NEWS
author wenzelm
Wed Oct 20 11:05:06 1999 +0200 (1999-10-20)
changeset 7886 8fa551e22e52
parent 7863 8b0aca9bdc26
child 7919 35c18affc1d8
permissions -rw-r--r--
the settings environment is now statically scoped;
tuned;
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle version
     5 ----------------------------
     6 
     7 *** Overview of INCOMPATIBILITIES (see below for more details) ***
     8 
     9 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
    10 are no longer simplified.  (This allows the simplifier to unfold recursive
    11 functional programs.)  To restore the old behaviour, declare
    12 
    13     Delcongs [if_weak_cong];
    14 
    15 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
    16 complement;
    17 
    18 * HOL: the predicate "inj" is now defined by translation to "inj_on";
    19 
    20 * HOL/datatype: mutual_induct_tac no longer exists --
    21   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
    22 
    23 * HOL/typedef: fixed type inference for representing set; type
    24 arguments now have to occur explicitly on the rhs as type constraints;
    25 
    26 * ZF: The con_defs part of an inductive definition may no longer refer
    27 to constants declared in the same theory;
    28 
    29 * HOL, ZF: the function mk_cases, generated by the inductive
    30 definition package, has lost an argument.  To simplify its result, it
    31 uses the default simpset instead of a supplied list of theorems.
    32 
    33 * HOL/List: the constructors of type list are now Nil and Cons;
    34 
    35 * Simplifier: the type of the infix ML functions
    36 	setSSolver addSSolver setSolver addSolver
    37 is now  simpset * solver -> simpset  where `solver' is a new abstract type
    38 for packaging solvers. A solver is created via
    39 	mk_solver: string -> (thm list -> int -> tactic) -> solver
    40 where the string argument is only a comment.
    41 
    42 
    43 *** Proof tools ***
    44 
    45 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
    46 decision procedure for linear arithmetic. Currently it is used for
    47 types `nat', `int', and `real' in HOL (see below); it can, should and
    48 will be instantiated for other types and logics as well.
    49 
    50 * The simplifier now accepts rewrite rules with flexible heads, eg
    51      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
    52   They are applied like any rule with a non-pattern lhs, i.e. by first-order
    53   matching.
    54 
    55 
    56 *** General ***
    57 
    58 * new Isabelle/Isar subsystem provides an alternative to traditional
    59 tactical theorem proving; together with the ProofGeneral/isar user
    60 interface it offers an interactive environment for developing human
    61 readable proof documents (Isar == Intelligible semi-automated
    62 reasoning); for further information see isatool doc isar-ref,
    63 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/;
    64 
    65 * improved presentation of theories: better HTML markup (including
    66 colors), graph views in several sizes; isatool usedir now provides a
    67 proper interface for user theories (via -P option); actual document
    68 preparation based on (PDF)LaTeX is available as well (for new-style
    69 theories only); see isatool doc system for more information;
    70 
    71 * native support for Proof General, both for classic Isabelle and
    72 Isabelle/Isar (the latter is slightly better supported and more
    73 robust);
    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 read 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 result is not stored, but proper checks and presentation of the result
   129 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 several
   250   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 * structures Vartab / Termtab (instances of TableFun) offer efficient
   291 tables indexed by indexname_ord / term_ord (compatible with aconv);
   292 
   293 * AxClass.axclass_tac lost the theory argument;
   294 
   295 * tuned current_goals_markers semantics: begin / end goal avoids
   296 printing empty lines;
   297 
   298 * removed prs and prs_fn hook, which was broken because it did not
   299 include \n in its semantics, forcing writeln to add one
   300 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
   301 string -> unit if you really want to output text without newline;
   302 
   303 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
   304 plain output, interface builders may have to enable 'isabelle_font'
   305 mode to get Isabelle font glyphs as before;
   306 
   307 * refined token_translation interface; INCOMPATIBILITY: output length
   308 now of type real instead of int;
   309 
   310 * theory loader actions may be traced via new ThyInfo.add_hook
   311 interface (see src/Pure/Thy/thy_info.ML); example application: keep
   312 your own database of information attached to *whole* theories -- as
   313 opposed to intra-theory data slots offered via TheoryDataFun;
   314 
   315 * proper handling of dangling sort hypotheses (at last!);
   316 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
   317 extra sort hypotheses that can be witnessed from the type signature;
   318 the force_strip_shyps is gone, any remaining shyps are simply left in
   319 the theorem (with a warning issued by strip_shyps_warning);
   320 
   321 
   322 
   323 New in Isabelle98-1 (October 1998)
   324 ----------------------------------
   325 
   326 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   327 
   328 * several changes of automated proof tools;
   329 
   330 * HOL: major changes to the inductive and datatype packages, including
   331 some minor incompatibilities of theory syntax;
   332 
   333 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
   334 called `inj_on';
   335 
   336 * HOL: removed duplicate thms in Arith:
   337   less_imp_add_less  should be replaced by  trans_less_add1
   338   le_imp_add_le      should be replaced by  trans_le_add1
   339 
   340 * HOL: unary minus is now overloaded (new type constraints may be
   341 required);
   342 
   343 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
   344 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
   345 now taken as an integer constant.
   346 
   347 * Pure: ML function 'theory_of' renamed to 'theory';
   348 
   349 
   350 *** Proof tools ***
   351 
   352 * Simplifier:
   353   1. Asm_full_simp_tac is now more aggressive.
   354      1. It will sometimes reorient premises if that increases their power to
   355         simplify.
   356      2. It does no longer proceed strictly from left to right but may also
   357         rotate premises to achieve further simplification.
   358      For compatibility reasons there is now Asm_lr_simp_tac which is like the
   359      old Asm_full_simp_tac in that it does not rotate premises.
   360   2. The simplifier now knows a little bit about nat-arithmetic.
   361 
   362 * Classical reasoner: wrapper mechanism for the classical reasoner now
   363 allows for selected deletion of wrappers, by introduction of names for
   364 wrapper functionals.  This implies that addbefore, addSbefore,
   365 addaltern, and addSaltern now take a pair (name, tactic) as argument,
   366 and that adding two tactics with the same name overwrites the first
   367 one (emitting a warning).
   368   type wrapper = (int -> tactic) -> (int -> tactic)
   369   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
   370   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
   371   delWrapper, delSWrapper: claset *  string            -> claset
   372   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
   373 
   374 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
   375 semantics; addbefore now affects only the unsafe part of step_tac
   376 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
   377 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
   378 by Force_tac;
   379 
   380 * Classical reasoner: setwrapper to setWrapper and compwrapper to
   381 compWrapper; added safe wrapper (and access functions for it);
   382 
   383 * HOL/split_all_tac is now much faster and fails if there is nothing
   384 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
   385 and the names of the automatically generated variables have changed.
   386 split_all_tac has moved within claset() from unsafe wrappers to safe
   387 wrappers, which means that !!-bound variables are split much more
   388 aggressively, and safe_tac and clarify_tac now split such variables.
   389 If this splitting is not appropriate, use delSWrapper "split_all_tac".
   390 Note: the same holds for record_split_tac, which does the job of
   391 split_all_tac for record fields.
   392 
   393 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
   394 permanently to the default simpset using Addsplits just like
   395 Addsimps. They can be removed via Delsplits just like
   396 Delsimps. Lower-case versions are also available.
   397 
   398 * HOL/Simplifier: The rule split_if is now part of the default
   399 simpset. This means that the simplifier will eliminate all occurrences
   400 of if-then-else in the conclusion of a goal. To prevent this, you can
   401 either remove split_if completely from the default simpset by
   402 `Delsplits [split_if]' or remove it in a specific call of the
   403 simplifier using `... delsplits [split_if]'.  You can also add/delete
   404 other case splitting rules to/from the default simpset: every datatype
   405 generates suitable rules `split_t_case' and `split_t_case_asm' (where
   406 t is the name of the datatype).
   407 
   408 * Classical reasoner / Simplifier combination: new force_tac (and
   409 derivatives Force_tac, force) combines rewriting and classical
   410 reasoning (and whatever other tools) similarly to auto_tac, but is
   411 aimed to solve the given subgoal completely.
   412 
   413 
   414 *** General ***
   415 
   416 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
   417 and `goalw': the theory is no longer needed as an explicit argument -
   418 the current theory context is used; assumptions are no longer returned
   419 at the ML-level unless one of them starts with ==> or !!; it is
   420 recommended to convert to these new commands using isatool fixgoal
   421 (backup your sources first!);
   422 
   423 * new top-level commands 'thm' and 'thms' for retrieving theorems from
   424 the current theory context, and 'theory' to lookup stored theories;
   425 
   426 * new theory section 'locale' for declaring constants, assumptions and
   427 definitions that have local scope;
   428 
   429 * new theory section 'nonterminals' for purely syntactic types;
   430 
   431 * new theory section 'setup' for generic ML setup functions
   432 (e.g. package initialization);
   433 
   434 * the distribution now includes Isabelle icons: see
   435 lib/logo/isabelle-{small,tiny}.xpm;
   436 
   437 * isatool install - install binaries with absolute references to
   438 ISABELLE_HOME/bin;
   439 
   440 * isatool logo -- create instances of the Isabelle logo (as EPS);
   441 
   442 * print mode 'emacs' reserved for Isamode;
   443 
   444 * support multiple print (ast) translations per constant name;
   445 
   446 * theorems involving oracles are now printed with a suffixed [!];
   447 
   448 
   449 *** HOL ***
   450 
   451 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
   452 
   453 * HOL/inductive package reorganized and improved: now supports mutual
   454 definitions such as
   455 
   456   inductive EVEN ODD
   457     intrs
   458       null "0 : EVEN"
   459       oddI "n : EVEN ==> Suc n : ODD"
   460       evenI "n : ODD ==> Suc n : EVEN"
   461 
   462 new theorem list "elims" contains an elimination rule for each of the
   463 recursive sets; inductive definitions now handle disjunctive premises
   464 correctly (also ZF);
   465 
   466 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   467 "mutual_induct" no longer exists - the induction rule is always
   468 contained in "induct";
   469 
   470 
   471 * HOL/datatype package re-implemented and greatly improved: now
   472 supports mutually recursive datatypes such as
   473 
   474   datatype
   475     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
   476             | SUM ('a aexp) ('a aexp)
   477             | DIFF ('a aexp) ('a aexp)
   478             | NUM 'a
   479   and
   480     'a bexp = LESS ('a aexp) ('a aexp)
   481             | AND ('a bexp) ('a bexp)
   482             | OR ('a bexp) ('a bexp)
   483 
   484 as well as indirectly recursive datatypes such as
   485 
   486   datatype
   487     ('a, 'b) term = Var 'a
   488                   | App 'b ((('a, 'b) term) list)
   489 
   490 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
   491 induction on mutually / indirectly recursive datatypes.
   492 
   493 Primrec equations are now stored in theory and can be accessed via
   494 <function_name>.simps.
   495 
   496 INCOMPATIBILITIES:
   497 
   498   - Theories using datatypes must now have theory Datatype as an
   499     ancestor.
   500   - The specific <typename>.induct_tac no longer exists - use the
   501     generic induct_tac instead.
   502   - natE has been renamed to nat.exhaust - use exhaust_tac
   503     instead of res_inst_tac ... natE. Note that the variable
   504     names in nat.exhaust differ from the names in natE, this
   505     may cause some "fragile" proofs to fail.
   506   - The theorems split_<typename>_case and split_<typename>_case_asm
   507     have been renamed to <typename>.split and <typename>.split_asm.
   508   - Since default sorts of type variables are now handled correctly,
   509     some datatype definitions may have to be annotated with explicit
   510     sort constraints.
   511   - Primrec definitions no longer require function name and type
   512     of recursive argument.
   513 
   514 Consider using isatool fixdatatype to adapt your theories and proof
   515 scripts to the new package (backup your sources first!).
   516 
   517 
   518 * HOL/record package: considerably improved implementation; now
   519 includes concrete syntax for record types, terms, updates; theorems
   520 for surjective pairing and splitting !!-bound record variables; proof
   521 support is as follows:
   522 
   523   1) standard conversions (selectors or updates applied to record
   524 constructor terms) are part of the standard simpset;
   525 
   526   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
   527 made part of standard simpset and claset via addIffs;
   528 
   529   3) a tactic for record field splitting (record_split_tac) is part of
   530 the standard claset (addSWrapper);
   531 
   532 To get a better idea about these rules you may retrieve them via
   533 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
   534 the name of your record type.
   535 
   536 The split tactic 3) conceptually simplifies by the following rule:
   537 
   538   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
   539 
   540 Thus any record variable that is bound by meta-all will automatically
   541 blow up into some record constructor term, consequently the
   542 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
   543 solve record problems automatically.
   544 
   545 
   546 * reorganized the main HOL image: HOL/Integ and String loaded by
   547 default; theory Main includes everything;
   548 
   549 * automatic simplification of integer sums and comparisons, using cancellation;
   550 
   551 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
   552 
   553 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
   554 
   555 * many new identities for unions, intersections, set difference, etc.;
   556 
   557 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
   558 called split_if, split_split, split_sum_case and split_nat_case (to go
   559 with add/delsplits);
   560 
   561 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
   562 (?x::unit) = (); this is made part of the default simpset, which COULD
   563 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
   564 'Delsimprocs [unit_eq_proc];' as last resort); also note that
   565 unit_abs_eta_conv is added in order to counter the effect of
   566 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
   567 %u.f();
   568 
   569 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
   570 makes more sense);
   571 
   572 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   573   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   574   disjointness reasoning but breaking a few old proofs.
   575 
   576 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
   577 to 'converse' from 'inverse' (for compatibility with ZF and some
   578 literature);
   579 
   580 * HOL/recdef can now declare non-recursive functions, with {} supplied as
   581 the well-founded relation;
   582 
   583 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
   584     Compl A.  The "Compl" syntax remains available as input syntax for this
   585     release ONLY.
   586 
   587 * HOL/Update: new theory of function updates:
   588     f(a:=b) == %x. if x=a then b else f x
   589 may also be iterated as in f(a:=b,c:=d,...);
   590 
   591 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
   592 
   593 * HOL/List:
   594   - new function list_update written xs[i:=v] that updates the i-th
   595     list position. May also be iterated as in xs[i:=a,j:=b,...].
   596   - new function `upt' written [i..j(] which generates the list
   597     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
   598     bound write [i..j], which is a shorthand for [i..j+1(].
   599   - new lexicographic orderings and corresponding wellfoundedness theorems.
   600 
   601 * HOL/Arith:
   602   - removed 'pred' (predecessor) function;
   603   - generalized some theorems about n-1;
   604   - many new laws about "div" and "mod";
   605   - new laws about greatest common divisors (see theory ex/Primes);
   606 
   607 * HOL/Relation: renamed the relational operator r^-1 "converse"
   608 instead of "inverse";
   609 
   610 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
   611   of the multiset ordering;
   612 
   613 * directory HOL/Real: a construction of the reals using Dedekind cuts
   614   (not included by default);
   615 
   616 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
   617 
   618 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
   619   programs, i.e. different program variables may have different types.
   620 
   621 * calling (stac rew i) now fails if "rew" has no effect on the goal
   622   [previously, this check worked only if the rewrite rule was unconditional]
   623   Now rew can involve either definitions or equalities (either == or =).
   624 
   625 
   626 *** ZF ***
   627 
   628 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
   629   only the theorems proved on ZF.ML;
   630 
   631 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   632   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   633   disjointness reasoning but breaking a few old proofs.
   634 
   635 * ZF/Update: new theory of function updates
   636     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
   637   may also be iterated as in f(a:=b,c:=d,...);
   638 
   639 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
   640 
   641 * calling (stac rew i) now fails if "rew" has no effect on the goal
   642   [previously, this check worked only if the rewrite rule was unconditional]
   643   Now rew can involve either definitions or equalities (either == or =).
   644 
   645 * case_tac provided for compatibility with HOL
   646     (like the old excluded_middle_tac, but with subgoals swapped)
   647 
   648 
   649 *** Internal programming interfaces ***
   650 
   651 * Pure: several new basic modules made available for general use, see
   652 also src/Pure/README;
   653 
   654 * improved the theory data mechanism to support encapsulation (data
   655 kind name replaced by private Object.kind, acting as authorization
   656 key); new type-safe user interface via functor TheoryDataFun; generic
   657 print_data function becomes basically useless;
   658 
   659 * removed global_names compatibility flag -- all theory declarations
   660 are qualified by default;
   661 
   662 * module Pure/Syntax now offers quote / antiquote translation
   663 functions (useful for Hoare logic etc. with implicit dependencies);
   664 see HOL/ex/Antiquote for an example use;
   665 
   666 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
   667 cterm -> thm;
   668 
   669 * new tactical CHANGED_GOAL for checking that a tactic modifies a
   670 subgoal;
   671 
   672 * Display.print_goals function moved to Locale.print_goals;
   673 
   674 * standard print function for goals supports current_goals_markers
   675 variable for marking begin of proof, end of proof, start of goal; the
   676 default is ("", "", ""); setting current_goals_markers := ("<proof>",
   677 "</proof>", "<goal>") causes SGML like tagged proof state printing,
   678 for example;
   679 
   680 
   681 
   682 New in Isabelle98 (January 1998)
   683 --------------------------------
   684 
   685 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   686 
   687 * changed lexical syntax of terms / types: dots made part of long
   688 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
   689 
   690 * simpset (and claset) reference variable replaced by functions
   691 simpset / simpset_ref;
   692 
   693 * no longer supports theory aliases (via merge) and non-trivial
   694 implicit merge of thms' signatures;
   695 
   696 * most internal names of constants changed due to qualified names;
   697 
   698 * changed Pure/Sequence interface (see Pure/seq.ML);
   699 
   700 
   701 *** General Changes ***
   702 
   703 * hierachically structured name spaces (for consts, types, axms, thms
   704 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
   705 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
   706 isatool fixdots ensures space after dots (e.g. "%x. x"); set
   707 long_names for fully qualified output names; NOTE: ML programs
   708 (special tactics, packages etc.) referring to internal names may have
   709 to be adapted to cope with fully qualified names; in case of severe
   710 backward campatibility problems try setting 'global_names' at compile
   711 time to have enrything declared within a flat name space; one may also
   712 fine tune name declarations in theories via the 'global' and 'local'
   713 section;
   714 
   715 * reimplemented the implicit simpset and claset using the new anytype
   716 data filed in signatures; references simpset:simpset ref etc. are
   717 replaced by functions simpset:unit->simpset and
   718 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
   719 to patch your ML files accordingly;
   720 
   721 * HTML output now includes theory graph data for display with Java
   722 applet or isatool browser; data generated automatically via isatool
   723 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
   724 
   725 * defs may now be conditional; improved rewrite_goals_tac to handle
   726 conditional equations;
   727 
   728 * defs now admits additional type arguments, using TYPE('a) syntax;
   729 
   730 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
   731 creates a new theory node; implicit merge of thms' signatures is
   732 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
   733 transfer:theory->thm->thm in (rare) cases;
   734 
   735 * improved handling of draft signatures / theories; draft thms (and
   736 ctyps, cterms) are automatically promoted to real ones;
   737 
   738 * slightly changed interfaces for oracles: admit many per theory, named
   739 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
   740 
   741 * print_goals: optional output of const types (set show_consts and
   742 show_types);
   743 
   744 * improved output of warnings (###) and errors (***);
   745 
   746 * subgoal_tac displays a warning if the new subgoal has type variables;
   747 
   748 * removed old README and Makefiles;
   749 
   750 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
   751 
   752 * removed obsolete init_pps and init_database;
   753 
   754 * deleted the obsolete tactical STATE, which was declared by
   755     fun STATE tacfun st = tacfun st st;
   756 
   757 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
   758 (which abbreviates $HOME);
   759 
   760 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
   761 use isatool fixseq to adapt your ML programs (this works for fully
   762 qualified references to the Sequence structure only!);
   763 
   764 * use_thy no longer requires writable current directory; it always
   765 reloads .ML *and* .thy file, if either one is out of date;
   766 
   767 
   768 *** Classical Reasoner ***
   769 
   770 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
   771 tactics that use classical reasoning to simplify a subgoal without
   772 splitting it into several subgoals;
   773 
   774 * Safe_tac: like safe_tac but uses the default claset;
   775 
   776 
   777 *** Simplifier ***
   778 
   779 * added simplification meta rules:
   780     (asm_)(full_)simplify: simpset -> thm -> thm;
   781 
   782 * simplifier.ML no longer part of Pure -- has to be loaded by object
   783 logics (again);
   784 
   785 * added prems argument to simplification procedures;
   786 
   787 * HOL, FOL, ZF: added infix function `addsplits':
   788   instead of `<simpset> setloop (split_tac <thms>)'
   789   you can simply write `<simpset> addsplits <thms>'
   790 
   791 
   792 *** Syntax ***
   793 
   794 * TYPE('a) syntax for type reflection terms;
   795 
   796 * no longer handles consts with name "" -- declare as 'syntax' instead;
   797 
   798 * pretty printer: changed order of mixfix annotation preference (again!);
   799 
   800 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
   801 
   802 
   803 *** HOL ***
   804 
   805 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
   806   with `addloop' of the simplifier to faciliate case splitting in premises.
   807 
   808 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
   809 
   810 * HOL/Auth: new protocol proofs including some for the Internet
   811   protocol TLS;
   812 
   813 * HOL/Map: new theory of `maps' a la VDM;
   814 
   815 * HOL/simplifier: simplification procedures nat_cancel_sums for
   816 cancelling out common nat summands from =, <, <= (in)equalities, or
   817 differences; simplification procedures nat_cancel_factor for
   818 cancelling common factor from =, <, <= (in)equalities over natural
   819 sums; nat_cancel contains both kinds of procedures, it is installed by
   820 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
   821 
   822 * HOL/simplifier: terms of the form
   823   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
   824   are rewritten to
   825   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
   826   and those of the form
   827   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
   828   are rewritten to
   829   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
   830 
   831 * HOL/datatype
   832   Each datatype `t' now comes with a theorem `split_t_case' of the form
   833 
   834   P(t_case f1 ... fn x) =
   835      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
   836         ...
   837        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
   838      )
   839 
   840   and a theorem `split_t_case_asm' of the form
   841 
   842   P(t_case f1 ... fn x) =
   843     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
   844         ...
   845        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
   846      )
   847   which can be added to a simpset via `addsplits'. The existing theorems
   848   expand_list_case and expand_option_case have been renamed to
   849   split_list_case and split_option_case.
   850 
   851 * HOL/Arithmetic:
   852   - `pred n' is automatically converted to `n-1'.
   853     Users are strongly encouraged not to use `pred' any longer,
   854     because it will disappear altogether at some point.
   855   - Users are strongly encouraged to write "0 < n" rather than
   856     "n ~= 0". Theorems and proof tools have been modified towards this
   857     `standard'.
   858 
   859 * HOL/Lists:
   860   the function "set_of_list" has been renamed "set" (and its theorems too);
   861   the function "nth" now takes its arguments in the reverse order and
   862   has acquired the infix notation "!" as in "xs!n".
   863 
   864 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
   865 
   866 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
   867   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
   868 
   869 * HOL/record: extensible records with schematic structural subtyping
   870 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
   871 still lacks various theorems and concrete record syntax;
   872 
   873 
   874 *** HOLCF ***
   875 
   876 * removed "axioms" and "generated by" sections;
   877 
   878 * replaced "ops" section by extended "consts" section, which is capable of
   879   handling the continuous function space "->" directly;
   880 
   881 * domain package:
   882   . proves theorems immediately and stores them in the theory,
   883   . creates hierachical name space,
   884   . now uses normal mixfix annotations (instead of cinfix...),
   885   . minor changes to some names and values (for consistency),
   886   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
   887   . separator between mutual domain defs: changed "," to "and",
   888   . improved handling of sort constraints;  now they have to
   889     appear on the left-hand side of the equations only;
   890 
   891 * fixed LAM <x,y,zs>.b syntax;
   892 
   893 * added extended adm_tac to simplifier in HOLCF -- can now discharge
   894 adm (%x. P (t x)), where P is chainfinite and t continuous;
   895 
   896 
   897 *** FOL and ZF ***
   898 
   899 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
   900   with `addloop' of the simplifier to faciliate case splitting in premises.
   901 
   902 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
   903 in HOL, they strip ALL and --> from proved theorems;
   904 
   905 
   906 
   907 New in Isabelle94-8 (May 1997)
   908 ------------------------------
   909 
   910 *** General Changes ***
   911 
   912 * new utilities to build / run / maintain Isabelle etc. (in parts
   913 still somewhat experimental); old Makefiles etc. still functional;
   914 
   915 * new 'Isabelle System Manual';
   916 
   917 * INSTALL text, together with ./configure and ./build scripts;
   918 
   919 * reimplemented type inference for greater efficiency, better error
   920 messages and clean internal interface;
   921 
   922 * prlim command for dealing with lots of subgoals (an easier way of
   923 setting goals_limit);
   924 
   925 
   926 *** Syntax ***
   927 
   928 * supports alternative (named) syntax tables (parser and pretty
   929 printer); internal interface is provided by add_modesyntax(_i);
   930 
   931 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
   932 be used in conjunction with the Isabelle symbol font; uses the
   933 "symbols" syntax table;
   934 
   935 * added token_translation interface (may translate name tokens in
   936 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
   937 the current print_mode); IMPORTANT: user print translation functions
   938 are responsible for marking newly introduced bounds
   939 (Syntax.mark_boundT);
   940 
   941 * token translations for modes "xterm" and "xterm_color" that display
   942 names in bold, underline etc. or colors (which requires a color
   943 version of xterm);
   944 
   945 * infixes may now be declared with names independent of their syntax;
   946 
   947 * added typed_print_translation (like print_translation, but may
   948 access type of constant);
   949 
   950 
   951 *** Classical Reasoner ***
   952 
   953 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
   954 some limitations.  Blast_tac...
   955   + ignores addss, addbefore, addafter; this restriction is intrinsic
   956   + ignores elimination rules that don't have the correct format
   957         (the conclusion MUST be a formula variable)
   958   + ignores types, which can make HOL proofs fail
   959   + rules must not require higher-order unification, e.g. apply_type in ZF
   960     [message "Function Var's argument not a bound variable" relates to this]
   961   + its proof strategy is more general but can actually be slower
   962 
   963 * substitution with equality assumptions no longer permutes other
   964 assumptions;
   965 
   966 * minor changes in semantics of addafter (now called addaltern); renamed
   967 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
   968 (and access functions for it);
   969 
   970 * improved combination of classical reasoner and simplifier:
   971   + functions for handling clasimpsets
   972   + improvement of addss: now the simplifier is called _after_ the
   973     safe steps.
   974   + safe variant of addss called addSss: uses safe simplifications
   975     _during_ the safe steps. It is more complete as it allows multiple
   976     instantiations of unknowns (e.g. with slow_tac).
   977 
   978 *** Simplifier ***
   979 
   980 * added interface for simplification procedures (functions that
   981 produce *proven* rewrite rules on the fly, depending on current
   982 redex);
   983 
   984 * ordering on terms as parameter (used for ordered rewriting);
   985 
   986 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
   987 
   988 * the solver is now split into a safe and an unsafe part.
   989 This should be invisible for the normal user, except that the
   990 functions setsolver and addsolver have been renamed to setSolver and
   991 addSolver; added safe_asm_full_simp_tac;
   992 
   993 
   994 *** HOL ***
   995 
   996 * a generic induction tactic `induct_tac' which works for all datatypes and
   997 also for type `nat';
   998 
   999 * a generic case distinction tactic `exhaust_tac' which works for all
  1000 datatypes and also for type `nat';
  1001 
  1002 * each datatype comes with a function `size';
  1003 
  1004 * patterns in case expressions allow tuple patterns as arguments to
  1005 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  1006 
  1007 * primrec now also works with type nat;
  1008 
  1009 * recdef: a new declaration form, allows general recursive functions to be
  1010 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  1011 
  1012 * the constant for negation has been renamed from "not" to "Not" to
  1013 harmonize with FOL, ZF, LK, etc.;
  1014 
  1015 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  1016 infinite lists;
  1017 
  1018 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  1019 
  1020 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  1021 problems in commutative rings, using axiomatic type classes for + and *;
  1022 
  1023 * more examples in HOL/MiniML and HOL/Auth;
  1024 
  1025 * more default rewrite rules for quantifiers, union/intersection;
  1026 
  1027 * a new constant `arbitrary == @x.False';
  1028 
  1029 * HOLCF/IOA replaces old HOL/IOA;
  1030 
  1031 * HOLCF changes: derived all rules and arities
  1032   + axiomatic type classes instead of classes
  1033   + typedef instead of faking type definitions
  1034   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  1035   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  1036   + eliminated the types void, one, tr
  1037   + use unit lift and bool lift (with translations) instead of one and tr
  1038   + eliminated blift from Lift3.thy (use Def instead of blift)
  1039   all eliminated rules are derived as theorems --> no visible changes ;
  1040 
  1041 
  1042 *** ZF ***
  1043 
  1044 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  1045 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  1046 as ZF_cs addSIs [equalityI];
  1047 
  1048 
  1049 
  1050 New in Isabelle94-7 (November 96)
  1051 ---------------------------------
  1052 
  1053 * allowing negative levels (as offsets) in prlev and choplev;
  1054 
  1055 * super-linear speedup for large simplifications;
  1056 
  1057 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  1058 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  1059 FAIL); can suppress it using the command Delsimps (ex_simps @
  1060 all_simps); De Morgan laws are also now included, by default;
  1061 
  1062 * improved printing of ==>  :  ~:
  1063 
  1064 * new object-logic "Sequents" adds linear logic, while replacing LK
  1065 and Modal (thanks to Sara Kalvala);
  1066 
  1067 * HOL/Auth: correctness proofs for authentication protocols;
  1068 
  1069 * HOL: new auto_tac combines rewriting and classical reasoning (many
  1070 examples on HOL/Auth);
  1071 
  1072 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  1073 the rewriter and classical reasoner simultaneously;
  1074 
  1075 * function uresult no longer returns theorems in "standard" format;
  1076 regain previous version by: val uresult = standard o uresult;
  1077 
  1078 
  1079 
  1080 New in Isabelle94-6
  1081 -------------------
  1082 
  1083 * oracles -- these establish an interface between Isabelle and trusted
  1084 external reasoners, which may deliver results as theorems;
  1085 
  1086 * proof objects (in particular record all uses of oracles);
  1087 
  1088 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  1089 
  1090 * "constdefs" section in theory files;
  1091 
  1092 * "primrec" section (HOL) no longer requires names;
  1093 
  1094 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  1095 
  1096 
  1097 
  1098 New in Isabelle94-5
  1099 -------------------
  1100 
  1101 * reduced space requirements;
  1102 
  1103 * automatic HTML generation from theories;
  1104 
  1105 * theory files no longer require "..." (quotes) around most types;
  1106 
  1107 * new examples, including two proofs of the Church-Rosser theorem;
  1108 
  1109 * non-curried (1994) version of HOL is no longer distributed;
  1110 
  1111 
  1112 
  1113 New in Isabelle94-4
  1114 -------------------
  1115 
  1116 * greatly reduced space requirements;
  1117 
  1118 * theory files (.thy) no longer require \...\ escapes at line breaks;
  1119 
  1120 * searchable theorem database (see the section "Retrieving theorems" on
  1121 page 8 of the Reference Manual);
  1122 
  1123 * new examples, including Grabczewski's monumental case study of the
  1124 Axiom of Choice;
  1125 
  1126 * The previous version of HOL renamed to Old_HOL;
  1127 
  1128 * The new version of HOL (previously called CHOL) uses a curried syntax
  1129 for functions.  Application looks like f a b instead of f(a,b);
  1130 
  1131 * Mutually recursive inductive definitions finally work in HOL;
  1132 
  1133 * In ZF, pattern-matching on tuples is now available in all abstractions and
  1134 translates to the operator "split";
  1135 
  1136 
  1137 
  1138 New in Isabelle94-3
  1139 -------------------
  1140 
  1141 * new infix operator, addss, allowing the classical reasoner to
  1142 perform simplification at each step of its search.  Example:
  1143         fast_tac (cs addss ss)
  1144 
  1145 * a new logic, CHOL, the same as HOL, but with a curried syntax
  1146 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  1147 look like (a,b) instead of <a,b>;
  1148 
  1149 * PLEASE NOTE: CHOL will eventually replace HOL!
  1150 
  1151 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  1152 It translates to the operator "split".  A new theory of integers is available;
  1153 
  1154 * In ZF, integer numerals now denote two's-complement binary integers.
  1155 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  1156 
  1157 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  1158 of the Axiom of Choice;
  1159 
  1160 
  1161 
  1162 New in Isabelle94-2
  1163 -------------------
  1164 
  1165 * Significantly faster resolution;
  1166 
  1167 * the different sections in a .thy file can now be mixed and repeated
  1168 freely;
  1169 
  1170 * Database of theorems for FOL, HOL and ZF.  New
  1171 commands including qed, qed_goal and bind_thm store theorems in the database.
  1172 
  1173 * Simple database queries: return a named theorem (get_thm) or all theorems of
  1174 a given theory (thms_of), or find out what theory a theorem was proved in
  1175 (theory_of_thm);
  1176 
  1177 * Bugs fixed in the inductive definition and datatype packages;
  1178 
  1179 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  1180 and HOL_dup_cs obsolete;
  1181 
  1182 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  1183 have been removed;
  1184 
  1185 * Simpler definition of function space in ZF;
  1186 
  1187 * new results about cardinal and ordinal arithmetic in ZF;
  1188 
  1189 * 'subtype' facility in HOL for introducing new types as subsets of existing
  1190 types;
  1191 
  1192 
  1193 $Id$