NEWS
author wenzelm
Thu Jun 25 16:12:02 1998 +0200 (1998-06-25)
changeset 5085 8e5a7942fdea
parent 5077 71043526295f
child 5106 05b7c9a2ddf9
permissions -rw-r--r--
simplification procedure unit_eq_proc rewrites (?x::unit) = ();
quote / antiquote translations;
     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/record: now includes concrete syntax for record terms (still
    50 lacks important theorems, like surjective pairing and split);
    51 
    52 * simplification procedure unit_eq_proc rewrites (?x::unit) = (); this
    53 is made part of the default simpset of Prod.thy, which COULD MAKE
    54 EXISTING PROOFS FAIL (consider 'Delsimprocs [unit_eq_proc];' as last
    55 resort);
    56 
    57 * new force_tac (and its derivations Force_tac, force): combines
    58 rewriting and classical reasoning (and whatever other tools) similarly
    59 to auto_tac, but is aimed to solve the given subgoal totally;
    60 
    61 * added option_map_eq_Some to simpset() and claset()
    62 
    63 * New directory HOL/UNITY: Chandy and Misra's UNITY formalism
    64 
    65 * New theory HOL/Update of function updates:
    66   f(a:=b) == %x. if x=a then b else f x
    67   May also be iterated as in f(a:=b,c:=d,...).
    68 
    69 * HOL/List: new function list_update written xs[i:=v] that updates the i-th
    70   list position. May also be iterated as in xs[i:=a,j:=b,...].
    71 
    72 * split_all_tac is now much faster and fails if there is nothing to
    73 split.  Existing (fragile) proofs may require adaption because the
    74 order and the names of the automatically generated variables have
    75 changed.  split_all_tac has moved within claset() from usafe wrappers
    76 to safe wrappers, which means that !!-bound variables are splitted
    77 much more aggressively, and safe_tac and clarify_tac now split such
    78 variables.  If this splitting is not appropriate, use delSWrapper
    79 "split_all_tac".
    80 
    81 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
    82 
    83 * HOL/Arithmetic:
    84   
    85   - removed 'pred' (predecessor) function
    86   - generalized some theorems about n-1
    87   - Many new laws about "div" and "mod"
    88   - New laws about greatest common divisors (see theory ex/Primes)
    89 
    90 * HOL/Relation: renamed the relational operatotr r^-1 "converse"
    91 instead of "inverse";
    92 
    93 * recdef can now declare non-recursive functions, with {} supplied as
    94 the well-founded relation;
    95 
    96 * expand_if, expand_split, expand_sum_case and expand_nat_case are now called
    97   split_if, split_split, split_sum_case and split_nat_case
    98   (to go with add/delsplits).
    99 
   100 * Simplifier:
   101 
   102  -Rewrite rules for case distinctions can now be added permanently to the
   103   default simpset using Addsplits just like Addsimps. They can be removed via
   104   Delsplits just like Delsimps. Lower-case versions are also available.
   105 
   106  -The rule split_if is now part of the default simpset. This means that
   107   the simplifier will eliminate all ocurrences of if-then-else in the
   108   conclusion of a goal. To prevent this, you can either remove split_if
   109   completely from the default simpset by `Delsplits [split_if]' or
   110   remove it in a specific call of the simplifier using
   111   `... delsplits [split_if]'.
   112   You can also add/delete other case splitting rules to/from the default
   113   simpset: every datatype generates suitable rules `split_t_case' and
   114   `split_t_case_asm' (where t is the name of the datatype).
   115 
   116 * new theory Vimage (inverse image of a function, syntax f-``B);
   117 
   118 * many new identities for unions, intersections, set difference, etc.;
   119 
   120 
   121 *** ZF ***
   122 
   123 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
   124 
   125 
   126 *** Internal changes ***
   127 
   128 * improved the theory data mechanism to support encapsulation (data
   129 kind name replaced by private Object.kind, acting as authorization
   130 key); new type-safe user interface via functor TheoryDataFun;
   131 
   132 * module Pure/Syntax now offers quote / antiquote translation
   133 functions (useful for Hoare logic etc. with implicit dependencies);
   134 
   135 
   136 
   137 New in Isabelle98 (January 1998)
   138 --------------------------------
   139 
   140 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   141 
   142 * changed lexical syntax of terms / types: dots made part of long
   143 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
   144 
   145 * simpset (and claset) reference variable replaced by functions
   146 simpset / simpset_ref;
   147 
   148 * no longer supports theory aliases (via merge) and non-trivial
   149 implicit merge of thms' signatures;
   150 
   151 * most internal names of constants changed due to qualified names;
   152 
   153 * changed Pure/Sequence interface (see Pure/seq.ML);
   154 
   155 
   156 *** General Changes ***
   157 
   158 * hierachically structured name spaces (for consts, types, axms, thms
   159 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
   160 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
   161 isatool fixdots ensures space after dots (e.g. "%x. x"); set
   162 long_names for fully qualified output names; NOTE: ML programs
   163 (special tactics, packages etc.) referring to internal names may have
   164 to be adapted to cope with fully qualified names; in case of severe
   165 backward campatibility problems try setting 'global_names' at compile
   166 time to have enrything declared within a flat name space; one may also
   167 fine tune name declarations in theories via the 'global' and 'local'
   168 section;
   169 
   170 * reimplemented the implicit simpset and claset using the new anytype
   171 data filed in signatures; references simpset:simpset ref etc. are
   172 replaced by functions simpset:unit->simpset and
   173 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
   174 to patch your ML files accordingly;
   175 
   176 * HTML output now includes theory graph data for display with Java
   177 applet or isatool browser; data generated automatically via isatool
   178 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
   179 
   180 * defs may now be conditional; improved rewrite_goals_tac to handle
   181 conditional equations;
   182 
   183 * defs now admits additional type arguments, using TYPE('a) syntax;
   184 
   185 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
   186 creates a new theory node; implicit merge of thms' signatures is
   187 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
   188 transfer:theory->thm->thm in (rare) cases;
   189 
   190 * improved handling of draft signatures / theories; draft thms (and
   191 ctyps, cterms) are automatically promoted to real ones;
   192 
   193 * slightly changed interfaces for oracles: admit many per theory, named
   194 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
   195 
   196 * print_goals: optional output of const types (set show_consts and
   197 show_types);
   198 
   199 * improved output of warnings (###) and errors (***);
   200 
   201 * subgoal_tac displays a warning if the new subgoal has type variables;
   202 
   203 * removed old README and Makefiles;
   204 
   205 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
   206 
   207 * removed obsolete init_pps and init_database;
   208 
   209 * deleted the obsolete tactical STATE, which was declared by
   210     fun STATE tacfun st = tacfun st st;
   211 
   212 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
   213 (which abbreviates $HOME);
   214 
   215 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
   216 use isatool fixseq to adapt your ML programs (this works for fully
   217 qualified references to the Sequence structure only!);
   218 
   219 * use_thy no longer requires writable current directory; it always
   220 reloads .ML *and* .thy file, if either one is out of date;
   221 
   222 
   223 *** Classical Reasoner ***
   224 
   225 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
   226 tactics that use classical reasoning to simplify a subgoal without
   227 splitting it into several subgoals;
   228 
   229 * Safe_tac: like safe_tac but uses the default claset;
   230 
   231 
   232 *** Simplifier ***
   233 
   234 * added simplification meta rules:
   235     (asm_)(full_)simplify: simpset -> thm -> thm;
   236 
   237 * simplifier.ML no longer part of Pure -- has to be loaded by object
   238 logics (again);
   239 
   240 * added prems argument to simplification procedures;
   241 
   242 * HOL, FOL, ZF: added infix function `addsplits':
   243   instead of `<simpset> setloop (split_tac <thms>)'
   244   you can simply write `<simpset> addsplits <thms>'
   245 
   246 
   247 *** Syntax ***
   248 
   249 * TYPE('a) syntax for type reflection terms;
   250 
   251 * no longer handles consts with name "" -- declare as 'syntax' instead;
   252 
   253 * pretty printer: changed order of mixfix annotation preference (again!);
   254 
   255 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
   256 
   257 
   258 *** HOL ***
   259 
   260 * HOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   261   with `addloop' of the simplifier to faciliate case splitting in premises.
   262 
   263 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
   264 
   265 * HOL/Auth: new protocol proofs including some for the Internet
   266   protocol TLS;
   267 
   268 * HOL/Map: new theory of `maps' a la VDM;
   269 
   270 * HOL/simplifier: simplification procedures nat_cancel_sums for
   271 cancelling out common nat summands from =, <, <= (in)equalities, or
   272 differences; simplification procedures nat_cancel_factor for
   273 cancelling common factor from =, <, <= (in)equalities over natural
   274 sums; nat_cancel contains both kinds of procedures, it is installed by
   275 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
   276 
   277 * HOL/simplifier: terms of the form
   278   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
   279   are rewritten to
   280   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
   281   and those of the form
   282   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
   283   are rewritten to
   284   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
   285 
   286 * HOL/datatype
   287   Each datatype `t' now comes with a theorem `split_t_case' of the form
   288 
   289   P(t_case f1 ... fn x) =
   290      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
   291         ...
   292        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
   293      )
   294 
   295   and a theorem `split_t_case_asm' of the form
   296 
   297   P(t_case f1 ... fn x) =
   298     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
   299         ...
   300        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
   301      )
   302   which can be added to a simpset via `addsplits'. The existing theorems
   303   expand_list_case and expand_option_case have been renamed to
   304   split_list_case and split_option_case.
   305 
   306 * HOL/Arithmetic:
   307   - `pred n' is automatically converted to `n-1'.
   308     Users are strongly encouraged not to use `pred' any longer,
   309     because it will disappear altogether at some point.
   310   - Users are strongly encouraged to write "0 < n" rather than
   311     "n ~= 0". Theorems and proof tools have been modified towards this
   312     `standard'.
   313 
   314 * HOL/Lists:
   315   the function "set_of_list" has been renamed "set" (and its theorems too);
   316   the function "nth" now takes its arguments in the reverse order and
   317   has acquired the infix notation "!" as in "xs!n".
   318 
   319 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
   320 
   321 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
   322   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
   323 
   324 * HOL/record: extensible records with schematic structural subtyping
   325 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
   326 still lacks various theorems and concrete record syntax;
   327 
   328 
   329 *** HOLCF ***
   330 
   331 * removed "axioms" and "generated by" sections;
   332 
   333 * replaced "ops" section by extended "consts" section, which is capable of
   334   handling the continuous function space "->" directly;
   335 
   336 * domain package:
   337   . proves theorems immediately and stores them in the theory,
   338   . creates hierachical name space,
   339   . now uses normal mixfix annotations (instead of cinfix...),
   340   . minor changes to some names and values (for consistency),
   341   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
   342   . separator between mutual domain defs: changed "," to "and",
   343   . improved handling of sort constraints;  now they have to
   344     appear on the left-hand side of the equations only;
   345 
   346 * fixed LAM <x,y,zs>.b syntax;
   347 
   348 * added extended adm_tac to simplifier in HOLCF -- can now discharge
   349 adm (%x. P (t x)), where P is chainfinite and t continuous;
   350 
   351 
   352 *** FOL and ZF ***
   353 
   354 * FOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   355   with `addloop' of the simplifier to faciliate case splitting in premises.
   356 
   357 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
   358 in HOL, they strip ALL and --> from proved theorems;
   359 
   360 
   361 
   362 New in Isabelle94-8 (May 1997)
   363 ------------------------------
   364 
   365 *** General Changes ***
   366 
   367 * new utilities to build / run / maintain Isabelle etc. (in parts
   368 still somewhat experimental); old Makefiles etc. still functional;
   369 
   370 * new 'Isabelle System Manual';
   371 
   372 * INSTALL text, together with ./configure and ./build scripts;
   373 
   374 * reimplemented type inference for greater efficiency, better error
   375 messages and clean internal interface;
   376 
   377 * prlim command for dealing with lots of subgoals (an easier way of
   378 setting goals_limit);
   379 
   380 
   381 *** Syntax ***
   382 
   383 * supports alternative (named) syntax tables (parser and pretty
   384 printer); internal interface is provided by add_modesyntax(_i);
   385 
   386 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
   387 be used in conjunction with the Isabelle symbol font; uses the
   388 "symbols" syntax table;
   389 
   390 * added token_translation interface (may translate name tokens in
   391 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
   392 the current print_mode); IMPORTANT: user print translation functions
   393 are responsible for marking newly introduced bounds
   394 (Syntax.mark_boundT);
   395 
   396 * token translations for modes "xterm" and "xterm_color" that display
   397 names in bold, underline etc. or colors (which requires a color
   398 version of xterm);
   399 
   400 * infixes may now be declared with names independent of their syntax;
   401 
   402 * added typed_print_translation (like print_translation, but may
   403 access type of constant);
   404 
   405 
   406 *** Classical Reasoner ***
   407 
   408 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
   409 some limitations.  Blast_tac...
   410   + ignores addss, addbefore, addafter; this restriction is intrinsic
   411   + ignores elimination rules that don't have the correct format
   412 	(the conclusion MUST be a formula variable)
   413   + ignores types, which can make HOL proofs fail
   414   + rules must not require higher-order unification, e.g. apply_type in ZF
   415     [message "Function Var's argument not a bound variable" relates to this]
   416   + its proof strategy is more general but can actually be slower
   417 
   418 * substitution with equality assumptions no longer permutes other
   419 assumptions;
   420 
   421 * minor changes in semantics of addafter (now called addaltern); renamed
   422 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
   423 (and access functions for it);
   424 
   425 * improved combination of classical reasoner and simplifier: 
   426   + functions for handling clasimpsets
   427   + improvement of addss: now the simplifier is called _after_ the
   428     safe steps.
   429   + safe variant of addss called addSss: uses safe simplifications
   430     _during_ the safe steps. It is more complete as it allows multiple 
   431     instantiations of unknowns (e.g. with slow_tac).
   432 
   433 *** Simplifier ***
   434 
   435 * added interface for simplification procedures (functions that
   436 produce *proven* rewrite rules on the fly, depending on current
   437 redex);
   438 
   439 * ordering on terms as parameter (used for ordered rewriting);
   440 
   441 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
   442 
   443 * the solver is now split into a safe and an unsafe part.
   444 This should be invisible for the normal user, except that the
   445 functions setsolver and addsolver have been renamed to setSolver and
   446 addSolver; added safe_asm_full_simp_tac;
   447 
   448 
   449 *** HOL ***
   450 
   451 * a generic induction tactic `induct_tac' which works for all datatypes and
   452 also for type `nat';
   453 
   454 * a generic case distinction tactic `exhaust_tac' which works for all
   455 datatypes and also for type `nat';
   456 
   457 * each datatype comes with a function `size';
   458 
   459 * patterns in case expressions allow tuple patterns as arguments to
   460 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
   461 
   462 * primrec now also works with type nat;
   463 
   464 * recdef: a new declaration form, allows general recursive functions to be
   465 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
   466 
   467 * the constant for negation has been renamed from "not" to "Not" to
   468 harmonize with FOL, ZF, LK, etc.;
   469 
   470 * HOL/ex/LFilter theory of a corecursive "filter" functional for
   471 infinite lists;
   472 
   473 * HOL/Modelcheck demonstrates invocation of model checker oracle;
   474 
   475 * HOL/ex/Ring.thy declares cring_simp, which solves equational
   476 problems in commutative rings, using axiomatic type classes for + and *;
   477 
   478 * more examples in HOL/MiniML and HOL/Auth;
   479 
   480 * more default rewrite rules for quantifiers, union/intersection;
   481 
   482 * a new constant `arbitrary == @x.False';
   483 
   484 * HOLCF/IOA replaces old HOL/IOA;
   485 
   486 * HOLCF changes: derived all rules and arities 
   487   + axiomatic type classes instead of classes 
   488   + typedef instead of faking type definitions
   489   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
   490   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
   491   + eliminated the types void, one, tr
   492   + use unit lift and bool lift (with translations) instead of one and tr
   493   + eliminated blift from Lift3.thy (use Def instead of blift)
   494   all eliminated rules are derived as theorems --> no visible changes ;
   495 
   496 
   497 *** ZF ***
   498 
   499 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
   500 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
   501 as ZF_cs addSIs [equalityI];
   502 
   503 
   504 
   505 New in Isabelle94-7 (November 96)
   506 ---------------------------------
   507 
   508 * allowing negative levels (as offsets) in prlev and choplev;
   509 
   510 * super-linear speedup for large simplifications;
   511 
   512 * FOL, ZF and HOL now use miniscoping: rewriting pushes
   513 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
   514 FAIL); can suppress it using the command Delsimps (ex_simps @
   515 all_simps); De Morgan laws are also now included, by default;
   516 
   517 * improved printing of ==>  :  ~:
   518 
   519 * new object-logic "Sequents" adds linear logic, while replacing LK
   520 and Modal (thanks to Sara Kalvala);
   521 
   522 * HOL/Auth: correctness proofs for authentication protocols;
   523 
   524 * HOL: new auto_tac combines rewriting and classical reasoning (many
   525 examples on HOL/Auth);
   526 
   527 * HOL: new command AddIffs for declaring theorems of the form P=Q to
   528 the rewriter and classical reasoner simultaneously;
   529 
   530 * function uresult no longer returns theorems in "standard" format;
   531 regain previous version by: val uresult = standard o uresult;
   532 
   533 
   534 
   535 New in Isabelle94-6
   536 -------------------
   537 
   538 * oracles -- these establish an interface between Isabelle and trusted
   539 external reasoners, which may deliver results as theorems;
   540 
   541 * proof objects (in particular record all uses of oracles);
   542 
   543 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
   544 
   545 * "constdefs" section in theory files;
   546 
   547 * "primrec" section (HOL) no longer requires names;
   548 
   549 * internal type "tactic" now simply "thm -> thm Sequence.seq";
   550 
   551 
   552 
   553 New in Isabelle94-5
   554 -------------------
   555 
   556 * reduced space requirements;
   557 
   558 * automatic HTML generation from theories;
   559 
   560 * theory files no longer require "..." (quotes) around most types;
   561 
   562 * new examples, including two proofs of the Church-Rosser theorem;
   563 
   564 * non-curried (1994) version of HOL is no longer distributed;
   565 
   566 
   567 
   568 New in Isabelle94-4
   569 -------------------
   570 
   571 * greatly reduced space requirements;
   572 
   573 * theory files (.thy) no longer require \...\ escapes at line breaks;
   574 
   575 * searchable theorem database (see the section "Retrieving theorems" on 
   576 page 8 of the Reference Manual);
   577 
   578 * new examples, including Grabczewski's monumental case study of the
   579 Axiom of Choice;
   580 
   581 * The previous version of HOL renamed to Old_HOL;
   582 
   583 * The new version of HOL (previously called CHOL) uses a curried syntax 
   584 for functions.  Application looks like f a b instead of f(a,b);
   585 
   586 * Mutually recursive inductive definitions finally work in HOL;
   587 
   588 * In ZF, pattern-matching on tuples is now available in all abstractions and
   589 translates to the operator "split";
   590 
   591 
   592 
   593 New in Isabelle94-3
   594 -------------------
   595 
   596 * new infix operator, addss, allowing the classical reasoner to 
   597 perform simplification at each step of its search.  Example:
   598 	fast_tac (cs addss ss)
   599 
   600 * a new logic, CHOL, the same as HOL, but with a curried syntax 
   601 for functions.  Application looks like f a b instead of f(a,b).  Also pairs 
   602 look like (a,b) instead of <a,b>;
   603 
   604 * PLEASE NOTE: CHOL will eventually replace HOL!
   605 
   606 * In CHOL, pattern-matching on tuples is now available in all abstractions.
   607 It translates to the operator "split".  A new theory of integers is available;
   608 
   609 * In ZF, integer numerals now denote two's-complement binary integers.
   610 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
   611 
   612 * Many new examples: I/O automata, Church-Rosser theorem, equivalents 
   613 of the Axiom of Choice;
   614 
   615 
   616 
   617 New in Isabelle94-2
   618 -------------------
   619 
   620 * Significantly faster resolution;  
   621 
   622 * the different sections in a .thy file can now be mixed and repeated
   623 freely;
   624 
   625 * Database of theorems for FOL, HOL and ZF.  New
   626 commands including qed, qed_goal and bind_thm store theorems in the database.
   627 
   628 * Simple database queries: return a named theorem (get_thm) or all theorems of
   629 a given theory (thms_of), or find out what theory a theorem was proved in
   630 (theory_of_thm);
   631 
   632 * Bugs fixed in the inductive definition and datatype packages;
   633 
   634 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
   635 and HOL_dup_cs obsolete;
   636 
   637 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
   638 have been removed;
   639 
   640 * Simpler definition of function space in ZF;
   641 
   642 * new results about cardinal and ordinal arithmetic in ZF;
   643 
   644 * 'subtype' facility in HOL for introducing new types as subsets of existing
   645 types;
   646 
   647 
   648 $Id$