NEWS
author wenzelm
Thu Jul 30 17:06:54 1998 +0200 (1998-07-30)
changeset 5217 3ecd7c952396
parent 5214 75c6392d1274
child 5226 89934cd022a9
permissions -rw-r--r--
tuned;
     1 
     2 Isabelle NEWS -- history of user-visible changes
     3 ================================================
     4 
     5 New in this Isabelle version
     6 ----------------------------
     7 
     8 *** Overview of INCOMPATIBILITIES (see below for more details) ***
     9 
    10 * several changes of proof tools;
    11 
    12 * HOL: major changes to the inductive and datatype packages;
    13 
    14 * HOL: renamed r^-1 to 'converse' from 'inverse'; `inj_onto' is now
    15 called `inj_on';
    16 
    17 
    18 *** Proof tools ***
    19 
    20 * Simplifier: Asm_full_simp_tac is now more aggressive.
    21   1. It will sometimes reorient premises if that increases their power to
    22      simplify.
    23   2. It does no longer proceed strictly from left to right but may also
    24      rotate premises to achieve further simplification.
    25   For compatibility reasons there is now Asm_lr_simp_tac which is like the
    26   old Asm_full_simp_tac in that it does not rotate premises.
    27 
    28 * Classical reasoner: wrapper mechanism for the classical reasoner now
    29 allows for selected deletion of wrappers, by introduction of names for
    30 wrapper functionals.  This implies that addbefore, addSbefore,
    31 addaltern, and addSaltern now take a pair (name, tactic) as argument,
    32 and that adding two tactics with the same name overwrites the first
    33 one (emitting a warning).
    34   type wrapper = (int -> tactic) -> (int -> tactic)
    35   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
    36   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
    37   delWrapper, delSWrapper: claset *  string            -> claset
    38   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
    39 
    40 * HOL/split_all_tac is now much faster and fails if there is nothing
    41 to split.  Existing (fragile) proofs may require adaption because the
    42 order and the names of the automatically generated variables have
    43 changed.  split_all_tac has moved within claset() from unsafe wrappers
    44 to safe wrappers, which means that !!-bound variables are split much
    45 more aggressively, and safe_tac and clarify_tac now split such
    46 variables.  If this splitting is not appropriate, use delSWrapper
    47 "split_all_tac".
    48 
    49 * HOL/Simplifier:
    50 
    51  - Rewrite rules for case distinctions can now be added permanently to
    52    the default simpset using Addsplits just like Addsimps. They can be
    53    removed via Delsplits just like Delsimps. Lower-case versions are
    54    also available.
    55 
    56  - The rule split_if is now part of the default simpset. This means
    57    that the simplifier will eliminate all occurrences of if-then-else
    58    in the conclusion of a goal. To prevent this, you can either remove
    59    split_if completely from the default simpset by `Delsplits
    60    [split_if]' or remove it in a specific call of the simplifier using
    61    `... delsplits [split_if]'.  You can also add/delete other case
    62    splitting rules to/from the default simpset: every datatype
    63    generates suitable rules `split_t_case' and `split_t_case_asm'
    64    (where t is the name of the datatype).
    65 
    66 * Classical reasoner - Simplifier combination: new force_tac (and
    67 derivatives Force_tac, force) combines rewriting and classical
    68 reasoning (and whatever other tools) similarly to auto_tac, but is
    69 aimed to solve the given subgoal completely;
    70 
    71 
    72 *** General ***
    73 
    74 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
    75 and `goalw': the theory is no longer needed as an explicit argument -
    76 the current theory context is used; assumptions are no longer returned
    77 at the ML-level unless one of them starts with ==> or !!; it is
    78 recommended to convert to these new commands using isatool fixgoal
    79 (backup your sources first!);
    80 
    81 * new top-level commands 'thm' and 'thms' for retrieving theorems from
    82 the current theory context, and 'theory' to lookup stored theories;
    83 
    84 * new theory section 'nonterminals' for purely syntactic types;
    85 
    86 * new theory section 'setup' for generic ML setup functions
    87 (e.g. package initialization);
    88 
    89 * the distribution now includes Isabelle icons: see
    90 lib/logo/isabelle-{small,tiny}.xpm;
    91 
    92 
    93 *** HOL ***
    94 
    95 * HOL/inductive package reorganized and improved: now supports mutual
    96 definitions such as:
    97 
    98   inductive EVEN ODD
    99     intrs
   100       null "0 : EVEN"
   101       oddI "n : EVEN ==> Suc n : ODD"
   102       evenI "n : ODD ==> Suc n : EVEN"
   103 
   104 new theorem list "elims" contains an elimination rule for each of the
   105 recursive sets; inductive definitions now handle disjunctive premises
   106 correctly (also ZF);
   107 
   108 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   109 "mutual_induct" no longer exists - the induction rule is always
   110 contained in "induct";
   111 
   112 
   113 * HOL/datatype package re-implemented and greatly improved: now
   114 supports mutually recursive datatypes such as:
   115 
   116   datatype
   117     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
   118             | SUM ('a aexp) ('a aexp)
   119             | DIFF ('a aexp) ('a aexp)
   120             | NUM 'a
   121   and
   122     'a bexp = LESS ('a aexp) ('a aexp)
   123             | AND ('a bexp) ('a bexp)
   124             | OR ('a bexp) ('a bexp)
   125 
   126 as well as indirectly recursive datatypes such as:
   127 
   128   datatype
   129     ('a, 'b) term = Var 'a
   130                   | App 'b ((('a, 'b) term) list)
   131 
   132 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
   133 induction on mutually / indirectly recursive datatypes.
   134 
   135 Primrec equations are now stored in theory and can be accessed via
   136 <function_name>.simps.
   137 
   138 INCOMPATIBILITIES:
   139 
   140   - Theories using datatypes must now have theory Datatype as an
   141     ancestor.
   142   - The specific <typename>.induct_tac no longer exists - use the
   143     generic induct_tac instead.
   144   - natE has been renamed to nat.exhaustion - use exhaust_tac
   145     instead of res_inst_tac ... natE. Note that the variable
   146     names in nat.exhaustion differ from the names in natE, this
   147     may cause some "fragile" proofs to fail.
   148   - The theorems split_<typename>_case and split_<typename>_case_asm
   149     have been renamed to <typename>.split and <typename>.split_asm.
   150   - Since default sorts of type variables are now handled correctly,
   151     some datatype definitions may have to be annotated with explicit
   152     sort constraints.
   153   - Primrec definitions no longer require function name and type
   154     of recursive argument.
   155 
   156 Consider using isatool fixdatatype to adapt your theories and proof
   157 scripts to the new package (backup your sources first!).
   158 
   159 
   160 * HOL/record package: now includes concrete syntax for record types,
   161 terms, updates; still lacks important theorems, like surjective
   162 pairing and split;
   163 
   164 * reorganized the main HOL image: HOL/Integ and String loaded by
   165 default; theory Main includes everything;
   166 
   167 * added option_map_eq_Some to the default simpset claset;
   168 
   169 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
   170 
   171 * many new identities for unions, intersections, set difference, etc.;
   172 
   173 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
   174 called split_if, split_split, split_sum_case and split_nat_case (to go
   175 with add/delsplits);
   176 
   177 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
   178 (?x::unit) = (); this is made part of the default simpset, which COULD
   179 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
   180 'Delsimprocs [unit_eq_proc];' as last resort); also note that
   181 unit_abs_eta_conv is added in order to counter the effect of
   182 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
   183 %u.f();
   184 
   185 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
   186 makes more sense);
   187 
   188 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
   189 to 'converse' from 'inverse' (for compatibility with ZF and some
   190 literature);
   191 
   192 * HOL/recdef can now declare non-recursive functions, with {} supplied as
   193 the well-founded relation;
   194 
   195 * HOL/Update: new theory of function updates:
   196     f(a:=b) == %x. if x=a then b else f x
   197 may also be iterated as in f(a:=b,c:=d,...);
   198 
   199 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
   200 
   201 * HOL/List: new function list_update written xs[i:=v] that updates the i-th
   202   list position. May also be iterated as in xs[i:=a,j:=b,...].
   203 
   204 * HOL/Arith:
   205   - removed 'pred' (predecessor) function;
   206   - generalized some theorems about n-1;
   207   - many new laws about "div" and "mod";
   208   - new laws about greatest common divisors (see theory ex/Primes);
   209 
   210 * HOL/Relation: renamed the relational operator r^-1 "converse"
   211 instead of "inverse";
   212 
   213 * HOL/Set: added the predicate "disjoint A B" that stands for "A <= Compl B".
   214   This is much better than "A Int B = {}" for Fast/Blast_tac.
   215 
   216 * directory HOL/Real: a construction of the reals using Dedekind cuts
   217 (not included by default);
   218 
   219 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
   220 
   221 * calling (stac rew i) now fails if "rew" has no effect on the goal
   222   [previously, this check worked only if the rewrite rule was unconditional]
   223 
   224 
   225 *** ZF ***
   226 
   227 * theory Main includes everything;
   228 
   229 * ZF/Update: new theory of function updates
   230     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
   231   may also be iterated as in f(a:=b,c:=d,...);
   232 
   233 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
   234 
   235 * calling (stac rew i) now fails if "rew" has no effect on the goal
   236   [previously, this check worked only if the rewrite rule was unconditional]
   237 
   238 * case_tac provided for compatibility with HOL
   239     (like the old excluded_middle_tac, but with subgoals swapped)
   240 
   241 
   242 *** Internal programming interfaces ***
   243 
   244 * removed global_names compatibility flag -- all theory declarations
   245 are qualified by default;
   246 
   247 * improved the theory data mechanism to support encapsulation (data
   248 kind name replaced by private Object.kind, acting as authorization
   249 key); new type-safe user interface via functor TheoryDataFun;
   250 
   251 * module Pure/Syntax now offers quote / antiquote translation
   252 functions (useful for Hoare logic etc. with implicit dependencies);
   253 
   254 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
   255 cterm -> thm;
   256 
   257 * Pure: several new basic modules made available for general use, see
   258 also src/Pure/README;
   259 
   260 * new tactical CHANGED_GOAL for checking that a tactic modifies a
   261 subgoal;
   262 
   263 
   264 
   265 New in Isabelle98 (January 1998)
   266 --------------------------------
   267 
   268 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   269 
   270 * changed lexical syntax of terms / types: dots made part of long
   271 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
   272 
   273 * simpset (and claset) reference variable replaced by functions
   274 simpset / simpset_ref;
   275 
   276 * no longer supports theory aliases (via merge) and non-trivial
   277 implicit merge of thms' signatures;
   278 
   279 * most internal names of constants changed due to qualified names;
   280 
   281 * changed Pure/Sequence interface (see Pure/seq.ML);
   282 
   283 
   284 *** General Changes ***
   285 
   286 * hierachically structured name spaces (for consts, types, axms, thms
   287 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
   288 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
   289 isatool fixdots ensures space after dots (e.g. "%x. x"); set
   290 long_names for fully qualified output names; NOTE: ML programs
   291 (special tactics, packages etc.) referring to internal names may have
   292 to be adapted to cope with fully qualified names; in case of severe
   293 backward campatibility problems try setting 'global_names' at compile
   294 time to have enrything declared within a flat name space; one may also
   295 fine tune name declarations in theories via the 'global' and 'local'
   296 section;
   297 
   298 * reimplemented the implicit simpset and claset using the new anytype
   299 data filed in signatures; references simpset:simpset ref etc. are
   300 replaced by functions simpset:unit->simpset and
   301 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
   302 to patch your ML files accordingly;
   303 
   304 * HTML output now includes theory graph data for display with Java
   305 applet or isatool browser; data generated automatically via isatool
   306 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
   307 
   308 * defs may now be conditional; improved rewrite_goals_tac to handle
   309 conditional equations;
   310 
   311 * defs now admits additional type arguments, using TYPE('a) syntax;
   312 
   313 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
   314 creates a new theory node; implicit merge of thms' signatures is
   315 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
   316 transfer:theory->thm->thm in (rare) cases;
   317 
   318 * improved handling of draft signatures / theories; draft thms (and
   319 ctyps, cterms) are automatically promoted to real ones;
   320 
   321 * slightly changed interfaces for oracles: admit many per theory, named
   322 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
   323 
   324 * print_goals: optional output of const types (set show_consts and
   325 show_types);
   326 
   327 * improved output of warnings (###) and errors (***);
   328 
   329 * subgoal_tac displays a warning if the new subgoal has type variables;
   330 
   331 * removed old README and Makefiles;
   332 
   333 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
   334 
   335 * removed obsolete init_pps and init_database;
   336 
   337 * deleted the obsolete tactical STATE, which was declared by
   338     fun STATE tacfun st = tacfun st st;
   339 
   340 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
   341 (which abbreviates $HOME);
   342 
   343 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
   344 use isatool fixseq to adapt your ML programs (this works for fully
   345 qualified references to the Sequence structure only!);
   346 
   347 * use_thy no longer requires writable current directory; it always
   348 reloads .ML *and* .thy file, if either one is out of date;
   349 
   350 
   351 *** Classical Reasoner ***
   352 
   353 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
   354 tactics that use classical reasoning to simplify a subgoal without
   355 splitting it into several subgoals;
   356 
   357 * Safe_tac: like safe_tac but uses the default claset;
   358 
   359 
   360 *** Simplifier ***
   361 
   362 * added simplification meta rules:
   363     (asm_)(full_)simplify: simpset -> thm -> thm;
   364 
   365 * simplifier.ML no longer part of Pure -- has to be loaded by object
   366 logics (again);
   367 
   368 * added prems argument to simplification procedures;
   369 
   370 * HOL, FOL, ZF: added infix function `addsplits':
   371   instead of `<simpset> setloop (split_tac <thms>)'
   372   you can simply write `<simpset> addsplits <thms>'
   373 
   374 
   375 *** Syntax ***
   376 
   377 * TYPE('a) syntax for type reflection terms;
   378 
   379 * no longer handles consts with name "" -- declare as 'syntax' instead;
   380 
   381 * pretty printer: changed order of mixfix annotation preference (again!);
   382 
   383 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
   384 
   385 
   386 *** HOL ***
   387 
   388 * HOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   389   with `addloop' of the simplifier to faciliate case splitting in premises.
   390 
   391 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
   392 
   393 * HOL/Auth: new protocol proofs including some for the Internet
   394   protocol TLS;
   395 
   396 * HOL/Map: new theory of `maps' a la VDM;
   397 
   398 * HOL/simplifier: simplification procedures nat_cancel_sums for
   399 cancelling out common nat summands from =, <, <= (in)equalities, or
   400 differences; simplification procedures nat_cancel_factor for
   401 cancelling common factor from =, <, <= (in)equalities over natural
   402 sums; nat_cancel contains both kinds of procedures, it is installed by
   403 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
   404 
   405 * HOL/simplifier: terms of the form
   406   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
   407   are rewritten to
   408   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
   409   and those of the form
   410   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
   411   are rewritten to
   412   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
   413 
   414 * HOL/datatype
   415   Each datatype `t' now comes with a theorem `split_t_case' of the form
   416 
   417   P(t_case f1 ... fn x) =
   418      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
   419         ...
   420        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
   421      )
   422 
   423   and a theorem `split_t_case_asm' of the form
   424 
   425   P(t_case f1 ... fn x) =
   426     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
   427         ...
   428        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
   429      )
   430   which can be added to a simpset via `addsplits'. The existing theorems
   431   expand_list_case and expand_option_case have been renamed to
   432   split_list_case and split_option_case.
   433 
   434 * HOL/Arithmetic:
   435   - `pred n' is automatically converted to `n-1'.
   436     Users are strongly encouraged not to use `pred' any longer,
   437     because it will disappear altogether at some point.
   438   - Users are strongly encouraged to write "0 < n" rather than
   439     "n ~= 0". Theorems and proof tools have been modified towards this
   440     `standard'.
   441 
   442 * HOL/Lists:
   443   the function "set_of_list" has been renamed "set" (and its theorems too);
   444   the function "nth" now takes its arguments in the reverse order and
   445   has acquired the infix notation "!" as in "xs!n".
   446 
   447 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
   448 
   449 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
   450   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
   451 
   452 * HOL/record: extensible records with schematic structural subtyping
   453 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
   454 still lacks various theorems and concrete record syntax;
   455 
   456 
   457 *** HOLCF ***
   458 
   459 * removed "axioms" and "generated by" sections;
   460 
   461 * replaced "ops" section by extended "consts" section, which is capable of
   462   handling the continuous function space "->" directly;
   463 
   464 * domain package:
   465   . proves theorems immediately and stores them in the theory,
   466   . creates hierachical name space,
   467   . now uses normal mixfix annotations (instead of cinfix...),
   468   . minor changes to some names and values (for consistency),
   469   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
   470   . separator between mutual domain defs: changed "," to "and",
   471   . improved handling of sort constraints;  now they have to
   472     appear on the left-hand side of the equations only;
   473 
   474 * fixed LAM <x,y,zs>.b syntax;
   475 
   476 * added extended adm_tac to simplifier in HOLCF -- can now discharge
   477 adm (%x. P (t x)), where P is chainfinite and t continuous;
   478 
   479 
   480 *** FOL and ZF ***
   481 
   482 * FOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   483   with `addloop' of the simplifier to faciliate case splitting in premises.
   484 
   485 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
   486 in HOL, they strip ALL and --> from proved theorems;
   487 
   488 
   489 
   490 New in Isabelle94-8 (May 1997)
   491 ------------------------------
   492 
   493 *** General Changes ***
   494 
   495 * new utilities to build / run / maintain Isabelle etc. (in parts
   496 still somewhat experimental); old Makefiles etc. still functional;
   497 
   498 * new 'Isabelle System Manual';
   499 
   500 * INSTALL text, together with ./configure and ./build scripts;
   501 
   502 * reimplemented type inference for greater efficiency, better error
   503 messages and clean internal interface;
   504 
   505 * prlim command for dealing with lots of subgoals (an easier way of
   506 setting goals_limit);
   507 
   508 
   509 *** Syntax ***
   510 
   511 * supports alternative (named) syntax tables (parser and pretty
   512 printer); internal interface is provided by add_modesyntax(_i);
   513 
   514 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
   515 be used in conjunction with the Isabelle symbol font; uses the
   516 "symbols" syntax table;
   517 
   518 * added token_translation interface (may translate name tokens in
   519 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
   520 the current print_mode); IMPORTANT: user print translation functions
   521 are responsible for marking newly introduced bounds
   522 (Syntax.mark_boundT);
   523 
   524 * token translations for modes "xterm" and "xterm_color" that display
   525 names in bold, underline etc. or colors (which requires a color
   526 version of xterm);
   527 
   528 * infixes may now be declared with names independent of their syntax;
   529 
   530 * added typed_print_translation (like print_translation, but may
   531 access type of constant);
   532 
   533 
   534 *** Classical Reasoner ***
   535 
   536 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
   537 some limitations.  Blast_tac...
   538   + ignores addss, addbefore, addafter; this restriction is intrinsic
   539   + ignores elimination rules that don't have the correct format
   540 	(the conclusion MUST be a formula variable)
   541   + ignores types, which can make HOL proofs fail
   542   + rules must not require higher-order unification, e.g. apply_type in ZF
   543     [message "Function Var's argument not a bound variable" relates to this]
   544   + its proof strategy is more general but can actually be slower
   545 
   546 * substitution with equality assumptions no longer permutes other
   547 assumptions;
   548 
   549 * minor changes in semantics of addafter (now called addaltern); renamed
   550 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
   551 (and access functions for it);
   552 
   553 * improved combination of classical reasoner and simplifier: 
   554   + functions for handling clasimpsets
   555   + improvement of addss: now the simplifier is called _after_ the
   556     safe steps.
   557   + safe variant of addss called addSss: uses safe simplifications
   558     _during_ the safe steps. It is more complete as it allows multiple 
   559     instantiations of unknowns (e.g. with slow_tac).
   560 
   561 *** Simplifier ***
   562 
   563 * added interface for simplification procedures (functions that
   564 produce *proven* rewrite rules on the fly, depending on current
   565 redex);
   566 
   567 * ordering on terms as parameter (used for ordered rewriting);
   568 
   569 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
   570 
   571 * the solver is now split into a safe and an unsafe part.
   572 This should be invisible for the normal user, except that the
   573 functions setsolver and addsolver have been renamed to setSolver and
   574 addSolver; added safe_asm_full_simp_tac;
   575 
   576 
   577 *** HOL ***
   578 
   579 * a generic induction tactic `induct_tac' which works for all datatypes and
   580 also for type `nat';
   581 
   582 * a generic case distinction tactic `exhaust_tac' which works for all
   583 datatypes and also for type `nat';
   584 
   585 * each datatype comes with a function `size';
   586 
   587 * patterns in case expressions allow tuple patterns as arguments to
   588 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
   589 
   590 * primrec now also works with type nat;
   591 
   592 * recdef: a new declaration form, allows general recursive functions to be
   593 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
   594 
   595 * the constant for negation has been renamed from "not" to "Not" to
   596 harmonize with FOL, ZF, LK, etc.;
   597 
   598 * HOL/ex/LFilter theory of a corecursive "filter" functional for
   599 infinite lists;
   600 
   601 * HOL/Modelcheck demonstrates invocation of model checker oracle;
   602 
   603 * HOL/ex/Ring.thy declares cring_simp, which solves equational
   604 problems in commutative rings, using axiomatic type classes for + and *;
   605 
   606 * more examples in HOL/MiniML and HOL/Auth;
   607 
   608 * more default rewrite rules for quantifiers, union/intersection;
   609 
   610 * a new constant `arbitrary == @x.False';
   611 
   612 * HOLCF/IOA replaces old HOL/IOA;
   613 
   614 * HOLCF changes: derived all rules and arities 
   615   + axiomatic type classes instead of classes 
   616   + typedef instead of faking type definitions
   617   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
   618   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
   619   + eliminated the types void, one, tr
   620   + use unit lift and bool lift (with translations) instead of one and tr
   621   + eliminated blift from Lift3.thy (use Def instead of blift)
   622   all eliminated rules are derived as theorems --> no visible changes ;
   623 
   624 
   625 *** ZF ***
   626 
   627 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
   628 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
   629 as ZF_cs addSIs [equalityI];
   630 
   631 
   632 
   633 New in Isabelle94-7 (November 96)
   634 ---------------------------------
   635 
   636 * allowing negative levels (as offsets) in prlev and choplev;
   637 
   638 * super-linear speedup for large simplifications;
   639 
   640 * FOL, ZF and HOL now use miniscoping: rewriting pushes
   641 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
   642 FAIL); can suppress it using the command Delsimps (ex_simps @
   643 all_simps); De Morgan laws are also now included, by default;
   644 
   645 * improved printing of ==>  :  ~:
   646 
   647 * new object-logic "Sequents" adds linear logic, while replacing LK
   648 and Modal (thanks to Sara Kalvala);
   649 
   650 * HOL/Auth: correctness proofs for authentication protocols;
   651 
   652 * HOL: new auto_tac combines rewriting and classical reasoning (many
   653 examples on HOL/Auth);
   654 
   655 * HOL: new command AddIffs for declaring theorems of the form P=Q to
   656 the rewriter and classical reasoner simultaneously;
   657 
   658 * function uresult no longer returns theorems in "standard" format;
   659 regain previous version by: val uresult = standard o uresult;
   660 
   661 
   662 
   663 New in Isabelle94-6
   664 -------------------
   665 
   666 * oracles -- these establish an interface between Isabelle and trusted
   667 external reasoners, which may deliver results as theorems;
   668 
   669 * proof objects (in particular record all uses of oracles);
   670 
   671 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
   672 
   673 * "constdefs" section in theory files;
   674 
   675 * "primrec" section (HOL) no longer requires names;
   676 
   677 * internal type "tactic" now simply "thm -> thm Sequence.seq";
   678 
   679 
   680 
   681 New in Isabelle94-5
   682 -------------------
   683 
   684 * reduced space requirements;
   685 
   686 * automatic HTML generation from theories;
   687 
   688 * theory files no longer require "..." (quotes) around most types;
   689 
   690 * new examples, including two proofs of the Church-Rosser theorem;
   691 
   692 * non-curried (1994) version of HOL is no longer distributed;
   693 
   694 
   695 
   696 New in Isabelle94-4
   697 -------------------
   698 
   699 * greatly reduced space requirements;
   700 
   701 * theory files (.thy) no longer require \...\ escapes at line breaks;
   702 
   703 * searchable theorem database (see the section "Retrieving theorems" on 
   704 page 8 of the Reference Manual);
   705 
   706 * new examples, including Grabczewski's monumental case study of the
   707 Axiom of Choice;
   708 
   709 * The previous version of HOL renamed to Old_HOL;
   710 
   711 * The new version of HOL (previously called CHOL) uses a curried syntax 
   712 for functions.  Application looks like f a b instead of f(a,b);
   713 
   714 * Mutually recursive inductive definitions finally work in HOL;
   715 
   716 * In ZF, pattern-matching on tuples is now available in all abstractions and
   717 translates to the operator "split";
   718 
   719 
   720 
   721 New in Isabelle94-3
   722 -------------------
   723 
   724 * new infix operator, addss, allowing the classical reasoner to 
   725 perform simplification at each step of its search.  Example:
   726 	fast_tac (cs addss ss)
   727 
   728 * a new logic, CHOL, the same as HOL, but with a curried syntax 
   729 for functions.  Application looks like f a b instead of f(a,b).  Also pairs 
   730 look like (a,b) instead of <a,b>;
   731 
   732 * PLEASE NOTE: CHOL will eventually replace HOL!
   733 
   734 * In CHOL, pattern-matching on tuples is now available in all abstractions.
   735 It translates to the operator "split".  A new theory of integers is available;
   736 
   737 * In ZF, integer numerals now denote two's-complement binary integers.
   738 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
   739 
   740 * Many new examples: I/O automata, Church-Rosser theorem, equivalents 
   741 of the Axiom of Choice;
   742 
   743 
   744 
   745 New in Isabelle94-2
   746 -------------------
   747 
   748 * Significantly faster resolution;  
   749 
   750 * the different sections in a .thy file can now be mixed and repeated
   751 freely;
   752 
   753 * Database of theorems for FOL, HOL and ZF.  New
   754 commands including qed, qed_goal and bind_thm store theorems in the database.
   755 
   756 * Simple database queries: return a named theorem (get_thm) or all theorems of
   757 a given theory (thms_of), or find out what theory a theorem was proved in
   758 (theory_of_thm);
   759 
   760 * Bugs fixed in the inductive definition and datatype packages;
   761 
   762 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
   763 and HOL_dup_cs obsolete;
   764 
   765 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
   766 have been removed;
   767 
   768 * Simpler definition of function space in ZF;
   769 
   770 * new results about cardinal and ordinal arithmetic in ZF;
   771 
   772 * 'subtype' facility in HOL for introducing new types as subsets of existing
   773 types;
   774 
   775 
   776 $Id$