NEWS
author nipkow
Wed Jan 27 17:11:39 1999 +0100 (1999-01-27)
changeset 6157 29942d3a1818
parent 6155 e387d188d0ca
child 6174 9fb306ded7e5
permissions -rw-r--r--
arith_tac for min/max
     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 * HOL: Removed the obsolete syntax "Compl A"; use -A for set complement
    10 
    11 * ZF: The con_defs part of an inductive definition may no longer refer to 
    12   constants declared in the same theory;
    13 
    14 * HOL, ZF: the function mk_cases, generated by the inductive definition 
    15   package, has lost an argument.  To simplify its result, it uses the default
    16   simpset instead of a supplied list of theorems.
    17 
    18 
    19 *** Proof tools ***
    20 
    21 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a decision
    22 procedure for linear arithmetic. Currently it is used for types `nat' and
    23 `int' in HOL (see below) but can, should and will be instantiated for other
    24 types and logics as well.
    25 
    26 
    27 *** General ***
    28 
    29 * in locales, the "assumes" and "defines" parts may be omitted if empty;
    30 
    31 * new print_mode "xsymbols" for extended symbol support 
    32   (e.g. genuiely long arrows)
    33 
    34 *** HOL ***
    35 
    36 * There are now decision procedures for linear arithmetic over nat and int:
    37 
    38 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=', `+',
    39 `-', `Suc', `min', `max' and numerical constants; other subterms are treated
    40 as atomic; subformulae not involving type `nat' or `int' are ignored;
    41 quantified subformulae are ignored unless they are positive universal or
    42 negative existential. The tactic has to be invoked by hand and can be a
    43 little bit slow. In particular, the running time is exponential in the number
    44 of occurrences of `min' and `max', and `-' on `nat'.
    45 
    46 2. fast_arith_tac is a cut-down version of arith_tac: it only takes (negated)
    47 (in)equalities among the premises and the conclusion into account (i.e. no
    48 compound formulae) and does not know about `min' and `max', and `-' on
    49 `nat'. It is fast and is used automatically by the simplifier.
    50 
    51 NB: At the moment, these decision procedures do not cope with mixed nat/int
    52 formulae where the two parts interact, such as `m < n ==> int(m) < int(n)'.
    53 
    54 *** Internal programming interfaces ***
    55 
    56 * tuned current_goals_markers semantics: begin / end goal avoids
    57 printing empty lines;
    58 
    59 * removed prs and prs_fn hook, which was broken because it did not
    60 include \n in its semantics, forcing writeln to add one
    61 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
    62 string -> unit if you really want to output text without newline;
    63 
    64 
    65 *** ZF ***
    66 
    67 * new primrec section allows primitive recursive functions to be given
    68   directly (as in HOL) over datatypes and the natural numbers;
    69 
    70 * new tactics induct_tac and exhaust_tac for induction (or case analysis)
    71   over datatypes and the natural numbers;
    72 
    73 * the datatype declaration of type T now defines the recursor T_rec;
    74 
    75 * simplification automatically does freeness reasoning for datatype
    76   constructors;
    77 
    78 * automatic type-inference, with AddTCs command to insert new type-checking
    79   rules;
    80 
    81 * datatype introduction rules are now added as Safe Introduction rules to
    82   the claset;
    83 
    84 * The syntax "if P then x else y" is now available in addition to if(P,x,y).
    85 
    86 
    87 New in Isabelle98-1 (October 1998)
    88 ----------------------------------
    89 
    90 *** Overview of INCOMPATIBILITIES (see below for more details) ***
    91 
    92 * several changes of automated proof tools;
    93 
    94 * HOL: major changes to the inductive and datatype packages, including
    95 some minor incompatibilities of theory syntax;
    96 
    97 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
    98 called `inj_on';
    99 
   100 * HOL: removed duplicate thms in Arith:
   101   less_imp_add_less  should be replaced by  trans_less_add1
   102   le_imp_add_le      should be replaced by  trans_le_add1
   103 
   104 * HOL: unary minus is now overloaded (new type constraints may be
   105 required);
   106 
   107 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
   108 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
   109 now taken as an integer constant.
   110 
   111 * Pure: ML function 'theory_of' renamed to 'theory';
   112 
   113 
   114 *** Proof tools ***
   115 
   116 * Simplifier:
   117   1. Asm_full_simp_tac is now more aggressive.
   118      1. It will sometimes reorient premises if that increases their power to
   119         simplify.
   120      2. It does no longer proceed strictly from left to right but may also
   121         rotate premises to achieve further simplification.
   122      For compatibility reasons there is now Asm_lr_simp_tac which is like the
   123      old Asm_full_simp_tac in that it does not rotate premises.
   124   2. The simplifier now knows a little bit about nat-arithmetic.
   125 
   126 * Classical reasoner: wrapper mechanism for the classical reasoner now
   127 allows for selected deletion of wrappers, by introduction of names for
   128 wrapper functionals.  This implies that addbefore, addSbefore,
   129 addaltern, and addSaltern now take a pair (name, tactic) as argument,
   130 and that adding two tactics with the same name overwrites the first
   131 one (emitting a warning).
   132   type wrapper = (int -> tactic) -> (int -> tactic)
   133   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
   134   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
   135   delWrapper, delSWrapper: claset *  string            -> claset
   136   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
   137 
   138 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
   139 semantics; addbefore now affects only the unsafe part of step_tac
   140 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
   141 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
   142 by Force_tac;
   143 
   144 * Classical reasoner: setwrapper to setWrapper and compwrapper to
   145 compWrapper; added safe wrapper (and access functions for it);
   146 
   147 * HOL/split_all_tac is now much faster and fails if there is nothing
   148 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
   149 and the names of the automatically generated variables have changed.
   150 split_all_tac has moved within claset() from unsafe wrappers to safe
   151 wrappers, which means that !!-bound variables are split much more
   152 aggressively, and safe_tac and clarify_tac now split such variables.
   153 If this splitting is not appropriate, use delSWrapper "split_all_tac".
   154 Note: the same holds for record_split_tac, which does the job of
   155 split_all_tac for record fields.
   156 
   157 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
   158 permanently to the default simpset using Addsplits just like
   159 Addsimps. They can be removed via Delsplits just like
   160 Delsimps. Lower-case versions are also available.
   161 
   162 * HOL/Simplifier: The rule split_if is now part of the default
   163 simpset. This means that the simplifier will eliminate all occurrences
   164 of if-then-else in the conclusion of a goal. To prevent this, you can
   165 either remove split_if completely from the default simpset by
   166 `Delsplits [split_if]' or remove it in a specific call of the
   167 simplifier using `... delsplits [split_if]'.  You can also add/delete
   168 other case splitting rules to/from the default simpset: every datatype
   169 generates suitable rules `split_t_case' and `split_t_case_asm' (where
   170 t is the name of the datatype).
   171 
   172 * Classical reasoner / Simplifier combination: new force_tac (and
   173 derivatives Force_tac, force) combines rewriting and classical
   174 reasoning (and whatever other tools) similarly to auto_tac, but is
   175 aimed to solve the given subgoal completely.
   176 
   177 
   178 *** General ***
   179 
   180 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
   181 and `goalw': the theory is no longer needed as an explicit argument -
   182 the current theory context is used; assumptions are no longer returned
   183 at the ML-level unless one of them starts with ==> or !!; it is
   184 recommended to convert to these new commands using isatool fixgoal
   185 (backup your sources first!);
   186 
   187 * new top-level commands 'thm' and 'thms' for retrieving theorems from
   188 the current theory context, and 'theory' to lookup stored theories;
   189 
   190 * new theory section 'locale' for declaring constants, assumptions and
   191 definitions that have local scope;
   192 
   193 * new theory section 'nonterminals' for purely syntactic types;
   194 
   195 * new theory section 'setup' for generic ML setup functions
   196 (e.g. package initialization);
   197 
   198 * the distribution now includes Isabelle icons: see
   199 lib/logo/isabelle-{small,tiny}.xpm;
   200 
   201 * isatool install - install binaries with absolute references to
   202 ISABELLE_HOME/bin;
   203 
   204 * isatool logo -- create instances of the Isabelle logo (as EPS);
   205 
   206 * print mode 'emacs' reserved for Isamode;
   207 
   208 * support multiple print (ast) translations per constant name;
   209 
   210 
   211 *** HOL ***
   212 
   213 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
   214 
   215 * HOL/inductive package reorganized and improved: now supports mutual
   216 definitions such as
   217 
   218   inductive EVEN ODD
   219     intrs
   220       null "0 : EVEN"
   221       oddI "n : EVEN ==> Suc n : ODD"
   222       evenI "n : ODD ==> Suc n : EVEN"
   223 
   224 new theorem list "elims" contains an elimination rule for each of the
   225 recursive sets; inductive definitions now handle disjunctive premises
   226 correctly (also ZF);
   227 
   228 INCOMPATIBILITIES: requires Inductive as an ancestor; component
   229 "mutual_induct" no longer exists - the induction rule is always
   230 contained in "induct";
   231 
   232 
   233 * HOL/datatype package re-implemented and greatly improved: now
   234 supports mutually recursive datatypes such as
   235 
   236   datatype
   237     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
   238             | SUM ('a aexp) ('a aexp)
   239             | DIFF ('a aexp) ('a aexp)
   240             | NUM 'a
   241   and
   242     'a bexp = LESS ('a aexp) ('a aexp)
   243             | AND ('a bexp) ('a bexp)
   244             | OR ('a bexp) ('a bexp)
   245 
   246 as well as indirectly recursive datatypes such as
   247 
   248   datatype
   249     ('a, 'b) term = Var 'a
   250                   | App 'b ((('a, 'b) term) list)
   251 
   252 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
   253 induction on mutually / indirectly recursive datatypes.
   254 
   255 Primrec equations are now stored in theory and can be accessed via
   256 <function_name>.simps.
   257 
   258 INCOMPATIBILITIES:
   259 
   260   - Theories using datatypes must now have theory Datatype as an
   261     ancestor.
   262   - The specific <typename>.induct_tac no longer exists - use the
   263     generic induct_tac instead.
   264   - natE has been renamed to nat.exhaust - use exhaust_tac
   265     instead of res_inst_tac ... natE. Note that the variable
   266     names in nat.exhaust differ from the names in natE, this
   267     may cause some "fragile" proofs to fail.
   268   - The theorems split_<typename>_case and split_<typename>_case_asm
   269     have been renamed to <typename>.split and <typename>.split_asm.
   270   - Since default sorts of type variables are now handled correctly,
   271     some datatype definitions may have to be annotated with explicit
   272     sort constraints.
   273   - Primrec definitions no longer require function name and type
   274     of recursive argument.
   275 
   276 Consider using isatool fixdatatype to adapt your theories and proof
   277 scripts to the new package (backup your sources first!).
   278 
   279 
   280 * HOL/record package: considerably improved implementation; now
   281 includes concrete syntax for record types, terms, updates; theorems
   282 for surjective pairing and splitting !!-bound record variables; proof
   283 support is as follows:
   284 
   285   1) standard conversions (selectors or updates applied to record
   286 constructor terms) are part of the standard simpset;
   287 
   288   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
   289 made part of standard simpset and claset via addIffs;
   290 
   291   3) a tactic for record field splitting (record_split_tac) is part of
   292 the standard claset (addSWrapper);
   293 
   294 To get a better idea about these rules you may retrieve them via
   295 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
   296 the name of your record type.
   297 
   298 The split tactic 3) conceptually simplifies by the following rule:
   299 
   300   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
   301 
   302 Thus any record variable that is bound by meta-all will automatically
   303 blow up into some record constructor term, consequently the
   304 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
   305 solve record problems automatically.
   306 
   307 
   308 * reorganized the main HOL image: HOL/Integ and String loaded by
   309 default; theory Main includes everything;
   310 
   311 * automatic simplification of integer sums and comparisons, using cancellation;
   312 
   313 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
   314 
   315 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
   316 
   317 * many new identities for unions, intersections, set difference, etc.;
   318 
   319 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
   320 called split_if, split_split, split_sum_case and split_nat_case (to go
   321 with add/delsplits);
   322 
   323 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
   324 (?x::unit) = (); this is made part of the default simpset, which COULD
   325 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
   326 'Delsimprocs [unit_eq_proc];' as last resort); also note that
   327 unit_abs_eta_conv is added in order to counter the effect of
   328 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
   329 %u.f();
   330 
   331 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
   332 makes more sense);
   333 
   334 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   335   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   336   disjointness reasoning but breaking a few old proofs.
   337 
   338 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
   339 to 'converse' from 'inverse' (for compatibility with ZF and some
   340 literature);
   341 
   342 * HOL/recdef can now declare non-recursive functions, with {} supplied as
   343 the well-founded relation;
   344 
   345 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
   346     Compl A.  The "Compl" syntax remains available as input syntax for this
   347     release ONLY.
   348 
   349 * HOL/Update: new theory of function updates:
   350     f(a:=b) == %x. if x=a then b else f x
   351 may also be iterated as in f(a:=b,c:=d,...);
   352 
   353 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
   354 
   355 * HOL/List:
   356   - new function list_update written xs[i:=v] that updates the i-th
   357     list position. May also be iterated as in xs[i:=a,j:=b,...].
   358   - new function `upt' written [i..j(] which generates the list
   359     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
   360     bound write [i..j], which is a shorthand for [i..j+1(].
   361   - new lexicographic orderings and corresponding wellfoundedness theorems.
   362 
   363 * HOL/Arith:
   364   - removed 'pred' (predecessor) function;
   365   - generalized some theorems about n-1;
   366   - many new laws about "div" and "mod";
   367   - new laws about greatest common divisors (see theory ex/Primes);
   368 
   369 * HOL/Relation: renamed the relational operator r^-1 "converse"
   370 instead of "inverse";
   371 
   372 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
   373   of the multiset ordering;
   374 
   375 * directory HOL/Real: a construction of the reals using Dedekind cuts
   376   (not included by default);
   377 
   378 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
   379 
   380 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
   381   programs, i.e. different program variables may have different types.
   382 
   383 * calling (stac rew i) now fails if "rew" has no effect on the goal
   384   [previously, this check worked only if the rewrite rule was unconditional]
   385   Now rew can involve either definitions or equalities (either == or =).
   386 
   387 
   388 *** ZF ***
   389 
   390 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
   391   only the theorems proved on ZF.ML;
   392 
   393 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
   394   It and 'sym RS equals0D' are now in the default  claset, giving automatic
   395   disjointness reasoning but breaking a few old proofs.
   396 
   397 * ZF/Update: new theory of function updates
   398     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
   399   may also be iterated as in f(a:=b,c:=d,...);
   400 
   401 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
   402 
   403 * calling (stac rew i) now fails if "rew" has no effect on the goal
   404   [previously, this check worked only if the rewrite rule was unconditional]
   405   Now rew can involve either definitions or equalities (either == or =).
   406 
   407 * case_tac provided for compatibility with HOL
   408     (like the old excluded_middle_tac, but with subgoals swapped)
   409 
   410 
   411 *** Internal programming interfaces ***
   412 
   413 * Pure: several new basic modules made available for general use, see
   414 also src/Pure/README;
   415 
   416 * improved the theory data mechanism to support encapsulation (data
   417 kind name replaced by private Object.kind, acting as authorization
   418 key); new type-safe user interface via functor TheoryDataFun; generic
   419 print_data function becomes basically useless;
   420 
   421 * removed global_names compatibility flag -- all theory declarations
   422 are qualified by default;
   423 
   424 * module Pure/Syntax now offers quote / antiquote translation
   425 functions (useful for Hoare logic etc. with implicit dependencies);
   426 see HOL/ex/Antiquote for an example use;
   427 
   428 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
   429 cterm -> thm;
   430 
   431 * new tactical CHANGED_GOAL for checking that a tactic modifies a
   432 subgoal;
   433 
   434 * Display.print_goals function moved to Locale.print_goals;
   435 
   436 * standard print function for goals supports current_goals_markers
   437 variable for marking begin of proof, end of proof, start of goal; the
   438 default is ("", "", ""); setting current_goals_markers := ("<proof>",
   439 "</proof>", "<goal>") causes SGML like tagged proof state printing,
   440 for example;
   441 
   442 
   443 
   444 New in Isabelle98 (January 1998)
   445 --------------------------------
   446 
   447 *** Overview of INCOMPATIBILITIES (see below for more details) ***
   448 
   449 * changed lexical syntax of terms / types: dots made part of long
   450 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
   451 
   452 * simpset (and claset) reference variable replaced by functions
   453 simpset / simpset_ref;
   454 
   455 * no longer supports theory aliases (via merge) and non-trivial
   456 implicit merge of thms' signatures;
   457 
   458 * most internal names of constants changed due to qualified names;
   459 
   460 * changed Pure/Sequence interface (see Pure/seq.ML);
   461 
   462 
   463 *** General Changes ***
   464 
   465 * hierachically structured name spaces (for consts, types, axms, thms
   466 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
   467 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
   468 isatool fixdots ensures space after dots (e.g. "%x. x"); set
   469 long_names for fully qualified output names; NOTE: ML programs
   470 (special tactics, packages etc.) referring to internal names may have
   471 to be adapted to cope with fully qualified names; in case of severe
   472 backward campatibility problems try setting 'global_names' at compile
   473 time to have enrything declared within a flat name space; one may also
   474 fine tune name declarations in theories via the 'global' and 'local'
   475 section;
   476 
   477 * reimplemented the implicit simpset and claset using the new anytype
   478 data filed in signatures; references simpset:simpset ref etc. are
   479 replaced by functions simpset:unit->simpset and
   480 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
   481 to patch your ML files accordingly;
   482 
   483 * HTML output now includes theory graph data for display with Java
   484 applet or isatool browser; data generated automatically via isatool
   485 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
   486 
   487 * defs may now be conditional; improved rewrite_goals_tac to handle
   488 conditional equations;
   489 
   490 * defs now admits additional type arguments, using TYPE('a) syntax;
   491 
   492 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
   493 creates a new theory node; implicit merge of thms' signatures is
   494 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
   495 transfer:theory->thm->thm in (rare) cases;
   496 
   497 * improved handling of draft signatures / theories; draft thms (and
   498 ctyps, cterms) are automatically promoted to real ones;
   499 
   500 * slightly changed interfaces for oracles: admit many per theory, named
   501 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
   502 
   503 * print_goals: optional output of const types (set show_consts and
   504 show_types);
   505 
   506 * improved output of warnings (###) and errors (***);
   507 
   508 * subgoal_tac displays a warning if the new subgoal has type variables;
   509 
   510 * removed old README and Makefiles;
   511 
   512 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
   513 
   514 * removed obsolete init_pps and init_database;
   515 
   516 * deleted the obsolete tactical STATE, which was declared by
   517     fun STATE tacfun st = tacfun st st;
   518 
   519 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
   520 (which abbreviates $HOME);
   521 
   522 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
   523 use isatool fixseq to adapt your ML programs (this works for fully
   524 qualified references to the Sequence structure only!);
   525 
   526 * use_thy no longer requires writable current directory; it always
   527 reloads .ML *and* .thy file, if either one is out of date;
   528 
   529 
   530 *** Classical Reasoner ***
   531 
   532 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
   533 tactics that use classical reasoning to simplify a subgoal without
   534 splitting it into several subgoals;
   535 
   536 * Safe_tac: like safe_tac but uses the default claset;
   537 
   538 
   539 *** Simplifier ***
   540 
   541 * added simplification meta rules:
   542     (asm_)(full_)simplify: simpset -> thm -> thm;
   543 
   544 * simplifier.ML no longer part of Pure -- has to be loaded by object
   545 logics (again);
   546 
   547 * added prems argument to simplification procedures;
   548 
   549 * HOL, FOL, ZF: added infix function `addsplits':
   550   instead of `<simpset> setloop (split_tac <thms>)'
   551   you can simply write `<simpset> addsplits <thms>'
   552 
   553 
   554 *** Syntax ***
   555 
   556 * TYPE('a) syntax for type reflection terms;
   557 
   558 * no longer handles consts with name "" -- declare as 'syntax' instead;
   559 
   560 * pretty printer: changed order of mixfix annotation preference (again!);
   561 
   562 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
   563 
   564 
   565 *** HOL ***
   566 
   567 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
   568   with `addloop' of the simplifier to faciliate case splitting in premises.
   569 
   570 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
   571 
   572 * HOL/Auth: new protocol proofs including some for the Internet
   573   protocol TLS;
   574 
   575 * HOL/Map: new theory of `maps' a la VDM;
   576 
   577 * HOL/simplifier: simplification procedures nat_cancel_sums for
   578 cancelling out common nat summands from =, <, <= (in)equalities, or
   579 differences; simplification procedures nat_cancel_factor for
   580 cancelling common factor from =, <, <= (in)equalities over natural
   581 sums; nat_cancel contains both kinds of procedures, it is installed by
   582 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
   583 
   584 * HOL/simplifier: terms of the form
   585   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
   586   are rewritten to
   587   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
   588   and those of the form
   589   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
   590   are rewritten to
   591   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
   592 
   593 * HOL/datatype
   594   Each datatype `t' now comes with a theorem `split_t_case' of the form
   595 
   596   P(t_case f1 ... fn x) =
   597      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
   598         ...
   599        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
   600      )
   601 
   602   and a theorem `split_t_case_asm' of the form
   603 
   604   P(t_case f1 ... fn x) =
   605     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
   606         ...
   607        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
   608      )
   609   which can be added to a simpset via `addsplits'. The existing theorems
   610   expand_list_case and expand_option_case have been renamed to
   611   split_list_case and split_option_case.
   612 
   613 * HOL/Arithmetic:
   614   - `pred n' is automatically converted to `n-1'.
   615     Users are strongly encouraged not to use `pred' any longer,
   616     because it will disappear altogether at some point.
   617   - Users are strongly encouraged to write "0 < n" rather than
   618     "n ~= 0". Theorems and proof tools have been modified towards this
   619     `standard'.
   620 
   621 * HOL/Lists:
   622   the function "set_of_list" has been renamed "set" (and its theorems too);
   623   the function "nth" now takes its arguments in the reverse order and
   624   has acquired the infix notation "!" as in "xs!n".
   625 
   626 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
   627 
   628 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
   629   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
   630 
   631 * HOL/record: extensible records with schematic structural subtyping
   632 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
   633 still lacks various theorems and concrete record syntax;
   634 
   635 
   636 *** HOLCF ***
   637 
   638 * removed "axioms" and "generated by" sections;
   639 
   640 * replaced "ops" section by extended "consts" section, which is capable of
   641   handling the continuous function space "->" directly;
   642 
   643 * domain package:
   644   . proves theorems immediately and stores them in the theory,
   645   . creates hierachical name space,
   646   . now uses normal mixfix annotations (instead of cinfix...),
   647   . minor changes to some names and values (for consistency),
   648   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
   649   . separator between mutual domain defs: changed "," to "and",
   650   . improved handling of sort constraints;  now they have to
   651     appear on the left-hand side of the equations only;
   652 
   653 * fixed LAM <x,y,zs>.b syntax;
   654 
   655 * added extended adm_tac to simplifier in HOLCF -- can now discharge
   656 adm (%x. P (t x)), where P is chainfinite and t continuous;
   657 
   658 
   659 *** FOL and ZF ***
   660 
   661 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
   662   with `addloop' of the simplifier to faciliate case splitting in premises.
   663 
   664 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
   665 in HOL, they strip ALL and --> from proved theorems;
   666 
   667 
   668 
   669 New in Isabelle94-8 (May 1997)
   670 ------------------------------
   671 
   672 *** General Changes ***
   673 
   674 * new utilities to build / run / maintain Isabelle etc. (in parts
   675 still somewhat experimental); old Makefiles etc. still functional;
   676 
   677 * new 'Isabelle System Manual';
   678 
   679 * INSTALL text, together with ./configure and ./build scripts;
   680 
   681 * reimplemented type inference for greater efficiency, better error
   682 messages and clean internal interface;
   683 
   684 * prlim command for dealing with lots of subgoals (an easier way of
   685 setting goals_limit);
   686 
   687 
   688 *** Syntax ***
   689 
   690 * supports alternative (named) syntax tables (parser and pretty
   691 printer); internal interface is provided by add_modesyntax(_i);
   692 
   693 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
   694 be used in conjunction with the Isabelle symbol font; uses the
   695 "symbols" syntax table;
   696 
   697 * added token_translation interface (may translate name tokens in
   698 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
   699 the current print_mode); IMPORTANT: user print translation functions
   700 are responsible for marking newly introduced bounds
   701 (Syntax.mark_boundT);
   702 
   703 * token translations for modes "xterm" and "xterm_color" that display
   704 names in bold, underline etc. or colors (which requires a color
   705 version of xterm);
   706 
   707 * infixes may now be declared with names independent of their syntax;
   708 
   709 * added typed_print_translation (like print_translation, but may
   710 access type of constant);
   711 
   712 
   713 *** Classical Reasoner ***
   714 
   715 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
   716 some limitations.  Blast_tac...
   717   + ignores addss, addbefore, addafter; this restriction is intrinsic
   718   + ignores elimination rules that don't have the correct format
   719         (the conclusion MUST be a formula variable)
   720   + ignores types, which can make HOL proofs fail
   721   + rules must not require higher-order unification, e.g. apply_type in ZF
   722     [message "Function Var's argument not a bound variable" relates to this]
   723   + its proof strategy is more general but can actually be slower
   724 
   725 * substitution with equality assumptions no longer permutes other
   726 assumptions;
   727 
   728 * minor changes in semantics of addafter (now called addaltern); renamed
   729 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
   730 (and access functions for it);
   731 
   732 * improved combination of classical reasoner and simplifier:
   733   + functions for handling clasimpsets
   734   + improvement of addss: now the simplifier is called _after_ the
   735     safe steps.
   736   + safe variant of addss called addSss: uses safe simplifications
   737     _during_ the safe steps. It is more complete as it allows multiple
   738     instantiations of unknowns (e.g. with slow_tac).
   739 
   740 *** Simplifier ***
   741 
   742 * added interface for simplification procedures (functions that
   743 produce *proven* rewrite rules on the fly, depending on current
   744 redex);
   745 
   746 * ordering on terms as parameter (used for ordered rewriting);
   747 
   748 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
   749 
   750 * the solver is now split into a safe and an unsafe part.
   751 This should be invisible for the normal user, except that the
   752 functions setsolver and addsolver have been renamed to setSolver and
   753 addSolver; added safe_asm_full_simp_tac;
   754 
   755 
   756 *** HOL ***
   757 
   758 * a generic induction tactic `induct_tac' which works for all datatypes and
   759 also for type `nat';
   760 
   761 * a generic case distinction tactic `exhaust_tac' which works for all
   762 datatypes and also for type `nat';
   763 
   764 * each datatype comes with a function `size';
   765 
   766 * patterns in case expressions allow tuple patterns as arguments to
   767 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
   768 
   769 * primrec now also works with type nat;
   770 
   771 * recdef: a new declaration form, allows general recursive functions to be
   772 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
   773 
   774 * the constant for negation has been renamed from "not" to "Not" to
   775 harmonize with FOL, ZF, LK, etc.;
   776 
   777 * HOL/ex/LFilter theory of a corecursive "filter" functional for
   778 infinite lists;
   779 
   780 * HOL/Modelcheck demonstrates invocation of model checker oracle;
   781 
   782 * HOL/ex/Ring.thy declares cring_simp, which solves equational
   783 problems in commutative rings, using axiomatic type classes for + and *;
   784 
   785 * more examples in HOL/MiniML and HOL/Auth;
   786 
   787 * more default rewrite rules for quantifiers, union/intersection;
   788 
   789 * a new constant `arbitrary == @x.False';
   790 
   791 * HOLCF/IOA replaces old HOL/IOA;
   792 
   793 * HOLCF changes: derived all rules and arities
   794   + axiomatic type classes instead of classes
   795   + typedef instead of faking type definitions
   796   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
   797   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
   798   + eliminated the types void, one, tr
   799   + use unit lift and bool lift (with translations) instead of one and tr
   800   + eliminated blift from Lift3.thy (use Def instead of blift)
   801   all eliminated rules are derived as theorems --> no visible changes ;
   802 
   803 
   804 *** ZF ***
   805 
   806 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
   807 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
   808 as ZF_cs addSIs [equalityI];
   809 
   810 
   811 
   812 New in Isabelle94-7 (November 96)
   813 ---------------------------------
   814 
   815 * allowing negative levels (as offsets) in prlev and choplev;
   816 
   817 * super-linear speedup for large simplifications;
   818 
   819 * FOL, ZF and HOL now use miniscoping: rewriting pushes
   820 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
   821 FAIL); can suppress it using the command Delsimps (ex_simps @
   822 all_simps); De Morgan laws are also now included, by default;
   823 
   824 * improved printing of ==>  :  ~:
   825 
   826 * new object-logic "Sequents" adds linear logic, while replacing LK
   827 and Modal (thanks to Sara Kalvala);
   828 
   829 * HOL/Auth: correctness proofs for authentication protocols;
   830 
   831 * HOL: new auto_tac combines rewriting and classical reasoning (many
   832 examples on HOL/Auth);
   833 
   834 * HOL: new command AddIffs for declaring theorems of the form P=Q to
   835 the rewriter and classical reasoner simultaneously;
   836 
   837 * function uresult no longer returns theorems in "standard" format;
   838 regain previous version by: val uresult = standard o uresult;
   839 
   840 
   841 
   842 New in Isabelle94-6
   843 -------------------
   844 
   845 * oracles -- these establish an interface between Isabelle and trusted
   846 external reasoners, which may deliver results as theorems;
   847 
   848 * proof objects (in particular record all uses of oracles);
   849 
   850 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
   851 
   852 * "constdefs" section in theory files;
   853 
   854 * "primrec" section (HOL) no longer requires names;
   855 
   856 * internal type "tactic" now simply "thm -> thm Sequence.seq";
   857 
   858 
   859 
   860 New in Isabelle94-5
   861 -------------------
   862 
   863 * reduced space requirements;
   864 
   865 * automatic HTML generation from theories;
   866 
   867 * theory files no longer require "..." (quotes) around most types;
   868 
   869 * new examples, including two proofs of the Church-Rosser theorem;
   870 
   871 * non-curried (1994) version of HOL is no longer distributed;
   872 
   873 
   874 
   875 New in Isabelle94-4
   876 -------------------
   877 
   878 * greatly reduced space requirements;
   879 
   880 * theory files (.thy) no longer require \...\ escapes at line breaks;
   881 
   882 * searchable theorem database (see the section "Retrieving theorems" on
   883 page 8 of the Reference Manual);
   884 
   885 * new examples, including Grabczewski's monumental case study of the
   886 Axiom of Choice;
   887 
   888 * The previous version of HOL renamed to Old_HOL;
   889 
   890 * The new version of HOL (previously called CHOL) uses a curried syntax
   891 for functions.  Application looks like f a b instead of f(a,b);
   892 
   893 * Mutually recursive inductive definitions finally work in HOL;
   894 
   895 * In ZF, pattern-matching on tuples is now available in all abstractions and
   896 translates to the operator "split";
   897 
   898 
   899 
   900 New in Isabelle94-3
   901 -------------------
   902 
   903 * new infix operator, addss, allowing the classical reasoner to
   904 perform simplification at each step of its search.  Example:
   905         fast_tac (cs addss ss)
   906 
   907 * a new logic, CHOL, the same as HOL, but with a curried syntax
   908 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
   909 look like (a,b) instead of <a,b>;
   910 
   911 * PLEASE NOTE: CHOL will eventually replace HOL!
   912 
   913 * In CHOL, pattern-matching on tuples is now available in all abstractions.
   914 It translates to the operator "split".  A new theory of integers is available;
   915 
   916 * In ZF, integer numerals now denote two's-complement binary integers.
   917 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
   918 
   919 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
   920 of the Axiom of Choice;
   921 
   922 
   923 
   924 New in Isabelle94-2
   925 -------------------
   926 
   927 * Significantly faster resolution;
   928 
   929 * the different sections in a .thy file can now be mixed and repeated
   930 freely;
   931 
   932 * Database of theorems for FOL, HOL and ZF.  New
   933 commands including qed, qed_goal and bind_thm store theorems in the database.
   934 
   935 * Simple database queries: return a named theorem (get_thm) or all theorems of
   936 a given theory (thms_of), or find out what theory a theorem was proved in
   937 (theory_of_thm);
   938 
   939 * Bugs fixed in the inductive definition and datatype packages;
   940 
   941 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
   942 and HOL_dup_cs obsolete;
   943 
   944 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
   945 have been removed;
   946 
   947 * Simpler definition of function space in ZF;
   948 
   949 * new results about cardinal and ordinal arithmetic in ZF;
   950 
   951 * 'subtype' facility in HOL for introducing new types as subsets of existing
   952 types;
   953 
   954 
   955 $Id$