NEWS
author paulson
Thu Oct 15 12:15:14 1998 +0200 (1998-10-15)
changeset 5650 38bda28c68a2
parent 5572 53c6ea1e6d94
child 5651 ca45d6126c8a
permissions -rw-r--r--
integer simprocs
     1 
     2 Isabelle NEWS -- history user-relevant 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: new version of inductive and datatype;
    13 
    14 * HOL: major changes to the inductive and datatype packages;
    15 
    16 * HOL: renamed r^-1 to 'converse' from 'inverse'; `inj_onto' is now
    17 called `inj_on';
    18 
    19 * HOL: removed duplicate thms in Arith:
    20   less_imp_add_less  should be replaced by  trans_less_add1
    21   le_imp_add_le      should be replaced by  trans_le_add1
    22 
    23 * HOL: unary - is now overloaded (new type constraints may be required);
    24 
    25 * HOL and ZF: unary minus for integers is now #- instead of #~.  In ZF, 
    26   expressions such as n#-1 must be changed to n#- 1, since #-1 is now taken
    27   as an integer constant.
    28 
    29 * Pure: ML function 'theory_of' replaced by 'theory';
    30 
    31 
    32 *** Proof tools ***
    33 
    34 * Simplifier: Asm_full_simp_tac is now more aggressive.
    35   1. It will sometimes reorient premises if that increases their power to
    36      simplify.
    37   2. It does no longer proceed strictly from left to right but may also
    38      rotate premises to achieve further simplification.
    39   For compatibility reasons there is now Asm_lr_simp_tac which is like the
    40   old Asm_full_simp_tac in that it does not rotate premises.
    41 
    42 * Classical reasoner: wrapper mechanism for the classical reasoner now
    43 allows for selected deletion of wrappers, by introduction of names for
    44 wrapper functionals.  This implies that addbefore, addSbefore,
    45 addaltern, and addSaltern now take a pair (name, tactic) as argument,
    46 and that adding two tactics with the same name overwrites the first
    47 one (emitting a warning).
    48   type wrapper = (int -> tactic) -> (int -> tactic)
    49   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
    50   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
    51   delWrapper, delSWrapper: claset *  string            -> claset
    52   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
    53 
    54 * Classical reasoner: addbefore / addSbefore now have APPEND / ORELSE semantics;
    55   addbefore now affects only the unsafe part of step_tac etc.;
    56   This affects addss/auto_tac/force_tac, so EXISTING (INSTABLE) PROOFS MAY FAIL, but
    57   most proofs should be fixable easily, e.g. by replacing Auto_tac by Force_tac.
    58 
    59 * Classical reasoner: setwrapper to setWrapper and compwrapper to compWrapper; 
    60   added safe wrapper (and access functions for it);
    61 
    62 * HOL/split_all_tac is now much faster and fails if there is nothing
    63 to split.  Existing (fragile) proofs may require adaption because the
    64 order and the names of the automatically generated variables have
    65 changed.  split_all_tac has moved within claset() from unsafe wrappers
    66 to safe wrappers, which means that !!-bound variables are split much
    67 more aggressively, and safe_tac and clarify_tac now split such
    68 variables.  If this splitting is not appropriate, use delSWrapper
    69 "split_all_tac".
    70 
    71 * HOL/Simplifier:
    72 
    73  - Rewrite rules for case distinctions can now be added permanently to
    74    the default simpset using Addsplits just like Addsimps. They can be
    75    removed via Delsplits just like Delsimps. Lower-case versions are
    76    also available.
    77 
    78  - The rule split_if is now part of the default simpset. This means
    79    that the simplifier will eliminate all occurrences of if-then-else
    80    in the conclusion of a goal. To prevent this, you can either remove
    81    split_if completely from the default simpset by `Delsplits
    82    [split_if]' or remove it in a specific call of the simplifier using
    83    `... delsplits [split_if]'.  You can also add/delete other case
    84    splitting rules to/from the default simpset: every datatype
    85    generates suitable rules `split_t_case' and `split_t_case_asm'
    86    (where t is the name of the datatype).
    87 
    88 * Classical reasoner - Simplifier combination: new force_tac (and
    89 derivatives Force_tac, force) combines rewriting and classical
    90 reasoning (and whatever other tools) similarly to auto_tac, but is
    91 aimed to solve the given subgoal completely;
    92 
    93 
    94 *** General ***
    95 
    96 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
    97 and `goalw': the theory is no longer needed as an explicit argument -
    98 the current theory context is used; assumptions are no longer returned
    99 at the ML-level unless one of them starts with ==> or !!; it is
   100 recommended to convert to these new commands using isatool fixgoal
   101 (backup your sources first!);
   102 
   103 * new top-level commands 'thm' and 'thms' for retrieving theorems from
   104 the current theory context, and 'theory' to lookup stored theories;
   105 
   106 * new theory section 'nonterminals' for purely syntactic types;
   107 
   108 * new theory section 'setup' for generic ML setup functions
   109 (e.g. package initialization);
   110 
   111 * the distribution now includes Isabelle icons: see
   112 lib/logo/isabelle-{small,tiny}.xpm;
   113 
   114 * isatool install - install binaries with absolute references to
   115 ISABELLE_HOME/bin;
   116 
   117 * isatool logo -- create instances of the Isabelle logo (as EPS);
   118 
   119 * print mode 'emacs' reserved for Isamode;
   120 
   121 
   122 *** HOL ***
   123 
   124 * HOL/inductive package reorganized and improved: now supports mutual
   125 definitions such as
   126 
   127   inductive EVEN ODD
   128     intrs
   129       null "0 : EVEN"
   130       oddI "n : EVEN ==> Suc n : ODD"
   131       evenI "n : ODD ==> Suc n : EVEN"
   132 
   133 new theorem list "elims" contains an elimination rule for each of the
   134 recursive sets; inductive definitions now handle disjunctive premises
   135 correctly (also ZF);
   136 
   137 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   138 "mutual_induct" no longer exists - the induction rule is always
   139 contained in "induct";
   140 
   141 
   142 * HOL/datatype package re-implemented and greatly improved: now
   143 supports mutually recursive datatypes such as
   144 
   145   datatype
   146     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
   147             | SUM ('a aexp) ('a aexp)
   148             | DIFF ('a aexp) ('a aexp)
   149             | NUM 'a
   150   and
   151     'a bexp = LESS ('a aexp) ('a aexp)
   152             | AND ('a bexp) ('a bexp)
   153             | OR ('a bexp) ('a bexp)
   154 
   155 as well as indirectly recursive datatypes such as
   156 
   157   datatype
   158     ('a, 'b) term = Var 'a
   159                   | App 'b ((('a, 'b) term) list)
   160 
   161 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
   162 induction on mutually / indirectly recursive datatypes.
   163 
   164 Primrec equations are now stored in theory and can be accessed via
   165 <function_name>.simps.
   166 
   167 INCOMPATIBILITIES:
   168 
   169   - Theories using datatypes must now have theory Datatype as an
   170     ancestor.
   171   - The specific <typename>.induct_tac no longer exists - use the
   172     generic induct_tac instead.
   173   - natE has been renamed to nat.exhaust - use exhaust_tac
   174     instead of res_inst_tac ... natE. Note that the variable
   175     names in nat.exhaust differ from the names in natE, this
   176     may cause some "fragile" proofs to fail.
   177   - The theorems split_<typename>_case and split_<typename>_case_asm
   178     have been renamed to <typename>.split and <typename>.split_asm.
   179   - Since default sorts of type variables are now handled correctly,
   180     some datatype definitions may have to be annotated with explicit
   181     sort constraints.
   182   - Primrec definitions no longer require function name and type
   183     of recursive argument.
   184 
   185 Consider using isatool fixdatatype to adapt your theories and proof
   186 scripts to the new package (backup your sources first!).
   187 
   188 
   189 * HOL/record package: now includes concrete syntax for record types,
   190 terms, updates; still lacks important theorems, like surjective
   191 pairing and split;
   192 
   193 * reorganized the main HOL image: HOL/Integ and String loaded by
   194 default; theory Main includes everything;
   195 
   196 * automatic simplification of integer sums and comparisons, using cancellation;
   197 
   198 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
   199 
   200 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
   201 
   202 * many new identities for unions, intersections, set difference, etc.;
   203 
   204 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
   205 called split_if, split_split, split_sum_case and split_nat_case (to go
   206 with add/delsplits);
   207 
   208 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
   209 (?x::unit) = (); this is made part of the default simpset, which COULD
   210 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
   211 'Delsimprocs [unit_eq_proc];' as last resort); also note that
   212 unit_abs_eta_conv is added in order to counter the effect of
   213 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
   214 %u.f();
   215 
   216 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
   217 makes more sense);
   218 
   219 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   220   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   221   disjointness reasoning but breaking a few old proofs.
   222 
   223 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
   224 to 'converse' from 'inverse' (for compatibility with ZF and some
   225 literature);
   226 
   227 * HOL/recdef can now declare non-recursive functions, with {} supplied as
   228 the well-founded relation;
   229 
   230 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
   231     Compl A.  The "Compl" syntax remains available as input syntax for this
   232     release ONLY.
   233 
   234 * HOL/Update: new theory of function updates:
   235     f(a:=b) == %x. if x=a then b else f x
   236 may also be iterated as in f(a:=b,c:=d,...);
   237 
   238 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
   239 
   240 * HOL/List:
   241   - new function list_update written xs[i:=v] that updates the i-th
   242     list position. May also be iterated as in xs[i:=a,j:=b,...].
   243   - new function `upt' written [i..j(] which generates the list
   244     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
   245     bound write [i..j], which is a shorthand for [i..j+1(].
   246   - new lexicographic orderings and corresponding wellfoundedness theorems.
   247 
   248 * HOL/Arith:
   249   - removed 'pred' (predecessor) function;
   250   - generalized some theorems about n-1;
   251   - many new laws about "div" and "mod";
   252   - new laws about greatest common divisors (see theory ex/Primes);
   253 
   254 * HOL/Relation: renamed the relational operator r^-1 "converse"
   255 instead of "inverse";
   256 
   257 * directory HOL/Real: a construction of the reals using Dedekind cuts
   258 (not included by default);
   259 
   260 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
   261 
   262 * calling (stac rew i) now fails if "rew" has no effect on the goal
   263   [previously, this check worked only if the rewrite rule was unconditional]
   264   Now rew can involve either definitions or equalities (either == or =).
   265 
   266 
   267 *** ZF ***
   268 
   269 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
   270   only the theorems proved on ZF.ML;
   271 
   272 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   273   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   274   disjointness reasoning but breaking a few old proofs.
   275 
   276 * ZF/Update: new theory of function updates
   277     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
   278   may also be iterated as in f(a:=b,c:=d,...);
   279 
   280 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
   281 
   282 * calling (stac rew i) now fails if "rew" has no effect on the goal
   283   [previously, this check worked only if the rewrite rule was unconditional]
   284   Now rew can involve either definitions or equalities (either == or =).
   285 
   286 * case_tac provided for compatibility with HOL
   287     (like the old excluded_middle_tac, but with subgoals swapped)
   288 
   289 
   290 *** Internal programming interfaces ***
   291 
   292 * Pure: several new basic modules made available for general use, see
   293 also src/Pure/README;
   294 
   295 * improved the theory data mechanism to support encapsulation (data
   296 kind name replaced by private Object.kind, acting as authorization
   297 key); new type-safe user interface via functor TheoryDataFun; generic
   298 print_data function becomes basically useless;
   299 
   300 * removed global_names compatibility flag -- all theory declarations
   301 are qualified by default;
   302 
   303 * module Pure/Syntax now offers quote / antiquote translation
   304 functions (useful for Hoare logic etc. with implicit dependencies);
   305 see HOL/ex/Antiquote for an example use;
   306 
   307 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
   308 cterm -> thm;
   309 
   310 * new tactical CHANGED_GOAL for checking that a tactic modifies a
   311 subgoal;
   312 
   313 * Display.print_goals function moved to Locale.print_goals;
   314 
   315 
   316 
   317 New in Isabelle98 (January 1998)
   318 --------------------------------
   319 
   320 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   321 
   322 * changed lexical syntax of terms / types: dots made part of long
   323 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
   324 
   325 * simpset (and claset) reference variable replaced by functions
   326 simpset / simpset_ref;
   327 
   328 * no longer supports theory aliases (via merge) and non-trivial
   329 implicit merge of thms' signatures;
   330 
   331 * most internal names of constants changed due to qualified names;
   332 
   333 * changed Pure/Sequence interface (see Pure/seq.ML);
   334 
   335 
   336 *** General Changes ***
   337 
   338 * hierachically structured name spaces (for consts, types, axms, thms
   339 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
   340 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
   341 isatool fixdots ensures space after dots (e.g. "%x. x"); set
   342 long_names for fully qualified output names; NOTE: ML programs
   343 (special tactics, packages etc.) referring to internal names may have
   344 to be adapted to cope with fully qualified names; in case of severe
   345 backward campatibility problems try setting 'global_names' at compile
   346 time to have enrything declared within a flat name space; one may also
   347 fine tune name declarations in theories via the 'global' and 'local'
   348 section;
   349 
   350 * reimplemented the implicit simpset and claset using the new anytype
   351 data filed in signatures; references simpset:simpset ref etc. are
   352 replaced by functions simpset:unit->simpset and
   353 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
   354 to patch your ML files accordingly;
   355 
   356 * HTML output now includes theory graph data for display with Java
   357 applet or isatool browser; data generated automatically via isatool
   358 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
   359 
   360 * defs may now be conditional; improved rewrite_goals_tac to handle
   361 conditional equations;
   362 
   363 * defs now admits additional type arguments, using TYPE('a) syntax;
   364 
   365 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
   366 creates a new theory node; implicit merge of thms' signatures is
   367 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
   368 transfer:theory->thm->thm in (rare) cases;
   369 
   370 * improved handling of draft signatures / theories; draft thms (and
   371 ctyps, cterms) are automatically promoted to real ones;
   372 
   373 * slightly changed interfaces for oracles: admit many per theory, named
   374 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
   375 
   376 * print_goals: optional output of const types (set show_consts and
   377 show_types);
   378 
   379 * improved output of warnings (###) and errors (***);
   380 
   381 * subgoal_tac displays a warning if the new subgoal has type variables;
   382 
   383 * removed old README and Makefiles;
   384 
   385 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
   386 
   387 * removed obsolete init_pps and init_database;
   388 
   389 * deleted the obsolete tactical STATE, which was declared by
   390     fun STATE tacfun st = tacfun st st;
   391 
   392 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
   393 (which abbreviates $HOME);
   394 
   395 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
   396 use isatool fixseq to adapt your ML programs (this works for fully
   397 qualified references to the Sequence structure only!);
   398 
   399 * use_thy no longer requires writable current directory; it always
   400 reloads .ML *and* .thy file, if either one is out of date;
   401 
   402 
   403 *** Classical Reasoner ***
   404 
   405 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
   406 tactics that use classical reasoning to simplify a subgoal without
   407 splitting it into several subgoals;
   408 
   409 * Safe_tac: like safe_tac but uses the default claset;
   410 
   411 
   412 *** Simplifier ***
   413 
   414 * added simplification meta rules:
   415     (asm_)(full_)simplify: simpset -> thm -> thm;
   416 
   417 * simplifier.ML no longer part of Pure -- has to be loaded by object
   418 logics (again);
   419 
   420 * added prems argument to simplification procedures;
   421 
   422 * HOL, FOL, ZF: added infix function `addsplits':
   423   instead of `<simpset> setloop (split_tac <thms>)'
   424   you can simply write `<simpset> addsplits <thms>'
   425 
   426 
   427 *** Syntax ***
   428 
   429 * TYPE('a) syntax for type reflection terms;
   430 
   431 * no longer handles consts with name "" -- declare as 'syntax' instead;
   432 
   433 * pretty printer: changed order of mixfix annotation preference (again!);
   434 
   435 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
   436 
   437 
   438 *** HOL ***
   439 
   440 * HOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   441   with `addloop' of the simplifier to faciliate case splitting in premises.
   442 
   443 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
   444 
   445 * HOL/Auth: new protocol proofs including some for the Internet
   446   protocol TLS;
   447 
   448 * HOL/Map: new theory of `maps' a la VDM;
   449 
   450 * HOL/simplifier: simplification procedures nat_cancel_sums for
   451 cancelling out common nat summands from =, <, <= (in)equalities, or
   452 differences; simplification procedures nat_cancel_factor for
   453 cancelling common factor from =, <, <= (in)equalities over natural
   454 sums; nat_cancel contains both kinds of procedures, it is installed by
   455 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
   456 
   457 * HOL/simplifier: terms of the form
   458   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
   459   are rewritten to
   460   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
   461   and those of the form
   462   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
   463   are rewritten to
   464   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
   465 
   466 * HOL/datatype
   467   Each datatype `t' now comes with a theorem `split_t_case' of the form
   468 
   469   P(t_case f1 ... fn x) =
   470      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
   471         ...
   472        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
   473      )
   474 
   475   and a theorem `split_t_case_asm' of the form
   476 
   477   P(t_case f1 ... fn x) =
   478     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
   479         ...
   480        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
   481      )
   482   which can be added to a simpset via `addsplits'. The existing theorems
   483   expand_list_case and expand_option_case have been renamed to
   484   split_list_case and split_option_case.
   485 
   486 * HOL/Arithmetic:
   487   - `pred n' is automatically converted to `n-1'.
   488     Users are strongly encouraged not to use `pred' any longer,
   489     because it will disappear altogether at some point.
   490   - Users are strongly encouraged to write "0 < n" rather than
   491     "n ~= 0". Theorems and proof tools have been modified towards this
   492     `standard'.
   493 
   494 * HOL/Lists:
   495   the function "set_of_list" has been renamed "set" (and its theorems too);
   496   the function "nth" now takes its arguments in the reverse order and
   497   has acquired the infix notation "!" as in "xs!n".
   498 
   499 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
   500 
   501 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
   502   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
   503 
   504 * HOL/record: extensible records with schematic structural subtyping
   505 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
   506 still lacks various theorems and concrete record syntax;
   507 
   508 
   509 *** HOLCF ***
   510 
   511 * removed "axioms" and "generated by" sections;
   512 
   513 * replaced "ops" section by extended "consts" section, which is capable of
   514   handling the continuous function space "->" directly;
   515 
   516 * domain package:
   517   . proves theorems immediately and stores them in the theory,
   518   . creates hierachical name space,
   519   . now uses normal mixfix annotations (instead of cinfix...),
   520   . minor changes to some names and values (for consistency),
   521   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
   522   . separator between mutual domain defs: changed "," to "and",
   523   . improved handling of sort constraints;  now they have to
   524     appear on the left-hand side of the equations only;
   525 
   526 * fixed LAM <x,y,zs>.b syntax;
   527 
   528 * added extended adm_tac to simplifier in HOLCF -- can now discharge
   529 adm (%x. P (t x)), where P is chainfinite and t continuous;
   530 
   531 
   532 *** FOL and ZF ***
   533 
   534 * FOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   535   with `addloop' of the simplifier to faciliate case splitting in premises.
   536 
   537 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
   538 in HOL, they strip ALL and --> from proved theorems;
   539 
   540 
   541 
   542 New in Isabelle94-8 (May 1997)
   543 ------------------------------
   544 
   545 *** General Changes ***
   546 
   547 * new utilities to build / run / maintain Isabelle etc. (in parts
   548 still somewhat experimental); old Makefiles etc. still functional;
   549 
   550 * new 'Isabelle System Manual';
   551 
   552 * INSTALL text, together with ./configure and ./build scripts;
   553 
   554 * reimplemented type inference for greater efficiency, better error
   555 messages and clean internal interface;
   556 
   557 * prlim command for dealing with lots of subgoals (an easier way of
   558 setting goals_limit);
   559 
   560 
   561 *** Syntax ***
   562 
   563 * supports alternative (named) syntax tables (parser and pretty
   564 printer); internal interface is provided by add_modesyntax(_i);
   565 
   566 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
   567 be used in conjunction with the Isabelle symbol font; uses the
   568 "symbols" syntax table;
   569 
   570 * added token_translation interface (may translate name tokens in
   571 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
   572 the current print_mode); IMPORTANT: user print translation functions
   573 are responsible for marking newly introduced bounds
   574 (Syntax.mark_boundT);
   575 
   576 * token translations for modes "xterm" and "xterm_color" that display
   577 names in bold, underline etc. or colors (which requires a color
   578 version of xterm);
   579 
   580 * infixes may now be declared with names independent of their syntax;
   581 
   582 * added typed_print_translation (like print_translation, but may
   583 access type of constant);
   584 
   585 
   586 *** Classical Reasoner ***
   587 
   588 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
   589 some limitations.  Blast_tac...
   590   + ignores addss, addbefore, addafter; this restriction is intrinsic
   591   + ignores elimination rules that don't have the correct format
   592 	(the conclusion MUST be a formula variable)
   593   + ignores types, which can make HOL proofs fail
   594   + rules must not require higher-order unification, e.g. apply_type in ZF
   595     [message "Function Var's argument not a bound variable" relates to this]
   596   + its proof strategy is more general but can actually be slower
   597 
   598 * substitution with equality assumptions no longer permutes other
   599 assumptions;
   600 
   601 * minor changes in semantics of addafter (now called addaltern); renamed
   602 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
   603 (and access functions for it);
   604 
   605 * improved combination of classical reasoner and simplifier: 
   606   + functions for handling clasimpsets
   607   + improvement of addss: now the simplifier is called _after_ the
   608     safe steps.
   609   + safe variant of addss called addSss: uses safe simplifications
   610     _during_ the safe steps. It is more complete as it allows multiple 
   611     instantiations of unknowns (e.g. with slow_tac).
   612 
   613 *** Simplifier ***
   614 
   615 * added interface for simplification procedures (functions that
   616 produce *proven* rewrite rules on the fly, depending on current
   617 redex);
   618 
   619 * ordering on terms as parameter (used for ordered rewriting);
   620 
   621 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
   622 
   623 * the solver is now split into a safe and an unsafe part.
   624 This should be invisible for the normal user, except that the
   625 functions setsolver and addsolver have been renamed to setSolver and
   626 addSolver; added safe_asm_full_simp_tac;
   627 
   628 
   629 *** HOL ***
   630 
   631 * a generic induction tactic `induct_tac' which works for all datatypes and
   632 also for type `nat';
   633 
   634 * a generic case distinction tactic `exhaust_tac' which works for all
   635 datatypes and also for type `nat';
   636 
   637 * each datatype comes with a function `size';
   638 
   639 * patterns in case expressions allow tuple patterns as arguments to
   640 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
   641 
   642 * primrec now also works with type nat;
   643 
   644 * recdef: a new declaration form, allows general recursive functions to be
   645 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
   646 
   647 * the constant for negation has been renamed from "not" to "Not" to
   648 harmonize with FOL, ZF, LK, etc.;
   649 
   650 * HOL/ex/LFilter theory of a corecursive "filter" functional for
   651 infinite lists;
   652 
   653 * HOL/Modelcheck demonstrates invocation of model checker oracle;
   654 
   655 * HOL/ex/Ring.thy declares cring_simp, which solves equational
   656 problems in commutative rings, using axiomatic type classes for + and *;
   657 
   658 * more examples in HOL/MiniML and HOL/Auth;
   659 
   660 * more default rewrite rules for quantifiers, union/intersection;
   661 
   662 * a new constant `arbitrary == @x.False';
   663 
   664 * HOLCF/IOA replaces old HOL/IOA;
   665 
   666 * HOLCF changes: derived all rules and arities 
   667   + axiomatic type classes instead of classes 
   668   + typedef instead of faking type definitions
   669   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
   670   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
   671   + eliminated the types void, one, tr
   672   + use unit lift and bool lift (with translations) instead of one and tr
   673   + eliminated blift from Lift3.thy (use Def instead of blift)
   674   all eliminated rules are derived as theorems --> no visible changes ;
   675 
   676 
   677 *** ZF ***
   678 
   679 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
   680 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
   681 as ZF_cs addSIs [equalityI];
   682 
   683 
   684 
   685 New in Isabelle94-7 (November 96)
   686 ---------------------------------
   687 
   688 * allowing negative levels (as offsets) in prlev and choplev;
   689 
   690 * super-linear speedup for large simplifications;
   691 
   692 * FOL, ZF and HOL now use miniscoping: rewriting pushes
   693 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
   694 FAIL); can suppress it using the command Delsimps (ex_simps @
   695 all_simps); De Morgan laws are also now included, by default;
   696 
   697 * improved printing of ==>  :  ~:
   698 
   699 * new object-logic "Sequents" adds linear logic, while replacing LK
   700 and Modal (thanks to Sara Kalvala);
   701 
   702 * HOL/Auth: correctness proofs for authentication protocols;
   703 
   704 * HOL: new auto_tac combines rewriting and classical reasoning (many
   705 examples on HOL/Auth);
   706 
   707 * HOL: new command AddIffs for declaring theorems of the form P=Q to
   708 the rewriter and classical reasoner simultaneously;
   709 
   710 * function uresult no longer returns theorems in "standard" format;
   711 regain previous version by: val uresult = standard o uresult;
   712 
   713 
   714 
   715 New in Isabelle94-6
   716 -------------------
   717 
   718 * oracles -- these establish an interface between Isabelle and trusted
   719 external reasoners, which may deliver results as theorems;
   720 
   721 * proof objects (in particular record all uses of oracles);
   722 
   723 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
   724 
   725 * "constdefs" section in theory files;
   726 
   727 * "primrec" section (HOL) no longer requires names;
   728 
   729 * internal type "tactic" now simply "thm -> thm Sequence.seq";
   730 
   731 
   732 
   733 New in Isabelle94-5
   734 -------------------
   735 
   736 * reduced space requirements;
   737 
   738 * automatic HTML generation from theories;
   739 
   740 * theory files no longer require "..." (quotes) around most types;
   741 
   742 * new examples, including two proofs of the Church-Rosser theorem;
   743 
   744 * non-curried (1994) version of HOL is no longer distributed;
   745 
   746 
   747 
   748 New in Isabelle94-4
   749 -------------------
   750 
   751 * greatly reduced space requirements;
   752 
   753 * theory files (.thy) no longer require \...\ escapes at line breaks;
   754 
   755 * searchable theorem database (see the section "Retrieving theorems" on 
   756 page 8 of the Reference Manual);
   757 
   758 * new examples, including Grabczewski's monumental case study of the
   759 Axiom of Choice;
   760 
   761 * The previous version of HOL renamed to Old_HOL;
   762 
   763 * The new version of HOL (previously called CHOL) uses a curried syntax 
   764 for functions.  Application looks like f a b instead of f(a,b);
   765 
   766 * Mutually recursive inductive definitions finally work in HOL;
   767 
   768 * In ZF, pattern-matching on tuples is now available in all abstractions and
   769 translates to the operator "split";
   770 
   771 
   772 
   773 New in Isabelle94-3
   774 -------------------
   775 
   776 * new infix operator, addss, allowing the classical reasoner to 
   777 perform simplification at each step of its search.  Example:
   778 	fast_tac (cs addss ss)
   779 
   780 * a new logic, CHOL, the same as HOL, but with a curried syntax 
   781 for functions.  Application looks like f a b instead of f(a,b).  Also pairs 
   782 look like (a,b) instead of <a,b>;
   783 
   784 * PLEASE NOTE: CHOL will eventually replace HOL!
   785 
   786 * In CHOL, pattern-matching on tuples is now available in all abstractions.
   787 It translates to the operator "split".  A new theory of integers is available;
   788 
   789 * In ZF, integer numerals now denote two's-complement binary integers.
   790 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
   791 
   792 * Many new examples: I/O automata, Church-Rosser theorem, equivalents 
   793 of the Axiom of Choice;
   794 
   795 
   796 
   797 New in Isabelle94-2
   798 -------------------
   799 
   800 * Significantly faster resolution;  
   801 
   802 * the different sections in a .thy file can now be mixed and repeated
   803 freely;
   804 
   805 * Database of theorems for FOL, HOL and ZF.  New
   806 commands including qed, qed_goal and bind_thm store theorems in the database.
   807 
   808 * Simple database queries: return a named theorem (get_thm) or all theorems of
   809 a given theory (thms_of), or find out what theory a theorem was proved in
   810 (theory_of_thm);
   811 
   812 * Bugs fixed in the inductive definition and datatype packages;
   813 
   814 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
   815 and HOL_dup_cs obsolete;
   816 
   817 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
   818 have been removed;
   819 
   820 * Simpler definition of function space in ZF;
   821 
   822 * new results about cardinal and ordinal arithmetic in ZF;
   823 
   824 * 'subtype' facility in HOL for introducing new types as subsets of existing
   825 types;
   826 
   827 
   828 $Id$