NEWS
author ballarin
Thu Feb 19 15:57:34 2004 +0100 (2004-02-19)
changeset 14398 c5c47703f763
parent 14389 57c2d90936ba
child 14399 dc677b35e54f
permissions -rw-r--r--
Efficient, graph-based reasoner for linear and partial orders.
+ Setup as solver in the HOL simplifier.
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** General ***
     8 
     9 * Provers/order.ML:  new efficient reasoner for partial and linear orders.
    10   Replaces linorder.ML.
    11 
    12 * Pure: Greek letters (except small lambda, \<lambda>), as well as gothic
    13   (\<aa>...\<zz>\<AA>...\<ZZ>), caligraphic (\<A>...\<Z>), and euler
    14   (\<a>...\<z>), are now considered normal letters, and can therefore
    15   be used anywhere where an ASCII letter (a...zA...Z) has until
    16   now. COMPATIBILITY: This obviously changes the parsing of some
    17   terms, especially where a symbol has been used as a binder, say
    18   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed
    19   as an identifier.  Fix it by inserting a space around former
    20   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in
    21   existing theory and ML files.
    22 
    23 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.
    24 
    25 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now 
    26   allowed in identifiers. Similar to greek letters \<^isub> is now considered 
    27   a normal (but invisible) letter. For multiple letter subscripts repeat 
    28   \<^isub> like this: x\<^isub>1\<^isub>2. 
    29 
    30 * Pure: There are now sub-/superscripts that can span more than one
    31   character. Text between \<^bsub> and \<^esub> is set in subscript in
    32   PG and LaTeX, text between \<^bsup> and \<^esup> in superscript. The
    33   new control characters are not identifier parts.
    34 
    35 * Pure: Control-symbols of the form \<^raw...> will literally print the
    36   content of ... to the latex file instead of \isacntrl... . The ... 
    37   accepts all printable characters excluding the end bracket >.
    38 
    39 * Pure: Symbols may only start with one backslash: \<...>. \\<...> is no 
    40   longer accepted by the scanner.
    41 
    42 * Pure: Using new Isar command "finalconsts" (or the ML functions
    43   Theory.add_finals or Theory.add_finals_i) it is now possible to
    44   declare constants "final", which prevents their being given a definition
    45   later.  It is useful for constants whose behaviour is fixed axiomatically
    46   rather than definitionally, such as the meta-logic connectives.
    47 
    48 *** Isar ***
    49 
    50 * Tactic emulation methods ?rule_tac, cut_tac, subgoal_tac and thin_tac:
    51   - Now understand static (Isar) contexts.  As a consequence, users of Isar
    52     locales are no longer forced to write Isar proof scripts.
    53     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
    54     emulations.
    55   - INCOMPATIBILITY: names of variables to be instantiated may no
    56     longer be enclosed in quotes.  Instead, precede variable name with `?'.
    57     This is consistent with the instantiation attribute "where".
    58 
    59 * Attributes "where" and "of":
    60   - Now take type variables of instantiated theorem into account when reading
    61     the instantiation string.  This fixes a bug that caused instantiated
    62     theorems to have too special types in some circumstances.
    63   - "where" permits explicit instantiations of type variables.
    64 
    65 * Calculation commands "moreover" and "also":
    66   Do not reset facts ("this") any more.
    67 
    68 * Locales:
    69   - Goal statements involving the context element "includes" no longer
    70     generate theorems with internal delta predicates (those ending on
    71     "_axioms") in the premise.
    72     Resolve particular premise with <locale>.intro to obtain old form.
    73   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
    74     specification and "includes" elements in goal statement.
    75   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
    76     [intro?] and [elim?] (respectively) by default.
    77 
    78 * HOL: Tactic emulation methods induct_tac and case_tac understand static
    79   (Isar) contexts.
    80 
    81 *** HOL ***
    82 
    83 * Simplifier:
    84   - Much improved handling of linear and partial orders.
    85     Reasoners for linear and partial orders are set up for type classes
    86     "linorder" and "order" respectively, and are added to the default simpset
    87     as solvers.  This means that the simplifier can build transitivity chains
    88     to solve goals from the assumptions.
    89   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications
    90     of blast or auto after simplification become unnecessary because the goal
    91     is solved by simplification already.
    92 
    93 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws, 
    94     all proved in axiomatic type classes for semirings, rings and fields.
    95 
    96 * Numerics:
    97   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are
    98     now formalized using the Ring_and_Field theory mentioned above. 
    99   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently
   100     than before, because now they are set up once in a generic manner.
   101   - INCOMPATIBILITY: many type-specific instances of laws proved in 
   102     Ring_and_Field are no longer available.
   103 
   104 * Type "rat" of the rational numbers is now availabe in HOL-Complex.
   105 
   106 * Records:
   107   - Record types are now by default printed with their type abbreviation
   108     instead of the list of all field types. This can be configured via
   109     the reference "print_record_type_abbr".
   110   - Simproc "record_upd_simproc" for simplification of multiple updates added 
   111     (not enabled by default).
   112   - Tactic "record_split_simp_tac" to split and simplify records added.
   113  
   114 * 'specification' command added, allowing for definition by
   115   specification.  There is also an 'ax_specification' command that
   116   introduces the new constants axiomatically.
   117 
   118 * arith(_tac) is now able to generate counterexamples for reals as well.
   119 
   120 * SET-Protocol: formalization and verification of the SET protocol suite;
   121 
   122 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
   123  defintions, thanks to Sava Krsti\'{c} and John Matthews.
   124 
   125 * Unions and Intersections:
   126   The x-symbol output syntax of UN and INT has been changed
   127   from "\<Union>x \<in> A. B" to "\<Union\<^bsub>x \<in> A\<^esub> B"
   128   i.e. the index formulae has become a subscript, like in normal math.
   129   Similarly for "\<Union>x. B", and for \<Inter> instead of \<Union>.
   130   The subscript version is also accepted as input syntax.
   131 
   132 
   133 New in Isabelle2003 (May 2003)
   134 --------------------------------
   135 
   136 *** General ***
   137 
   138 * Provers/simplifier:
   139 
   140   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   141     Assumptions are now subject to complete mutual simplification,
   142     not just from left to right. The simplifier now preserves
   143     the order of assumptions.
   144 
   145     Potential INCOMPATIBILITY:
   146 
   147     -- simp sometimes diverges where the old version did
   148        not, e.g. invoking simp on the goal
   149 
   150         [| P (f x); y = x; f x = f y |] ==> Q
   151 
   152        now gives rise to the infinite reduction sequence
   153 
   154         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   155 
   156        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   157        kind of problem.
   158 
   159     -- Tactics combining classical reasoner and simplification (such as auto)
   160        are also affected by this change, because many of them rely on
   161        simp. They may sometimes diverge as well or yield a different numbers
   162        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   163        in case of problems. Sometimes subsequent calls to the classical
   164        reasoner will fail because a preceeding call to the simplifier too
   165        eagerly simplified the goal, e.g. deleted redundant premises.
   166 
   167   - The simplifier trace now shows the names of the applied rewrite rules
   168 
   169   - You can limit the number of recursive invocations of the simplifier
   170     during conditional rewriting (where the simplifie tries to solve the
   171     conditions before applying the rewrite rule):
   172     ML "simp_depth_limit := n"
   173     where n is an integer. Thus you can force termination where previously
   174     the simplifier would diverge.
   175 
   176   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   177 
   178   - No longer aborts on failed congruence proof.  Instead, the
   179     congruence is ignored.
   180 
   181 * Pure: New generic framework for extracting programs from constructive
   182   proofs. See HOL/Extraction.thy for an example instantiation, as well
   183   as HOL/Extraction for some case studies.
   184 
   185 * Pure: The main goal of the proof state is no longer shown by default, only
   186 the subgoals. This behaviour is controlled by a new flag.
   187    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   188 (ML: Proof.show_main_goal).
   189 
   190 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   191 rules whose conclusion matches subgoal 1:
   192       PG menu: Isabelle/Isar -> Show me -> matching rules
   193 The rules are ordered by how closely they match the subgoal.
   194 In particular, rules that solve a subgoal outright are displayed first
   195 (or rather last, the way they are printed).
   196 (ML: ProofGeneral.print_intros())
   197 
   198 * Pure: New flag trace_unify_fail causes unification to print
   199 diagnostic information (PG: in trace buffer) when it fails. This is
   200 useful for figuring out why single step proofs like rule, erule or
   201 assumption failed.
   202 
   203 * Pure: Locale specifications now produce predicate definitions
   204 according to the body of text (covering assumptions modulo local
   205 definitions); predicate "loc_axioms" covers newly introduced text,
   206 while "loc" is cumulative wrt. all included locale expressions; the
   207 latter view is presented only on export into the global theory
   208 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   209 on the old view without predicates;
   210 
   211 * Pure: predefined locales "var" and "struct" are useful for sharing
   212 parameters (as in CASL, for example); just specify something like
   213 ``var x + var y + struct M'' as import;
   214 
   215 * Pure: improved thms_containing: proper indexing of facts instead of
   216 raw theorems; check validity of results wrt. current name space;
   217 include local facts of proof configuration (also covers active
   218 locales), cover fixed variables in index; may use "_" in term
   219 specification; an optional limit for the number of printed facts may
   220 be given (the default is 40);
   221 
   222 * Pure: disallow duplicate fact bindings within new-style theory files
   223 (batch-mode only);
   224 
   225 * Provers: improved induct method: assumptions introduced by case
   226 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   227 the goal statement); "foo" still refers to all facts collectively;
   228 
   229 * Provers: the function blast.overloaded has been removed: all constants
   230 are regarded as potentially overloaded, which improves robustness in exchange
   231 for slight decrease in efficiency;
   232 
   233 * Provers/linorder: New generic prover for transitivity reasoning over
   234 linear orders.  Note: this prover is not efficient!
   235 
   236 * Isar: preview of problems to finish 'show' now produce an error
   237 rather than just a warning (in interactive mode);
   238 
   239 
   240 *** HOL ***
   241 
   242 * arith(_tac)
   243 
   244  - Produces a counter example if it cannot prove a goal.
   245    Note that the counter example may be spurious if the goal is not a formula
   246    of quantifier-free linear arithmetic.
   247    In ProofGeneral the counter example appears in the trace buffer.
   248 
   249  - Knows about div k and mod k where k is a numeral of type nat or int.
   250 
   251  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   252    linear arithmetic fails. This takes account of quantifiers and divisibility.
   253    Presburger arithmetic can also be called explicitly via presburger(_tac). 
   254 
   255 * simp's arithmetic capabilities have been enhanced a bit: it now
   256 takes ~= in premises into account (by performing a case split);
   257 
   258 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   259 are distributed over a sum of terms;
   260 
   261 * New tactic "trans_tac" and method "trans" instantiate
   262 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   263 "<=", "<" and "="). 
   264 
   265 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main 
   266 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   267 
   268 * 'typedef' command has new option "open" to suppress the set
   269 definition;
   270 
   271 * functions Min and Max on finite sets have been introduced (theory
   272 Finite_Set);
   273 
   274 * attribute [symmetric] now works for relations as well; it turns
   275 (x,y) : R^-1 into (y,x) : R, and vice versa;
   276 
   277 * induct over a !!-quantified statement (say !!x1..xn):
   278   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   279 
   280 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   281 %x. None. Warning: empty_def now refers to the previously hidden definition
   282 of the empty set.
   283 
   284 * Algebra: formalization of classical algebra.  Intended as base for
   285 any algebraic development in Isabelle.  Currently covers group theory
   286 (up to Sylow's theorem) and ring theory (Universal Property of
   287 Univariate Polynomials).  Contributions welcome;
   288 
   289 * GroupTheory: deleted, since its material has been moved to Algebra;
   290 
   291 * Complex: new directory of the complex numbers with numeric constants, 
   292 nonstandard complex numbers, and some complex analysis, standard and 
   293 nonstandard (Jacques Fleuriot);
   294 
   295 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   296 
   297 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques 
   298 Fleuriot);
   299 
   300 * Real/HahnBanach: updated and adapted to locales;
   301 
   302 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   303 Gray and Kramer);
   304 
   305 * UNITY: added the Meier-Sanders theory of progress sets;
   306 
   307 * MicroJava: bytecode verifier and lightweight bytecode verifier
   308 as abstract algorithms, instantiated to the JVM;
   309 
   310 * Bali: Java source language formalization. Type system, operational
   311 semantics, axiomatic semantics. Supported language features:
   312 classes, interfaces, objects,virtual methods, static methods,
   313 static/instance fields, arrays, access modifiers, definite
   314 assignment, exceptions.
   315 
   316 
   317 *** ZF ***
   318 
   319 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   320 universe, etc.);
   321 
   322 * Main ZF: virtually all theories converted to new-style format;
   323 
   324 
   325 *** ML ***
   326 
   327 * Pure: Tactic.prove provides sane interface for internal proofs;
   328 omits the infamous "standard" operation, so this is more appropriate
   329 than prove_goalw_cterm in many situations (e.g. in simprocs);
   330 
   331 * Pure: improved error reporting of simprocs;
   332 
   333 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   334 up simprocs;
   335 
   336 
   337 *** Document preparation ***
   338 
   339 * uses \par instead of \\ for line breaks in theory text. This may
   340 shift some page breaks in large documents. To get the old behaviour
   341 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   342 
   343 * minimized dependencies of isabelle.sty and isabellesym.sty on 
   344 other packages
   345 
   346 * \<euro> now needs package babel/greek instead of marvosym (which
   347 broke \Rightarrow)
   348 
   349 * normal size for \<zero>...\<nine> (uses \mathbf instead of 
   350 textcomp package)
   351 
   352 
   353 New in Isabelle2002 (March 2002)
   354 --------------------------------
   355 
   356 *** Document preparation ***
   357 
   358 * greatly simplified document preparation setup, including more
   359 graceful interpretation of isatool usedir -i/-d/-D options, and more
   360 instructive isatool mkdir; users should basically be able to get
   361 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   362 users may run a separate document processing stage manually like this:
   363 "isatool usedir -D output HOL Test && isatool document Test/output";
   364 
   365 * theory dependency graph may now be incorporated into documents;
   366 isatool usedir -g true will produce session_graph.eps/.pdf for use
   367 with \includegraphics of LaTeX;
   368 
   369 * proper spacing of consecutive markup elements, especially text
   370 blocks after section headings;
   371 
   372 * support bold style (for single symbols only), input syntax is like
   373 this: "\<^bold>\<alpha>" or "\<^bold>A";
   374 
   375 * \<bullet> is now output as bold \cdot by default, which looks much
   376 better in printed text;
   377 
   378 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   379 note that these symbols are currently unavailable in Proof General /
   380 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   381 
   382 * isatool latex no longer depends on changed TEXINPUTS, instead
   383 isatool document copies the Isabelle style files to the target
   384 location;
   385 
   386 
   387 *** Isar ***
   388 
   389 * Pure/Provers: improved proof by cases and induction;
   390   - 'case' command admits impromptu naming of parameters (such as
   391     "case (Suc n)");
   392   - 'induct' method divinates rule instantiation from the inductive
   393     claim; no longer requires excessive ?P bindings for proper
   394     instantiation of cases;
   395   - 'induct' method properly enumerates all possibilities of set/type
   396     rules; as a consequence facts may be also passed through *type*
   397     rules without further ado;
   398   - 'induct' method now derives symbolic cases from the *rulified*
   399     rule (before it used to rulify cases stemming from the internal
   400     atomized version); this means that the context of a non-atomic
   401     statement becomes is included in the hypothesis, avoiding the
   402     slightly cumbersome show "PROP ?case" form;
   403   - 'induct' may now use elim-style induction rules without chaining
   404     facts, using ``missing'' premises from the goal state; this allows
   405     rules stemming from inductive sets to be applied in unstructured
   406     scripts, while still benefitting from proper handling of non-atomic
   407     statements; NB: major inductive premises need to be put first, all
   408     the rest of the goal is passed through the induction;
   409   - 'induct' proper support for mutual induction involving non-atomic
   410     rule statements (uses the new concept of simultaneous goals, see
   411     below);
   412   - append all possible rule selections, but only use the first
   413     success (no backtracking);
   414   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   415   - undeclared rule case names default to numbers 1, 2, 3, ...;
   416   - added 'print_induct_rules' (covered by help item in recent Proof
   417     General versions);
   418   - moved induct/cases attributes to Pure, methods to Provers;
   419   - generic method setup instantiated for FOL and HOL;
   420 
   421 * Pure: support multiple simultaneous goal statements, for example
   422 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   423 meta-level mechanism, this acts as if several individual goals had
   424 been stated separately; in particular common proof methods need to be
   425 repeated in order to cover all claims; note that a single elimination
   426 step is *not* sufficient to establish the two conjunctions, so this
   427 fails:
   428 
   429   assume "A & B" then have A and B ..   (*".." fails*)
   430 
   431 better use "obtain" in situations as above; alternative refer to
   432 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   433 
   434 * Pure: proper integration with ``locales''; unlike the original
   435 version by Florian Kammüller, Isar locales package high-level proof
   436 contexts rather than raw logical ones (e.g. we admit to include
   437 attributes everywhere); operations on locales include merge and
   438 rename; support for implicit arguments (``structures''); simultaneous
   439 type-inference over imports and text; see also HOL/ex/Locales.thy for
   440 some examples;
   441 
   442 * Pure: the following commands have been ``localized'', supporting a
   443 target locale specification "(in name)": 'lemma', 'theorem',
   444 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   445 stored both within the locale and at the theory level (exported and
   446 qualified by the locale name);
   447 
   448 * Pure: theory goals may now be specified in ``long'' form, with
   449 ad-hoc contexts consisting of arbitrary locale elements. for example
   450 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   451 definitions may be given, too); the result is a meta-level rule with
   452 the context elements being discharged in the obvious way;
   453 
   454 * Pure: new proof command 'using' allows to augment currently used
   455 facts after a goal statement ('using' is syntactically analogous to
   456 'apply', but acts on the goal's facts only); this allows chained facts
   457 to be separated into parts given before and after a claim, as in
   458 ``from a and b have C using d and e <proof>'';
   459 
   460 * Pure: renamed "antecedent" case to "rule_context";
   461 
   462 * Pure: new 'judgment' command records explicit information about the
   463 object-logic embedding (used by several tools internally); no longer
   464 use hard-wired "Trueprop";
   465 
   466 * Pure: added 'corollary' command;
   467 
   468 * Pure: fixed 'token_translation' command;
   469 
   470 * Pure: removed obsolete 'exported' attribute;
   471 
   472 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   473 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   474 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   475 
   476 * Pure: method 'atomize' presents local goal premises as object-level
   477 statements (atomic meta-level propositions); setup controlled via
   478 rewrite rules declarations of 'atomize' attribute; example
   479 application: 'induct' method with proper rule statements in improper
   480 proof *scripts*;
   481 
   482 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   483 now consider the syntactic context of assumptions, giving a better
   484 chance to get type-inference of the arguments right (this is
   485 especially important for locales);
   486 
   487 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   488 mode;
   489 
   490 * Pure/obtain: the formal conclusion "thesis", being marked as
   491 ``internal'', may no longer be reference directly in the text;
   492 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   493 situations;
   494 
   495 * Pure: generic 'sym' attribute which declares a rule both as pure
   496 'elim?' and for the 'symmetric' operation;
   497 
   498 * Pure: marginal comments ``--'' may now occur just anywhere in the
   499 text; the fixed correlation with particular command syntax has been
   500 discontinued;
   501 
   502 * Pure: new method 'rules' is particularly well-suited for proof
   503 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   504 but often produces more compact proof terms with less detours;
   505 
   506 * Pure/Provers/classical: simplified integration with pure rule
   507 attributes and methods; the classical "intro?/elim?/dest?"
   508 declarations coincide with the pure ones; the "rule" method no longer
   509 includes classically swapped intros; "intro" and "elim" methods no
   510 longer pick rules from the context; also got rid of ML declarations
   511 AddXIs/AddXEs/AddXDs; all of this has some potential for
   512 INCOMPATIBILITY;
   513 
   514 * Provers/classical: attribute 'swapped' produces classical inversions
   515 of introduction rules;
   516 
   517 * Provers/simplifier: 'simplified' attribute may refer to explicit
   518 rules instead of full simplifier context; 'iff' attribute handles
   519 conditional rules;
   520 
   521 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   522 
   523 * HOL: 'recdef' now fails on unfinished automated proofs, use
   524 "(permissive)" option to recover old behavior;
   525 
   526 * HOL: 'inductive' no longer features separate (collective) attributes
   527 for 'intros' (was found too confusing);
   528 
   529 * HOL: properly declared induction rules less_induct and
   530 wf_induct_rule;
   531 
   532 
   533 *** HOL ***
   534 
   535 * HOL: moved over to sane numeral syntax; the new policy is as
   536 follows:
   537 
   538   - 0 and 1 are polymorphic constants, which are defined on any
   539   numeric type (nat, int, real etc.);
   540 
   541   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   542   binary representation internally;
   543 
   544   - type nat has special constructor Suc, and generally prefers Suc 0
   545   over 1::nat and Suc (Suc 0) over 2::nat;
   546 
   547 This change may cause significant problems of INCOMPATIBILITY; here
   548 are some hints on converting existing sources:
   549 
   550   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   551   entities, so expressions involving "-" (unary or binary minus) need
   552   to be spaced properly;
   553 
   554   - existing occurrences of "1" may need to be constraint "1::nat" or
   555   even replaced by Suc 0; similar for old "2";
   556 
   557   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   558 
   559   - remove all special provisions on numerals in proofs;
   560 
   561 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   562 representation (depends on bin_arith_simps in the default context);
   563 
   564 * HOL: symbolic syntax for x^2 (numeral 2);
   565 
   566 * HOL: the class of all HOL types is now called "type" rather than
   567 "term"; INCOMPATIBILITY, need to adapt references to this type class
   568 in axclass/classes, instance/arities, and (usually rare) occurrences
   569 in typings (of consts etc.); internally the class is called
   570 "HOL.type", ML programs should refer to HOLogic.typeS;
   571 
   572 * HOL/record package improvements:
   573   - new derived operations "fields" to build a partial record section,
   574     "extend" to promote a fixed record to a record scheme, and
   575     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   576     declared as simp by default;
   577   - shared operations ("more", "fields", etc.) now need to be always
   578     qualified) --- potential INCOMPATIBILITY;
   579   - removed "make_scheme" operations (use "make" with "extend") --
   580     INCOMPATIBILITY;
   581   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   582   - provides cases/induct rules for use with corresponding Isar
   583     methods (for concrete records, record schemes, concrete more
   584     parts, and schematic more parts -- in that order);
   585   - internal definitions directly based on a light-weight abstract
   586     theory of product types over typedef rather than datatype;
   587 
   588 * HOL: generic code generator for generating executable ML code from
   589 specifications; specific support for HOL constructs such as inductive
   590 datatypes and sets, as well as recursive functions; can be invoked
   591 via 'generate_code' theory section;
   592 
   593 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   594 
   595 * HOL: consolidated and renamed several theories.  In particular:
   596 	Ord.thy has been absorbed into HOL.thy
   597 	String.thy has been absorbed into List.thy
   598  
   599 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   600 (beware of argument permutation!);
   601 
   602 * HOL: linorder_less_split superseded by linorder_cases;
   603 
   604 * HOL/List: "nodups" renamed to "distinct";
   605 
   606 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   607 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   608   - Ex_def has changed, now need to use some_eq_ex
   609 
   610 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   611 in this (rare) case use:
   612 
   613   delSWrapper "split_all_tac"
   614   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   615 
   616 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   617 MAY FAIL;
   618 
   619 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   620 Isabelle's type classes, ^ on functions and relations has too general
   621 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   622 necessary to attach explicit type constraints;
   623 
   624 * HOL/Relation: the prefix name of the infix "O" has been changed from
   625 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   626 renamed accordingly (eg "compI" -> "rel_compI").
   627 
   628 * HOL: syntax translations now work properly with numerals and records
   629 expressions;
   630 
   631 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   632 of "lam" -- INCOMPATIBILITY;
   633 
   634 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   635 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   636 renamed "Product_Type.unit";
   637 
   638 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   639 
   640 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   641 the "cases" method);
   642 
   643 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   644 Florian Kammüller);
   645 
   646 * HOL/IMP: updated and converted to new-style theory format; several
   647 parts turned into readable document, with proper Isar proof texts and
   648 some explanations (by Gerwin Klein);
   649 
   650 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   651 
   652 * HOL-Hyperreal is now a logic image;
   653 
   654 
   655 *** HOLCF ***
   656 
   657 * Isar: consts/constdefs supports mixfix syntax for continuous
   658 operations;
   659 
   660 * Isar: domain package adapted to new-style theory format, e.g. see
   661 HOLCF/ex/Dnat.thy;
   662 
   663 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   664 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   665 lift.induct_tac, always use UU instead of Undef;
   666 
   667 * HOLCF/IMP: updated and converted to new-style theory;
   668 
   669 
   670 *** ZF ***
   671 
   672 * Isar: proper integration of logic-specific tools and packages,
   673 including theory commands '(co)inductive', '(co)datatype',
   674 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   675 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   676 
   677 * theory Main no longer includes AC; for the Axiom of Choice, base
   678 your theory on Main_ZFC;
   679 
   680 * the integer library now covers quotients and remainders, with many
   681 laws relating division to addition, multiplication, etc.;
   682 
   683 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   684 typeless version of the formalism;
   685 
   686 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   687 format;
   688 
   689 * ZF/Induct: new directory for examples of inductive definitions,
   690 including theory Multiset for multiset orderings; converted to
   691 new-style theory format;
   692 
   693 * ZF: many new theorems about lists, ordinals, etc.;
   694 
   695 
   696 *** General ***
   697 
   698 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   699 variable proof controls level of detail: 0 = no proofs (only oracle
   700 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   701 also ref manual for further ML interfaces;
   702 
   703 * Pure/axclass: removed obsolete ML interface
   704 goal_subclass/goal_arity;
   705 
   706 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   707 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   708 separate tokens, so expressions involving minus need to be spaced
   709 properly;
   710 
   711 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   712 rather than "infixl" or "infixr";
   713 
   714 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   715 sort constraint specifications in type inference; e.g. "x::_::foo"
   716 ensures that the type of "x" is of sort "foo" (but not necessarily a
   717 type variable);
   718 
   719 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   720 control output of nested => (types); the default behavior is
   721 "type_brackets";
   722 
   723 * Pure/syntax: builtin parse translation for "_constify" turns valued
   724 tokens into AST constants;
   725 
   726 * Pure/syntax: prefer later declarations of translations and print
   727 translation functions; potential INCOMPATIBILITY: need to reverse
   728 multiple declarations for same syntax element constant;
   729 
   730 * Pure/show_hyps reset by default (in accordance to existing Isar
   731 practice);
   732 
   733 * Provers/classical: renamed addaltern to addafter, addSaltern to
   734 addSafter;
   735 
   736 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   737 as well;
   738 
   739 * system: tested support for MacOS X; should be able to get Isabelle +
   740 Proof General to work in a plain Terminal after installing Poly/ML
   741 (e.g. from the Isabelle distribution area) and GNU bash alone
   742 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   743 support requires further installations, e.g. from
   744 http://fink.sourceforge.net/);
   745 
   746 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   747 
   748 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   749 of 40 MB), cf. ML_OPTIONS;
   750 
   751 * system: Proof General keywords specification is now part of the
   752 Isabelle distribution (see etc/isar-keywords.el);
   753 
   754 * system: support for persistent Proof General sessions (refrain from
   755 outdating all loaded theories on startup); user may create writable
   756 logic images like this: ``isabelle -q HOL Test'';
   757 
   758 * system: smart selection of Isabelle process versus Isabelle
   759 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   760 run both "isabelle" and "Isabelle" even if file names are badly
   761 damaged (executable inspects the case of the first letter of its own
   762 name); added separate "isabelle-process" and "isabelle-interface";
   763 
   764 * system: refrain from any attempt at filtering input streams; no
   765 longer support ``8bit'' encoding of old isabelle font, instead proper
   766 iso-latin characters may now be used; the related isatools
   767 "symbolinput" and "nonascii" have disappeared as well;
   768 
   769 * system: removed old "xterm" interface (the print modes "xterm" and
   770 "xterm_color" are still available for direct use in a suitable
   771 terminal);
   772 
   773 
   774 
   775 New in Isabelle99-2 (February 2001)
   776 -----------------------------------
   777 
   778 *** Overview of INCOMPATIBILITIES ***
   779 
   780 * HOL: please note that theories in the Library and elsewhere often use the
   781 new-style (Isar) format; to refer to their theorems in an ML script you must
   782 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   783 
   784 * HOL: inductive package no longer splits induction rule aggressively,
   785 but only as far as specified by the introductions given; the old
   786 format may be recovered via ML function complete_split_rule or attribute
   787 'split_rule (complete)';
   788 
   789 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   790 gfp_Tarski to gfp_unfold;
   791 
   792 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   793 
   794 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   795 relation); infix "^^" has been renamed "``"; infix "``" has been
   796 renamed "`"; "univalent" has been renamed "single_valued";
   797 
   798 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   799 operation;
   800 
   801 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   802 
   803 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   804 
   805 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   806 consequence, it is no longer monotonic wrt. the local goal context
   807 (which is now passed through the inductive cases);
   808 
   809 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   810 \<gg> to \<ggreater>;
   811 
   812 
   813 *** Document preparation ***
   814 
   815 * \isabellestyle{NAME} selects version of Isabelle output (currently
   816 available: are "it" for near math-mode best-style output, "sl" for
   817 slanted text style, and "tt" for plain type-writer; if no
   818 \isabellestyle command is given, output is according to slanted
   819 type-writer);
   820 
   821 * support sub/super scripts (for single symbols only), input syntax is
   822 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   823 
   824 * some more standard symbols; see Appendix A of the system manual for
   825 the complete list of symbols defined in isabellesym.sty;
   826 
   827 * improved isabelle style files; more abstract symbol implementation
   828 (should now use \isamath{...} and \isatext{...} in custom symbol
   829 definitions);
   830 
   831 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   832 state; Note that presentation of goal states does not conform to
   833 actual human-readable proof documents.  Please do not include goal
   834 states into document output unless you really know what you are doing!
   835 
   836 * proper indentation of antiquoted output with proportional LaTeX
   837 fonts;
   838 
   839 * no_document ML operator temporarily disables LaTeX document
   840 generation;
   841 
   842 * isatool unsymbolize tunes sources for plain ASCII communication;
   843 
   844 
   845 *** Isar ***
   846 
   847 * Pure: Isar now suffers initial goal statements to contain unbound
   848 schematic variables (this does not conform to actual readable proof
   849 documents, due to unpredictable outcome and non-compositional proof
   850 checking); users who know what they are doing may use schematic goals
   851 for Prolog-style synthesis of proven results;
   852 
   853 * Pure: assumption method (an implicit finishing) now handles actual
   854 rules as well;
   855 
   856 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   857 initial goal, declare "that" only as Pure intro (only for single
   858 steps); the "that" rule assumption may now be involved in implicit
   859 finishing, thus ".." becomes a feasible for trivial obtains;
   860 
   861 * Pure: default proof step now includes 'intro_classes'; thus trivial
   862 instance proofs may be performed by "..";
   863 
   864 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   865 statements as well;
   866 
   867 * Pure: more robust selection of calculational rules;
   868 
   869 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   870 rule (as well as the assumption rule);
   871 
   872 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   873 lemmas, using the graph browser tool;
   874 
   875 * Pure: predict failure of "show" in interactive mode;
   876 
   877 * Pure: 'thms_containing' now takes actual terms as arguments;
   878 
   879 * HOL: improved method 'induct' --- now handles non-atomic goals
   880 (potential INCOMPATIBILITY); tuned error handling;
   881 
   882 * HOL: cases and induct rules now provide explicit hints about the
   883 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   884 any remaining facts are inserted into the goal verbatim;
   885 
   886 * HOL: local contexts (aka cases) may now contain term bindings as
   887 well; the 'cases' and 'induct' methods new provide a ?case binding for
   888 the result to be shown in each case;
   889 
   890 * HOL: added 'recdef_tc' command;
   891 
   892 * isatool convert assists in eliminating legacy ML scripts;
   893 
   894 
   895 *** HOL ***
   896 
   897 * HOL/Library: a collection of generic theories to be used together
   898 with main HOL; the theory loader path already includes this directory
   899 by default; the following existing theories have been moved here:
   900 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   901 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   902 
   903 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   904 modelling and verification task performed in Isabelle/HOL +
   905 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   906 
   907 * HOL/Algebra: special summation operator SUM no longer exists, it has
   908 been replaced by setsum; infix 'assoc' now has priority 50 (like
   909 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   910 'domain', this makes the theory consistent with mathematical
   911 literature;
   912 
   913 * HOL basics: added overloaded operations "inverse" and "divide"
   914 (infix "/"), syntax for generic "abs" operation, generic summation
   915 operator \<Sum>;
   916 
   917 * HOL/typedef: simplified package, provide more useful rules (see also
   918 HOL/subset.thy);
   919 
   920 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   921 now expressed as a proper nested rule (old-style tactic scripts may
   922 require atomize_strip_tac to cope with non-atomic premises);
   923 
   924 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   925 to "split_conv" (old name still available for compatibility);
   926 
   927 * HOL: improved concrete syntax for strings (e.g. allows translation
   928 rules with string literals);
   929 
   930 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   931  and Fleuriot's mechanization of analysis, including the transcendental
   932  functions for the reals;
   933 
   934 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   935 
   936 
   937 *** CTT ***
   938 
   939 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   940 "lam" is displayed as TWO lambda-symbols
   941 
   942 * CTT: theory Main now available, containing everything (that is, Bool
   943 and Arith);
   944 
   945 
   946 *** General ***
   947 
   948 * Pure: the Simplifier has been implemented properly as a derived rule
   949 outside of the actual kernel (at last!); the overall performance
   950 penalty in practical applications is about 50%, while reliability of
   951 the Isabelle inference kernel has been greatly improved;
   952 
   953 * print modes "brackets" and "no_brackets" control output of nested =>
   954 (types) and ==> (props); the default behaviour is "brackets";
   955 
   956 * Provers: fast_tac (and friends) now handle actual object-logic rules
   957 as assumptions as well;
   958 
   959 * system: support Poly/ML 4.0;
   960 
   961 * system: isatool install handles KDE version 1 or 2;
   962 
   963 
   964 
   965 New in Isabelle99-1 (October 2000)
   966 ----------------------------------
   967 
   968 *** Overview of INCOMPATIBILITIES ***
   969 
   970 * HOL: simplification of natural numbers is much changed; to partly
   971 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
   972 issue the following ML commands:
   973 
   974   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
   975   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
   976 
   977 * HOL: simplification no longer dives into case-expressions; this is
   978 controlled by "t.weak_case_cong" for each datatype t;
   979 
   980 * HOL: nat_less_induct renamed to less_induct;
   981 
   982 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
   983 fixsome to patch .thy and .ML sources automatically;
   984 
   985   select_equality  -> some_equality
   986   select_eq_Ex     -> some_eq_ex
   987   selectI2EX       -> someI2_ex
   988   selectI2         -> someI2
   989   selectI          -> someI
   990   select1_equality -> some1_equality
   991   Eps_sym_eq       -> some_sym_eq_trivial
   992   Eps_eq           -> some_eq_trivial
   993 
   994 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
   995 
   996 * HOL: removed obsolete theorem binding expand_if (refer to split_if
   997 instead);
   998 
   999 * HOL: the recursion equations generated by 'recdef' are now called
  1000 f.simps instead of f.rules;
  1001 
  1002 * HOL: qed_spec_mp now also handles bounded ALL as well;
  1003 
  1004 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  1005 sometimes be needed;
  1006 
  1007 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  1008 
  1009 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  1010 
  1011 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  1012 product is now "<*>" instead of "Times"; the lexicographic product is
  1013 now "<*lex*>" instead of "**";
  1014 
  1015 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  1016 of main HOL, but was unused); better use HOL's datatype package;
  1017 
  1018 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  1019 the old syntax may be recovered as follows:
  1020 
  1021   syntax (symbols)
  1022     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  1023       (infixl "\\<oplus>" 100)
  1024 
  1025 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1026 
  1027 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1028 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1029 internally;
  1030 
  1031 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1032 changed from A/r to A//r;
  1033 
  1034 * ZF: new treatment of arithmetic (nat & int) may break some old
  1035 proofs;
  1036 
  1037 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1038 rulify -> rule_format, elimify -> elim_format, ...);
  1039 
  1040 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1041 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1042 should have to change intro!! to intro? only); replaced "delrule" by
  1043 "rule del";
  1044 
  1045 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1046 
  1047 * Provers: strengthened force_tac by using new first_best_tac;
  1048 
  1049 * LaTeX document preparation: several changes of isabelle.sty (see
  1050 lib/texinputs);
  1051 
  1052 
  1053 *** Document preparation ***
  1054 
  1055 * formal comments (text blocks etc.) in new-style theories may now
  1056 contain antiquotations of thm/prop/term/typ/text to be presented
  1057 according to latex print mode; concrete syntax is like this:
  1058 @{term[show_types] "f(x) = a + x"};
  1059 
  1060 * isatool mkdir provides easy setup of Isabelle session directories,
  1061 including proper document sources;
  1062 
  1063 * generated LaTeX sources are now deleted after successful run
  1064 (isatool document -c); may retain a copy somewhere else via -D option
  1065 of isatool usedir;
  1066 
  1067 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1068 style files, achieving self-contained LaTeX sources and simplifying
  1069 LaTeX debugging;
  1070 
  1071 * old-style theories now produce (crude) LaTeX output as well;
  1072 
  1073 * browser info session directories are now self-contained (may be put
  1074 on WWW server seperately); improved graphs of nested sessions; removed
  1075 graph for 'all sessions';
  1076 
  1077 * several improvements in isabelle style files; \isabellestyle{it}
  1078 produces fake math mode output; \isamarkupheader is now \section by
  1079 default; see lib/texinputs/isabelle.sty etc.;
  1080 
  1081 
  1082 *** Isar ***
  1083 
  1084 * Isar/Pure: local results and corresponding term bindings are now
  1085 subject to Hindley-Milner polymorphism (similar to ML); this
  1086 accommodates incremental type-inference very nicely;
  1087 
  1088 * Isar/Pure: new derived language element 'obtain' supports
  1089 generalized existence reasoning;
  1090 
  1091 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1092 support accumulation of results, without applying any rules yet;
  1093 useful to collect intermediate results without explicit name
  1094 references, and for use with transitivity rules with more than 2
  1095 premises;
  1096 
  1097 * Isar/Pure: scalable support for case-analysis type proofs: new
  1098 'case' language element refers to local contexts symbolically, as
  1099 produced by certain proof methods; internally, case names are attached
  1100 to theorems as "tags";
  1101 
  1102 * Isar/Pure: theory command 'hide' removes declarations from
  1103 class/type/const name spaces;
  1104 
  1105 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1106 indicate potential overloading;
  1107 
  1108 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1109 
  1110 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1111 "{a,b,c}" instead of {a,b,c};
  1112 
  1113 * Isar/Pure now provides its own version of intro/elim/dest
  1114 attributes; useful for building new logics, but beware of confusion
  1115 with the version in Provers/classical;
  1116 
  1117 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1118 case name 'antecedent';
  1119 
  1120 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1121 to the current context is now done automatically);
  1122 
  1123 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1124 for definining proof methods in ML;
  1125 
  1126 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1127 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1128 most cases, one should have to change intro!! to intro? only);
  1129 replaced "delrule" by "rule del";
  1130 
  1131 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1132 'symmetric' attribute (the latter supercedes [RS sym]);
  1133 
  1134 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1135 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1136 well (including splits);
  1137 
  1138 * Isar/Provers: Simplifier and Classical methods now support all kind
  1139 of modifiers used in the past, including 'cong', 'iff', etc.
  1140 
  1141 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1142 of Simplifier and Classical reasoner);
  1143 
  1144 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1145 now support named cases; major packages (inductive, datatype, primrec,
  1146 recdef) support case names and properly name parameters;
  1147 
  1148 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1149 monotonicity conditions are extracted to be proven at end of
  1150 calculations;
  1151 
  1152 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1153 method anyway;
  1154 
  1155 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1156 split_if split_if_asm; datatype package provides theorems foo.splits =
  1157 foo.split foo.split_asm for each datatype;
  1158 
  1159 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1160 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1161 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1162 use "(cases (simplified))" method in proper proof texts);
  1163 
  1164 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1165 
  1166 * Isar: names of theorems etc. may be natural numbers as well;
  1167 
  1168 * Isar: 'pr' command: optional arguments for goals_limit and
  1169 ProofContext.prems_limit; no longer prints theory contexts, but only
  1170 proof states;
  1171 
  1172 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1173 additional print modes to be specified; e.g. "pr(latex)" will print
  1174 proof state according to the Isabelle LaTeX style;
  1175 
  1176 * Isar: improved support for emulating tactic scripts, including proof
  1177 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1178 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1179 (for HOL datatypes);
  1180 
  1181 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1182 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1183 'proof method scripts' have to be in depth-first order;
  1184 
  1185 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1186 
  1187 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1188 should instead use individual commands for printing items
  1189 (print_commands, print_methods etc.);
  1190 
  1191 * Isar: added 'nothing' --- the empty list of theorems;
  1192 
  1193 
  1194 *** HOL ***
  1195 
  1196 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1197 corresponding virtual machine and a specification of its bytecode
  1198 verifier and a lightweight bytecode verifier, including proofs of
  1199 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1200 Cornelia Pusch (see also the homepage of project Bali at
  1201 http://isabelle.in.tum.de/Bali/);
  1202 
  1203 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1204 Clemens Ballarin;
  1205 
  1206 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1207 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1208 Rasmussen;
  1209 
  1210 * HOL/Lattice: fundamental concepts of lattice theory and order
  1211 structures, including duals, properties of bounds versus algebraic
  1212 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1213 Theorem for complete lattices etc.; may also serve as a demonstration
  1214 for abstract algebraic reasoning using axiomatic type classes, and
  1215 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1216 
  1217 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1218 von Oheimb;
  1219 
  1220 * HOL/IMPP: extension of IMP with local variables and mutually
  1221 recursive procedures, by David von Oheimb;
  1222 
  1223 * HOL/Lambda: converted into new-style theory and document;
  1224 
  1225 * HOL/ex/Multiquote: example of multiple nested quotations and
  1226 anti-quotations -- basically a generalized version of de-Bruijn
  1227 representation; very useful in avoiding lifting of operations;
  1228 
  1229 * HOL/record: added general record equality rule to simpset; fixed
  1230 select-update simplification procedure to handle extended records as
  1231 well; admit "r" as field name;
  1232 
  1233 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1234 other numeric types and also as the identity of groups, rings, etc.;
  1235 
  1236 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1237 Types nat and int belong to this axclass;
  1238 
  1239 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1240    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1241    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1242   two terms #m*u and #n*u are replaced by #(m+n)*u
  1243     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1244   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1245     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1246 
  1247 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1248 powerful prover for predicate logic but knows nothing of clasets; see
  1249 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1250 
  1251 * HOL: new version of "case_tac" subsumes both boolean case split and
  1252 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1253 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1254 
  1255 * HOL: simplification no longer dives into case-expressions: only the
  1256 selector expression is simplified, but not the remaining arms; to
  1257 enable full simplification of case-expressions for datatype t, you may
  1258 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1259 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1260 
  1261 * HOL/recdef: the recursion equations generated by 'recdef' for
  1262 function 'f' are now called f.simps instead of f.rules; if all
  1263 termination conditions are proved automatically, these simplification
  1264 rules are added to the simpset, as in primrec; rules may be named
  1265 individually as well, resulting in a separate list of theorems for
  1266 each equation;
  1267 
  1268 * HOL/While is a new theory that provides a while-combinator. It
  1269 permits the definition of tail-recursive functions without the
  1270 provision of a termination measure. The latter is necessary once the
  1271 invariant proof rule for while is applied.
  1272 
  1273 * HOL: new (overloaded) notation for the set of elements below/above
  1274 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1275 
  1276 * HOL: theorems impI, allI, ballI bound as "strip";
  1277 
  1278 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1279 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1280 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1281 
  1282 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1283 
  1284 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1285 main HOL, but was unused);
  1286 
  1287 * HOL: fewer consts declared as global (e.g. have to refer to
  1288 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1289 
  1290 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1291 in case of overlap with user translations (e.g. judgements over
  1292 tuples); (note that the underlying logical represenation is still
  1293 bogus);
  1294 
  1295 
  1296 *** ZF ***
  1297 
  1298 * ZF: simplification automatically cancels common terms in arithmetic
  1299 expressions over nat and int;
  1300 
  1301 * ZF: new treatment of nat to minimize type-checking: all operators
  1302 coerce their operands to a natural number using the function natify,
  1303 making the algebraic laws unconditional;
  1304 
  1305 * ZF: as above, for int: operators coerce their operands to an integer
  1306 using the function intify;
  1307 
  1308 * ZF: the integer library now contains many of the usual laws for the
  1309 orderings, including $<=, and monotonicity laws for $+ and $*;
  1310 
  1311 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1312 simplification;
  1313 
  1314 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1315 to the simplifier and classical reasoner simultaneously;
  1316 
  1317 
  1318 *** General ***
  1319 
  1320 * Provers: blast_tac now handles actual object-logic rules as
  1321 assumptions; note that auto_tac uses blast_tac internally as well;
  1322 
  1323 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1324 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1325 
  1326 * Provers: delrules now handles destruct rules as well (no longer need
  1327 explicit make_elim);
  1328 
  1329 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1330   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1331 use instead the strong form,
  1332   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1333 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1334 from destruct-rules;
  1335 
  1336 * Provers: Simplifier.easy_setup provides a fast path to basic
  1337 Simplifier setup for new object-logics;
  1338 
  1339 * Pure: AST translation rules no longer require constant head on LHS;
  1340 
  1341 * Pure: improved name spaces: ambiguous output is qualified; support
  1342 for hiding of names;
  1343 
  1344 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1345 XSYMBOL_HOME; no longer need to do manual configuration in most
  1346 situations;
  1347 
  1348 * system: compression of ML heaps images may now be controlled via -c
  1349 option of isabelle and isatool usedir (currently only observed by
  1350 Poly/ML);
  1351 
  1352 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1353 useful for remote X11);
  1354 
  1355 * system: provide TAGS file for Isabelle sources;
  1356 
  1357 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1358 order;
  1359 
  1360 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1361 timing flag supersedes proof_timing and Toplevel.trace;
  1362 
  1363 * ML: new combinators |>> and |>>> for incremental transformations
  1364 with secondary results (e.g. certain theory extensions):
  1365 
  1366 * ML: PureThy.add_defs gets additional argument to indicate potential
  1367 overloading (usually false);
  1368 
  1369 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1370 results;
  1371 
  1372 
  1373 
  1374 New in Isabelle99 (October 1999)
  1375 --------------------------------
  1376 
  1377 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1378 
  1379 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1380 are no longer simplified.  (This allows the simplifier to unfold recursive
  1381 functional programs.)  To restore the old behaviour, declare
  1382 
  1383     Delcongs [if_weak_cong];
  1384 
  1385 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1386 complement;
  1387 
  1388 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1389 
  1390 * HOL/datatype: mutual_induct_tac no longer exists --
  1391   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1392 
  1393 * HOL/typedef: fixed type inference for representing set; type
  1394 arguments now have to occur explicitly on the rhs as type constraints;
  1395 
  1396 * ZF: The con_defs part of an inductive definition may no longer refer
  1397 to constants declared in the same theory;
  1398 
  1399 * HOL, ZF: the function mk_cases, generated by the inductive
  1400 definition package, has lost an argument.  To simplify its result, it
  1401 uses the default simpset instead of a supplied list of theorems.
  1402 
  1403 * HOL/List: the constructors of type list are now Nil and Cons;
  1404 
  1405 * Simplifier: the type of the infix ML functions
  1406         setSSolver addSSolver setSolver addSolver
  1407 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1408 for packaging solvers. A solver is created via
  1409         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1410 where the string argument is only a comment.
  1411 
  1412 
  1413 *** Proof tools ***
  1414 
  1415 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1416 decision procedure for linear arithmetic. Currently it is used for
  1417 types `nat', `int', and `real' in HOL (see below); it can, should and
  1418 will be instantiated for other types and logics as well.
  1419 
  1420 * The simplifier now accepts rewrite rules with flexible heads, eg
  1421      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1422   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1423   matching.
  1424 
  1425 
  1426 *** General ***
  1427 
  1428 * New Isabelle/Isar subsystem provides an alternative to traditional
  1429 tactical theorem proving; together with the ProofGeneral/isar user
  1430 interface it offers an interactive environment for developing human
  1431 readable proof documents (Isar == Intelligible semi-automated
  1432 reasoning); for further information see isatool doc isar-ref,
  1433 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1434 
  1435 * improved and simplified presentation of theories: better HTML markup
  1436 (including colors), graph views in several sizes; isatool usedir now
  1437 provides a proper interface for user theories (via -P option); actual
  1438 document preparation based on (PDF)LaTeX is available as well (for
  1439 new-style theories only); see isatool doc system for more information;
  1440 
  1441 * native support for Proof General, both for classic Isabelle and
  1442 Isabelle/Isar;
  1443 
  1444 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1445 using the graph browser tool;
  1446 
  1447 * Isabelle manuals now also available as PDF;
  1448 
  1449 * theory loader rewritten from scratch (may not be fully
  1450 bug-compatible); old loadpath variable has been replaced by show_path,
  1451 add_path, del_path, reset_path functions; new operations such as
  1452 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1453 isatool doc ref);
  1454 
  1455 * improved isatool install: option -k creates KDE application icon,
  1456 option -p DIR installs standalone binaries;
  1457 
  1458 * added ML_PLATFORM setting (useful for cross-platform installations);
  1459 more robust handling of platform specific ML images for SML/NJ;
  1460 
  1461 * the settings environment is now statically scoped, i.e. it is never
  1462 created again in sub-processes invoked from isabelle, isatool, or
  1463 Isabelle;
  1464 
  1465 * path element specification '~~' refers to '$ISABELLE_HOME';
  1466 
  1467 * in locales, the "assumes" and "defines" parts may be omitted if
  1468 empty;
  1469 
  1470 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1471 long arrows);
  1472 
  1473 * new print_mode "HTML";
  1474 
  1475 * new flag show_tags controls display of tags of theorems (which are
  1476 basically just comments that may be attached by some tools);
  1477 
  1478 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1479 mode and goal output format:
  1480 
  1481 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1482 244c244
  1483 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1484 ---
  1485 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1486 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1487 181c181
  1488 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1489 ---
  1490 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1491 
  1492 * function bind_thms stores lists of theorems (cf. bind_thm);
  1493 
  1494 * new shorthand tactics ftac, eatac, datac, fatac;
  1495 
  1496 * qed (and friends) now accept "" as result name; in that case the
  1497 theorem is not stored, but proper checks and presentation of the
  1498 result still apply;
  1499 
  1500 * theorem database now also indexes constants "Trueprop", "all",
  1501 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1502 
  1503 
  1504 *** HOL ***
  1505 
  1506 ** HOL arithmetic **
  1507 
  1508 * There are now decision procedures for linear arithmetic over nat and
  1509 int:
  1510 
  1511 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1512 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1513 are treated as atomic; subformulae not involving type `nat' or `int'
  1514 are ignored; quantified subformulae are ignored unless they are
  1515 positive universal or negative existential. The tactic has to be
  1516 invoked by hand and can be a little bit slow. In particular, the
  1517 running time is exponential in the number of occurrences of `min' and
  1518 `max', and `-' on `nat'.
  1519 
  1520 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1521 (negated) (in)equalities among the premises and the conclusion into
  1522 account (i.e. no compound formulae) and does not know about `min' and
  1523 `max', and `-' on `nat'. It is fast and is used automatically by the
  1524 simplifier.
  1525 
  1526 NB: At the moment, these decision procedures do not cope with mixed
  1527 nat/int formulae where the two parts interact, such as `m < n ==>
  1528 int(m) < int(n)'.
  1529 
  1530 * HOL/Numeral provides a generic theory of numerals (encoded
  1531 efficiently as bit strings); setup for types nat/int/real is in place;
  1532 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1533 int, existing theories and proof scripts may require a few additional
  1534 type constraints;
  1535 
  1536 * integer division and remainder can now be performed on constant
  1537 arguments;
  1538 
  1539 * many properties of integer multiplication, division and remainder
  1540 are now available;
  1541 
  1542 * An interface to the Stanford Validity Checker (SVC) is available through the
  1543 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1544 are proved automatically.  SVC must be installed separately, and its results
  1545 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1546 invocation of the underlying oracle).  For SVC see
  1547   http://verify.stanford.edu/SVC
  1548 
  1549 * IsaMakefile: the HOL-Real target now builds an actual image;
  1550 
  1551 
  1552 ** HOL misc **
  1553 
  1554 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1555 (in Isabelle/Isar) -- by Gertrud Bauer;
  1556 
  1557 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1558 analysis for assembly languages with subtypes;
  1559 
  1560 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1561 -- avoids syntactic ambiguities and treats state, transition, and
  1562 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1563 changed syntax and (many) tactics;
  1564 
  1565 * HOL/inductive: Now also handles more general introduction rules such
  1566   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1567   theorems are now maintained within the theory (maintained via the
  1568   "mono" attribute);
  1569 
  1570 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1571   (using function types) such as
  1572 
  1573   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1574 
  1575 * HOL/record: record_simproc (part of the default simpset) takes care
  1576 of selectors applied to updated records; record_split_tac is no longer
  1577 part of the default claset; update_defs may now be removed from the
  1578 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1579 
  1580   claset_ref () := claset() addSWrapper record_split_wrapper;
  1581   Delsimprocs [record_simproc]
  1582 
  1583 * HOL/typedef: fixed type inference for representing set; type
  1584 arguments now have to occur explicitly on the rhs as type constraints;
  1585 
  1586 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1587 names rather than an ML expression;
  1588 
  1589 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1590 supplied later.  Program schemes can be defined, such as
  1591     "While B C s = (if B s then While B C (C s) else s)"
  1592 where the well-founded relation can be chosen after B and C have been given.
  1593 
  1594 * HOL/List: the constructors of type list are now Nil and Cons;
  1595 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1596 course, ML tools referring to List.list.op # etc. have to be adapted;
  1597 
  1598 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1599 disabled by default; run isabelle with option -m HOL to get back to
  1600 the original Gordon/HOL-style output;
  1601 
  1602 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1603 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1604 
  1605 * HOL basic syntax simplified (more orthogonal): all variants of
  1606 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1607 Eps operator is provided as well: "SOME x. P[x]";
  1608 
  1609 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1610 
  1611 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1612 thus available for user theories;
  1613 
  1614 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1615 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1616 time;
  1617 
  1618 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1619 several times and then mp;
  1620 
  1621 
  1622 *** LK ***
  1623 
  1624 * the notation <<...>> is now available as a notation for sequences of
  1625 formulas;
  1626 
  1627 * the simplifier is now installed
  1628 
  1629 * the axiom system has been generalized (thanks to Soren Heilmann)
  1630 
  1631 * the classical reasoner now has a default rule database
  1632 
  1633 
  1634 *** ZF ***
  1635 
  1636 * new primrec section allows primitive recursive functions to be given
  1637 directly (as in HOL) over datatypes and the natural numbers;
  1638 
  1639 * new tactics induct_tac and exhaust_tac for induction (or case
  1640 analysis) over datatypes and the natural numbers;
  1641 
  1642 * the datatype declaration of type T now defines the recursor T_rec;
  1643 
  1644 * simplification automatically does freeness reasoning for datatype
  1645 constructors;
  1646 
  1647 * automatic type-inference, with AddTCs command to insert new
  1648 type-checking rules;
  1649 
  1650 * datatype introduction rules are now added as Safe Introduction rules
  1651 to the claset;
  1652 
  1653 * the syntax "if P then x else y" is now available in addition to
  1654 if(P,x,y);
  1655 
  1656 
  1657 *** Internal programming interfaces ***
  1658 
  1659 * tuned simplifier trace output; new flag debug_simp;
  1660 
  1661 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1662 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1663 
  1664 * AxClass.axclass_tac lost the theory argument;
  1665 
  1666 * tuned current_goals_markers semantics: begin / end goal avoids
  1667 printing empty lines;
  1668 
  1669 * removed prs and prs_fn hook, which was broken because it did not
  1670 include \n in its semantics, forcing writeln to add one
  1671 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1672 string -> unit if you really want to output text without newline;
  1673 
  1674 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1675 plain output, interface builders may have to enable 'isabelle_font'
  1676 mode to get Isabelle font glyphs as before;
  1677 
  1678 * refined token_translation interface; INCOMPATIBILITY: output length
  1679 now of type real instead of int;
  1680 
  1681 * theory loader actions may be traced via new ThyInfo.add_hook
  1682 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1683 your own database of information attached to *whole* theories -- as
  1684 opposed to intra-theory data slots offered via TheoryDataFun;
  1685 
  1686 * proper handling of dangling sort hypotheses (at last!);
  1687 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1688 extra sort hypotheses that can be witnessed from the type signature;
  1689 the force_strip_shyps flag is gone, any remaining shyps are simply
  1690 left in the theorem (with a warning issued by strip_shyps_warning);
  1691 
  1692 
  1693 
  1694 New in Isabelle98-1 (October 1998)
  1695 ----------------------------------
  1696 
  1697 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1698 
  1699 * several changes of automated proof tools;
  1700 
  1701 * HOL: major changes to the inductive and datatype packages, including
  1702 some minor incompatibilities of theory syntax;
  1703 
  1704 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1705 called `inj_on';
  1706 
  1707 * HOL: removed duplicate thms in Arith:
  1708   less_imp_add_less  should be replaced by  trans_less_add1
  1709   le_imp_add_le      should be replaced by  trans_le_add1
  1710 
  1711 * HOL: unary minus is now overloaded (new type constraints may be
  1712 required);
  1713 
  1714 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1715 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1716 now taken as an integer constant.
  1717 
  1718 * Pure: ML function 'theory_of' renamed to 'theory';
  1719 
  1720 
  1721 *** Proof tools ***
  1722 
  1723 * Simplifier:
  1724   1. Asm_full_simp_tac is now more aggressive.
  1725      1. It will sometimes reorient premises if that increases their power to
  1726         simplify.
  1727      2. It does no longer proceed strictly from left to right but may also
  1728         rotate premises to achieve further simplification.
  1729      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1730      old Asm_full_simp_tac in that it does not rotate premises.
  1731   2. The simplifier now knows a little bit about nat-arithmetic.
  1732 
  1733 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1734 allows for selected deletion of wrappers, by introduction of names for
  1735 wrapper functionals.  This implies that addbefore, addSbefore,
  1736 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1737 and that adding two tactics with the same name overwrites the first
  1738 one (emitting a warning).
  1739   type wrapper = (int -> tactic) -> (int -> tactic)
  1740   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1741   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1742   delWrapper, delSWrapper: claset *  string            -> claset
  1743   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1744 
  1745 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1746 semantics; addbefore now affects only the unsafe part of step_tac
  1747 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1748 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1749 by Force_tac;
  1750 
  1751 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1752 compWrapper; added safe wrapper (and access functions for it);
  1753 
  1754 * HOL/split_all_tac is now much faster and fails if there is nothing
  1755 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1756 and the names of the automatically generated variables have changed.
  1757 split_all_tac has moved within claset() from unsafe wrappers to safe
  1758 wrappers, which means that !!-bound variables are split much more
  1759 aggressively, and safe_tac and clarify_tac now split such variables.
  1760 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1761 Note: the same holds for record_split_tac, which does the job of
  1762 split_all_tac for record fields.
  1763 
  1764 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1765 permanently to the default simpset using Addsplits just like
  1766 Addsimps. They can be removed via Delsplits just like
  1767 Delsimps. Lower-case versions are also available.
  1768 
  1769 * HOL/Simplifier: The rule split_if is now part of the default
  1770 simpset. This means that the simplifier will eliminate all occurrences
  1771 of if-then-else in the conclusion of a goal. To prevent this, you can
  1772 either remove split_if completely from the default simpset by
  1773 `Delsplits [split_if]' or remove it in a specific call of the
  1774 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1775 other case splitting rules to/from the default simpset: every datatype
  1776 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1777 t is the name of the datatype).
  1778 
  1779 * Classical reasoner / Simplifier combination: new force_tac (and
  1780 derivatives Force_tac, force) combines rewriting and classical
  1781 reasoning (and whatever other tools) similarly to auto_tac, but is
  1782 aimed to solve the given subgoal completely.
  1783 
  1784 
  1785 *** General ***
  1786 
  1787 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1788 and `goalw': the theory is no longer needed as an explicit argument -
  1789 the current theory context is used; assumptions are no longer returned
  1790 at the ML-level unless one of them starts with ==> or !!; it is
  1791 recommended to convert to these new commands using isatool fixgoal
  1792 (backup your sources first!);
  1793 
  1794 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1795 the current theory context, and 'theory' to lookup stored theories;
  1796 
  1797 * new theory section 'locale' for declaring constants, assumptions and
  1798 definitions that have local scope;
  1799 
  1800 * new theory section 'nonterminals' for purely syntactic types;
  1801 
  1802 * new theory section 'setup' for generic ML setup functions
  1803 (e.g. package initialization);
  1804 
  1805 * the distribution now includes Isabelle icons: see
  1806 lib/logo/isabelle-{small,tiny}.xpm;
  1807 
  1808 * isatool install - install binaries with absolute references to
  1809 ISABELLE_HOME/bin;
  1810 
  1811 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1812 
  1813 * print mode 'emacs' reserved for Isamode;
  1814 
  1815 * support multiple print (ast) translations per constant name;
  1816 
  1817 * theorems involving oracles are now printed with a suffixed [!];
  1818 
  1819 
  1820 *** HOL ***
  1821 
  1822 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1823 
  1824 * HOL/inductive package reorganized and improved: now supports mutual
  1825 definitions such as
  1826 
  1827   inductive EVEN ODD
  1828     intrs
  1829       null "0 : EVEN"
  1830       oddI "n : EVEN ==> Suc n : ODD"
  1831       evenI "n : ODD ==> Suc n : EVEN"
  1832 
  1833 new theorem list "elims" contains an elimination rule for each of the
  1834 recursive sets; inductive definitions now handle disjunctive premises
  1835 correctly (also ZF);
  1836 
  1837 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1838 "mutual_induct" no longer exists - the induction rule is always
  1839 contained in "induct";
  1840 
  1841 
  1842 * HOL/datatype package re-implemented and greatly improved: now
  1843 supports mutually recursive datatypes such as
  1844 
  1845   datatype
  1846     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1847             | SUM ('a aexp) ('a aexp)
  1848             | DIFF ('a aexp) ('a aexp)
  1849             | NUM 'a
  1850   and
  1851     'a bexp = LESS ('a aexp) ('a aexp)
  1852             | AND ('a bexp) ('a bexp)
  1853             | OR ('a bexp) ('a bexp)
  1854 
  1855 as well as indirectly recursive datatypes such as
  1856 
  1857   datatype
  1858     ('a, 'b) term = Var 'a
  1859                   | App 'b ((('a, 'b) term) list)
  1860 
  1861 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1862 induction on mutually / indirectly recursive datatypes.
  1863 
  1864 Primrec equations are now stored in theory and can be accessed via
  1865 <function_name>.simps.
  1866 
  1867 INCOMPATIBILITIES:
  1868 
  1869   - Theories using datatypes must now have theory Datatype as an
  1870     ancestor.
  1871   - The specific <typename>.induct_tac no longer exists - use the
  1872     generic induct_tac instead.
  1873   - natE has been renamed to nat.exhaust - use exhaust_tac
  1874     instead of res_inst_tac ... natE. Note that the variable
  1875     names in nat.exhaust differ from the names in natE, this
  1876     may cause some "fragile" proofs to fail.
  1877   - The theorems split_<typename>_case and split_<typename>_case_asm
  1878     have been renamed to <typename>.split and <typename>.split_asm.
  1879   - Since default sorts of type variables are now handled correctly,
  1880     some datatype definitions may have to be annotated with explicit
  1881     sort constraints.
  1882   - Primrec definitions no longer require function name and type
  1883     of recursive argument.
  1884 
  1885 Consider using isatool fixdatatype to adapt your theories and proof
  1886 scripts to the new package (backup your sources first!).
  1887 
  1888 
  1889 * HOL/record package: considerably improved implementation; now
  1890 includes concrete syntax for record types, terms, updates; theorems
  1891 for surjective pairing and splitting !!-bound record variables; proof
  1892 support is as follows:
  1893 
  1894   1) standard conversions (selectors or updates applied to record
  1895 constructor terms) are part of the standard simpset;
  1896 
  1897   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1898 made part of standard simpset and claset via addIffs;
  1899 
  1900   3) a tactic for record field splitting (record_split_tac) is part of
  1901 the standard claset (addSWrapper);
  1902 
  1903 To get a better idea about these rules you may retrieve them via
  1904 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1905 the name of your record type.
  1906 
  1907 The split tactic 3) conceptually simplifies by the following rule:
  1908 
  1909   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1910 
  1911 Thus any record variable that is bound by meta-all will automatically
  1912 blow up into some record constructor term, consequently the
  1913 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1914 solve record problems automatically.
  1915 
  1916 
  1917 * reorganized the main HOL image: HOL/Integ and String loaded by
  1918 default; theory Main includes everything;
  1919 
  1920 * automatic simplification of integer sums and comparisons, using cancellation;
  1921 
  1922 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1923 
  1924 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1925 
  1926 * many new identities for unions, intersections, set difference, etc.;
  1927 
  1928 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1929 called split_if, split_split, split_sum_case and split_nat_case (to go
  1930 with add/delsplits);
  1931 
  1932 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1933 (?x::unit) = (); this is made part of the default simpset, which COULD
  1934 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1935 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1936 unit_abs_eta_conv is added in order to counter the effect of
  1937 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1938 %u.f();
  1939 
  1940 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1941 makes more sense);
  1942 
  1943 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1944   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1945   disjointness reasoning but breaking a few old proofs.
  1946 
  1947 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1948 to 'converse' from 'inverse' (for compatibility with ZF and some
  1949 literature);
  1950 
  1951 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1952 the well-founded relation;
  1953 
  1954 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1955     Compl A.  The "Compl" syntax remains available as input syntax for this
  1956     release ONLY.
  1957 
  1958 * HOL/Update: new theory of function updates:
  1959     f(a:=b) == %x. if x=a then b else f x
  1960 may also be iterated as in f(a:=b,c:=d,...);
  1961 
  1962 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1963 
  1964 * HOL/List:
  1965   - new function list_update written xs[i:=v] that updates the i-th
  1966     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1967   - new function `upt' written [i..j(] which generates the list
  1968     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1969     bound write [i..j], which is a shorthand for [i..j+1(].
  1970   - new lexicographic orderings and corresponding wellfoundedness theorems.
  1971 
  1972 * HOL/Arith:
  1973   - removed 'pred' (predecessor) function;
  1974   - generalized some theorems about n-1;
  1975   - many new laws about "div" and "mod";
  1976   - new laws about greatest common divisors (see theory ex/Primes);
  1977 
  1978 * HOL/Relation: renamed the relational operator r^-1 "converse"
  1979 instead of "inverse";
  1980 
  1981 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  1982   of the multiset ordering;
  1983 
  1984 * directory HOL/Real: a construction of the reals using Dedekind cuts
  1985   (not included by default);
  1986 
  1987 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  1988 
  1989 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  1990   programs, i.e. different program variables may have different types.
  1991 
  1992 * calling (stac rew i) now fails if "rew" has no effect on the goal
  1993   [previously, this check worked only if the rewrite rule was unconditional]
  1994   Now rew can involve either definitions or equalities (either == or =).
  1995 
  1996 
  1997 *** ZF ***
  1998 
  1999 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  2000   only the theorems proved on ZF.ML;
  2001 
  2002 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2003   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2004   disjointness reasoning but breaking a few old proofs.
  2005 
  2006 * ZF/Update: new theory of function updates
  2007     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  2008   may also be iterated as in f(a:=b,c:=d,...);
  2009 
  2010 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  2011 
  2012 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2013   [previously, this check worked only if the rewrite rule was unconditional]
  2014   Now rew can involve either definitions or equalities (either == or =).
  2015 
  2016 * case_tac provided for compatibility with HOL
  2017     (like the old excluded_middle_tac, but with subgoals swapped)
  2018 
  2019 
  2020 *** Internal programming interfaces ***
  2021 
  2022 * Pure: several new basic modules made available for general use, see
  2023 also src/Pure/README;
  2024 
  2025 * improved the theory data mechanism to support encapsulation (data
  2026 kind name replaced by private Object.kind, acting as authorization
  2027 key); new type-safe user interface via functor TheoryDataFun; generic
  2028 print_data function becomes basically useless;
  2029 
  2030 * removed global_names compatibility flag -- all theory declarations
  2031 are qualified by default;
  2032 
  2033 * module Pure/Syntax now offers quote / antiquote translation
  2034 functions (useful for Hoare logic etc. with implicit dependencies);
  2035 see HOL/ex/Antiquote for an example use;
  2036 
  2037 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2038 cterm -> thm;
  2039 
  2040 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2041 subgoal;
  2042 
  2043 * Display.print_goals function moved to Locale.print_goals;
  2044 
  2045 * standard print function for goals supports current_goals_markers
  2046 variable for marking begin of proof, end of proof, start of goal; the
  2047 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2048 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2049 for example;
  2050 
  2051 
  2052 
  2053 New in Isabelle98 (January 1998)
  2054 --------------------------------
  2055 
  2056 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2057 
  2058 * changed lexical syntax of terms / types: dots made part of long
  2059 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2060 
  2061 * simpset (and claset) reference variable replaced by functions
  2062 simpset / simpset_ref;
  2063 
  2064 * no longer supports theory aliases (via merge) and non-trivial
  2065 implicit merge of thms' signatures;
  2066 
  2067 * most internal names of constants changed due to qualified names;
  2068 
  2069 * changed Pure/Sequence interface (see Pure/seq.ML);
  2070 
  2071 
  2072 *** General Changes ***
  2073 
  2074 * hierachically structured name spaces (for consts, types, axms, thms
  2075 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2076 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2077 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2078 long_names for fully qualified output names; NOTE: ML programs
  2079 (special tactics, packages etc.) referring to internal names may have
  2080 to be adapted to cope with fully qualified names; in case of severe
  2081 backward campatibility problems try setting 'global_names' at compile
  2082 time to have enrything declared within a flat name space; one may also
  2083 fine tune name declarations in theories via the 'global' and 'local'
  2084 section;
  2085 
  2086 * reimplemented the implicit simpset and claset using the new anytype
  2087 data filed in signatures; references simpset:simpset ref etc. are
  2088 replaced by functions simpset:unit->simpset and
  2089 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2090 to patch your ML files accordingly;
  2091 
  2092 * HTML output now includes theory graph data for display with Java
  2093 applet or isatool browser; data generated automatically via isatool
  2094 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2095 
  2096 * defs may now be conditional; improved rewrite_goals_tac to handle
  2097 conditional equations;
  2098 
  2099 * defs now admits additional type arguments, using TYPE('a) syntax;
  2100 
  2101 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2102 creates a new theory node; implicit merge of thms' signatures is
  2103 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2104 transfer:theory->thm->thm in (rare) cases;
  2105 
  2106 * improved handling of draft signatures / theories; draft thms (and
  2107 ctyps, cterms) are automatically promoted to real ones;
  2108 
  2109 * slightly changed interfaces for oracles: admit many per theory, named
  2110 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2111 
  2112 * print_goals: optional output of const types (set show_consts and
  2113 show_types);
  2114 
  2115 * improved output of warnings (###) and errors (***);
  2116 
  2117 * subgoal_tac displays a warning if the new subgoal has type variables;
  2118 
  2119 * removed old README and Makefiles;
  2120 
  2121 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2122 
  2123 * removed obsolete init_pps and init_database;
  2124 
  2125 * deleted the obsolete tactical STATE, which was declared by
  2126     fun STATE tacfun st = tacfun st st;
  2127 
  2128 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2129 (which abbreviates $HOME);
  2130 
  2131 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2132 use isatool fixseq to adapt your ML programs (this works for fully
  2133 qualified references to the Sequence structure only!);
  2134 
  2135 * use_thy no longer requires writable current directory; it always
  2136 reloads .ML *and* .thy file, if either one is out of date;
  2137 
  2138 
  2139 *** Classical Reasoner ***
  2140 
  2141 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2142 tactics that use classical reasoning to simplify a subgoal without
  2143 splitting it into several subgoals;
  2144 
  2145 * Safe_tac: like safe_tac but uses the default claset;
  2146 
  2147 
  2148 *** Simplifier ***
  2149 
  2150 * added simplification meta rules:
  2151     (asm_)(full_)simplify: simpset -> thm -> thm;
  2152 
  2153 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2154 logics (again);
  2155 
  2156 * added prems argument to simplification procedures;
  2157 
  2158 * HOL, FOL, ZF: added infix function `addsplits':
  2159   instead of `<simpset> setloop (split_tac <thms>)'
  2160   you can simply write `<simpset> addsplits <thms>'
  2161 
  2162 
  2163 *** Syntax ***
  2164 
  2165 * TYPE('a) syntax for type reflection terms;
  2166 
  2167 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2168 
  2169 * pretty printer: changed order of mixfix annotation preference (again!);
  2170 
  2171 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2172 
  2173 
  2174 *** HOL ***
  2175 
  2176 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2177   with `addloop' of the simplifier to faciliate case splitting in premises.
  2178 
  2179 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2180 
  2181 * HOL/Auth: new protocol proofs including some for the Internet
  2182   protocol TLS;
  2183 
  2184 * HOL/Map: new theory of `maps' a la VDM;
  2185 
  2186 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2187 cancelling out common nat summands from =, <, <= (in)equalities, or
  2188 differences; simplification procedures nat_cancel_factor for
  2189 cancelling common factor from =, <, <= (in)equalities over natural
  2190 sums; nat_cancel contains both kinds of procedures, it is installed by
  2191 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2192 
  2193 * HOL/simplifier: terms of the form
  2194   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2195   are rewritten to
  2196   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2197   and those of the form
  2198   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2199   are rewritten to
  2200   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2201 
  2202 * HOL/datatype
  2203   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2204 
  2205   P(t_case f1 ... fn x) =
  2206      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2207         ...
  2208        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2209      )
  2210 
  2211   and a theorem `split_t_case_asm' of the form
  2212 
  2213   P(t_case f1 ... fn x) =
  2214     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2215         ...
  2216        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2217      )
  2218   which can be added to a simpset via `addsplits'. The existing theorems
  2219   expand_list_case and expand_option_case have been renamed to
  2220   split_list_case and split_option_case.
  2221 
  2222 * HOL/Arithmetic:
  2223   - `pred n' is automatically converted to `n-1'.
  2224     Users are strongly encouraged not to use `pred' any longer,
  2225     because it will disappear altogether at some point.
  2226   - Users are strongly encouraged to write "0 < n" rather than
  2227     "n ~= 0". Theorems and proof tools have been modified towards this
  2228     `standard'.
  2229 
  2230 * HOL/Lists:
  2231   the function "set_of_list" has been renamed "set" (and its theorems too);
  2232   the function "nth" now takes its arguments in the reverse order and
  2233   has acquired the infix notation "!" as in "xs!n".
  2234 
  2235 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2236 
  2237 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2238   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2239 
  2240 * HOL/record: extensible records with schematic structural subtyping
  2241 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2242 still lacks various theorems and concrete record syntax;
  2243 
  2244 
  2245 *** HOLCF ***
  2246 
  2247 * removed "axioms" and "generated by" sections;
  2248 
  2249 * replaced "ops" section by extended "consts" section, which is capable of
  2250   handling the continuous function space "->" directly;
  2251 
  2252 * domain package:
  2253   . proves theorems immediately and stores them in the theory,
  2254   . creates hierachical name space,
  2255   . now uses normal mixfix annotations (instead of cinfix...),
  2256   . minor changes to some names and values (for consistency),
  2257   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2258   . separator between mutual domain defs: changed "," to "and",
  2259   . improved handling of sort constraints;  now they have to
  2260     appear on the left-hand side of the equations only;
  2261 
  2262 * fixed LAM <x,y,zs>.b syntax;
  2263 
  2264 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2265 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2266 
  2267 
  2268 *** FOL and ZF ***
  2269 
  2270 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2271   with `addloop' of the simplifier to faciliate case splitting in premises.
  2272 
  2273 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2274 in HOL, they strip ALL and --> from proved theorems;
  2275 
  2276 
  2277 
  2278 New in Isabelle94-8 (May 1997)
  2279 ------------------------------
  2280 
  2281 *** General Changes ***
  2282 
  2283 * new utilities to build / run / maintain Isabelle etc. (in parts
  2284 still somewhat experimental); old Makefiles etc. still functional;
  2285 
  2286 * new 'Isabelle System Manual';
  2287 
  2288 * INSTALL text, together with ./configure and ./build scripts;
  2289 
  2290 * reimplemented type inference for greater efficiency, better error
  2291 messages and clean internal interface;
  2292 
  2293 * prlim command for dealing with lots of subgoals (an easier way of
  2294 setting goals_limit);
  2295 
  2296 
  2297 *** Syntax ***
  2298 
  2299 * supports alternative (named) syntax tables (parser and pretty
  2300 printer); internal interface is provided by add_modesyntax(_i);
  2301 
  2302 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2303 be used in conjunction with the Isabelle symbol font; uses the
  2304 "symbols" syntax table;
  2305 
  2306 * added token_translation interface (may translate name tokens in
  2307 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2308 the current print_mode); IMPORTANT: user print translation functions
  2309 are responsible for marking newly introduced bounds
  2310 (Syntax.mark_boundT);
  2311 
  2312 * token translations for modes "xterm" and "xterm_color" that display
  2313 names in bold, underline etc. or colors (which requires a color
  2314 version of xterm);
  2315 
  2316 * infixes may now be declared with names independent of their syntax;
  2317 
  2318 * added typed_print_translation (like print_translation, but may
  2319 access type of constant);
  2320 
  2321 
  2322 *** Classical Reasoner ***
  2323 
  2324 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2325 some limitations.  Blast_tac...
  2326   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2327   + ignores elimination rules that don't have the correct format
  2328         (the conclusion MUST be a formula variable)
  2329   + ignores types, which can make HOL proofs fail
  2330   + rules must not require higher-order unification, e.g. apply_type in ZF
  2331     [message "Function Var's argument not a bound variable" relates to this]
  2332   + its proof strategy is more general but can actually be slower
  2333 
  2334 * substitution with equality assumptions no longer permutes other
  2335 assumptions;
  2336 
  2337 * minor changes in semantics of addafter (now called addaltern); renamed
  2338 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2339 (and access functions for it);
  2340 
  2341 * improved combination of classical reasoner and simplifier:
  2342   + functions for handling clasimpsets
  2343   + improvement of addss: now the simplifier is called _after_ the
  2344     safe steps.
  2345   + safe variant of addss called addSss: uses safe simplifications
  2346     _during_ the safe steps. It is more complete as it allows multiple
  2347     instantiations of unknowns (e.g. with slow_tac).
  2348 
  2349 *** Simplifier ***
  2350 
  2351 * added interface for simplification procedures (functions that
  2352 produce *proven* rewrite rules on the fly, depending on current
  2353 redex);
  2354 
  2355 * ordering on terms as parameter (used for ordered rewriting);
  2356 
  2357 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2358 
  2359 * the solver is now split into a safe and an unsafe part.
  2360 This should be invisible for the normal user, except that the
  2361 functions setsolver and addsolver have been renamed to setSolver and
  2362 addSolver; added safe_asm_full_simp_tac;
  2363 
  2364 
  2365 *** HOL ***
  2366 
  2367 * a generic induction tactic `induct_tac' which works for all datatypes and
  2368 also for type `nat';
  2369 
  2370 * a generic case distinction tactic `exhaust_tac' which works for all
  2371 datatypes and also for type `nat';
  2372 
  2373 * each datatype comes with a function `size';
  2374 
  2375 * patterns in case expressions allow tuple patterns as arguments to
  2376 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2377 
  2378 * primrec now also works with type nat;
  2379 
  2380 * recdef: a new declaration form, allows general recursive functions to be
  2381 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2382 
  2383 * the constant for negation has been renamed from "not" to "Not" to
  2384 harmonize with FOL, ZF, LK, etc.;
  2385 
  2386 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2387 infinite lists;
  2388 
  2389 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2390 
  2391 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2392 problems in commutative rings, using axiomatic type classes for + and *;
  2393 
  2394 * more examples in HOL/MiniML and HOL/Auth;
  2395 
  2396 * more default rewrite rules for quantifiers, union/intersection;
  2397 
  2398 * a new constant `arbitrary == @x.False';
  2399 
  2400 * HOLCF/IOA replaces old HOL/IOA;
  2401 
  2402 * HOLCF changes: derived all rules and arities
  2403   + axiomatic type classes instead of classes
  2404   + typedef instead of faking type definitions
  2405   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2406   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2407   + eliminated the types void, one, tr
  2408   + use unit lift and bool lift (with translations) instead of one and tr
  2409   + eliminated blift from Lift3.thy (use Def instead of blift)
  2410   all eliminated rules are derived as theorems --> no visible changes ;
  2411 
  2412 
  2413 *** ZF ***
  2414 
  2415 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2416 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2417 as ZF_cs addSIs [equalityI];
  2418 
  2419 
  2420 
  2421 New in Isabelle94-7 (November 96)
  2422 ---------------------------------
  2423 
  2424 * allowing negative levels (as offsets) in prlev and choplev;
  2425 
  2426 * super-linear speedup for large simplifications;
  2427 
  2428 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2429 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2430 FAIL); can suppress it using the command Delsimps (ex_simps @
  2431 all_simps); De Morgan laws are also now included, by default;
  2432 
  2433 * improved printing of ==>  :  ~:
  2434 
  2435 * new object-logic "Sequents" adds linear logic, while replacing LK
  2436 and Modal (thanks to Sara Kalvala);
  2437 
  2438 * HOL/Auth: correctness proofs for authentication protocols;
  2439 
  2440 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2441 examples on HOL/Auth);
  2442 
  2443 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2444 the rewriter and classical reasoner simultaneously;
  2445 
  2446 * function uresult no longer returns theorems in "standard" format;
  2447 regain previous version by: val uresult = standard o uresult;
  2448 
  2449 
  2450 
  2451 New in Isabelle94-6
  2452 -------------------
  2453 
  2454 * oracles -- these establish an interface between Isabelle and trusted
  2455 external reasoners, which may deliver results as theorems;
  2456 
  2457 * proof objects (in particular record all uses of oracles);
  2458 
  2459 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2460 
  2461 * "constdefs" section in theory files;
  2462 
  2463 * "primrec" section (HOL) no longer requires names;
  2464 
  2465 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2466 
  2467 
  2468 
  2469 New in Isabelle94-5
  2470 -------------------
  2471 
  2472 * reduced space requirements;
  2473 
  2474 * automatic HTML generation from theories;
  2475 
  2476 * theory files no longer require "..." (quotes) around most types;
  2477 
  2478 * new examples, including two proofs of the Church-Rosser theorem;
  2479 
  2480 * non-curried (1994) version of HOL is no longer distributed;
  2481 
  2482 
  2483 
  2484 New in Isabelle94-4
  2485 -------------------
  2486 
  2487 * greatly reduced space requirements;
  2488 
  2489 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2490 
  2491 * searchable theorem database (see the section "Retrieving theorems" on
  2492 page 8 of the Reference Manual);
  2493 
  2494 * new examples, including Grabczewski's monumental case study of the
  2495 Axiom of Choice;
  2496 
  2497 * The previous version of HOL renamed to Old_HOL;
  2498 
  2499 * The new version of HOL (previously called CHOL) uses a curried syntax
  2500 for functions.  Application looks like f a b instead of f(a,b);
  2501 
  2502 * Mutually recursive inductive definitions finally work in HOL;
  2503 
  2504 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2505 translates to the operator "split";
  2506 
  2507 
  2508 
  2509 New in Isabelle94-3
  2510 -------------------
  2511 
  2512 * new infix operator, addss, allowing the classical reasoner to
  2513 perform simplification at each step of its search.  Example:
  2514         fast_tac (cs addss ss)
  2515 
  2516 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2517 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2518 look like (a,b) instead of <a,b>;
  2519 
  2520 * PLEASE NOTE: CHOL will eventually replace HOL!
  2521 
  2522 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2523 It translates to the operator "split".  A new theory of integers is available;
  2524 
  2525 * In ZF, integer numerals now denote two's-complement binary integers.
  2526 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2527 
  2528 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2529 of the Axiom of Choice;
  2530 
  2531 
  2532 
  2533 New in Isabelle94-2
  2534 -------------------
  2535 
  2536 * Significantly faster resolution;
  2537 
  2538 * the different sections in a .thy file can now be mixed and repeated
  2539 freely;
  2540 
  2541 * Database of theorems for FOL, HOL and ZF.  New
  2542 commands including qed, qed_goal and bind_thm store theorems in the database.
  2543 
  2544 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2545 a given theory (thms_of), or find out what theory a theorem was proved in
  2546 (theory_of_thm);
  2547 
  2548 * Bugs fixed in the inductive definition and datatype packages;
  2549 
  2550 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2551 and HOL_dup_cs obsolete;
  2552 
  2553 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2554 have been removed;
  2555 
  2556 * Simpler definition of function space in ZF;
  2557 
  2558 * new results about cardinal and ordinal arithmetic in ZF;
  2559 
  2560 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2561 types;
  2562 
  2563 
  2564 $Id$