NEWS
author wenzelm
Thu Nov 11 11:27:31 1999 +0100 (1999-11-11)
changeset 8007 c29e27ee4933
parent 7986 9d319a76dbeb
child 8014 fdf1281a3d0c
permissions -rw-r--r--
header;
     1 
     2 Isabelle NEWS -- history user-relevant changes
     3 ==============================================
     4 
     5 New in this Isabelle version
     6 ----------------------------
     7 
     8 
     9 New in Isabelle99 (October 1999)
    10 --------------------------------
    11 
    12 *** Overview of INCOMPATIBILITIES (see below for more details) ***
    13 
    14 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
    15 are no longer simplified.  (This allows the simplifier to unfold recursive
    16 functional programs.)  To restore the old behaviour, declare
    17 
    18     Delcongs [if_weak_cong];
    19 
    20 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
    21 complement;
    22 
    23 * HOL: the predicate "inj" is now defined by translation to "inj_on";
    24 
    25 * HOL/datatype: mutual_induct_tac no longer exists --
    26   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
    27 
    28 * HOL/typedef: fixed type inference for representing set; type
    29 arguments now have to occur explicitly on the rhs as type constraints;
    30 
    31 * ZF: The con_defs part of an inductive definition may no longer refer
    32 to constants declared in the same theory;
    33 
    34 * HOL, ZF: the function mk_cases, generated by the inductive
    35 definition package, has lost an argument.  To simplify its result, it
    36 uses the default simpset instead of a supplied list of theorems.
    37 
    38 * HOL/List: the constructors of type list are now Nil and Cons;
    39 
    40 * Simplifier: the type of the infix ML functions
    41 	setSSolver addSSolver setSolver addSolver
    42 is now  simpset * solver -> simpset  where `solver' is a new abstract type
    43 for packaging solvers. A solver is created via
    44 	mk_solver: string -> (thm list -> int -> tactic) -> solver
    45 where the string argument is only a comment.
    46 
    47 
    48 *** Proof tools ***
    49 
    50 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
    51 decision procedure for linear arithmetic. Currently it is used for
    52 types `nat', `int', and `real' in HOL (see below); it can, should and
    53 will be instantiated for other types and logics as well.
    54 
    55 * The simplifier now accepts rewrite rules with flexible heads, eg
    56      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
    57   They are applied like any rule with a non-pattern lhs, i.e. by first-order
    58   matching.
    59 
    60 
    61 *** General ***
    62 
    63 * New Isabelle/Isar subsystem provides an alternative to traditional
    64 tactical theorem proving; together with the ProofGeneral/isar user
    65 interface it offers an interactive environment for developing human
    66 readable proof documents (Isar == Intelligible semi-automated
    67 reasoning); for further information see isatool doc isar-ref,
    68 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
    69 
    70 * improved presentation of theories: better HTML markup (including
    71 colors), graph views in several sizes; isatool usedir now provides a
    72 proper interface for user theories (via -P option); actual document
    73 preparation based on (PDF)LaTeX is available as well (for new-style
    74 theories only); see isatool doc system for more information;
    75 
    76 * native support for Proof General, both for classic Isabelle and
    77 Isabelle/Isar;
    78 
    79 * ML function thm_deps visualizes dependencies of theorems and lemmas,
    80 using the graph browser tool;
    81 
    82 * Isabelle manuals now also available as PDF;
    83 
    84 * theory loader rewritten from scratch (may not be fully
    85 bug-compatible); old loadpath variable has been replaced by show_path,
    86 add_path, del_path, reset_path functions; new operations such as
    87 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
    88 isatool doc ref);
    89 
    90 * improved isatool install: option -k creates KDE application icon,
    91 option -p DIR installs standalone binaries;
    92 
    93 * added ML_PLATFORM setting (useful for cross-platform installations);
    94 more robust handling of platform specific ML images for SML/NJ;
    95 
    96 * the settings environment is now statically scoped, i.e. it is never
    97 created again in sub-processes invoked from isabelle, isatool, or
    98 Isabelle;
    99 
   100 * path element specification '~~' refers to '$ISABELLE_HOME';
   101 
   102 * in locales, the "assumes" and "defines" parts may be omitted if
   103 empty;
   104 
   105 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   106 long arrows);
   107 
   108 * new print_mode "HTML";
   109 
   110 * new flag show_tags controls display of tags of theorems (which are
   111 basically just comments that may be attached by some tools);
   112 
   113 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   114 mode and goal output format:
   115 
   116 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   117 244c244
   118 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   119 ---
   120 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   121 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   122 181c181
   123 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   124 ---
   125 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   126 
   127 * function bind_thms stores lists of theorems (cf. bind_thm);
   128 
   129 * new shorthand tactics ftac, eatac, datac, fatac;
   130 
   131 * qed (and friends) now accept "" as result name; in that case the
   132 theorem is not stored, but proper checks and presentation of the
   133 result still apply;
   134 
   135 * theorem database now also indexes constants "Trueprop", "all",
   136 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   137 
   138 
   139 *** HOL ***
   140 
   141 ** HOL arithmetic **
   142 
   143 * There are now decision procedures for linear arithmetic over nat and
   144 int:
   145 
   146 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   147 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   148 are treated as atomic; subformulae not involving type `nat' or `int'
   149 are ignored; quantified subformulae are ignored unless they are
   150 positive universal or negative existential. The tactic has to be
   151 invoked by hand and can be a little bit slow. In particular, the
   152 running time is exponential in the number of occurrences of `min' and
   153 `max', and `-' on `nat'.
   154 
   155 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   156 (negated) (in)equalities among the premises and the conclusion into
   157 account (i.e. no compound formulae) and does not know about `min' and
   158 `max', and `-' on `nat'. It is fast and is used automatically by the
   159 simplifier.
   160 
   161 NB: At the moment, these decision procedures do not cope with mixed
   162 nat/int formulae where the two parts interact, such as `m < n ==>
   163 int(m) < int(n)'.
   164 
   165 * HOL/Numeral provides a generic theory of numerals (encoded
   166 efficiently as bit strings); setup for types nat/int/real is in place;
   167 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   168 int, existing theories and proof scripts may require a few additional
   169 type constraints;
   170 
   171 * integer division and remainder can now be performed on constant
   172 arguments;
   173 
   174 * many properties of integer multiplication, division and remainder
   175 are now available;
   176 
   177 * An interface to the Stanford Validity Checker (SVC) is available through the
   178 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   179 are proved automatically.  SVC must be installed separately, and its results
   180 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   181 invocation of the underlying oracle).  For SVC see
   182   http://verify.stanford.edu/SVC
   183 
   184 * IsaMakefile: the HOL-Real target now builds an actual image;
   185 
   186 
   187 ** HOL misc **
   188 
   189 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   190 (in Isabelle/Isar) -- by Gertrud Bauer;
   191 
   192 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   193 analysis for assembly languages with subtypes;
   194 
   195 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   196 -- avoids syntactic ambiguities and treats state, transition, and
   197 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   198 changed syntax and (many) tactics;
   199 
   200 * HOL/inductive: Now also handles more general introduction rules such
   201   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
   202   theorems are now maintained within the theory (maintained via the
   203   "mono" attribute);
   204 
   205 * HOL/datatype: Now also handles arbitrarily branching datatypes
   206   (using function types) such as
   207 
   208   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
   209 
   210 * HOL/record: record_simproc (part of the default simpset) takes care
   211 of selectors applied to updated records; record_split_tac is no longer
   212 part of the default claset; update_defs may now be removed from the
   213 simpset in many cases; COMPATIBILITY: old behavior achieved by
   214 
   215   claset_ref () := claset() addSWrapper record_split_wrapper;
   216   Delsimprocs [record_simproc]
   217 
   218 * HOL/typedef: fixed type inference for representing set; type
   219 arguments now have to occur explicitly on the rhs as type constraints;
   220 
   221 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
   222 names rather than an ML expression;
   223 
   224 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
   225 supplied later.  Program schemes can be defined, such as
   226     "While B C s = (if B s then While B C (C s) else s)"
   227 where the well-founded relation can be chosen after B and C have been given.
   228 
   229 * HOL/List: the constructors of type list are now Nil and Cons;
   230 INCOMPATIBILITY: while [] and infix # syntax is still there, of
   231 course, ML tools referring to List.list.op # etc. have to be adapted;
   232 
   233 * HOL_quantifiers flag superseded by "HOL" print mode, which is
   234 disabled by default; run isabelle with option -m HOL to get back to
   235 the original Gordon/HOL-style output;
   236 
   237 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
   238 ALL x<=y. P, EX x<y. P, EX x<=y. P;
   239 
   240 * HOL basic syntax simplified (more orthogonal): all variants of
   241 All/Ex now support plain / symbolic / HOL notation; plain syntax for
   242 Eps operator is provided as well: "SOME x. P[x]";
   243 
   244 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
   245 
   246 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
   247 thus available for user theories;
   248 
   249 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
   250 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
   251 time;
   252 
   253 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
   254 several times and then mp;
   255 
   256 
   257 *** LK ***
   258 
   259 * the notation <<...>> is now available as a notation for sequences of
   260 formulas;
   261 
   262 * the simplifier is now installed
   263 
   264 * the axiom system has been generalized (thanks to Soren Heilmann) 
   265 
   266 * the classical reasoner now has a default rule database
   267 
   268 
   269 *** ZF ***
   270 
   271 * new primrec section allows primitive recursive functions to be given
   272 directly (as in HOL) over datatypes and the natural numbers;
   273 
   274 * new tactics induct_tac and exhaust_tac for induction (or case
   275 analysis) over datatypes and the natural numbers;
   276 
   277 * the datatype declaration of type T now defines the recursor T_rec;
   278 
   279 * simplification automatically does freeness reasoning for datatype
   280 constructors;
   281 
   282 * automatic type-inference, with AddTCs command to insert new
   283 type-checking rules;
   284 
   285 * datatype introduction rules are now added as Safe Introduction rules
   286 to the claset;
   287 
   288 * the syntax "if P then x else y" is now available in addition to
   289 if(P,x,y);
   290 
   291 
   292 *** Internal programming interfaces ***
   293 
   294 * tuned simplifier trace output; new flag debug_simp;
   295 
   296 * structures Vartab / Termtab (instances of TableFun) offer efficient
   297 tables indexed by indexname_ord / term_ord (compatible with aconv);
   298 
   299 * AxClass.axclass_tac lost the theory argument;
   300 
   301 * tuned current_goals_markers semantics: begin / end goal avoids
   302 printing empty lines;
   303 
   304 * removed prs and prs_fn hook, which was broken because it did not
   305 include \n in its semantics, forcing writeln to add one
   306 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
   307 string -> unit if you really want to output text without newline;
   308 
   309 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
   310 plain output, interface builders may have to enable 'isabelle_font'
   311 mode to get Isabelle font glyphs as before;
   312 
   313 * refined token_translation interface; INCOMPATIBILITY: output length
   314 now of type real instead of int;
   315 
   316 * theory loader actions may be traced via new ThyInfo.add_hook
   317 interface (see src/Pure/Thy/thy_info.ML); example application: keep
   318 your own database of information attached to *whole* theories -- as
   319 opposed to intra-theory data slots offered via TheoryDataFun;
   320 
   321 * proper handling of dangling sort hypotheses (at last!);
   322 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
   323 extra sort hypotheses that can be witnessed from the type signature;
   324 the force_strip_shyps flag is gone, any remaining shyps are simply
   325 left in the theorem (with a warning issued by strip_shyps_warning);
   326 
   327 
   328 
   329 New in Isabelle98-1 (October 1998)
   330 ----------------------------------
   331 
   332 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   333 
   334 * several changes of automated proof tools;
   335 
   336 * HOL: major changes to the inductive and datatype packages, including
   337 some minor incompatibilities of theory syntax;
   338 
   339 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
   340 called `inj_on';
   341 
   342 * HOL: removed duplicate thms in Arith:
   343   less_imp_add_less  should be replaced by  trans_less_add1
   344   le_imp_add_le      should be replaced by  trans_le_add1
   345 
   346 * HOL: unary minus is now overloaded (new type constraints may be
   347 required);
   348 
   349 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
   350 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
   351 now taken as an integer constant.
   352 
   353 * Pure: ML function 'theory_of' renamed to 'theory';
   354 
   355 
   356 *** Proof tools ***
   357 
   358 * Simplifier:
   359   1. Asm_full_simp_tac is now more aggressive.
   360      1. It will sometimes reorient premises if that increases their power to
   361         simplify.
   362      2. It does no longer proceed strictly from left to right but may also
   363         rotate premises to achieve further simplification.
   364      For compatibility reasons there is now Asm_lr_simp_tac which is like the
   365      old Asm_full_simp_tac in that it does not rotate premises.
   366   2. The simplifier now knows a little bit about nat-arithmetic.
   367 
   368 * Classical reasoner: wrapper mechanism for the classical reasoner now
   369 allows for selected deletion of wrappers, by introduction of names for
   370 wrapper functionals.  This implies that addbefore, addSbefore,
   371 addaltern, and addSaltern now take a pair (name, tactic) as argument,
   372 and that adding two tactics with the same name overwrites the first
   373 one (emitting a warning).
   374   type wrapper = (int -> tactic) -> (int -> tactic)
   375   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
   376   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
   377   delWrapper, delSWrapper: claset *  string            -> claset
   378   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
   379 
   380 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
   381 semantics; addbefore now affects only the unsafe part of step_tac
   382 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
   383 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
   384 by Force_tac;
   385 
   386 * Classical reasoner: setwrapper to setWrapper and compwrapper to
   387 compWrapper; added safe wrapper (and access functions for it);
   388 
   389 * HOL/split_all_tac is now much faster and fails if there is nothing
   390 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
   391 and the names of the automatically generated variables have changed.
   392 split_all_tac has moved within claset() from unsafe wrappers to safe
   393 wrappers, which means that !!-bound variables are split much more
   394 aggressively, and safe_tac and clarify_tac now split such variables.
   395 If this splitting is not appropriate, use delSWrapper "split_all_tac".
   396 Note: the same holds for record_split_tac, which does the job of
   397 split_all_tac for record fields.
   398 
   399 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
   400 permanently to the default simpset using Addsplits just like
   401 Addsimps. They can be removed via Delsplits just like
   402 Delsimps. Lower-case versions are also available.
   403 
   404 * HOL/Simplifier: The rule split_if is now part of the default
   405 simpset. This means that the simplifier will eliminate all occurrences
   406 of if-then-else in the conclusion of a goal. To prevent this, you can
   407 either remove split_if completely from the default simpset by
   408 `Delsplits [split_if]' or remove it in a specific call of the
   409 simplifier using `... delsplits [split_if]'.  You can also add/delete
   410 other case splitting rules to/from the default simpset: every datatype
   411 generates suitable rules `split_t_case' and `split_t_case_asm' (where
   412 t is the name of the datatype).
   413 
   414 * Classical reasoner / Simplifier combination: new force_tac (and
   415 derivatives Force_tac, force) combines rewriting and classical
   416 reasoning (and whatever other tools) similarly to auto_tac, but is
   417 aimed to solve the given subgoal completely.
   418 
   419 
   420 *** General ***
   421 
   422 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
   423 and `goalw': the theory is no longer needed as an explicit argument -
   424 the current theory context is used; assumptions are no longer returned
   425 at the ML-level unless one of them starts with ==> or !!; it is
   426 recommended to convert to these new commands using isatool fixgoal
   427 (backup your sources first!);
   428 
   429 * new top-level commands 'thm' and 'thms' for retrieving theorems from
   430 the current theory context, and 'theory' to lookup stored theories;
   431 
   432 * new theory section 'locale' for declaring constants, assumptions and
   433 definitions that have local scope;
   434 
   435 * new theory section 'nonterminals' for purely syntactic types;
   436 
   437 * new theory section 'setup' for generic ML setup functions
   438 (e.g. package initialization);
   439 
   440 * the distribution now includes Isabelle icons: see
   441 lib/logo/isabelle-{small,tiny}.xpm;
   442 
   443 * isatool install - install binaries with absolute references to
   444 ISABELLE_HOME/bin;
   445 
   446 * isatool logo -- create instances of the Isabelle logo (as EPS);
   447 
   448 * print mode 'emacs' reserved for Isamode;
   449 
   450 * support multiple print (ast) translations per constant name;
   451 
   452 * theorems involving oracles are now printed with a suffixed [!];
   453 
   454 
   455 *** HOL ***
   456 
   457 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
   458 
   459 * HOL/inductive package reorganized and improved: now supports mutual
   460 definitions such as
   461 
   462   inductive EVEN ODD
   463     intrs
   464       null "0 : EVEN"
   465       oddI "n : EVEN ==> Suc n : ODD"
   466       evenI "n : ODD ==> Suc n : EVEN"
   467 
   468 new theorem list "elims" contains an elimination rule for each of the
   469 recursive sets; inductive definitions now handle disjunctive premises
   470 correctly (also ZF);
   471 
   472 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   473 "mutual_induct" no longer exists - the induction rule is always
   474 contained in "induct";
   475 
   476 
   477 * HOL/datatype package re-implemented and greatly improved: now
   478 supports mutually recursive datatypes such as
   479 
   480   datatype
   481     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
   482             | SUM ('a aexp) ('a aexp)
   483             | DIFF ('a aexp) ('a aexp)
   484             | NUM 'a
   485   and
   486     'a bexp = LESS ('a aexp) ('a aexp)
   487             | AND ('a bexp) ('a bexp)
   488             | OR ('a bexp) ('a bexp)
   489 
   490 as well as indirectly recursive datatypes such as
   491 
   492   datatype
   493     ('a, 'b) term = Var 'a
   494                   | App 'b ((('a, 'b) term) list)
   495 
   496 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
   497 induction on mutually / indirectly recursive datatypes.
   498 
   499 Primrec equations are now stored in theory and can be accessed via
   500 <function_name>.simps.
   501 
   502 INCOMPATIBILITIES:
   503 
   504   - Theories using datatypes must now have theory Datatype as an
   505     ancestor.
   506   - The specific <typename>.induct_tac no longer exists - use the
   507     generic induct_tac instead.
   508   - natE has been renamed to nat.exhaust - use exhaust_tac
   509     instead of res_inst_tac ... natE. Note that the variable
   510     names in nat.exhaust differ from the names in natE, this
   511     may cause some "fragile" proofs to fail.
   512   - The theorems split_<typename>_case and split_<typename>_case_asm
   513     have been renamed to <typename>.split and <typename>.split_asm.
   514   - Since default sorts of type variables are now handled correctly,
   515     some datatype definitions may have to be annotated with explicit
   516     sort constraints.
   517   - Primrec definitions no longer require function name and type
   518     of recursive argument.
   519 
   520 Consider using isatool fixdatatype to adapt your theories and proof
   521 scripts to the new package (backup your sources first!).
   522 
   523 
   524 * HOL/record package: considerably improved implementation; now
   525 includes concrete syntax for record types, terms, updates; theorems
   526 for surjective pairing and splitting !!-bound record variables; proof
   527 support is as follows:
   528 
   529   1) standard conversions (selectors or updates applied to record
   530 constructor terms) are part of the standard simpset;
   531 
   532   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
   533 made part of standard simpset and claset via addIffs;
   534 
   535   3) a tactic for record field splitting (record_split_tac) is part of
   536 the standard claset (addSWrapper);
   537 
   538 To get a better idea about these rules you may retrieve them via
   539 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
   540 the name of your record type.
   541 
   542 The split tactic 3) conceptually simplifies by the following rule:
   543 
   544   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
   545 
   546 Thus any record variable that is bound by meta-all will automatically
   547 blow up into some record constructor term, consequently the
   548 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
   549 solve record problems automatically.
   550 
   551 
   552 * reorganized the main HOL image: HOL/Integ and String loaded by
   553 default; theory Main includes everything;
   554 
   555 * automatic simplification of integer sums and comparisons, using cancellation;
   556 
   557 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
   558 
   559 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
   560 
   561 * many new identities for unions, intersections, set difference, etc.;
   562 
   563 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
   564 called split_if, split_split, split_sum_case and split_nat_case (to go
   565 with add/delsplits);
   566 
   567 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
   568 (?x::unit) = (); this is made part of the default simpset, which COULD
   569 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
   570 'Delsimprocs [unit_eq_proc];' as last resort); also note that
   571 unit_abs_eta_conv is added in order to counter the effect of
   572 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
   573 %u.f();
   574 
   575 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
   576 makes more sense);
   577 
   578 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   579   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   580   disjointness reasoning but breaking a few old proofs.
   581 
   582 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
   583 to 'converse' from 'inverse' (for compatibility with ZF and some
   584 literature);
   585 
   586 * HOL/recdef can now declare non-recursive functions, with {} supplied as
   587 the well-founded relation;
   588 
   589 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
   590     Compl A.  The "Compl" syntax remains available as input syntax for this
   591     release ONLY.
   592 
   593 * HOL/Update: new theory of function updates:
   594     f(a:=b) == %x. if x=a then b else f x
   595 may also be iterated as in f(a:=b,c:=d,...);
   596 
   597 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
   598 
   599 * HOL/List:
   600   - new function list_update written xs[i:=v] that updates the i-th
   601     list position. May also be iterated as in xs[i:=a,j:=b,...].
   602   - new function `upt' written [i..j(] which generates the list
   603     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
   604     bound write [i..j], which is a shorthand for [i..j+1(].
   605   - new lexicographic orderings and corresponding wellfoundedness theorems.
   606 
   607 * HOL/Arith:
   608   - removed 'pred' (predecessor) function;
   609   - generalized some theorems about n-1;
   610   - many new laws about "div" and "mod";
   611   - new laws about greatest common divisors (see theory ex/Primes);
   612 
   613 * HOL/Relation: renamed the relational operator r^-1 "converse"
   614 instead of "inverse";
   615 
   616 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
   617   of the multiset ordering;
   618 
   619 * directory HOL/Real: a construction of the reals using Dedekind cuts
   620   (not included by default);
   621 
   622 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
   623 
   624 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
   625   programs, i.e. different program variables may have different types.
   626 
   627 * calling (stac rew i) now fails if "rew" has no effect on the goal
   628   [previously, this check worked only if the rewrite rule was unconditional]
   629   Now rew can involve either definitions or equalities (either == or =).
   630 
   631 
   632 *** ZF ***
   633 
   634 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
   635   only the theorems proved on ZF.ML;
   636 
   637 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   638   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   639   disjointness reasoning but breaking a few old proofs.
   640 
   641 * ZF/Update: new theory of function updates
   642     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
   643   may also be iterated as in f(a:=b,c:=d,...);
   644 
   645 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
   646 
   647 * calling (stac rew i) now fails if "rew" has no effect on the goal
   648   [previously, this check worked only if the rewrite rule was unconditional]
   649   Now rew can involve either definitions or equalities (either == or =).
   650 
   651 * case_tac provided for compatibility with HOL
   652     (like the old excluded_middle_tac, but with subgoals swapped)
   653 
   654 
   655 *** Internal programming interfaces ***
   656 
   657 * Pure: several new basic modules made available for general use, see
   658 also src/Pure/README;
   659 
   660 * improved the theory data mechanism to support encapsulation (data
   661 kind name replaced by private Object.kind, acting as authorization
   662 key); new type-safe user interface via functor TheoryDataFun; generic
   663 print_data function becomes basically useless;
   664 
   665 * removed global_names compatibility flag -- all theory declarations
   666 are qualified by default;
   667 
   668 * module Pure/Syntax now offers quote / antiquote translation
   669 functions (useful for Hoare logic etc. with implicit dependencies);
   670 see HOL/ex/Antiquote for an example use;
   671 
   672 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
   673 cterm -> thm;
   674 
   675 * new tactical CHANGED_GOAL for checking that a tactic modifies a
   676 subgoal;
   677 
   678 * Display.print_goals function moved to Locale.print_goals;
   679 
   680 * standard print function for goals supports current_goals_markers
   681 variable for marking begin of proof, end of proof, start of goal; the
   682 default is ("", "", ""); setting current_goals_markers := ("<proof>",
   683 "</proof>", "<goal>") causes SGML like tagged proof state printing,
   684 for example;
   685 
   686 
   687 
   688 New in Isabelle98 (January 1998)
   689 --------------------------------
   690 
   691 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   692 
   693 * changed lexical syntax of terms / types: dots made part of long
   694 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
   695 
   696 * simpset (and claset) reference variable replaced by functions
   697 simpset / simpset_ref;
   698 
   699 * no longer supports theory aliases (via merge) and non-trivial
   700 implicit merge of thms' signatures;
   701 
   702 * most internal names of constants changed due to qualified names;
   703 
   704 * changed Pure/Sequence interface (see Pure/seq.ML);
   705 
   706 
   707 *** General Changes ***
   708 
   709 * hierachically structured name spaces (for consts, types, axms, thms
   710 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
   711 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
   712 isatool fixdots ensures space after dots (e.g. "%x. x"); set
   713 long_names for fully qualified output names; NOTE: ML programs
   714 (special tactics, packages etc.) referring to internal names may have
   715 to be adapted to cope with fully qualified names; in case of severe
   716 backward campatibility problems try setting 'global_names' at compile
   717 time to have enrything declared within a flat name space; one may also
   718 fine tune name declarations in theories via the 'global' and 'local'
   719 section;
   720 
   721 * reimplemented the implicit simpset and claset using the new anytype
   722 data filed in signatures; references simpset:simpset ref etc. are
   723 replaced by functions simpset:unit->simpset and
   724 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
   725 to patch your ML files accordingly;
   726 
   727 * HTML output now includes theory graph data for display with Java
   728 applet or isatool browser; data generated automatically via isatool
   729 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
   730 
   731 * defs may now be conditional; improved rewrite_goals_tac to handle
   732 conditional equations;
   733 
   734 * defs now admits additional type arguments, using TYPE('a) syntax;
   735 
   736 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
   737 creates a new theory node; implicit merge of thms' signatures is
   738 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
   739 transfer:theory->thm->thm in (rare) cases;
   740 
   741 * improved handling of draft signatures / theories; draft thms (and
   742 ctyps, cterms) are automatically promoted to real ones;
   743 
   744 * slightly changed interfaces for oracles: admit many per theory, named
   745 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
   746 
   747 * print_goals: optional output of const types (set show_consts and
   748 show_types);
   749 
   750 * improved output of warnings (###) and errors (***);
   751 
   752 * subgoal_tac displays a warning if the new subgoal has type variables;
   753 
   754 * removed old README and Makefiles;
   755 
   756 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
   757 
   758 * removed obsolete init_pps and init_database;
   759 
   760 * deleted the obsolete tactical STATE, which was declared by
   761     fun STATE tacfun st = tacfun st st;
   762 
   763 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
   764 (which abbreviates $HOME);
   765 
   766 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
   767 use isatool fixseq to adapt your ML programs (this works for fully
   768 qualified references to the Sequence structure only!);
   769 
   770 * use_thy no longer requires writable current directory; it always
   771 reloads .ML *and* .thy file, if either one is out of date;
   772 
   773 
   774 *** Classical Reasoner ***
   775 
   776 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
   777 tactics that use classical reasoning to simplify a subgoal without
   778 splitting it into several subgoals;
   779 
   780 * Safe_tac: like safe_tac but uses the default claset;
   781 
   782 
   783 *** Simplifier ***
   784 
   785 * added simplification meta rules:
   786     (asm_)(full_)simplify: simpset -> thm -> thm;
   787 
   788 * simplifier.ML no longer part of Pure -- has to be loaded by object
   789 logics (again);
   790 
   791 * added prems argument to simplification procedures;
   792 
   793 * HOL, FOL, ZF: added infix function `addsplits':
   794   instead of `<simpset> setloop (split_tac <thms>)'
   795   you can simply write `<simpset> addsplits <thms>'
   796 
   797 
   798 *** Syntax ***
   799 
   800 * TYPE('a) syntax for type reflection terms;
   801 
   802 * no longer handles consts with name "" -- declare as 'syntax' instead;
   803 
   804 * pretty printer: changed order of mixfix annotation preference (again!);
   805 
   806 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
   807 
   808 
   809 *** HOL ***
   810 
   811 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
   812   with `addloop' of the simplifier to faciliate case splitting in premises.
   813 
   814 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
   815 
   816 * HOL/Auth: new protocol proofs including some for the Internet
   817   protocol TLS;
   818 
   819 * HOL/Map: new theory of `maps' a la VDM;
   820 
   821 * HOL/simplifier: simplification procedures nat_cancel_sums for
   822 cancelling out common nat summands from =, <, <= (in)equalities, or
   823 differences; simplification procedures nat_cancel_factor for
   824 cancelling common factor from =, <, <= (in)equalities over natural
   825 sums; nat_cancel contains both kinds of procedures, it is installed by
   826 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
   827 
   828 * HOL/simplifier: terms of the form
   829   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
   830   are rewritten to
   831   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
   832   and those of the form
   833   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
   834   are rewritten to
   835   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
   836 
   837 * HOL/datatype
   838   Each datatype `t' now comes with a theorem `split_t_case' of the form
   839 
   840   P(t_case f1 ... fn x) =
   841      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
   842         ...
   843        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
   844      )
   845 
   846   and a theorem `split_t_case_asm' of the form
   847 
   848   P(t_case f1 ... fn x) =
   849     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
   850         ...
   851        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
   852      )
   853   which can be added to a simpset via `addsplits'. The existing theorems
   854   expand_list_case and expand_option_case have been renamed to
   855   split_list_case and split_option_case.
   856 
   857 * HOL/Arithmetic:
   858   - `pred n' is automatically converted to `n-1'.
   859     Users are strongly encouraged not to use `pred' any longer,
   860     because it will disappear altogether at some point.
   861   - Users are strongly encouraged to write "0 < n" rather than
   862     "n ~= 0". Theorems and proof tools have been modified towards this
   863     `standard'.
   864 
   865 * HOL/Lists:
   866   the function "set_of_list" has been renamed "set" (and its theorems too);
   867   the function "nth" now takes its arguments in the reverse order and
   868   has acquired the infix notation "!" as in "xs!n".
   869 
   870 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
   871 
   872 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
   873   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
   874 
   875 * HOL/record: extensible records with schematic structural subtyping
   876 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
   877 still lacks various theorems and concrete record syntax;
   878 
   879 
   880 *** HOLCF ***
   881 
   882 * removed "axioms" and "generated by" sections;
   883 
   884 * replaced "ops" section by extended "consts" section, which is capable of
   885   handling the continuous function space "->" directly;
   886 
   887 * domain package:
   888   . proves theorems immediately and stores them in the theory,
   889   . creates hierachical name space,
   890   . now uses normal mixfix annotations (instead of cinfix...),
   891   . minor changes to some names and values (for consistency),
   892   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
   893   . separator between mutual domain defs: changed "," to "and",
   894   . improved handling of sort constraints;  now they have to
   895     appear on the left-hand side of the equations only;
   896 
   897 * fixed LAM <x,y,zs>.b syntax;
   898 
   899 * added extended adm_tac to simplifier in HOLCF -- can now discharge
   900 adm (%x. P (t x)), where P is chainfinite and t continuous;
   901 
   902 
   903 *** FOL and ZF ***
   904 
   905 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
   906   with `addloop' of the simplifier to faciliate case splitting in premises.
   907 
   908 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
   909 in HOL, they strip ALL and --> from proved theorems;
   910 
   911 
   912 
   913 New in Isabelle94-8 (May 1997)
   914 ------------------------------
   915 
   916 *** General Changes ***
   917 
   918 * new utilities to build / run / maintain Isabelle etc. (in parts
   919 still somewhat experimental); old Makefiles etc. still functional;
   920 
   921 * new 'Isabelle System Manual';
   922 
   923 * INSTALL text, together with ./configure and ./build scripts;
   924 
   925 * reimplemented type inference for greater efficiency, better error
   926 messages and clean internal interface;
   927 
   928 * prlim command for dealing with lots of subgoals (an easier way of
   929 setting goals_limit);
   930 
   931 
   932 *** Syntax ***
   933 
   934 * supports alternative (named) syntax tables (parser and pretty
   935 printer); internal interface is provided by add_modesyntax(_i);
   936 
   937 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
   938 be used in conjunction with the Isabelle symbol font; uses the
   939 "symbols" syntax table;
   940 
   941 * added token_translation interface (may translate name tokens in
   942 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
   943 the current print_mode); IMPORTANT: user print translation functions
   944 are responsible for marking newly introduced bounds
   945 (Syntax.mark_boundT);
   946 
   947 * token translations for modes "xterm" and "xterm_color" that display
   948 names in bold, underline etc. or colors (which requires a color
   949 version of xterm);
   950 
   951 * infixes may now be declared with names independent of their syntax;
   952 
   953 * added typed_print_translation (like print_translation, but may
   954 access type of constant);
   955 
   956 
   957 *** Classical Reasoner ***
   958 
   959 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
   960 some limitations.  Blast_tac...
   961   + ignores addss, addbefore, addafter; this restriction is intrinsic
   962   + ignores elimination rules that don't have the correct format
   963         (the conclusion MUST be a formula variable)
   964   + ignores types, which can make HOL proofs fail
   965   + rules must not require higher-order unification, e.g. apply_type in ZF
   966     [message "Function Var's argument not a bound variable" relates to this]
   967   + its proof strategy is more general but can actually be slower
   968 
   969 * substitution with equality assumptions no longer permutes other
   970 assumptions;
   971 
   972 * minor changes in semantics of addafter (now called addaltern); renamed
   973 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
   974 (and access functions for it);
   975 
   976 * improved combination of classical reasoner and simplifier:
   977   + functions for handling clasimpsets
   978   + improvement of addss: now the simplifier is called _after_ the
   979     safe steps.
   980   + safe variant of addss called addSss: uses safe simplifications
   981     _during_ the safe steps. It is more complete as it allows multiple
   982     instantiations of unknowns (e.g. with slow_tac).
   983 
   984 *** Simplifier ***
   985 
   986 * added interface for simplification procedures (functions that
   987 produce *proven* rewrite rules on the fly, depending on current
   988 redex);
   989 
   990 * ordering on terms as parameter (used for ordered rewriting);
   991 
   992 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
   993 
   994 * the solver is now split into a safe and an unsafe part.
   995 This should be invisible for the normal user, except that the
   996 functions setsolver and addsolver have been renamed to setSolver and
   997 addSolver; added safe_asm_full_simp_tac;
   998 
   999 
  1000 *** HOL ***
  1001 
  1002 * a generic induction tactic `induct_tac' which works for all datatypes and
  1003 also for type `nat';
  1004 
  1005 * a generic case distinction tactic `exhaust_tac' which works for all
  1006 datatypes and also for type `nat';
  1007 
  1008 * each datatype comes with a function `size';
  1009 
  1010 * patterns in case expressions allow tuple patterns as arguments to
  1011 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1012 
  1013 * primrec now also works with type nat;
  1014 
  1015 * recdef: a new declaration form, allows general recursive functions to be
  1016 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1017 
  1018 * the constant for negation has been renamed from "not" to "Not" to
  1019 harmonize with FOL, ZF, LK, etc.;
  1020 
  1021 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1022 infinite lists;
  1023 
  1024 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1025 
  1026 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1027 problems in commutative rings, using axiomatic type classes for + and *;
  1028 
  1029 * more examples in HOL/MiniML and HOL/Auth;
  1030 
  1031 * more default rewrite rules for quantifiers, union/intersection;
  1032 
  1033 * a new constant `arbitrary == @x.False';
  1034 
  1035 * HOLCF/IOA replaces old HOL/IOA;
  1036 
  1037 * HOLCF changes: derived all rules and arities
  1038   + axiomatic type classes instead of classes
  1039   + typedef instead of faking type definitions
  1040   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1041   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1042   + eliminated the types void, one, tr
  1043   + use unit lift and bool lift (with translations) instead of one and tr
  1044   + eliminated blift from Lift3.thy (use Def instead of blift)
  1045   all eliminated rules are derived as theorems --> no visible changes ;
  1046 
  1047 
  1048 *** ZF ***
  1049 
  1050 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1051 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1052 as ZF_cs addSIs [equalityI];
  1053 
  1054 
  1055 
  1056 New in Isabelle94-7 (November 96)
  1057 ---------------------------------
  1058 
  1059 * allowing negative levels (as offsets) in prlev and choplev;
  1060 
  1061 * super-linear speedup for large simplifications;
  1062 
  1063 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1064 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1065 FAIL); can suppress it using the command Delsimps (ex_simps @
  1066 all_simps); De Morgan laws are also now included, by default;
  1067 
  1068 * improved printing of ==>  :  ~:
  1069 
  1070 * new object-logic "Sequents" adds linear logic, while replacing LK
  1071 and Modal (thanks to Sara Kalvala);
  1072 
  1073 * HOL/Auth: correctness proofs for authentication protocols;
  1074 
  1075 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1076 examples on HOL/Auth);
  1077 
  1078 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1079 the rewriter and classical reasoner simultaneously;
  1080 
  1081 * function uresult no longer returns theorems in "standard" format;
  1082 regain previous version by: val uresult = standard o uresult;
  1083 
  1084 
  1085 
  1086 New in Isabelle94-6
  1087 -------------------
  1088 
  1089 * oracles -- these establish an interface between Isabelle and trusted
  1090 external reasoners, which may deliver results as theorems;
  1091 
  1092 * proof objects (in particular record all uses of oracles);
  1093 
  1094 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1095 
  1096 * "constdefs" section in theory files;
  1097 
  1098 * "primrec" section (HOL) no longer requires names;
  1099 
  1100 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1101 
  1102 
  1103 
  1104 New in Isabelle94-5
  1105 -------------------
  1106 
  1107 * reduced space requirements;
  1108 
  1109 * automatic HTML generation from theories;
  1110 
  1111 * theory files no longer require "..." (quotes) around most types;
  1112 
  1113 * new examples, including two proofs of the Church-Rosser theorem;
  1114 
  1115 * non-curried (1994) version of HOL is no longer distributed;
  1116 
  1117 
  1118 
  1119 New in Isabelle94-4
  1120 -------------------
  1121 
  1122 * greatly reduced space requirements;
  1123 
  1124 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1125 
  1126 * searchable theorem database (see the section "Retrieving theorems" on
  1127 page 8 of the Reference Manual);
  1128 
  1129 * new examples, including Grabczewski's monumental case study of the
  1130 Axiom of Choice;
  1131 
  1132 * The previous version of HOL renamed to Old_HOL;
  1133 
  1134 * The new version of HOL (previously called CHOL) uses a curried syntax
  1135 for functions.  Application looks like f a b instead of f(a,b);
  1136 
  1137 * Mutually recursive inductive definitions finally work in HOL;
  1138 
  1139 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1140 translates to the operator "split";
  1141 
  1142 
  1143 
  1144 New in Isabelle94-3
  1145 -------------------
  1146 
  1147 * new infix operator, addss, allowing the classical reasoner to
  1148 perform simplification at each step of its search.  Example:
  1149         fast_tac (cs addss ss)
  1150 
  1151 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1152 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1153 look like (a,b) instead of <a,b>;
  1154 
  1155 * PLEASE NOTE: CHOL will eventually replace HOL!
  1156 
  1157 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1158 It translates to the operator "split".  A new theory of integers is available;
  1159 
  1160 * In ZF, integer numerals now denote two's-complement binary integers.
  1161 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1162 
  1163 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1164 of the Axiom of Choice;
  1165 
  1166 
  1167 
  1168 New in Isabelle94-2
  1169 -------------------
  1170 
  1171 * Significantly faster resolution;
  1172 
  1173 * the different sections in a .thy file can now be mixed and repeated
  1174 freely;
  1175 
  1176 * Database of theorems for FOL, HOL and ZF.  New
  1177 commands including qed, qed_goal and bind_thm store theorems in the database.
  1178 
  1179 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1180 a given theory (thms_of), or find out what theory a theorem was proved in
  1181 (theory_of_thm);
  1182 
  1183 * Bugs fixed in the inductive definition and datatype packages;
  1184 
  1185 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1186 and HOL_dup_cs obsolete;
  1187 
  1188 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1189 have been removed;
  1190 
  1191 * Simpler definition of function space in ZF;
  1192 
  1193 * new results about cardinal and ordinal arithmetic in ZF;
  1194 
  1195 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1196 types;
  1197 
  1198 
  1199 $Id$