NEWS
author wenzelm
Wed Oct 21 16:04:57 1998 +0200 (1998-10-21)
changeset 5710 30f4d3713cbe
parent 5709 35b07f8e67b6
child 5722 c669e2161b08
permissions -rw-r--r--
tuned;
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle version
     5 ----------------------------
     6 
     7 *** Overview of INCOMPATIBILITIES (see below for more details) ***
     8 
     9 * several changes of proof tools;
    10 
    11 * HOL: new version of inductive and datatype;
    12 
    13 * HOL: major changes to the inductive and datatype packages;
    14 
    15 * HOL: renamed r^-1 to 'converse' from 'inverse'; `inj_onto' is now
    16 called `inj_on';
    17 
    18 * HOL: removed duplicate thms in Arith:
    19   less_imp_add_less  should be replaced by  trans_less_add1
    20   le_imp_add_le      should be replaced by  trans_le_add1
    21 
    22 * HOL: unary - is now overloaded (new type constraints may be required);
    23 
    24 * HOL and ZF: unary minus for integers is now #- instead of #~.  In ZF, 
    25   expressions such as n#-1 must be changed to n#- 1, since #-1 is now taken
    26   as an integer constant.
    27 
    28 * Pure: ML function 'theory_of' replaced by 'theory';
    29 
    30 
    31 *** Proof tools ***
    32 
    33 * Simplifier:
    34   1. 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   2. The simplifier now knows a little bit about nat-arithmetic.
    42 
    43 * Classical reasoner: wrapper mechanism for the classical reasoner now
    44 allows for selected deletion of wrappers, by introduction of names for
    45 wrapper functionals.  This implies that addbefore, addSbefore,
    46 addaltern, and addSaltern now take a pair (name, tactic) as argument,
    47 and that adding two tactics with the same name overwrites the first
    48 one (emitting a warning).
    49   type wrapper = (int -> tactic) -> (int -> tactic)
    50   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
    51   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
    52   delWrapper, delSWrapper: claset *  string            -> claset
    53   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
    54 
    55 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
    56   semantics; addbefore now affects only the unsafe part of step_tac
    57   etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
    58   FAIL, but proofs should be fixable easily, e.g. by replacing
    59   Auto_tac by Force_tac;
    60 
    61 * Classical reasoner: setwrapper to setWrapper and compwrapper to compWrapper; 
    62   added safe wrapper (and access functions for it);
    63 
    64 * HOL/split_all_tac is now much faster and fails if there is nothing
    65 to split.  Existing (fragile) proofs may require adaption because the
    66 order and the names of the automatically generated variables have
    67 changed.  split_all_tac has moved within claset() from unsafe wrappers
    68 to safe wrappers, which means that !!-bound variables are split much
    69 more aggressively, and safe_tac and clarify_tac now split such
    70 variables.  If this splitting is not appropriate, use delSWrapper
    71 "split_all_tac".
    72 
    73 * HOL/Simplifier:
    74 
    75  - Rewrite rules for case distinctions can now be added permanently to
    76    the default simpset using Addsplits just like Addsimps. They can be
    77    removed via Delsplits just like Delsimps. Lower-case versions are
    78    also available.
    79 
    80  - The rule split_if is now part of the default simpset. This means
    81    that the simplifier will eliminate all occurrences of if-then-else
    82    in the conclusion of a goal. To prevent this, you can either remove
    83    split_if completely from the default simpset by `Delsplits
    84    [split_if]' or remove it in a specific call of the simplifier using
    85    `... delsplits [split_if]'.  You can also add/delete other case
    86    splitting rules to/from the default simpset: every datatype
    87    generates suitable rules `split_t_case' and `split_t_case_asm'
    88    (where t is the name of the datatype).
    89 
    90 * Classical reasoner - Simplifier combination: new force_tac (and
    91 derivatives Force_tac, force) combines rewriting and classical
    92 reasoning (and whatever other tools) similarly to auto_tac, but is
    93 aimed to solve the given subgoal completely;
    94 
    95 
    96 *** General ***
    97 
    98 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
    99 and `goalw': the theory is no longer needed as an explicit argument -
   100 the current theory context is used; assumptions are no longer returned
   101 at the ML-level unless one of them starts with ==> or !!; it is
   102 recommended to convert to these new commands using isatool fixgoal
   103 (backup your sources first!);
   104 
   105 * new top-level commands 'thm' and 'thms' for retrieving theorems from
   106 the current theory context, and 'theory' to lookup stored theories;
   107 
   108 * new theory section 'nonterminals' for purely syntactic types;
   109 
   110 * new theory section 'setup' for generic ML setup functions
   111 (e.g. package initialization);
   112 
   113 * the distribution now includes Isabelle icons: see
   114 lib/logo/isabelle-{small,tiny}.xpm;
   115 
   116 * isatool install - install binaries with absolute references to
   117 ISABELLE_HOME/bin;
   118 
   119 * isatool logo -- create instances of the Isabelle logo (as EPS);
   120 
   121 * print mode 'emacs' reserved for Isamode;
   122 
   123 
   124 *** HOL ***
   125 
   126 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
   127 
   128 * HOL/inductive package reorganized and improved: now supports mutual
   129 definitions such as
   130 
   131   inductive EVEN ODD
   132     intrs
   133       null "0 : EVEN"
   134       oddI "n : EVEN ==> Suc n : ODD"
   135       evenI "n : ODD ==> Suc n : EVEN"
   136 
   137 new theorem list "elims" contains an elimination rule for each of the
   138 recursive sets; inductive definitions now handle disjunctive premises
   139 correctly (also ZF);
   140 
   141 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   142 "mutual_induct" no longer exists - the induction rule is always
   143 contained in "induct";
   144 
   145 
   146 * HOL/datatype package re-implemented and greatly improved: now
   147 supports mutually recursive datatypes such as
   148 
   149   datatype
   150     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
   151             | SUM ('a aexp) ('a aexp)
   152             | DIFF ('a aexp) ('a aexp)
   153             | NUM 'a
   154   and
   155     'a bexp = LESS ('a aexp) ('a aexp)
   156             | AND ('a bexp) ('a bexp)
   157             | OR ('a bexp) ('a bexp)
   158 
   159 as well as indirectly recursive datatypes such as
   160 
   161   datatype
   162     ('a, 'b) term = Var 'a
   163                   | App 'b ((('a, 'b) term) list)
   164 
   165 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
   166 induction on mutually / indirectly recursive datatypes.
   167 
   168 Primrec equations are now stored in theory and can be accessed via
   169 <function_name>.simps.
   170 
   171 INCOMPATIBILITIES:
   172 
   173   - Theories using datatypes must now have theory Datatype as an
   174     ancestor.
   175   - The specific <typename>.induct_tac no longer exists - use the
   176     generic induct_tac instead.
   177   - natE has been renamed to nat.exhaust - use exhaust_tac
   178     instead of res_inst_tac ... natE. Note that the variable
   179     names in nat.exhaust differ from the names in natE, this
   180     may cause some "fragile" proofs to fail.
   181   - The theorems split_<typename>_case and split_<typename>_case_asm
   182     have been renamed to <typename>.split and <typename>.split_asm.
   183   - Since default sorts of type variables are now handled correctly,
   184     some datatype definitions may have to be annotated with explicit
   185     sort constraints.
   186   - Primrec definitions no longer require function name and type
   187     of recursive argument.
   188 
   189 Consider using isatool fixdatatype to adapt your theories and proof
   190 scripts to the new package (backup your sources first!).
   191 
   192 
   193 * HOL/record package: now includes concrete syntax for record types,
   194 terms, updates; still lacks important theorems, like surjective
   195 pairing and split;
   196 
   197 * reorganized the main HOL image: HOL/Integ and String loaded by
   198 default; theory Main includes everything;
   199 
   200 * automatic simplification of integer sums and comparisons, using cancellation;
   201 
   202 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
   203 
   204 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
   205 
   206 * many new identities for unions, intersections, set difference, etc.;
   207 
   208 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
   209 called split_if, split_split, split_sum_case and split_nat_case (to go
   210 with add/delsplits);
   211 
   212 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
   213 (?x::unit) = (); this is made part of the default simpset, which COULD
   214 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
   215 'Delsimprocs [unit_eq_proc];' as last resort); also note that
   216 unit_abs_eta_conv is added in order to counter the effect of
   217 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
   218 %u.f();
   219 
   220 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
   221 makes more sense);
   222 
   223 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   224   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   225   disjointness reasoning but breaking a few old proofs.
   226 
   227 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
   228 to 'converse' from 'inverse' (for compatibility with ZF and some
   229 literature);
   230 
   231 * HOL/recdef can now declare non-recursive functions, with {} supplied as
   232 the well-founded relation;
   233 
   234 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
   235     Compl A.  The "Compl" syntax remains available as input syntax for this
   236     release ONLY.
   237 
   238 * HOL/Update: new theory of function updates:
   239     f(a:=b) == %x. if x=a then b else f x
   240 may also be iterated as in f(a:=b,c:=d,...);
   241 
   242 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
   243 
   244 * HOL/List:
   245   - new function list_update written xs[i:=v] that updates the i-th
   246     list position. May also be iterated as in xs[i:=a,j:=b,...].
   247   - new function `upt' written [i..j(] which generates the list
   248     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
   249     bound write [i..j], which is a shorthand for [i..j+1(].
   250   - new lexicographic orderings and corresponding wellfoundedness theorems.
   251 
   252 * HOL/Arith:
   253   - removed 'pred' (predecessor) function;
   254   - generalized some theorems about n-1;
   255   - many new laws about "div" and "mod";
   256   - new laws about greatest common divisors (see theory ex/Primes);
   257 
   258 * HOL/Relation: renamed the relational operator r^-1 "converse"
   259 instead of "inverse";
   260 
   261 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
   262   of the multiset ordering;
   263 
   264 * directory HOL/Real: a construction of the reals using Dedekind cuts
   265   (not included by default);
   266 
   267 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
   268 
   269 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
   270   programs, i.e. different program variables may have different types.
   271 
   272 * calling (stac rew i) now fails if "rew" has no effect on the goal
   273   [previously, this check worked only if the rewrite rule was unconditional]
   274   Now rew can involve either definitions or equalities (either == or =).
   275 
   276 
   277 *** ZF ***
   278 
   279 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
   280   only the theorems proved on ZF.ML;
   281 
   282 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   283   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   284   disjointness reasoning but breaking a few old proofs.
   285 
   286 * ZF/Update: new theory of function updates
   287     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
   288   may also be iterated as in f(a:=b,c:=d,...);
   289 
   290 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
   291 
   292 * calling (stac rew i) now fails if "rew" has no effect on the goal
   293   [previously, this check worked only if the rewrite rule was unconditional]
   294   Now rew can involve either definitions or equalities (either == or =).
   295 
   296 * case_tac provided for compatibility with HOL
   297     (like the old excluded_middle_tac, but with subgoals swapped)
   298 
   299 
   300 *** Internal programming interfaces ***
   301 
   302 * Pure: several new basic modules made available for general use, see
   303 also src/Pure/README;
   304 
   305 * improved the theory data mechanism to support encapsulation (data
   306 kind name replaced by private Object.kind, acting as authorization
   307 key); new type-safe user interface via functor TheoryDataFun; generic
   308 print_data function becomes basically useless;
   309 
   310 * removed global_names compatibility flag -- all theory declarations
   311 are qualified by default;
   312 
   313 * module Pure/Syntax now offers quote / antiquote translation
   314 functions (useful for Hoare logic etc. with implicit dependencies);
   315 see HOL/ex/Antiquote for an example use;
   316 
   317 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
   318 cterm -> thm;
   319 
   320 * new tactical CHANGED_GOAL for checking that a tactic modifies a
   321 subgoal;
   322 
   323 * Display.print_goals function moved to Locale.print_goals;
   324 
   325 
   326 
   327 New in Isabelle98 (January 1998)
   328 --------------------------------
   329 
   330 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   331 
   332 * changed lexical syntax of terms / types: dots made part of long
   333 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
   334 
   335 * simpset (and claset) reference variable replaced by functions
   336 simpset / simpset_ref;
   337 
   338 * no longer supports theory aliases (via merge) and non-trivial
   339 implicit merge of thms' signatures;
   340 
   341 * most internal names of constants changed due to qualified names;
   342 
   343 * changed Pure/Sequence interface (see Pure/seq.ML);
   344 
   345 
   346 *** General Changes ***
   347 
   348 * hierachically structured name spaces (for consts, types, axms, thms
   349 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
   350 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
   351 isatool fixdots ensures space after dots (e.g. "%x. x"); set
   352 long_names for fully qualified output names; NOTE: ML programs
   353 (special tactics, packages etc.) referring to internal names may have
   354 to be adapted to cope with fully qualified names; in case of severe
   355 backward campatibility problems try setting 'global_names' at compile
   356 time to have enrything declared within a flat name space; one may also
   357 fine tune name declarations in theories via the 'global' and 'local'
   358 section;
   359 
   360 * reimplemented the implicit simpset and claset using the new anytype
   361 data filed in signatures; references simpset:simpset ref etc. are
   362 replaced by functions simpset:unit->simpset and
   363 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
   364 to patch your ML files accordingly;
   365 
   366 * HTML output now includes theory graph data for display with Java
   367 applet or isatool browser; data generated automatically via isatool
   368 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
   369 
   370 * defs may now be conditional; improved rewrite_goals_tac to handle
   371 conditional equations;
   372 
   373 * defs now admits additional type arguments, using TYPE('a) syntax;
   374 
   375 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
   376 creates a new theory node; implicit merge of thms' signatures is
   377 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
   378 transfer:theory->thm->thm in (rare) cases;
   379 
   380 * improved handling of draft signatures / theories; draft thms (and
   381 ctyps, cterms) are automatically promoted to real ones;
   382 
   383 * slightly changed interfaces for oracles: admit many per theory, named
   384 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
   385 
   386 * print_goals: optional output of const types (set show_consts and
   387 show_types);
   388 
   389 * improved output of warnings (###) and errors (***);
   390 
   391 * subgoal_tac displays a warning if the new subgoal has type variables;
   392 
   393 * removed old README and Makefiles;
   394 
   395 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
   396 
   397 * removed obsolete init_pps and init_database;
   398 
   399 * deleted the obsolete tactical STATE, which was declared by
   400     fun STATE tacfun st = tacfun st st;
   401 
   402 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
   403 (which abbreviates $HOME);
   404 
   405 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
   406 use isatool fixseq to adapt your ML programs (this works for fully
   407 qualified references to the Sequence structure only!);
   408 
   409 * use_thy no longer requires writable current directory; it always
   410 reloads .ML *and* .thy file, if either one is out of date;
   411 
   412 
   413 *** Classical Reasoner ***
   414 
   415 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
   416 tactics that use classical reasoning to simplify a subgoal without
   417 splitting it into several subgoals;
   418 
   419 * Safe_tac: like safe_tac but uses the default claset;
   420 
   421 
   422 *** Simplifier ***
   423 
   424 * added simplification meta rules:
   425     (asm_)(full_)simplify: simpset -> thm -> thm;
   426 
   427 * simplifier.ML no longer part of Pure -- has to be loaded by object
   428 logics (again);
   429 
   430 * added prems argument to simplification procedures;
   431 
   432 * HOL, FOL, ZF: added infix function `addsplits':
   433   instead of `<simpset> setloop (split_tac <thms>)'
   434   you can simply write `<simpset> addsplits <thms>'
   435 
   436 
   437 *** Syntax ***
   438 
   439 * TYPE('a) syntax for type reflection terms;
   440 
   441 * no longer handles consts with name "" -- declare as 'syntax' instead;
   442 
   443 * pretty printer: changed order of mixfix annotation preference (again!);
   444 
   445 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
   446 
   447 
   448 *** HOL ***
   449 
   450 * HOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   451   with `addloop' of the simplifier to faciliate case splitting in premises.
   452 
   453 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
   454 
   455 * HOL/Auth: new protocol proofs including some for the Internet
   456   protocol TLS;
   457 
   458 * HOL/Map: new theory of `maps' a la VDM;
   459 
   460 * HOL/simplifier: simplification procedures nat_cancel_sums for
   461 cancelling out common nat summands from =, <, <= (in)equalities, or
   462 differences; simplification procedures nat_cancel_factor for
   463 cancelling common factor from =, <, <= (in)equalities over natural
   464 sums; nat_cancel contains both kinds of procedures, it is installed by
   465 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
   466 
   467 * HOL/simplifier: terms of the form
   468   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
   469   are rewritten to
   470   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
   471   and those of the form
   472   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
   473   are rewritten to
   474   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
   475 
   476 * HOL/datatype
   477   Each datatype `t' now comes with a theorem `split_t_case' of the form
   478 
   479   P(t_case f1 ... fn x) =
   480      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
   481         ...
   482        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
   483      )
   484 
   485   and a theorem `split_t_case_asm' of the form
   486 
   487   P(t_case f1 ... fn x) =
   488     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
   489         ...
   490        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
   491      )
   492   which can be added to a simpset via `addsplits'. The existing theorems
   493   expand_list_case and expand_option_case have been renamed to
   494   split_list_case and split_option_case.
   495 
   496 * HOL/Arithmetic:
   497   - `pred n' is automatically converted to `n-1'.
   498     Users are strongly encouraged not to use `pred' any longer,
   499     because it will disappear altogether at some point.
   500   - Users are strongly encouraged to write "0 < n" rather than
   501     "n ~= 0". Theorems and proof tools have been modified towards this
   502     `standard'.
   503 
   504 * HOL/Lists:
   505   the function "set_of_list" has been renamed "set" (and its theorems too);
   506   the function "nth" now takes its arguments in the reverse order and
   507   has acquired the infix notation "!" as in "xs!n".
   508 
   509 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
   510 
   511 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
   512   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
   513 
   514 * HOL/record: extensible records with schematic structural subtyping
   515 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
   516 still lacks various theorems and concrete record syntax;
   517 
   518 
   519 *** HOLCF ***
   520 
   521 * removed "axioms" and "generated by" sections;
   522 
   523 * replaced "ops" section by extended "consts" section, which is capable of
   524   handling the continuous function space "->" directly;
   525 
   526 * domain package:
   527   . proves theorems immediately and stores them in the theory,
   528   . creates hierachical name space,
   529   . now uses normal mixfix annotations (instead of cinfix...),
   530   . minor changes to some names and values (for consistency),
   531   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
   532   . separator between mutual domain defs: changed "," to "and",
   533   . improved handling of sort constraints;  now they have to
   534     appear on the left-hand side of the equations only;
   535 
   536 * fixed LAM <x,y,zs>.b syntax;
   537 
   538 * added extended adm_tac to simplifier in HOLCF -- can now discharge
   539 adm (%x. P (t x)), where P is chainfinite and t continuous;
   540 
   541 
   542 *** FOL and ZF ***
   543 
   544 * FOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   545   with `addloop' of the simplifier to faciliate case splitting in premises.
   546 
   547 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
   548 in HOL, they strip ALL and --> from proved theorems;
   549 
   550 
   551 
   552 New in Isabelle94-8 (May 1997)
   553 ------------------------------
   554 
   555 *** General Changes ***
   556 
   557 * new utilities to build / run / maintain Isabelle etc. (in parts
   558 still somewhat experimental); old Makefiles etc. still functional;
   559 
   560 * new 'Isabelle System Manual';
   561 
   562 * INSTALL text, together with ./configure and ./build scripts;
   563 
   564 * reimplemented type inference for greater efficiency, better error
   565 messages and clean internal interface;
   566 
   567 * prlim command for dealing with lots of subgoals (an easier way of
   568 setting goals_limit);
   569 
   570 
   571 *** Syntax ***
   572 
   573 * supports alternative (named) syntax tables (parser and pretty
   574 printer); internal interface is provided by add_modesyntax(_i);
   575 
   576 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
   577 be used in conjunction with the Isabelle symbol font; uses the
   578 "symbols" syntax table;
   579 
   580 * added token_translation interface (may translate name tokens in
   581 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
   582 the current print_mode); IMPORTANT: user print translation functions
   583 are responsible for marking newly introduced bounds
   584 (Syntax.mark_boundT);
   585 
   586 * token translations for modes "xterm" and "xterm_color" that display
   587 names in bold, underline etc. or colors (which requires a color
   588 version of xterm);
   589 
   590 * infixes may now be declared with names independent of their syntax;
   591 
   592 * added typed_print_translation (like print_translation, but may
   593 access type of constant);
   594 
   595 
   596 *** Classical Reasoner ***
   597 
   598 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
   599 some limitations.  Blast_tac...
   600   + ignores addss, addbefore, addafter; this restriction is intrinsic
   601   + ignores elimination rules that don't have the correct format
   602 	(the conclusion MUST be a formula variable)
   603   + ignores types, which can make HOL proofs fail
   604   + rules must not require higher-order unification, e.g. apply_type in ZF
   605     [message "Function Var's argument not a bound variable" relates to this]
   606   + its proof strategy is more general but can actually be slower
   607 
   608 * substitution with equality assumptions no longer permutes other
   609 assumptions;
   610 
   611 * minor changes in semantics of addafter (now called addaltern); renamed
   612 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
   613 (and access functions for it);
   614 
   615 * improved combination of classical reasoner and simplifier: 
   616   + functions for handling clasimpsets
   617   + improvement of addss: now the simplifier is called _after_ the
   618     safe steps.
   619   + safe variant of addss called addSss: uses safe simplifications
   620     _during_ the safe steps. It is more complete as it allows multiple 
   621     instantiations of unknowns (e.g. with slow_tac).
   622 
   623 *** Simplifier ***
   624 
   625 * added interface for simplification procedures (functions that
   626 produce *proven* rewrite rules on the fly, depending on current
   627 redex);
   628 
   629 * ordering on terms as parameter (used for ordered rewriting);
   630 
   631 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
   632 
   633 * the solver is now split into a safe and an unsafe part.
   634 This should be invisible for the normal user, except that the
   635 functions setsolver and addsolver have been renamed to setSolver and
   636 addSolver; added safe_asm_full_simp_tac;
   637 
   638 
   639 *** HOL ***
   640 
   641 * a generic induction tactic `induct_tac' which works for all datatypes and
   642 also for type `nat';
   643 
   644 * a generic case distinction tactic `exhaust_tac' which works for all
   645 datatypes and also for type `nat';
   646 
   647 * each datatype comes with a function `size';
   648 
   649 * patterns in case expressions allow tuple patterns as arguments to
   650 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
   651 
   652 * primrec now also works with type nat;
   653 
   654 * recdef: a new declaration form, allows general recursive functions to be
   655 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
   656 
   657 * the constant for negation has been renamed from "not" to "Not" to
   658 harmonize with FOL, ZF, LK, etc.;
   659 
   660 * HOL/ex/LFilter theory of a corecursive "filter" functional for
   661 infinite lists;
   662 
   663 * HOL/Modelcheck demonstrates invocation of model checker oracle;
   664 
   665 * HOL/ex/Ring.thy declares cring_simp, which solves equational
   666 problems in commutative rings, using axiomatic type classes for + and *;
   667 
   668 * more examples in HOL/MiniML and HOL/Auth;
   669 
   670 * more default rewrite rules for quantifiers, union/intersection;
   671 
   672 * a new constant `arbitrary == @x.False';
   673 
   674 * HOLCF/IOA replaces old HOL/IOA;
   675 
   676 * HOLCF changes: derived all rules and arities 
   677   + axiomatic type classes instead of classes 
   678   + typedef instead of faking type definitions
   679   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
   680   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
   681   + eliminated the types void, one, tr
   682   + use unit lift and bool lift (with translations) instead of one and tr
   683   + eliminated blift from Lift3.thy (use Def instead of blift)
   684   all eliminated rules are derived as theorems --> no visible changes ;
   685 
   686 
   687 *** ZF ***
   688 
   689 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
   690 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
   691 as ZF_cs addSIs [equalityI];
   692 
   693 
   694 
   695 New in Isabelle94-7 (November 96)
   696 ---------------------------------
   697 
   698 * allowing negative levels (as offsets) in prlev and choplev;
   699 
   700 * super-linear speedup for large simplifications;
   701 
   702 * FOL, ZF and HOL now use miniscoping: rewriting pushes
   703 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
   704 FAIL); can suppress it using the command Delsimps (ex_simps @
   705 all_simps); De Morgan laws are also now included, by default;
   706 
   707 * improved printing of ==>  :  ~:
   708 
   709 * new object-logic "Sequents" adds linear logic, while replacing LK
   710 and Modal (thanks to Sara Kalvala);
   711 
   712 * HOL/Auth: correctness proofs for authentication protocols;
   713 
   714 * HOL: new auto_tac combines rewriting and classical reasoning (many
   715 examples on HOL/Auth);
   716 
   717 * HOL: new command AddIffs for declaring theorems of the form P=Q to
   718 the rewriter and classical reasoner simultaneously;
   719 
   720 * function uresult no longer returns theorems in "standard" format;
   721 regain previous version by: val uresult = standard o uresult;
   722 
   723 
   724 
   725 New in Isabelle94-6
   726 -------------------
   727 
   728 * oracles -- these establish an interface between Isabelle and trusted
   729 external reasoners, which may deliver results as theorems;
   730 
   731 * proof objects (in particular record all uses of oracles);
   732 
   733 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
   734 
   735 * "constdefs" section in theory files;
   736 
   737 * "primrec" section (HOL) no longer requires names;
   738 
   739 * internal type "tactic" now simply "thm -> thm Sequence.seq";
   740 
   741 
   742 
   743 New in Isabelle94-5
   744 -------------------
   745 
   746 * reduced space requirements;
   747 
   748 * automatic HTML generation from theories;
   749 
   750 * theory files no longer require "..." (quotes) around most types;
   751 
   752 * new examples, including two proofs of the Church-Rosser theorem;
   753 
   754 * non-curried (1994) version of HOL is no longer distributed;
   755 
   756 
   757 
   758 New in Isabelle94-4
   759 -------------------
   760 
   761 * greatly reduced space requirements;
   762 
   763 * theory files (.thy) no longer require \...\ escapes at line breaks;
   764 
   765 * searchable theorem database (see the section "Retrieving theorems" on 
   766 page 8 of the Reference Manual);
   767 
   768 * new examples, including Grabczewski's monumental case study of the
   769 Axiom of Choice;
   770 
   771 * The previous version of HOL renamed to Old_HOL;
   772 
   773 * The new version of HOL (previously called CHOL) uses a curried syntax 
   774 for functions.  Application looks like f a b instead of f(a,b);
   775 
   776 * Mutually recursive inductive definitions finally work in HOL;
   777 
   778 * In ZF, pattern-matching on tuples is now available in all abstractions and
   779 translates to the operator "split";
   780 
   781 
   782 
   783 New in Isabelle94-3
   784 -------------------
   785 
   786 * new infix operator, addss, allowing the classical reasoner to 
   787 perform simplification at each step of its search.  Example:
   788 	fast_tac (cs addss ss)
   789 
   790 * a new logic, CHOL, the same as HOL, but with a curried syntax 
   791 for functions.  Application looks like f a b instead of f(a,b).  Also pairs 
   792 look like (a,b) instead of <a,b>;
   793 
   794 * PLEASE NOTE: CHOL will eventually replace HOL!
   795 
   796 * In CHOL, pattern-matching on tuples is now available in all abstractions.
   797 It translates to the operator "split".  A new theory of integers is available;
   798 
   799 * In ZF, integer numerals now denote two's-complement binary integers.
   800 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
   801 
   802 * Many new examples: I/O automata, Church-Rosser theorem, equivalents 
   803 of the Axiom of Choice;
   804 
   805 
   806 
   807 New in Isabelle94-2
   808 -------------------
   809 
   810 * Significantly faster resolution;  
   811 
   812 * the different sections in a .thy file can now be mixed and repeated
   813 freely;
   814 
   815 * Database of theorems for FOL, HOL and ZF.  New
   816 commands including qed, qed_goal and bind_thm store theorems in the database.
   817 
   818 * Simple database queries: return a named theorem (get_thm) or all theorems of
   819 a given theory (thms_of), or find out what theory a theorem was proved in
   820 (theory_of_thm);
   821 
   822 * Bugs fixed in the inductive definition and datatype packages;
   823 
   824 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
   825 and HOL_dup_cs obsolete;
   826 
   827 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
   828 have been removed;
   829 
   830 * Simpler definition of function space in ZF;
   831 
   832 * new results about cardinal and ordinal arithmetic in ZF;
   833 
   834 * 'subtype' facility in HOL for introducing new types as subsets of existing
   835 types;
   836 
   837 
   838 $Id$