NEWS
author nipkow
Wed Oct 21 15:57:04 1998 +0200 (1998-10-21)
changeset 5709 35b07f8e67b6
parent 5705 56f2030c46c6
child 5710 30f4d3713cbe
permissions -rw-r--r--
Tutorial
     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 HOL TUTORIAL **
   127    Use `isatool doc tutorial' or see Doc/Tutorial.
   128 
   129 * HOL/inductive package reorganized and improved: now supports mutual
   130 definitions such as
   131 
   132   inductive EVEN ODD
   133     intrs
   134       null "0 : EVEN"
   135       oddI "n : EVEN ==> Suc n : ODD"
   136       evenI "n : ODD ==> Suc n : EVEN"
   137 
   138 new theorem list "elims" contains an elimination rule for each of the
   139 recursive sets; inductive definitions now handle disjunctive premises
   140 correctly (also ZF);
   141 
   142 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   143 "mutual_induct" no longer exists - the induction rule is always
   144 contained in "induct";
   145 
   146 
   147 * HOL/datatype package re-implemented and greatly improved: now
   148 supports mutually recursive datatypes such as
   149 
   150   datatype
   151     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
   152             | SUM ('a aexp) ('a aexp)
   153             | DIFF ('a aexp) ('a aexp)
   154             | NUM 'a
   155   and
   156     'a bexp = LESS ('a aexp) ('a aexp)
   157             | AND ('a bexp) ('a bexp)
   158             | OR ('a bexp) ('a bexp)
   159 
   160 as well as indirectly recursive datatypes such as
   161 
   162   datatype
   163     ('a, 'b) term = Var 'a
   164                   | App 'b ((('a, 'b) term) list)
   165 
   166 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
   167 induction on mutually / indirectly recursive datatypes.
   168 
   169 Primrec equations are now stored in theory and can be accessed via
   170 <function_name>.simps.
   171 
   172 INCOMPATIBILITIES:
   173 
   174   - Theories using datatypes must now have theory Datatype as an
   175     ancestor.
   176   - The specific <typename>.induct_tac no longer exists - use the
   177     generic induct_tac instead.
   178   - natE has been renamed to nat.exhaust - use exhaust_tac
   179     instead of res_inst_tac ... natE. Note that the variable
   180     names in nat.exhaust differ from the names in natE, this
   181     may cause some "fragile" proofs to fail.
   182   - The theorems split_<typename>_case and split_<typename>_case_asm
   183     have been renamed to <typename>.split and <typename>.split_asm.
   184   - Since default sorts of type variables are now handled correctly,
   185     some datatype definitions may have to be annotated with explicit
   186     sort constraints.
   187   - Primrec definitions no longer require function name and type
   188     of recursive argument.
   189 
   190 Consider using isatool fixdatatype to adapt your theories and proof
   191 scripts to the new package (backup your sources first!).
   192 
   193 
   194 * HOL/record package: now includes concrete syntax for record types,
   195 terms, updates; still lacks important theorems, like surjective
   196 pairing and split;
   197 
   198 * reorganized the main HOL image: HOL/Integ and String loaded by
   199 default; theory Main includes everything;
   200 
   201 * automatic simplification of integer sums and comparisons, using cancellation;
   202 
   203 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
   204 
   205 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
   206 
   207 * many new identities for unions, intersections, set difference, etc.;
   208 
   209 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
   210 called split_if, split_split, split_sum_case and split_nat_case (to go
   211 with add/delsplits);
   212 
   213 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
   214 (?x::unit) = (); this is made part of the default simpset, which COULD
   215 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
   216 'Delsimprocs [unit_eq_proc];' as last resort); also note that
   217 unit_abs_eta_conv is added in order to counter the effect of
   218 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
   219 %u.f();
   220 
   221 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
   222 makes more sense);
   223 
   224 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   225   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   226   disjointness reasoning but breaking a few old proofs.
   227 
   228 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
   229 to 'converse' from 'inverse' (for compatibility with ZF and some
   230 literature);
   231 
   232 * HOL/recdef can now declare non-recursive functions, with {} supplied as
   233 the well-founded relation;
   234 
   235 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
   236     Compl A.  The "Compl" syntax remains available as input syntax for this
   237     release ONLY.
   238 
   239 * HOL/Update: new theory of function updates:
   240     f(a:=b) == %x. if x=a then b else f x
   241 may also be iterated as in f(a:=b,c:=d,...);
   242 
   243 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
   244 
   245 * HOL/List:
   246   - new function list_update written xs[i:=v] that updates the i-th
   247     list position. May also be iterated as in xs[i:=a,j:=b,...].
   248   - new function `upt' written [i..j(] which generates the list
   249     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
   250     bound write [i..j], which is a shorthand for [i..j+1(].
   251   - new lexicographic orderings and corresponding wellfoundedness theorems.
   252 
   253 * HOL/Arith:
   254   - removed 'pred' (predecessor) function;
   255   - generalized some theorems about n-1;
   256   - many new laws about "div" and "mod";
   257   - new laws about greatest common divisors (see theory ex/Primes);
   258 
   259 * HOL/Relation: renamed the relational operator r^-1 "converse"
   260 instead of "inverse";
   261 
   262 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
   263   of the multiset ordering;
   264 
   265 * directory HOL/Real: a construction of the reals using Dedekind cuts
   266   (not included by default);
   267 
   268 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
   269 
   270 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
   271   programs, i.e. different program variables may have different types.
   272 
   273 * calling (stac rew i) now fails if "rew" has no effect on the goal
   274   [previously, this check worked only if the rewrite rule was unconditional]
   275   Now rew can involve either definitions or equalities (either == or =).
   276 
   277 
   278 *** ZF ***
   279 
   280 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
   281   only the theorems proved on ZF.ML;
   282 
   283 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   284   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   285   disjointness reasoning but breaking a few old proofs.
   286 
   287 * ZF/Update: new theory of function updates
   288     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
   289   may also be iterated as in f(a:=b,c:=d,...);
   290 
   291 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
   292 
   293 * calling (stac rew i) now fails if "rew" has no effect on the goal
   294   [previously, this check worked only if the rewrite rule was unconditional]
   295   Now rew can involve either definitions or equalities (either == or =).
   296 
   297 * case_tac provided for compatibility with HOL
   298     (like the old excluded_middle_tac, but with subgoals swapped)
   299 
   300 
   301 *** Internal programming interfaces ***
   302 
   303 * Pure: several new basic modules made available for general use, see
   304 also src/Pure/README;
   305 
   306 * improved the theory data mechanism to support encapsulation (data
   307 kind name replaced by private Object.kind, acting as authorization
   308 key); new type-safe user interface via functor TheoryDataFun; generic
   309 print_data function becomes basically useless;
   310 
   311 * removed global_names compatibility flag -- all theory declarations
   312 are qualified by default;
   313 
   314 * module Pure/Syntax now offers quote / antiquote translation
   315 functions (useful for Hoare logic etc. with implicit dependencies);
   316 see HOL/ex/Antiquote for an example use;
   317 
   318 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
   319 cterm -> thm;
   320 
   321 * new tactical CHANGED_GOAL for checking that a tactic modifies a
   322 subgoal;
   323 
   324 * Display.print_goals function moved to Locale.print_goals;
   325 
   326 
   327 
   328 New in Isabelle98 (January 1998)
   329 --------------------------------
   330 
   331 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   332 
   333 * changed lexical syntax of terms / types: dots made part of long
   334 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
   335 
   336 * simpset (and claset) reference variable replaced by functions
   337 simpset / simpset_ref;
   338 
   339 * no longer supports theory aliases (via merge) and non-trivial
   340 implicit merge of thms' signatures;
   341 
   342 * most internal names of constants changed due to qualified names;
   343 
   344 * changed Pure/Sequence interface (see Pure/seq.ML);
   345 
   346 
   347 *** General Changes ***
   348 
   349 * hierachically structured name spaces (for consts, types, axms, thms
   350 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
   351 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
   352 isatool fixdots ensures space after dots (e.g. "%x. x"); set
   353 long_names for fully qualified output names; NOTE: ML programs
   354 (special tactics, packages etc.) referring to internal names may have
   355 to be adapted to cope with fully qualified names; in case of severe
   356 backward campatibility problems try setting 'global_names' at compile
   357 time to have enrything declared within a flat name space; one may also
   358 fine tune name declarations in theories via the 'global' and 'local'
   359 section;
   360 
   361 * reimplemented the implicit simpset and claset using the new anytype
   362 data filed in signatures; references simpset:simpset ref etc. are
   363 replaced by functions simpset:unit->simpset and
   364 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
   365 to patch your ML files accordingly;
   366 
   367 * HTML output now includes theory graph data for display with Java
   368 applet or isatool browser; data generated automatically via isatool
   369 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
   370 
   371 * defs may now be conditional; improved rewrite_goals_tac to handle
   372 conditional equations;
   373 
   374 * defs now admits additional type arguments, using TYPE('a) syntax;
   375 
   376 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
   377 creates a new theory node; implicit merge of thms' signatures is
   378 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
   379 transfer:theory->thm->thm in (rare) cases;
   380 
   381 * improved handling of draft signatures / theories; draft thms (and
   382 ctyps, cterms) are automatically promoted to real ones;
   383 
   384 * slightly changed interfaces for oracles: admit many per theory, named
   385 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
   386 
   387 * print_goals: optional output of const types (set show_consts and
   388 show_types);
   389 
   390 * improved output of warnings (###) and errors (***);
   391 
   392 * subgoal_tac displays a warning if the new subgoal has type variables;
   393 
   394 * removed old README and Makefiles;
   395 
   396 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
   397 
   398 * removed obsolete init_pps and init_database;
   399 
   400 * deleted the obsolete tactical STATE, which was declared by
   401     fun STATE tacfun st = tacfun st st;
   402 
   403 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
   404 (which abbreviates $HOME);
   405 
   406 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
   407 use isatool fixseq to adapt your ML programs (this works for fully
   408 qualified references to the Sequence structure only!);
   409 
   410 * use_thy no longer requires writable current directory; it always
   411 reloads .ML *and* .thy file, if either one is out of date;
   412 
   413 
   414 *** Classical Reasoner ***
   415 
   416 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
   417 tactics that use classical reasoning to simplify a subgoal without
   418 splitting it into several subgoals;
   419 
   420 * Safe_tac: like safe_tac but uses the default claset;
   421 
   422 
   423 *** Simplifier ***
   424 
   425 * added simplification meta rules:
   426     (asm_)(full_)simplify: simpset -> thm -> thm;
   427 
   428 * simplifier.ML no longer part of Pure -- has to be loaded by object
   429 logics (again);
   430 
   431 * added prems argument to simplification procedures;
   432 
   433 * HOL, FOL, ZF: added infix function `addsplits':
   434   instead of `<simpset> setloop (split_tac <thms>)'
   435   you can simply write `<simpset> addsplits <thms>'
   436 
   437 
   438 *** Syntax ***
   439 
   440 * TYPE('a) syntax for type reflection terms;
   441 
   442 * no longer handles consts with name "" -- declare as 'syntax' instead;
   443 
   444 * pretty printer: changed order of mixfix annotation preference (again!);
   445 
   446 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
   447 
   448 
   449 *** HOL ***
   450 
   451 * HOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   452   with `addloop' of the simplifier to faciliate case splitting in premises.
   453 
   454 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
   455 
   456 * HOL/Auth: new protocol proofs including some for the Internet
   457   protocol TLS;
   458 
   459 * HOL/Map: new theory of `maps' a la VDM;
   460 
   461 * HOL/simplifier: simplification procedures nat_cancel_sums for
   462 cancelling out common nat summands from =, <, <= (in)equalities, or
   463 differences; simplification procedures nat_cancel_factor for
   464 cancelling common factor from =, <, <= (in)equalities over natural
   465 sums; nat_cancel contains both kinds of procedures, it is installed by
   466 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
   467 
   468 * HOL/simplifier: terms of the form
   469   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
   470   are rewritten to
   471   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
   472   and those of the form
   473   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
   474   are rewritten to
   475   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
   476 
   477 * HOL/datatype
   478   Each datatype `t' now comes with a theorem `split_t_case' of the form
   479 
   480   P(t_case f1 ... fn x) =
   481      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
   482         ...
   483        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
   484      )
   485 
   486   and a theorem `split_t_case_asm' of the form
   487 
   488   P(t_case f1 ... fn x) =
   489     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
   490         ...
   491        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
   492      )
   493   which can be added to a simpset via `addsplits'. The existing theorems
   494   expand_list_case and expand_option_case have been renamed to
   495   split_list_case and split_option_case.
   496 
   497 * HOL/Arithmetic:
   498   - `pred n' is automatically converted to `n-1'.
   499     Users are strongly encouraged not to use `pred' any longer,
   500     because it will disappear altogether at some point.
   501   - Users are strongly encouraged to write "0 < n" rather than
   502     "n ~= 0". Theorems and proof tools have been modified towards this
   503     `standard'.
   504 
   505 * HOL/Lists:
   506   the function "set_of_list" has been renamed "set" (and its theorems too);
   507   the function "nth" now takes its arguments in the reverse order and
   508   has acquired the infix notation "!" as in "xs!n".
   509 
   510 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
   511 
   512 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
   513   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
   514 
   515 * HOL/record: extensible records with schematic structural subtyping
   516 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
   517 still lacks various theorems and concrete record syntax;
   518 
   519 
   520 *** HOLCF ***
   521 
   522 * removed "axioms" and "generated by" sections;
   523 
   524 * replaced "ops" section by extended "consts" section, which is capable of
   525   handling the continuous function space "->" directly;
   526 
   527 * domain package:
   528   . proves theorems immediately and stores them in the theory,
   529   . creates hierachical name space,
   530   . now uses normal mixfix annotations (instead of cinfix...),
   531   . minor changes to some names and values (for consistency),
   532   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
   533   . separator between mutual domain defs: changed "," to "and",
   534   . improved handling of sort constraints;  now they have to
   535     appear on the left-hand side of the equations only;
   536 
   537 * fixed LAM <x,y,zs>.b syntax;
   538 
   539 * added extended adm_tac to simplifier in HOLCF -- can now discharge
   540 adm (%x. P (t x)), where P is chainfinite and t continuous;
   541 
   542 
   543 *** FOL and ZF ***
   544 
   545 * FOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   546   with `addloop' of the simplifier to faciliate case splitting in premises.
   547 
   548 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
   549 in HOL, they strip ALL and --> from proved theorems;
   550 
   551 
   552 
   553 New in Isabelle94-8 (May 1997)
   554 ------------------------------
   555 
   556 *** General Changes ***
   557 
   558 * new utilities to build / run / maintain Isabelle etc. (in parts
   559 still somewhat experimental); old Makefiles etc. still functional;
   560 
   561 * new 'Isabelle System Manual';
   562 
   563 * INSTALL text, together with ./configure and ./build scripts;
   564 
   565 * reimplemented type inference for greater efficiency, better error
   566 messages and clean internal interface;
   567 
   568 * prlim command for dealing with lots of subgoals (an easier way of
   569 setting goals_limit);
   570 
   571 
   572 *** Syntax ***
   573 
   574 * supports alternative (named) syntax tables (parser and pretty
   575 printer); internal interface is provided by add_modesyntax(_i);
   576 
   577 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
   578 be used in conjunction with the Isabelle symbol font; uses the
   579 "symbols" syntax table;
   580 
   581 * added token_translation interface (may translate name tokens in
   582 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
   583 the current print_mode); IMPORTANT: user print translation functions
   584 are responsible for marking newly introduced bounds
   585 (Syntax.mark_boundT);
   586 
   587 * token translations for modes "xterm" and "xterm_color" that display
   588 names in bold, underline etc. or colors (which requires a color
   589 version of xterm);
   590 
   591 * infixes may now be declared with names independent of their syntax;
   592 
   593 * added typed_print_translation (like print_translation, but may
   594 access type of constant);
   595 
   596 
   597 *** Classical Reasoner ***
   598 
   599 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
   600 some limitations.  Blast_tac...
   601   + ignores addss, addbefore, addafter; this restriction is intrinsic
   602   + ignores elimination rules that don't have the correct format
   603 	(the conclusion MUST be a formula variable)
   604   + ignores types, which can make HOL proofs fail
   605   + rules must not require higher-order unification, e.g. apply_type in ZF
   606     [message "Function Var's argument not a bound variable" relates to this]
   607   + its proof strategy is more general but can actually be slower
   608 
   609 * substitution with equality assumptions no longer permutes other
   610 assumptions;
   611 
   612 * minor changes in semantics of addafter (now called addaltern); renamed
   613 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
   614 (and access functions for it);
   615 
   616 * improved combination of classical reasoner and simplifier: 
   617   + functions for handling clasimpsets
   618   + improvement of addss: now the simplifier is called _after_ the
   619     safe steps.
   620   + safe variant of addss called addSss: uses safe simplifications
   621     _during_ the safe steps. It is more complete as it allows multiple 
   622     instantiations of unknowns (e.g. with slow_tac).
   623 
   624 *** Simplifier ***
   625 
   626 * added interface for simplification procedures (functions that
   627 produce *proven* rewrite rules on the fly, depending on current
   628 redex);
   629 
   630 * ordering on terms as parameter (used for ordered rewriting);
   631 
   632 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
   633 
   634 * the solver is now split into a safe and an unsafe part.
   635 This should be invisible for the normal user, except that the
   636 functions setsolver and addsolver have been renamed to setSolver and
   637 addSolver; added safe_asm_full_simp_tac;
   638 
   639 
   640 *** HOL ***
   641 
   642 * a generic induction tactic `induct_tac' which works for all datatypes and
   643 also for type `nat';
   644 
   645 * a generic case distinction tactic `exhaust_tac' which works for all
   646 datatypes and also for type `nat';
   647 
   648 * each datatype comes with a function `size';
   649 
   650 * patterns in case expressions allow tuple patterns as arguments to
   651 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
   652 
   653 * primrec now also works with type nat;
   654 
   655 * recdef: a new declaration form, allows general recursive functions to be
   656 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
   657 
   658 * the constant for negation has been renamed from "not" to "Not" to
   659 harmonize with FOL, ZF, LK, etc.;
   660 
   661 * HOL/ex/LFilter theory of a corecursive "filter" functional for
   662 infinite lists;
   663 
   664 * HOL/Modelcheck demonstrates invocation of model checker oracle;
   665 
   666 * HOL/ex/Ring.thy declares cring_simp, which solves equational
   667 problems in commutative rings, using axiomatic type classes for + and *;
   668 
   669 * more examples in HOL/MiniML and HOL/Auth;
   670 
   671 * more default rewrite rules for quantifiers, union/intersection;
   672 
   673 * a new constant `arbitrary == @x.False';
   674 
   675 * HOLCF/IOA replaces old HOL/IOA;
   676 
   677 * HOLCF changes: derived all rules and arities 
   678   + axiomatic type classes instead of classes 
   679   + typedef instead of faking type definitions
   680   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
   681   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
   682   + eliminated the types void, one, tr
   683   + use unit lift and bool lift (with translations) instead of one and tr
   684   + eliminated blift from Lift3.thy (use Def instead of blift)
   685   all eliminated rules are derived as theorems --> no visible changes ;
   686 
   687 
   688 *** ZF ***
   689 
   690 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
   691 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
   692 as ZF_cs addSIs [equalityI];
   693 
   694 
   695 
   696 New in Isabelle94-7 (November 96)
   697 ---------------------------------
   698 
   699 * allowing negative levels (as offsets) in prlev and choplev;
   700 
   701 * super-linear speedup for large simplifications;
   702 
   703 * FOL, ZF and HOL now use miniscoping: rewriting pushes
   704 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
   705 FAIL); can suppress it using the command Delsimps (ex_simps @
   706 all_simps); De Morgan laws are also now included, by default;
   707 
   708 * improved printing of ==>  :  ~:
   709 
   710 * new object-logic "Sequents" adds linear logic, while replacing LK
   711 and Modal (thanks to Sara Kalvala);
   712 
   713 * HOL/Auth: correctness proofs for authentication protocols;
   714 
   715 * HOL: new auto_tac combines rewriting and classical reasoning (many
   716 examples on HOL/Auth);
   717 
   718 * HOL: new command AddIffs for declaring theorems of the form P=Q to
   719 the rewriter and classical reasoner simultaneously;
   720 
   721 * function uresult no longer returns theorems in "standard" format;
   722 regain previous version by: val uresult = standard o uresult;
   723 
   724 
   725 
   726 New in Isabelle94-6
   727 -------------------
   728 
   729 * oracles -- these establish an interface between Isabelle and trusted
   730 external reasoners, which may deliver results as theorems;
   731 
   732 * proof objects (in particular record all uses of oracles);
   733 
   734 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
   735 
   736 * "constdefs" section in theory files;
   737 
   738 * "primrec" section (HOL) no longer requires names;
   739 
   740 * internal type "tactic" now simply "thm -> thm Sequence.seq";
   741 
   742 
   743 
   744 New in Isabelle94-5
   745 -------------------
   746 
   747 * reduced space requirements;
   748 
   749 * automatic HTML generation from theories;
   750 
   751 * theory files no longer require "..." (quotes) around most types;
   752 
   753 * new examples, including two proofs of the Church-Rosser theorem;
   754 
   755 * non-curried (1994) version of HOL is no longer distributed;
   756 
   757 
   758 
   759 New in Isabelle94-4
   760 -------------------
   761 
   762 * greatly reduced space requirements;
   763 
   764 * theory files (.thy) no longer require \...\ escapes at line breaks;
   765 
   766 * searchable theorem database (see the section "Retrieving theorems" on 
   767 page 8 of the Reference Manual);
   768 
   769 * new examples, including Grabczewski's monumental case study of the
   770 Axiom of Choice;
   771 
   772 * The previous version of HOL renamed to Old_HOL;
   773 
   774 * The new version of HOL (previously called CHOL) uses a curried syntax 
   775 for functions.  Application looks like f a b instead of f(a,b);
   776 
   777 * Mutually recursive inductive definitions finally work in HOL;
   778 
   779 * In ZF, pattern-matching on tuples is now available in all abstractions and
   780 translates to the operator "split";
   781 
   782 
   783 
   784 New in Isabelle94-3
   785 -------------------
   786 
   787 * new infix operator, addss, allowing the classical reasoner to 
   788 perform simplification at each step of its search.  Example:
   789 	fast_tac (cs addss ss)
   790 
   791 * a new logic, CHOL, the same as HOL, but with a curried syntax 
   792 for functions.  Application looks like f a b instead of f(a,b).  Also pairs 
   793 look like (a,b) instead of <a,b>;
   794 
   795 * PLEASE NOTE: CHOL will eventually replace HOL!
   796 
   797 * In CHOL, pattern-matching on tuples is now available in all abstractions.
   798 It translates to the operator "split".  A new theory of integers is available;
   799 
   800 * In ZF, integer numerals now denote two's-complement binary integers.
   801 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
   802 
   803 * Many new examples: I/O automata, Church-Rosser theorem, equivalents 
   804 of the Axiom of Choice;
   805 
   806 
   807 
   808 New in Isabelle94-2
   809 -------------------
   810 
   811 * Significantly faster resolution;  
   812 
   813 * the different sections in a .thy file can now be mixed and repeated
   814 freely;
   815 
   816 * Database of theorems for FOL, HOL and ZF.  New
   817 commands including qed, qed_goal and bind_thm store theorems in the database.
   818 
   819 * Simple database queries: return a named theorem (get_thm) or all theorems of
   820 a given theory (thms_of), or find out what theory a theorem was proved in
   821 (theory_of_thm);
   822 
   823 * Bugs fixed in the inductive definition and datatype packages;
   824 
   825 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
   826 and HOL_dup_cs obsolete;
   827 
   828 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
   829 have been removed;
   830 
   831 * Simpler definition of function space in ZF;
   832 
   833 * new results about cardinal and ordinal arithmetic in ZF;
   834 
   835 * 'subtype' facility in HOL for introducing new types as subsets of existing
   836 types;
   837 
   838 
   839 $Id$