NEWS
author wenzelm
Tue Aug 04 18:41:11 1998 +0200 (1998-08-04)
changeset 5251 fee54d5c511c
parent 5226 89934cd022a9
child 5267 41a01176b9de
permissions -rw-r--r--
tuned;
Display.print_goals function moved to Locale.print_goals;
     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.exhaust - use exhaust_tac
   145     instead of res_inst_tac ... natE. Note that the variable
   146     names in nat.exhaust 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 * Pure: several new basic modules made available for general use, see
   245 also src/Pure/README;
   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 * removed global_names compatibility flag -- all theory declarations
   252 are qualified by default;
   253 
   254 * module Pure/Syntax now offers quote / antiquote translation
   255 functions (useful for Hoare logic etc. with implicit dependencies);
   256 
   257 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
   258 cterm -> thm;
   259 
   260 * new tactical CHANGED_GOAL for checking that a tactic modifies a
   261 subgoal;
   262 
   263 * Display.print_goals function moved to Locale.print_goals;
   264 
   265 
   266 
   267 New in Isabelle98 (January 1998)
   268 --------------------------------
   269 
   270 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   271 
   272 * changed lexical syntax of terms / types: dots made part of long
   273 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
   274 
   275 * simpset (and claset) reference variable replaced by functions
   276 simpset / simpset_ref;
   277 
   278 * no longer supports theory aliases (via merge) and non-trivial
   279 implicit merge of thms' signatures;
   280 
   281 * most internal names of constants changed due to qualified names;
   282 
   283 * changed Pure/Sequence interface (see Pure/seq.ML);
   284 
   285 
   286 *** General Changes ***
   287 
   288 * hierachically structured name spaces (for consts, types, axms, thms
   289 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
   290 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
   291 isatool fixdots ensures space after dots (e.g. "%x. x"); set
   292 long_names for fully qualified output names; NOTE: ML programs
   293 (special tactics, packages etc.) referring to internal names may have
   294 to be adapted to cope with fully qualified names; in case of severe
   295 backward campatibility problems try setting 'global_names' at compile
   296 time to have enrything declared within a flat name space; one may also
   297 fine tune name declarations in theories via the 'global' and 'local'
   298 section;
   299 
   300 * reimplemented the implicit simpset and claset using the new anytype
   301 data filed in signatures; references simpset:simpset ref etc. are
   302 replaced by functions simpset:unit->simpset and
   303 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
   304 to patch your ML files accordingly;
   305 
   306 * HTML output now includes theory graph data for display with Java
   307 applet or isatool browser; data generated automatically via isatool
   308 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
   309 
   310 * defs may now be conditional; improved rewrite_goals_tac to handle
   311 conditional equations;
   312 
   313 * defs now admits additional type arguments, using TYPE('a) syntax;
   314 
   315 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
   316 creates a new theory node; implicit merge of thms' signatures is
   317 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
   318 transfer:theory->thm->thm in (rare) cases;
   319 
   320 * improved handling of draft signatures / theories; draft thms (and
   321 ctyps, cterms) are automatically promoted to real ones;
   322 
   323 * slightly changed interfaces for oracles: admit many per theory, named
   324 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
   325 
   326 * print_goals: optional output of const types (set show_consts and
   327 show_types);
   328 
   329 * improved output of warnings (###) and errors (***);
   330 
   331 * subgoal_tac displays a warning if the new subgoal has type variables;
   332 
   333 * removed old README and Makefiles;
   334 
   335 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
   336 
   337 * removed obsolete init_pps and init_database;
   338 
   339 * deleted the obsolete tactical STATE, which was declared by
   340     fun STATE tacfun st = tacfun st st;
   341 
   342 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
   343 (which abbreviates $HOME);
   344 
   345 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
   346 use isatool fixseq to adapt your ML programs (this works for fully
   347 qualified references to the Sequence structure only!);
   348 
   349 * use_thy no longer requires writable current directory; it always
   350 reloads .ML *and* .thy file, if either one is out of date;
   351 
   352 
   353 *** Classical Reasoner ***
   354 
   355 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
   356 tactics that use classical reasoning to simplify a subgoal without
   357 splitting it into several subgoals;
   358 
   359 * Safe_tac: like safe_tac but uses the default claset;
   360 
   361 
   362 *** Simplifier ***
   363 
   364 * added simplification meta rules:
   365     (asm_)(full_)simplify: simpset -> thm -> thm;
   366 
   367 * simplifier.ML no longer part of Pure -- has to be loaded by object
   368 logics (again);
   369 
   370 * added prems argument to simplification procedures;
   371 
   372 * HOL, FOL, ZF: added infix function `addsplits':
   373   instead of `<simpset> setloop (split_tac <thms>)'
   374   you can simply write `<simpset> addsplits <thms>'
   375 
   376 
   377 *** Syntax ***
   378 
   379 * TYPE('a) syntax for type reflection terms;
   380 
   381 * no longer handles consts with name "" -- declare as 'syntax' instead;
   382 
   383 * pretty printer: changed order of mixfix annotation preference (again!);
   384 
   385 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
   386 
   387 
   388 *** HOL ***
   389 
   390 * HOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   391   with `addloop' of the simplifier to faciliate case splitting in premises.
   392 
   393 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
   394 
   395 * HOL/Auth: new protocol proofs including some for the Internet
   396   protocol TLS;
   397 
   398 * HOL/Map: new theory of `maps' a la VDM;
   399 
   400 * HOL/simplifier: simplification procedures nat_cancel_sums for
   401 cancelling out common nat summands from =, <, <= (in)equalities, or
   402 differences; simplification procedures nat_cancel_factor for
   403 cancelling common factor from =, <, <= (in)equalities over natural
   404 sums; nat_cancel contains both kinds of procedures, it is installed by
   405 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
   406 
   407 * HOL/simplifier: terms of the form
   408   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
   409   are rewritten to
   410   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
   411   and those of the form
   412   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
   413   are rewritten to
   414   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
   415 
   416 * HOL/datatype
   417   Each datatype `t' now comes with a theorem `split_t_case' of the form
   418 
   419   P(t_case f1 ... fn x) =
   420      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
   421         ...
   422        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
   423      )
   424 
   425   and a theorem `split_t_case_asm' of the form
   426 
   427   P(t_case f1 ... fn x) =
   428     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
   429         ...
   430        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
   431      )
   432   which can be added to a simpset via `addsplits'. The existing theorems
   433   expand_list_case and expand_option_case have been renamed to
   434   split_list_case and split_option_case.
   435 
   436 * HOL/Arithmetic:
   437   - `pred n' is automatically converted to `n-1'.
   438     Users are strongly encouraged not to use `pred' any longer,
   439     because it will disappear altogether at some point.
   440   - Users are strongly encouraged to write "0 < n" rather than
   441     "n ~= 0". Theorems and proof tools have been modified towards this
   442     `standard'.
   443 
   444 * HOL/Lists:
   445   the function "set_of_list" has been renamed "set" (and its theorems too);
   446   the function "nth" now takes its arguments in the reverse order and
   447   has acquired the infix notation "!" as in "xs!n".
   448 
   449 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
   450 
   451 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
   452   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
   453 
   454 * HOL/record: extensible records with schematic structural subtyping
   455 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
   456 still lacks various theorems and concrete record syntax;
   457 
   458 
   459 *** HOLCF ***
   460 
   461 * removed "axioms" and "generated by" sections;
   462 
   463 * replaced "ops" section by extended "consts" section, which is capable of
   464   handling the continuous function space "->" directly;
   465 
   466 * domain package:
   467   . proves theorems immediately and stores them in the theory,
   468   . creates hierachical name space,
   469   . now uses normal mixfix annotations (instead of cinfix...),
   470   . minor changes to some names and values (for consistency),
   471   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
   472   . separator between mutual domain defs: changed "," to "and",
   473   . improved handling of sort constraints;  now they have to
   474     appear on the left-hand side of the equations only;
   475 
   476 * fixed LAM <x,y,zs>.b syntax;
   477 
   478 * added extended adm_tac to simplifier in HOLCF -- can now discharge
   479 adm (%x. P (t x)), where P is chainfinite and t continuous;
   480 
   481 
   482 *** FOL and ZF ***
   483 
   484 * FOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   485   with `addloop' of the simplifier to faciliate case splitting in premises.
   486 
   487 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
   488 in HOL, they strip ALL and --> from proved theorems;
   489 
   490 
   491 
   492 New in Isabelle94-8 (May 1997)
   493 ------------------------------
   494 
   495 *** General Changes ***
   496 
   497 * new utilities to build / run / maintain Isabelle etc. (in parts
   498 still somewhat experimental); old Makefiles etc. still functional;
   499 
   500 * new 'Isabelle System Manual';
   501 
   502 * INSTALL text, together with ./configure and ./build scripts;
   503 
   504 * reimplemented type inference for greater efficiency, better error
   505 messages and clean internal interface;
   506 
   507 * prlim command for dealing with lots of subgoals (an easier way of
   508 setting goals_limit);
   509 
   510 
   511 *** Syntax ***
   512 
   513 * supports alternative (named) syntax tables (parser and pretty
   514 printer); internal interface is provided by add_modesyntax(_i);
   515 
   516 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
   517 be used in conjunction with the Isabelle symbol font; uses the
   518 "symbols" syntax table;
   519 
   520 * added token_translation interface (may translate name tokens in
   521 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
   522 the current print_mode); IMPORTANT: user print translation functions
   523 are responsible for marking newly introduced bounds
   524 (Syntax.mark_boundT);
   525 
   526 * token translations for modes "xterm" and "xterm_color" that display
   527 names in bold, underline etc. or colors (which requires a color
   528 version of xterm);
   529 
   530 * infixes may now be declared with names independent of their syntax;
   531 
   532 * added typed_print_translation (like print_translation, but may
   533 access type of constant);
   534 
   535 
   536 *** Classical Reasoner ***
   537 
   538 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
   539 some limitations.  Blast_tac...
   540   + ignores addss, addbefore, addafter; this restriction is intrinsic
   541   + ignores elimination rules that don't have the correct format
   542 	(the conclusion MUST be a formula variable)
   543   + ignores types, which can make HOL proofs fail
   544   + rules must not require higher-order unification, e.g. apply_type in ZF
   545     [message "Function Var's argument not a bound variable" relates to this]
   546   + its proof strategy is more general but can actually be slower
   547 
   548 * substitution with equality assumptions no longer permutes other
   549 assumptions;
   550 
   551 * minor changes in semantics of addafter (now called addaltern); renamed
   552 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
   553 (and access functions for it);
   554 
   555 * improved combination of classical reasoner and simplifier: 
   556   + functions for handling clasimpsets
   557   + improvement of addss: now the simplifier is called _after_ the
   558     safe steps.
   559   + safe variant of addss called addSss: uses safe simplifications
   560     _during_ the safe steps. It is more complete as it allows multiple 
   561     instantiations of unknowns (e.g. with slow_tac).
   562 
   563 *** Simplifier ***
   564 
   565 * added interface for simplification procedures (functions that
   566 produce *proven* rewrite rules on the fly, depending on current
   567 redex);
   568 
   569 * ordering on terms as parameter (used for ordered rewriting);
   570 
   571 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
   572 
   573 * the solver is now split into a safe and an unsafe part.
   574 This should be invisible for the normal user, except that the
   575 functions setsolver and addsolver have been renamed to setSolver and
   576 addSolver; added safe_asm_full_simp_tac;
   577 
   578 
   579 *** HOL ***
   580 
   581 * a generic induction tactic `induct_tac' which works for all datatypes and
   582 also for type `nat';
   583 
   584 * a generic case distinction tactic `exhaust_tac' which works for all
   585 datatypes and also for type `nat';
   586 
   587 * each datatype comes with a function `size';
   588 
   589 * patterns in case expressions allow tuple patterns as arguments to
   590 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
   591 
   592 * primrec now also works with type nat;
   593 
   594 * recdef: a new declaration form, allows general recursive functions to be
   595 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
   596 
   597 * the constant for negation has been renamed from "not" to "Not" to
   598 harmonize with FOL, ZF, LK, etc.;
   599 
   600 * HOL/ex/LFilter theory of a corecursive "filter" functional for
   601 infinite lists;
   602 
   603 * HOL/Modelcheck demonstrates invocation of model checker oracle;
   604 
   605 * HOL/ex/Ring.thy declares cring_simp, which solves equational
   606 problems in commutative rings, using axiomatic type classes for + and *;
   607 
   608 * more examples in HOL/MiniML and HOL/Auth;
   609 
   610 * more default rewrite rules for quantifiers, union/intersection;
   611 
   612 * a new constant `arbitrary == @x.False';
   613 
   614 * HOLCF/IOA replaces old HOL/IOA;
   615 
   616 * HOLCF changes: derived all rules and arities 
   617   + axiomatic type classes instead of classes 
   618   + typedef instead of faking type definitions
   619   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
   620   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
   621   + eliminated the types void, one, tr
   622   + use unit lift and bool lift (with translations) instead of one and tr
   623   + eliminated blift from Lift3.thy (use Def instead of blift)
   624   all eliminated rules are derived as theorems --> no visible changes ;
   625 
   626 
   627 *** ZF ***
   628 
   629 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
   630 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
   631 as ZF_cs addSIs [equalityI];
   632 
   633 
   634 
   635 New in Isabelle94-7 (November 96)
   636 ---------------------------------
   637 
   638 * allowing negative levels (as offsets) in prlev and choplev;
   639 
   640 * super-linear speedup for large simplifications;
   641 
   642 * FOL, ZF and HOL now use miniscoping: rewriting pushes
   643 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
   644 FAIL); can suppress it using the command Delsimps (ex_simps @
   645 all_simps); De Morgan laws are also now included, by default;
   646 
   647 * improved printing of ==>  :  ~:
   648 
   649 * new object-logic "Sequents" adds linear logic, while replacing LK
   650 and Modal (thanks to Sara Kalvala);
   651 
   652 * HOL/Auth: correctness proofs for authentication protocols;
   653 
   654 * HOL: new auto_tac combines rewriting and classical reasoning (many
   655 examples on HOL/Auth);
   656 
   657 * HOL: new command AddIffs for declaring theorems of the form P=Q to
   658 the rewriter and classical reasoner simultaneously;
   659 
   660 * function uresult no longer returns theorems in "standard" format;
   661 regain previous version by: val uresult = standard o uresult;
   662 
   663 
   664 
   665 New in Isabelle94-6
   666 -------------------
   667 
   668 * oracles -- these establish an interface between Isabelle and trusted
   669 external reasoners, which may deliver results as theorems;
   670 
   671 * proof objects (in particular record all uses of oracles);
   672 
   673 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
   674 
   675 * "constdefs" section in theory files;
   676 
   677 * "primrec" section (HOL) no longer requires names;
   678 
   679 * internal type "tactic" now simply "thm -> thm Sequence.seq";
   680 
   681 
   682 
   683 New in Isabelle94-5
   684 -------------------
   685 
   686 * reduced space requirements;
   687 
   688 * automatic HTML generation from theories;
   689 
   690 * theory files no longer require "..." (quotes) around most types;
   691 
   692 * new examples, including two proofs of the Church-Rosser theorem;
   693 
   694 * non-curried (1994) version of HOL is no longer distributed;
   695 
   696 
   697 
   698 New in Isabelle94-4
   699 -------------------
   700 
   701 * greatly reduced space requirements;
   702 
   703 * theory files (.thy) no longer require \...\ escapes at line breaks;
   704 
   705 * searchable theorem database (see the section "Retrieving theorems" on 
   706 page 8 of the Reference Manual);
   707 
   708 * new examples, including Grabczewski's monumental case study of the
   709 Axiom of Choice;
   710 
   711 * The previous version of HOL renamed to Old_HOL;
   712 
   713 * The new version of HOL (previously called CHOL) uses a curried syntax 
   714 for functions.  Application looks like f a b instead of f(a,b);
   715 
   716 * Mutually recursive inductive definitions finally work in HOL;
   717 
   718 * In ZF, pattern-matching on tuples is now available in all abstractions and
   719 translates to the operator "split";
   720 
   721 
   722 
   723 New in Isabelle94-3
   724 -------------------
   725 
   726 * new infix operator, addss, allowing the classical reasoner to 
   727 perform simplification at each step of its search.  Example:
   728 	fast_tac (cs addss ss)
   729 
   730 * a new logic, CHOL, the same as HOL, but with a curried syntax 
   731 for functions.  Application looks like f a b instead of f(a,b).  Also pairs 
   732 look like (a,b) instead of <a,b>;
   733 
   734 * PLEASE NOTE: CHOL will eventually replace HOL!
   735 
   736 * In CHOL, pattern-matching on tuples is now available in all abstractions.
   737 It translates to the operator "split".  A new theory of integers is available;
   738 
   739 * In ZF, integer numerals now denote two's-complement binary integers.
   740 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
   741 
   742 * Many new examples: I/O automata, Church-Rosser theorem, equivalents 
   743 of the Axiom of Choice;
   744 
   745 
   746 
   747 New in Isabelle94-2
   748 -------------------
   749 
   750 * Significantly faster resolution;  
   751 
   752 * the different sections in a .thy file can now be mixed and repeated
   753 freely;
   754 
   755 * Database of theorems for FOL, HOL and ZF.  New
   756 commands including qed, qed_goal and bind_thm store theorems in the database.
   757 
   758 * Simple database queries: return a named theorem (get_thm) or all theorems of
   759 a given theory (thms_of), or find out what theory a theorem was proved in
   760 (theory_of_thm);
   761 
   762 * Bugs fixed in the inductive definition and datatype packages;
   763 
   764 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
   765 and HOL_dup_cs obsolete;
   766 
   767 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
   768 have been removed;
   769 
   770 * Simpler definition of function space in ZF;
   771 
   772 * new results about cardinal and ordinal arithmetic in ZF;
   773 
   774 * 'subtype' facility in HOL for introducing new types as subsets of existing
   775 types;
   776 
   777 
   778 $Id$