlap with user translations (e.g. judgements over
   722 tuples); (note that the underlying logical represenation is still
   723 bogus);
   724 
   725 
   726 *** ZF ***
   727 
   728 * ZF: simplification automatically cancels common terms in arithmetic
   729 expressions over nat and int;
   730 
   731 * ZF: new treatment of nat to minimize type-checking: all operators
   732 coerce their operands to a natural number using the function natify,
   733 making the algebraic laws unconditional;
   734 
   735 * ZF: as above, for int: operators coerce their operands to an integer
   736 using the function intify;
   737 
   738 * ZF: the integer library now contains many of the usual laws for the
   739 orderings, including $<=, and monotonicity laws for $+ and $*;
   740 
   741 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
   742 simplification;
   743 
   744 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
   745 to the simplifier and classical reasoner simultaneously;
   746 
   747 
   748 *** General ***
   749 
   750 * Provers: blast_tac now handles actual object-logic rules as
   751 assumptions; note that auto_tac uses blast_tac internally as well;
   752 
   753 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
   754 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
   755 
   756 * Provers: delrules now handles destruct rules as well (no longer need
   757 explicit make_elim);
   758 
   759 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
   760   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   761 use instead the strong form,
   762   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
   763 in HOL, FOL and ZF the function cla_make_elim will create such rules
   764 from destruct-rules;
   765 
   766 * Provers: Simplifier.easy_setup provides a fast path to basic
   767 Simplifier setup for new object-logics;
   768 
   769 * Pure: AST translation rules no longer require constant head on LHS;
   770 
   771 * Pure: improved name spaces: ambiguous output is qualified; support
   772 for hiding of names;
   773 
   774 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
   775 XSYMBOL_HOME; no longer need to do manual configuration in most
   776 situations;
   777 
   778 * system: compression of ML heaps images may now be controlled via -c
   779 option of isabelle and isatool usedir (currently only observed by
   780 Poly/ML);
   781 
   782 * system: isatool installfonts may handle X-Symbol fonts as well (very
   783 useful for remote X11);
   784 
   785 * system: provide TAGS file for Isabelle sources;
   786 
   787 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
   788 order;
   789 
   790 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
   791 timing flag supersedes proof_timing and Toplevel.trace;
   792 
   793 * ML: new combinators |>> and |>>> for incremental transformations
   794 with secondary results (e.g. certain theory extensions):
   795 
   796 * ML: PureThy.add_defs gets additional argument to indicate potential
   797 overloading (usually false);
   798 
   799 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
   800 results;
   801 
   802 
   803 
   804 New in Isabelle99 (October 1999)
   805 --------------------------------
   806 
   807 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   808 
   809 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
   810 are no longer simplified.  (This allows the simplifier to unfold recursive
   811 functional programs.)  To restore the old behaviour, declare
   812 
   813     Delcongs [if_weak_cong];
   814 
   815 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
   816 complement;
   817 
   818 * HOL: the predicate "inj" is now defined by translation to "inj_on";
   819 
   820 * HOL/datatype: mutual_induct_tac no longer exists --
   821   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
   822 
   823 * HOL/typedef: fixed type inference for representing set; type
   824 arguments now have to occur explicitly on the rhs as type constraints;
   825 
   826 * ZF: The con_defs part of an inductive definition may no longer refer
   827 to constants declared in the same theory;
   828 
   829 * HOL, ZF: the function mk_cases, generated by the inductive
   830 definition package, has lost an argument.  To simplify its result, it
   831 uses the default simpset instead of a supplied list of theorems.
   832 
   833 * HOL/List: the constructors of type list are now Nil and Cons;
   834 
   835 * Simplifier: the type of the infix ML functions
   836         setSSolver addSSolver setSolver addSolver
   837 is now  simpset * solver -> simpset  where `solver' is a new abstract type
   838 for packaging solvers. A solver is created via
   839         mk_solver: string -> (thm list -> int -> tactic) -> solver
   840 where the string argument is only a comment.
   841 
   842 
   843 *** Proof tools ***
   844 
   845 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
   846 decision procedure for linear arithmetic. Currently it is used for
   847 types `nat', `int', and `real' in HOL (see below); it can, should and
   848 will be instantiated for other types and logics as well.
   849 
   850 * The simplifier now accepts rewrite rules with flexible heads, eg
   851      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
   852   They are applied like any rule with a non-pattern lhs, i.e. by first-order
   853   matching.
   854 
   855 
   856 *** General ***
   857 
   858 * New Isabelle/Isar subsystem provides an alternative to traditional
   859 tactical theorem proving; together with the ProofGeneral/isar user
   860 interface it offers an interactive environment for developing human
   861 readable proof documents (Isar == Intelligible semi-automated
   862 reasoning); for further information see isatool doc isar-ref,
   863 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
   864 
   865 * improved and simplified presentation of theories: better HTML markup
   866 (including colors), graph views in several sizes; isatool usedir now
   867 provides a proper interface for user theories (via -P option); actual
   868 document preparation based on (PDF)LaTeX is available as well (for
   869 new-style theories only); see isatool doc system for more information;
   870 
   871 * native support for Proof General, both for classic Isabelle and
   872 Isabelle/Isar;
   873 
   874 * ML function thm_deps visualizes dependencies of theorems and lemmas,
   875 using the graph browser tool;
   876 
   877 * Isabelle manuals now also available as PDF;
   878 
   879 * theory loader rewritten from scratch (may not be fully
   880 bug-compatible); old loadpath variable has been replaced by show_path,
   881 add_path, del_path, reset_path functions; new operations such as
   882 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
   883 isatool doc ref);
   884 
   885 * improved isatool install: option -k creates KDE application icon,
   886 option -p DIR installs standalone binaries;
   887 
   888 * added ML_PLATFORM setting (useful for cross-platform installations);
   889 more robust handling of platform specific ML images for SML/NJ;
   890 
   891 * the settings environment is now statically scoped, i.e. it is never
   892 created again in sub-processes invoked from isabelle, isatool, or
   893 Isabelle;
   894 
   895 * path element specification '~~' refers to '$ISABELLE_HOME';
   896 
   897 * in locales, the "assumes" and "defines" parts may be omitted if
   898 empty;
   899 
   900 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   901 long arrows);
   902 
   903 * new print_mode "HTML";
   904 
   905 * new flag show_tags controls display of tags of theorems (which are
   906 basically just comments that may be attached by some tools);
   907 
   908 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   909 mode and goal output format:
   910 
   911 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   912 244c244
   913 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   914 ---
   915 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   916 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   917 181c181
   918 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   919 ---
   920 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   921 
   922 * function bind_thms stores lists of theorems (cf. bind_thm);
   923 
   924 * new shorthand tactics ftac, eatac, datac, fatac;
   925 
   926 * qed (and friends) now accept "" as result name; in that case the
   927 theorem is not stored, but proper checks and presentation of the
   928 result still apply;
   929 
   930 * theorem database now also indexes constants "Trueprop", "all",
   931 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   932 
   933 
   934 *** HOL ***
   935 
   936 ** HOL arithmetic **
   937 
   938 * There are now decision procedures for linear arithmetic over nat and
   939 int:
   940 
   941 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   942 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   943 are treated as atomic; subformulae not involving type `nat' or `int'
   944 are ignored; quantified subformulae are ignored unless they are
   945 positive universal or negative existential. The tactic has to be
   946 invoked by hand and can be a little bit slow. In particular, the
   947 running time is exponential in the number of occurrences of `min' and
   948 `max', and `-' on `nat'.
   949 
   950 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   951 (negated) (in)equalities among the premises and the conclusion into
   952 account (i.e. no compound formulae) and does not know about `min' and
   953 `max', and `-' on `nat'. It is fast and is used automatically by the
   954 simplifier.
   955 
   956 NB: At the moment, these decision procedures do not cope with mixed
   957 nat/int formulae where the two parts interact, such as `m < n ==>
   958 int(m) < int(n)'.
   959 
   960 * HOL/Numeral provides a generic theory of numerals (encoded
   961 efficiently as bit strings); setup for types nat/int/real is in place;
   962 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   963 int, existing theories and proof scripts may require a few additional
   964 type constraints;
   965 
   966 * integer division and remainder can now be performed on constant
   967 arguments;
   968 
   969 * many properties of integer multiplication, division and remainder
   970 are now available;
   971 
   972 * An interface to the Stanford Validity Checker (SVC) is available through the
   973 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   974 are proved automatically.  SVC must be installed separately, and its results
   975 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   976 invocation of the underlying oracle).  For SVC see
   977   http://verify.stanford.edu/SVC
   978 
   979 * IsaMakefile: the HOL-Real target now builds an actual image;
   980 
   981 
   982 ** HOL misc **
   983 
   984 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   985 (in Isabelle/Isar) -- by Gertrud Bauer;
   986 
   987 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   988 analysis for assembly languages with subtypes;
   989 
   990 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   991 -- avoids syntactic ambiguities and treats state, transition, and
   992 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   993 changed syntax and (many) tactics;
   994 
   995 * HOL/inductive: Now also handles more general introduction rules such
   996   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
   997   theorems are now maintained within the theory (maintained via the
   998   "mono" attribute);
   999 
  1000 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1001   (using function types) such as
  1002 
  1003   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1004 
  1005 * HOL/record: record_simproc (part of the default simpset) takes care
  1006 of selectors applied to updated records; record_split_tac is no longer
  1007 part of the default claset; update_defs may now be removed from the
  1008 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1009 
  1010   claset_ref () := claset() addSWrapper record_split_wrapper;
  1011   Delsimprocs [record_simproc]
  1012 
  1013 * HOL/typedef: fixed type inference for representing set; type
  1014 arguments now have to occur explicitly on the rhs as type constraints;
  1015 
  1016 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1017 names rather than an ML expression;
  1018 
  1019 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1020 supplied later.  Program schemes can be defined, such as
  1021     "While B C s = (if B s then While B C (C s) else s)"
  1022 where the well-founded relation can be chosen after B and C have been given.
  1023 
  1024 * HOL/List: the constructors of type list are now Nil and Cons;
  1025 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1026 course, ML tools referring to List.list.op # etc. have to be adapted;
  1027 
  1028 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1029 disabled by default; run isabelle with option -m HOL to get back to
  1030 the original Gordon/HOL-style output;
  1031 
  1032 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1033 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1034 
  1035 * HOL basic syntax simplified (more orthogonal): all variants of
  1036 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1037 Eps operator is provided as well: "SOME x. P[x]";
  1038 
  1039 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1040 
  1041 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1042 thus available for user theories;
  1043 
  1044 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1045 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1046 time;
  1047 
  1048 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1049 several times and then mp;
  1050 
  1051 
  1052 *** LK ***
  1053 
  1054 * the notation <<...>> is now available as a notation for sequences of
  1055 formulas;
  1056 
  1057 * the simplifier is now installed
  1058 
  1059 * the axiom system has been generalized (thanks to Soren Heilmann)
  1060 
  1061 * the classical reasoner now has a default rule database
  1062 
  1063 
  1064 *** ZF ***
  1065 
  1066 * new primrec section allows primitive recursive functions to be given
  1067 directly (as in HOL) over datatypes and the natural numbers;
  1068 
  1069 * new tactics induct_tac and exhaust_tac for induction (or case
  1070 analysis) over datatypes and the natural numbers;
  1071 
  1072 * the datatype declaration of type T now defines the recursor T_rec;
  1073 
  1074 * simplification automatically does freeness reasoning for datatype
  1075 constructors;
  1076 
  1077 * automatic type-inference, with AddTCs command to insert new
  1078 type-checking rules;
  1079 
  1080 * datatype introduction rules are now added as Safe Introduction rules
  1081 to the claset;
  1082 
  1083 * the syntax "if P then x else y" is now available in addition to
  1084 if(P,x,y);
  1085 
  1086 
  1087 *** Internal programming interfaces ***
  1088 
  1089 * tuned simplifier trace output; new flag debug_simp;
  1090 
  1091 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1092 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1093 
  1094 * AxClass.axclass_tac lost the theory argument;
  1095 
  1096 * tuned current_goals_markers semantics: begin / end goal avoids
  1097 printing empty lines;
  1098 
  1099 * removed prs and prs_fn hook, which was broken because it did not
  1100 include \n in its semantics, forcing writeln to add one
  1101 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1102 string -> unit if you really want to output text without newline;
  1103 
  1104 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1105 plain output, interface builders may have to enable 'isabelle_font'
  1106 mode to get Isabelle font glyphs as before;
  1107 
  1108 * refined token_translation interface; INCOMPATIBILITY: output length
  1109 now of type real instead of int;
  1110 
  1111 * theory loader actions may be traced via new ThyInfo.add_hook
  1112 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1113 your own database of information attached to *whole* theories -- as
  1114 opposed to intra-theory data slots offered via TheoryDataFun;
  1115 
  1116 * proper handling of dangling sort hypotheses (at last!);
  1117 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1118 extra sort hypotheses that can be witnessed from the type signature;
  1119 the force_strip_shyps flag is gone, any remaining shyps are simply
  1120 left in the theorem (with a warning issued by strip_shyps_warning);
  1121 
  1122 
  1123 
  1124 New in Isabelle98-1 (October 1998)
  1125 ----------------------------------
  1126 
  1127 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1128 
  1129 * several changes of automated proof tools;
  1130 
  1131 * HOL: major changes to the inductive and datatype packages, including
  1132 some minor incompatibilities of theory syntax;
  1133 
  1134 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1135 called `inj_on';
  1136 
  1137 * HOL: removed duplicate thms in Arith:
  1138   less_imp_add_less  should be replaced by  trans_less_add1
  1139   le_imp_add_le      should be replaced by  trans_le_add1
  1140 
  1141 * HOL: unary minus is now overloaded (new type constraints may be
  1142 required);
  1143 
  1144 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1145 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1146 now taken as an integer constant.
  1147 
  1148 * Pure: ML function 'theory_of' renamed to 'theory';
  1149 
  1150 
  1151 *** Proof tools ***
  1152 
  1153 * Simplifier:
  1154   1. Asm_full_simp_tac is now more aggressive.
  1155      1. It will sometimes reorient premises if that increases their power to
  1156         simplify.
  1157      2. It does no longer proceed strictly from left to right but may also
  1158         rotate premises to achieve further simplification.
  1159      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1160      old Asm_full_simp_tac in that it does not rotate premises.
  1161   2. The simplifier now knows a little bit about nat-arithmetic.
  1162 
  1163 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1164 allows for selected deletion of wrappers, by introduction of names for
  1165 wrapper functionals.  This implies that addbefore, addSbefore,
  1166 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1167 and that adding two tactics with the same name overwrites the first
  1168 one (emitting a warning).
  1169   type wrapper = (int -> tactic) -> (int -> tactic)
  1170   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1171   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1172   delWrapper, delSWrapper: claset *  string            -> claset
  1173   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1174 
  1175 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1176 semantics; addbefore now affects only the unsafe part of step_tac
  1177 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1178 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1179 by Force_tac;
  1180 
  1181 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1182 compWrapper; added safe wrapper (and access functions for it);
  1183 
  1184 * HOL/split_all_tac is now much faster and fails if there is nothing
  1185 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1186 and the names of the automatically generated variables have changed.
  1187 split_all_tac has moved within claset() from unsafe wrappers to safe
  1188 wrappers, which means that !!-bound variables are split much more
  1189 aggressively, and safe_tac and clarify_tac now split such variables.
  1190 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1191 Note: the same holds for record_split_tac, which does the job of
  1192 split_all_tac for record fields.
  1193 
  1194 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1195 permanently to the default simpset using Addsplits just like
  1196 Addsimps. They can be removed via Delsplits just like
  1197 Delsimps. Lower-case versions are also available.
  1198 
  1199 * HOL/Simplifier: The rule split_if is now part of the default
  1200 simpset. This means that the simplifier will eliminate all occurrences
  1201 of if-then-else in the conclusion of a goal. To prevent this, you can
  1202 either remove split_if completely from the default simpset by
  1203 `Delsplits [split_if]' or remove it in a specific call of the
  1204 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1205 other case splitting rules to/from the default simpset: every datatype
  1206 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1207 t is the name of the datatype).
  1208 
  1209 * Classical reasoner / Simplifier combination: new force_tac (and
  1210 derivatives Force_tac, force) combines rewriting and classical
  1211 reasoning (and whatever other tools) similarly to auto_tac, but is
  1212 aimed to solve the given subgoal completely.
  1213 
  1214 
  1215 *** General ***
  1216 
  1217 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1218 and `goalw': the theory is no longer needed as an explicit argument -
  1219 the current theory context is used; assumptions are no longer returned
  1220 at the ML-level unless one of them starts with ==> or !!; it is
  1221 recommended to convert to these new commands using isatool fixgoal
  1222 (backup your sources first!);
  1223 
  1224 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1225 the current theory context, and 'theory' to lookup stored theories;
  1226 
  1227 * new theory section 'locale' for declaring constants, assumptions and
  1228 definitions that have local scope;
  1229 
  1230 * new theory section 'nonterminals' for purely syntactic types;
  1231 
  1232 * new theory section 'setup' for generic ML setup functions
  1233 (e.g. package initialization);
  1234 
  1235 * the distribution now includes Isabelle icons: see
  1236 lib/logo/isabelle-{small,tiny}.xpm;
  1237 
  1238 * isatool install - install binaries with absolute references to
  1239 ISABELLE_HOME/bin;
  1240 
  1241 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1242 
  1243 * print mode 'emacs' reserved for Isamode;
  1244 
  1245 * support multiple print (ast) translations per constant name;
  1246 
  1247 * theorems involving oracles are now printed with a suffixed [!];
  1248 
  1249 
  1250 *** HOL ***
  1251 
  1252 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1253 
  1254 * HOL/inductive package reorganized and improved: now supports mutual
  1255 definitions such as
  1256 
  1257   inductive EVEN ODD
  1258     intrs
  1259       null "0 : EVEN"
  1260       oddI "n : EVEN ==> Suc n : ODD"
  1261       evenI "n : ODD ==> Suc n : EVEN"
  1262 
  1263 new theorem list "elims" contains an elimination rule for each of the
  1264 recursive sets; inductive definitions now handle disjunctive premises
  1265 correctly (also ZF);
  1266 
  1267 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1268 "mutual_induct" no longer exists - the induction rule is always
  1269 contained in "induct";
  1270 
  1271 
  1272 * HOL/datatype package re-implemented and greatly improved: now
  1273 supports mutually recursive datatypes such as
  1274 
  1275   datatype
  1276     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1277             | SUM ('a aexp) ('a aexp)
  1278             | DIFF ('a aexp) ('a aexp)
  1279             | NUM 'a
  1280   and
  1281     'a bexp = LESS ('a aexp) ('a aexp)
  1282             | AND ('a bexp) ('a bexp)
  1283             | OR ('a bexp) ('a bexp)
  1284 
  1285 as well as indirectly recursive datatypes such as
  1286 
  1287   datatype
  1288     ('a, 'b) term = Var 'a
  1289                   | App 'b ((('a, 'b) term) list)
  1290 
  1291 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1292 induction on mutually / indirectly recursive datatypes.
  1293 
  1294 Primrec equations are now stored in theory and can be accessed via
  1295 <function_name>.simps.
  1296 
  1297 INCOMPATIBILITIES:
  1298 
  1299   - Theories using datatypes must now have theory Datatype as an
  1300     ancestor.
  1301   - The specific <typename>.induct_tac no longer exists - use the
  1302     generic induct_tac instead.
  1303   - natE has been renamed to nat.exhaust - use exhaust_tac
  1304     instead of res_inst_tac ... natE. Note that the variable
  1305     names in nat.exhaust differ from the names in natE, this
  1306     may cause some "fragile" proofs to fail.
  1307   - The theorems split_<typename>_case and split_<typename>_case_asm
  1308     have been renamed to <typename>.split and <typename>.split_asm.
  1309   - Since default sorts of type variables are now handled correctly,
  1310     some datatype definitions may have to be annotated with explicit
  1311     sort constraints.
  1312   - Primrec definitions no longer require function name and type
  1313     of recursive argument.
  1314 
  1315 Consider using isatool fixdatatype to adapt your theories and proof
  1316 scripts to the new package (backup your sources first!).
  1317 
  1318 
  1319 * HOL/record package: considerably improved implementation; now
  1320 includes concrete syntax for record types, terms, updates; theorems
  1321 for surjective pairing and splitting !!-bound record variables; proof
  1322 support is as follows:
  1323 
  1324   1) standard conversions (selectors or updates applied to record
  1325 constructor terms) are part of the standard simpset;
  1326 
  1327   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1328 made part of standard simpset and claset via addIffs;
  1329 
  1330   3) a tactic for record field splitting (record_split_tac) is part of
  1331 the standard claset (addSWrapper);
  1332 
  1333 To get a better idea about these rules you may retrieve them via
  1334 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1335 the name of your record type.
  1336 
  1337 The split tactic 3) conceptually simplifies by the following rule:
  1338 
  1339   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1340 
  1341 Thus any record variable that is bound by meta-all will automatically
  1342 blow up into some record constructor term, consequently the
  1343 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1344 solve record problems automatically.
  1345 
  1346 
  1347 * reorganized the main HOL image: HOL/Integ and String loaded by
  1348 default; theory Main includes everything;
  1349 
  1350 * automatic simplification of integer sums and comparisons, using cancellation;
  1351 
  1352 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1353 
  1354 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1355 
  1356 * many new identities for unions, intersections, set difference, etc.;
  1357 
  1358 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1359 called split_if, split_split, split_sum_case and split_nat_case (to go
  1360 with add/delsplits);
  1361 
  1362 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1363 (?x::unit) = (); this is made part of the default simpset, which COULD
  1364 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1365 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1366 unit_abs_eta_conv is added in order to counter the effect of
  1367 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1368 %u.f();
  1369 
  1370 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1371 makes more sense);
  1372 
  1373 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1374   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1375   disjointness reasoning but breaking a few old proofs.
  1376 
  1377 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1378 to 'converse' from 'inverse' (for compatibility with ZF and some
  1379 literature);
  1380 
  1381 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1382 the well-founded relation;
  1383 
  1384 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1385     Compl A.  The "Compl" syntax remains available as input syntax for this
  1386     release ONLY.
  1387 
  1388 * HOL/Update: new theory of function updates:
  1389     f(a:=b) == %x. if x=a then b else f x
  1390 may also be iterated as in f(a:=b,c:=d,...);
  1391 
  1392 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1393 
  1394 * HOL/List:
  1395   - new function list_update written xs[i:=v] that updates the i-th
  1396     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1397   - new function `upt' written [i..j(] which generates the list
  1398     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1399     bound write [i..j], which is a shorthand for [i..j+1(].
  1400   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1401 
  1402 * HOL/Arith:
  1403   - removed 'pred' (predecessor) function;
  1404   - generalized some theorems about n-1;
  1405   - many new laws about "div" and "mod";
  1406   - new laws about greatest common divisors (see theory ex/Primes);
  1407 
  1408 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1409 instead of "inverse";
  1410 
  1411 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1412   of the multiset ordering;
  1413 
  1414 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1415   (not included by default);
  1416 
  1417 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1418 
  1419 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1420   programs, i.e. different program variables may have different types.
  1421 
  1422 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1423   [previously, this check worked only if the rewrite rule was unconditional]
  1424   Now rew can involve either definitions or equalities (either == or =).
  1425 
  1426 
  1427 *** ZF ***
  1428 
  1429 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  1430   only the theorems proved on ZF.ML;
  1431 
  1432 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1433   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1434   disjointness reasoning but breaking a few old proofs.
  1435 
  1436 * ZF/Update: new theory of function updates
  1437     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  1438   may also be iterated as in f(a:=b,c:=d,...);
  1439 
  1440 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1441 
  1442 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1443   [previously, this check worked only if the rewrite rule was unconditional]
  1444   Now rew can involve either definitions or equalities (either == or =).
  1445 
  1446 * case_tac provided for compatibility with HOL
  1447     (like the old excluded_middle_tac, but with subgoals swapped)
  1448 
  1449 
  1450 *** Internal programming interfaces ***
  1451 
  1452 * Pure: several new basic modules made available for general use, see
  1453 also src/Pure/README;
  1454 
  1455 * improved the theory data mechanism to support encapsulation (data
  1456 kind name replaced by private Object.kind, acting as authorization
  1457 key); new type-safe user interface via functor TheoryDataFun; generic
  1458 print_data function becomes basically useless;
  1459 
  1460 * removed global_names compatibility flag -- all theory declarations
  1461 are qualified by default;
  1462 
  1463 * module Pure/Syntax now offers quote / antiquote translation
  1464 functions (useful for Hoare logic etc. with implicit dependencies);
  1465 see HOL/ex/Antiquote for an example use;
  1466 
  1467 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1468 cterm -> thm;
  1469 
  1470 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1471 subgoal;
  1472 
  1473 * Display.print_goals function moved to Locale.print_goals;
  1474 
  1475 * standard print function for goals supports current_goals_markers
  1476 variable for marking begin of proof, end of proof, start of goal; the
  1477 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1478 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1479 for example;
  1480 
  1481 
  1482 
  1483 New in Isabelle98 (January 1998)
  1484 --------------------------------
  1485 
  1486 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1487 
  1488 * changed lexical syntax of terms / types: dots made part of long
  1489 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1490 
  1491 * simpset (and claset) reference variable replaced by functions
  1492 simpset / simpset_ref;
  1493 
  1494 * no longer supports theory aliases (via merge) and non-trivial
  1495 implicit merge of thms' signatures;
  1496 
  1497 * most internal names of constants changed due to qualified names;
  1498 
  1499 * changed Pure/Sequence interface (see Pure/seq.ML);
  1500 
  1501 
  1502 *** General Changes ***
  1503 
  1504 * hierachically structured name spaces (for consts, types, axms, thms
  1505 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1506 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1507 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1508 long_names for fully qualified output names; NOTE: ML programs
  1509 (special tactics, packages etc.) referring to internal names may have
  1510 to be adapted to cope with fully qualified names; in case of severe
  1511 backward campatibility problems try setting 'global_names' at compile
  1512 time to have enrything declared within a flat name space; one may also
  1513 fine tune name declarations in theories via the 'global' and 'local'
  1514 section;
  1515 
  1516 * reimplemented the implicit simpset and claset using the new anytype
  1517 data filed in signatures; references simpset:simpset ref etc. are
  1518 replaced by functions simpset:unit->simpset and
  1519 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1520 to patch your ML files accordingly;
  1521 
  1522 * HTML output now includes theory graph data for display with Java
  1523 applet or isatool browser; data generated automatically via isatool
  1524 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1525 
  1526 * defs may now be conditional; improved rewrite_goals_tac to handle
  1527 conditional equations;
  1528 
  1529 * defs now admits additional type arguments, using TYPE('a) syntax;
  1530 
  1531 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1532 creates a new theory node; implicit merge of thms' signatures is
  1533 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1534 transfer:theory->thm->thm in (rare) cases;
  1535 
  1536 * improved handling of draft signatures / theories; draft thms (and
  1537 ctyps, cterms) are automatically promoted to real ones;
  1538 
  1539 * slightly changed interfaces for oracles: admit many per theory, named
  1540 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1541 
  1542 * print_goals: optional output of const types (set show_consts and
  1543 show_types);
  1544 
  1545 * improved output of warnings (###) and errors (***);
  1546 
  1547 * subgoal_tac displays a warning if the new subgoal has type variables;
  1548 
  1549 * removed old README and Makefiles;
  1550 
  1551 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1552 
  1553 * removed obsolete init_pps and init_database;
  1554 
  1555 * deleted the obsolete tactical STATE, which was declared by
  1556     fun STATE tacfun st = tacfun st st;
  1557 
  1558 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1559 (which abbreviates $HOME);
  1560 
  1561 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1562 use isatool fixseq to adapt your ML programs (this works for fully
  1563 qualified references to the Sequence structure only!);
  1564 
  1565 * use_thy no longer requires writable current directory; it always
  1566 reloads .ML *and* .thy file, if either one is out of date;
  1567 
  1568 
  1569 *** Classical Reasoner ***
  1570 
  1571 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1572 tactics that use classical reasoning to simplify a subgoal without
  1573 splitting it into several subgoals;
  1574 
  1575 * Safe_tac: like safe_tac but uses the default claset;
  1576 
  1577 
  1578 *** Simplifier ***
  1579 
  1580 * added simplification meta rules:
  1581     (asm_)(full_)simplify: simpset -> thm -> thm;
  1582 
  1583 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1584 logics (again);
  1585 
  1586 * added prems argument to simplification procedures;
  1587 
  1588 * HOL, FOL, ZF: added infix function `addsplits':
  1589   instead of `<simpset> setloop (split_tac <thms>)'
  1590   you can simply write `<simpset> addsplits <thms>'
  1591 
  1592 
  1593 *** Syntax ***
  1594 
  1595 * TYPE('a) syntax for type reflection terms;
  1596 
  1597 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1598 
  1599 * pretty printer: changed order of mixfix annotation preference (again!);
  1600 
  1601 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1602 
  1603 
  1604 *** HOL ***
  1605 
  1606 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1607   with `addloop' of the simplifier to faciliate case splitting in premises.
  1608 
  1609 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1610 
  1611 * HOL/Auth: new protocol proofs including some for the Internet
  1612   protocol TLS;
  1613 
  1614 * HOL/Map: new theory of `maps' a la VDM;
  1615 
  1616 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1617 cancelling out common nat summands from =, <, <= (in)equalities, or
  1618 differences; simplification procedures nat_cancel_factor for
  1619 cancelling common factor from =, <, <= (in)equalities over natural
  1620 sums; nat_cancel contains both kinds of procedures, it is installed by
  1621 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1622 
  1623 * HOL/simplifier: terms of the form
  1624   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1625   are rewritten to
  1626   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1627   and those of the form
  1628   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1629   are rewritten to
  1630   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1631 
  1632 * HOL/datatype
  1633   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1634 
  1635   P(t_case f1 ... fn x) =
  1636      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1637         ...
  1638        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1639      )
  1640 
  1641   and a theorem `split_t_case_asm' of the form
  1642 
  1643   P(t_case f1 ... fn x) =
  1644     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1645         ...
  1646        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1647      )
  1648   which can be added to a simpset via `addsplits'. The existing theorems
  1649   expand_list_case and expand_option_case have been renamed to
  1650   split_list_case and split_option_case.
  1651 
  1652 * HOL/Arithmetic:
  1653   - `pred n' is automatically converted to `n-1'.
  1654     Users are strongly encouraged not to use `pred' any longer,
  1655     because it will disappear altogether at some point.
  1656   - Users are strongly encouraged to write "0 < n" rather than
  1657     "n ~= 0". Theorems and proof tools have been modified towards this
  1658     `standard'.
  1659 
  1660 * HOL/Lists:
  1661   the function "set_of_list" has been renamed "set" (and its theorems too);
  1662   the function "nth" now takes its arguments in the reverse order and
  1663   has acquired the infix notation "!" as in "xs!n".
  1664 
  1665 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1666 
  1667 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1668   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1669 
  1670 * HOL/record: extensible records with schematic structural subtyping
  1671 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1672 still lacks various theorems and concrete record syntax;
  1673 
  1674 
  1675 *** HOLCF ***
  1676 
  1677 * removed "axioms" and "generated by" sections;
  1678 
  1679 * replaced "ops" section by extended "consts" section, which is capable of
  1680   handling the continuous function space "->" directly;
  1681 
  1682 * domain package:
  1683   . proves theorems immediately and stores them in the theory,
  1684   . creates hierachical name space,
  1685   . now uses normal mixfix annotations (instead of cinfix...),
  1686   . minor changes to some names and values (for consistency),
  1687   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1688   . separator between mutual domain defs: changed "," to "and",
  1689   . improved handling of sort constraints;  now they have to
  1690     appear on the left-hand side of the equations only;
  1691 
  1692 * fixed LAM <x,y,zs>.b syntax;
  1693 
  1694 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1695 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1696 
  1697 
  1698 *** FOL and ZF ***
  1699 
  1700 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1701   with `addloop' of the simplifier to faciliate case splitting in premises.
  1702 
  1703 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1704 in HOL, they strip ALL and --> from proved theorems;
  1705 
  1706 
  1707 
  1708 New in Isabelle94-8 (May 1997)
  1709 ------------------------------
  1710 
  1711 *** General Changes ***
  1712 
  1713 * new utilities to build / run / maintain Isabelle etc. (in parts
  1714 still somewhat experimental); old Makefiles etc. still functional;
  1715 
  1716 * new 'Isabelle System Manual';
  1717 
  1718 * INSTALL text, together with ./configure and ./build scripts;
  1719 
  1720 * reimplemented type inference for greater efficiency, better error
  1721 messages and clean internal interface;
  1722 
  1723 * prlim command for dealing with lots of subgoals (an easier way of
  1724 setting goals_limit);
  1725 
  1726 
  1727 *** Syntax ***
  1728 
  1729 * supports alternative (named) syntax tables (parser and pretty
  1730 printer); internal interface is provided by add_modesyntax(_i);
  1731 
  1732 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1733 be used in conjunction with the Isabelle symbol font; uses the
  1734 "symbols" syntax table;
  1735 
  1736 * added token_translation interface (may translate name tokens in
  1737 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1738 the current print_mode); IMPORTANT: user print translation functions
  1739 are responsible for marking newly introduced bounds
  1740 (Syntax.mark_boundT);
  1741 
  1742 * token translations for modes "xterm" and "xterm_color" that display
  1743 names in bold, underline etc. or colors (which requires a color
  1744 version of xterm);
  1745 
  1746 * infixes may now be declared with names independent of their syntax;
  1747 
  1748 * added typed_print_translation (like print_translation, but may
  1749 access type of constant);
  1750 
  1751 
  1752 *** Classical Reasoner ***
  1753 
  1754 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  1755 some limitations.  Blast_tac...
  1756   + ignores addss, addbefore, addafter; this restriction is intrinsic
  1757   + ignores elimination rules that don't have the correct format
  1758         (the conclusion MUST be a formula variable)
  1759   + ignores types, which can make HOL proofs fail
  1760   + rules must not require higher-order unification, e.g. apply_type in ZF
  1761     [message "Function Var's argument not a bound variable" relates to this]
  1762   + its proof strategy is more general but can actually be slower
  1763 
  1764 * substitution with equality assumptions no longer permutes other
  1765 assumptions;
  1766 
  1767 * minor changes in semantics of addafter (now called addaltern); renamed
  1768 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  1769 (and access functions for it);
  1770 
  1771 * improved combination of classical reasoner and simplifier:
  1772   + functions for handling clasimpsets
  1773   + improvement of addss: now the simplifier is called _after_ the
  1774     safe steps.
  1775   + safe variant of addss called addSss: uses safe simplifications
  1776     _during_ the safe steps. It is more complete as it allows multiple
  1777     instantiations of unknowns (e.g. with slow_tac).
  1778 
  1779 *** Simplifier ***
  1780 
  1781 * added interface for simplification procedures (functions that
  1782 produce *proven* rewrite rules on the fly, depending on current
  1783 redex);
  1784 
  1785 * ordering on terms as parameter (used for ordered rewriting);
  1786 
  1787 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  1788 
  1789 * the solver is now split into a safe and an unsafe part.
  1790 This should be invisible for the normal user, except that the
  1791 functions setsolver and addsolver have been renamed to setSolver and
  1792 addSolver; added safe_asm_full_simp_tac;
  1793 
  1794 
  1795 *** HOL ***
  1796 
  1797 * a generic induction tactic `induct_tac' which works for all datatypes and
  1798 also for type `nat';
  1799 
  1800 * a generic case distinction tactic `exhaust_tac' which works for all
  1801 datatypes and also for type `nat';
  1802 
  1803 * each datatype comes with a function `size';
  1804 
  1805 * patterns in case expressions allow tuple patterns as arguments to
  1806 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1807 
  1808 * primrec now also works with type nat;
  1809 
  1810 * recdef: a new declaration form, allows general recursive functions to be
  1811 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1812 
  1813 * the constant for negation has been renamed from "not" to "Not" to
  1814 harmonize with FOL, ZF, LK, etc.;
  1815 
  1816 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1817 infinite lists;
  1818 
  1819 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1820 
  1821 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1822 problems in commutative rings, using axiomatic type classes for + and *;
  1823 
  1824 * more examples in HOL/MiniML and HOL/Auth;
  1825 
  1826 * more default rewrite rules for quantifiers, union/intersection;
  1827 
  1828 * a new constant `arbitrary == @x.False';
  1829 
  1830 * HOLCF/IOA replaces old HOL/IOA;
  1831 
  1832 * HOLCF changes: derived all rules and arities
  1833   + axiomatic type classes instead of classes
  1834   + typedef instead of faking type definitions
  1835   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1836   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1837   + eliminated the types void, one, tr
  1838   + use unit lift and bool lift (with translations) instead of one and tr
  1839   + eliminated blift from Lift3.thy (use Def instead of blift)
  1840   all eliminated rules are derived as theorems --> no visible changes ;
  1841 
  1842 
  1843 *** ZF ***
  1844 
  1845 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1846 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1847 as ZF_cs addSIs [equalityI];
  1848 
  1849 
  1850 
  1851 New in Isabelle94-7 (November 96)
  1852 ---------------------------------
  1853 
  1854 * allowing negative levels (as offsets) in prlev and choplev;
  1855 
  1856 * super-linear speedup for large simplifications;
  1857 
  1858 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1859 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1860 FAIL); can suppress it using the command Delsimps (ex_simps @
  1861 all_simps); De Morgan laws are also now included, by default;
  1862 
  1863 * improved printing of ==>  :  ~:
  1864 
  1865 * new object-logic "Sequents" adds linear logic, while replacing LK
  1866 and Modal (thanks to Sara Kalvala);
  1867 
  1868 * HOL/Auth: correctness proofs for authentication protocols;
  1869 
  1870 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1871 examples on HOL/Auth);
  1872 
  1873 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1874 the rewriter and classical reasoner simultaneously;
  1875 
  1876 * function uresult no longer returns theorems in "standard" format;
  1877 regain previous version by: val uresult = standard o uresult;
  1878 
  1879 
  1880 
  1881 New in Isabelle94-6
  1882 -------------------
  1883 
  1884 * oracles -- these establish an interface between Isabelle and trusted
  1885 external reasoners, which may deliver results as theorems;
  1886 
  1887 * proof objects (in particular record all uses of oracles);
  1888 
  1889 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1890 
  1891 * "constdefs" section in theory files;
  1892 
  1893 * "primrec" section (HOL) no longer requires names;
  1894 
  1895 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1896 
  1897 
  1898 
  1899 New in Isabelle94-5
  1900 -------------------
  1901 
  1902 * reduced space requirements;
  1903 
  1904 * automatic HTML generation from theories;
  1905 
  1906 * theory files no longer require "..." (quotes) around most types;
  1907 
  1908 * new examples, including two proofs of the Church-Rosser theorem;
  1909 
  1910 * non-curried (1994) version of HOL is no longer distributed;
  1911 
  1912 
  1913 
  1914 New in Isabelle94-4
  1915 -------------------
  1916 
  1917 * greatly reduced space requirements;
  1918 
  1919 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1920 
  1921 * searchable theorem database (see the section "Retrieving theorems" on
  1922 page 8 of the Reference Manual);
  1923 
  1924 * new examples, including Grabczewski's monumental case study of the
  1925 Axiom of Choice;
  1926 
  1927 * The previous version of HOL renamed to Old_HOL;
  1928 
  1929 * The new version of HOL (previously called CHOL) uses a curried syntax
  1930 for functions.  Application looks like f a b instead of f(a,b);
  1931 
  1932 * Mutually recursive inductive definitions finally work in HOL;
  1933 
  1934 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1935 translates to the operator "split";
  1936 
  1937 
  1938 
  1939 New in Isabelle94-3
  1940 -------------------
  1941 
  1942 * new infix operator, addss, allowing the classical reasoner to
  1943 perform simplification at each step of its search.  Example:
  1944         fast_tac (cs addss ss)
  1945 
  1946 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1947 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1948 look like (a,b) instead of <a,b>;
  1949 
  1950 * PLEASE NOTE: CHOL will eventually replace HOL!
  1951 
  1952 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1953 It translates to the operator "split".  A new theory of integers is available;
  1954 
  1955 * In ZF, integer numerals now denote two's-complement binary integers.
  1956 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1957 
  1958 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1959 of the Axiom of Choice;
  1960 
  1961 
  1962 
  1963 New in Isabelle94-2
  1964 -------------------
  1965 
  1966 * Significantly faster resolution;
  1967 
  1968 * the different sections in a .thy file can now be mixed and repeated
  1969 freely;
  1970 
  1971 * Database of theorems for FOL, HOL and ZF.  New
  1972 commands including qed, qed_goal and bind_thm store theorems in the database.
  1973 
  1974 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1975 a given theory (thms_of), or find out what theory a theorem was proved in
  1976 (theory_of_thm);
  1977 
  1978 * Bugs fixed in the inductive definition and datatype packages;
  1979 
  1980 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1981 and HOL_dup_cs obsolete;
  1982 
  1983 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1984 have been removed;
  1985 
  1986 * Simpler definition of function space in ZF;
  1987 
  1988 * new results about cardinal and ordinal arithmetic in ZF;
  1989 
  1990 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1991 types;
  1992 
  1993 
  1994 $Id$