NEWS
author paulson
Thu Aug 13 17:28:19 1998 +0200 (1998-08-13)
changeset 5308 3ca4da83012c
parent 5282 80c75c862a8f
child 5332 cd53e59688a8
permissions -rw-r--r--
stac
     1 Isabelle NEWS -- history of user-visible changes
     2 ================================================
     3 
     4 New in this Isabelle version
     5 ----------------------------
     6 
     7 *** Overview of INCOMPATIBILITIES (see below for more details) ***
     8 
     9 * several changes of proof tools;
    10 
    11 * HOL: major changes to the inductive and datatype packages;
    12 
    13 * HOL: renamed r^-1 to 'converse' from 'inverse'; `inj_onto' is now
    14 called `inj_on';
    15 
    16 * HOL: removed duplicate thms in Arith:
    17   less_imp_add_less  should be replaced by  trans_less_add1
    18   le_imp_add_le      should be replaced by  trans_le_add1
    19 
    20 *** Proof tools ***
    21 
    22 * Simplifier: Asm_full_simp_tac is now more aggressive.
    23   1. It will sometimes reorient premises if that increases their power to
    24      simplify.
    25   2. It does no longer proceed strictly from left to right but may also
    26      rotate premises to achieve further simplification.
    27   For compatibility reasons there is now Asm_lr_simp_tac which is like the
    28   old Asm_full_simp_tac in that it does not rotate premises.
    29 
    30 * Classical reasoner: wrapper mechanism for the classical reasoner now
    31 allows for selected deletion of wrappers, by introduction of names for
    32 wrapper functionals.  This implies that addbefore, addSbefore,
    33 addaltern, and addSaltern now take a pair (name, tactic) as argument,
    34 and that adding two tactics with the same name overwrites the first
    35 one (emitting a warning).
    36   type wrapper = (int -> tactic) -> (int -> tactic)
    37   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
    38   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
    39   delWrapper, delSWrapper: claset *  string            -> claset
    40   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
    41 
    42 * HOL/split_all_tac is now much faster and fails if there is nothing
    43 to split.  Existing (fragile) proofs may require adaption because the
    44 order and the names of the automatically generated variables have
    45 changed.  split_all_tac has moved within claset() from unsafe wrappers
    46 to safe wrappers, which means that !!-bound variables are split much
    47 more aggressively, and safe_tac and clarify_tac now split such
    48 variables.  If this splitting is not appropriate, use delSWrapper
    49 "split_all_tac".
    50 
    51 * HOL/Simplifier:
    52 
    53  - Rewrite rules for case distinctions can now be added permanently to
    54    the default simpset using Addsplits just like Addsimps. They can be
    55    removed via Delsplits just like Delsimps. Lower-case versions are
    56    also available.
    57 
    58  - The rule split_if is now part of the default simpset. This means
    59    that the simplifier will eliminate all occurrences of if-then-else
    60    in the conclusion of a goal. To prevent this, you can either remove
    61    split_if completely from the default simpset by `Delsplits
    62    [split_if]' or remove it in a specific call of the simplifier using
    63    `... delsplits [split_if]'.  You can also add/delete other case
    64    splitting rules to/from the default simpset: every datatype
    65    generates suitable rules `split_t_case' and `split_t_case_asm'
    66    (where t is the name of the datatype).
    67 
    68 * Classical reasoner - Simplifier combination: new force_tac (and
    69 derivatives Force_tac, force) combines rewriting and classical
    70 reasoning (and whatever other tools) similarly to auto_tac, but is
    71 aimed to solve the given subgoal completely;
    72 
    73 
    74 *** General ***
    75 
    76 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
    77 and `goalw': the theory is no longer needed as an explicit argument -
    78 the current theory context is used; assumptions are no longer returned
    79 at the ML-level unless one of them starts with ==> or !!; it is
    80 recommended to convert to these new commands using isatool fixgoal
    81 (backup your sources first!);
    82 
    83 * new top-level commands 'thm' and 'thms' for retrieving theorems from
    84 the current theory context, and 'theory' to lookup stored theories;
    85 
    86 * new theory section 'nonterminals' for purely syntactic types;
    87 
    88 * new theory section 'setup' for generic ML setup functions
    89 (e.g. package initialization);
    90 
    91 * the distribution now includes Isabelle icons: see
    92 lib/logo/isabelle-{small,tiny}.xpm;
    93 
    94 
    95 *** HOL ***
    96 
    97 * HOL/inductive package reorganized and improved: now supports mutual
    98 definitions such as
    99 
   100   inductive EVEN ODD
   101     intrs
   102       null "0 : EVEN"
   103       oddI "n : EVEN ==> Suc n : ODD"
   104       evenI "n : ODD ==> Suc n : EVEN"
   105 
   106 new theorem list "elims" contains an elimination rule for each of the
   107 recursive sets; inductive definitions now handle disjunctive premises
   108 correctly (also ZF);
   109 
   110 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   111 "mutual_induct" no longer exists - the induction rule is always
   112 contained in "induct";
   113 
   114 
   115 * HOL/datatype package re-implemented and greatly improved: now
   116 supports mutually recursive datatypes such as
   117 
   118   datatype
   119     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
   120             | SUM ('a aexp) ('a aexp)
   121             | DIFF ('a aexp) ('a aexp)
   122             | NUM 'a
   123   and
   124     'a bexp = LESS ('a aexp) ('a aexp)
   125             | AND ('a bexp) ('a bexp)
   126             | OR ('a bexp) ('a bexp)
   127 
   128 as well as indirectly recursive datatypes such as
   129 
   130   datatype
   131     ('a, 'b) term = Var 'a
   132                   | App 'b ((('a, 'b) term) list)
   133 
   134 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
   135 induction on mutually / indirectly recursive datatypes.
   136 
   137 Primrec equations are now stored in theory and can be accessed via
   138 <function_name>.simps.
   139 
   140 INCOMPATIBILITIES:
   141 
   142   - Theories using datatypes must now have theory Datatype as an
   143     ancestor.
   144   - The specific <typename>.induct_tac no longer exists - use the
   145     generic induct_tac instead.
   146   - natE has been renamed to nat.exhaust - use exhaust_tac
   147     instead of res_inst_tac ... natE. Note that the variable
   148     names in nat.exhaust differ from the names in natE, this
   149     may cause some "fragile" proofs to fail.
   150   - The theorems split_<typename>_case and split_<typename>_case_asm
   151     have been renamed to <typename>.split and <typename>.split_asm.
   152   - Since default sorts of type variables are now handled correctly,
   153     some datatype definitions may have to be annotated with explicit
   154     sort constraints.
   155   - Primrec definitions no longer require function name and type
   156     of recursive argument.
   157 
   158 Consider using isatool fixdatatype to adapt your theories and proof
   159 scripts to the new package (backup your sources first!).
   160 
   161 
   162 * HOL/record package: now includes concrete syntax for record types,
   163 terms, updates; still lacks important theorems, like surjective
   164 pairing and split;
   165 
   166 * reorganized the main HOL image: HOL/Integ and String loaded by
   167 default; theory Main includes everything;
   168 
   169 * added option_map_eq_Some to the default simpset claset;
   170 
   171 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
   172 
   173 * many new identities for unions, intersections, set difference, etc.;
   174 
   175 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
   176 called split_if, split_split, split_sum_case and split_nat_case (to go
   177 with add/delsplits);
   178 
   179 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
   180 (?x::unit) = (); this is made part of the default simpset, which COULD
   181 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
   182 'Delsimprocs [unit_eq_proc];' as last resort); also note that
   183 unit_abs_eta_conv is added in order to counter the effect of
   184 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
   185 %u.f();
   186 
   187 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
   188 makes more sense);
   189 
   190 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now called `equals0E' (the old name was misleading);
   191 
   192 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
   193 to 'converse' from 'inverse' (for compatibility with ZF and some
   194 literature);
   195 
   196 * HOL/recdef can now declare non-recursive functions, with {} supplied as
   197 the well-founded relation;
   198 
   199 * HOL/Update: new theory of function updates:
   200     f(a:=b) == %x. if x=a then b else f x
   201 may also be iterated as in f(a:=b,c:=d,...);
   202 
   203 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
   204 
   205 * HOL/List:
   206   - new function list_update written xs[i:=v] that updates the i-th
   207     list position. May also be iterated as in xs[i:=a,j:=b,...].
   208   - new lexicographic orderings and corresponding wellfoundedness theorems.
   209 
   210 * HOL/Arith:
   211   - removed 'pred' (predecessor) function;
   212   - generalized some theorems about n-1;
   213   - many new laws about "div" and "mod";
   214   - new laws about greatest common divisors (see theory ex/Primes);
   215 
   216 * HOL/Relation: renamed the relational operator r^-1 "converse"
   217 instead of "inverse";
   218 
   219 * directory HOL/Real: a construction of the reals using Dedekind cuts
   220 (not included by default);
   221 
   222 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
   223 
   224 * calling (stac rew i) now fails if "rew" has no effect on the goal
   225   [previously, this check worked only if the rewrite rule was unconditional]
   226   Now rew can involve either definitions or equalities (either == or =).
   227 
   228 *** ZF ***
   229 
   230 * theory Main includes everything;
   231 
   232 * ZF INCOMPATIBILITY: rule `equals0D' is now called `equals0E' (the old name
   233   was misleading).  The rule and 'sym RS equals0E' are now in the default
   234   claset, giving automatic disjointness reasoning but breaking a few old 
   235   proofs.
   236 
   237 * ZF/Update: new theory of function updates
   238     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
   239   may also be iterated as in f(a:=b,c:=d,...);
   240 
   241 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
   242 
   243 * calling (stac rew i) now fails if "rew" has no effect on the goal
   244   [previously, this check worked only if the rewrite rule was unconditional]
   245   Now rew can involve either definitions or equalities (either == or =).
   246 
   247 * case_tac provided for compatibility with HOL
   248     (like the old excluded_middle_tac, but with subgoals swapped)
   249 
   250 
   251 *** Internal programming interfaces ***
   252 
   253 * Pure: several new basic modules made available for general use, see
   254 also src/Pure/README;
   255 
   256 * improved the theory data mechanism to support encapsulation (data
   257 kind name replaced by private Object.kind, acting as authorization
   258 key); new type-safe user interface via functor TheoryDataFun;
   259 
   260 * removed global_names compatibility flag -- all theory declarations
   261 are qualified by default;
   262 
   263 * module Pure/Syntax now offers quote / antiquote translation
   264 functions (useful for Hoare logic etc. with implicit dependencies);
   265 
   266 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
   267 cterm -> thm;
   268 
   269 * new tactical CHANGED_GOAL for checking that a tactic modifies a
   270 subgoal;
   271 
   272 * Display.print_goals function moved to Locale.print_goals;
   273 
   274 
   275 
   276 New in Isabelle98 (January 1998)
   277 --------------------------------
   278 
   279 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   280 
   281 * changed lexical syntax of terms / types: dots made part of long
   282 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
   283 
   284 * simpset (and claset) reference variable replaced by functions
   285 simpset / simpset_ref;
   286 
   287 * no longer supports theory aliases (via merge) and non-trivial
   288 implicit merge of thms' signatures;
   289 
   290 * most internal names of constants changed due to qualified names;
   291 
   292 * changed Pure/Sequence interface (see Pure/seq.ML);
   293 
   294 
   295 *** General Changes ***
   296 
   297 * hierachically structured name spaces (for consts, types, axms, thms
   298 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
   299 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
   300 isatool fixdots ensures space after dots (e.g. "%x. x"); set
   301 long_names for fully qualified output names; NOTE: ML programs
   302 (special tactics, packages etc.) referring to internal names may have
   303 to be adapted to cope with fully qualified names; in case of severe
   304 backward campatibility problems try setting 'global_names' at compile
   305 time to have enrything declared within a flat name space; one may also
   306 fine tune name declarations in theories via the 'global' and 'local'
   307 section;
   308 
   309 * reimplemented the implicit simpset and claset using the new anytype
   310 data filed in signatures; references simpset:simpset ref etc. are
   311 replaced by functions simpset:unit->simpset and
   312 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
   313 to patch your ML files accordingly;
   314 
   315 * HTML output now includes theory graph data for display with Java
   316 applet or isatool browser; data generated automatically via isatool
   317 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
   318 
   319 * defs may now be conditional; improved rewrite_goals_tac to handle
   320 conditional equations;
   321 
   322 * defs now admits additional type arguments, using TYPE('a) syntax;
   323 
   324 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
   325 creates a new theory node; implicit merge of thms' signatures is
   326 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
   327 transfer:theory->thm->thm in (rare) cases;
   328 
   329 * improved handling of draft signatures / theories; draft thms (and
   330 ctyps, cterms) are automatically promoted to real ones;
   331 
   332 * slightly changed interfaces for oracles: admit many per theory, named
   333 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
   334 
   335 * print_goals: optional output of const types (set show_consts and
   336 show_types);
   337 
   338 * improved output of warnings (###) and errors (***);
   339 
   340 * subgoal_tac displays a warning if the new subgoal has type variables;
   341 
   342 * removed old README and Makefiles;
   343 
   344 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
   345 
   346 * removed obsolete init_pps and init_database;
   347 
   348 * deleted the obsolete tactical STATE, which was declared by
   349     fun STATE tacfun st = tacfun st st;
   350 
   351 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
   352 (which abbreviates $HOME);
   353 
   354 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
   355 use isatool fixseq to adapt your ML programs (this works for fully
   356 qualified references to the Sequence structure only!);
   357 
   358 * use_thy no longer requires writable current directory; it always
   359 reloads .ML *and* .thy file, if either one is out of date;
   360 
   361 
   362 *** Classical Reasoner ***
   363 
   364 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
   365 tactics that use classical reasoning to simplify a subgoal without
   366 splitting it into several subgoals;
   367 
   368 * Safe_tac: like safe_tac but uses the default claset;
   369 
   370 
   371 *** Simplifier ***
   372 
   373 * added simplification meta rules:
   374     (asm_)(full_)simplify: simpset -> thm -> thm;
   375 
   376 * simplifier.ML no longer part of Pure -- has to be loaded by object
   377 logics (again);
   378 
   379 * added prems argument to simplification procedures;
   380 
   381 * HOL, FOL, ZF: added infix function `addsplits':
   382   instead of `<simpset> setloop (split_tac <thms>)'
   383   you can simply write `<simpset> addsplits <thms>'
   384 
   385 
   386 *** Syntax ***
   387 
   388 * TYPE('a) syntax for type reflection terms;
   389 
   390 * no longer handles consts with name "" -- declare as 'syntax' instead;
   391 
   392 * pretty printer: changed order of mixfix annotation preference (again!);
   393 
   394 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
   395 
   396 
   397 *** HOL ***
   398 
   399 * HOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   400   with `addloop' of the simplifier to faciliate case splitting in premises.
   401 
   402 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
   403 
   404 * HOL/Auth: new protocol proofs including some for the Internet
   405   protocol TLS;
   406 
   407 * HOL/Map: new theory of `maps' a la VDM;
   408 
   409 * HOL/simplifier: simplification procedures nat_cancel_sums for
   410 cancelling out common nat summands from =, <, <= (in)equalities, or
   411 differences; simplification procedures nat_cancel_factor for
   412 cancelling common factor from =, <, <= (in)equalities over natural
   413 sums; nat_cancel contains both kinds of procedures, it is installed by
   414 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
   415 
   416 * HOL/simplifier: terms of the form
   417   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
   418   are rewritten to
   419   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
   420   and those of the form
   421   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
   422   are rewritten to
   423   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
   424 
   425 * HOL/datatype
   426   Each datatype `t' now comes with a theorem `split_t_case' of the form
   427 
   428   P(t_case f1 ... fn x) =
   429      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
   430         ...
   431        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
   432      )
   433 
   434   and a theorem `split_t_case_asm' of the form
   435 
   436   P(t_case f1 ... fn x) =
   437     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
   438         ...
   439        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
   440      )
   441   which can be added to a simpset via `addsplits'. The existing theorems
   442   expand_list_case and expand_option_case have been renamed to
   443   split_list_case and split_option_case.
   444 
   445 * HOL/Arithmetic:
   446   - `pred n' is automatically converted to `n-1'.
   447     Users are strongly encouraged not to use `pred' any longer,
   448     because it will disappear altogether at some point.
   449   - Users are strongly encouraged to write "0 < n" rather than
   450     "n ~= 0". Theorems and proof tools have been modified towards this
   451     `standard'.
   452 
   453 * HOL/Lists:
   454   the function "set_of_list" has been renamed "set" (and its theorems too);
   455   the function "nth" now takes its arguments in the reverse order and
   456   has acquired the infix notation "!" as in "xs!n".
   457 
   458 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
   459 
   460 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
   461   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
   462 
   463 * HOL/record: extensible records with schematic structural subtyping
   464 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
   465 still lacks various theorems and concrete record syntax;
   466 
   467 
   468 *** HOLCF ***
   469 
   470 * removed "axioms" and "generated by" sections;
   471 
   472 * replaced "ops" section by extended "consts" section, which is capable of
   473   handling the continuous function space "->" directly;
   474 
   475 * domain package:
   476   . proves theorems immediately and stores them in the theory,
   477   . creates hierachical name space,
   478   . now uses normal mixfix annotations (instead of cinfix...),
   479   . minor changes to some names and values (for consistency),
   480   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
   481   . separator between mutual domain defs: changed "," to "and",
   482   . improved handling of sort constraints;  now they have to
   483     appear on the left-hand side of the equations only;
   484 
   485 * fixed LAM <x,y,zs>.b syntax;
   486 
   487 * added extended adm_tac to simplifier in HOLCF -- can now discharge
   488 adm (%x. P (t x)), where P is chainfinite and t continuous;
   489 
   490 
   491 *** FOL and ZF ***
   492 
   493 * FOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   494   with `addloop' of the simplifier to faciliate case splitting in premises.
   495 
   496 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
   497 in HOL, they strip ALL and --> from proved theorems;
   498 
   499 
   500 
   501 New in Isabelle94-8 (May 1997)
   502 ------------------------------
   503 
   504 *** General Changes ***
   505 
   506 * new utilities to build / run / maintain Isabelle etc. (in parts
   507 still somewhat experimental); old Makefiles etc. still functional;
   508 
   509 * new 'Isabelle System Manual';
   510 
   511 * INSTALL text, together with ./configure and ./build scripts;
   512 
   513 * reimplemented type inference for greater efficiency, better error
   514 messages and clean internal interface;
   515 
   516 * prlim command for dealing with lots of subgoals (an easier way of
   517 setting goals_limit);
   518 
   519 
   520 *** Syntax ***
   521 
   522 * supports alternative (named) syntax tables (parser and pretty
   523 printer); internal interface is provided by add_modesyntax(_i);
   524 
   525 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
   526 be used in conjunction with the Isabelle symbol font; uses the
   527 "symbols" syntax table;
   528 
   529 * added token_translation interface (may translate name tokens in
   530 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
   531 the current print_mode); IMPORTANT: user print translation functions
   532 are responsible for marking newly introduced bounds
   533 (Syntax.mark_boundT);
   534 
   535 * token translations for modes "xterm" and "xterm_color" that display
   536 names in bold, underline etc. or colors (which requires a color
   537 version of xterm);
   538 
   539 * infixes may now be declared with names independent of their syntax;
   540 
   541 * added typed_print_translation (like print_translation, but may
   542 access type of constant);
   543 
   544 
   545 *** Classical Reasoner ***
   546 
   547 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
   548 some limitations.  Blast_tac...
   549   + ignores addss, addbefore, addafter; this restriction is intrinsic
   550   + ignores elimination rules that don't have the correct format
   551 	(the conclusion MUST be a formula variable)
   552   + ignores types, which can make HOL proofs fail
   553   + rules must not require higher-order unification, e.g. apply_type in ZF
   554     [message "Function Var's argument not a bound variable" relates to this]
   555   + its proof strategy is more general but can actually be slower
   556 
   557 * substitution with equality assumptions no longer permutes other
   558 assumptions;
   559 
   560 * minor changes in semantics of addafter (now called addaltern); renamed
   561 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
   562 (and access functions for it);
   563 
   564 * improved combination of classical reasoner and simplifier: 
   565   + functions for handling clasimpsets
   566   + improvement of addss: now the simplifier is called _after_ the
   567     safe steps.
   568   + safe variant of addss called addSss: uses safe simplifications
   569     _during_ the safe steps. It is more complete as it allows multiple 
   570     instantiations of unknowns (e.g. with slow_tac).
   571 
   572 *** Simplifier ***
   573 
   574 * added interface for simplification procedures (functions that
   575 produce *proven* rewrite rules on the fly, depending on current
   576 redex);
   577 
   578 * ordering on terms as parameter (used for ordered rewriting);
   579 
   580 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
   581 
   582 * the solver is now split into a safe and an unsafe part.
   583 This should be invisible for the normal user, except that the
   584 functions setsolver and addsolver have been renamed to setSolver and
   585 addSolver; added safe_asm_full_simp_tac;
   586 
   587 
   588 *** HOL ***
   589 
   590 * a generic induction tactic `induct_tac' which works for all datatypes and
   591 also for type `nat';
   592 
   593 * a generic case distinction tactic `exhaust_tac' which works for all
   594 datatypes and also for type `nat';
   595 
   596 * each datatype comes with a function `size';
   597 
   598 * patterns in case expressions allow tuple patterns as arguments to
   599 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
   600 
   601 * primrec now also works with type nat;
   602 
   603 * recdef: a new declaration form, allows general recursive functions to be
   604 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
   605 
   606 * the constant for negation has been renamed from "not" to "Not" to
   607 harmonize with FOL, ZF, LK, etc.;
   608 
   609 * HOL/ex/LFilter theory of a corecursive "filter" functional for
   610 infinite lists;
   611 
   612 * HOL/Modelcheck demonstrates invocation of model checker oracle;
   613 
   614 * HOL/ex/Ring.thy declares cring_simp, which solves equational
   615 problems in commutative rings, using axiomatic type classes for + and *;
   616 
   617 * more examples in HOL/MiniML and HOL/Auth;
   618 
   619 * more default rewrite rules for quantifiers, union/intersection;
   620 
   621 * a new constant `arbitrary == @x.False';
   622 
   623 * HOLCF/IOA replaces old HOL/IOA;
   624 
   625 * HOLCF changes: derived all rules and arities 
   626   + axiomatic type classes instead of classes 
   627   + typedef instead of faking type definitions
   628   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
   629   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
   630   + eliminated the types void, one, tr
   631   + use unit lift and bool lift (with translations) instead of one and tr
   632   + eliminated blift from Lift3.thy (use Def instead of blift)
   633   all eliminated rules are derived as theorems --> no visible changes ;
   634 
   635 
   636 *** ZF ***
   637 
   638 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
   639 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
   640 as ZF_cs addSIs [equalityI];
   641 
   642 
   643 
   644 New in Isabelle94-7 (November 96)
   645 ---------------------------------
   646 
   647 * allowing negative levels (as offsets) in prlev and choplev;
   648 
   649 * super-linear speedup for large simplifications;
   650 
   651 * FOL, ZF and HOL now use miniscoping: rewriting pushes
   652 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
   653 FAIL); can suppress it using the command Delsimps (ex_simps @
   654 all_simps); De Morgan laws are also now included, by default;
   655 
   656 * improved printing of ==>  :  ~:
   657 
   658 * new object-logic "Sequents" adds linear logic, while replacing LK
   659 and Modal (thanks to Sara Kalvala);
   660 
   661 * HOL/Auth: correctness proofs for authentication protocols;
   662 
   663 * HOL: new auto_tac combines rewriting and classical reasoning (many
   664 examples on HOL/Auth);
   665 
   666 * HOL: new command AddIffs for declaring theorems of the form P=Q to
   667 the rewriter and classical reasoner simultaneously;
   668 
   669 * function uresult no longer returns theorems in "standard" format;
   670 regain previous version by: val uresult = standard o uresult;
   671 
   672 
   673 
   674 New in Isabelle94-6
   675 -------------------
   676 
   677 * oracles -- these establish an interface between Isabelle and trusted
   678 external reasoners, which may deliver results as theorems;
   679 
   680 * proof objects (in particular record all uses of oracles);
   681 
   682 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
   683 
   684 * "constdefs" section in theory files;
   685 
   686 * "primrec" section (HOL) no longer requires names;
   687 
   688 * internal type "tactic" now simply "thm -> thm Sequence.seq";
   689 
   690 
   691 
   692 New in Isabelle94-5
   693 -------------------
   694 
   695 * reduced space requirements;
   696 
   697 * automatic HTML generation from theories;
   698 
   699 * theory files no longer require "..." (quotes) around most types;
   700 
   701 * new examples, including two proofs of the Church-Rosser theorem;
   702 
   703 * non-curried (1994) version of HOL is no longer distributed;
   704 
   705 
   706 
   707 New in Isabelle94-4
   708 -------------------
   709 
   710 * greatly reduced space requirements;
   711 
   712 * theory files (.thy) no longer require \...\ escapes at line breaks;
   713 
   714 * searchable theorem database (see the section "Retrieving theorems" on 
   715 page 8 of the Reference Manual);
   716 
   717 * new examples, including Grabczewski's monumental case study of the
   718 Axiom of Choice;
   719 
   720 * The previous version of HOL renamed to Old_HOL;
   721 
   722 * The new version of HOL (previously called CHOL) uses a curried syntax 
   723 for functions.  Application looks like f a b instead of f(a,b);
   724 
   725 * Mutually recursive inductive definitions finally work in HOL;
   726 
   727 * In ZF, pattern-matching on tuples is now available in all abstractions and
   728 translates to the operator "split";
   729 
   730 
   731 
   732 New in Isabelle94-3
   733 -------------------
   734 
   735 * new infix operator, addss, allowing the classical reasoner to 
   736 perform simplification at each step of its search.  Example:
   737 	fast_tac (cs addss ss)
   738 
   739 * a new logic, CHOL, the same as HOL, but with a curried syntax 
   740 for functions.  Application looks like f a b instead of f(a,b).  Also pairs 
   741 look like (a,b) instead of <a,b>;
   742 
   743 * PLEASE NOTE: CHOL will eventually replace HOL!
   744 
   745 * In CHOL, pattern-matching on tuples is now available in all abstractions.
   746 It translates to the operator "split".  A new theory of integers is available;
   747 
   748 * In ZF, integer numerals now denote two's-complement binary integers.
   749 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
   750 
   751 * Many new examples: I/O automata, Church-Rosser theorem, equivalents 
   752 of the Axiom of Choice;
   753 
   754 
   755 
   756 New in Isabelle94-2
   757 -------------------
   758 
   759 * Significantly faster resolution;  
   760 
   761 * the different sections in a .thy file can now be mixed and repeated
   762 freely;
   763 
   764 * Database of theorems for FOL, HOL and ZF.  New
   765 commands including qed, qed_goal and bind_thm store theorems in the database.
   766 
   767 * Simple database queries: return a named theorem (get_thm) or all theorems of
   768 a given theory (thms_of), or find out what theory a theorem was proved in
   769 (theory_of_thm);
   770 
   771 * Bugs fixed in the inductive definition and datatype packages;
   772 
   773 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
   774 and HOL_dup_cs obsolete;
   775 
   776 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
   777 have been removed;
   778 
   779 * Simpler definition of function space in ZF;
   780 
   781 * new results about cardinal and ordinal arithmetic in ZF;
   782 
   783 * 'subtype' facility in HOL for introducing new types as subsets of existing
   784 types;
   785 
   786 
   787 $Id$