NEWS
author paulson
Thu Sep 10 18:07:06 1998 +0200 (1998-09-10)
changeset 5475 410172655d64
parent 5428 5a6c4f666a25
child 5490 85855f65d0c6
permissions -rw-r--r--
equals0D
     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 * Pure: ML function 'theory_of' replaced by 'theory';
    24 
    25 
    26 *** Proof tools ***
    27 
    28 * Simplifier: Asm_full_simp_tac is now more aggressive.
    29   1. It will sometimes reorient premises if that increases their power to
    30      simplify.
    31   2. It does no longer proceed strictly from left to right but may also
    32      rotate premises to achieve further simplification.
    33   For compatibility reasons there is now Asm_lr_simp_tac which is like the
    34   old Asm_full_simp_tac in that it does not rotate premises.
    35 
    36 * Classical reasoner: wrapper mechanism for the classical reasoner now
    37 allows for selected deletion of wrappers, by introduction of names for
    38 wrapper functionals.  This implies that addbefore, addSbefore,
    39 addaltern, and addSaltern now take a pair (name, tactic) as argument,
    40 and that adding two tactics with the same name overwrites the first
    41 one (emitting a warning).
    42   type wrapper = (int -> tactic) -> (int -> tactic)
    43   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
    44   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
    45   delWrapper, delSWrapper: claset *  string            -> claset
    46   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
    47 
    48 * HOL/split_all_tac is now much faster and fails if there is nothing
    49 to split.  Existing (fragile) proofs may require adaption because the
    50 order and the names of the automatically generated variables have
    51 changed.  split_all_tac has moved within claset() from unsafe wrappers
    52 to safe wrappers, which means that !!-bound variables are split much
    53 more aggressively, and safe_tac and clarify_tac now split such
    54 variables.  If this splitting is not appropriate, use delSWrapper
    55 "split_all_tac".
    56 
    57 * HOL/Simplifier:
    58 
    59  - Rewrite rules for case distinctions can now be added permanently to
    60    the default simpset using Addsplits just like Addsimps. They can be
    61    removed via Delsplits just like Delsimps. Lower-case versions are
    62    also available.
    63 
    64  - The rule split_if is now part of the default simpset. This means
    65    that the simplifier will eliminate all occurrences of if-then-else
    66    in the conclusion of a goal. To prevent this, you can either remove
    67    split_if completely from the default simpset by `Delsplits
    68    [split_if]' or remove it in a specific call of the simplifier using
    69    `... delsplits [split_if]'.  You can also add/delete other case
    70    splitting rules to/from the default simpset: every datatype
    71    generates suitable rules `split_t_case' and `split_t_case_asm'
    72    (where t is the name of the datatype).
    73 
    74 * Classical reasoner - Simplifier combination: new force_tac (and
    75 derivatives Force_tac, force) combines rewriting and classical
    76 reasoning (and whatever other tools) similarly to auto_tac, but is
    77 aimed to solve the given subgoal completely;
    78 
    79 
    80 *** General ***
    81 
    82 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
    83 and `goalw': the theory is no longer needed as an explicit argument -
    84 the current theory context is used; assumptions are no longer returned
    85 at the ML-level unless one of them starts with ==> or !!; it is
    86 recommended to convert to these new commands using isatool fixgoal
    87 (backup your sources first!);
    88 
    89 * new top-level commands 'thm' and 'thms' for retrieving theorems from
    90 the current theory context, and 'theory' to lookup stored theories;
    91 
    92 * new theory section 'nonterminals' for purely syntactic types;
    93 
    94 * new theory section 'setup' for generic ML setup functions
    95 (e.g. package initialization);
    96 
    97 * the distribution now includes Isabelle icons: see
    98 lib/logo/isabelle-{small,tiny}.xpm;
    99 
   100 * isatool install - install binaries with absolute references to
   101 ISABELLE_HOME/bin;
   102 
   103 * print mode 'emacs' reserved for Isamode;
   104 
   105 
   106 *** HOL ***
   107 
   108 * HOL/inductive package reorganized and improved: now supports mutual
   109 definitions such as
   110 
   111   inductive EVEN ODD
   112     intrs
   113       null "0 : EVEN"
   114       oddI "n : EVEN ==> Suc n : ODD"
   115       evenI "n : ODD ==> Suc n : EVEN"
   116 
   117 new theorem list "elims" contains an elimination rule for each of the
   118 recursive sets; inductive definitions now handle disjunctive premises
   119 correctly (also ZF);
   120 
   121 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   122 "mutual_induct" no longer exists - the induction rule is always
   123 contained in "induct";
   124 
   125 
   126 * HOL/datatype package re-implemented and greatly improved: now
   127 supports mutually recursive datatypes such as
   128 
   129   datatype
   130     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
   131             | SUM ('a aexp) ('a aexp)
   132             | DIFF ('a aexp) ('a aexp)
   133             | NUM 'a
   134   and
   135     'a bexp = LESS ('a aexp) ('a aexp)
   136             | AND ('a bexp) ('a bexp)
   137             | OR ('a bexp) ('a bexp)
   138 
   139 as well as indirectly recursive datatypes such as
   140 
   141   datatype
   142     ('a, 'b) term = Var 'a
   143                   | App 'b ((('a, 'b) term) list)
   144 
   145 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
   146 induction on mutually / indirectly recursive datatypes.
   147 
   148 Primrec equations are now stored in theory and can be accessed via
   149 <function_name>.simps.
   150 
   151 INCOMPATIBILITIES:
   152 
   153   - Theories using datatypes must now have theory Datatype as an
   154     ancestor.
   155   - The specific <typename>.induct_tac no longer exists - use the
   156     generic induct_tac instead.
   157   - natE has been renamed to nat.exhaust - use exhaust_tac
   158     instead of res_inst_tac ... natE. Note that the variable
   159     names in nat.exhaust differ from the names in natE, this
   160     may cause some "fragile" proofs to fail.
   161   - The theorems split_<typename>_case and split_<typename>_case_asm
   162     have been renamed to <typename>.split and <typename>.split_asm.
   163   - Since default sorts of type variables are now handled correctly,
   164     some datatype definitions may have to be annotated with explicit
   165     sort constraints.
   166   - Primrec definitions no longer require function name and type
   167     of recursive argument.
   168 
   169 Consider using isatool fixdatatype to adapt your theories and proof
   170 scripts to the new package (backup your sources first!).
   171 
   172 
   173 * HOL/record package: now includes concrete syntax for record types,
   174 terms, updates; still lacks important theorems, like surjective
   175 pairing and split;
   176 
   177 * reorganized the main HOL image: HOL/Integ and String loaded by
   178 default; theory Main includes everything;
   179 
   180 * added option_map_eq_Some to the default simpset claset;
   181 
   182 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
   183 
   184 * many new identities for unions, intersections, set difference, etc.;
   185 
   186 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
   187 called split_if, split_split, split_sum_case and split_nat_case (to go
   188 with add/delsplits);
   189 
   190 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
   191 (?x::unit) = (); this is made part of the default simpset, which COULD
   192 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
   193 'Delsimprocs [unit_eq_proc];' as last resort); also note that
   194 unit_abs_eta_conv is added in order to counter the effect of
   195 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
   196 %u.f();
   197 
   198 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
   199 makes more sense);
   200 
   201 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   202   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   203   disjointness reasoning but breaking a few old proofs.
   204 
   205 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
   206 to 'converse' from 'inverse' (for compatibility with ZF and some
   207 literature);
   208 
   209 * HOL/recdef can now declare non-recursive functions, with {} supplied as
   210 the well-founded relation;
   211 
   212 * HOL/Update: new theory of function updates:
   213     f(a:=b) == %x. if x=a then b else f x
   214 may also be iterated as in f(a:=b,c:=d,...);
   215 
   216 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
   217 
   218 * HOL/List:
   219   - new function list_update written xs[i:=v] that updates the i-th
   220     list position. May also be iterated as in xs[i:=a,j:=b,...].
   221   - new function `upt' written [i..j(] which generates the list
   222     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
   223     bound write [i..j], which is a shorthand for [i..j+1(].
   224   - new lexicographic orderings and corresponding wellfoundedness theorems.
   225 
   226 * HOL/Arith:
   227   - removed 'pred' (predecessor) function;
   228   - generalized some theorems about n-1;
   229   - many new laws about "div" and "mod";
   230   - new laws about greatest common divisors (see theory ex/Primes);
   231 
   232 * HOL/Relation: renamed the relational operator r^-1 "converse"
   233 instead of "inverse";
   234 
   235 * directory HOL/Real: a construction of the reals using Dedekind cuts
   236 (not included by default);
   237 
   238 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
   239 
   240 * calling (stac rew i) now fails if "rew" has no effect on the goal
   241   [previously, this check worked only if the rewrite rule was unconditional]
   242   Now rew can involve either definitions or equalities (either == or =).
   243 
   244 
   245 *** ZF ***
   246 
   247 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
   248   only the theorems proved on ZF.ML;
   249 
   250 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   251   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   252   disjointness reasoning but breaking a few old proofs.
   253 
   254 * ZF/Update: new theory of function updates
   255     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
   256   may also be iterated as in f(a:=b,c:=d,...);
   257 
   258 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
   259 
   260 * calling (stac rew i) now fails if "rew" has no effect on the goal
   261   [previously, this check worked only if the rewrite rule was unconditional]
   262   Now rew can involve either definitions or equalities (either == or =).
   263 
   264 * case_tac provided for compatibility with HOL
   265     (like the old excluded_middle_tac, but with subgoals swapped)
   266 
   267 
   268 *** Internal programming interfaces ***
   269 
   270 * Pure: several new basic modules made available for general use, see
   271 also src/Pure/README;
   272 
   273 * improved the theory data mechanism to support encapsulation (data
   274 kind name replaced by private Object.kind, acting as authorization
   275 key); new type-safe user interface via functor TheoryDataFun; generic
   276 print_data function becomes basically useless;
   277 
   278 * removed global_names compatibility flag -- all theory declarations
   279 are qualified by default;
   280 
   281 * module Pure/Syntax now offers quote / antiquote translation
   282 functions (useful for Hoare logic etc. with implicit dependencies);
   283 see HOL/ex/Antiquote for an example use;
   284 
   285 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
   286 cterm -> thm;
   287 
   288 * new tactical CHANGED_GOAL for checking that a tactic modifies a
   289 subgoal;
   290 
   291 * Display.print_goals function moved to Locale.print_goals;
   292 
   293 
   294 
   295 New in Isabelle98 (January 1998)
   296 --------------------------------
   297 
   298 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   299 
   300 * changed lexical syntax of terms / types: dots made part of long
   301 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
   302 
   303 * simpset (and claset) reference variable replaced by functions
   304 simpset / simpset_ref;
   305 
   306 * no longer supports theory aliases (via merge) and non-trivial
   307 implicit merge of thms' signatures;
   308 
   309 * most internal names of constants changed due to qualified names;
   310 
   311 * changed Pure/Sequence interface (see Pure/seq.ML);
   312 
   313 
   314 *** General Changes ***
   315 
   316 * hierachically structured name spaces (for consts, types, axms, thms
   317 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
   318 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
   319 isatool fixdots ensures space after dots (e.g. "%x. x"); set
   320 long_names for fully qualified output names; NOTE: ML programs
   321 (special tactics, packages etc.) referring to internal names may have
   322 to be adapted to cope with fully qualified names; in case of severe
   323 backward campatibility problems try setting 'global_names' at compile
   324 time to have enrything declared within a flat name space; one may also
   325 fine tune name declarations in theories via the 'global' and 'local'
   326 section;
   327 
   328 * reimplemented the implicit simpset and claset using the new anytype
   329 data filed in signatures; references simpset:simpset ref etc. are
   330 replaced by functions simpset:unit->simpset and
   331 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
   332 to patch your ML files accordingly;
   333 
   334 * HTML output now includes theory graph data for display with Java
   335 applet or isatool browser; data generated automatically via isatool
   336 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
   337 
   338 * defs may now be conditional; improved rewrite_goals_tac to handle
   339 conditional equations;
   340 
   341 * defs now admits additional type arguments, using TYPE('a) syntax;
   342 
   343 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
   344 creates a new theory node; implicit merge of thms' signatures is
   345 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
   346 transfer:theory->thm->thm in (rare) cases;
   347 
   348 * improved handling of draft signatures / theories; draft thms (and
   349 ctyps, cterms) are automatically promoted to real ones;
   350 
   351 * slightly changed interfaces for oracles: admit many per theory, named
   352 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
   353 
   354 * print_goals: optional output of const types (set show_consts and
   355 show_types);
   356 
   357 * improved output of warnings (###) and errors (***);
   358 
   359 * subgoal_tac displays a warning if the new subgoal has type variables;
   360 
   361 * removed old README and Makefiles;
   362 
   363 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
   364 
   365 * removed obsolete init_pps and init_database;
   366 
   367 * deleted the obsolete tactical STATE, which was declared by
   368     fun STATE tacfun st = tacfun st st;
   369 
   370 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
   371 (which abbreviates $HOME);
   372 
   373 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
   374 use isatool fixseq to adapt your ML programs (this works for fully
   375 qualified references to the Sequence structure only!);
   376 
   377 * use_thy no longer requires writable current directory; it always
   378 reloads .ML *and* .thy file, if either one is out of date;
   379 
   380 
   381 *** Classical Reasoner ***
   382 
   383 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
   384 tactics that use classical reasoning to simplify a subgoal without
   385 splitting it into several subgoals;
   386 
   387 * Safe_tac: like safe_tac but uses the default claset;
   388 
   389 
   390 *** Simplifier ***
   391 
   392 * added simplification meta rules:
   393     (asm_)(full_)simplify: simpset -> thm -> thm;
   394 
   395 * simplifier.ML no longer part of Pure -- has to be loaded by object
   396 logics (again);
   397 
   398 * added prems argument to simplification procedures;
   399 
   400 * HOL, FOL, ZF: added infix function `addsplits':
   401   instead of `<simpset> setloop (split_tac <thms>)'
   402   you can simply write `<simpset> addsplits <thms>'
   403 
   404 
   405 *** Syntax ***
   406 
   407 * TYPE('a) syntax for type reflection terms;
   408 
   409 * no longer handles consts with name "" -- declare as 'syntax' instead;
   410 
   411 * pretty printer: changed order of mixfix annotation preference (again!);
   412 
   413 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
   414 
   415 
   416 *** HOL ***
   417 
   418 * HOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   419   with `addloop' of the simplifier to faciliate case splitting in premises.
   420 
   421 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
   422 
   423 * HOL/Auth: new protocol proofs including some for the Internet
   424   protocol TLS;
   425 
   426 * HOL/Map: new theory of `maps' a la VDM;
   427 
   428 * HOL/simplifier: simplification procedures nat_cancel_sums for
   429 cancelling out common nat summands from =, <, <= (in)equalities, or
   430 differences; simplification procedures nat_cancel_factor for
   431 cancelling common factor from =, <, <= (in)equalities over natural
   432 sums; nat_cancel contains both kinds of procedures, it is installed by
   433 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
   434 
   435 * HOL/simplifier: terms of the form
   436   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
   437   are rewritten to
   438   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
   439   and those of the form
   440   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
   441   are rewritten to
   442   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
   443 
   444 * HOL/datatype
   445   Each datatype `t' now comes with a theorem `split_t_case' of the form
   446 
   447   P(t_case f1 ... fn x) =
   448      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
   449         ...
   450        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
   451      )
   452 
   453   and a theorem `split_t_case_asm' of the form
   454 
   455   P(t_case f1 ... fn x) =
   456     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
   457         ...
   458        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
   459      )
   460   which can be added to a simpset via `addsplits'. The existing theorems
   461   expand_list_case and expand_option_case have been renamed to
   462   split_list_case and split_option_case.
   463 
   464 * HOL/Arithmetic:
   465   - `pred n' is automatically converted to `n-1'.
   466     Users are strongly encouraged not to use `pred' any longer,
   467     because it will disappear altogether at some point.
   468   - Users are strongly encouraged to write "0 < n" rather than
   469     "n ~= 0". Theorems and proof tools have been modified towards this
   470     `standard'.
   471 
   472 * HOL/Lists:
   473   the function "set_of_list" has been renamed "set" (and its theorems too);
   474   the function "nth" now takes its arguments in the reverse order and
   475   has acquired the infix notation "!" as in "xs!n".
   476 
   477 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
   478 
   479 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
   480   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
   481 
   482 * HOL/record: extensible records with schematic structural subtyping
   483 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
   484 still lacks various theorems and concrete record syntax;
   485 
   486 
   487 *** HOLCF ***
   488 
   489 * removed "axioms" and "generated by" sections;
   490 
   491 * replaced "ops" section by extended "consts" section, which is capable of
   492   handling the continuous function space "->" directly;
   493 
   494 * domain package:
   495   . proves theorems immediately and stores them in the theory,
   496   . creates hierachical name space,
   497   . now uses normal mixfix annotations (instead of cinfix...),
   498   . minor changes to some names and values (for consistency),
   499   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
   500   . separator between mutual domain defs: changed "," to "and",
   501   . improved handling of sort constraints;  now they have to
   502     appear on the left-hand side of the equations only;
   503 
   504 * fixed LAM <x,y,zs>.b syntax;
   505 
   506 * added extended adm_tac to simplifier in HOLCF -- can now discharge
   507 adm (%x. P (t x)), where P is chainfinite and t continuous;
   508 
   509 
   510 *** FOL and ZF ***
   511 
   512 * FOL: there is a new splitter `split_asm_tac' that can be used e.g. 
   513   with `addloop' of the simplifier to faciliate case splitting in premises.
   514 
   515 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
   516 in HOL, they strip ALL and --> from proved theorems;
   517 
   518 
   519 
   520 New in Isabelle94-8 (May 1997)
   521 ------------------------------
   522 
   523 *** General Changes ***
   524 
   525 * new utilities to build / run / maintain Isabelle etc. (in parts
   526 still somewhat experimental); old Makefiles etc. still functional;
   527 
   528 * new 'Isabelle System Manual';
   529 
   530 * INSTALL text, together with ./configure and ./build scripts;
   531 
   532 * reimplemented type inference for greater efficiency, better error
   533 messages and clean internal interface;
   534 
   535 * prlim command for dealing with lots of subgoals (an easier way of
   536 setting goals_limit);
   537 
   538 
   539 *** Syntax ***
   540 
   541 * supports alternative (named) syntax tables (parser and pretty
   542 printer); internal interface is provided by add_modesyntax(_i);
   543 
   544 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
   545 be used in conjunction with the Isabelle symbol font; uses the
   546 "symbols" syntax table;
   547 
   548 * added token_translation interface (may translate name tokens in
   549 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
   550 the current print_mode); IMPORTANT: user print translation functions
   551 are responsible for marking newly introduced bounds
   552 (Syntax.mark_boundT);
   553 
   554 * token translations for modes "xterm" and "xterm_color" that display
   555 names in bold, underline etc. or colors (which requires a color
   556 version of xterm);
   557 
   558 * infixes may now be declared with names independent of their syntax;
   559 
   560 * added typed_print_translation (like print_translation, but may
   561 access type of constant);
   562 
   563 
   564 *** Classical Reasoner ***
   565 
   566 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
   567 some limitations.  Blast_tac...
   568   + ignores addss, addbefore, addafter; this restriction is intrinsic
   569   + ignores elimination rules that don't have the correct format
   570 	(the conclusion MUST be a formula variable)
   571   + ignores types, which can make HOL proofs fail
   572   + rules must not require higher-order unification, e.g. apply_type in ZF
   573     [message "Function Var's argument not a bound variable" relates to this]
   574   + its proof strategy is more general but can actually be slower
   575 
   576 * substitution with equality assumptions no longer permutes other
   577 assumptions;
   578 
   579 * minor changes in semantics of addafter (now called addaltern); renamed
   580 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
   581 (and access functions for it);
   582 
   583 * improved combination of classical reasoner and simplifier: 
   584   + functions for handling clasimpsets
   585   + improvement of addss: now the simplifier is called _after_ the
   586     safe steps.
   587   + safe variant of addss called addSss: uses safe simplifications
   588     _during_ the safe steps. It is more complete as it allows multiple 
   589     instantiations of unknowns (e.g. with slow_tac).
   590 
   591 *** Simplifier ***
   592 
   593 * added interface for simplification procedures (functions that
   594 produce *proven* rewrite rules on the fly, depending on current
   595 redex);
   596 
   597 * ordering on terms as parameter (used for ordered rewriting);
   598 
   599 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
   600 
   601 * the solver is now split into a safe and an unsafe part.
   602 This should be invisible for the normal user, except that the
   603 functions setsolver and addsolver have been renamed to setSolver and
   604 addSolver; added safe_asm_full_simp_tac;
   605 
   606 
   607 *** HOL ***
   608 
   609 * a generic induction tactic `induct_tac' which works for all datatypes and
   610 also for type `nat';
   611 
   612 * a generic case distinction tactic `exhaust_tac' which works for all
   613 datatypes and also for type `nat';
   614 
   615 * each datatype comes with a function `size';
   616 
   617 * patterns in case expressions allow tuple patterns as arguments to
   618 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
   619 
   620 * primrec now also works with type nat;
   621 
   622 * recdef: a new declaration form, allows general recursive functions to be
   623 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
   624 
   625 * the constant for negation has been renamed from "not" to "Not" to
   626 harmonize with FOL, ZF, LK, etc.;
   627 
   628 * HOL/ex/LFilter theory of a corecursive "filter" functional for
   629 infinite lists;
   630 
   631 * HOL/Modelcheck demonstrates invocation of model checker oracle;
   632 
   633 * HOL/ex/Ring.thy declares cring_simp, which solves equational
   634 problems in commutative rings, using axiomatic type classes for + and *;
   635 
   636 * more examples in HOL/MiniML and HOL/Auth;
   637 
   638 * more default rewrite rules for quantifiers, union/intersection;
   639 
   640 * a new constant `arbitrary == @x.False';
   641 
   642 * HOLCF/IOA replaces old HOL/IOA;
   643 
   644 * HOLCF changes: derived all rules and arities 
   645   + axiomatic type classes instead of classes 
   646   + typedef instead of faking type definitions
   647   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
   648   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
   649   + eliminated the types void, one, tr
   650   + use unit lift and bool lift (with translations) instead of one and tr
   651   + eliminated blift from Lift3.thy (use Def instead of blift)
   652   all eliminated rules are derived as theorems --> no visible changes ;
   653 
   654 
   655 *** ZF ***
   656 
   657 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
   658 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
   659 as ZF_cs addSIs [equalityI];
   660 
   661 
   662 
   663 New in Isabelle94-7 (November 96)
   664 ---------------------------------
   665 
   666 * allowing negative levels (as offsets) in prlev and choplev;
   667 
   668 * super-linear speedup for large simplifications;
   669 
   670 * FOL, ZF and HOL now use miniscoping: rewriting pushes
   671 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
   672 FAIL); can suppress it using the command Delsimps (ex_simps @
   673 all_simps); De Morgan laws are also now included, by default;
   674 
   675 * improved printing of ==>  :  ~:
   676 
   677 * new object-logic "Sequents" adds linear logic, while replacing LK
   678 and Modal (thanks to Sara Kalvala);
   679 
   680 * HOL/Auth: correctness proofs for authentication protocols;
   681 
   682 * HOL: new auto_tac combines rewriting and classical reasoning (many
   683 examples on HOL/Auth);
   684 
   685 * HOL: new command AddIffs for declaring theorems of the form P=Q to
   686 the rewriter and classical reasoner simultaneously;
   687 
   688 * function uresult no longer returns theorems in "standard" format;
   689 regain previous version by: val uresult = standard o uresult;
   690 
   691 
   692 
   693 New in Isabelle94-6
   694 -------------------
   695 
   696 * oracles -- these establish an interface between Isabelle and trusted
   697 external reasoners, which may deliver results as theorems;
   698 
   699 * proof objects (in particular record all uses of oracles);
   700 
   701 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
   702 
   703 * "constdefs" section in theory files;
   704 
   705 * "primrec" section (HOL) no longer requires names;
   706 
   707 * internal type "tactic" now simply "thm -> thm Sequence.seq";
   708 
   709 
   710 
   711 New in Isabelle94-5
   712 -------------------
   713 
   714 * reduced space requirements;
   715 
   716 * automatic HTML generation from theories;
   717 
   718 * theory files no longer require "..." (quotes) around most types;
   719 
   720 * new examples, including two proofs of the Church-Rosser theorem;
   721 
   722 * non-curried (1994) version of HOL is no longer distributed;
   723 
   724 
   725 
   726 New in Isabelle94-4
   727 -------------------
   728 
   729 * greatly reduced space requirements;
   730 
   731 * theory files (.thy) no longer require \...\ escapes at line breaks;
   732 
   733 * searchable theorem database (see the section "Retrieving theorems" on 
   734 page 8 of the Reference Manual);
   735 
   736 * new examples, including Grabczewski's monumental case study of the
   737 Axiom of Choice;
   738 
   739 * The previous version of HOL renamed to Old_HOL;
   740 
   741 * The new version of HOL (previously called CHOL) uses a curried syntax 
   742 for functions.  Application looks like f a b instead of f(a,b);
   743 
   744 * Mutually recursive inductive definitions finally work in HOL;
   745 
   746 * In ZF, pattern-matching on tuples is now available in all abstractions and
   747 translates to the operator "split";
   748 
   749 
   750 
   751 New in Isabelle94-3
   752 -------------------
   753 
   754 * new infix operator, addss, allowing the classical reasoner to 
   755 perform simplification at each step of its search.  Example:
   756 	fast_tac (cs addss ss)
   757 
   758 * a new logic, CHOL, the same as HOL, but with a curried syntax 
   759 for functions.  Application looks like f a b instead of f(a,b).  Also pairs 
   760 look like (a,b) instead of <a,b>;
   761 
   762 * PLEASE NOTE: CHOL will eventually replace HOL!
   763 
   764 * In CHOL, pattern-matching on tuples is now available in all abstractions.
   765 It translates to the operator "split".  A new theory of integers is available;
   766 
   767 * In ZF, integer numerals now denote two's-complement binary integers.
   768 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
   769 
   770 * Many new examples: I/O automata, Church-Rosser theorem, equivalents 
   771 of the Axiom of Choice;
   772 
   773 
   774 
   775 New in Isabelle94-2
   776 -------------------
   777 
   778 * Significantly faster resolution;  
   779 
   780 * the different sections in a .thy file can now be mixed and repeated
   781 freely;
   782 
   783 * Database of theorems for FOL, HOL and ZF.  New
   784 commands including qed, qed_goal and bind_thm store theorems in the database.
   785 
   786 * Simple database queries: return a named theorem (get_thm) or all theorems of
   787 a given theory (thms_of), or find out what theory a theorem was proved in
   788 (theory_of_thm);
   789 
   790 * Bugs fixed in the inductive definition and datatype packages;
   791 
   792 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
   793 and HOL_dup_cs obsolete;
   794 
   795 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
   796 have been removed;
   797 
   798 * Simpler definition of function space in ZF;
   799 
   800 * new results about cardinal and ordinal arithmetic in ZF;
   801 
   802 * 'subtype' facility in HOL for introducing new types as subsets of existing
   803 types;
   804 
   805 
   806 $Id$