NEWS
author paulson
Fri Aug 11 13:27:17 2000 +0200 (2000-08-11)
changeset 9578 ab26d6c8ebfe
parent 9577 9e66e8ed8237
child 9612 e6ba17cd012e
permissions -rw-r--r--
new theory Integ/IntDiv and many more monotonicity laws, etc., for the integers
     1 
     2 Isabelle NEWS -- history user-relevant changes
     3 ==============================================
     4 
     5 New in this Isabelle version
     6 ----------------------------
     7 
     8 *** Overview of INCOMPATIBILITIES (see below for more details) ***
     9 
    10 * HOL: simplification of natural numbers is much changed; to partly
    11 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
    12 issue the following ML commands:
    13 
    14   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
    15   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
    16 
    17 * HOL: 0 is now overloaded, so the type constraint ::nat may sometimes be
    18 needed;
    19 
    20 * HOL: the constant for f``x is now "image" rather than "op ``";
    21 
    22 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
    23 product is now "<*>" instead of "Times"; the lexicographic product is
    24 now "<*lex*>" instead of "**";
    25 
    26 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
    27 
    28 * HOL: simplification no longer dives into case-expressions;
    29 
    30 * HOL: the recursion equations generated by 'recdef' are now called
    31 f.simps instead of f.rules;
    32 
    33 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
    34 main HOL, but was unused); should better use HOL's datatype package
    35 anyway;
    36 
    37 * HOL: removed obsolete theorem binding expand_if (refer to split_if
    38 instead);
    39 
    40 * HOL/Real: "rabs" replaced by overloaded "abs" function;
    41 
    42 * HOL/ML: even fewer consts are declared as global (see theories Ord,
    43 Lfp, Gfp, WF); this only affects ML packages that refer to const names
    44 internally;
    45 
    46 * HOL, ZF: syntax for quotienting wrt an equivalence relation changed from
    47   A/r to A//r;
    48 
    49 * ZF: new treatment of arithmetic (nat & int) may break some old proofs;
    50 
    51 * Isar/Provers: intro/elim/dest attributes: changed
    52 intro/intro!/intro!!  flags to intro!/intro/intro? (in most cases, one
    53 should have to change intro!! to intro? only);
    54 
    55 * Isar: changed syntax of local blocks from {{ }} to { };
    56 
    57 * Provers: strengthened force_tac by using new first_best_tac;
    58 
    59 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
    60   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
    61 use instead the strong form,
    62   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
    63 In HOL, FOL and ZF the function cla_make_elim will create such rules
    64 from destruct-rules;
    65 
    66 * Provers: safe_asm_full_simp_tac is no longer in the simplifier signature. Use
    67   val safe_asm_full_simp_tac = generic_simp_tac true (true,true,true);
    68   if required.
    69 
    70 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
    71 timing flag supersedes proof_timing and Toplevel.trace;
    72 
    73 * ML: PureThy.add_thms/add_axioms/add_defs return theorems as well;
    74 
    75 * ML: PureThy.add_defs gets additional argument to indicate potential
    76 overloading (usually false);
    77 
    78 * LaTeX: several changes of isabelle.sty;
    79 
    80 
    81 *** Document preparation ***
    82 
    83 * formal comments (text blocks etc.) in new-style theories may now
    84 contain antiquotations of thm/prop/term/typ to be presented according
    85 to latex print mode; concrete syntax is like this: @{term[show_types]
    86 "f(x) = a + x"};
    87 
    88 * isatool mkdir provides easy setup of Isabelle session directories,
    89 including proper document sources;
    90 
    91 * generated LaTeX sources are now deleted after successful run
    92 (isatool document -c); may retain a copy somewhere else via -D option
    93 of isatool usedir;
    94 
    95 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
    96 style files, achieving self-contained LaTeX sources;
    97 
    98 * old-style theories now produce (crude) LaTeX output as well;
    99 
   100 * browser info session directories are now self-contained (may be put
   101 on WWW server seperately); improved graphs of nested sessions; removed
   102 graph for 'all sessions';
   103 
   104 * several improvements in isabelle.sty; \isamarkupheader is now
   105 \section by default;
   106 
   107 
   108 *** Isar ***
   109 
   110 * Pure: local results and corresponding term bindings are now subject
   111 to Hindley-Milner polymorphism (similar to ML); this accommodates
   112 incremental type-inference nicely;
   113 
   114 * Pure: new derived language element 'obtain' supports generalized
   115 existence reasoning;
   116 
   117 * Pure: new calculational elements 'moreover' and 'ultimately' support
   118 accumulation of results, without applying any rules yet;
   119 
   120 * Pure: scalable support for case-analysis type proofs: new 'case'
   121 language element refers to local contexts symbolically, as produced by
   122 certain proof methods; internally, case names are attached to theorems
   123 as "tags";
   124 
   125 * Pure: theory command 'hide' removes declarations from
   126 class/type/const name spaces;
   127 
   128 * Pure: theory command 'defs' supports option "(overloaded)" to
   129 indicate potential overloading;
   130 
   131 * Pure: changed syntax of local blocks from {{ }} to { };
   132 
   133 * Pure: syntax of sorts made 'inner', i.e. have to write "{a, b, c}"
   134 instead of {a, b, c};
   135 
   136 * Pure now provides its own version of intro/elim/dest attributes;
   137 useful for building new logics, but beware of confusion with the
   138 Provers/classical ones;
   139 
   140 * Pure: the local context of (non-atomic) goals is provided via case
   141 name 'antecedent';
   142 
   143 * Pure: removed obsolete 'transfer' attribute (transfer of thms to the
   144 current context is now done automatically);
   145 
   146 * Pure: theory command 'method_setup' provides a simple interface for
   147 definining proof methods in ML;
   148 
   149 * Provers: splitter support (via 'split' attribute and 'simp' method
   150 modifier); 'simp' method: 'only:' modifier removes loopers as well
   151 (including splits);
   152 
   153 * HOL: new proof method 'cases' and improved version of 'induct' now
   154 support named cases; major packages (inductive, datatype, primrec,
   155 recdef) support case names and properly name parameters;
   156 
   157 * HOL: removed 'case_split' thm binding, should use 'cases' proof
   158 method anyway;
   159 
   160 * HOL/Calculation: new rules for substitution in inequalities
   161 (monotonicity conditions are extracted to be proven at end);
   162 
   163 * HOL: removed obsolete expand_if = split_if; theorems if_splits =
   164 split_if split_if_asm; datatype package provides theorems foo.splits =
   165 foo.split foo.split_asm for each datatype;
   166 
   167 * names of theorems etc. may be natural numbers as well;
   168 
   169 * Provers: intro/elim/dest attributes: changed intro/intro!/intro!!
   170 flags to intro!/intro/intro? (in most cases, one should have to change
   171 intro!! to intro? only);
   172 
   173 * 'pr' command: optional goals_limit argument; no longer prints theory
   174 contexts, but only proof states;
   175 
   176 * diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   177 additional print modes to be specified; e.g. "pr(latex)" will print
   178 proof state according to the Isabelle LaTeX style;
   179 
   180 * improved support for emulating tactic scripts, including proof
   181 methods 'tactic', 'res_inst_tac' etc., 'subgoal_tac', and 'case_tac' /
   182 'induct_tac' (for HOL datatypes);
   183 
   184 * simplified (more robust) goal selection of proof methods: 1st goal,
   185 all goals, or explicit goal specifier (tactic emulation); thus 'proof
   186 method scripts' have to be in depth-first order;
   187 
   188 * tuned 'let' syntax: replaced 'as' keyword by 'and';
   189 
   190 * removed 'help' command, which hasn't been too helpful anyway; should
   191 instead use individual commands for printing items (print_commands,
   192 print_methods etc.);
   193 
   194 * added 'nothing' --- the empty list of theorems;
   195 
   196 
   197 *** HOL ***
   198 
   199 * HOL/Algebra: new theory of rings and univariate polynomials, by
   200 Clemens Ballarin;
   201 
   202 * HOL/ex: new theory Factorization proving the Fundamental Theorem of
   203 Arithmetic, by Thomas M Rasmussen;
   204 
   205 * HOL/ex/Multiquote: multiple nested quotations and anti-quotations --
   206 basically a generalized version of de-Bruijn representation; very
   207 useful in avoiding lifting of operations;
   208 
   209 * HOL/NumberTheory: Chinese Remainder Theorem, Fermat/Euler Theorem, Wilson's
   210 Theorem, by Thomas M Rasmussen;
   211 
   212 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog;
   213 
   214 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   215 
   216 * HOL/record: fixed select-update simplification procedure to handle
   217 extended records as well; admit "r" as field name;
   218 
   219 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   220 other numeric types and also as the identity of groups, rings, etc.;
   221 
   222 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   223 Types nat and int belong to this axclass;
   224 
   225 * greatly improved simplification involving numerals of type nat, int, real:
   226    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   227    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   228   two terms #m*u and #n*u are replaced by #(m+n)*u
   229     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   230   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   231     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   232 
   233 * HOL: new version of "case_tac" subsumes both boolean case split and
   234 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   235 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   236 
   237 * HOL: simplification no longer dives into case-expressions: only the
   238 selector expression is simplified, but not the remaining arms. To
   239 enable full simplification of case-expressions for datatype t, you
   240 need to remove t.weak_case_cong from the simpset, either permanently
   241 (Delcongs[thm"t.weak_case_cong"];) or locally (delcongs [...]).
   242 
   243 * HOL/recdef: the recursion equations generated by 'recdef' for
   244 function 'f' are now called f.simps instead of f.rules; if all
   245 termination conditions are proved automatically, these simplification
   246 rules are added to the simpset, as in primrec; rules may be named
   247 individually as well, resulting in a separate list of theorems for
   248 each equation;
   249 
   250 * HOL/While is a new theory that provides a while-combinator. It
   251 permits the definition of tail-recursive functions without the
   252 provision of a termination measure. The latter is necessary once the
   253 invariant proof rule for while is applied.
   254 
   255 * HOL: new (overloaded) notation for the set of elements below/above some
   256 element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   257 
   258 * HOL: theorems impI, allI, ballI bound as "strip";
   259 
   260 * theory Sexp now in HOL/Induct examples (it used to be part of main
   261 HOL, but was unused);
   262 
   263 * fewer consts declared as global (e.g. have to refer to "Lfp.lfp"
   264 instead of "lfp" internally; affects ML packages only);
   265 
   266 * tuned AST representation of nested pairs, avoiding bogus output in
   267 case of overlap with user translations (e.g. judgements over tuples);
   268 
   269 
   270 *** ZF ***
   271 
   272 * simplification automatically cancels common terms in arithmetic expressions
   273 over nat and int;
   274 
   275 * new treatment of nat to minimize type-checking: all operators coerce their 
   276 operands to a natural number using the function natify, making the algebraic
   277 laws unconditional;
   278 
   279 * as above, for int: operators coerce their operands to an integer using the
   280 function intify;
   281 
   282 * the integer library now contains many of the usual laws for the orderings, 
   283 including $<=, and monotonicity laws for $+ and $*; 
   284 
   285 
   286 *** FOL & ZF ***
   287 
   288 * AddIffs now available, giving theorems of the form P<->Q to the
   289 simplifier and classical reasoner simultaneously;
   290 
   291 
   292 *** General ***
   293 
   294 * blast(_tac) now handles actual object-logic rules as assumptions;
   295 note that auto(_tac) uses blast(_tac) internally, too;
   296 
   297 * AST translation rules no longer require constant head on LHS;
   298 
   299 * improved name spaces: ambiguous output is qualified; support for
   300 hiding of names;
   301 
   302 * compression of ML heaps images may now be controlled via -c option
   303 of isabelle and isatool usedir (currently only observed by Poly/ML);
   304 
   305 * provide TAGS file for Isabelle sources;
   306 
   307 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
   308 order;
   309 
   310 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
   311 timing flag supersedes proof_timing and Toplevel.trace;
   312 
   313 * ML: PureThy.add_defs gets additional argument to indicate potential
   314 overloading (usually false);
   315 
   316 * ML: new combinators |>> and |>>> for incremental transformations
   317 with secondary results (e.g. certain theory extensions):
   318 
   319 
   320 
   321 New in Isabelle99 (October 1999)
   322 --------------------------------
   323 
   324 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   325 
   326 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
   327 are no longer simplified.  (This allows the simplifier to unfold recursive
   328 functional programs.)  To restore the old behaviour, declare
   329 
   330     Delcongs [if_weak_cong];
   331 
   332 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
   333 complement;
   334 
   335 * HOL: the predicate "inj" is now defined by translation to "inj_on";
   336 
   337 * HOL/datatype: mutual_induct_tac no longer exists --
   338   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
   339 
   340 * HOL/typedef: fixed type inference for representing set; type
   341 arguments now have to occur explicitly on the rhs as type constraints;
   342 
   343 * ZF: The con_defs part of an inductive definition may no longer refer
   344 to constants declared in the same theory;
   345 
   346 * HOL, ZF: the function mk_cases, generated by the inductive
   347 definition package, has lost an argument.  To simplify its result, it
   348 uses the default simpset instead of a supplied list of theorems.
   349 
   350 * HOL/List: the constructors of type list are now Nil and Cons;
   351 
   352 * Simplifier: the type of the infix ML functions
   353         setSSolver addSSolver setSolver addSolver
   354 is now  simpset * solver -> simpset  where `solver' is a new abstract type
   355 for packaging solvers. A solver is created via
   356         mk_solver: string -> (thm list -> int -> tactic) -> solver
   357 where the string argument is only a comment.
   358 
   359 
   360 *** Proof tools ***
   361 
   362 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
   363 decision procedure for linear arithmetic. Currently it is used for
   364 types `nat', `int', and `real' in HOL (see below); it can, should and
   365 will be instantiated for other types and logics as well.
   366 
   367 * The simplifier now accepts rewrite rules with flexible heads, eg
   368      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
   369   They are applied like any rule with a non-pattern lhs, i.e. by first-order
   370   matching.
   371 
   372 
   373 *** General ***
   374 
   375 * New Isabelle/Isar subsystem provides an alternative to traditional
   376 tactical theorem proving; together with the ProofGeneral/isar user
   377 interface it offers an interactive environment for developing human
   378 readable proof documents (Isar == Intelligible semi-automated
   379 reasoning); for further information see isatool doc isar-ref,
   380 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
   381 
   382 * improved presentation of theories: better HTML markup (including
   383 colors), graph views in several sizes; isatool usedir now provides a
   384 proper interface for user theories (via -P option); actual document
   385 preparation based on (PDF)LaTeX is available as well (for new-style
   386 theories only); see isatool doc system for more information;
   387 
   388 * native support for Proof General, both for classic Isabelle and
   389 Isabelle/Isar;
   390 
   391 * ML function thm_deps visualizes dependencies of theorems and lemmas,
   392 using the graph browser tool;
   393 
   394 * Isabelle manuals now also available as PDF;
   395 
   396 * theory loader rewritten from scratch (may not be fully
   397 bug-compatible); old loadpath variable has been replaced by show_path,
   398 add_path, del_path, reset_path functions; new operations such as
   399 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
   400 isatool doc ref);
   401 
   402 * improved isatool install: option -k creates KDE application icon,
   403 option -p DIR installs standalone binaries;
   404 
   405 * added ML_PLATFORM setting (useful for cross-platform installations);
   406 more robust handling of platform specific ML images for SML/NJ;
   407 
   408 * the settings environment is now statically scoped, i.e. it is never
   409 created again in sub-processes invoked from isabelle, isatool, or
   410 Isabelle;
   411 
   412 * path element specification '~~' refers to '$ISABELLE_HOME';
   413 
   414 * in locales, the "assumes" and "defines" parts may be omitted if
   415 empty;
   416 
   417 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   418 long arrows);
   419 
   420 * new print_mode "HTML";
   421 
   422 * new flag show_tags controls display of tags of theorems (which are
   423 basically just comments that may be attached by some tools);
   424 
   425 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   426 mode and goal output format:
   427 
   428 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   429 244c244
   430 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   431 ---
   432 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   433 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   434 181c181
   435 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   436 ---
   437 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   438 
   439 * function bind_thms stores lists of theorems (cf. bind_thm);
   440 
   441 * new shorthand tactics ftac, eatac, datac, fatac;
   442 
   443 * qed (and friends) now accept "" as result name; in that case the
   444 theorem is not stored, but proper checks and presentation of the
   445 result still apply;
   446 
   447 * theorem database now also indexes constants "Trueprop", "all",
   448 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   449 
   450 
   451 *** HOL ***
   452 
   453 ** HOL arithmetic **
   454 
   455 * There are now decision procedures for linear arithmetic over nat and
   456 int:
   457 
   458 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   459 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   460 are treated as atomic; subformulae not involving type `nat' or `int'
   461 are ignored; quantified subformulae are ignored unless they are
   462 positive universal or negative existential. The tactic has to be
   463 invoked by hand and can be a little bit slow. In particular, the
   464 running time is exponential in the number of occurrences of `min' and
   465 `max', and `-' on `nat'.
   466 
   467 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   468 (negated) (in)equalities among the premises and the conclusion into
   469 account (i.e. no compound formulae) and does not know about `min' and
   470 `max', and `-' on `nat'. It is fast and is used automatically by the
   471 simplifier.
   472 
   473 NB: At the moment, these decision procedures do not cope with mixed
   474 nat/int formulae where the two parts interact, such as `m < n ==>
   475 int(m) < int(n)'.
   476 
   477 * HOL/Numeral provides a generic theory of numerals (encoded
   478 efficiently as bit strings); setup for types nat/int/real is in place;
   479 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   480 int, existing theories and proof scripts may require a few additional
   481 type constraints;
   482 
   483 * integer division and remainder can now be performed on constant
   484 arguments;
   485 
   486 * many properties of integer multiplication, division and remainder
   487 are now available;
   488 
   489 * An interface to the Stanford Validity Checker (SVC) is available through the
   490 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   491 are proved automatically.  SVC must be installed separately, and its results
   492 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   493 invocation of the underlying oracle).  For SVC see
   494   http://verify.stanford.edu/SVC
   495 
   496 * IsaMakefile: the HOL-Real target now builds an actual image;
   497 
   498 
   499 ** HOL misc **
   500 
   501 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   502 (in Isabelle/Isar) -- by Gertrud Bauer;
   503 
   504 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   505 analysis for assembly languages with subtypes;
   506 
   507 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   508 -- avoids syntactic ambiguities and treats state, transition, and
   509 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   510 changed syntax and (many) tactics;
   511 
   512 * HOL/inductive: Now also handles more general introduction rules such
   513   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
   514   theorems are now maintained within the theory (maintained via the
   515   "mono" attribute);
   516 
   517 * HOL/datatype: Now also handles arbitrarily branching datatypes
   518   (using function types) such as
   519 
   520   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
   521 
   522 * HOL/record: record_simproc (part of the default simpset) takes care
   523 of selectors applied to updated records; record_split_tac is no longer
   524 part of the default claset; update_defs may now be removed from the
   525 simpset in many cases; COMPATIBILITY: old behavior achieved by
   526 
   527   claset_ref () := claset() addSWrapper record_split_wrapper;
   528   Delsimprocs [record_simproc]
   529 
   530 * HOL/typedef: fixed type inference for representing set; type
   531 arguments now have to occur explicitly on the rhs as type constraints;
   532 
   533 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
   534 names rather than an ML expression;
   535 
   536 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
   537 supplied later.  Program schemes can be defined, such as
   538     "While B C s = (if B s then While B C (C s) else s)"
   539 where the well-founded relation can be chosen after B and C have been given.
   540 
   541 * HOL/List: the constructors of type list are now Nil and Cons;
   542 INCOMPATIBILITY: while [] and infix # syntax is still there, of
   543 course, ML tools referring to List.list.op # etc. have to be adapted;
   544 
   545 * HOL_quantifiers flag superseded by "HOL" print mode, which is
   546 disabled by default; run isabelle with option -m HOL to get back to
   547 the original Gordon/HOL-style output;
   548 
   549 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
   550 ALL x<=y. P, EX x<y. P, EX x<=y. P;
   551 
   552 * HOL basic syntax simplified (more orthogonal): all variants of
   553 All/Ex now support plain / symbolic / HOL notation; plain syntax for
   554 Eps operator is provided as well: "SOME x. P[x]";
   555 
   556 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
   557 
   558 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
   559 thus available for user theories;
   560 
   561 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
   562 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
   563 time;
   564 
   565 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
   566 several times and then mp;
   567 
   568 
   569 *** LK ***
   570 
   571 * the notation <<...>> is now available as a notation for sequences of
   572 formulas;
   573 
   574 * the simplifier is now installed
   575 
   576 * the axiom system has been generalized (thanks to Soren Heilmann)
   577 
   578 * the classical reasoner now has a default rule database
   579 
   580 
   581 *** ZF ***
   582 
   583 * new primrec section allows primitive recursive functions to be given
   584 directly (as in HOL) over datatypes and the natural numbers;
   585 
   586 * new tactics induct_tac and exhaust_tac for induction (or case
   587 analysis) over datatypes and the natural numbers;
   588 
   589 * the datatype declaration of type T now defines the recursor T_rec;
   590 
   591 * simplification automatically does freeness reasoning for datatype
   592 constructors;
   593 
   594 * automatic type-inference, with AddTCs command to insert new
   595 type-checking rules;
   596 
   597 * datatype introduction rules are now added as Safe Introduction rules
   598 to the claset;
   599 
   600 * the syntax "if P then x else y" is now available in addition to
   601 if(P,x,y);
   602 
   603 
   604 *** Internal programming interfaces ***
   605 
   606 * tuned simplifier trace output; new flag debug_simp;
   607 
   608 * structures Vartab / Termtab (instances of TableFun) offer efficient
   609 tables indexed by indexname_ord / term_ord (compatible with aconv);
   610 
   611 * AxClass.axclass_tac lost the theory argument;
   612 
   613 * tuned current_goals_markers semantics: begin / end goal avoids
   614 printing empty lines;
   615 
   616 * removed prs and prs_fn hook, which was broken because it did not
   617 include \n in its semantics, forcing writeln to add one
   618 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
   619 string -> unit if you really want to output text without newline;
   620 
   621 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
   622 plain output, interface builders may have to enable 'isabelle_font'
   623 mode to get Isabelle font glyphs as before;
   624 
   625 * refined token_translation interface; INCOMPATIBILITY: output length
   626 now of type real instead of int;
   627 
   628 * theory loader actions may be traced via new ThyInfo.add_hook
   629 interface (see src/Pure/Thy/thy_info.ML); example application: keep
   630 your own database of information attached to *whole* theories -- as
   631 opposed to intra-theory data slots offered via TheoryDataFun;
   632 
   633 * proper handling of dangling sort hypotheses (at last!);
   634 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
   635 extra sort hypotheses that can be witnessed from the type signature;
   636 the force_strip_shyps flag is gone, any remaining shyps are simply
   637 left in the theorem (with a warning issued by strip_shyps_warning);
   638 
   639 
   640 
   641 New in Isabelle98-1 (October 1998)
   642 ----------------------------------
   643 
   644 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   645 
   646 * several changes of automated proof tools;
   647 
   648 * HOL: major changes to the inductive and datatype packages, including
   649 some minor incompatibilities of theory syntax;
   650 
   651 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
   652 called `inj_on';
   653 
   654 * HOL: removed duplicate thms in Arith:
   655   less_imp_add_less  should be replaced by  trans_less_add1
   656   le_imp_add_le      should be replaced by  trans_le_add1
   657 
   658 * HOL: unary minus is now overloaded (new type constraints may be
   659 required);
   660 
   661 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
   662 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
   663 now taken as an integer constant.
   664 
   665 * Pure: ML function 'theory_of' renamed to 'theory';
   666 
   667 
   668 *** Proof tools ***
   669 
   670 * Simplifier:
   671   1. Asm_full_simp_tac is now more aggressive.
   672      1. It will sometimes reorient premises if that increases their power to
   673         simplify.
   674      2. It does no longer proceed strictly from left to right but may also
   675         rotate premises to achieve further simplification.
   676      For compatibility reasons there is now Asm_lr_simp_tac which is like the
   677      old Asm_full_simp_tac in that it does not rotate premises.
   678   2. The simplifier now knows a little bit about nat-arithmetic.
   679 
   680 * Classical reasoner: wrapper mechanism for the classical reasoner now
   681 allows for selected deletion of wrappers, by introduction of names for
   682 wrapper functionals.  This implies that addbefore, addSbefore,
   683 addaltern, and addSaltern now take a pair (name, tactic) as argument,
   684 and that adding two tactics with the same name overwrites the first
   685 one (emitting a warning).
   686   type wrapper = (int -> tactic) -> (int -> tactic)
   687   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
   688   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
   689   delWrapper, delSWrapper: claset *  string            -> claset
   690   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
   691 
   692 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
   693 semantics; addbefore now affects only the unsafe part of step_tac
   694 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
   695 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
   696 by Force_tac;
   697 
   698 * Classical reasoner: setwrapper to setWrapper and compwrapper to
   699 compWrapper; added safe wrapper (and access functions for it);
   700 
   701 * HOL/split_all_tac is now much faster and fails if there is nothing
   702 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
   703 and the names of the automatically generated variables have changed.
   704 split_all_tac has moved within claset() from unsafe wrappers to safe
   705 wrappers, which means that !!-bound variables are split much more
   706 aggressively, and safe_tac and clarify_tac now split such variables.
   707 If this splitting is not appropriate, use delSWrapper "split_all_tac".
   708 Note: the same holds for record_split_tac, which does the job of
   709 split_all_tac for record fields.
   710 
   711 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
   712 permanently to the default simpset using Addsplits just like
   713 Addsimps. They can be removed via Delsplits just like
   714 Delsimps. Lower-case versions are also available.
   715 
   716 * HOL/Simplifier: The rule split_if is now part of the default
   717 simpset. This means that the simplifier will eliminate all occurrences
   718 of if-then-else in the conclusion of a goal. To prevent this, you can
   719 either remove split_if completely from the default simpset by
   720 `Delsplits [split_if]' or remove it in a specific call of the
   721 simplifier using `... delsplits [split_if]'.  You can also add/delete
   722 other case splitting rules to/from the default simpset: every datatype
   723 generates suitable rules `split_t_case' and `split_t_case_asm' (where
   724 t is the name of the datatype).
   725 
   726 * Classical reasoner / Simplifier combination: new force_tac (and
   727 derivatives Force_tac, force) combines rewriting and classical
   728 reasoning (and whatever other tools) similarly to auto_tac, but is
   729 aimed to solve the given subgoal completely.
   730 
   731 
   732 *** General ***
   733 
   734 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
   735 and `goalw': the theory is no longer needed as an explicit argument -
   736 the current theory context is used; assumptions are no longer returned
   737 at the ML-level unless one of them starts with ==> or !!; it is
   738 recommended to convert to these new commands using isatool fixgoal
   739 (backup your sources first!);
   740 
   741 * new top-level commands 'thm' and 'thms' for retrieving theorems from
   742 the current theory context, and 'theory' to lookup stored theories;
   743 
   744 * new theory section 'locale' for declaring constants, assumptions and
   745 definitions that have local scope;
   746 
   747 * new theory section 'nonterminals' for purely syntactic types;
   748 
   749 * new theory section 'setup' for generic ML setup functions
   750 (e.g. package initialization);
   751 
   752 * the distribution now includes Isabelle icons: see
   753 lib/logo/isabelle-{small,tiny}.xpm;
   754 
   755 * isatool install - install binaries with absolute references to
   756 ISABELLE_HOME/bin;
   757 
   758 * isatool logo -- create instances of the Isabelle logo (as EPS);
   759 
   760 * print mode 'emacs' reserved for Isamode;
   761 
   762 * support multiple print (ast) translations per constant name;
   763 
   764 * theorems involving oracles are now printed with a suffixed [!];
   765 
   766 
   767 *** HOL ***
   768 
   769 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
   770 
   771 * HOL/inductive package reorganized and improved: now supports mutual
   772 definitions such as
   773 
   774   inductive EVEN ODD
   775     intrs
   776       null "0 : EVEN"
   777       oddI "n : EVEN ==> Suc n : ODD"
   778       evenI "n : ODD ==> Suc n : EVEN"
   779 
   780 new theorem list "elims" contains an elimination rule for each of the
   781 recursive sets; inductive definitions now handle disjunctive premises
   782 correctly (also ZF);
   783 
   784 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   785 "mutual_induct" no longer exists - the induction rule is always
   786 contained in "induct";
   787 
   788 
   789 * HOL/datatype package re-implemented and greatly improved: now
   790 supports mutually recursive datatypes such as
   791 
   792   datatype
   793     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
   794             | SUM ('a aexp) ('a aexp)
   795             | DIFF ('a aexp) ('a aexp)
   796             | NUM 'a
   797   and
   798     'a bexp = LESS ('a aexp) ('a aexp)
   799             | AND ('a bexp) ('a bexp)
   800             | OR ('a bexp) ('a bexp)
   801 
   802 as well as indirectly recursive datatypes such as
   803 
   804   datatype
   805     ('a, 'b) term = Var 'a
   806                   | App 'b ((('a, 'b) term) list)
   807 
   808 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
   809 induction on mutually / indirectly recursive datatypes.
   810 
   811 Primrec equations are now stored in theory and can be accessed via
   812 <function_name>.simps.
   813 
   814 INCOMPATIBILITIES:
   815 
   816   - Theories using datatypes must now have theory Datatype as an
   817     ancestor.
   818   - The specific <typename>.induct_tac no longer exists - use the
   819     generic induct_tac instead.
   820   - natE has been renamed to nat.exhaust - use exhaust_tac
   821     instead of res_inst_tac ... natE. Note that the variable
   822     names in nat.exhaust differ from the names in natE, this
   823     may cause some "fragile" proofs to fail.
   824   - The theorems split_<typename>_case and split_<typename>_case_asm
   825     have been renamed to <typename>.split and <typename>.split_asm.
   826   - Since default sorts of type variables are now handled correctly,
   827     some datatype definitions may have to be annotated with explicit
   828     sort constraints.
   829   - Primrec definitions no longer require function name and type
   830     of recursive argument.
   831 
   832 Consider using isatool fixdatatype to adapt your theories and proof
   833 scripts to the new package (backup your sources first!).
   834 
   835 
   836 * HOL/record package: considerably improved implementation; now
   837 includes concrete syntax for record types, terms, updates; theorems
   838 for surjective pairing and splitting !!-bound record variables; proof
   839 support is as follows:
   840 
   841   1) standard conversions (selectors or updates applied to record
   842 constructor terms) are part of the standard simpset;
   843 
   844   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
   845 made part of standard simpset and claset via addIffs;
   846 
   847   3) a tactic for record field splitting (record_split_tac) is part of
   848 the standard claset (addSWrapper);
   849 
   850 To get a better idea about these rules you may retrieve them via
   851 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
   852 the name of your record type.
   853 
   854 The split tactic 3) conceptually simplifies by the following rule:
   855 
   856   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
   857 
   858 Thus any record variable that is bound by meta-all will automatically
   859 blow up into some record constructor term, consequently the
   860 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
   861 solve record problems automatically.
   862 
   863 
   864 * reorganized the main HOL image: HOL/Integ and String loaded by
   865 default; theory Main includes everything;
   866 
   867 * automatic simplification of integer sums and comparisons, using cancellation;
   868 
   869 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
   870 
   871 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
   872 
   873 * many new identities for unions, intersections, set difference, etc.;
   874 
   875 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
   876 called split_if, split_split, split_sum_case and split_nat_case (to go
   877 with add/delsplits);
   878 
   879 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
   880 (?x::unit) = (); this is made part of the default simpset, which COULD
   881 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
   882 'Delsimprocs [unit_eq_proc];' as last resort); also note that
   883 unit_abs_eta_conv is added in order to counter the effect of
   884 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
   885 %u.f();
   886 
   887 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
   888 makes more sense);
   889 
   890 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   891   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   892   disjointness reasoning but breaking a few old proofs.
   893 
   894 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
   895 to 'converse' from 'inverse' (for compatibility with ZF and some
   896 literature);
   897 
   898 * HOL/recdef can now declare non-recursive functions, with {} supplied as
   899 the well-founded relation;
   900 
   901 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
   902     Compl A.  The "Compl" syntax remains available as input syntax for this
   903     release ONLY.
   904 
   905 * HOL/Update: new theory of function updates:
   906     f(a:=b) == %x. if x=a then b else f x
   907 may also be iterated as in f(a:=b,c:=d,...);
   908 
   909 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
   910 
   911 * HOL/List:
   912   - new function list_update written xs[i:=v] that updates the i-th
   913     list position. May also be iterated as in xs[i:=a,j:=b,...].
   914   - new function `upt' written [i..j(] which generates the list
   915     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
   916     bound write [i..j], which is a shorthand for [i..j+1(].
   917   - new lexicographic orderings and corresponding wellfoundedness theorems.
   918 
   919 * HOL/Arith:
   920   - removed 'pred' (predecessor) function;
   921   - generalized some theorems about n-1;
   922   - many new laws about "div" and "mod";
   923   - new laws about greatest common divisors (see theory ex/Primes);
   924 
   925 * HOL/Relation: renamed the relational operator r^-1 "converse"
   926 instead of "inverse";
   927 
   928 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
   929   of the multiset ordering;
   930 
   931 * directory HOL/Real: a construction of the reals using Dedekind cuts
   932   (not included by default);
   933 
   934 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
   935 
   936 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
   937   programs, i.e. different program variables may have different types.
   938 
   939 * calling (stac rew i) now fails if "rew" has no effect on the goal
   940   [previously, this check worked only if the rewrite rule was unconditional]
   941   Now rew can involve either definitions or equalities (either == or =).
   942 
   943 
   944 *** ZF ***
   945 
   946 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
   947   only the theorems proved on ZF.ML;
   948 
   949 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   950   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   951   disjointness reasoning but breaking a few old proofs.
   952 
   953 * ZF/Update: new theory of function updates
   954     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
   955   may also be iterated as in f(a:=b,c:=d,...);
   956 
   957 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
   958 
   959 * calling (stac rew i) now fails if "rew" has no effect on the goal
   960   [previously, this check worked only if the rewrite rule was unconditional]
   961   Now rew can involve either definitions or equalities (either == or =).
   962 
   963 * case_tac provided for compatibility with HOL
   964     (like the old excluded_middle_tac, but with subgoals swapped)
   965 
   966 
   967 *** Internal programming interfaces ***
   968 
   969 * Pure: several new basic modules made available for general use, see
   970 also src/Pure/README;
   971 
   972 * improved the theory data mechanism to support encapsulation (data
   973 kind name replaced by private Object.kind, acting as authorization
   974 key); new type-safe user interface via functor TheoryDataFun; generic
   975 print_data function becomes basically useless;
   976 
   977 * removed global_names compatibility flag -- all theory declarations
   978 are qualified by default;
   979 
   980 * module Pure/Syntax now offers quote / antiquote translation
   981 functions (useful for Hoare logic etc. with implicit dependencies);
   982 see HOL/ex/Antiquote for an example use;
   983 
   984 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
   985 cterm -> thm;
   986 
   987 * new tactical CHANGED_GOAL for checking that a tactic modifies a
   988 subgoal;
   989 
   990 * Display.print_goals function moved to Locale.print_goals;
   991 
   992 * standard print function for goals supports current_goals_markers
   993 variable for marking begin of proof, end of proof, start of goal; the
   994 default is ("", "", ""); setting current_goals_markers := ("<proof>",
   995 "</proof>", "<goal>") causes SGML like tagged proof state printing,
   996 for example;
   997 
   998 
   999 
  1000 New in Isabelle98 (January 1998)
  1001 --------------------------------
  1002 
  1003 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1004 
  1005 * changed lexical syntax of terms / types: dots made part of long
  1006 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1007 
  1008 * simpset (and claset) reference variable replaced by functions
  1009 simpset / simpset_ref;
  1010 
  1011 * no longer supports theory aliases (via merge) and non-trivial
  1012 implicit merge of thms' signatures;
  1013 
  1014 * most internal names of constants changed due to qualified names;
  1015 
  1016 * changed Pure/Sequence interface (see Pure/seq.ML);
  1017 
  1018 
  1019 *** General Changes ***
  1020 
  1021 * hierachically structured name spaces (for consts, types, axms, thms
  1022 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1023 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1024 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1025 long_names for fully qualified output names; NOTE: ML programs
  1026 (special tactics, packages etc.) referring to internal names may have
  1027 to be adapted to cope with fully qualified names; in case of severe
  1028 backward campatibility problems try setting 'global_names' at compile
  1029 time to have enrything declared within a flat name space; one may also
  1030 fine tune name declarations in theories via the 'global' and 'local'
  1031 section;
  1032 
  1033 * reimplemented the implicit simpset and claset using the new anytype
  1034 data filed in signatures; references simpset:simpset ref etc. are
  1035 replaced by functions simpset:unit->simpset and
  1036 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1037 to patch your ML files accordingly;
  1038 
  1039 * HTML output now includes theory graph data for display with Java
  1040 applet or isatool browser; data generated automatically via isatool
  1041 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1042 
  1043 * defs may now be conditional; improved rewrite_goals_tac to handle
  1044 conditional equations;
  1045 
  1046 * defs now admits additional type arguments, using TYPE('a) syntax;
  1047 
  1048 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1049 creates a new theory node; implicit merge of thms' signatures is
  1050 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1051 transfer:theory->thm->thm in (rare) cases;
  1052 
  1053 * improved handling of draft signatures / theories; draft thms (and
  1054 ctyps, cterms) are automatically promoted to real ones;
  1055 
  1056 * slightly changed interfaces for oracles: admit many per theory, named
  1057 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1058 
  1059 * print_goals: optional output of const types (set show_consts and
  1060 show_types);
  1061 
  1062 * improved output of warnings (###) and errors (***);
  1063 
  1064 * subgoal_tac displays a warning if the new subgoal has type variables;
  1065 
  1066 * removed old README and Makefiles;
  1067 
  1068 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1069 
  1070 * removed obsolete init_pps and init_database;
  1071 
  1072 * deleted the obsolete tactical STATE, which was declared by
  1073     fun STATE tacfun st = tacfun st st;
  1074 
  1075 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1076 (which abbreviates $HOME);
  1077 
  1078 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1079 use isatool fixseq to adapt your ML programs (this works for fully
  1080 qualified references to the Sequence structure only!);
  1081 
  1082 * use_thy no longer requires writable current directory; it always
  1083 reloads .ML *and* .thy file, if either one is out of date;
  1084 
  1085 
  1086 *** Classical Reasoner ***
  1087 
  1088 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1089 tactics that use classical reasoning to simplify a subgoal without
  1090 splitting it into several subgoals;
  1091 
  1092 * Safe_tac: like safe_tac but uses the default claset;
  1093 
  1094 
  1095 *** Simplifier ***
  1096 
  1097 * added simplification meta rules:
  1098     (asm_)(full_)simplify: simpset -> thm -> thm;
  1099 
  1100 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1101 logics (again);
  1102 
  1103 * added prems argument to simplification procedures;
  1104 
  1105 * HOL, FOL, ZF: added infix function `addsplits':
  1106   instead of `<simpset> setloop (split_tac <thms>)'
  1107   you can simply write `<simpset> addsplits <thms>'
  1108 
  1109 
  1110 *** Syntax ***
  1111 
  1112 * TYPE('a) syntax for type reflection terms;
  1113 
  1114 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1115 
  1116 * pretty printer: changed order of mixfix annotation preference (again!);
  1117 
  1118 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1119 
  1120 
  1121 *** HOL ***
  1122 
  1123 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1124   with `addloop' of the simplifier to faciliate case splitting in premises.
  1125 
  1126 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1127 
  1128 * HOL/Auth: new protocol proofs including some for the Internet
  1129   protocol TLS;
  1130 
  1131 * HOL/Map: new theory of `maps' a la VDM;
  1132 
  1133 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1134 cancelling out common nat summands from =, <, <= (in)equalities, or
  1135 differences; simplification procedures nat_cancel_factor for
  1136 cancelling common factor from =, <, <= (in)equalities over natural
  1137 sums; nat_cancel contains both kinds of procedures, it is installed by
  1138 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1139 
  1140 * HOL/simplifier: terms of the form
  1141   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1142   are rewritten to
  1143   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1144   and those of the form
  1145   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1146   are rewritten to
  1147   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1148 
  1149 * HOL/datatype
  1150   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1151 
  1152   P(t_case f1 ... fn x) =
  1153      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1154         ...
  1155        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1156      )
  1157 
  1158   and a theorem `split_t_case_asm' of the form
  1159 
  1160   P(t_case f1 ... fn x) =
  1161     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1162         ...
  1163        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1164      )
  1165   which can be added to a simpset via `addsplits'. The existing theorems
  1166   expand_list_case and expand_option_case have been renamed to
  1167   split_list_case and split_option_case.
  1168 
  1169 * HOL/Arithmetic:
  1170   - `pred n' is automatically converted to `n-1'.
  1171     Users are strongly encouraged not to use `pred' any longer,
  1172     because it will disappear altogether at some point.
  1173   - Users are strongly encouraged to write "0 < n" rather than
  1174     "n ~= 0". Theorems and proof tools have been modified towards this
  1175     `standard'.
  1176 
  1177 * HOL/Lists:
  1178   the function "set_of_list" has been renamed "set" (and its theorems too);
  1179   the function "nth" now takes its arguments in the reverse order and
  1180   has acquired the infix notation "!" as in "xs!n".
  1181 
  1182 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1183 
  1184 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1185   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1186 
  1187 * HOL/record: extensible records with schematic structural subtyping
  1188 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1189 still lacks various theorems and concrete record syntax;
  1190 
  1191 
  1192 *** HOLCF ***
  1193 
  1194 * removed "axioms" and "generated by" sections;
  1195 
  1196 * replaced "ops" section by extended "consts" section, which is capable of
  1197   handling the continuous function space "->" directly;
  1198 
  1199 * domain package:
  1200   . proves theorems immediately and stores them in the theory,
  1201   . creates hierachical name space,
  1202   . now uses normal mixfix annotations (instead of cinfix...),
  1203   . minor changes to some names and values (for consistency),
  1204   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1205   . separator between mutual domain defs: changed "," to "and",
  1206   . improved handling of sort constraints;  now they have to
  1207     appear on the left-hand side of the equations only;
  1208 
  1209 * fixed LAM <x,y,zs>.b syntax;
  1210 
  1211 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1212 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1213 
  1214 
  1215 *** FOL and ZF ***
  1216 
  1217 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1218   with `addloop' of the simplifier to faciliate case splitting in premises.
  1219 
  1220 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1221 in HOL, they strip ALL and --> from proved theorems;
  1222 
  1223 
  1224 
  1225 New in Isabelle94-8 (May 1997)
  1226 ------------------------------
  1227 
  1228 *** General Changes ***
  1229 
  1230 * new utilities to build / run / maintain Isabelle etc. (in parts
  1231 still somewhat experimental); old Makefiles etc. still functional;
  1232 
  1233 * new 'Isabelle System Manual';
  1234 
  1235 * INSTALL text, together with ./configure and ./build scripts;
  1236 
  1237 * reimplemented type inference for greater efficiency, better error
  1238 messages and clean internal interface;
  1239 
  1240 * prlim command for dealing with lots of subgoals (an easier way of
  1241 setting goals_limit);
  1242 
  1243 
  1244 *** Syntax ***
  1245 
  1246 * supports alternative (named) syntax tables (parser and pretty
  1247 printer); internal interface is provided by add_modesyntax(_i);
  1248 
  1249 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1250 be used in conjunction with the Isabelle symbol font; uses the
  1251 "symbols" syntax table;
  1252 
  1253 * added token_translation interface (may translate name tokens in
  1254 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1255 the current print_mode); IMPORTANT: user print translation functions
  1256 are responsible for marking newly introduced bounds
  1257 (Syntax.mark_boundT);
  1258 
  1259 * token translations for modes "xterm" and "xterm_color" that display
  1260 names in bold, underline etc. or colors (which requires a color
  1261 version of xterm);
  1262 
  1263 * infixes may now be declared with names independent of their syntax;
  1264 
  1265 * added typed_print_translation (like print_translation, but may
  1266 access type of constant);
  1267 
  1268 
  1269 *** Classical Reasoner ***
  1270 
  1271 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  1272 some limitations.  Blast_tac...
  1273   + ignores addss, addbefore, addafter; this restriction is intrinsic
  1274   + ignores elimination rules that don't have the correct format
  1275         (the conclusion MUST be a formula variable)
  1276   + ignores types, which can make HOL proofs fail
  1277   + rules must not require higher-order unification, e.g. apply_type in ZF
  1278     [message "Function Var's argument not a bound variable" relates to this]
  1279   + its proof strategy is more general but can actually be slower
  1280 
  1281 * substitution with equality assumptions no longer permutes other
  1282 assumptions;
  1283 
  1284 * minor changes in semantics of addafter (now called addaltern); renamed
  1285 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  1286 (and access functions for it);
  1287 
  1288 * improved combination of classical reasoner and simplifier:
  1289   + functions for handling clasimpsets
  1290   + improvement of addss: now the simplifier is called _after_ the
  1291     safe steps.
  1292   + safe variant of addss called addSss: uses safe simplifications
  1293     _during_ the safe steps. It is more complete as it allows multiple
  1294     instantiations of unknowns (e.g. with slow_tac).
  1295 
  1296 *** Simplifier ***
  1297 
  1298 * added interface for simplification procedures (functions that
  1299 produce *proven* rewrite rules on the fly, depending on current
  1300 redex);
  1301 
  1302 * ordering on terms as parameter (used for ordered rewriting);
  1303 
  1304 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  1305 
  1306 * the solver is now split into a safe and an unsafe part.
  1307 This should be invisible for the normal user, except that the
  1308 functions setsolver and addsolver have been renamed to setSolver and
  1309 addSolver; added safe_asm_full_simp_tac;
  1310 
  1311 
  1312 *** HOL ***
  1313 
  1314 * a generic induction tactic `induct_tac' which works for all datatypes and
  1315 also for type `nat';
  1316 
  1317 * a generic case distinction tactic `exhaust_tac' which works for all
  1318 datatypes and also for type `nat';
  1319 
  1320 * each datatype comes with a function `size';
  1321 
  1322 * patterns in case expressions allow tuple patterns as arguments to
  1323 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1324 
  1325 * primrec now also works with type nat;
  1326 
  1327 * recdef: a new declaration form, allows general recursive functions to be
  1328 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1329 
  1330 * the constant for negation has been renamed from "not" to "Not" to
  1331 harmonize with FOL, ZF, LK, etc.;
  1332 
  1333 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1334 infinite lists;
  1335 
  1336 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1337 
  1338 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1339 problems in commutative rings, using axiomatic type classes for + and *;
  1340 
  1341 * more examples in HOL/MiniML and HOL/Auth;
  1342 
  1343 * more default rewrite rules for quantifiers, union/intersection;
  1344 
  1345 * a new constant `arbitrary == @x.False';
  1346 
  1347 * HOLCF/IOA replaces old HOL/IOA;
  1348 
  1349 * HOLCF changes: derived all rules and arities
  1350   + axiomatic type classes instead of classes
  1351   + typedef instead of faking type definitions
  1352   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1353   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1354   + eliminated the types void, one, tr
  1355   + use unit lift and bool lift (with translations) instead of one and tr
  1356   + eliminated blift from Lift3.thy (use Def instead of blift)
  1357   all eliminated rules are derived as theorems --> no visible changes ;
  1358 
  1359 
  1360 *** ZF ***
  1361 
  1362 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1363 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1364 as ZF_cs addSIs [equalityI];
  1365 
  1366 
  1367 
  1368 New in Isabelle94-7 (November 96)
  1369 ---------------------------------
  1370 
  1371 * allowing negative levels (as offsets) in prlev and choplev;
  1372 
  1373 * super-linear speedup for large simplifications;
  1374 
  1375 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1376 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1377 FAIL); can suppress it using the command Delsimps (ex_simps @
  1378 all_simps); De Morgan laws are also now included, by default;
  1379 
  1380 * improved printing of ==>  :  ~:
  1381 
  1382 * new object-logic "Sequents" adds linear logic, while replacing LK
  1383 and Modal (thanks to Sara Kalvala);
  1384 
  1385 * HOL/Auth: correctness proofs for authentication protocols;
  1386 
  1387 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1388 examples on HOL/Auth);
  1389 
  1390 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1391 the rewriter and classical reasoner simultaneously;
  1392 
  1393 * function uresult no longer returns theorems in "standard" format;
  1394 regain previous version by: val uresult = standard o uresult;
  1395 
  1396 
  1397 
  1398 New in Isabelle94-6
  1399 -------------------
  1400 
  1401 * oracles -- these establish an interface between Isabelle and trusted
  1402 external reasoners, which may deliver results as theorems;
  1403 
  1404 * proof objects (in particular record all uses of oracles);
  1405 
  1406 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1407 
  1408 * "constdefs" section in theory files;
  1409 
  1410 * "primrec" section (HOL) no longer requires names;
  1411 
  1412 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1413 
  1414 
  1415 
  1416 New in Isabelle94-5
  1417 -------------------
  1418 
  1419 * reduced space requirements;
  1420 
  1421 * automatic HTML generation from theories;
  1422 
  1423 * theory files no longer require "..." (quotes) around most types;
  1424 
  1425 * new examples, including two proofs of the Church-Rosser theorem;
  1426 
  1427 * non-curried (1994) version of HOL is no longer distributed;
  1428 
  1429 
  1430 
  1431 New in Isabelle94-4
  1432 -------------------
  1433 
  1434 * greatly reduced space requirements;
  1435 
  1436 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1437 
  1438 * searchable theorem database (see the section "Retrieving theorems" on
  1439 page 8 of the Reference Manual);
  1440 
  1441 * new examples, including Grabczewski's monumental case study of the
  1442 Axiom of Choice;
  1443 
  1444 * The previous version of HOL renamed to Old_HOL;
  1445 
  1446 * The new version of HOL (previously called CHOL) uses a curried syntax
  1447 for functions.  Application looks like f a b instead of f(a,b);
  1448 
  1449 * Mutually recursive inductive definitions finally work in HOL;
  1450 
  1451 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1452 translates to the operator "split";
  1453 
  1454 
  1455 
  1456 New in Isabelle94-3
  1457 -------------------
  1458 
  1459 * new infix operator, addss, allowing the classical reasoner to
  1460 perform simplification at each step of its search.  Example:
  1461         fast_tac (cs addss ss)
  1462 
  1463 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1464 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1465 look like (a,b) instead of <a,b>;
  1466 
  1467 * PLEASE NOTE: CHOL will eventually replace HOL!
  1468 
  1469 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1470 It translates to the operator "split".  A new theory of integers is available;
  1471 
  1472 * In ZF, integer numerals now denote two's-complement binary integers.
  1473 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1474 
  1475 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1476 of the Axiom of Choice;
  1477 
  1478 
  1479 
  1480 New in Isabelle94-2
  1481 -------------------
  1482 
  1483 * Significantly faster resolution;
  1484 
  1485 * the different sections in a .thy file can now be mixed and repeated
  1486 freely;
  1487 
  1488 * Database of theorems for FOL, HOL and ZF.  New
  1489 commands including qed, qed_goal and bind_thm store theorems in the database.
  1490 
  1491 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1492 a given theory (thms_of), or find out what theory a theorem was proved in
  1493 (theory_of_thm);
  1494 
  1495 * Bugs fixed in the inductive definition and datatype packages;
  1496 
  1497 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1498 and HOL_dup_cs obsolete;
  1499 
  1500 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1501 have been removed;
  1502 
  1503 * Simpler definition of function space in ZF;
  1504 
  1505 * new results about cardinal and ordinal arithmetic in ZF;
  1506 
  1507 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1508 types;
  1509 
  1510 
  1511 $Id$