NEWS
author wenzelm
Wed Oct 21 13:01:17 1998 +0200 (1998-10-21)
changeset 5705 56f2030c46c6
parent 5671 da670b37857e
child 5709 35b07f8e67b6
permissions -rw-r--r--
tuned (all proofs are INSTABLE by David's definition of instability);
     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:
    35   1. Asm_full_simp_tac is now more aggressive.
    36      1. It will sometimes reorient premises if that increases their power to
    37         simplify.
    38      2. It does no longer proceed strictly from left to right but may also
    39         rotate premises to achieve further simplification.
    40      For compatibility reasons there is now Asm_lr_simp_tac which is like the
    41      old Asm_full_simp_tac in that it does not rotate premises.
    42   2. The simplifier now knows a little bit about nat-arithmetic.
    43 
    44 * Classical reasoner: wrapper mechanism for the classical reasoner now
    45 allows for selected deletion of wrappers, by introduction of names for
    46 wrapper functionals.  This implies that addbefore, addSbefore,
    47 addaltern, and addSaltern now take a pair (name, tactic) as argument,
    48 and that adding two tactics with the same name overwrites the first
    49 one (emitting a warning).
    50   type wrapper = (int -> tactic) -> (int -> tactic)
    51   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
    52   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
    53   delWrapper, delSWrapper: claset *  string            -> claset
    54   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
    55 
    56 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
    57   semantics; addbefore now affects only the unsafe part of step_tac
    58   etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
    59   FAIL, but proofs should be fixable easily, e.g. by replacing
    60   Auto_tac by Force_tac;
    61 
    62 * Classical reasoner: setwrapper to setWrapper and compwrapper to compWrapper; 
    63   added safe wrapper (and access functions for it);
    64 
    65 * HOL/split_all_tac is now much faster and fails if there is nothing
    66 to split.  Existing (fragile) proofs may require adaption because the
    67 order and the names of the automatically generated variables have
    68 changed.  split_all_tac has moved within claset() from unsafe wrappers
    69 to safe wrappers, which means that !!-bound variables are split much
    70 more aggressively, and safe_tac and clarify_tac now split such
    71 variables.  If this splitting is not appropriate, use delSWrapper
    72 "split_all_tac".
    73 
    74 * HOL/Simplifier:
    75 
    76  - Rewrite rules for case distinctions can now be added permanently to
    77    the default simpset using Addsplits just like Addsimps. They can be
    78    removed via Delsplits just like Delsimps. Lower-case versions are
    79    also available.
    80 
    81  - The rule split_if is now part of the default simpset. This means
    82    that the simplifier will eliminate all occurrences of if-then-else
    83    in the conclusion of a goal. To prevent this, you can either remove
    84    split_if completely from the default simpset by `Delsplits
    85    [split_if]' or remove it in a specific call of the simplifier using
    86    `... delsplits [split_if]'.  You can also add/delete other case
    87    splitting rules to/from the default simpset: every datatype
    88    generates suitable rules `split_t_case' and `split_t_case_asm'
    89    (where t is the name of the datatype).
    90 
    91 * Classical reasoner - Simplifier combination: new force_tac (and
    92 derivatives Force_tac, force) combines rewriting and classical
    93 reasoning (and whatever other tools) similarly to auto_tac, but is
    94 aimed to solve the given subgoal completely;
    95 
    96 
    97 *** General ***
    98 
    99 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
   100 and `goalw': the theory is no longer needed as an explicit argument -
   101 the current theory context is used; assumptions are no longer returned
   102 at the ML-level unless one of them starts with ==> or !!; it is
   103 recommended to convert to these new commands using isatool fixgoal
   104 (backup your sources first!);
   105 
   106 * new top-level commands 'thm' and 'thms' for retrieving theorems from
   107 the current theory context, and 'theory' to lookup stored theories;
   108 
   109 * new theory section 'nonterminals' for purely syntactic types;
   110 
   111 * new theory section 'setup' for generic ML setup functions
   112 (e.g. package initialization);
   113 
   114 * the distribution now includes Isabelle icons: see
   115 lib/logo/isabelle-{small,tiny}.xpm;
   116 
   117 * isatool install - install binaries with absolute references to
   118 ISABELLE_HOME/bin;
   119 
   120 * isatool logo -- create instances of the Isabelle logo (as EPS);
   121 
   122 * print mode 'emacs' reserved for Isamode;
   123 
   124 
   125 *** HOL ***
   126 
   127 * HOL/inductive package reorganized and improved: now supports mutual
   128 definitions such as
   129 
   130   inductive EVEN ODD
   131     intrs
   132       null "0 : EVEN"
   133       oddI "n : EVEN ==> Suc n : ODD"
   134       evenI "n : ODD ==> Suc n : EVEN"
   135 
   136 new theorem list "elims" contains an elimination rule for each of the
   137 recursive sets; inductive definitions now handle disjunctive premises
   138 correctly (also ZF);
   139 
   140 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   141 "mutual_induct" no longer exists - the induction rule is always
   142 contained in "induct";
   143 
   144 
   145 * HOL/datatype package re-implemented and greatly improved: now
   146 supports mutually recursive datatypes such as
   147 
   148   datatype
   149     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
   150             | SUM ('a aexp) ('a aexp)
   151             | DIFF ('a aexp) ('a aexp)
   152             | NUM 'a
   153   and
   154     'a bexp = LESS ('a aexp) ('a aexp)
   155             | AND ('a bexp) ('a bexp)
   156             | OR ('a bexp) ('a bexp)
   157 
   158 as well as indirectly recursive datatypes such as
   159 
   160   datatype
   161     ('a, 'b) term = Var 'a
   162                   | App 'b ((('a, 'b) term) list)
   163 
   164 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
   165 induction on mutually / indirectly recursive datatypes.
   166 
   167 Primrec equations are now stored in theory and can be accessed via
   168 <function_name>.simps.
   169 
   170 INCOMPATIBILITIES:
   171 
   172   - Theories using datatypes must now have theory Datatype as an
   173     ancestor.
   174   - The specific <typename>.induct_tac no longer exists - use the
   175     generic induct_tac instead.
   176   - natE has been renamed to nat.exhaust - use exhaust_tac
   177     instead of res_inst_tac ... natE. Note that the variable
   178     names in nat.exhaust differ from the names in natE, this
   179     may cause some "fragile" proofs to fail.
   180   - The theorems split_<typename>_case and split_<typename>_case_asm
   181     have been renamed to <typename>.split and <typename>.split_asm.
   182   - Since default sorts of type variables are now handled correctly,
   183     some datatype definitions may have to be annotated with explicit
   184     sort constraints.
   185   - Primrec definitions no longer require function name and type
   186     of recursive argument.
   187 
   188 Consider using isatool fixdatatype to adapt your theories and proof
   189 scripts to the new package (backup your sources first!).
   190 
   191 
   192 * HOL/record package: now includes concrete syntax for record types,
   193 terms, updates; still lacks important theorems, like surjective
   194 pairing and split;
   195 
   196 * reorganized the main HOL image: HOL/Integ and String loaded by
   197 default; theory Main includes everything;
   198 
   199 * automatic simplification of integer sums and comparisons, using cancellation;
   200 
   201 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
   202 
   203 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
   204 
   205 * many new identities for unions, intersections, set difference, etc.;
   206 
   207 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
   208 called split_if, split_split, split_sum_case and split_nat_case (to go
   209 with add/delsplits);
   210 
   211 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
   212 (?x::unit) = (); this is made part of the default simpset, which COULD
   213 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
   214 'Delsimprocs [unit_eq_proc];' as last resort); also note that
   215 unit_abs_eta_conv is added in order to counter the effect of
   216 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
   217 %u.f();
   218 
   219 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
   220 makes more sense);
   221 
   222 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   223   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   224   disjointness reasoning but breaking a few old proofs.
   225 
   226 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
   227 to 'converse' from 'inverse' (for compatibility with ZF and some
   228 literature);
   229 
   230 * HOL/recdef can now declare non-recursive functions, with {} supplied as
   231 the well-founded relation;
   232 
   233 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
   234     Compl A.  The "Compl" syntax remains available as input syntax for this
   235     release ONLY.
   236 
   237 * HOL/Update: new theory of function updates:
   238     f(a:=b) == %x. if x=a then b else f x
   239 may also be iterated as in f(a:=b,c:=d,...);
   240 
   241 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
   242 
   243 * HOL/List:
   244   - new function list_update written xs[i:=v] that updates the i-th
   245     list position. May also be iterated as in xs[i:=a,j:=b,...].
   246   - new function `upt' written [i..j(] which generates the list
   247     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
   248     bound write [i..j], which is a shorthand for [i..j+1(].
   249   - new lexicographic orderings and corresponding wellfoundedness theorems.
   250 
   251 * HOL/Arith:
   252   - removed 'pred' (predecessor) function;
   253   - generalized some theorems about n-1;
   254   - many new laws about "div" and "mod";
   255   - new laws about greatest common divisors (see theory ex/Primes);
   256 
   257 * HOL/Relation: renamed the relational operator r^-1 "converse"
   258 instead of "inverse";
   259 
   260 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
   261   of the multiset ordering;
   262 
   263 * directory HOL/Real: a construction of the reals using Dedekind cuts
   264   (not included by default);
   265 
   266 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
   267 
   268 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
   269   programs, i.e. different program variables may have different types.
   270 
   271 * calling (stac rew i) now fails if "rew" has no effect on the goal
   272   [previously, this check worked only if the rewrite rule was unconditional]
   273   Now rew can involve either definitions or equalities (either == or =).
   274 
   275 
   276 *** ZF ***
   277 
   278 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
   279   only the theorems proved on ZF.ML;
   280 
   281 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   282   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   283   disjointness reasoning but breaking a few old proofs.
   284 
   285 * ZF/Update: new theory of function updates
   286     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
   287   may also be iterated as in f(a:=b,c:=d,...);
   288 
   289 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
   290 
   291 * calling (stac rew i) now fails if "rew" has no effect on the goal
   292   [previously, this check worked only if the rewrite rule was unconditional]
   293   Now rew can involve either definitions or equalities (either == or =).
   294 
   295 * case_tac provided for compatibility with HOL
   296     (like the old excluded_middle_tac, but with subgoals swapped)
   297 
   298 
   299 *** Internal programming interfaces ***
   300 
   301 * Pure: several new basic modules made available for general use, see
   302 also src/Pure/README;
   303 
   304 * improved the theory data mechanism to support encapsulation (data
   305 kind name replaced by private Object.kind, acting as authorization
   306 key); new type-safe user interface via functor TheoryDataFun; generic
   307 print_data function becomes basically useless;
   308 
   309 * removed global_names compatibility flag -- all theory declarations
   310 are qualified by default;
   311 
   312 * module Pure/Syntax now offers quote / antiquote translation
   313 functions (useful for Hoare logic etc. with implicit dependencies);
   314 see HOL/ex/Antiquote for an example use;
   315 
   316 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
   317 cterm -> thm;
   318 
   319 * new tactical CHANGED_GOAL for checking that a tactic modifies a
   320 subgoal;
   321 
   322 * Display.print_goals function moved to Locale.print_goals;
   323 
   324 
   325 
   326 New in Isabelle98 (January 1998)
   327 --------------------------------
   328 
   329 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   330 
   331 * changed lexical syntax of terms / types: dots made part of long
   332 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
   333 
   334 * simpset (and claset) reference variable replaced by functions
   335 simpset / simpset_ref;
   336 
   337 * no longer supports theory aliases (via merge) and non-trivial
   338 implicit merge of thms' signatures;
   339 
   340 * most internal names of constants changed due to qualified names;
   341 
   342 * changed Pure/Sequence interface (see Pure/seq.ML);
   343 
   344 
   345 *** General Changes ***
   346 
   347 * hierachically structured name spaces (for consts, types, axms, thms
   348 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
   349 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
   350 isatool fixdots ensures space after dots (e.g. "%x. x"); set
   351 long_names for fully qualified output names; NOTE: ML programs
   352 (special tactics, packages etc.) referring to internal names may have
   353 to be adapted to cope with fully qualified names; in case of severe
   354 backward campatibility problems try setting 'global_names' at compile
   355 time to have enrything declared within a flat name space; one may also
   356 fine tune name declarations in theories via the 'global' and 'local'
   357 section;
   358 
   359 * reimplemented the implicit simpset and claset using the new anytype
   360 data filed in signatures; references simpset:simpset ref etc. are
   361 replaced by functions simpset:unit->simpset and
   362 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
   363 to patch your ML files accordingly;
   364 
   365 * HTML output now includes theory graph data for display with Java
   366 applet or isatool browser; data generated automatically via isatool
   367 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
   368 
   369 * defs may now be conditional; improved rewrite_goals_tac to handle
   370 conditional equations;
   371 
   372 * defs now admits additional type arguments, using TYPE('a) syntax;
   373 
   374 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
   375 creates a new theory node; implicit merge of thms' signatures is
   376 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
   377 transfer:theory->thm->thm in (rare) cases;
   378 
   379 * improved handling of draft signatures / theories; draft thms (and
   380 ctyps, cterms) are automatically promoted to real ones;
   381 
   382 * slightly changed interfaces for oracles: admit many per theory, named
   383 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
   384 
   385 * print_goals: optional output of const types (set show_consts and
   386 show_types);
   387 
   388 * improved output of warnings (###) and errors (***);
   389 
   390 * subgoal_tac displays a warning if the new subgoal has type variables;
   391 
   392 * removed old README and Makefiles;
   393 
   394 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
   395 
   396 * removed obsolete init_pps and init_database;
   397 
   398 * deleted the obsolete tactical STATE, which was declared by
   399     fun STATE tacfun st = tacfun st st;
   400 
   401 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
   402 (which abbreviates $HOME);
   403 
   404 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
   405 use isatool fixseq to adapt your ML programs (this works for fully
   406 qualified references to the Sequence structure only!);
   407 
   408 * use_thy no longer requires writable current directory; it always
   409 reloads .ML *and* .thy file, if either one is out of date;
   410 
   411 
   412 *** Classical Reasoner ***
   413 
   414 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
   415 tactics that use classical reasoning to simplify a subgoal without
   416 splitting it into several subgoals;
   417 
   418 * Safe_tac: like safe_tac but uses the default claset;
   419 
   420 
   421 *** Simplifier ***
   422 
   423 * added simplification meta rules:
   424     (asm_)(full_)simplify: simpset -> thm -> thm;
   425 
   426 * simplifier.ML no longer part of Pure -- has to be loaded by object
   427 logics (again);
   428 
   429 * added prems argument to simplification procedures;
   430 
   431 * HOL, FOL, ZF: added infix function `addsplits':
   432   instead of `<simpset> setloop (split_tac <thms>)'
   433   you can simply write `<simpset> addsplits <thms>'
   434 
   435 
   436 *** Syntax ***
   437 
   438 * TYPE('a) syntax for type reflection terms;
   439 
   440 * no longer handles consts with name "" -- declare as 'syntax' instead;
   441 
   442 * pretty printer: changed order of mixfix annotation preference (again!);
   443 
   444 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
   445 
   446 
   447 *** HOL ***
   448 
   449 * HOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   450   with `addloop' of the simplifier to faciliate case splitting in premises.
   451 
   452 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
   453 
   454 * HOL/Auth: new protocol proofs including some for the Internet
   455   protocol TLS;
   456 
   457 * HOL/Map: new theory of `maps' a la VDM;
   458 
   459 * HOL/simplifier: simplification procedures nat_cancel_sums for
   460 cancelling out common nat summands from =, <, <= (in)equalities, or
   461 differences; simplification procedures nat_cancel_factor for
   462 cancelling common factor from =, <, <= (in)equalities over natural
   463 sums; nat_cancel contains both kinds of procedures, it is installed by
   464 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
   465 
   466 * HOL/simplifier: terms of the form
   467   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
   468   are rewritten to
   469   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
   470   and those of the form
   471   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
   472   are rewritten to
   473   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
   474 
   475 * HOL/datatype
   476   Each datatype `t' now comes with a theorem `split_t_case' of the form
   477 
   478   P(t_case f1 ... fn x) =
   479      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
   480         ...
   481        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
   482      )
   483 
   484   and a theorem `split_t_case_asm' of the form
   485 
   486   P(t_case f1 ... fn x) =
   487     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
   488         ...
   489        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
   490      )
   491   which can be added to a simpset via `addsplits'. The existing theorems
   492   expand_list_case and expand_option_case have been renamed to
   493   split_list_case and split_option_case.
   494 
   495 * HOL/Arithmetic:
   496   - `pred n' is automatically converted to `n-1'.
   497     Users are strongly encouraged not to use `pred' any longer,
   498     because it will disappear altogether at some point.
   499   - Users are strongly encouraged to write "0 < n" rather than
   500     "n ~= 0". Theorems and proof tools have been modified towards this
   501     `standard'.
   502 
   503 * HOL/Lists:
   504   the function "set_of_list" has been renamed "set" (and its theorems too);
   505   the function "nth" now takes its arguments in the reverse order and
   506   has acquired the infix notation "!" as in "xs!n".
   507 
   508 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
   509 
   510 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
   511   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
   512 
   513 * HOL/record: extensible records with schematic structural subtyping
   514 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
   515 still lacks various theorems and concrete record syntax;
   516 
   517 
   518 *** HOLCF ***
   519 
   520 * removed "axioms" and "generated by" sections;
   521 
   522 * replaced "ops" section by extended "consts" section, which is capable of
   523   handling the continuous function space "->" directly;
   524 
   525 * domain package:
   526   . proves theorems immediately and stores them in the theory,
   527   . creates hierachical name space,
   528   . now uses normal mixfix annotations (instead of cinfix...),
   529   . minor changes to some names and values (for consistency),
   530   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
   531   . separator between mutual domain defs: changed "," to "and",
   532   . improved handling of sort constraints;  now they have to
   533     appear on the left-hand side of the equations only;
   534 
   535 * fixed LAM <x,y,zs>.b syntax;
   536 
   537 * added extended adm_tac to simplifier in HOLCF -- can now discharge
   538 adm (%x. P (t x)), where P is chainfinite and t continuous;
   539 
   540 
   541 *** FOL and ZF ***
   542 
   543 * FOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   544   with `addloop' of the simplifier to faciliate case splitting in premises.
   545 
   546 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
   547 in HOL, they strip ALL and --> from proved theorems;
   548 
   549 
   550 
   551 New in Isabelle94-8 (May 1997)
   552 ------------------------------
   553 
   554 *** General Changes ***
   555 
   556 * new utilities to build / run / maintain Isabelle etc. (in parts
   557 still somewhat experimental); old Makefiles etc. still functional;
   558 
   559 * new 'Isabelle System Manual';
   560 
   561 * INSTALL text, together with ./configure and ./build scripts;
   562 
   563 * reimplemented type inference for greater efficiency, better error
   564 messages and clean internal interface;
   565 
   566 * prlim command for dealing with lots of subgoals (an easier way of
   567 setting goals_limit);
   568 
   569 
   570 *** Syntax ***
   571 
   572 * supports alternative (named) syntax tables (parser and pretty
   573 printer); internal interface is provided by add_modesyntax(_i);
   574 
   575 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
   576 be used in conjunction with the Isabelle symbol font; uses the
   577 "symbols" syntax table;
   578 
   579 * added token_translation interface (may translate name tokens in
   580 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
   581 the current print_mode); IMPORTANT: user print translation functions
   582 are responsible for marking newly introduced bounds
   583 (Syntax.mark_boundT);
   584 
   585 * token translations for modes "xterm" and "xterm_color" that display
   586 names in bold, underline etc. or colors (which requires a color
   587 version of xterm);
   588 
   589 * infixes may now be declared with names independent of their syntax;
   590 
   591 * added typed_print_translation (like print_translation, but may
   592 access type of constant);
   593 
   594 
   595 *** Classical Reasoner ***
   596 
   597 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
   598 some limitations.  Blast_tac...
   599   + ignores addss, addbefore, addafter; this restriction is intrinsic
   600   + ignores elimination rules that don't have the correct format
   601 	(the conclusion MUST be a formula variable)
   602   + ignores types, which can make HOL proofs fail
   603   + rules must not require higher-order unification, e.g. apply_type in ZF
   604     [message "Function Var's argument not a bound variable" relates to this]
   605   + its proof strategy is more general but can actually be slower
   606 
   607 * substitution with equality assumptions no longer permutes other
   608 assumptions;
   609 
   610 * minor changes in semantics of addafter (now called addaltern); renamed
   611 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
   612 (and access functions for it);
   613 
   614 * improved combination of classical reasoner and simplifier: 
   615   + functions for handling clasimpsets
   616   + improvement of addss: now the simplifier is called _after_ the
   617     safe steps.
   618   + safe variant of addss called addSss: uses safe simplifications
   619     _during_ the safe steps. It is more complete as it allows multiple 
   620     instantiations of unknowns (e.g. with slow_tac).
   621 
   622 *** Simplifier ***
   623 
   624 * added interface for simplification procedures (functions that
   625 produce *proven* rewrite rules on the fly, depending on current
   626 redex);
   627 
   628 * ordering on terms as parameter (used for ordered rewriting);
   629 
   630 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
   631 
   632 * the solver is now split into a safe and an unsafe part.
   633 This should be invisible for the normal user, except that the
   634 functions setsolver and addsolver have been renamed to setSolver and
   635 addSolver; added safe_asm_full_simp_tac;
   636 
   637 
   638 *** HOL ***
   639 
   640 * a generic induction tactic `induct_tac' which works for all datatypes and
   641 also for type `nat';
   642 
   643 * a generic case distinction tactic `exhaust_tac' which works for all
   644 datatypes and also for type `nat';
   645 
   646 * each datatype comes with a function `size';
   647 
   648 * patterns in case expressions allow tuple patterns as arguments to
   649 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
   650 
   651 * primrec now also works with type nat;
   652 
   653 * recdef: a new declaration form, allows general recursive functions to be
   654 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
   655 
   656 * the constant for negation has been renamed from "not" to "Not" to
   657 harmonize with FOL, ZF, LK, etc.;
   658 
   659 * HOL/ex/LFilter theory of a corecursive "filter" functional for
   660 infinite lists;
   661 
   662 * HOL/Modelcheck demonstrates invocation of model checker oracle;
   663 
   664 * HOL/ex/Ring.thy declares cring_simp, which solves equational
   665 problems in commutative rings, using axiomatic type classes for + and *;
   666 
   667 * more examples in HOL/MiniML and HOL/Auth;
   668 
   669 * more default rewrite rules for quantifiers, union/intersection;
   670 
   671 * a new constant `arbitrary == @x.False';
   672 
   673 * HOLCF/IOA replaces old HOL/IOA;
   674 
   675 * HOLCF changes: derived all rules and arities 
   676   + axiomatic type classes instead of classes 
   677   + typedef instead of faking type definitions
   678   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
   679   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
   680   + eliminated the types void, one, tr
   681   + use unit lift and bool lift (with translations) instead of one and tr
   682   + eliminated blift from Lift3.thy (use Def instead of blift)
   683   all eliminated rules are derived as theorems --> no visible changes ;
   684 
   685 
   686 *** ZF ***
   687 
   688 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
   689 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
   690 as ZF_cs addSIs [equalityI];
   691 
   692 
   693 
   694 New in Isabelle94-7 (November 96)
   695 ---------------------------------
   696 
   697 * allowing negative levels (as offsets) in prlev and choplev;
   698 
   699 * super-linear speedup for large simplifications;
   700 
   701 * FOL, ZF and HOL now use miniscoping: rewriting pushes
   702 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
   703 FAIL); can suppress it using the command Delsimps (ex_simps @
   704 all_simps); De Morgan laws are also now included, by default;
   705 
   706 * improved printing of ==>  :  ~:
   707 
   708 * new object-logic "Sequents" adds linear logic, while replacing LK
   709 and Modal (thanks to Sara Kalvala);
   710 
   711 * HOL/Auth: correctness proofs for authentication protocols;
   712 
   713 * HOL: new auto_tac combines rewriting and classical reasoning (many
   714 examples on HOL/Auth);
   715 
   716 * HOL: new command AddIffs for declaring theorems of the form P=Q to
   717 the rewriter and classical reasoner simultaneously;
   718 
   719 * function uresult no longer returns theorems in "standard" format;
   720 regain previous version by: val uresult = standard o uresult;
   721 
   722 
   723 
   724 New in Isabelle94-6
   725 -------------------
   726 
   727 * oracles -- these establish an interface between Isabelle and trusted
   728 external reasoners, which may deliver results as theorems;
   729 
   730 * proof objects (in particular record all uses of oracles);
   731 
   732 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
   733 
   734 * "constdefs" section in theory files;
   735 
   736 * "primrec" section (HOL) no longer requires names;
   737 
   738 * internal type "tactic" now simply "thm -> thm Sequence.seq";
   739 
   740 
   741 
   742 New in Isabelle94-5
   743 -------------------
   744 
   745 * reduced space requirements;
   746 
   747 * automatic HTML generation from theories;
   748 
   749 * theory files no longer require "..." (quotes) around most types;
   750 
   751 * new examples, including two proofs of the Church-Rosser theorem;
   752 
   753 * non-curried (1994) version of HOL is no longer distributed;
   754 
   755 
   756 
   757 New in Isabelle94-4
   758 -------------------
   759 
   760 * greatly reduced space requirements;
   761 
   762 * theory files (.thy) no longer require \...\ escapes at line breaks;
   763 
   764 * searchable theorem database (see the section "Retrieving theorems" on 
   765 page 8 of the Reference Manual);
   766 
   767 * new examples, including Grabczewski's monumental case study of the
   768 Axiom of Choice;
   769 
   770 * The previous version of HOL renamed to Old_HOL;
   771 
   772 * The new version of HOL (previously called CHOL) uses a curried syntax 
   773 for functions.  Application looks like f a b instead of f(a,b);
   774 
   775 * Mutually recursive inductive definitions finally work in HOL;
   776 
   777 * In ZF, pattern-matching on tuples is now available in all abstractions and
   778 translates to the operator "split";
   779 
   780 
   781 
   782 New in Isabelle94-3
   783 -------------------
   784 
   785 * new infix operator, addss, allowing the classical reasoner to 
   786 perform simplification at each step of its search.  Example:
   787 	fast_tac (cs addss ss)
   788 
   789 * a new logic, CHOL, the same as HOL, but with a curried syntax 
   790 for functions.  Application looks like f a b instead of f(a,b).  Also pairs 
   791 look like (a,b) instead of <a,b>;
   792 
   793 * PLEASE NOTE: CHOL will eventually replace HOL!
   794 
   795 * In CHOL, pattern-matching on tuples is now available in all abstractions.
   796 It translates to the operator "split".  A new theory of integers is available;
   797 
   798 * In ZF, integer numerals now denote two's-complement binary integers.
   799 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
   800 
   801 * Many new examples: I/O automata, Church-Rosser theorem, equivalents 
   802 of the Axiom of Choice;
   803 
   804 
   805 
   806 New in Isabelle94-2
   807 -------------------
   808 
   809 * Significantly faster resolution;  
   810 
   811 * the different sections in a .thy file can now be mixed and repeated
   812 freely;
   813 
   814 * Database of theorems for FOL, HOL and ZF.  New
   815 commands including qed, qed_goal and bind_thm store theorems in the database.
   816 
   817 * Simple database queries: return a named theorem (get_thm) or all theorems of
   818 a given theory (thms_of), or find out what theory a theorem was proved in
   819 (theory_of_thm);
   820 
   821 * Bugs fixed in the inductive definition and datatype packages;
   822 
   823 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
   824 and HOL_dup_cs obsolete;
   825 
   826 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
   827 have been removed;
   828 
   829 * Simpler definition of function space in ZF;
   830 
   831 * new results about cardinal and ordinal arithmetic in ZF;
   832 
   833 * 'subtype' facility in HOL for introducing new types as subsets of existing
   834 types;
   835 
   836 
   837 $Id$