NEWS
author paulson
Wed Jul 01 17:59:25 1998 +0200 (1998-07-01)
changeset 5106 05b7c9a2ddf9
parent 5085 8e5a7942fdea
child 5109 b3d18eb3ac20
permissions -rw-r--r--
HOL-Real
     1 Isabelle NEWS -- history of user-visible changes
     2 ================================================
     3 
     4 New in this Isabelle version
     5 ----------------------------
     6 
     7 *** General Changes ***
     8 
     9 * new toplevel commands `Goal' and `Goalw' that improve upon `goal'
    10 and `goalw': the theory is no longer needed as an explicit argument -
    11 the current theory is used; assumptions are no longer returned at the
    12 ML-level unless one of them starts with ==> or !!; it is recommended
    13 to convert to these new commands using isatool fixgoal (as usual,
    14 backup your sources first!);
    15 
    16 * Simplifier: Asm_full_simp_tac is now more aggressive.
    17   1. It will sometimes reorient premises if that increases their power to
    18      simplify.
    19   2. It does no longer proceed strictly from left to right but may also
    20      rotate premises to achieve further simplification.
    21   For compatibility reasons there is now Asm_lr_simp_tac which is like the
    22   old Asm_full_simp_tac in that it does not rotate premises.
    23 
    24 * Changed wrapper mechanism for the classical reasoner now allows for
    25 selected deletion of wrappers, by introduction of names for wrapper
    26 functionals.  This implies that addbefore, addSbefore, addaltern, and
    27 addSaltern now take a pair (name, tactic) as argument, and that adding
    28 two tactics with the same name overwrites the first one (emitting a
    29 warning).
    30   type wrapper = (int -> tactic) -> (int -> tactic)
    31   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
    32   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
    33   delWrapper, delSWrapper: claset *  string            -> claset
    34   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
    35 
    36 * inductive definitions now handle disjunctive premises correctly (HOL
    37 and ZF);
    38 
    39 * new toplevel commands 'thm' and 'thms' for retrieving theorems from
    40 the current theory context;
    41 
    42 * new theory section 'nonterminals';
    43 
    44 * new theory section 'setup';
    45 
    46 
    47 *** HOL ***
    48 
    49 * HOL/Real: a construction of the reals using Dedekind cuts
    50 
    51 * HOL/record: now includes concrete syntax for record terms (still
    52 lacks important theorems, like surjective pairing and split);
    53 
    54 * simplification procedure unit_eq_proc rewrites (?x::unit) = (); this
    55 is made part of the default simpset of Prod.thy, which COULD MAKE
    56 EXISTING PROOFS FAIL (consider 'Delsimprocs [unit_eq_proc];' as last
    57 resort);
    58 
    59 * new force_tac (and its derivations Force_tac, force): combines
    60 rewriting and classical reasoning (and whatever other tools) similarly
    61 to auto_tac, but is aimed to solve the given subgoal totally;
    62 
    63 * added option_map_eq_Some to simpset() and claset()
    64 
    65 * New directory HOL/UNITY: Chandy and Misra's UNITY formalism
    66 
    67 * New theory HOL/Update of function updates:
    68   f(a:=b) == %x. if x=a then b else f x
    69   May also be iterated as in f(a:=b,c:=d,...).
    70 
    71 * HOL/List: new function list_update written xs[i:=v] that updates the i-th
    72   list position. May also be iterated as in xs[i:=a,j:=b,...].
    73 
    74 * split_all_tac is now much faster and fails if there is nothing to
    75 split.  Existing (fragile) proofs may require adaption because the
    76 order and the names of the automatically generated variables have
    77 changed.  split_all_tac has moved within claset() from usafe wrappers
    78 to safe wrappers, which means that !!-bound variables are splitted
    79 much more aggressively, and safe_tac and clarify_tac now split such
    80 variables.  If this splitting is not appropriate, use delSWrapper
    81 "split_all_tac".
    82 
    83 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
    84 
    85 * HOL/Arithmetic:
    86   
    87   - removed 'pred' (predecessor) function
    88   - generalized some theorems about n-1
    89   - Many new laws about "div" and "mod"
    90   - New laws about greatest common divisors (see theory ex/Primes)
    91 
    92 * HOL/Relation: renamed the relational operatotr r^-1 "converse"
    93 instead of "inverse";
    94 
    95 * recdef can now declare non-recursive functions, with {} supplied as
    96 the well-founded relation;
    97 
    98 * expand_if, expand_split, expand_sum_case and expand_nat_case are now called
    99   split_if, split_split, split_sum_case and split_nat_case
   100   (to go with add/delsplits).
   101 
   102 * Simplifier:
   103 
   104  -Rewrite rules for case distinctions can now be added permanently to the
   105   default simpset using Addsplits just like Addsimps. They can be removed via
   106   Delsplits just like Delsimps. Lower-case versions are also available.
   107 
   108  -The rule split_if is now part of the default simpset. This means that
   109   the simplifier will eliminate all ocurrences of if-then-else in the
   110   conclusion of a goal. To prevent this, you can either remove split_if
   111   completely from the default simpset by `Delsplits [split_if]' or
   112   remove it in a specific call of the simplifier using
   113   `... delsplits [split_if]'.
   114   You can also add/delete other case splitting rules to/from the default
   115   simpset: every datatype generates suitable rules `split_t_case' and
   116   `split_t_case_asm' (where t is the name of the datatype).
   117 
   118 * new theory Vimage (inverse image of a function, syntax f-``B);
   119 
   120 * many new identities for unions, intersections, set difference, etc.;
   121 
   122 
   123 *** ZF ***
   124 
   125 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
   126 
   127 
   128 *** Internal changes ***
   129 
   130 * improved the theory data mechanism to support encapsulation (data
   131 kind name replaced by private Object.kind, acting as authorization
   132 key); new type-safe user interface via functor TheoryDataFun;
   133 
   134 * module Pure/Syntax now offers quote / antiquote translation
   135 functions (useful for Hoare logic etc. with implicit dependencies);
   136 
   137 
   138 
   139 New in Isabelle98 (January 1998)
   140 --------------------------------
   141 
   142 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   143 
   144 * changed lexical syntax of terms / types: dots made part of long
   145 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
   146 
   147 * simpset (and claset) reference variable replaced by functions
   148 simpset / simpset_ref;
   149 
   150 * no longer supports theory aliases (via merge) and non-trivial
   151 implicit merge of thms' signatures;
   152 
   153 * most internal names of constants changed due to qualified names;
   154 
   155 * changed Pure/Sequence interface (see Pure/seq.ML);
   156 
   157 
   158 *** General Changes ***
   159 
   160 * hierachically structured name spaces (for consts, types, axms, thms
   161 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
   162 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
   163 isatool fixdots ensures space after dots (e.g. "%x. x"); set
   164 long_names for fully qualified output names; NOTE: ML programs
   165 (special tactics, packages etc.) referring to internal names may have
   166 to be adapted to cope with fully qualified names; in case of severe
   167 backward campatibility problems try setting 'global_names' at compile
   168 time to have enrything declared within a flat name space; one may also
   169 fine tune name declarations in theories via the 'global' and 'local'
   170 section;
   171 
   172 * reimplemented the implicit simpset and claset using the new anytype
   173 data filed in signatures; references simpset:simpset ref etc. are
   174 replaced by functions simpset:unit->simpset and
   175 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
   176 to patch your ML files accordingly;
   177 
   178 * HTML output now includes theory graph data for display with Java
   179 applet or isatool browser; data generated automatically via isatool
   180 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
   181 
   182 * defs may now be conditional; improved rewrite_goals_tac to handle
   183 conditional equations;
   184 
   185 * defs now admits additional type arguments, using TYPE('a) syntax;
   186 
   187 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
   188 creates a new theory node; implicit merge of thms' signatures is
   189 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
   190 transfer:theory->thm->thm in (rare) cases;
   191 
   192 * improved handling of draft signatures / theories; draft thms (and
   193 ctyps, cterms) are automatically promoted to real ones;
   194 
   195 * slightly changed interfaces for oracles: admit many per theory, named
   196 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
   197 
   198 * print_goals: optional output of const types (set show_consts and
   199 show_types);
   200 
   201 * improved output of warnings (###) and errors (***);
   202 
   203 * subgoal_tac displays a warning if the new subgoal has type variables;
   204 
   205 * removed old README and Makefiles;
   206 
   207 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
   208 
   209 * removed obsolete init_pps and init_database;
   210 
   211 * deleted the obsolete tactical STATE, which was declared by
   212     fun STATE tacfun st = tacfun st st;
   213 
   214 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
   215 (which abbreviates $HOME);
   216 
   217 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
   218 use isatool fixseq to adapt your ML programs (this works for fully
   219 qualified references to the Sequence structure only!);
   220 
   221 * use_thy no longer requires writable current directory; it always
   222 reloads .ML *and* .thy file, if either one is out of date;
   223 
   224 
   225 *** Classical Reasoner ***
   226 
   227 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
   228 tactics that use classical reasoning to simplify a subgoal without
   229 splitting it into several subgoals;
   230 
   231 * Safe_tac: like safe_tac but uses the default claset;
   232 
   233 
   234 *** Simplifier ***
   235 
   236 * added simplification meta rules:
   237     (asm_)(full_)simplify: simpset -> thm -> thm;
   238 
   239 * simplifier.ML no longer part of Pure -- has to be loaded by object
   240 logics (again);
   241 
   242 * added prems argument to simplification procedures;
   243 
   244 * HOL, FOL, ZF: added infix function `addsplits':
   245   instead of `<simpset> setloop (split_tac <thms>)'
   246   you can simply write `<simpset> addsplits <thms>'
   247 
   248 
   249 *** Syntax ***
   250 
   251 * TYPE('a) syntax for type reflection terms;
   252 
   253 * no longer handles consts with name "" -- declare as 'syntax' instead;
   254 
   255 * pretty printer: changed order of mixfix annotation preference (again!);
   256 
   257 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
   258 
   259 
   260 *** HOL ***
   261 
   262 * HOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   263   with `addloop' of the simplifier to faciliate case splitting in premises.
   264 
   265 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
   266 
   267 * HOL/Auth: new protocol proofs including some for the Internet
   268   protocol TLS;
   269 
   270 * HOL/Map: new theory of `maps' a la VDM;
   271 
   272 * HOL/simplifier: simplification procedures nat_cancel_sums for
   273 cancelling out common nat summands from =, <, <= (in)equalities, or
   274 differences; simplification procedures nat_cancel_factor for
   275 cancelling common factor from =, <, <= (in)equalities over natural
   276 sums; nat_cancel contains both kinds of procedures, it is installed by
   277 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
   278 
   279 * HOL/simplifier: terms of the form
   280   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
   281   are rewritten to
   282   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
   283   and those of the form
   284   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
   285   are rewritten to
   286   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
   287 
   288 * HOL/datatype
   289   Each datatype `t' now comes with a theorem `split_t_case' of the form
   290 
   291   P(t_case f1 ... fn x) =
   292      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
   293         ...
   294        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
   295      )
   296 
   297   and a theorem `split_t_case_asm' of the form
   298 
   299   P(t_case f1 ... fn x) =
   300     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
   301         ...
   302        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
   303      )
   304   which can be added to a simpset via `addsplits'. The existing theorems
   305   expand_list_case and expand_option_case have been renamed to
   306   split_list_case and split_option_case.
   307 
   308 * HOL/Arithmetic:
   309   - `pred n' is automatically converted to `n-1'.
   310     Users are strongly encouraged not to use `pred' any longer,
   311     because it will disappear altogether at some point.
   312   - Users are strongly encouraged to write "0 < n" rather than
   313     "n ~= 0". Theorems and proof tools have been modified towards this
   314     `standard'.
   315 
   316 * HOL/Lists:
   317   the function "set_of_list" has been renamed "set" (and its theorems too);
   318   the function "nth" now takes its arguments in the reverse order and
   319   has acquired the infix notation "!" as in "xs!n".
   320 
   321 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
   322 
   323 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
   324   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
   325 
   326 * HOL/record: extensible records with schematic structural subtyping
   327 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
   328 still lacks various theorems and concrete record syntax;
   329 
   330 
   331 *** HOLCF ***
   332 
   333 * removed "axioms" and "generated by" sections;
   334 
   335 * replaced "ops" section by extended "consts" section, which is capable of
   336   handling the continuous function space "->" directly;
   337 
   338 * domain package:
   339   . proves theorems immediately and stores them in the theory,
   340   . creates hierachical name space,
   341   . now uses normal mixfix annotations (instead of cinfix...),
   342   . minor changes to some names and values (for consistency),
   343   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
   344   . separator between mutual domain defs: changed "," to "and",
   345   . improved handling of sort constraints;  now they have to
   346     appear on the left-hand side of the equations only;
   347 
   348 * fixed LAM <x,y,zs>.b syntax;
   349 
   350 * added extended adm_tac to simplifier in HOLCF -- can now discharge
   351 adm (%x. P (t x)), where P is chainfinite and t continuous;
   352 
   353 
   354 *** FOL and ZF ***
   355 
   356 * FOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   357   with `addloop' of the simplifier to faciliate case splitting in premises.
   358 
   359 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
   360 in HOL, they strip ALL and --> from proved theorems;
   361 
   362 
   363 
   364 New in Isabelle94-8 (May 1997)
   365 ------------------------------
   366 
   367 *** General Changes ***
   368 
   369 * new utilities to build / run / maintain Isabelle etc. (in parts
   370 still somewhat experimental); old Makefiles etc. still functional;
   371 
   372 * new 'Isabelle System Manual';
   373 
   374 * INSTALL text, together with ./configure and ./build scripts;
   375 
   376 * reimplemented type inference for greater efficiency, better error
   377 messages and clean internal interface;
   378 
   379 * prlim command for dealing with lots of subgoals (an easier way of
   380 setting goals_limit);
   381 
   382 
   383 *** Syntax ***
   384 
   385 * supports alternative (named) syntax tables (parser and pretty
   386 printer); internal interface is provided by add_modesyntax(_i);
   387 
   388 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
   389 be used in conjunction with the Isabelle symbol font; uses the
   390 "symbols" syntax table;
   391 
   392 * added token_translation interface (may translate name tokens in
   393 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
   394 the current print_mode); IMPORTANT: user print translation functions
   395 are responsible for marking newly introduced bounds
   396 (Syntax.mark_boundT);
   397 
   398 * token translations for modes "xterm" and "xterm_color" that display
   399 names in bold, underline etc. or colors (which requires a color
   400 version of xterm);
   401 
   402 * infixes may now be declared with names independent of their syntax;
   403 
   404 * added typed_print_translation (like print_translation, but may
   405 access type of constant);
   406 
   407 
   408 *** Classical Reasoner ***
   409 
   410 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
   411 some limitations.  Blast_tac...
   412   + ignores addss, addbefore, addafter; this restriction is intrinsic
   413   + ignores elimination rules that don't have the correct format
   414 	(the conclusion MUST be a formula variable)
   415   + ignores types, which can make HOL proofs fail
   416   + rules must not require higher-order unification, e.g. apply_type in ZF
   417     [message "Function Var's argument not a bound variable" relates to this]
   418   + its proof strategy is more general but can actually be slower
   419 
   420 * substitution with equality assumptions no longer permutes other
   421 assumptions;
   422 
   423 * minor changes in semantics of addafter (now called addaltern); renamed
   424 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
   425 (and access functions for it);
   426 
   427 * improved combination of classical reasoner and simplifier: 
   428   + functions for handling clasimpsets
   429   + improvement of addss: now the simplifier is called _after_ the
   430     safe steps.
   431   + safe variant of addss called addSss: uses safe simplifications
   432     _during_ the safe steps. It is more complete as it allows multiple 
   433     instantiations of unknowns (e.g. with slow_tac).
   434 
   435 *** Simplifier ***
   436 
   437 * added interface for simplification procedures (functions that
   438 produce *proven* rewrite rules on the fly, depending on current
   439 redex);
   440 
   441 * ordering on terms as parameter (used for ordered rewriting);
   442 
   443 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
   444 
   445 * the solver is now split into a safe and an unsafe part.
   446 This should be invisible for the normal user, except that the
   447 functions setsolver and addsolver have been renamed to setSolver and
   448 addSolver; added safe_asm_full_simp_tac;
   449 
   450 
   451 *** HOL ***
   452 
   453 * a generic induction tactic `induct_tac' which works for all datatypes and
   454 also for type `nat';
   455 
   456 * a generic case distinction tactic `exhaust_tac' which works for all
   457 datatypes and also for type `nat';
   458 
   459 * each datatype comes with a function `size';
   460 
   461 * patterns in case expressions allow tuple patterns as arguments to
   462 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
   463 
   464 * primrec now also works with type nat;
   465 
   466 * recdef: a new declaration form, allows general recursive functions to be
   467 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
   468 
   469 * the constant for negation has been renamed from "not" to "Not" to
   470 harmonize with FOL, ZF, LK, etc.;
   471 
   472 * HOL/ex/LFilter theory of a corecursive "filter" functional for
   473 infinite lists;
   474 
   475 * HOL/Modelcheck demonstrates invocation of model checker oracle;
   476 
   477 * HOL/ex/Ring.thy declares cring_simp, which solves equational
   478 problems in commutative rings, using axiomatic type classes for + and *;
   479 
   480 * more examples in HOL/MiniML and HOL/Auth;
   481 
   482 * more default rewrite rules for quantifiers, union/intersection;
   483 
   484 * a new constant `arbitrary == @x.False';
   485 
   486 * HOLCF/IOA replaces old HOL/IOA;
   487 
   488 * HOLCF changes: derived all rules and arities 
   489   + axiomatic type classes instead of classes 
   490   + typedef instead of faking type definitions
   491   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
   492   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
   493   + eliminated the types void, one, tr
   494   + use unit lift and bool lift (with translations) instead of one and tr
   495   + eliminated blift from Lift3.thy (use Def instead of blift)
   496   all eliminated rules are derived as theorems --> no visible changes ;
   497 
   498 
   499 *** ZF ***
   500 
   501 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
   502 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
   503 as ZF_cs addSIs [equalityI];
   504 
   505 
   506 
   507 New in Isabelle94-7 (November 96)
   508 ---------------------------------
   509 
   510 * allowing negative levels (as offsets) in prlev and choplev;
   511 
   512 * super-linear speedup for large simplifications;
   513 
   514 * FOL, ZF and HOL now use miniscoping: rewriting pushes
   515 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
   516 FAIL); can suppress it using the command Delsimps (ex_simps @
   517 all_simps); De Morgan laws are also now included, by default;
   518 
   519 * improved printing of ==>  :  ~:
   520 
   521 * new object-logic "Sequents" adds linear logic, while replacing LK
   522 and Modal (thanks to Sara Kalvala);
   523 
   524 * HOL/Auth: correctness proofs for authentication protocols;
   525 
   526 * HOL: new auto_tac combines rewriting and classical reasoning (many
   527 examples on HOL/Auth);
   528 
   529 * HOL: new command AddIffs for declaring theorems of the form P=Q to
   530 the rewriter and classical reasoner simultaneously;
   531 
   532 * function uresult no longer returns theorems in "standard" format;
   533 regain previous version by: val uresult = standard o uresult;
   534 
   535 
   536 
   537 New in Isabelle94-6
   538 -------------------
   539 
   540 * oracles -- these establish an interface between Isabelle and trusted
   541 external reasoners, which may deliver results as theorems;
   542 
   543 * proof objects (in particular record all uses of oracles);
   544 
   545 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
   546 
   547 * "constdefs" section in theory files;
   548 
   549 * "primrec" section (HOL) no longer requires names;
   550 
   551 * internal type "tactic" now simply "thm -> thm Sequence.seq";
   552 
   553 
   554 
   555 New in Isabelle94-5
   556 -------------------
   557 
   558 * reduced space requirements;
   559 
   560 * automatic HTML generation from theories;
   561 
   562 * theory files no longer require "..." (quotes) around most types;
   563 
   564 * new examples, including two proofs of the Church-Rosser theorem;
   565 
   566 * non-curried (1994) version of HOL is no longer distributed;
   567 
   568 
   569 
   570 New in Isabelle94-4
   571 -------------------
   572 
   573 * greatly reduced space requirements;
   574 
   575 * theory files (.thy) no longer require \...\ escapes at line breaks;
   576 
   577 * searchable theorem database (see the section "Retrieving theorems" on 
   578 page 8 of the Reference Manual);
   579 
   580 * new examples, including Grabczewski's monumental case study of the
   581 Axiom of Choice;
   582 
   583 * The previous version of HOL renamed to Old_HOL;
   584 
   585 * The new version of HOL (previously called CHOL) uses a curried syntax 
   586 for functions.  Application looks like f a b instead of f(a,b);
   587 
   588 * Mutually recursive inductive definitions finally work in HOL;
   589 
   590 * In ZF, pattern-matching on tuples is now available in all abstractions and
   591 translates to the operator "split";
   592 
   593 
   594 
   595 New in Isabelle94-3
   596 -------------------
   597 
   598 * new infix operator, addss, allowing the classical reasoner to 
   599 perform simplification at each step of its search.  Example:
   600 	fast_tac (cs addss ss)
   601 
   602 * a new logic, CHOL, the same as HOL, but with a curried syntax 
   603 for functions.  Application looks like f a b instead of f(a,b).  Also pairs 
   604 look like (a,b) instead of <a,b>;
   605 
   606 * PLEASE NOTE: CHOL will eventually replace HOL!
   607 
   608 * In CHOL, pattern-matching on tuples is now available in all abstractions.
   609 It translates to the operator "split".  A new theory of integers is available;
   610 
   611 * In ZF, integer numerals now denote two's-complement binary integers.
   612 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
   613 
   614 * Many new examples: I/O automata, Church-Rosser theorem, equivalents 
   615 of the Axiom of Choice;
   616 
   617 
   618 
   619 New in Isabelle94-2
   620 -------------------
   621 
   622 * Significantly faster resolution;  
   623 
   624 * the different sections in a .thy file can now be mixed and repeated
   625 freely;
   626 
   627 * Database of theorems for FOL, HOL and ZF.  New
   628 commands including qed, qed_goal and bind_thm store theorems in the database.
   629 
   630 * Simple database queries: return a named theorem (get_thm) or all theorems of
   631 a given theory (thms_of), or find out what theory a theorem was proved in
   632 (theory_of_thm);
   633 
   634 * Bugs fixed in the inductive definition and datatype packages;
   635 
   636 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
   637 and HOL_dup_cs obsolete;
   638 
   639 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
   640 have been removed;
   641 
   642 * Simpler definition of function space in ZF;
   643 
   644 * new results about cardinal and ordinal arithmetic in ZF;
   645 
   646 * 'subtype' facility in HOL for introducing new types as subsets of existing
   647 types;
   648 
   649 
   650 $Id$