NEWS
author wenzelm
Sat Oct 30 20:41:30 1999 +0200 (1999-10-30)
changeset 7986 9d319a76dbeb
parent 7919 35c18affc1d8
child 8007 c29e27ee4933
permissions -rw-r--r--
Isabelle99;
     1 
     2 Isabelle NEWS -- history user-relevant changes
     3 ==============================================
     4 
     5 New in Isabelle99 (October 1999)
     6 --------------------------------
     7 
     8 *** Overview of INCOMPATIBILITIES (see below for more details) ***
     9 
    10 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
    11 are no longer simplified.  (This allows the simplifier to unfold recursive
    12 functional programs.)  To restore the old behaviour, declare
    13 
    14     Delcongs [if_weak_cong];
    15 
    16 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
    17 complement;
    18 
    19 * HOL: the predicate "inj" is now defined by translation to "inj_on";
    20 
    21 * HOL/datatype: mutual_induct_tac no longer exists --
    22   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
    23 
    24 * HOL/typedef: fixed type inference for representing set; type
    25 arguments now have to occur explicitly on the rhs as type constraints;
    26 
    27 * ZF: The con_defs part of an inductive definition may no longer refer
    28 to constants declared in the same theory;
    29 
    30 * HOL, ZF: the function mk_cases, generated by the inductive
    31 definition package, has lost an argument.  To simplify its result, it
    32 uses the default simpset instead of a supplied list of theorems.
    33 
    34 * HOL/List: the constructors of type list are now Nil and Cons;
    35 
    36 * Simplifier: the type of the infix ML functions
    37 	setSSolver addSSolver setSolver addSolver
    38 is now  simpset * solver -> simpset  where `solver' is a new abstract type
    39 for packaging solvers. A solver is created via
    40 	mk_solver: string -> (thm list -> int -> tactic) -> solver
    41 where the string argument is only a comment.
    42 
    43 
    44 *** Proof tools ***
    45 
    46 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
    47 decision procedure for linear arithmetic. Currently it is used for
    48 types `nat', `int', and `real' in HOL (see below); it can, should and
    49 will be instantiated for other types and logics as well.
    50 
    51 * The simplifier now accepts rewrite rules with flexible heads, eg
    52      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
    53   They are applied like any rule with a non-pattern lhs, i.e. by first-order
    54   matching.
    55 
    56 
    57 *** General ***
    58 
    59 * New Isabelle/Isar subsystem provides an alternative to traditional
    60 tactical theorem proving; together with the ProofGeneral/isar user
    61 interface it offers an interactive environment for developing human
    62 readable proof documents (Isar == Intelligible semi-automated
    63 reasoning); for further information see isatool doc isar-ref,
    64 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
    65 
    66 * improved presentation of theories: better HTML markup (including
    67 colors), graph views in several sizes; isatool usedir now provides a
    68 proper interface for user theories (via -P option); actual document
    69 preparation based on (PDF)LaTeX is available as well (for new-style
    70 theories only); see isatool doc system for more information;
    71 
    72 * native support for Proof General, both for classic Isabelle and
    73 Isabelle/Isar;
    74 
    75 * ML function thm_deps visualizes dependencies of theorems and lemmas,
    76 using the graph browser tool;
    77 
    78 * Isabelle manuals now also available as PDF;
    79 
    80 * theory loader rewritten from scratch (may not be fully
    81 bug-compatible); old loadpath variable has been replaced by show_path,
    82 add_path, del_path, reset_path functions; new operations such as
    83 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
    84 isatool doc ref);
    85 
    86 * improved isatool install: option -k creates KDE application icon,
    87 option -p DIR installs standalone binaries;
    88 
    89 * added ML_PLATFORM setting (useful for cross-platform installations);
    90 more robust handling of platform specific ML images for SML/NJ;
    91 
    92 * the settings environment is now statically scoped, i.e. it is never
    93 created again in sub-processes invoked from isabelle, isatool, or
    94 Isabelle;
    95 
    96 * path element specification '~~' refers to '$ISABELLE_HOME';
    97 
    98 * in locales, the "assumes" and "defines" parts may be omitted if
    99 empty;
   100 
   101 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
   102 long arrows);
   103 
   104 * new print_mode "HTML";
   105 
   106 * new flag show_tags controls display of tags of theorems (which are
   107 basically just comments that may be attached by some tools);
   108 
   109 * Isamode 2.6 requires patch to accomodate change of Isabelle font
   110 mode and goal output format:
   111 
   112 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
   113 244c244
   114 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
   115 ---
   116 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
   117 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
   118 181c181
   119 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
   120 ---
   121 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
   122 
   123 * function bind_thms stores lists of theorems (cf. bind_thm);
   124 
   125 * new shorthand tactics ftac, eatac, datac, fatac;
   126 
   127 * qed (and friends) now accept "" as result name; in that case the
   128 theorem is not stored, but proper checks and presentation of the
   129 result still apply;
   130 
   131 * theorem database now also indexes constants "Trueprop", "all",
   132 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
   133 
   134 
   135 *** HOL ***
   136 
   137 ** HOL arithmetic **
   138 
   139 * There are now decision procedures for linear arithmetic over nat and
   140 int:
   141 
   142 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
   143 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
   144 are treated as atomic; subformulae not involving type `nat' or `int'
   145 are ignored; quantified subformulae are ignored unless they are
   146 positive universal or negative existential. The tactic has to be
   147 invoked by hand and can be a little bit slow. In particular, the
   148 running time is exponential in the number of occurrences of `min' and
   149 `max', and `-' on `nat'.
   150 
   151 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
   152 (negated) (in)equalities among the premises and the conclusion into
   153 account (i.e. no compound formulae) and does not know about `min' and
   154 `max', and `-' on `nat'. It is fast and is used automatically by the
   155 simplifier.
   156 
   157 NB: At the moment, these decision procedures do not cope with mixed
   158 nat/int formulae where the two parts interact, such as `m < n ==>
   159 int(m) < int(n)'.
   160 
   161 * HOL/Numeral provides a generic theory of numerals (encoded
   162 efficiently as bit strings); setup for types nat/int/real is in place;
   163 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
   164 int, existing theories and proof scripts may require a few additional
   165 type constraints;
   166 
   167 * integer division and remainder can now be performed on constant
   168 arguments;
   169 
   170 * many properties of integer multiplication, division and remainder
   171 are now available;
   172 
   173 * An interface to the Stanford Validity Checker (SVC) is available through the
   174 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
   175 are proved automatically.  SVC must be installed separately, and its results
   176 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
   177 invocation of the underlying oracle).  For SVC see
   178   http://verify.stanford.edu/SVC
   179 
   180 * IsaMakefile: the HOL-Real target now builds an actual image;
   181 
   182 
   183 ** HOL misc **
   184 
   185 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
   186 (in Isabelle/Isar) -- by Gertrud Bauer;
   187 
   188 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
   189 analysis for assembly languages with subtypes;
   190 
   191 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
   192 -- avoids syntactic ambiguities and treats state, transition, and
   193 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
   194 changed syntax and (many) tactics;
   195 
   196 * HOL/inductive: Now also handles more general introduction rules such
   197   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
   198   theorems are now maintained within the theory (maintained via the
   199   "mono" attribute);
   200 
   201 * HOL/datatype: Now also handles arbitrarily branching datatypes
   202   (using function types) such as
   203 
   204   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
   205 
   206 * HOL/record: record_simproc (part of the default simpset) takes care
   207 of selectors applied to updated records; record_split_tac is no longer
   208 part of the default claset; update_defs may now be removed from the
   209 simpset in many cases; COMPATIBILITY: old behavior achieved by
   210 
   211   claset_ref () := claset() addSWrapper record_split_wrapper;
   212   Delsimprocs [record_simproc]
   213 
   214 * HOL/typedef: fixed type inference for representing set; type
   215 arguments now have to occur explicitly on the rhs as type constraints;
   216 
   217 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
   218 names rather than an ML expression;
   219 
   220 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
   221 supplied later.  Program schemes can be defined, such as
   222     "While B C s = (if B s then While B C (C s) else s)"
   223 where the well-founded relation can be chosen after B and C have been given.
   224 
   225 * HOL/List: the constructors of type list are now Nil and Cons;
   226 INCOMPATIBILITY: while [] and infix # syntax is still there, of
   227 course, ML tools referring to List.list.op # etc. have to be adapted;
   228 
   229 * HOL_quantifiers flag superseded by "HOL" print mode, which is
   230 disabled by default; run isabelle with option -m HOL to get back to
   231 the original Gordon/HOL-style output;
   232 
   233 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
   234 ALL x<=y. P, EX x<y. P, EX x<=y. P;
   235 
   236 * HOL basic syntax simplified (more orthogonal): all variants of
   237 All/Ex now support plain / symbolic / HOL notation; plain syntax for
   238 Eps operator is provided as well: "SOME x. P[x]";
   239 
   240 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
   241 
   242 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
   243 thus available for user theories;
   244 
   245 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
   246 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
   247 time;
   248 
   249 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
   250 several times and then mp;
   251 
   252 
   253 *** LK ***
   254 
   255 * the notation <<...>> is now available as a notation for sequences of
   256 formulas;
   257 
   258 * the simplifier is now installed
   259 
   260 * the axiom system has been generalized (thanks to Soren Heilmann) 
   261 
   262 * the classical reasoner now has a default rule database
   263 
   264 
   265 *** ZF ***
   266 
   267 * new primrec section allows primitive recursive functions to be given
   268 directly (as in HOL) over datatypes and the natural numbers;
   269 
   270 * new tactics induct_tac and exhaust_tac for induction (or case
   271 analysis) over datatypes and the natural numbers;
   272 
   273 * the datatype declaration of type T now defines the recursor T_rec;
   274 
   275 * simplification automatically does freeness reasoning for datatype
   276 constructors;
   277 
   278 * automatic type-inference, with AddTCs command to insert new
   279 type-checking rules;
   280 
   281 * datatype introduction rules are now added as Safe Introduction rules
   282 to the claset;
   283 
   284 * the syntax "if P then x else y" is now available in addition to
   285 if(P,x,y);
   286 
   287 
   288 *** Internal programming interfaces ***
   289 
   290 * tuned simplifier trace output; new flag debug_simp;
   291 
   292 * structures Vartab / Termtab (instances of TableFun) offer efficient
   293 tables indexed by indexname_ord / term_ord (compatible with aconv);
   294 
   295 * AxClass.axclass_tac lost the theory argument;
   296 
   297 * tuned current_goals_markers semantics: begin / end goal avoids
   298 printing empty lines;
   299 
   300 * removed prs and prs_fn hook, which was broken because it did not
   301 include \n in its semantics, forcing writeln to add one
   302 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
   303 string -> unit if you really want to output text without newline;
   304 
   305 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
   306 plain output, interface builders may have to enable 'isabelle_font'
   307 mode to get Isabelle font glyphs as before;
   308 
   309 * refined token_translation interface; INCOMPATIBILITY: output length
   310 now of type real instead of int;
   311 
   312 * theory loader actions may be traced via new ThyInfo.add_hook
   313 interface (see src/Pure/Thy/thy_info.ML); example application: keep
   314 your own database of information attached to *whole* theories -- as
   315 opposed to intra-theory data slots offered via TheoryDataFun;
   316 
   317 * proper handling of dangling sort hypotheses (at last!);
   318 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
   319 extra sort hypotheses that can be witnessed from the type signature;
   320 the force_strip_shyps flag is gone, any remaining shyps are simply
   321 left in the theorem (with a warning issued by strip_shyps_warning);
   322 
   323 
   324 
   325 New in Isabelle98-1 (October 1998)
   326 ----------------------------------
   327 
   328 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   329 
   330 * several changes of automated proof tools;
   331 
   332 * HOL: major changes to the inductive and datatype packages, including
   333 some minor incompatibilities of theory syntax;
   334 
   335 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
   336 called `inj_on';
   337 
   338 * HOL: removed duplicate thms in Arith:
   339   less_imp_add_less  should be replaced by  trans_less_add1
   340   le_imp_add_le      should be replaced by  trans_le_add1
   341 
   342 * HOL: unary minus is now overloaded (new type constraints may be
   343 required);
   344 
   345 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
   346 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
   347 now taken as an integer constant.
   348 
   349 * Pure: ML function 'theory_of' renamed to 'theory';
   350 
   351 
   352 *** Proof tools ***
   353 
   354 * Simplifier:
   355   1. Asm_full_simp_tac is now more aggressive.
   356      1. It will sometimes reorient premises if that increases their power to
   357         simplify.
   358      2. It does no longer proceed strictly from left to right but may also
   359         rotate premises to achieve further simplification.
   360      For compatibility reasons there is now Asm_lr_simp_tac which is like the
   361      old Asm_full_simp_tac in that it does not rotate premises.
   362   2. The simplifier now knows a little bit about nat-arithmetic.
   363 
   364 * Classical reasoner: wrapper mechanism for the classical reasoner now
   365 allows for selected deletion of wrappers, by introduction of names for
   366 wrapper functionals.  This implies that addbefore, addSbefore,
   367 addaltern, and addSaltern now take a pair (name, tactic) as argument,
   368 and that adding two tactics with the same name overwrites the first
   369 one (emitting a warning).
   370   type wrapper = (int -> tactic) -> (int -> tactic)
   371   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
   372   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
   373   delWrapper, delSWrapper: claset *  string            -> claset
   374   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
   375 
   376 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
   377 semantics; addbefore now affects only the unsafe part of step_tac
   378 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
   379 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
   380 by Force_tac;
   381 
   382 * Classical reasoner: setwrapper to setWrapper and compwrapper to
   383 compWrapper; added safe wrapper (and access functions for it);
   384 
   385 * HOL/split_all_tac is now much faster and fails if there is nothing
   386 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
   387 and the names of the automatically generated variables have changed.
   388 split_all_tac has moved within claset() from unsafe wrappers to safe
   389 wrappers, which means that !!-bound variables are split much more
   390 aggressively, and safe_tac and clarify_tac now split such variables.
   391 If this splitting is not appropriate, use delSWrapper "split_all_tac".
   392 Note: the same holds for record_split_tac, which does the job of
   393 split_all_tac for record fields.
   394 
   395 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
   396 permanently to the default simpset using Addsplits just like
   397 Addsimps. They can be removed via Delsplits just like
   398 Delsimps. Lower-case versions are also available.
   399 
   400 * HOL/Simplifier: The rule split_if is now part of the default
   401 simpset. This means that the simplifier will eliminate all occurrences
   402 of if-then-else in the conclusion of a goal. To prevent this, you can
   403 either remove split_if completely from the default simpset by
   404 `Delsplits [split_if]' or remove it in a specific call of the
   405 simplifier using `... delsplits [split_if]'.  You can also add/delete
   406 other case splitting rules to/from the default simpset: every datatype
   407 generates suitable rules `split_t_case' and `split_t_case_asm' (where
   408 t is the name of the datatype).
   409 
   410 * Classical reasoner / Simplifier combination: new force_tac (and
   411 derivatives Force_tac, force) combines rewriting and classical
   412 reasoning (and whatever other tools) similarly to auto_tac, but is
   413 aimed to solve the given subgoal completely.
   414 
   415 
   416 *** General ***
   417 
   418 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
   419 and `goalw': the theory is no longer needed as an explicit argument -
   420 the current theory context is used; assumptions are no longer returned
   421 at the ML-level unless one of them starts with ==> or !!; it is
   422 recommended to convert to these new commands using isatool fixgoal
   423 (backup your sources first!);
   424 
   425 * new top-level commands 'thm' and 'thms' for retrieving theorems from
   426 the current theory context, and 'theory' to lookup stored theories;
   427 
   428 * new theory section 'locale' for declaring constants, assumptions and
   429 definitions that have local scope;
   430 
   431 * new theory section 'nonterminals' for purely syntactic types;
   432 
   433 * new theory section 'setup' for generic ML setup functions
   434 (e.g. package initialization);
   435 
   436 * the distribution now includes Isabelle icons: see
   437 lib/logo/isabelle-{small,tiny}.xpm;
   438 
   439 * isatool install - install binaries with absolute references to
   440 ISABELLE_HOME/bin;
   441 
   442 * isatool logo -- create instances of the Isabelle logo (as EPS);
   443 
   444 * print mode 'emacs' reserved for Isamode;
   445 
   446 * support multiple print (ast) translations per constant name;
   447 
   448 * theorems involving oracles are now printed with a suffixed [!];
   449 
   450 
   451 *** HOL ***
   452 
   453 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
   454 
   455 * HOL/inductive package reorganized and improved: now supports mutual
   456 definitions such as
   457 
   458   inductive EVEN ODD
   459     intrs
   460       null "0 : EVEN"
   461       oddI "n : EVEN ==> Suc n : ODD"
   462       evenI "n : ODD ==> Suc n : EVEN"
   463 
   464 new theorem list "elims" contains an elimination rule for each of the
   465 recursive sets; inductive definitions now handle disjunctive premises
   466 correctly (also ZF);
   467 
   468 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   469 "mutual_induct" no longer exists - the induction rule is always
   470 contained in "induct";
   471 
   472 
   473 * HOL/datatype package re-implemented and greatly improved: now
   474 supports mutually recursive datatypes such as
   475 
   476   datatype
   477     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
   478             | SUM ('a aexp) ('a aexp)
   479             | DIFF ('a aexp) ('a aexp)
   480             | NUM 'a
   481   and
   482     'a bexp = LESS ('a aexp) ('a aexp)
   483             | AND ('a bexp) ('a bexp)
   484             | OR ('a bexp) ('a bexp)
   485 
   486 as well as indirectly recursive datatypes such as
   487 
   488   datatype
   489     ('a, 'b) term = Var 'a
   490                   | App 'b ((('a, 'b) term) list)
   491 
   492 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
   493 induction on mutually / indirectly recursive datatypes.
   494 
   495 Primrec equations are now stored in theory and can be accessed via
   496 <function_name>.simps.
   497 
   498 INCOMPATIBILITIES:
   499 
   500   - Theories using datatypes must now have theory Datatype as an
   501     ancestor.
   502   - The specific <typename>.induct_tac no longer exists - use the
   503     generic induct_tac instead.
   504   - natE has been renamed to nat.exhaust - use exhaust_tac
   505     instead of res_inst_tac ... natE. Note that the variable
   506     names in nat.exhaust differ from the names in natE, this
   507     may cause some "fragile" proofs to fail.
   508   - The theorems split_<typename>_case and split_<typename>_case_asm
   509     have been renamed to <typename>.split and <typename>.split_asm.
   510   - Since default sorts of type variables are now handled correctly,
   511     some datatype definitions may have to be annotated with explicit
   512     sort constraints.
   513   - Primrec definitions no longer require function name and type
   514     of recursive argument.
   515 
   516 Consider using isatool fixdatatype to adapt your theories and proof
   517 scripts to the new package (backup your sources first!).
   518 
   519 
   520 * HOL/record package: considerably improved implementation; now
   521 includes concrete syntax for record types, terms, updates; theorems
   522 for surjective pairing and splitting !!-bound record variables; proof
   523 support is as follows:
   524 
   525   1) standard conversions (selectors or updates applied to record
   526 constructor terms) are part of the standard simpset;
   527 
   528   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
   529 made part of standard simpset and claset via addIffs;
   530 
   531   3) a tactic for record field splitting (record_split_tac) is part of
   532 the standard claset (addSWrapper);
   533 
   534 To get a better idea about these rules you may retrieve them via
   535 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
   536 the name of your record type.
   537 
   538 The split tactic 3) conceptually simplifies by the following rule:
   539 
   540   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
   541 
   542 Thus any record variable that is bound by meta-all will automatically
   543 blow up into some record constructor term, consequently the
   544 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
   545 solve record problems automatically.
   546 
   547 
   548 * reorganized the main HOL image: HOL/Integ and String loaded by
   549 default; theory Main includes everything;
   550 
   551 * automatic simplification of integer sums and comparisons, using cancellation;
   552 
   553 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
   554 
   555 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
   556 
   557 * many new identities for unions, intersections, set difference, etc.;
   558 
   559 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
   560 called split_if, split_split, split_sum_case and split_nat_case (to go
   561 with add/delsplits);
   562 
   563 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
   564 (?x::unit) = (); this is made part of the default simpset, which COULD
   565 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
   566 'Delsimprocs [unit_eq_proc];' as last resort); also note that
   567 unit_abs_eta_conv is added in order to counter the effect of
   568 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
   569 %u.f();
   570 
   571 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
   572 makes more sense);
   573 
   574 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   575   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   576   disjointness reasoning but breaking a few old proofs.
   577 
   578 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
   579 to 'converse' from 'inverse' (for compatibility with ZF and some
   580 literature);
   581 
   582 * HOL/recdef can now declare non-recursive functions, with {} supplied as
   583 the well-founded relation;
   584 
   585 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
   586     Compl A.  The "Compl" syntax remains available as input syntax for this
   587     release ONLY.
   588 
   589 * HOL/Update: new theory of function updates:
   590     f(a:=b) == %x. if x=a then b else f x
   591 may also be iterated as in f(a:=b,c:=d,...);
   592 
   593 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
   594 
   595 * HOL/List:
   596   - new function list_update written xs[i:=v] that updates the i-th
   597     list position. May also be iterated as in xs[i:=a,j:=b,...].
   598   - new function `upt' written [i..j(] which generates the list
   599     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
   600     bound write [i..j], which is a shorthand for [i..j+1(].
   601   - new lexicographic orderings and corresponding wellfoundedness theorems.
   602 
   603 * HOL/Arith:
   604   - removed 'pred' (predecessor) function;
   605   - generalized some theorems about n-1;
   606   - many new laws about "div" and "mod";
   607   - new laws about greatest common divisors (see theory ex/Primes);
   608 
   609 * HOL/Relation: renamed the relational operator r^-1 "converse"
   610 instead of "inverse";
   611 
   612 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
   613   of the multiset ordering;
   614 
   615 * directory HOL/Real: a construction of the reals using Dedekind cuts
   616   (not included by default);
   617 
   618 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
   619 
   620 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
   621   programs, i.e. different program variables may have different types.
   622 
   623 * calling (stac rew i) now fails if "rew" has no effect on the goal
   624   [previously, this check worked only if the rewrite rule was unconditional]
   625   Now rew can involve either definitions or equalities (either == or =).
   626 
   627 
   628 *** ZF ***
   629 
   630 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
   631   only the theorems proved on ZF.ML;
   632 
   633 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   634   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   635   disjointness reasoning but breaking a few old proofs.
   636 
   637 * ZF/Update: new theory of function updates
   638     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
   639   may also be iterated as in f(a:=b,c:=d,...);
   640 
   641 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
   642 
   643 * calling (stac rew i) now fails if "rew" has no effect on the goal
   644   [previously, this check worked only if the rewrite rule was unconditional]
   645   Now rew can involve either definitions or equalities (either == or =).
   646 
   647 * case_tac provided for compatibility with HOL
   648     (like the old excluded_middle_tac, but with subgoals swapped)
   649 
   650 
   651 *** Internal programming interfaces ***
   652 
   653 * Pure: several new basic modules made available for general use, see
   654 also src/Pure/README;
   655 
   656 * improved the theory data mechanism to support encapsulation (data
   657 kind name replaced by private Object.kind, acting as authorization
   658 key); new type-safe user interface via functor TheoryDataFun; generic
   659 print_data function becomes basically useless;
   660 
   661 * removed global_names compatibility flag -- all theory declarations
   662 are qualified by default;
   663 
   664 * module Pure/Syntax now offers quote / antiquote translation
   665 functions (useful for Hoare logic etc. with implicit dependencies);
   666 see HOL/ex/Antiquote for an example use;
   667 
   668 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
   669 cterm -> thm;
   670 
   671 * new tactical CHANGED_GOAL for checking that a tactic modifies a
   672 subgoal;
   673 
   674 * Display.print_goals function moved to Locale.print_goals;
   675 
   676 * standard print function for goals supports current_goals_markers
   677 variable for marking begin of proof, end of proof, start of goal; the
   678 default is ("", "", ""); setting current_goals_markers := ("<proof>",
   679 "</proof>", "<goal>") causes SGML like tagged proof state printing,
   680 for example;
   681 
   682 
   683 
   684 New in Isabelle98 (January 1998)
   685 --------------------------------
   686 
   687 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   688 
   689 * changed lexical syntax of terms / types: dots made part of long
   690 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
   691 
   692 * simpset (and claset) reference variable replaced by functions
   693 simpset / simpset_ref;
   694 
   695 * no longer supports theory aliases (via merge) and non-trivial
   696 implicit merge of thms' signatures;
   697 
   698 * most internal names of constants changed due to qualified names;
   699 
   700 * changed Pure/Sequence interface (see Pure/seq.ML);
   701 
   702 
   703 *** General Changes ***
   704 
   705 * hierachically structured name spaces (for consts, types, axms, thms
   706 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
   707 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
   708 isatool fixdots ensures space after dots (e.g. "%x. x"); set
   709 long_names for fully qualified output names; NOTE: ML programs
   710 (special tactics, packages etc.) referring to internal names may have
   711 to be adapted to cope with fully qualified names; in case of severe
   712 backward campatibility problems try setting 'global_names' at compile
   713 time to have enrything declared within a flat name space; one may also
   714 fine tune name declarations in theories via the 'global' and 'local'
   715 section;
   716 
   717 * reimplemented the implicit simpset and claset using the new anytype
   718 data filed in signatures; references simpset:simpset ref etc. are
   719 replaced by functions simpset:unit->simpset and
   720 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
   721 to patch your ML files accordingly;
   722 
   723 * HTML output now includes theory graph data for display with Java
   724 applet or isatool browser; data generated automatically via isatool
   725 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
   726 
   727 * defs may now be conditional; improved rewrite_goals_tac to handle
   728 conditional equations;
   729 
   730 * defs now admits additional type arguments, using TYPE('a) syntax;
   731 
   732 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
   733 creates a new theory node; implicit merge of thms' signatures is
   734 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
   735 transfer:theory->thm->thm in (rare) cases;
   736 
   737 * improved handling of draft signatures / theories; draft thms (and
   738 ctyps, cterms) are automatically promoted to real ones;
   739 
   740 * slightly changed interfaces for oracles: admit many per theory, named
   741 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
   742 
   743 * print_goals: optional output of const types (set show_consts and
   744 show_types);
   745 
   746 * improved output of warnings (###) and errors (***);
   747 
   748 * subgoal_tac displays a warning if the new subgoal has type variables;
   749 
   750 * removed old README and Makefiles;
   751 
   752 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
   753 
   754 * removed obsolete init_pps and init_database;
   755 
   756 * deleted the obsolete tactical STATE, which was declared by
   757     fun STATE tacfun st = tacfun st st;
   758 
   759 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
   760 (which abbreviates $HOME);
   761 
   762 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
   763 use isatool fixseq to adapt your ML programs (this works for fully
   764 qualified references to the Sequence structure only!);
   765 
   766 * use_thy no longer requires writable current directory; it always
   767 reloads .ML *and* .thy file, if either one is out of date;
   768 
   769 
   770 *** Classical Reasoner ***
   771 
   772 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
   773 tactics that use classical reasoning to simplify a subgoal without
   774 splitting it into several subgoals;
   775 
   776 * Safe_tac: like safe_tac but uses the default claset;
   777 
   778 
   779 *** Simplifier ***
   780 
   781 * added simplification meta rules:
   782     (asm_)(full_)simplify: simpset -> thm -> thm;
   783 
   784 * simplifier.ML no longer part of Pure -- has to be loaded by object
   785 logics (again);
   786 
   787 * added prems argument to simplification procedures;
   788 
   789 * HOL, FOL, ZF: added infix function `addsplits':
   790   instead of `<simpset> setloop (split_tac <thms>)'
   791   you can simply write `<simpset> addsplits <thms>'
   792 
   793 
   794 *** Syntax ***
   795 
   796 * TYPE('a) syntax for type reflection terms;
   797 
   798 * no longer handles consts with name "" -- declare as 'syntax' instead;
   799 
   800 * pretty printer: changed order of mixfix annotation preference (again!);
   801 
   802 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
   803 
   804 
   805 *** HOL ***
   806 
   807 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
   808   with `addloop' of the simplifier to faciliate case splitting in premises.
   809 
   810 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
   811 
   812 * HOL/Auth: new protocol proofs including some for the Internet
   813   protocol TLS;
   814 
   815 * HOL/Map: new theory of `maps' a la VDM;
   816 
   817 * HOL/simplifier: simplification procedures nat_cancel_sums for
   818 cancelling out common nat summands from =, <, <= (in)equalities, or
   819 differences; simplification procedures nat_cancel_factor for
   820 cancelling common factor from =, <, <= (in)equalities over natural
   821 sums; nat_cancel contains both kinds of procedures, it is installed by
   822 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
   823 
   824 * HOL/simplifier: terms of the form
   825   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
   826   are rewritten to
   827   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
   828   and those of the form
   829   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
   830   are rewritten to
   831   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
   832 
   833 * HOL/datatype
   834   Each datatype `t' now comes with a theorem `split_t_case' of the form
   835 
   836   P(t_case f1 ... fn x) =
   837      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
   838         ...
   839        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
   840      )
   841 
   842   and a theorem `split_t_case_asm' of the form
   843 
   844   P(t_case f1 ... fn x) =
   845     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
   846         ...
   847        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
   848      )
   849   which can be added to a simpset via `addsplits'. The existing theorems
   850   expand_list_case and expand_option_case have been renamed to
   851   split_list_case and split_option_case.
   852 
   853 * HOL/Arithmetic:
   854   - `pred n' is automatically converted to `n-1'.
   855     Users are strongly encouraged not to use `pred' any longer,
   856     because it will disappear altogether at some point.
   857   - Users are strongly encouraged to write "0 < n" rather than
   858     "n ~= 0". Theorems and proof tools have been modified towards this
   859     `standard'.
   860 
   861 * HOL/Lists:
   862   the function "set_of_list" has been renamed "set" (and its theorems too);
   863   the function "nth" now takes its arguments in the reverse order and
   864   has acquired the infix notation "!" as in "xs!n".
   865 
   866 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
   867 
   868 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
   869   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
   870 
   871 * HOL/record: extensible records with schematic structural subtyping
   872 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
   873 still lacks various theorems and concrete record syntax;
   874 
   875 
   876 *** HOLCF ***
   877 
   878 * removed "axioms" and "generated by" sections;
   879 
   880 * replaced "ops" section by extended "consts" section, which is capable of
   881   handling the continuous function space "->" directly;
   882 
   883 * domain package:
   884   . proves theorems immediately and stores them in the theory,
   885   . creates hierachical name space,
   886   . now uses normal mixfix annotations (instead of cinfix...),
   887   . minor changes to some names and values (for consistency),
   888   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
   889   . separator between mutual domain defs: changed "," to "and",
   890   . improved handling of sort constraints;  now they have to
   891     appear on the left-hand side of the equations only;
   892 
   893 * fixed LAM <x,y,zs>.b syntax;
   894 
   895 * added extended adm_tac to simplifier in HOLCF -- can now discharge
   896 adm (%x. P (t x)), where P is chainfinite and t continuous;
   897 
   898 
   899 *** FOL and ZF ***
   900 
   901 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
   902   with `addloop' of the simplifier to faciliate case splitting in premises.
   903 
   904 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
   905 in HOL, they strip ALL and --> from proved theorems;
   906 
   907 
   908 
   909 New in Isabelle94-8 (May 1997)
   910 ------------------------------
   911 
   912 *** General Changes ***
   913 
   914 * new utilities to build / run / maintain Isabelle etc. (in parts
   915 still somewhat experimental); old Makefiles etc. still functional;
   916 
   917 * new 'Isabelle System Manual';
   918 
   919 * INSTALL text, together with ./configure and ./build scripts;
   920 
   921 * reimplemented type inference for greater efficiency, better error
   922 messages and clean internal interface;
   923 
   924 * prlim command for dealing with lots of subgoals (an easier way of
   925 setting goals_limit);
   926 
   927 
   928 *** Syntax ***
   929 
   930 * supports alternative (named) syntax tables (parser and pretty
   931 printer); internal interface is provided by add_modesyntax(_i);
   932 
   933 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
   934 be used in conjunction with the Isabelle symbol font; uses the
   935 "symbols" syntax table;
   936 
   937 * added token_translation interface (may translate name tokens in
   938 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
   939 the current print_mode); IMPORTANT: user print translation functions
   940 are responsible for marking newly introduced bounds
   941 (Syntax.mark_boundT);
   942 
   943 * token translations for modes "xterm" and "xterm_color" that display
   944 names in bold, underline etc. or colors (which requires a color
   945 version of xterm);
   946 
   947 * infixes may now be declared with names independent of their syntax;
   948 
   949 * added typed_print_translation (like print_translation, but may
   950 access type of constant);
   951 
   952 
   953 *** Classical Reasoner ***
   954 
   955 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
   956 some limitations.  Blast_tac...
   957   + ignores addss, addbefore, addafter; this restriction is intrinsic
   958   + ignores elimination rules that don't have the correct format
   959         (the conclusion MUST be a formula variable)
   960   + ignores types, which can make HOL proofs fail
   961   + rules must not require higher-order unification, e.g. apply_type in ZF
   962     [message "Function Var's argument not a bound variable" relates to this]
   963   + its proof strategy is more general but can actually be slower
   964 
   965 * substitution with equality assumptions no longer permutes other
   966 assumptions;
   967 
   968 * minor changes in semantics of addafter (now called addaltern); renamed
   969 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
   970 (and access functions for it);
   971 
   972 * improved combination of classical reasoner and simplifier:
   973   + functions for handling clasimpsets
   974   + improvement of addss: now the simplifier is called _after_ the
   975     safe steps.
   976   + safe variant of addss called addSss: uses safe simplifications
   977     _during_ the safe steps. It is more complete as it allows multiple
   978     instantiations of unknowns (e.g. with slow_tac).
   979 
   980 *** Simplifier ***
   981 
   982 * added interface for simplification procedures (functions that
   983 produce *proven* rewrite rules on the fly, depending on current
   984 redex);
   985 
   986 * ordering on terms as parameter (used for ordered rewriting);
   987 
   988 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
   989 
   990 * the solver is now split into a safe and an unsafe part.
   991 This should be invisible for the normal user, except that the
   992 functions setsolver and addsolver have been renamed to setSolver and
   993 addSolver; added safe_asm_full_simp_tac;
   994 
   995 
   996 *** HOL ***
   997 
   998 * a generic induction tactic `induct_tac' which works for all datatypes and
   999 also for type `nat';
  1000 
  1001 * a generic case distinction tactic `exhaust_tac' which works for all
  1002 datatypes and also for type `nat';
  1003 
  1004 * each datatype comes with a function `size';
  1005 
  1006 * patterns in case expressions allow tuple patterns as arguments to
  1007 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1008 
  1009 * primrec now also works with type nat;
  1010 
  1011 * recdef: a new declaration form, allows general recursive functions to be
  1012 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1013 
  1014 * the constant for negation has been renamed from "not" to "Not" to
  1015 harmonize with FOL, ZF, LK, etc.;
  1016 
  1017 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1018 infinite lists;
  1019 
  1020 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1021 
  1022 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1023 problems in commutative rings, using axiomatic type classes for + and *;
  1024 
  1025 * more examples in HOL/MiniML and HOL/Auth;
  1026 
  1027 * more default rewrite rules for quantifiers, union/intersection;
  1028 
  1029 * a new constant `arbitrary == @x.False';
  1030 
  1031 * HOLCF/IOA replaces old HOL/IOA;
  1032 
  1033 * HOLCF changes: derived all rules and arities
  1034   + axiomatic type classes instead of classes
  1035   + typedef instead of faking type definitions
  1036   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1037   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1038   + eliminated the types void, one, tr
  1039   + use unit lift and bool lift (with translations) instead of one and tr
  1040   + eliminated blift from Lift3.thy (use Def instead of blift)
  1041   all eliminated rules are derived as theorems --> no visible changes ;
  1042 
  1043 
  1044 *** ZF ***
  1045 
  1046 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1047 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1048 as ZF_cs addSIs [equalityI];
  1049 
  1050 
  1051 
  1052 New in Isabelle94-7 (November 96)
  1053 ---------------------------------
  1054 
  1055 * allowing negative levels (as offsets) in prlev and choplev;
  1056 
  1057 * super-linear speedup for large simplifications;
  1058 
  1059 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1060 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1061 FAIL); can suppress it using the command Delsimps (ex_simps @
  1062 all_simps); De Morgan laws are also now included, by default;
  1063 
  1064 * improved printing of ==>  :  ~:
  1065 
  1066 * new object-logic "Sequents" adds linear logic, while replacing LK
  1067 and Modal (thanks to Sara Kalvala);
  1068 
  1069 * HOL/Auth: correctness proofs for authentication protocols;
  1070 
  1071 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1072 examples on HOL/Auth);
  1073 
  1074 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1075 the rewriter and classical reasoner simultaneously;
  1076 
  1077 * function uresult no longer returns theorems in "standard" format;
  1078 regain previous version by: val uresult = standard o uresult;
  1079 
  1080 
  1081 
  1082 New in Isabelle94-6
  1083 -------------------
  1084 
  1085 * oracles -- these establish an interface between Isabelle and trusted
  1086 external reasoners, which may deliver results as theorems;
  1087 
  1088 * proof objects (in particular record all uses of oracles);
  1089 
  1090 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1091 
  1092 * "constdefs" section in theory files;
  1093 
  1094 * "primrec" section (HOL) no longer requires names;
  1095 
  1096 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1097 
  1098 
  1099 
  1100 New in Isabelle94-5
  1101 -------------------
  1102 
  1103 * reduced space requirements;
  1104 
  1105 * automatic HTML generation from theories;
  1106 
  1107 * theory files no longer require "..." (quotes) around most types;
  1108 
  1109 * new examples, including two proofs of the Church-Rosser theorem;
  1110 
  1111 * non-curried (1994) version of HOL is no longer distributed;
  1112 
  1113 
  1114 
  1115 New in Isabelle94-4
  1116 -------------------
  1117 
  1118 * greatly reduced space requirements;
  1119 
  1120 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1121 
  1122 * searchable theorem database (see the section "Retrieving theorems" on
  1123 page 8 of the Reference Manual);
  1124 
  1125 * new examples, including Grabczewski's monumental case study of the
  1126 Axiom of Choice;
  1127 
  1128 * The previous version of HOL renamed to Old_HOL;
  1129 
  1130 * The new version of HOL (previously called CHOL) uses a curried syntax
  1131 for functions.  Application looks like f a b instead of f(a,b);
  1132 
  1133 * Mutually recursive inductive definitions finally work in HOL;
  1134 
  1135 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1136 translates to the operator "split";
  1137 
  1138 
  1139 
  1140 New in Isabelle94-3
  1141 -------------------
  1142 
  1143 * new infix operator, addss, allowing the classical reasoner to
  1144 perform simplification at each step of its search.  Example:
  1145         fast_tac (cs addss ss)
  1146 
  1147 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1148 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1149 look like (a,b) instead of <a,b>;
  1150 
  1151 * PLEASE NOTE: CHOL will eventually replace HOL!
  1152 
  1153 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1154 It translates to the operator "split".  A new theory of integers is available;
  1155 
  1156 * In ZF, integer numerals now denote two's-complement binary integers.
  1157 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1158 
  1159 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1160 of the Axiom of Choice;
  1161 
  1162 
  1163 
  1164 New in Isabelle94-2
  1165 -------------------
  1166 
  1167 * Significantly faster resolution;
  1168 
  1169 * the different sections in a .thy file can now be mixed and repeated
  1170 freely;
  1171 
  1172 * Database of theorems for FOL, HOL and ZF.  New
  1173 commands including qed, qed_goal and bind_thm store theorems in the database.
  1174 
  1175 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1176 a given theory (thms_of), or find out what theory a theorem was proved in
  1177 (theory_of_thm);
  1178 
  1179 * Bugs fixed in the inductive definition and datatype packages;
  1180 
  1181 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1182 and HOL_dup_cs obsolete;
  1183 
  1184 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1185 have been removed;
  1186 
  1187 * Simpler definition of function space in ZF;
  1188 
  1189 * new results about cardinal and ordinal arithmetic in ZF;
  1190 
  1191 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1192 types;
  1193 
  1194 
  1195 $Id$