NEWS
author paulson
Sun Sep 03 14:41:56 2000 +0200 (2000-09-03)
changeset 9816 2cb9752ff002
parent 9814 aef1f83cf8a6
child 9835 543d23cd1259
permissions -rw-r--r--
new reference girard89
     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    26 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;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 * Isar: renamed 'RS' attribute to 'THEN';
    58 
    59 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
    60 
    61 * Provers: strengthened force_tac by using new first_best_tac;
    62 
    63 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
    64   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
    65 use instead the strong form,
    66   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
    67 In HOL, FOL and ZF the function cla_make_elim will create such rules
    68 from destruct-rules;
    69 
    70 * Provers: safe_asm_full_simp_tac is no longer in the simplifier signature. Use
    71   val safe_asm_full_simp_tac = generic_simp_tac true (true,true,true);
    72   if required.
    73 
    74 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
    75 timing flag supersedes proof_timing and Toplevel.trace;
    76 
    77 * ML: PureThy.add_thms/add_axioms/add_defs return theorems as well;
    78 
    79 * ML: PureThy.add_defs gets additional argument to indicate potential
    80 overloading (usually false);
    81 
    82 * LaTeX: several changes of isabelle.sty;
    83 
    84 
    85 *** Document preparation ***
    86 
    87 * formal comments (text blocks etc.) in new-style theories may now
    88 contain antiquotations of thm/prop/term/typ/text to be presented
    89 according to latex print mode; concrete syntax is like this:
    90 @{term[show_types] "f(x) = a + x"};
    91 
    92 * isatool mkdir provides easy setup of Isabelle session directories,
    93 including proper document sources;
    94 
    95 * generated LaTeX sources are now deleted after successful run
    96 (isatool document -c); may retain a copy somewhere else via -D option
    97 of isatool usedir;
    98 
    99 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
   100 style files, achieving self-contained LaTeX sources;
   101 
   102 * old-style theories now produce (crude) LaTeX output as well;
   103 
   104 * browser info session directories are now self-contained (may be put
   105 on WWW server seperately); improved graphs of nested sessions; removed
   106 graph for 'all sessions';
   107 
   108 * several improvements in isabelle.sty; \isabellestyle{it} produces
   109 near math mode output; \isamarkupheader is now \section by default;
   110 
   111 
   112 *** Isar ***
   113 
   114 * Pure: local results and corresponding term bindings are now subject
   115 to Hindley-Milner polymorphism (similar to ML); this accommodates
   116 incremental type-inference nicely;
   117 
   118 * Pure: new derived language element 'obtain' supports generalized
   119 existence reasoning;
   120 
   121 * Pure: new calculational elements 'moreover' and 'ultimately' support
   122 accumulation of results, without applying any rules yet;
   123 
   124 * Pure: scalable support for case-analysis type proofs: new 'case'
   125 language element refers to local contexts symbolically, as produced by
   126 certain proof methods; internally, case names are attached to theorems
   127 as "tags";
   128 
   129 * Pure: theory command 'hide' removes declarations from
   130 class/type/const name spaces;
   131 
   132 * Pure: theory command 'defs' supports option "(overloaded)" to
   133 indicate potential overloading;
   134 
   135 * Pure: changed syntax of local blocks from {{ }} to { };
   136 
   137 * Pure: renamed 'RS' attribute to 'THEN';
   138 
   139 * Pure: syntax of sorts made 'inner', i.e. have to write "{a, b, c}"
   140 instead of {a, b, c};
   141 
   142 * Pure now provides its own version of intro/elim/dest attributes;
   143 useful for building new logics, but beware of confusion with the
   144 version in Provers/classical;
   145 
   146 * Pure: the local context of (non-atomic) goals is provided via case
   147 name 'antecedent';
   148 
   149 * Pure: removed obsolete 'transfer' attribute (transfer of thms to the
   150 current context is now done automatically);
   151 
   152 * Pure: theory command 'method_setup' provides a simple interface for
   153 definining proof methods in ML;
   154 
   155 * Provers: 'simp' method now supports 'cong' modifiers;
   156 
   157 * Provers: hypsubst support; also plain subst and symmetric attribute
   158 (the latter supercedes [RS sym]);
   159 
   160 * Provers: splitter support (via 'split' attribute and 'simp' method
   161 modifier); 'simp' method: 'only:' modifier removes loopers as well
   162 (including splits);
   163 
   164 * Provers: added 'fastsimp' and 'clarsimp' methods (combination of
   165 Simplifier and Classical reasoner);
   166 
   167 * Provers: added 'arith_split' attribute;
   168 
   169 * HOL: new proof method 'cases' and improved version of 'induct' now
   170 support named cases; major packages (inductive, datatype, primrec,
   171 recdef) support case names and properly name parameters;
   172 
   173 * HOL: removed 'case_split' thm binding, should use 'cases' proof
   174 method anyway;
   175 
   176 * HOL: removed obsolete expand_if = split_if; theorems if_splits =
   177 split_if split_if_asm; datatype package provides theorems foo.splits =
   178 foo.split foo.split_asm for each datatype;
   179 
   180 * HOL/Calculation: new rules for substitution in inequalities
   181 (monotonicity conditions are extracted to be proven at end);
   182 
   183 * HOL/inductive: rename "intrs" to "intros" (potential
   184 INCOMPATIBILITY); emulation of mk_cases feature for proof scripts:
   185 'inductive_cases' command and 'ind_cases' method; NOTE: use (cases
   186 (simplified)) method in proper proofs;
   187 
   188 * Provers: intro/elim/dest attributes: changed intro/intro!/intro!!
   189 flags to intro!/intro/intro? (in most cases, one should have to change
   190 intro!! to intro? only);
   191 
   192 * names of theorems etc. may be natural numbers as well;
   193 
   194 * 'pr' command: optional arguments for goals_limit and
   195 ProofContext.prems_limit; no longer prints theory contexts, but only
   196 proof states;
   197 
   198 * diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
   199 additional print modes to be specified; e.g. "pr(latex)" will print
   200 proof state according to the Isabelle LaTeX style;
   201 
   202 * improved support for emulating tactic scripts, including proof
   203 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
   204 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
   205 (for HOL datatypes);
   206 
   207 * simplified (more robust) goal selection of proof methods: 1st goal,
   208 all goals, or explicit goal specifier (tactic emulation); thus 'proof
   209 method scripts' have to be in depth-first order;
   210 
   211 * tuned 'let' syntax: replaced 'as' keyword by 'and';
   212 
   213 * removed 'help' command, which hasn't been too helpful anyway; should
   214 instead use individual commands for printing items (print_commands,
   215 print_methods etc.);
   216 
   217 * added 'nothing' --- the empty list of theorems;
   218 
   219 
   220 *** HOL ***
   221 
   222 * HOL/Lambda: converted into new-style theory and document;
   223 
   224 * HOL/Algebra: new theory of rings and univariate polynomials, by
   225 Clemens Ballarin;
   226 
   227 * HOL/ex: new theory Factorization proving the Fundamental Theorem of
   228 Arithmetic, by Thomas M Rasmussen;
   229 
   230 * HOL/ex/Multiquote: multiple nested quotations and anti-quotations --
   231 basically a generalized version of de-Bruijn representation; very
   232 useful in avoiding lifting of operations;
   233 
   234 * HOL/NumberTheory: Chinese Remainder Theorem, Fermat/Euler Theorem, Wilson's
   235 Theorem, by Thomas M Rasmussen;
   236 
   237 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog;
   238 
   239 * HOL/Real: "rabs" replaced by overloaded "abs" function;
   240 
   241 * HOL/record: added general record equality rule to simpset; fixed
   242 select-update simplification procedure to handle extended records as
   243 well; admit "r" as field name;
   244 
   245 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
   246 other numeric types and also as the identity of groups, rings, etc.;
   247 
   248 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
   249 Types nat and int belong to this axclass;
   250 
   251 * greatly improved simplification involving numerals of type nat, int, real:
   252    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
   253    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
   254   two terms #m*u and #n*u are replaced by #(m+n)*u
   255     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
   256   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
   257     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
   258 
   259 * HOL: new version of "case_tac" subsumes both boolean case split and
   260 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
   261 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
   262 
   263 * HOL: simplification no longer dives into case-expressions: only the
   264 selector expression is simplified, but not the remaining arms. To
   265 enable full simplification of case-expressions for datatype t, you
   266 need to remove t.weak_case_cong from the simpset, either permanently
   267 (Delcongs[thm"t.weak_case_cong"];) or locally (delcongs [...]).
   268 
   269 * HOL/recdef: the recursion equations generated by 'recdef' for
   270 function 'f' are now called f.simps instead of f.rules; if all
   271 termination conditions are proved automatically, these simplification
   272 rules are added to the simpset, as in primrec; rules may be named
   273 individually as well, resulting in a separate list of theorems for
   274 each equation;
   275 
   276 * HOL/While is a new theory that provides a while-combinator. It
   277 permits the definition of tail-recursive functions without the
   278 provision of a termination measure. The latter is necessary once the
   279 invariant proof rule for while is applied.
   280 
   281 * HOL: new (overloaded) notation for the set of elements below/above some
   282 element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
   283 
   284 * HOL: theorems impI, allI, ballI bound as "strip";
   285 
   286 * new tactic induct_thm_tac: thm -> string -> int -> tactic
   287 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
   288 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
   289 
   290 * new function rulify: thm -> thm for turning outer -->/! into ==>/?;
   291 behaves like qed_spec_mp;
   292 
   293 * theory Sexp now in HOL/Induct examples (it used to be part of main
   294 HOL, but was unused);
   295 
   296 * fewer consts declared as global (e.g. have to refer to "Lfp.lfp"
   297 instead of "lfp" internally; affects ML packages only);
   298 
   299 * tuned AST representation of nested pairs, avoiding bogus output in
   300 case of overlap with user translations (e.g. judgements over tuples);
   301 
   302 
   303 *** ZF ***
   304 
   305 * simplification automatically cancels common terms in arithmetic expressions
   306 over nat and int;
   307 
   308 * new treatment of nat to minimize type-checking: all operators coerce their 
   309 operands to a natural number using the function natify, making the algebraic
   310 laws unconditional;
   311 
   312 * as above, for int: operators coerce their operands to an integer using the
   313 function intify;
   314 
   315 * the integer library now contains many of the usual laws for the orderings, 
   316 including $<=, and monotonicity laws for $+ and $*; 
   317 
   318 * new example ZF/ex/NatSum to demonstrate integer arithmetic simplification;
   319 
   320 *** FOL & ZF ***
   321 
   322 * AddIffs now available, giving theorems of the form P<->Q to the
   323 simplifier and classical reasoner simultaneously;
   324 
   325 
   326 *** General ***
   327 
   328 * Provers: blast(_tac) now handles actual object-logic rules as
   329 assumptions; note that auto(_tac) uses blast(_tac) internally as well;
   330 
   331 * Provers: Simplifier.easy_setup provides a fast path to basic
   332 Simplifier setup for new object-logics;
   333 
   334 * Pure: AST translation rules no longer require constant head on LHS;
   335 
   336 * Pure: improved name spaces: ambiguous output is qualified; support
   337 for hiding of names;
   338 
   339 * system: compression of ML heaps images may now be controlled via -c
   340 option of isabelle and isatool usedir (currently only observed by
   341 Poly/ML);
   342 
   343 * system: provide TAGS file for Isabelle sources;
   344 
   345 * settings: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
   346 XSYMBOL_HOME; no longer need to do manual configuration in most
   347 situations;
   348 
   349 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
   350 order;
   351 
   352 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
   353 timing flag supersedes proof_timing and Toplevel.trace;
   354 
   355 * ML: PureThy.add_defs gets additional argument to indicate potential
   356 overloading (usually false);
   357 
   358 * ML: new combinators |>> and |>>> for incremental transformations
   359 with secondary results (e.g. certain theory extensions):
   360 
   361 
   362 
   363 New in Isabelle99 (October 1999)
   364 --------------------------------
   365 
   366 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   367 
   368 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
   369 are no longer simplified.  (This allows the simplifier to unfold recursive
   370 functional programs.)  To restore the old behaviour, declare
   371 
   372     Delcongs [if_weak_cong];
   373 
   374 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
   375 complement;
   376 
   377 * HOL: the predicate "inj" is now defined by translation to "inj_on";
   378 
   379 * HOL/datatype: mutual_induct_tac no longer exists --
   380   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
   381 
   382 * HOL/typedef: fixed type inference for representing set; type
   383 arguments now have to occur explicitly on the rhs as type constraints;
   384 
   385 * ZF: The con_defs part of an inductive definition may no longer refer
   386 to constants declared in the same theory;
   387 
   388 * HOL, ZF: the function mk_cases, generated by the inductive
   389 definition package, has lost an argument.  To simplify its result, it
   390 uses the default simpset instead of a supplied list of theorems.
   391 
   392 * HOL/List: the constructors of type list are now Nil and Cons;
   393 
   394 * Simplifier: the type of the infix ML functions
   395         setSSolver addSSolver setSolver addSolver
   396 is now  simpset * solver -> simpset  where `solver' is a new abstract type
   397 for packaging solvers. A solver is created via
   398         mk_solver: string -> (thm list -> int -> tactic) -> solver
   399 where the string argument is only a comment.
   400 
   401 
   402 *** Proof tools ***
   403 
   404 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
   405 decision procedure for linear arithmetic. Currently it is used for
   406 types `nat', `int', and `real' in HOL (see below); it can, should and
   407 will be instantiated for other types and logics as well.
   408 
   409 * The simplifier now accepts rewrite rules with flexible heads, eg
   410      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
   411   They are applied like any rule with a non-pattern lhs, i.e. by first-order
   412   matching.
   413 
   414 
   415 *** General ***
   416 
   417 * New Isabelle/Isar subsystem provides an alternative to traditional
   418 tactical theorem proving; together with the ProofGeneral/isar user
   419 interface it offers an interactive environment for developing human
   420 readable proof documents (Isar == Intelligible semi-automated
   421 reasoning); for further information see isatool doc isar-ref,
   422 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
   423 
   424 * improved and simplified presentation of theories: better HTML markup
   425 (including colors), graph views in several sizes; isatool usedir now
   426 provides a proper interface for user theories (via -P option); actual
   427 document preparation based on (PDF)LaTeX is available as well (for
   428 new-style theories only); see isatool doc system for more information;
   429 
   430 * native support for Proof General, both for classic Isabelle and
   431 Isabelle/Isar;
   432 
   433 * ML function thm_deps visualizes dependencies of theorems and lemmas,
   434 using the graph browser tool;
   435 
   436 * Isabelle manuals now also available as PDF;
   437 
   438 * theory loader rewritten from scratch (may not be fully
   439 bug-compatible); old loadpath variable has been replaced by show_path,
   440 add_path, del_path, reset_path functions; new operations such as
   441 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
   442 isatool doc ref);
   443 
   444 * improved isatool install: option -k creates KDE application icon,
   445 option -p DIR installs standalone binaries;
   446 
   447 * added ML_PLATFORM setting (useful for cross-platform installations);
   448 more robust handling of platform specific ML images for SML/NJ;
   449 
   450 * the settings environment is now statically scoped, i.e. it is never
   451 created again in sub-processes invoked from isabelle, isatool, or
   452 Isabelle;
   453 
   454 * path element specification '~~' refers to '$ISABELLE_HOME';
   455 
   456 * in locales, the "assumes" and "defines" parts may be omitted if
   457 empty;
   458 
   459 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   460 long arrows);
   461 
   462 * new print_mode "HTML";
   463 
   464 * new flag show_tags controls display of tags of theorems (which are
   465 basically just comments that may be attached by some tools);
   466 
   467 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   468 mode and goal output format:
   469 
   470 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   471 244c244
   472 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   473 ---
   474 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   475 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   476 181c181
   477 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   478 ---
   479 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   480 
   481 * function bind_thms stores lists of theorems (cf. bind_thm);
   482 
   483 * new shorthand tactics ftac, eatac, datac, fatac;
   484 
   485 * qed (and friends) now accept "" as result name; in that case the
   486 theorem is not stored, but proper checks and presentation of the
   487 result still apply;
   488 
   489 * theorem database now also indexes constants "Trueprop", "all",
   490 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   491 
   492 
   493 *** HOL ***
   494 
   495 ** HOL arithmetic **
   496 
   497 * There are now decision procedures for linear arithmetic over nat and
   498 int:
   499 
   500 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   501 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   502 are treated as atomic; subformulae not involving type `nat' or `int'
   503 are ignored; quantified subformulae are ignored unless they are
   504 positive universal or negative existential. The tactic has to be
   505 invoked by hand and can be a little bit slow. In particular, the
   506 running time is exponential in the number of occurrences of `min' and
   507 `max', and `-' on `nat'.
   508 
   509 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   510 (negated) (in)equalities among the premises and the conclusion into
   511 account (i.e. no compound formulae) and does not know about `min' and
   512 `max', and `-' on `nat'. It is fast and is used automatically by the
   513 simplifier.
   514 
   515 NB: At the moment, these decision procedures do not cope with mixed
   516 nat/int formulae where the two parts interact, such as `m < n ==>
   517 int(m) < int(n)'.
   518 
   519 * HOL/Numeral provides a generic theory of numerals (encoded
   520 efficiently as bit strings); setup for types nat/int/real is in place;
   521 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   522 int, existing theories and proof scripts may require a few additional
   523 type constraints;
   524 
   525 * integer division and remainder can now be performed on constant
   526 arguments;
   527 
   528 * many properties of integer multiplication, division and remainder
   529 are now available;
   530 
   531 * An interface to the Stanford Validity Checker (SVC) is available through the
   532 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   533 are proved automatically.  SVC must be installed separately, and its results
   534 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   535 invocation of the underlying oracle).  For SVC see
   536   http://verify.stanford.edu/SVC
   537 
   538 * IsaMakefile: the HOL-Real target now builds an actual image;
   539 
   540 
   541 ** HOL misc **
   542 
   543 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   544 (in Isabelle/Isar) -- by Gertrud Bauer;
   545 
   546 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   547 analysis for assembly languages with subtypes;
   548 
   549 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   550 -- avoids syntactic ambiguities and treats state, transition, and
   551 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   552 changed syntax and (many) tactics;
   553 
   554 * HOL/inductive: Now also handles more general introduction rules such
   555   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
   556   theorems are now maintained within the theory (maintained via the
   557   "mono" attribute);
   558 
   559 * HOL/datatype: Now also handles arbitrarily branching datatypes
   560   (using function types) such as
   561 
   562   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
   563 
   564 * HOL/record: record_simproc (part of the default simpset) takes care
   565 of selectors applied to updated records; record_split_tac is no longer
   566 part of the default claset; update_defs may now be removed from the
   567 simpset in many cases; COMPATIBILITY: old behavior achieved by
   568 
   569   claset_ref () := claset() addSWrapper record_split_wrapper;
   570   Delsimprocs [record_simproc]
   571 
   572 * HOL/typedef: fixed type inference for representing set; type
   573 arguments now have to occur explicitly on the rhs as type constraints;
   574 
   575 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
   576 names rather than an ML expression;
   577 
   578 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
   579 supplied later.  Program schemes can be defined, such as
   580     "While B C s = (if B s then While B C (C s) else s)"
   581 where the well-founded relation can be chosen after B and C have been given.
   582 
   583 * HOL/List: the constructors of type list are now Nil and Cons;
   584 INCOMPATIBILITY: while [] and infix # syntax is still there, of
   585 course, ML tools referring to List.list.op # etc. have to be adapted;
   586 
   587 * HOL_quantifiers flag superseded by "HOL" print mode, which is
   588 disabled by default; run isabelle with option -m HOL to get back to
   589 the original Gordon/HOL-style output;
   590 
   591 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
   592 ALL x<=y. P, EX x<y. P, EX x<=y. P;
   593 
   594 * HOL basic syntax simplified (more orthogonal): all variants of
   595 All/Ex now support plain / symbolic / HOL notation; plain syntax for
   596 Eps operator is provided as well: "SOME x. P[x]";
   597 
   598 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
   599 
   600 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
   601 thus available for user theories;
   602 
   603 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
   604 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
   605 time;
   606 
   607 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
   608 several times and then mp;
   609 
   610 
   611 *** LK ***
   612 
   613 * the notation <<...>> is now available as a notation for sequences of
   614 formulas;
   615 
   616 * the simplifier is now installed
   617 
   618 * the axiom system has been generalized (thanks to Soren Heilmann)
   619 
   620 * the classical reasoner now has a default rule database
   621 
   622 
   623 *** ZF ***
   624 
   625 * new primrec section allows primitive recursive functions to be given
   626 directly (as in HOL) over datatypes and the natural numbers;
   627 
   628 * new tactics induct_tac and exhaust_tac for induction (or case
   629 analysis) over datatypes and the natural numbers;
   630 
   631 * the datatype declaration of type T now defines the recursor T_rec;
   632 
   633 * simplification automatically does freeness reasoning for datatype
   634 constructors;
   635 
   636 * automatic type-inference, with AddTCs command to insert new
   637 type-checking rules;
   638 
   639 * datatype introduction rules are now added as Safe Introduction rules
   640 to the claset;
   641 
   642 * the syntax "if P then x else y" is now available in addition to
   643 if(P,x,y);
   644 
   645 
   646 *** Internal programming interfaces ***
   647 
   648 * tuned simplifier trace output; new flag debug_simp;
   649 
   650 * structures Vartab / Termtab (instances of TableFun) offer efficient
   651 tables indexed by indexname_ord / term_ord (compatible with aconv);
   652 
   653 * AxClass.axclass_tac lost the theory argument;
   654 
   655 * tuned current_goals_markers semantics: begin / end goal avoids
   656 printing empty lines;
   657 
   658 * removed prs and prs_fn hook, which was broken because it did not
   659 include \n in its semantics, forcing writeln to add one
   660 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
   661 string -> unit if you really want to output text without newline;
   662 
   663 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
   664 plain output, interface builders may have to enable 'isabelle_font'
   665 mode to get Isabelle font glyphs as before;
   666 
   667 * refined token_translation interface; INCOMPATIBILITY: output length
   668 now of type real instead of int;
   669 
   670 * theory loader actions may be traced via new ThyInfo.add_hook
   671 interface (see src/Pure/Thy/thy_info.ML); example application: keep
   672 your own database of information attached to *whole* theories -- as
   673 opposed to intra-theory data slots offered via TheoryDataFun;
   674 
   675 * proper handling of dangling sort hypotheses (at last!);
   676 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
   677 extra sort hypotheses that can be witnessed from the type signature;
   678 the force_strip_shyps flag is gone, any remaining shyps are simply
   679 left in the theorem (with a warning issued by strip_shyps_warning);
   680 
   681 
   682 
   683 New in Isabelle98-1 (October 1998)
   684 ----------------------------------
   685 
   686 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   687 
   688 * several changes of automated proof tools;
   689 
   690 * HOL: major changes to the inductive and datatype packages, including
   691 some minor incompatibilities of theory syntax;
   692 
   693 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
   694 called `inj_on';
   695 
   696 * HOL: removed duplicate thms in Arith:
   697   less_imp_add_less  should be replaced by  trans_less_add1
   698   le_imp_add_le      should be replaced by  trans_le_add1
   699 
   700 * HOL: unary minus is now overloaded (new type constraints may be
   701 required);
   702 
   703 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
   704 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
   705 now taken as an integer constant.
   706 
   707 * Pure: ML function 'theory_of' renamed to 'theory';
   708 
   709 
   710 *** Proof tools ***
   711 
   712 * Simplifier:
   713   1. Asm_full_simp_tac is now more aggressive.
   714      1. It will sometimes reorient premises if that increases their power to
   715         simplify.
   716      2. It does no longer proceed strictly from left to right but may also
   717         rotate premises to achieve further simplification.
   718      For compatibility reasons there is now Asm_lr_simp_tac which is like the
   719      old Asm_full_simp_tac in that it does not rotate premises.
   720   2. The simplifier now knows a little bit about nat-arithmetic.
   721 
   722 * Classical reasoner: wrapper mechanism for the classical reasoner now
   723 allows for selected deletion of wrappers, by introduction of names for
   724 wrapper functionals.  This implies that addbefore, addSbefore,
   725 addaltern, and addSaltern now take a pair (name, tactic) as argument,
   726 and that adding two tactics with the same name overwrites the first
   727 one (emitting a warning).
   728   type wrapper = (int -> tactic) -> (int -> tactic)
   729   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
   730   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
   731   delWrapper, delSWrapper: claset *  string            -> claset
   732   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
   733 
   734 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
   735 semantics; addbefore now affects only the unsafe part of step_tac
   736 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
   737 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
   738 by Force_tac;
   739 
   740 * Classical reasoner: setwrapper to setWrapper and compwrapper to
   741 compWrapper; added safe wrapper (and access functions for it);
   742 
   743 * HOL/split_all_tac is now much faster and fails if there is nothing
   744 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
   745 and the names of the automatically generated variables have changed.
   746 split_all_tac has moved within claset() from unsafe wrappers to safe
   747 wrappers, which means that !!-bound variables are split much more
   748 aggressively, and safe_tac and clarify_tac now split such variables.
   749 If this splitting is not appropriate, use delSWrapper "split_all_tac".
   750 Note: the same holds for record_split_tac, which does the job of
   751 split_all_tac for record fields.
   752 
   753 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
   754 permanently to the default simpset using Addsplits just like
   755 Addsimps. They can be removed via Delsplits just like
   756 Delsimps. Lower-case versions are also available.
   757 
   758 * HOL/Simplifier: The rule split_if is now part of the default
   759 simpset. This means that the simplifier will eliminate all occurrences
   760 of if-then-else in the conclusion of a goal. To prevent this, you can
   761 either remove split_if completely from the default simpset by
   762 `Delsplits [split_if]' or remove it in a specific call of the
   763 simplifier using `... delsplits [split_if]'.  You can also add/delete
   764 other case splitting rules to/from the default simpset: every datatype
   765 generates suitable rules `split_t_case' and `split_t_case_asm' (where
   766 t is the name of the datatype).
   767 
   768 * Classical reasoner / Simplifier combination: new force_tac (and
   769 derivatives Force_tac, force) combines rewriting and classical
   770 reasoning (and whatever other tools) similarly to auto_tac, but is
   771 aimed to solve the given subgoal completely.
   772 
   773 
   774 *** General ***
   775 
   776 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
   777 and `goalw': the theory is no longer needed as an explicit argument -
   778 the current theory context is used; assumptions are no longer returned
   779 at the ML-level unless one of them starts with ==> or !!; it is
   780 recommended to convert to these new commands using isatool fixgoal
   781 (backup your sources first!);
   782 
   783 * new top-level commands 'thm' and 'thms' for retrieving theorems from
   784 the current theory context, and 'theory' to lookup stored theories;
   785 
   786 * new theory section 'locale' for declaring constants, assumptions and
   787 definitions that have local scope;
   788 
   789 * new theory section 'nonterminals' for purely syntactic types;
   790 
   791 * new theory section 'setup' for generic ML setup functions
   792 (e.g. package initialization);
   793 
   794 * the distribution now includes Isabelle icons: see
   795 lib/logo/isabelle-{small,tiny}.xpm;
   796 
   797 * isatool install - install binaries with absolute references to
   798 ISABELLE_HOME/bin;
   799 
   800 * isatool logo -- create instances of the Isabelle logo (as EPS);
   801 
   802 * print mode 'emacs' reserved for Isamode;
   803 
   804 * support multiple print (ast) translations per constant name;
   805 
   806 * theorems involving oracles are now printed with a suffixed [!];
   807 
   808 
   809 *** HOL ***
   810 
   811 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
   812 
   813 * HOL/inductive package reorganized and improved: now supports mutual
   814 definitions such as
   815 
   816   inductive EVEN ODD
   817     intrs
   818       null "0 : EVEN"
   819       oddI "n : EVEN ==> Suc n : ODD"
   820       evenI "n : ODD ==> Suc n : EVEN"
   821 
   822 new theorem list "elims" contains an elimination rule for each of the
   823 recursive sets; inductive definitions now handle disjunctive premises
   824 correctly (also ZF);
   825 
   826 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   827 "mutual_induct" no longer exists - the induction rule is always
   828 contained in "induct";
   829 
   830 
   831 * HOL/datatype package re-implemented and greatly improved: now
   832 supports mutually recursive datatypes such as
   833 
   834   datatype
   835     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
   836             | SUM ('a aexp) ('a aexp)
   837             | DIFF ('a aexp) ('a aexp)
   838             | NUM 'a
   839   and
   840     'a bexp = LESS ('a aexp) ('a aexp)
   841             | AND ('a bexp) ('a bexp)
   842             | OR ('a bexp) ('a bexp)
   843 
   844 as well as indirectly recursive datatypes such as
   845 
   846   datatype
   847     ('a, 'b) term = Var 'a
   848                   | App 'b ((('a, 'b) term) list)
   849 
   850 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
   851 induction on mutually / indirectly recursive datatypes.
   852 
   853 Primrec equations are now stored in theory and can be accessed via
   854 <function_name>.simps.
   855 
   856 INCOMPATIBILITIES:
   857 
   858   - Theories using datatypes must now have theory Datatype as an
   859     ancestor.
   860   - The specific <typename>.induct_tac no longer exists - use the
   861     generic induct_tac instead.
   862   - natE has been renamed to nat.exhaust - use exhaust_tac
   863     instead of res_inst_tac ... natE. Note that the variable
   864     names in nat.exhaust differ from the names in natE, this
   865     may cause some "fragile" proofs to fail.
   866   - The theorems split_<typename>_case and split_<typename>_case_asm
   867     have been renamed to <typename>.split and <typename>.split_asm.
   868   - Since default sorts of type variables are now handled correctly,
   869     some datatype definitions may have to be annotated with explicit
   870     sort constraints.
   871   - Primrec definitions no longer require function name and type
   872     of recursive argument.
   873 
   874 Consider using isatool fixdatatype to adapt your theories and proof
   875 scripts to the new package (backup your sources first!).
   876 
   877 
   878 * HOL/record package: considerably improved implementation; now
   879 includes concrete syntax for record types, terms, updates; theorems
   880 for surjective pairing and splitting !!-bound record variables; proof
   881 support is as follows:
   882 
   883   1) standard conversions (selectors or updates applied to record
   884 constructor terms) are part of the standard simpset;
   885 
   886   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
   887 made part of standard simpset and claset via addIffs;
   888 
   889   3) a tactic for record field splitting (record_split_tac) is part of
   890 the standard claset (addSWrapper);
   891 
   892 To get a better idea about these rules you may retrieve them via
   893 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
   894 the name of your record type.
   895 
   896 The split tactic 3) conceptually simplifies by the following rule:
   897 
   898   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
   899 
   900 Thus any record variable that is bound by meta-all will automatically
   901 blow up into some record constructor term, consequently the
   902 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
   903 solve record problems automatically.
   904 
   905 
   906 * reorganized the main HOL image: HOL/Integ and String loaded by
   907 default; theory Main includes everything;
   908 
   909 * automatic simplification of integer sums and comparisons, using cancellation;
   910 
   911 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
   912 
   913 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
   914 
   915 * many new identities for unions, intersections, set difference, etc.;
   916 
   917 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
   918 called split_if, split_split, split_sum_case and split_nat_case (to go
   919 with add/delsplits);
   920 
   921 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
   922 (?x::unit) = (); this is made part of the default simpset, which COULD
   923 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
   924 'Delsimprocs [unit_eq_proc];' as last resort); also note that
   925 unit_abs_eta_conv is added in order to counter the effect of
   926 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
   927 %u.f();
   928 
   929 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
   930 makes more sense);
   931 
   932 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   933   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   934   disjointness reasoning but breaking a few old proofs.
   935 
   936 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
   937 to 'converse' from 'inverse' (for compatibility with ZF and some
   938 literature);
   939 
   940 * HOL/recdef can now declare non-recursive functions, with {} supplied as
   941 the well-founded relation;
   942 
   943 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
   944     Compl A.  The "Compl" syntax remains available as input syntax for this
   945     release ONLY.
   946 
   947 * HOL/Update: new theory of function updates:
   948     f(a:=b) == %x. if x=a then b else f x
   949 may also be iterated as in f(a:=b,c:=d,...);
   950 
   951 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
   952 
   953 * HOL/List:
   954   - new function list_update written xs[i:=v] that updates the i-th
   955     list position. May also be iterated as in xs[i:=a,j:=b,...].
   956   - new function `upt' written [i..j(] which generates the list
   957     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
   958     bound write [i..j], which is a shorthand for [i..j+1(].
   959   - new lexicographic orderings and corresponding wellfoundedness theorems.
   960 
   961 * HOL/Arith:
   962   - removed 'pred' (predecessor) function;
   963   - generalized some theorems about n-1;
   964   - many new laws about "div" and "mod";
   965   - new laws about greatest common divisors (see theory ex/Primes);
   966 
   967 * HOL/Relation: renamed the relational operator r^-1 "converse"
   968 instead of "inverse";
   969 
   970 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
   971   of the multiset ordering;
   972 
   973 * directory HOL/Real: a construction of the reals using Dedekind cuts
   974   (not included by default);
   975 
   976 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
   977 
   978 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
   979   programs, i.e. different program variables may have different types.
   980 
   981 * calling (stac rew i) now fails if "rew" has no effect on the goal
   982   [previously, this check worked only if the rewrite rule was unconditional]
   983   Now rew can involve either definitions or equalities (either == or =).
   984 
   985 
   986 *** ZF ***
   987 
   988 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
   989   only the theorems proved on ZF.ML;
   990 
   991 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   992   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   993   disjointness reasoning but breaking a few old proofs.
   994 
   995 * ZF/Update: new theory of function updates
   996     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
   997   may also be iterated as in f(a:=b,c:=d,...);
   998 
   999 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  1000 
  1001 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1002   [previously, this check worked only if the rewrite rule was unconditional]
  1003   Now rew can involve either definitions or equalities (either == or =).
  1004 
  1005 * case_tac provided for compatibility with HOL
  1006     (like the old excluded_middle_tac, but with subgoals swapped)
  1007 
  1008 
  1009 *** Internal programming interfaces ***
  1010 
  1011 * Pure: several new basic modules made available for general use, see
  1012 also src/Pure/README;
  1013 
  1014 * improved the theory data mechanism to support encapsulation (data
  1015 kind name replaced by private Object.kind, acting as authorization
  1016 key); new type-safe user interface via functor TheoryDataFun; generic
  1017 print_data function becomes basically useless;
  1018 
  1019 * removed global_names compatibility flag -- all theory declarations
  1020 are qualified by default;
  1021 
  1022 * module Pure/Syntax now offers quote / antiquote translation
  1023 functions (useful for Hoare logic etc. with implicit dependencies);
  1024 see HOL/ex/Antiquote for an example use;
  1025 
  1026 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  1027 cterm -> thm;
  1028 
  1029 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  1030 subgoal;
  1031 
  1032 * Display.print_goals function moved to Locale.print_goals;
  1033 
  1034 * standard print function for goals supports current_goals_markers
  1035 variable for marking begin of proof, end of proof, start of goal; the
  1036 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  1037 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  1038 for example;
  1039 
  1040 
  1041 
  1042 New in Isabelle98 (January 1998)
  1043 --------------------------------
  1044 
  1045 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1046 
  1047 * changed lexical syntax of terms / types: dots made part of long
  1048 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  1049 
  1050 * simpset (and claset) reference variable replaced by functions
  1051 simpset / simpset_ref;
  1052 
  1053 * no longer supports theory aliases (via merge) and non-trivial
  1054 implicit merge of thms' signatures;
  1055 
  1056 * most internal names of constants changed due to qualified names;
  1057 
  1058 * changed Pure/Sequence interface (see Pure/seq.ML);
  1059 
  1060 
  1061 *** General Changes ***
  1062 
  1063 * hierachically structured name spaces (for consts, types, axms, thms
  1064 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  1065 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  1066 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  1067 long_names for fully qualified output names; NOTE: ML programs
  1068 (special tactics, packages etc.) referring to internal names may have
  1069 to be adapted to cope with fully qualified names; in case of severe
  1070 backward campatibility problems try setting 'global_names' at compile
  1071 time to have enrything declared within a flat name space; one may also
  1072 fine tune name declarations in theories via the 'global' and 'local'
  1073 section;
  1074 
  1075 * reimplemented the implicit simpset and claset using the new anytype
  1076 data filed in signatures; references simpset:simpset ref etc. are
  1077 replaced by functions simpset:unit->simpset and
  1078 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  1079 to patch your ML files accordingly;
  1080 
  1081 * HTML output now includes theory graph data for display with Java
  1082 applet or isatool browser; data generated automatically via isatool
  1083 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  1084 
  1085 * defs may now be conditional; improved rewrite_goals_tac to handle
  1086 conditional equations;
  1087 
  1088 * defs now admits additional type arguments, using TYPE('a) syntax;
  1089 
  1090 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  1091 creates a new theory node; implicit merge of thms' signatures is
  1092 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  1093 transfer:theory->thm->thm in (rare) cases;
  1094 
  1095 * improved handling of draft signatures / theories; draft thms (and
  1096 ctyps, cterms) are automatically promoted to real ones;
  1097 
  1098 * slightly changed interfaces for oracles: admit many per theory, named
  1099 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  1100 
  1101 * print_goals: optional output of const types (set show_consts and
  1102 show_types);
  1103 
  1104 * improved output of warnings (###) and errors (***);
  1105 
  1106 * subgoal_tac displays a warning if the new subgoal has type variables;
  1107 
  1108 * removed old README and Makefiles;
  1109 
  1110 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  1111 
  1112 * removed obsolete init_pps and init_database;
  1113 
  1114 * deleted the obsolete tactical STATE, which was declared by
  1115     fun STATE tacfun st = tacfun st st;
  1116 
  1117 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  1118 (which abbreviates $HOME);
  1119 
  1120 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  1121 use isatool fixseq to adapt your ML programs (this works for fully
  1122 qualified references to the Sequence structure only!);
  1123 
  1124 * use_thy no longer requires writable current directory; it always
  1125 reloads .ML *and* .thy file, if either one is out of date;
  1126 
  1127 
  1128 *** Classical Reasoner ***
  1129 
  1130 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  1131 tactics that use classical reasoning to simplify a subgoal without
  1132 splitting it into several subgoals;
  1133 
  1134 * Safe_tac: like safe_tac but uses the default claset;
  1135 
  1136 
  1137 *** Simplifier ***
  1138 
  1139 * added simplification meta rules:
  1140     (asm_)(full_)simplify: simpset -> thm -> thm;
  1141 
  1142 * simplifier.ML no longer part of Pure -- has to be loaded by object
  1143 logics (again);
  1144 
  1145 * added prems argument to simplification procedures;
  1146 
  1147 * HOL, FOL, ZF: added infix function `addsplits':
  1148   instead of `<simpset> setloop (split_tac <thms>)'
  1149   you can simply write `<simpset> addsplits <thms>'
  1150 
  1151 
  1152 *** Syntax ***
  1153 
  1154 * TYPE('a) syntax for type reflection terms;
  1155 
  1156 * no longer handles consts with name "" -- declare as 'syntax' instead;
  1157 
  1158 * pretty printer: changed order of mixfix annotation preference (again!);
  1159 
  1160 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  1161 
  1162 
  1163 *** HOL ***
  1164 
  1165 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1166   with `addloop' of the simplifier to faciliate case splitting in premises.
  1167 
  1168 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  1169 
  1170 * HOL/Auth: new protocol proofs including some for the Internet
  1171   protocol TLS;
  1172 
  1173 * HOL/Map: new theory of `maps' a la VDM;
  1174 
  1175 * HOL/simplifier: simplification procedures nat_cancel_sums for
  1176 cancelling out common nat summands from =, <, <= (in)equalities, or
  1177 differences; simplification procedures nat_cancel_factor for
  1178 cancelling common factor from =, <, <= (in)equalities over natural
  1179 sums; nat_cancel contains both kinds of procedures, it is installed by
  1180 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  1181 
  1182 * HOL/simplifier: terms of the form
  1183   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  1184   are rewritten to
  1185   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  1186   and those of the form
  1187   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  1188   are rewritten to
  1189   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  1190 
  1191 * HOL/datatype
  1192   Each datatype `t' now comes with a theorem `split_t_case' of the form
  1193 
  1194   P(t_case f1 ... fn x) =
  1195      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  1196         ...
  1197        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  1198      )
  1199 
  1200   and a theorem `split_t_case_asm' of the form
  1201 
  1202   P(t_case f1 ... fn x) =
  1203     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  1204         ...
  1205        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  1206      )
  1207   which can be added to a simpset via `addsplits'. The existing theorems
  1208   expand_list_case and expand_option_case have been renamed to
  1209   split_list_case and split_option_case.
  1210 
  1211 * HOL/Arithmetic:
  1212   - `pred n' is automatically converted to `n-1'.
  1213     Users are strongly encouraged not to use `pred' any longer,
  1214     because it will disappear altogether at some point.
  1215   - Users are strongly encouraged to write "0 < n" rather than
  1216     "n ~= 0". Theorems and proof tools have been modified towards this
  1217     `standard'.
  1218 
  1219 * HOL/Lists:
  1220   the function "set_of_list" has been renamed "set" (and its theorems too);
  1221   the function "nth" now takes its arguments in the reverse order and
  1222   has acquired the infix notation "!" as in "xs!n".
  1223 
  1224 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  1225 
  1226 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  1227   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  1228 
  1229 * HOL/record: extensible records with schematic structural subtyping
  1230 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  1231 still lacks various theorems and concrete record syntax;
  1232 
  1233 
  1234 *** HOLCF ***
  1235 
  1236 * removed "axioms" and "generated by" sections;
  1237 
  1238 * replaced "ops" section by extended "consts" section, which is capable of
  1239   handling the continuous function space "->" directly;
  1240 
  1241 * domain package:
  1242   . proves theorems immediately and stores them in the theory,
  1243   . creates hierachical name space,
  1244   . now uses normal mixfix annotations (instead of cinfix...),
  1245   . minor changes to some names and values (for consistency),
  1246   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  1247   . separator between mutual domain defs: changed "," to "and",
  1248   . improved handling of sort constraints;  now they have to
  1249     appear on the left-hand side of the equations only;
  1250 
  1251 * fixed LAM <x,y,zs>.b syntax;
  1252 
  1253 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  1254 adm (%x. P (t x)), where P is chainfinite and t continuous;
  1255 
  1256 
  1257 *** FOL and ZF ***
  1258 
  1259 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  1260   with `addloop' of the simplifier to faciliate case splitting in premises.
  1261 
  1262 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  1263 in HOL, they strip ALL and --> from proved theorems;
  1264 
  1265 
  1266 
  1267 New in Isabelle94-8 (May 1997)
  1268 ------------------------------
  1269 
  1270 *** General Changes ***
  1271 
  1272 * new utilities to build / run / maintain Isabelle etc. (in parts
  1273 still somewhat experimental); old Makefiles etc. still functional;
  1274 
  1275 * new 'Isabelle System Manual';
  1276 
  1277 * INSTALL text, together with ./configure and ./build scripts;
  1278 
  1279 * reimplemented type inference for greater efficiency, better error
  1280 messages and clean internal interface;
  1281 
  1282 * prlim command for dealing with lots of subgoals (an easier way of
  1283 setting goals_limit);
  1284 
  1285 
  1286 *** Syntax ***
  1287 
  1288 * supports alternative (named) syntax tables (parser and pretty
  1289 printer); internal interface is provided by add_modesyntax(_i);
  1290 
  1291 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  1292 be used in conjunction with the Isabelle symbol font; uses the
  1293 "symbols" syntax table;
  1294 
  1295 * added token_translation interface (may translate name tokens in
  1296 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  1297 the current print_mode); IMPORTANT: user print translation functions
  1298 are responsible for marking newly introduced bounds
  1299 (Syntax.mark_boundT);
  1300 
  1301 * token translations for modes "xterm" and "xterm_color" that display
  1302 names in bold, underline etc. or colors (which requires a color
  1303 version of xterm);
  1304 
  1305 * infixes may now be declared with names independent of their syntax;
  1306 
  1307 * added typed_print_translation (like print_translation, but may
  1308 access type of constant);
  1309 
  1310 
  1311 *** Classical Reasoner ***
  1312 
  1313 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  1314 some limitations.  Blast_tac...
  1315   + ignores addss, addbefore, addafter; this restriction is intrinsic
  1316   + ignores elimination rules that don't have the correct format
  1317         (the conclusion MUST be a formula variable)
  1318   + ignores types, which can make HOL proofs fail
  1319   + rules must not require higher-order unification, e.g. apply_type in ZF
  1320     [message "Function Var's argument not a bound variable" relates to this]
  1321   + its proof strategy is more general but can actually be slower
  1322 
  1323 * substitution with equality assumptions no longer permutes other
  1324 assumptions;
  1325 
  1326 * minor changes in semantics of addafter (now called addaltern); renamed
  1327 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  1328 (and access functions for it);
  1329 
  1330 * improved combination of classical reasoner and simplifier:
  1331   + functions for handling clasimpsets
  1332   + improvement of addss: now the simplifier is called _after_ the
  1333     safe steps.
  1334   + safe variant of addss called addSss: uses safe simplifications
  1335     _during_ the safe steps. It is more complete as it allows multiple
  1336     instantiations of unknowns (e.g. with slow_tac).
  1337 
  1338 *** Simplifier ***
  1339 
  1340 * added interface for simplification procedures (functions that
  1341 produce *proven* rewrite rules on the fly, depending on current
  1342 redex);
  1343 
  1344 * ordering on terms as parameter (used for ordered rewriting);
  1345 
  1346 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  1347 
  1348 * the solver is now split into a safe and an unsafe part.
  1349 This should be invisible for the normal user, except that the
  1350 functions setsolver and addsolver have been renamed to setSolver and
  1351 addSolver; added safe_asm_full_simp_tac;
  1352 
  1353 
  1354 *** HOL ***
  1355 
  1356 * a generic induction tactic `induct_tac' which works for all datatypes and
  1357 also for type `nat';
  1358 
  1359 * a generic case distinction tactic `exhaust_tac' which works for all
  1360 datatypes and also for type `nat';
  1361 
  1362 * each datatype comes with a function `size';
  1363 
  1364 * patterns in case expressions allow tuple patterns as arguments to
  1365 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1366 
  1367 * primrec now also works with type nat;
  1368 
  1369 * recdef: a new declaration form, allows general recursive functions to be
  1370 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1371 
  1372 * the constant for negation has been renamed from "not" to "Not" to
  1373 harmonize with FOL, ZF, LK, etc.;
  1374 
  1375 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1376 infinite lists;
  1377 
  1378 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1379 
  1380 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1381 problems in commutative rings, using axiomatic type classes for + and *;
  1382 
  1383 * more examples in HOL/MiniML and HOL/Auth;
  1384 
  1385 * more default rewrite rules for quantifiers, union/intersection;
  1386 
  1387 * a new constant `arbitrary == @x.False';
  1388 
  1389 * HOLCF/IOA replaces old HOL/IOA;
  1390 
  1391 * HOLCF changes: derived all rules and arities
  1392   + axiomatic type classes instead of classes
  1393   + typedef instead of faking type definitions
  1394   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1395   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1396   + eliminated the types void, one, tr
  1397   + use unit lift and bool lift (with translations) instead of one and tr
  1398   + eliminated blift from Lift3.thy (use Def instead of blift)
  1399   all eliminated rules are derived as theorems --> no visible changes ;
  1400 
  1401 
  1402 *** ZF ***
  1403 
  1404 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1405 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1406 as ZF_cs addSIs [equalityI];
  1407 
  1408 
  1409 
  1410 New in Isabelle94-7 (November 96)
  1411 ---------------------------------
  1412 
  1413 * allowing negative levels (as offsets) in prlev and choplev;
  1414 
  1415 * super-linear speedup for large simplifications;
  1416 
  1417 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1418 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1419 FAIL); can suppress it using the command Delsimps (ex_simps @
  1420 all_simps); De Morgan laws are also now included, by default;
  1421 
  1422 * improved printing of ==>  :  ~:
  1423 
  1424 * new object-logic "Sequents" adds linear logic, while replacing LK
  1425 and Modal (thanks to Sara Kalvala);
  1426 
  1427 * HOL/Auth: correctness proofs for authentication protocols;
  1428 
  1429 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1430 examples on HOL/Auth);
  1431 
  1432 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1433 the rewriter and classical reasoner simultaneously;
  1434 
  1435 * function uresult no longer returns theorems in "standard" format;
  1436 regain previous version by: val uresult = standard o uresult;
  1437 
  1438 
  1439 
  1440 New in Isabelle94-6
  1441 -------------------
  1442 
  1443 * oracles -- these establish an interface between Isabelle and trusted
  1444 external reasoners, which may deliver results as theorems;
  1445 
  1446 * proof objects (in particular record all uses of oracles);
  1447 
  1448 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1449 
  1450 * "constdefs" section in theory files;
  1451 
  1452 * "primrec" section (HOL) no longer requires names;
  1453 
  1454 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1455 
  1456 
  1457 
  1458 New in Isabelle94-5
  1459 -------------------
  1460 
  1461 * reduced space requirements;
  1462 
  1463 * automatic HTML generation from theories;
  1464 
  1465 * theory files no longer require "..." (quotes) around most types;
  1466 
  1467 * new examples, including two proofs of the Church-Rosser theorem;
  1468 
  1469 * non-curried (1994) version of HOL is no longer distributed;
  1470 
  1471 
  1472 
  1473 New in Isabelle94-4
  1474 -------------------
  1475 
  1476 * greatly reduced space requirements;
  1477 
  1478 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1479 
  1480 * searchable theorem database (see the section "Retrieving theorems" on
  1481 page 8 of the Reference Manual);
  1482 
  1483 * new examples, including Grabczewski's monumental case study of the
  1484 Axiom of Choice;
  1485 
  1486 * The previous version of HOL renamed to Old_HOL;
  1487 
  1488 * The new version of HOL (previously called CHOL) uses a curried syntax
  1489 for functions.  Application looks like f a b instead of f(a,b);
  1490 
  1491 * Mutually recursive inductive definitions finally work in HOL;
  1492 
  1493 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1494 translates to the operator "split";
  1495 
  1496 
  1497 
  1498 New in Isabelle94-3
  1499 -------------------
  1500 
  1501 * new infix operator, addss, allowing the classical reasoner to
  1502 perform simplification at each step of its search.  Example:
  1503         fast_tac (cs addss ss)
  1504 
  1505 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1506 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1507 look like (a,b) instead of <a,b>;
  1508 
  1509 * PLEASE NOTE: CHOL will eventually replace HOL!
  1510 
  1511 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1512 It translates to the operator "split".  A new theory of integers is available;
  1513 
  1514 * In ZF, integer numerals now denote two's-complement binary integers.
  1515 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1516 
  1517 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1518 of the Axiom of Choice;
  1519 
  1520 
  1521 
  1522 New in Isabelle94-2
  1523 -------------------
  1524 
  1525 * Significantly faster resolution;
  1526 
  1527 * the different sections in a .thy file can now be mixed and repeated
  1528 freely;
  1529 
  1530 * Database of theorems for FOL, HOL and ZF.  New
  1531 commands including qed, qed_goal and bind_thm store theorems in the database.
  1532 
  1533 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1534 a given theory (thms_of), or find out what theory a theorem was proved in
  1535 (theory_of_thm);
  1536 
  1537 * Bugs fixed in the inductive definition and datatype packages;
  1538 
  1539 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1540 and HOL_dup_cs obsolete;
  1541 
  1542 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1543 have been removed;
  1544 
  1545 * Simpler definition of function space in ZF;
  1546 
  1547 * new results about cardinal and ordinal arithmetic in ZF;
  1548 
  1549 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1550 types;
  1551 
  1552 
  1553 $Id$