NEWS
author ballarin
Fri Apr 02 14:08:30 2004 +0200 (2004-04-02)
changeset 14508 859b11514537
parent 14503 255ad604e08e
child 14536 43e436a4f293
permissions -rw-r--r--
Experimental command for instantiation of locales in proof contexts:
instantiate <label>: <loc>
     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 * Pure: It is now illegal to specify Theory.ML explicitly as a dependency
    49   in the files section of the theory Theory. (This is more of a diagnostic
    50   than a restriction, as the theory loader screws up if Theory.ML is manually
    51   loaded.)
    52 
    53 *** Isar ***
    54 
    55 * Tactic emulation methods rule_tac, erule_tac, drule_tac, frule_tac,
    56   cut_tac, subgoal_tac and thin_tac:
    57   - Now understand static (Isar) contexts.  As a consequence, users of Isar
    58     locales are no longer forced to write Isar proof scripts.
    59     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
    60     emulations.
    61   - INCOMPATIBILITY: names of variables to be instantiated may no
    62     longer be enclosed in quotes.  Instead, precede variable name with `?'.
    63     This is consistent with the instantiation attribute "where".
    64 
    65 * Attributes "where" and "of":
    66   - Now take type variables of instantiated theorem into account when reading
    67     the instantiation string.  This fixes a bug that caused instantiated
    68     theorems to have too special types in some circumstances.
    69   - "where" permits explicit instantiations of type variables.
    70 
    71 * Calculation commands "moreover" and "also":
    72   Do not reset facts ("this") any more.
    73 
    74 * Locales:
    75   - Goal statements involving the context element "includes" no longer
    76     generate theorems with internal delta predicates (those ending on
    77     "_axioms") in the premise.
    78     Resolve particular premise with <locale>.intro to obtain old form.
    79   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
    80     specification and "includes" elements in goal statement.
    81   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
    82     [intro?] and [elim?] (respectively) by default.
    83   - Experimental command for instantiation of locales in proof contexts:
    84         instantiate <label>: <loc>
    85     Instantiates locale <loc> and adds all its theorems to the current context
    86     taking into account their attributes, and qualifying their names with
    87     <label>.  If the locale has assumptions, a chained fact of the form
    88     "<loc> t1 ... tn" is expected from which instantiations of the parameters
    89     are derived.
    90     A few (very simple) examples can be found in FOL/ex/LocaleInst.thy.
    91 
    92 * HOL: Tactic emulation methods induct_tac and case_tac understand static
    93   (Isar) contexts.
    94 
    95 *** HOL ***
    96 
    97 * Simplifier:
    98   - Much improved handling of linear and partial orders.
    99     Reasoners for linear and partial orders are set up for type classes
   100     "linorder" and "order" respectively, and are added to the default simpset
   101     as solvers.  This means that the simplifier can build transitivity chains
   102     to solve goals from the assumptions.
   103   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications
   104     of blast or auto after simplification become unnecessary because the goal
   105     is solved by simplification already.
   106 
   107 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws, 
   108     all proved in axiomatic type classes for semirings, rings and fields.
   109 
   110 * Numerics:
   111   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are
   112     now formalized using the Ring_and_Field theory mentioned above. 
   113   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently
   114     than before, because now they are set up once in a generic manner.
   115   - INCOMPATIBILITY: many type-specific arithmetic laws have gone. 
   116     Look for the general versions in Ring_and_Field (and Power if they concern
   117     exponentiation).
   118 
   119 * Type "rat" of the rational numbers is now available in HOL-Complex.
   120 
   121 * Records:
   122   - Record types are now by default printed with their type abbreviation
   123     instead of the list of all field types. This can be configured via
   124     the reference "print_record_type_abbr".
   125   - Simproc "record_upd_simproc" for simplification of multiple updates added 
   126     (not enabled by default).
   127   - Simproc "record_ex_sel_eq_simproc" to simplify EX x. sel r = x resp.
   128     EX x. x = sel r to True (not enabled by default).
   129   - Tactic "record_split_simp_tac" to split and simplify records added.
   130  
   131 * 'specification' command added, allowing for definition by
   132   specification.  There is also an 'ax_specification' command that
   133   introduces the new constants axiomatically.
   134 
   135 * arith(_tac) is now able to generate counterexamples for reals as well.
   136 
   137 * HOL-Algebra: new locale "ring" for non-commutative rings.
   138 
   139 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
   140  defintions, thanks to Sava Krsti\'{c} and John Matthews.
   141 
   142 * Unions and Intersections:
   143   The x-symbol output syntax of UN and INT has been changed
   144   from "\<Union>x \<in> A. B" to "\<Union\<^bsub>x \<in> A\<^esub> B"
   145   i.e. the index formulae has become a subscript, like in normal math.
   146   Similarly for "\<Union>x. B", and for \<Inter> instead of \<Union>.
   147   The subscript version is also accepted as input syntax.
   148 
   149 * Unions and Intersections over Intervals:
   150   There is new short syntax "UN i<=n. A" for "UN i:{0..n}. A". There is 
   151   also an x-symbol version with subscripts "\<Union>\<^bsub>i <= n\<^esub>. A" 
   152   like in normal math, and corresponding versions for < and for intersection.
   153 
   154 * ML: the legacy theory structures Int and List have been removed. They had
   155   conflicted with ML Basis Library structures having the same names.
   156 
   157 * 'refute' command added to search for (finite) countermodels.  Only works
   158   for a fragment of HOL.  The installation of an external SAT solver is
   159   highly recommended.  See "HOL/Refute.thy" for details.
   160 
   161 
   162 New in Isabelle2003 (May 2003)
   163 --------------------------------
   164 
   165 *** General ***
   166 
   167 * Provers/simplifier:
   168 
   169   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   170     Assumptions are now subject to complete mutual simplification,
   171     not just from left to right. The simplifier now preserves
   172     the order of assumptions.
   173 
   174     Potential INCOMPATIBILITY:
   175 
   176     -- simp sometimes diverges where the old version did
   177        not, e.g. invoking simp on the goal
   178 
   179         [| P (f x); y = x; f x = f y |] ==> Q
   180 
   181        now gives rise to the infinite reduction sequence
   182 
   183         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   184 
   185        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   186        kind of problem.
   187 
   188     -- Tactics combining classical reasoner and simplification (such as auto)
   189        are also affected by this change, because many of them rely on
   190        simp. They may sometimes diverge as well or yield a different numbers
   191        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   192        in case of problems. Sometimes subsequent calls to the classical
   193        reasoner will fail because a preceeding call to the simplifier too
   194        eagerly simplified the goal, e.g. deleted redundant premises.
   195 
   196   - The simplifier trace now shows the names of the applied rewrite rules
   197 
   198   - You can limit the number of recursive invocations of the simplifier
   199     during conditional rewriting (where the simplifie tries to solve the
   200     conditions before applying the rewrite rule):
   201     ML "simp_depth_limit := n"
   202     where n is an integer. Thus you can force termination where previously
   203     the simplifier would diverge.
   204 
   205   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   206 
   207   - No longer aborts on failed congruence proof.  Instead, the
   208     congruence is ignored.
   209 
   210 * Pure: New generic framework for extracting programs from constructive
   211   proofs. See HOL/Extraction.thy for an example instantiation, as well
   212   as HOL/Extraction for some case studies.
   213 
   214 * Pure: The main goal of the proof state is no longer shown by default, only
   215 the subgoals. This behaviour is controlled by a new flag.
   216    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   217 (ML: Proof.show_main_goal).
   218 
   219 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   220 rules whose conclusion matches subgoal 1:
   221       PG menu: Isabelle/Isar -> Show me -> matching rules
   222 The rules are ordered by how closely they match the subgoal.
   223 In particular, rules that solve a subgoal outright are displayed first
   224 (or rather last, the way they are printed).
   225 (ML: ProofGeneral.print_intros())
   226 
   227 * Pure: New flag trace_unify_fail causes unification to print
   228 diagnostic information (PG: in trace buffer) when it fails. This is
   229 useful for figuring out why single step proofs like rule, erule or
   230 assumption failed.
   231 
   232 * Pure: Locale specifications now produce predicate definitions
   233 according to the body of text (covering assumptions modulo local
   234 definitions); predicate "loc_axioms" covers newly introduced text,
   235 while "loc" is cumulative wrt. all included locale expressions; the
   236 latter view is presented only on export into the global theory
   237 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   238 on the old view without predicates;
   239 
   240 * Pure: predefined locales "var" and "struct" are useful for sharing
   241 parameters (as in CASL, for example); just specify something like
   242 ``var x + var y + struct M'' as import;
   243 
   244 * Pure: improved thms_containing: proper indexing of facts instead of
   245 raw theorems; check validity of results wrt. current name space;
   246 include local facts of proof configuration (also covers active
   247 locales), cover fixed variables in index; may use "_" in term
   248 specification; an optional limit for the number of printed facts may
   249 be given (the default is 40);
   250 
   251 * Pure: disallow duplicate fact bindings within new-style theory files
   252 (batch-mode only);
   253 
   254 * Provers: improved induct method: assumptions introduced by case
   255 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   256 the goal statement); "foo" still refers to all facts collectively;
   257 
   258 * Provers: the function blast.overloaded has been removed: all constants
   259 are regarded as potentially overloaded, which improves robustness in exchange
   260 for slight decrease in efficiency;
   261 
   262 * Provers/linorder: New generic prover for transitivity reasoning over
   263 linear orders.  Note: this prover is not efficient!
   264 
   265 * Isar: preview of problems to finish 'show' now produce an error
   266 rather than just a warning (in interactive mode);
   267 
   268 
   269 *** HOL ***
   270 
   271 * arith(_tac)
   272 
   273  - Produces a counter example if it cannot prove a goal.
   274    Note that the counter example may be spurious if the goal is not a formula
   275    of quantifier-free linear arithmetic.
   276    In ProofGeneral the counter example appears in the trace buffer.
   277 
   278  - Knows about div k and mod k where k is a numeral of type nat or int.
   279 
   280  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   281    linear arithmetic fails. This takes account of quantifiers and divisibility.
   282    Presburger arithmetic can also be called explicitly via presburger(_tac). 
   283 
   284 * simp's arithmetic capabilities have been enhanced a bit: it now
   285 takes ~= in premises into account (by performing a case split);
   286 
   287 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   288 are distributed over a sum of terms;
   289 
   290 * New tactic "trans_tac" and method "trans" instantiate
   291 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   292 "<=", "<" and "="). 
   293 
   294 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main 
   295 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   296 
   297 * 'typedef' command has new option "open" to suppress the set
   298 definition;
   299 
   300 * functions Min and Max on finite sets have been introduced (theory
   301 Finite_Set);
   302 
   303 * attribute [symmetric] now works for relations as well; it turns
   304 (x,y) : R^-1 into (y,x) : R, and vice versa;
   305 
   306 * induct over a !!-quantified statement (say !!x1..xn):
   307   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   308 
   309 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   310 %x. None. Warning: empty_def now refers to the previously hidden definition
   311 of the empty set.
   312 
   313 * Algebra: formalization of classical algebra.  Intended as base for
   314 any algebraic development in Isabelle.  Currently covers group theory
   315 (up to Sylow's theorem) and ring theory (Universal Property of
   316 Univariate Polynomials).  Contributions welcome;
   317 
   318 * GroupTheory: deleted, since its material has been moved to Algebra;
   319 
   320 * Complex: new directory of the complex numbers with numeric constants, 
   321 nonstandard complex numbers, and some complex analysis, standard and 
   322 nonstandard (Jacques Fleuriot);
   323 
   324 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   325 
   326 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques 
   327 Fleuriot);
   328 
   329 * Real/HahnBanach: updated and adapted to locales;
   330 
   331 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   332 Gray and Kramer);
   333 
   334 * UNITY: added the Meier-Sanders theory of progress sets;
   335 
   336 * MicroJava: bytecode verifier and lightweight bytecode verifier
   337 as abstract algorithms, instantiated to the JVM;
   338 
   339 * Bali: Java source language formalization. Type system, operational
   340 semantics, axiomatic semantics. Supported language features:
   341 classes, interfaces, objects,virtual methods, static methods,
   342 static/instance fields, arrays, access modifiers, definite
   343 assignment, exceptions.
   344 
   345 
   346 *** ZF ***
   347 
   348 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   349 universe, etc.);
   350 
   351 * Main ZF: virtually all theories converted to new-style format;
   352 
   353 
   354 *** ML ***
   355 
   356 * Pure: Tactic.prove provides sane interface for internal proofs;
   357 omits the infamous "standard" operation, so this is more appropriate
   358 than prove_goalw_cterm in many situations (e.g. in simprocs);
   359 
   360 * Pure: improved error reporting of simprocs;
   361 
   362 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   363 up simprocs;
   364 
   365 
   366 *** Document preparation ***
   367 
   368 * uses \par instead of \\ for line breaks in theory text. This may
   369 shift some page breaks in large documents. To get the old behaviour
   370 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   371 
   372 * minimized dependencies of isabelle.sty and isabellesym.sty on 
   373 other packages
   374 
   375 * \<euro> now needs package babel/greek instead of marvosym (which
   376 broke \Rightarrow)
   377 
   378 * normal size for \<zero>...\<nine> (uses \mathbf instead of 
   379 textcomp package)
   380 
   381 
   382 New in Isabelle2002 (March 2002)
   383 --------------------------------
   384 
   385 *** Document preparation ***
   386 
   387 * greatly simplified document preparation setup, including more
   388 graceful interpretation of isatool usedir -i/-d/-D options, and more
   389 instructive isatool mkdir; users should basically be able to get
   390 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   391 users may run a separate document processing stage manually like this:
   392 "isatool usedir -D output HOL Test && isatool document Test/output";
   393 
   394 * theory dependency graph may now be incorporated into documents;
   395 isatool usedir -g true will produce session_graph.eps/.pdf for use
   396 with \includegraphics of LaTeX;
   397 
   398 * proper spacing of consecutive markup elements, especially text
   399 blocks after section headings;
   400 
   401 * support bold style (for single symbols only), input syntax is like
   402 this: "\<^bold>\<alpha>" or "\<^bold>A";
   403 
   404 * \<bullet> is now output as bold \cdot by default, which looks much
   405 better in printed text;
   406 
   407 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   408 note that these symbols are currently unavailable in Proof General /
   409 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   410 
   411 * isatool latex no longer depends on changed TEXINPUTS, instead
   412 isatool document copies the Isabelle style files to the target
   413 location;
   414 
   415 
   416 *** Isar ***
   417 
   418 * Pure/Provers: improved proof by cases and induction;
   419   - 'case' command admits impromptu naming of parameters (such as
   420     "case (Suc n)");
   421   - 'induct' method divinates rule instantiation from the inductive
   422     claim; no longer requires excessive ?P bindings for proper
   423     instantiation of cases;
   424   - 'induct' method properly enumerates all possibilities of set/type
   425     rules; as a consequence facts may be also passed through *type*
   426     rules without further ado;
   427   - 'induct' method now derives symbolic cases from the *rulified*
   428     rule (before it used to rulify cases stemming from the internal
   429     atomized version); this means that the context of a non-atomic
   430     statement becomes is included in the hypothesis, avoiding the
   431     slightly cumbersome show "PROP ?case" form;
   432   - 'induct' may now use elim-style induction rules without chaining
   433     facts, using ``missing'' premises from the goal state; this allows
   434     rules stemming from inductive sets to be applied in unstructured
   435     scripts, while still benefitting from proper handling of non-atomic
   436     statements; NB: major inductive premises need to be put first, all
   437     the rest of the goal is passed through the induction;
   438   - 'induct' proper support for mutual induction involving non-atomic
   439     rule statements (uses the new concept of simultaneous goals, see
   440     below);
   441   - append all possible rule selections, but only use the first
   442     success (no backtracking);
   443   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   444   - undeclared rule case names default to numbers 1, 2, 3, ...;
   445   - added 'print_induct_rules' (covered by help item in recent Proof
   446     General versions);
   447   - moved induct/cases attributes to Pure, methods to Provers;
   448   - generic method setup instantiated for FOL and HOL;
   449 
   450 * Pure: support multiple simultaneous goal statements, for example
   451 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   452 meta-level mechanism, this acts as if several individual goals had
   453 been stated separately; in particular common proof methods need to be
   454 repeated in order to cover all claims; note that a single elimination
   455 step is *not* sufficient to establish the two conjunctions, so this
   456 fails:
   457 
   458   assume "A & B" then have A and B ..   (*".." fails*)
   459 
   460 better use "obtain" in situations as above; alternative refer to
   461 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   462 
   463 * Pure: proper integration with ``locales''; unlike the original
   464 version by Florian Kammüller, Isar locales package high-level proof
   465 contexts rather than raw logical ones (e.g. we admit to include
   466 attributes everywhere); operations on locales include merge and
   467 rename; support for implicit arguments (``structures''); simultaneous
   468 type-inference over imports and text; see also HOL/ex/Locales.thy for
   469 some examples;
   470 
   471 * Pure: the following commands have been ``localized'', supporting a
   472 target locale specification "(in name)": 'lemma', 'theorem',
   473 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   474 stored both within the locale and at the theory level (exported and
   475 qualified by the locale name);
   476 
   477 * Pure: theory goals may now be specified in ``long'' form, with
   478 ad-hoc contexts consisting of arbitrary locale elements. for example
   479 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   480 definitions may be given, too); the result is a meta-level rule with
   481 the context elements being discharged in the obvious way;
   482 
   483 * Pure: new proof command 'using' allows to augment currently used
   484 facts after a goal statement ('using' is syntactically analogous to
   485 'apply', but acts on the goal's facts only); this allows chained facts
   486 to be separated into parts given before and after a claim, as in
   487 ``from a and b have C using d and e <proof>'';
   488 
   489 * Pure: renamed "antecedent" case to "rule_context";
   490 
   491 * Pure: new 'judgment' command records explicit information about the
   492 object-logic embedding (used by several tools internally); no longer
   493 use hard-wired "Trueprop";
   494 
   495 * Pure: added 'corollary' command;
   496 
   497 * Pure: fixed 'token_translation' command;
   498 
   499 * Pure: removed obsolete 'exported' attribute;
   500 
   501 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   502 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   503 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   504 
   505 * Pure: method 'atomize' presents local goal premises as object-level
   506 statements (atomic meta-level propositions); setup controlled via
   507 rewrite rules declarations of 'atomize' attribute; example
   508 application: 'induct' method with proper rule statements in improper
   509 proof *scripts*;
   510 
   511 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   512 now consider the syntactic context of assumptions, giving a better
   513 chance to get type-inference of the arguments right (this is
   514 especially important for locales);
   515 
   516 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   517 mode;
   518 
   519 * Pure/obtain: the formal conclusion "thesis", being marked as
   520 ``internal'', may no longer be reference directly in the text;
   521 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   522 situations;
   523 
   524 * Pure: generic 'sym' attribute which declares a rule both as pure
   525 'elim?' and for the 'symmetric' operation;
   526 
   527 * Pure: marginal comments ``--'' may now occur just anywhere in the
   528 text; the fixed correlation with particular command syntax has been
   529 discontinued;
   530 
   531 * Pure: new method 'rules' is particularly well-suited for proof
   532 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   533 but often produces more compact proof terms with less detours;
   534 
   535 * Pure/Provers/classical: simplified integration with pure rule
   536 attributes and methods; the classical "intro?/elim?/dest?"
   537 declarations coincide with the pure ones; the "rule" method no longer
   538 includes classically swapped intros; "intro" and "elim" methods no
   539 longer pick rules from the context; also got rid of ML declarations
   540 AddXIs/AddXEs/AddXDs; all of this has some potential for
   541 INCOMPATIBILITY;
   542 
   543 * Provers/classical: attribute 'swapped' produces classical inversions
   544 of introduction rules;
   545 
   546 * Provers/simplifier: 'simplified' attribute may refer to explicit
   547 rules instead of full simplifier context; 'iff' attribute handles
   548 conditional rules;
   549 
   550 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   551 
   552 * HOL: 'recdef' now fails on unfinished automated proofs, use
   553 "(permissive)" option to recover old behavior;
   554 
   555 * HOL: 'inductive' no longer features separate (collective) attributes
   556 for 'intros' (was found too confusing);
   557 
   558 * HOL: properly declared induction rules less_induct and
   559 wf_induct_rule;
   560 
   561 
   562 *** HOL ***
   563 
   564 * HOL: moved over to sane numeral syntax; the new policy is as
   565 follows:
   566 
   567   - 0 and 1 are polymorphic constants, which are defined on any
   568   numeric type (nat, int, real etc.);
   569 
   570   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   571   binary representation internally;
   572 
   573   - type nat has special constructor Suc, and generally prefers Suc 0
   574   over 1::nat and Suc (Suc 0) over 2::nat;
   575 
   576 This change may cause significant problems of INCOMPATIBILITY; here
   577 are some hints on converting existing sources:
   578 
   579   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   580   entities, so expressions involving "-" (unary or binary minus) need
   581   to be spaced properly;
   582 
   583   - existing occurrences of "1" may need to be constraint "1::nat" or
   584   even replaced by Suc 0; similar for old "2";
   585 
   586   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   587 
   588   - remove all special provisions on numerals in proofs;
   589 
   590 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   591 representation (depends on bin_arith_simps in the default context);
   592 
   593 * HOL: symbolic syntax for x^2 (numeral 2);
   594 
   595 * HOL: the class of all HOL types is now called "type" rather than
   596 "term"; INCOMPATIBILITY, need to adapt references to this type class
   597 in axclass/classes, instance/arities, and (usually rare) occurrences
   598 in typings (of consts etc.); internally the class is called
   599 "HOL.type", ML programs should refer to HOLogic.typeS;
   600 
   601 * HOL/record package improvements:
   602   - new derived operations "fields" to build a partial record section,
   603     "extend" to promote a fixed record to a record scheme, and
   604     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   605     declared as simp by default;
   606   - shared operations ("more", "fields", etc.) now need to be always
   607     qualified) --- potential INCOMPATIBILITY;
   608   - removed "make_scheme" operations (use "make" with "extend") --
   609     INCOMPATIBILITY;
   610   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   611   - provides cases/induct rules for use with corresponding Isar
   612     methods (for concrete records, record schemes, concrete more
   613     parts, and schematic more parts -- in that order);
   614   - internal definitions directly based on a light-weight abstract
   615     theory of product types over typedef rather than datatype;
   616 
   617 * HOL: generic code generator for generating executable ML code from
   618 specifications; specific support for HOL constructs such as inductive
   619 datatypes and sets, as well as recursive functions; can be invoked
   620 via 'generate_code' theory section;
   621 
   622 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   623 
   624 * HOL: consolidated and renamed several theories.  In particular:
   625 	Ord.thy has been absorbed into HOL.thy
   626 	String.thy has been absorbed into List.thy
   627  
   628 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   629 (beware of argument permutation!);
   630 
   631 * HOL: linorder_less_split superseded by linorder_cases;
   632 
   633 * HOL/List: "nodups" renamed to "distinct";
   634 
   635 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   636 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   637   - Ex_def has changed, now need to use some_eq_ex
   638 
   639 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   640 in this (rare) case use:
   641 
   642   delSWrapper "split_all_tac"
   643   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   644 
   645 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   646 MAY FAIL;
   647 
   648 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   649 Isabelle's type classes, ^ on functions and relations has too general
   650 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   651 necessary to attach explicit type constraints;
   652 
   653 * HOL/Relation: the prefix name of the infix "O" has been changed from
   654 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   655 renamed accordingly (eg "compI" -> "rel_compI").
   656 
   657 * HOL: syntax translations now work properly with numerals and records
   658 expressions;
   659 
   660 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   661 of "lam" -- INCOMPATIBILITY;
   662 
   663 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   664 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   665 renamed "Product_Type.unit";
   666 
   667 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   668 
   669 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   670 the "cases" method);
   671 
   672 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   673 Florian Kammüller);
   674 
   675 * HOL/IMP: updated and converted to new-style theory format; several
   676 parts turned into readable document, with proper Isar proof texts and
   677 some explanations (by Gerwin Klein);
   678 
   679 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   680 
   681 * HOL-Hyperreal is now a logic image;
   682 
   683 
   684 *** HOLCF ***
   685 
   686 * Isar: consts/constdefs supports mixfix syntax for continuous
   687 operations;
   688 
   689 * Isar: domain package adapted to new-style theory format, e.g. see
   690 HOLCF/ex/Dnat.thy;
   691 
   692 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   693 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   694 lift.induct_tac, always use UU instead of Undef;
   695 
   696 * HOLCF/IMP: updated and converted to new-style theory;
   697 
   698 
   699 *** ZF ***
   700 
   701 * Isar: proper integration of logic-specific tools and packages,
   702 including theory commands '(co)inductive', '(co)datatype',
   703 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   704 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   705 
   706 * theory Main no longer includes AC; for the Axiom of Choice, base
   707 your theory on Main_ZFC;
   708 
   709 * the integer library now covers quotients and remainders, with many
   710 laws relating division to addition, multiplication, etc.;
   711 
   712 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   713 typeless version of the formalism;
   714 
   715 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   716 format;
   717 
   718 * ZF/Induct: new directory for examples of inductive definitions,
   719 including theory Multiset for multiset orderings; converted to
   720 new-style theory format;
   721 
   722 * ZF: many new theorems about lists, ordinals, etc.;
   723 
   724 
   725 *** General ***
   726 
   727 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   728 variable proof controls level of detail: 0 = no proofs (only oracle
   729 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   730 also ref manual for further ML interfaces;
   731 
   732 * Pure/axclass: removed obsolete ML interface
   733 goal_subclass/goal_arity;
   734 
   735 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   736 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   737 separate tokens, so expressions involving minus need to be spaced
   738 properly;
   739 
   740 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   741 rather than "infixl" or "infixr";
   742 
   743 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   744 sort constraint specifications in type inference; e.g. "x::_::foo"
   745 ensures that the type of "x" is of sort "foo" (but not necessarily a
   746 type variable);
   747 
   748 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   749 control output of nested => (types); the default behavior is
   750 "type_brackets";
   751 
   752 * Pure/syntax: builtin parse translation for "_constify" turns valued
   753 tokens into AST constants;
   754 
   755 * Pure/syntax: prefer later declarations of translations and print
   756 translation functions; potential INCOMPATIBILITY: need to reverse
   757 multiple declarations for same syntax element constant;
   758 
   759 * Pure/show_hyps reset by default (in accordance to existing Isar
   760 practice);
   761 
   762 * Provers/classical: renamed addaltern to addafter, addSaltern to
   763 addSafter;
   764 
   765 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   766 as well;
   767 
   768 * system: tested support for MacOS X; should be able to get Isabelle +
   769 Proof General to work in a plain Terminal after installing Poly/ML
   770 (e.g. from the Isabelle distribution area) and GNU bash alone
   771 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   772 support requires further installations, e.g. from
   773 http://fink.sourceforge.net/);
   774 
   775 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   776 
   777 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   778 of 40 MB), cf. ML_OPTIONS;
   779 
   780 * system: Proof General keywords specification is now part of the
   781 Isabelle distribution (see etc/isar-keywords.el);
   782 
   783 * system: support for persistent Proof General sessions (refrain from
   784 outdating all loaded theories on startup); user may create writable
   785 logic images like this: ``isabelle -q HOL Test'';
   786 
   787 * system: smart selection of Isabelle process versus Isabelle
   788 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   789 run both "isabelle" and "Isabelle" even if file names are badly
   790 damaged (executable inspects the case of the first letter of its own
   791 name); added separate "isabelle-process" and "isabelle-interface";
   792 
   793 * system: refrain from any attempt at filtering input streams; no
   794 longer support ``8bit'' encoding of old isabelle font, instead proper
   795 iso-latin characters may now be used; the related isatools
   796 "symbolinput" and "nonascii" have disappeared as well;
   797 
   798 * system: removed old "xterm" interface (the print modes "xterm" and
   799 "xterm_color" are still available for direct use in a suitable
   800 terminal);
   801 
   802 
   803 
   804 New in Isabelle99-2 (February 2001)
   805 -----------------------------------
   806 
   807 *** Overview of INCOMPATIBILITIES ***
   808 
   809 * HOL: please note that theories in the Library and elsewhere often use the
   810 new-style (Isar) format; to refer to their theorems in an ML script you must
   811 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   812 
   813 * HOL: inductive package no longer splits induction rule aggressively,
   814 but only as far as specified by the introductions given; the old
   815 format may be recovered via ML function complete_split_rule or attribute
   816 'split_rule (complete)';
   817 
   818 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   819 gfp_Tarski to gfp_unfold;
   820 
   821 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   822 
   823 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   824 relation); infix "^^" has been renamed "``"; infix "``" has been
   825 renamed "`"; "univalent" has been renamed "single_valued";
   826 
   827 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   828 operation;
   829 
   830 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   831 
   832 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   833 
   834 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   835 consequence, it is no longer monotonic wrt. the local goal context
   836 (which is now passed through the inductive cases);
   837 
   838 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   839 \<gg> to \<ggreater>;
   840 
   841 
   842 *** Document preparation ***
   843 
   844 * \isabellestyle{NAME} selects version of Isabelle output (currently
   845 available: are "it" for near math-mode best-style output, "sl" for
   846 slanted text style, and "tt" for plain type-writer; if no
   847 \isabellestyle command is given, output is according to slanted
   848 type-writer);
   849 
   850 * support sub/super scripts (for single symbols only), input syntax is
   851 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   852 
   853 * some more standard symbols; see Appendix A of the system manual for
   854 the complete list of symbols defined in isabellesym.sty;
   855 
   856 * improved isabelle style files; more abstract symbol implementation
   857 (should now use \isamath{...} and \isatext{...} in custom symbol
   858 definitions);
   859 
   860 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   861 state; Note that presentation of goal states does not conform to
   862 actual human-readable proof documents.  Please do not include goal
   863 states into document output unless you really know what you are doing!
   864 
   865 * proper indentation of antiquoted output with proportional LaTeX
   866 fonts;
   867 
   868 * no_document ML operator temporarily disables LaTeX document
   869 generation;
   870 
   871 * isatool unsymbolize tunes sources for plain ASCII communication;
   872 
   873 
   874 *** Isar ***
   875 
   876 * Pure: Isar now suffers initial goal statements to contain unbound
   877 schematic variables (this does not conform to actual readable proof
   878 documents, due to unpredictable outcome and non-compositional proof
   879 checking); users who know what they are doing may use schematic goals
   880 for Prolog-style synthesis of proven results;
   881 
   882 * Pure: assumption method (an implicit finishing) now handles actual
   883 rules as well;
   884 
   885 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   886 initial goal, declare "that" only as Pure intro (only for single
   887 steps); the "that" rule assumption may now be involved in implicit
   888 finishing, thus ".." becomes a feasible for trivial obtains;
   889 
   890 * Pure: default proof step now includes 'intro_classes'; thus trivial
   891 instance proofs may be performed by "..";
   892 
   893 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   894 statements as well;
   895 
   896 * Pure: more robust selection of calculational rules;
   897 
   898 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   899 rule (as well as the assumption rule);
   900 
   901 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   902 lemmas, using the graph browser tool;
   903 
   904 * Pure: predict failure of "show" in interactive mode;
   905 
   906 * Pure: 'thms_containing' now takes actual terms as arguments;
   907 
   908 * HOL: improved method 'induct' --- now handles non-atomic goals
   909 (potential INCOMPATIBILITY); tuned error handling;
   910 
   911 * HOL: cases and induct rules now provide explicit hints about the
   912 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   913 any remaining facts are inserted into the goal verbatim;
   914 
   915 * HOL: local contexts (aka cases) may now contain term bindings as
   916 well; the 'cases' and 'induct' methods new provide a ?case binding for
   917 the result to be shown in each case;
   918 
   919 * HOL: added 'recdef_tc' command;
   920 
   921 * isatool convert assists in eliminating legacy ML scripts;
   922 
   923 
   924 *** HOL ***
   925 
   926 * HOL/Library: a collection of generic theories to be used together
   927 with main HOL; the theory loader path already includes this directory
   928 by default; the following existing theories have been moved here:
   929 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   930 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   931 
   932 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   933 modelling and verification task performed in Isabelle/HOL +
   934 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   935 
   936 * HOL/Algebra: special summation operator SUM no longer exists, it has
   937 been replaced by setsum; infix 'assoc' now has priority 50 (like
   938 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   939 'domain', this makes the theory consistent with mathematical
   940 literature;
   941 
   942 * HOL basics: added overloaded operations "inverse" and "divide"
   943 (infix "/"), syntax for generic "abs" operation, generic summation
   944 operator \<Sum>;
   945 
   946 * HOL/typedef: simplified package, provide more useful rules (see also
   947 HOL/subset.thy);
   948 
   949 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   950 now expressed as a proper nested rule (old-style tactic scripts may
   951 require atomize_strip_tac to cope with non-atomic premises);
   952 
   953 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   954 to "split_conv" (old name still available for compatibility);
   955 
   956 * HOL: improved concrete syntax for strings (e.g. allows translation
   957 rules with string literals);
   958 
   959 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   960  and Fleuriot's mechanization of analysis, including the transcendental
   961  functions for the reals;
   962 
   963 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   964 
   965 
   966 *** CTT ***
   967 
   968 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   969 "lam" is displayed as TWO lambda-symbols
   970 
   971 * CTT: theory Main now available, containing everything (that is, Bool
   972 and Arith);
   973 
   974 
   975 *** General ***
   976 
   977 * Pure: the Simplifier has been implemented properly as a derived rule
   978 outside of the actual kernel (at last!); the overall performance
   979 penalty in practical applications is about 50%, while reliability of
   980 the Isabelle inference kernel has been greatly improved;
   981 
   982 * print modes "brackets" and "no_brackets" control output of nested =>
   983 (types) and ==> (props); the default behaviour is "brackets";
   984 
   985 * Provers: fast_tac (and friends) now handle actual object-logic rules
   986 as assumptions as well;
   987 
   988 * system: support Poly/ML 4.0;
   989 
   990 * system: isatool install handles KDE version 1 or 2;
   991 
   992 
   993 
   994 New in Isabelle99-1 (October 2000)
   995 ----------------------------------
   996 
   997 *** Overview of INCOMPATIBILITIES ***
   998 
   999 * HOL: simplification of natural numbers is much changed; to partly
  1000 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
  1001 issue the following ML commands:
  1002 
  1003   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
  1004   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
  1005 
  1006 * HOL: simplification no longer dives into case-expressions; this is
  1007 controlled by "t.weak_case_cong" for each datatype t;
  1008 
  1009 * HOL: nat_less_induct renamed to less_induct;
  1010 
  1011 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
  1012 fixsome to patch .thy and .ML sources automatically;
  1013 
  1014   select_equality  -> some_equality
  1015   select_eq_Ex     -> some_eq_ex
  1016   selectI2EX       -> someI2_ex
  1017   selectI2         -> someI2
  1018   selectI          -> someI
  1019   select1_equality -> some1_equality
  1020   Eps_sym_eq       -> some_sym_eq_trivial
  1021   Eps_eq           -> some_eq_trivial
  1022 
  1023 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
  1024 
  1025 * HOL: removed obsolete theorem binding expand_if (refer to split_if
  1026 instead);
  1027 
  1028 * HOL: the recursion equations generated by 'recdef' are now called
  1029 f.simps instead of f.rules;
  1030 
  1031 * HOL: qed_spec_mp now also handles bounded ALL as well;
  1032 
  1033 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  1034 sometimes be needed;
  1035 
  1036 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  1037 
  1038 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  1039 
  1040 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  1041 product is now "<*>" instead of "Times"; the lexicographic product is
  1042 now "<*lex*>" instead of "**";
  1043 
  1044 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  1045 of main HOL, but was unused); better use HOL's datatype package;
  1046 
  1047 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  1048 the old syntax may be recovered as follows:
  1049 
  1050   syntax (symbols)
  1051     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  1052       (infixl "\\<oplus>" 100)
  1053 
  1054 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1055 
  1056 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1057 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1058 internally;
  1059 
  1060 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1061 changed from A/r to A//r;
  1062 
  1063 * ZF: new treatment of arithmetic (nat & int) may break some old
  1064 proofs;
  1065 
  1066 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1067 rulify -> rule_format, elimify -> elim_format, ...);
  1068 
  1069 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1070 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1071 should have to change intro!! to intro? only); replaced "delrule" by
  1072 "rule del";
  1073 
  1074 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1075 
  1076 * Provers: strengthened force_tac by using new first_best_tac;
  1077 
  1078 * LaTeX document preparation: several changes of isabelle.sty (see
  1079 lib/texinputs);
  1080 
  1081 
  1082 *** Document preparation ***
  1083 
  1084 * formal comments (text blocks etc.) in new-style theories may now
  1085 contain antiquotations of thm/prop/term/typ/text to be presented
  1086 according to latex print mode; concrete syntax is like this:
  1087 @{term[show_types] "f(x) = a + x"};
  1088 
  1089 * isatool mkdir provides easy setup of Isabelle session directories,
  1090 including proper document sources;
  1091 
  1092 * generated LaTeX sources are now deleted after successful run
  1093 (isatool document -c); may retain a copy somewhere else via -D option
  1094 of isatool usedir;
  1095 
  1096 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1097 style files, achieving self-contained LaTeX sources and simplifying
  1098 LaTeX debugging;
  1099 
  1100 * old-style theories now produce (crude) LaTeX output as well;
  1101 
  1102 * browser info session directories are now self-contained (may be put
  1103 on WWW server seperately); improved graphs of nested sessions; removed
  1104 graph for 'all sessions';
  1105 
  1106 * several improvements in isabelle style files; \isabellestyle{it}
  1107 produces fake math mode output; \isamarkupheader is now \section by
  1108 default; see lib/texinputs/isabelle.sty etc.;
  1109 
  1110 
  1111 *** Isar ***
  1112 
  1113 * Isar/Pure: local results and corresponding term bindings are now
  1114 subject to Hindley-Milner polymorphism (similar to ML); this
  1115 accommodates incremental type-inference very nicely;
  1116 
  1117 * Isar/Pure: new derived language element 'obtain' supports
  1118 generalized existence reasoning;
  1119 
  1120 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1121 support accumulation of results, without applying any rules yet;
  1122 useful to collect intermediate results without explicit name
  1123 references, and for use with transitivity rules with more than 2
  1124 premises;
  1125 
  1126 * Isar/Pure: scalable support for case-analysis type proofs: new
  1127 'case' language element refers to local contexts symbolically, as
  1128 produced by certain proof methods; internally, case names are attached
  1129 to theorems as "tags";
  1130 
  1131 * Isar/Pure: theory command 'hide' removes declarations from
  1132 class/type/const name spaces;
  1133 
  1134 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1135 indicate potential overloading;
  1136 
  1137 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1138 
  1139 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1140 "{a,b,c}" instead of {a,b,c};
  1141 
  1142 * Isar/Pure now provides its own version of intro/elim/dest
  1143 attributes; useful for building new logics, but beware of confusion
  1144 with the version in Provers/classical;
  1145 
  1146 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1147 case name 'antecedent';
  1148 
  1149 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1150 to the current context is now done automatically);
  1151 
  1152 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1153 for definining proof methods in ML;
  1154 
  1155 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1156 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1157 most cases, one should have to change intro!! to intro? only);
  1158 replaced "delrule" by "rule del";
  1159 
  1160 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1161 'symmetric' attribute (the latter supercedes [RS sym]);
  1162 
  1163 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1164 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1165 well (including splits);
  1166 
  1167 * Isar/Provers: Simplifier and Classical methods now support all kind
  1168 of modifiers used in the past, including 'cong', 'iff', etc.
  1169 
  1170 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1171 of Simplifier and Classical reasoner);
  1172 
  1173 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1174 now support named cases; major packages (inductive, datatype, primrec,
  1175 recdef) support case names and properly name parameters;
  1176 
  1177 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1178 monotonicity conditions are extracted to be proven at end of
  1179 calculations;
  1180 
  1181 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1182 method anyway;
  1183 
  1184 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1185 split_if split_if_asm; datatype package provides theorems foo.splits =
  1186 foo.split foo.split_asm for each datatype;
  1187 
  1188 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1189 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1190 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1191 use "(cases (simplified))" method in proper proof texts);
  1192 
  1193 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1194 
  1195 * Isar: names of theorems etc. may be natural numbers as well;
  1196 
  1197 * Isar: 'pr' command: optional arguments for goals_limit and
  1198 ProofContext.prems_limit; no longer prints theory contexts, but only
  1199 proof states;
  1200 
  1201 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1202 additional print modes to be specified; e.g. "pr(latex)" will print
  1203 proof state according to the Isabelle LaTeX style;
  1204 
  1205 * Isar: improved support for emulating tactic scripts, including proof
  1206 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1207 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1208 (for HOL datatypes);
  1209 
  1210 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1211 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1212 'proof method scripts' have to be in depth-first order;
  1213 
  1214 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1215 
  1216 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1217 should instead use individual commands for printing items
  1218 (print_commands, print_methods etc.);
  1219 
  1220 * Isar: added 'nothing' --- the empty list of theorems;
  1221 
  1222 
  1223 *** HOL ***
  1224 
  1225 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1226 corresponding virtual machine and a specification of its bytecode
  1227 verifier and a lightweight bytecode verifier, including proofs of
  1228 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1229 Cornelia Pusch (see also the homepage of project Bali at
  1230 http://isabelle.in.tum.de/Bali/);
  1231 
  1232 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1233 Clemens Ballarin;
  1234 
  1235 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1236 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1237 Rasmussen;
  1238 
  1239 * HOL/Lattice: fundamental concepts of lattice theory and order
  1240 structures, including duals, properties of bounds versus algebraic
  1241 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1242 Theorem for complete lattices etc.; may also serve as a demonstration
  1243 for abstract algebraic reasoning using axiomatic type classes, and
  1244 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1245 
  1246 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1247 von Oheimb;
  1248 
  1249 * HOL/IMPP: extension of IMP with local variables and mutually
  1250 recursive procedures, by David von Oheimb;
  1251 
  1252 * HOL/Lambda: converted into new-style theory and document;
  1253 
  1254 * HOL/ex/Multiquote: example of multiple nested quotations and
  1255 anti-quotations -- basically a generalized version of de-Bruijn
  1256 representation; very useful in avoiding lifting of operations;
  1257 
  1258 * HOL/record: added general record equality rule to simpset; fixed
  1259 select-update simplification procedure to handle extended records as
  1260 well; admit "r" as field name;
  1261 
  1262 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1263 other numeric types and also as the identity of groups, rings, etc.;
  1264 
  1265 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1266 Types nat and int belong to this axclass;
  1267 
  1268 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1269    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1270    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1271   two terms #m*u and #n*u are replaced by #(m+n)*u
  1272     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1273   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1274     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1275 
  1276 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1277 powerful prover for predicate logic but knows nothing of clasets; see
  1278 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1279 
  1280 * HOL: new version of "case_tac" subsumes both boolean case split and
  1281 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1282 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1283 
  1284 * HOL: simplification no longer dives into case-expressions: only the
  1285 selector expression is simplified, but not the remaining arms; to
  1286 enable full simplification of case-expressions for datatype t, you may
  1287 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1288 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1289 
  1290 * HOL/recdef: the recursion equations generated by 'recdef' for
  1291 function 'f' are now called f.simps instead of f.rules; if all
  1292 termination conditions are proved automatically, these simplification
  1293 rules are added to the simpset, as in primrec; rules may be named
  1294 individually as well, resulting in a separate list of theorems for
  1295 each equation;
  1296 
  1297 * HOL/While is a new theory that provides a while-combinator. It
  1298 permits the definition of tail-recursive functions without the
  1299 provision of a termination measure. The latter is necessary once the
  1300 invariant proof rule for while is applied.
  1301 
  1302 * HOL: new (overloaded) notation for the set of elements below/above
  1303 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1304 
  1305 * HOL: theorems impI, allI, ballI bound as "strip";
  1306 
  1307 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1308 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1309 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1310 
  1311 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1312 
  1313 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1314 main HOL, but was unused);
  1315 
  1316 * HOL: fewer consts declared as global (e.g. have to refer to
  1317 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1318 
  1319 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1320 in case of overlap with user translations (e.g. judgements over
  1321 tuples); (note that the underlying logical represenation is still
  1322 bogus);
  1323 
  1324 
  1325 *** ZF ***
  1326 
  1327 * ZF: simplification automatically cancels common terms in arithmetic
  1328 expressions over nat and int;
  1329 
  1330 * ZF: new treatment of nat to minimize type-checking: all operators
  1331 coerce their operands to a natural number using the function natify,
  1332 making the algebraic laws unconditional;
  1333 
  1334 * ZF: as above, for int: operators coerce their operands to an integer
  1335 using the function intify;
  1336 
  1337 * ZF: the integer library now contains many of the usual laws for the
  1338 orderings, including $<=, and monotonicity laws for $+ and $*;
  1339 
  1340 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1341 simplification;
  1342 
  1343 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1344 to the simplifier and classical reasoner simultaneously;
  1345 
  1346 
  1347 *** General ***
  1348 
  1349 * Provers: blast_tac now handles actual object-logic rules as
  1350 assumptions; note that auto_tac uses blast_tac internally as well;
  1351 
  1352 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1353 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1354 
  1355 * Provers: delrules now handles destruct rules as well (no longer need
  1356 explicit make_elim);
  1357 
  1358 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1359   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1360 use instead the strong form,
  1361   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1362 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1363 from destruct-rules;
  1364 
  1365 * Provers: Simplifier.easy_setup provides a fast path to basic
  1366 Simplifier setup for new object-logics;
  1367 
  1368 * Pure: AST translation rules no longer require constant head on LHS;
  1369 
  1370 * Pure: improved name spaces: ambiguous output is qualified; support
  1371 for hiding of names;
  1372 
  1373 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1374 XSYMBOL_HOME; no longer need to do manual configuration in most
  1375 situations;
  1376 
  1377 * system: compression of ML heaps images may now be controlled via -c
  1378 option of isabelle and isatool usedir (currently only observed by
  1379 Poly/ML);
  1380 
  1381 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1382 useful for remote X11);
  1383 
  1384 * system: provide TAGS file for Isabelle sources;
  1385 
  1386 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1387 order;
  1388 
  1389 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1390 timing flag supersedes proof_timing and Toplevel.trace;
  1391 
  1392 * ML: new combinators |>> and |>>> for incremental transformations
  1393 with secondary results (e.g. certain theory extensions):
  1394 
  1395 * ML: PureThy.add_defs gets additional argument to indicate potential
  1396 overloading (usually false);
  1397 
  1398 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1399 results;
  1400 
  1401 
  1402 
  1403 New in Isabelle99 (October 1999)
  1404 --------------------------------
  1405 
  1406 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1407 
  1408 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1409 are no longer simplified.  (This allows the simplifier to unfold recursive
  1410 functional programs.)  To restore the old behaviour, declare
  1411 
  1412     Delcongs [if_weak_cong];
  1413 
  1414 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1415 complement;
  1416 
  1417 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1418 
  1419 * HOL/datatype: mutual_induct_tac no longer exists --
  1420   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1421 
  1422 * HOL/typedef: fixed type inference for representing set; type
  1423 arguments now have to occur explicitly on the rhs as type constraints;
  1424 
  1425 * ZF: The con_defs part of an inductive definition may no longer refer
  1426 to constants declared in the same theory;
  1427 
  1428 * HOL, ZF: the function mk_cases, generated by the inductive
  1429 definition package, has lost an argument.  To simplify its result, it
  1430 uses the default simpset instead of a supplied list of theorems.
  1431 
  1432 * HOL/List: the constructors of type list are now Nil and Cons;
  1433 
  1434 * Simplifier: the type of the infix ML functions
  1435         setSSolver addSSolver setSolver addSolver
  1436 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1437 for packaging solvers. A solver is created via
  1438         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1439 where the string argument is only a comment.
  1440 
  1441 
  1442 *** Proof tools ***
  1443 
  1444 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1445 decision procedure for linear arithmetic. Currently it is used for
  1446 types `nat', `int', and `real' in HOL (see below); it can, should and
  1447 will be instantiated for other types and logics as well.
  1448 
  1449 * The simplifier now accepts rewrite rules with flexible heads, eg
  1450      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1451   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1452   matching.
  1453 
  1454 
  1455 *** General ***
  1456 
  1457 * New Isabelle/Isar subsystem provides an alternative to traditional
  1458 tactical theorem proving; together with the ProofGeneral/isar user
  1459 interface it offers an interactive environment for developing human
  1460 readable proof documents (Isar == Intelligible semi-automated
  1461 reasoning); for further information see isatool doc isar-ref,
  1462 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1463 
  1464 * improved and simplified presentation of theories: better HTML markup
  1465 (including colors), graph views in several sizes; isatool usedir now
  1466 provides a proper interface for user theories (via -P option); actual
  1467 document preparation based on (PDF)LaTeX is available as well (for
  1468 new-style theories only); see isatool doc system for more information;
  1469 
  1470 * native support for Proof General, both for classic Isabelle and
  1471 Isabelle/Isar;
  1472 
  1473 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1474 using the graph browser tool;
  1475 
  1476 * Isabelle manuals now also available as PDF;
  1477 
  1478 * theory loader rewritten from scratch (may not be fully
  1479 bug-compatible); old loadpath variable has been replaced by show_path,
  1480 add_path, del_path, reset_path functions; new operations such as
  1481 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1482 isatool doc ref);
  1483 
  1484 * improved isatool install: option -k creates KDE application icon,
  1485 option -p DIR installs standalone binaries;
  1486 
  1487 * added ML_PLATFORM setting (useful for cross-platform installations);
  1488 more robust handling of platform specific ML images for SML/NJ;
  1489 
  1490 * the settings environment is now statically scoped, i.e. it is never
  1491 created again in sub-processes invoked from isabelle, isatool, or
  1492 Isabelle;
  1493 
  1494 * path element specification '~~' refers to '$ISABELLE_HOME';
  1495 
  1496 * in locales, the "assumes" and "defines" parts may be omitted if
  1497 empty;
  1498 
  1499 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1500 long arrows);
  1501 
  1502 * new print_mode "HTML";
  1503 
  1504 * new flag show_tags controls display of tags of theorems (which are
  1505 basically just comments that may be attached by some tools);
  1506 
  1507 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1508 mode and goal output format:
  1509 
  1510 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1511 244c244
  1512 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1513 ---
  1514 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1515 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1516 181c181
  1517 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1518 ---
  1519 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1520 
  1521 * function bind_thms stores lists of theorems (cf. bind_thm);
  1522 
  1523 * new shorthand tactics ftac, eatac, datac, fatac;
  1524 
  1525 * qed (and friends) now accept "" as result name; in that case the
  1526 theorem is not stored, but proper checks and presentation of the
  1527 result still apply;
  1528 
  1529 * theorem database now also indexes constants "Trueprop", "all",
  1530 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1531 
  1532 
  1533 *** HOL ***
  1534 
  1535 ** HOL arithmetic **
  1536 
  1537 * There are now decision procedures for linear arithmetic over nat and
  1538 int:
  1539 
  1540 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1541 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1542 are treated as atomic; subformulae not involving type `nat' or `int'
  1543 are ignored; quantified subformulae are ignored unless they are
  1544 positive universal or negative existential. The tactic has to be
  1545 invoked by hand and can be a little bit slow. In particular, the
  1546 running time is exponential in the number of occurrences of `min' and
  1547 `max', and `-' on `nat'.
  1548 
  1549 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1550 (negated) (in)equalities among the premises and the conclusion into
  1551 account (i.e. no compound formulae) and does not know about `min' and
  1552 `max', and `-' on `nat'. It is fast and is used automatically by the
  1553 simplifier.
  1554 
  1555 NB: At the moment, these decision procedures do not cope with mixed
  1556 nat/int formulae where the two parts interact, such as `m < n ==>
  1557 int(m) < int(n)'.
  1558 
  1559 * HOL/Numeral provides a generic theory of numerals (encoded
  1560 efficiently as bit strings); setup for types nat/int/real is in place;
  1561 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1562 int, existing theories and proof scripts may require a few additional
  1563 type constraints;
  1564 
  1565 * integer division and remainder can now be performed on constant
  1566 arguments;
  1567 
  1568 * many properties of integer multiplication, division and remainder
  1569 are now available;
  1570 
  1571 * An interface to the Stanford Validity Checker (SVC) is available through the
  1572 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1573 are proved automatically.  SVC must be installed separately, and its results
  1574 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1575 invocation of the underlying oracle).  For SVC see
  1576   http://verify.stanford.edu/SVC
  1577 
  1578 * IsaMakefile: the HOL-Real target now builds an actual image;
  1579 
  1580 
  1581 ** HOL misc **
  1582 
  1583 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1584 (in Isabelle/Isar) -- by Gertrud Bauer;
  1585 
  1586 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1587 analysis for assembly languages with subtypes;
  1588 
  1589 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1590 -- avoids syntactic ambiguities and treats state, transition, and
  1591 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1592 changed syntax and (many) tactics;
  1593 
  1594 * HOL/inductive: Now also handles more general introduction rules such
  1595   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1596   theorems are now maintained within the theory (maintained via the
  1597   "mono" attribute);
  1598 
  1599 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1600   (using function types) such as
  1601 
  1602   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1603 
  1604 * HOL/record: record_simproc (part of the default simpset) takes care
  1605 of selectors applied to updated records; record_split_tac is no longer
  1606 part of the default claset; update_defs may now be removed from the
  1607 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1608 
  1609   claset_ref () := claset() addSWrapper record_split_wrapper;
  1610   Delsimprocs [record_simproc]
  1611 
  1612 * HOL/typedef: fixed type inference for representing set; type
  1613 arguments now have to occur explicitly on the rhs as type constraints;
  1614 
  1615 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1616 names rather than an ML expression;
  1617 
  1618 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1619 supplied later.  Program schemes can be defined, such as
  1620     "While B C s = (if B s then While B C (C s) else s)"
  1621 where the well-founded relation can be chosen after B and C have been given.
  1622 
  1623 * HOL/List: the constructors of type list are now Nil and Cons;
  1624 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1625 course, ML tools referring to List.list.op # etc. have to be adapted;
  1626 
  1627 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1628 disabled by default; run isabelle with option -m HOL to get back to
  1629 the original Gordon/HOL-style output;
  1630 
  1631 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1632 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1633 
  1634 * HOL basic syntax simplified (more orthogonal): all variants of
  1635 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1636 Eps operator is provided as well: "SOME x. P[x]";
  1637 
  1638 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1639 
  1640 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1641 thus available for user theories;
  1642 
  1643 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1644 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1645 time;
  1646 
  1647 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1648 several times and then mp;
  1649 
  1650 
  1651 *** LK ***
  1652 
  1653 * the notation <<...>> is now available as a notation for sequences of
  1654 formulas;
  1655 
  1656 * the simplifier is now installed
  1657 
  1658 * the axiom system has been generalized (thanks to Soren Heilmann)
  1659 
  1660 * the classical reasoner now has a default rule database
  1661 
  1662 
  1663 *** ZF ***
  1664 
  1665 * new primrec section allows primitive recursive functions to be given
  1666 directly (as in HOL) over datatypes and the natural numbers;
  1667 
  1668 * new tactics induct_tac and exhaust_tac for induction (or case
  1669 analysis) over datatypes and the natural numbers;
  1670 
  1671 * the datatype declaration of type T now defines the recursor T_rec;
  1672 
  1673 * simplification automatically does freeness reasoning for datatype
  1674 constructors;
  1675 
  1676 * automatic type-inference, with AddTCs command to insert new
  1677 type-checking rules;
  1678 
  1679 * datatype introduction rules are now added as Safe Introduction rules
  1680 to the claset;
  1681 
  1682 * the syntax "if P then x else y" is now available in addition to
  1683 if(P,x,y);
  1684 
  1685 
  1686 *** Internal programming interfaces ***
  1687 
  1688 * tuned simplifier trace output; new flag debug_simp;
  1689 
  1690 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1691 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1692 
  1693 * AxClass.axclass_tac lost the theory argument;
  1694 
  1695 * tuned current_goals_markers semantics: begin / end goal avoids
  1696 printing empty lines;
  1697 
  1698 * removed prs and prs_fn hook, which was broken because it did not
  1699 include \n in its semantics, forcing writeln to add one
  1700 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1701 string -> unit if you really want to output text without newline;
  1702 
  1703 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1704 plain output, interface builders may have to enable 'isabelle_font'
  1705 mode to get Isabelle font glyphs as before;
  1706 
  1707 * refined token_translation interface; INCOMPATIBILITY: output length
  1708 now of type real instead of int;
  1709 
  1710 * theory loader actions may be traced via new ThyInfo.add_hook
  1711 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1712 your own database of information attached to *whole* theories -- as
  1713 opposed to intra-theory data slots offered via TheoryDataFun;
  1714 
  1715 * proper handling of dangling sort hypotheses (at last!);
  1716 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1717 extra sort hypotheses that can be witnessed from the type signature;
  1718 the force_strip_shyps flag is gone, any remaining shyps are simply
  1719 left in the theorem (with a warning issued by strip_shyps_warning);
  1720 
  1721 
  1722 
  1723 New in Isabelle98-1 (October 1998)
  1724 ----------------------------------
  1725 
  1726 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1727 
  1728 * several changes of automated proof tools;
  1729 
  1730 * HOL: major changes to the inductive and datatype packages, including
  1731 some minor incompatibilities of theory syntax;
  1732 
  1733 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1734 called `inj_on';
  1735 
  1736 * HOL: removed duplicate thms in Arith:
  1737   less_imp_add_less  should be replaced by  trans_less_add1
  1738   le_imp_add_le      should be replaced by  trans_le_add1
  1739 
  1740 * HOL: unary minus is now overloaded (new type constraints may be
  1741 required);
  1742 
  1743 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1744 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1745 now taken as an integer constant.
  1746 
  1747 * Pure: ML function 'theory_of' renamed to 'theory';
  1748 
  1749 
  1750 *** Proof tools ***
  1751 
  1752 * Simplifier:
  1753   1. Asm_full_simp_tac is now more aggressive.
  1754      1. It will sometimes reorient premises if that increases their power to
  1755         simplify.
  1756      2. It does no longer proceed strictly from left to right but may also
  1757         rotate premises to achieve further simplification.
  1758      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1759      old Asm_full_simp_tac in that it does not rotate premises.
  1760   2. The simplifier now knows a little bit about nat-arithmetic.
  1761 
  1762 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1763 allows for selected deletion of wrappers, by introduction of names for
  1764 wrapper functionals.  This implies that addbefore, addSbefore,
  1765 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1766 and that adding two tactics with the same name overwrites the first
  1767 one (emitting a warning).
  1768   type wrapper = (int -> tactic) -> (int -> tactic)
  1769   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1770   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1771   delWrapper, delSWrapper: claset *  string            -> claset
  1772   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1773 
  1774 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1775 semantics; addbefore now affects only the unsafe part of step_tac
  1776 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1777 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1778 by Force_tac;
  1779 
  1780 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1781 compWrapper; added safe wrapper (and access functions for it);
  1782 
  1783 * HOL/split_all_tac is now much faster and fails if there is nothing
  1784 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1785 and the names of the automatically generated variables have changed.
  1786 split_all_tac has moved within claset() from unsafe wrappers to safe
  1787 wrappers, which means that !!-bound variables are split much more
  1788 aggressively, and safe_tac and clarify_tac now split such variables.
  1789 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1790 Note: the same holds for record_split_tac, which does the job of
  1791 split_all_tac for record fields.
  1792 
  1793 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1794 permanently to the default simpset using Addsplits just like
  1795 Addsimps. They can be removed via Delsplits just like
  1796 Delsimps. Lower-case versions are also available.
  1797 
  1798 * HOL/Simplifier: The rule split_if is now part of the default
  1799 simpset. This means that the simplifier will eliminate all occurrences
  1800 of if-then-else in the conclusion of a goal. To prevent this, you can
  1801 either remove split_if completely from the default simpset by
  1802 `Delsplits [split_if]' or remove it in a specific call of the
  1803 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1804 other case splitting rules to/from the default simpset: every datatype
  1805 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1806 t is the name of the datatype).
  1807 
  1808 * Classical reasoner / Simplifier combination: new force_tac (and
  1809 derivatives Force_tac, force) combines rewriting and classical
  1810 reasoning (and whatever other tools) similarly to auto_tac, but is
  1811 aimed to solve the given subgoal completely.
  1812 
  1813 
  1814 *** General ***
  1815 
  1816 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1817 and `goalw': the theory is no longer needed as an explicit argument -
  1818 the current theory context is used; assumptions are no longer returned
  1819 at the ML-level unless one of them starts with ==> or !!; it is
  1820 recommended to convert to these new commands using isatool fixgoal
  1821 (backup your sources first!);
  1822 
  1823 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1824 the current theory context, and 'theory' to lookup stored theories;
  1825 
  1826 * new theory section 'locale' for declaring constants, assumptions and
  1827 definitions that have local scope;
  1828 
  1829 * new theory section 'nonterminals' for purely syntactic types;
  1830 
  1831 * new theory section 'setup' for generic ML setup functions
  1832 (e.g. package initialization);
  1833 
  1834 * the distribution now includes Isabelle icons: see
  1835 lib/logo/isabelle-{small,tiny}.xpm;
  1836 
  1837 * isatool install - install binaries with absolute references to
  1838 ISABELLE_HOME/bin;
  1839 
  1840 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1841 
  1842 * print mode 'emacs' reserved for Isamode;
  1843 
  1844 * support multiple print (ast) translations per constant name;
  1845 
  1846 * theorems involving oracles are now printed with a suffixed [!];
  1847 
  1848 
  1849 *** HOL ***
  1850 
  1851 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1852 
  1853 * HOL/inductive package reorganized and improved: now supports mutual
  1854 definitions such as
  1855 
  1856   inductive EVEN ODD
  1857     intrs
  1858       null "0 : EVEN"
  1859       oddI "n : EVEN ==> Suc n : ODD"
  1860       evenI "n : ODD ==> Suc n : EVEN"
  1861 
  1862 new theorem list "elims" contains an elimination rule for each of the
  1863 recursive sets; inductive definitions now handle disjunctive premises
  1864 correctly (also ZF);
  1865 
  1866 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1867 "mutual_induct" no longer exists - the induction rule is always
  1868 contained in "induct";
  1869 
  1870 
  1871 * HOL/datatype package re-implemented and greatly improved: now
  1872 supports mutually recursive datatypes such as
  1873 
  1874   datatype
  1875     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1876             | SUM ('a aexp) ('a aexp)
  1877             | DIFF ('a aexp) ('a aexp)
  1878             | NUM 'a
  1879   and
  1880     'a bexp = LESS ('a aexp) ('a aexp)
  1881             | AND ('a bexp) ('a bexp)
  1882             | OR ('a bexp) ('a bexp)
  1883 
  1884 as well as indirectly recursive datatypes such as
  1885 
  1886   datatype
  1887     ('a, 'b) term = Var 'a
  1888                   | App 'b ((('a, 'b) term) list)
  1889 
  1890 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1891 induction on mutually / indirectly recursive datatypes.
  1892 
  1893 Primrec equations are now stored in theory and can be accessed via
  1894 <function_name>.simps.
  1895 
  1896 INCOMPATIBILITIES:
  1897 
  1898   - Theories using datatypes must now have theory Datatype as an
  1899     ancestor.
  1900   - The specific <typename>.induct_tac no longer exists - use the
  1901     generic induct_tac instead.
  1902   - natE has been renamed to nat.exhaust - use exhaust_tac
  1903     instead of res_inst_tac ... natE. Note that the variable
  1904     names in nat.exhaust differ from the names in natE, this
  1905     may cause some "fragile" proofs to fail.
  1906   - The theorems split_<typename>_case and split_<typename>_case_asm
  1907     have been renamed to <typename>.split and <typename>.split_asm.
  1908   - Since default sorts of type variables are now handled correctly,
  1909     some datatype definitions may have to be annotated with explicit
  1910     sort constraints.
  1911   - Primrec definitions no longer require function name and type
  1912     of recursive argument.
  1913 
  1914 Consider using isatool fixdatatype to adapt your theories and proof
  1915 scripts to the new package (backup your sources first!).
  1916 
  1917 
  1918 * HOL/record package: considerably improved implementation; now
  1919 includes concrete syntax for record types, terms, updates; theorems
  1920 for surjective pairing and splitting !!-bound record variables; proof
  1921 support is as follows:
  1922 
  1923   1) standard conversions (selectors or updates applied to record
  1924 constructor terms) are part of the standard simpset;
  1925 
  1926   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1927 made part of standard simpset and claset via addIffs;
  1928 
  1929   3) a tactic for record field splitting (record_split_tac) is part of
  1930 the standard claset (addSWrapper);
  1931 
  1932 To get a better idea about these rules you may retrieve them via
  1933 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1934 the name of your record type.
  1935 
  1936 The split tactic 3) conceptually simplifies by the following rule:
  1937 
  1938   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1939 
  1940 Thus any record variable that is bound by meta-all will automatically
  1941 blow up into some record constructor term, consequently the
  1942 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1943 solve record problems automatically.
  1944 
  1945 
  1946 * reorganized the main HOL image: HOL/Integ and String loaded by
  1947 default; theory Main includes everything;
  1948 
  1949 * automatic simplification of integer sums and comparisons, using cancellation;
  1950 
  1951 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1952 
  1953 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1954 
  1955 * many new identities for unions, intersections, set difference, etc.;
  1956 
  1957 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1958 called split_if, split_split, split_sum_case and split_nat_case (to go
  1959 with add/delsplits);
  1960 
  1961 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1962 (?x::unit) = (); this is made part of the default simpset, which COULD
  1963 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1964 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1965 unit_abs_eta_conv is added in order to counter the effect of
  1966 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1967 %u.f();
  1968 
  1969 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1970 makes more sense);
  1971 
  1972 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1973   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1974   disjointness reasoning but breaking a few old proofs.
  1975 
  1976 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1977 to 'converse' from 'inverse' (for compatibility with ZF and some
  1978 literature);
  1979 
  1980 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1981 the well-founded relation;
  1982 
  1983 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1984     Compl A.  The "Compl" syntax remains available as input syntax for this
  1985     release ONLY.
  1986 
  1987 * HOL/Update: new theory of function updates:
  1988     f(a:=b) == %x. if x=a then b else f x
  1989 may also be iterated as in f(a:=b,c:=d,...);
  1990 
  1991 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1992 
  1993 * HOL/List:
  1994   - new function list_update written xs[i:=v] that updates the i-th
  1995     list position. May also be iterated as in xs[i:=a,j:=b,...].
  1996   - new function `upt' written [i..j(] which generates the list
  1997     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  1998     bound write [i..j], which is a shorthand for [i..j+1(].
  1999   - new lexicographic orderings and corresponding wellfoundedness theorems.
  2000 
  2001 * HOL/Arith:
  2002   - removed 'pred' (predecessor) function;
  2003   - generalized some theorems about n-1;
  2004   - many new laws about "div" and "mod";
  2005   - new laws about greatest common divisors (see theory ex/Primes);
  2006 
  2007 * HOL/Relation: renamed the relational operator r^-1 "converse"
  2008 instead of "inverse";
  2009 
  2010 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  2011   of the multiset ordering;
  2012 
  2013 * directory HOL/Real: a construction of the reals using Dedekind cuts
  2014   (not included by default);
  2015 
  2016 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  2017 
  2018 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  2019   programs, i.e. different program variables may have different types.
  2020 
  2021 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2022   [previously, this check worked only if the rewrite rule was unconditional]
  2023   Now rew can involve either definitions or equalities (either == or =).
  2024 
  2025 
  2026 *** ZF ***
  2027 
  2028 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  2029   only the theorems proved on ZF.ML;
  2030 
  2031 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2032   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2033   disjointness reasoning but breaking a few old proofs.
  2034 
  2035 * ZF/Update: new theory of function updates
  2036     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  2037   may also be iterated as in f(a:=b,c:=d,...);
  2038 
  2039 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  2040 
  2041 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2042   [previously, this check worked only if the rewrite rule was unconditional]
  2043   Now rew can involve either definitions or equalities (either == or =).
  2044 
  2045 * case_tac provided for compatibility with HOL
  2046     (like the old excluded_middle_tac, but with subgoals swapped)
  2047 
  2048 
  2049 *** Internal programming interfaces ***
  2050 
  2051 * Pure: several new basic modules made available for general use, see
  2052 also src/Pure/README;
  2053 
  2054 * improved the theory data mechanism to support encapsulation (data
  2055 kind name replaced by private Object.kind, acting as authorization
  2056 key); new type-safe user interface via functor TheoryDataFun; generic
  2057 print_data function becomes basically useless;
  2058 
  2059 * removed global_names compatibility flag -- all theory declarations
  2060 are qualified by default;
  2061 
  2062 * module Pure/Syntax now offers quote / antiquote translation
  2063 functions (useful for Hoare logic etc. with implicit dependencies);
  2064 see HOL/ex/Antiquote for an example use;
  2065 
  2066 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2067 cterm -> thm;
  2068 
  2069 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2070 subgoal;
  2071 
  2072 * Display.print_goals function moved to Locale.print_goals;
  2073 
  2074 * standard print function for goals supports current_goals_markers
  2075 variable for marking begin of proof, end of proof, start of goal; the
  2076 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2077 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2078 for example;
  2079 
  2080 
  2081 
  2082 New in Isabelle98 (January 1998)
  2083 --------------------------------
  2084 
  2085 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2086 
  2087 * changed lexical syntax of terms / types: dots made part of long
  2088 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2089 
  2090 * simpset (and claset) reference variable replaced by functions
  2091 simpset / simpset_ref;
  2092 
  2093 * no longer supports theory aliases (via merge) and non-trivial
  2094 implicit merge of thms' signatures;
  2095 
  2096 * most internal names of constants changed due to qualified names;
  2097 
  2098 * changed Pure/Sequence interface (see Pure/seq.ML);
  2099 
  2100 
  2101 *** General Changes ***
  2102 
  2103 * hierachically structured name spaces (for consts, types, axms, thms
  2104 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2105 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2106 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2107 long_names for fully qualified output names; NOTE: ML programs
  2108 (special tactics, packages etc.) referring to internal names may have
  2109 to be adapted to cope with fully qualified names; in case of severe
  2110 backward campatibility problems try setting 'global_names' at compile
  2111 time to have enrything declared within a flat name space; one may also
  2112 fine tune name declarations in theories via the 'global' and 'local'
  2113 section;
  2114 
  2115 * reimplemented the implicit simpset and claset using the new anytype
  2116 data filed in signatures; references simpset:simpset ref etc. are
  2117 replaced by functions simpset:unit->simpset and
  2118 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2119 to patch your ML files accordingly;
  2120 
  2121 * HTML output now includes theory graph data for display with Java
  2122 applet or isatool browser; data generated automatically via isatool
  2123 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2124 
  2125 * defs may now be conditional; improved rewrite_goals_tac to handle
  2126 conditional equations;
  2127 
  2128 * defs now admits additional type arguments, using TYPE('a) syntax;
  2129 
  2130 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2131 creates a new theory node; implicit merge of thms' signatures is
  2132 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2133 transfer:theory->thm->thm in (rare) cases;
  2134 
  2135 * improved handling of draft signatures / theories; draft thms (and
  2136 ctyps, cterms) are automatically promoted to real ones;
  2137 
  2138 * slightly changed interfaces for oracles: admit many per theory, named
  2139 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2140 
  2141 * print_goals: optional output of const types (set show_consts and
  2142 show_types);
  2143 
  2144 * improved output of warnings (###) and errors (***);
  2145 
  2146 * subgoal_tac displays a warning if the new subgoal has type variables;
  2147 
  2148 * removed old README and Makefiles;
  2149 
  2150 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2151 
  2152 * removed obsolete init_pps and init_database;
  2153 
  2154 * deleted the obsolete tactical STATE, which was declared by
  2155     fun STATE tacfun st = tacfun st st;
  2156 
  2157 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2158 (which abbreviates $HOME);
  2159 
  2160 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2161 use isatool fixseq to adapt your ML programs (this works for fully
  2162 qualified references to the Sequence structure only!);
  2163 
  2164 * use_thy no longer requires writable current directory; it always
  2165 reloads .ML *and* .thy file, if either one is out of date;
  2166 
  2167 
  2168 *** Classical Reasoner ***
  2169 
  2170 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2171 tactics that use classical reasoning to simplify a subgoal without
  2172 splitting it into several subgoals;
  2173 
  2174 * Safe_tac: like safe_tac but uses the default claset;
  2175 
  2176 
  2177 *** Simplifier ***
  2178 
  2179 * added simplification meta rules:
  2180     (asm_)(full_)simplify: simpset -> thm -> thm;
  2181 
  2182 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2183 logics (again);
  2184 
  2185 * added prems argument to simplification procedures;
  2186 
  2187 * HOL, FOL, ZF: added infix function `addsplits':
  2188   instead of `<simpset> setloop (split_tac <thms>)'
  2189   you can simply write `<simpset> addsplits <thms>'
  2190 
  2191 
  2192 *** Syntax ***
  2193 
  2194 * TYPE('a) syntax for type reflection terms;
  2195 
  2196 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2197 
  2198 * pretty printer: changed order of mixfix annotation preference (again!);
  2199 
  2200 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2201 
  2202 
  2203 *** HOL ***
  2204 
  2205 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2206   with `addloop' of the simplifier to faciliate case splitting in premises.
  2207 
  2208 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2209 
  2210 * HOL/Auth: new protocol proofs including some for the Internet
  2211   protocol TLS;
  2212 
  2213 * HOL/Map: new theory of `maps' a la VDM;
  2214 
  2215 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2216 cancelling out common nat summands from =, <, <= (in)equalities, or
  2217 differences; simplification procedures nat_cancel_factor for
  2218 cancelling common factor from =, <, <= (in)equalities over natural
  2219 sums; nat_cancel contains both kinds of procedures, it is installed by
  2220 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2221 
  2222 * HOL/simplifier: terms of the form
  2223   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2224   are rewritten to
  2225   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2226   and those of the form
  2227   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2228   are rewritten to
  2229   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2230 
  2231 * HOL/datatype
  2232   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2233 
  2234   P(t_case f1 ... fn x) =
  2235      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2236         ...
  2237        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2238      )
  2239 
  2240   and a theorem `split_t_case_asm' of the form
  2241 
  2242   P(t_case f1 ... fn x) =
  2243     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2244         ...
  2245        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2246      )
  2247   which can be added to a simpset via `addsplits'. The existing theorems
  2248   expand_list_case and expand_option_case have been renamed to
  2249   split_list_case and split_option_case.
  2250 
  2251 * HOL/Arithmetic:
  2252   - `pred n' is automatically converted to `n-1'.
  2253     Users are strongly encouraged not to use `pred' any longer,
  2254     because it will disappear altogether at some point.
  2255   - Users are strongly encouraged to write "0 < n" rather than
  2256     "n ~= 0". Theorems and proof tools have been modified towards this
  2257     `standard'.
  2258 
  2259 * HOL/Lists:
  2260   the function "set_of_list" has been renamed "set" (and its theorems too);
  2261   the function "nth" now takes its arguments in the reverse order and
  2262   has acquired the infix notation "!" as in "xs!n".
  2263 
  2264 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2265 
  2266 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2267   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2268 
  2269 * HOL/record: extensible records with schematic structural subtyping
  2270 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2271 still lacks various theorems and concrete record syntax;
  2272 
  2273 
  2274 *** HOLCF ***
  2275 
  2276 * removed "axioms" and "generated by" sections;
  2277 
  2278 * replaced "ops" section by extended "consts" section, which is capable of
  2279   handling the continuous function space "->" directly;
  2280 
  2281 * domain package:
  2282   . proves theorems immediately and stores them in the theory,
  2283   . creates hierachical name space,
  2284   . now uses normal mixfix annotations (instead of cinfix...),
  2285   . minor changes to some names and values (for consistency),
  2286   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2287   . separator between mutual domain defs: changed "," to "and",
  2288   . improved handling of sort constraints;  now they have to
  2289     appear on the left-hand side of the equations only;
  2290 
  2291 * fixed LAM <x,y,zs>.b syntax;
  2292 
  2293 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2294 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2295 
  2296 
  2297 *** FOL and ZF ***
  2298 
  2299 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2300   with `addloop' of the simplifier to faciliate case splitting in premises.
  2301 
  2302 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2303 in HOL, they strip ALL and --> from proved theorems;
  2304 
  2305 
  2306 
  2307 New in Isabelle94-8 (May 1997)
  2308 ------------------------------
  2309 
  2310 *** General Changes ***
  2311 
  2312 * new utilities to build / run / maintain Isabelle etc. (in parts
  2313 still somewhat experimental); old Makefiles etc. still functional;
  2314 
  2315 * new 'Isabelle System Manual';
  2316 
  2317 * INSTALL text, together with ./configure and ./build scripts;
  2318 
  2319 * reimplemented type inference for greater efficiency, better error
  2320 messages and clean internal interface;
  2321 
  2322 * prlim command for dealing with lots of subgoals (an easier way of
  2323 setting goals_limit);
  2324 
  2325 
  2326 *** Syntax ***
  2327 
  2328 * supports alternative (named) syntax tables (parser and pretty
  2329 printer); internal interface is provided by add_modesyntax(_i);
  2330 
  2331 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2332 be used in conjunction with the Isabelle symbol font; uses the
  2333 "symbols" syntax table;
  2334 
  2335 * added token_translation interface (may translate name tokens in
  2336 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2337 the current print_mode); IMPORTANT: user print translation functions
  2338 are responsible for marking newly introduced bounds
  2339 (Syntax.mark_boundT);
  2340 
  2341 * token translations for modes "xterm" and "xterm_color" that display
  2342 names in bold, underline etc. or colors (which requires a color
  2343 version of xterm);
  2344 
  2345 * infixes may now be declared with names independent of their syntax;
  2346 
  2347 * added typed_print_translation (like print_translation, but may
  2348 access type of constant);
  2349 
  2350 
  2351 *** Classical Reasoner ***
  2352 
  2353 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2354 some limitations.  Blast_tac...
  2355   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2356   + ignores elimination rules that don't have the correct format
  2357         (the conclusion MUST be a formula variable)
  2358   + ignores types, which can make HOL proofs fail
  2359   + rules must not require higher-order unification, e.g. apply_type in ZF
  2360     [message "Function Var's argument not a bound variable" relates to this]
  2361   + its proof strategy is more general but can actually be slower
  2362 
  2363 * substitution with equality assumptions no longer permutes other
  2364 assumptions;
  2365 
  2366 * minor changes in semantics of addafter (now called addaltern); renamed
  2367 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2368 (and access functions for it);
  2369 
  2370 * improved combination of classical reasoner and simplifier:
  2371   + functions for handling clasimpsets
  2372   + improvement of addss: now the simplifier is called _after_ the
  2373     safe steps.
  2374   + safe variant of addss called addSss: uses safe simplifications
  2375     _during_ the safe steps. It is more complete as it allows multiple
  2376     instantiations of unknowns (e.g. with slow_tac).
  2377 
  2378 *** Simplifier ***
  2379 
  2380 * added interface for simplification procedures (functions that
  2381 produce *proven* rewrite rules on the fly, depending on current
  2382 redex);
  2383 
  2384 * ordering on terms as parameter (used for ordered rewriting);
  2385 
  2386 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2387 
  2388 * the solver is now split into a safe and an unsafe part.
  2389 This should be invisible for the normal user, except that the
  2390 functions setsolver and addsolver have been renamed to setSolver and
  2391 addSolver; added safe_asm_full_simp_tac;
  2392 
  2393 
  2394 *** HOL ***
  2395 
  2396 * a generic induction tactic `induct_tac' which works for all datatypes and
  2397 also for type `nat';
  2398 
  2399 * a generic case distinction tactic `exhaust_tac' which works for all
  2400 datatypes and also for type `nat';
  2401 
  2402 * each datatype comes with a function `size';
  2403 
  2404 * patterns in case expressions allow tuple patterns as arguments to
  2405 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2406 
  2407 * primrec now also works with type nat;
  2408 
  2409 * recdef: a new declaration form, allows general recursive functions to be
  2410 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2411 
  2412 * the constant for negation has been renamed from "not" to "Not" to
  2413 harmonize with FOL, ZF, LK, etc.;
  2414 
  2415 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2416 infinite lists;
  2417 
  2418 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2419 
  2420 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2421 problems in commutative rings, using axiomatic type classes for + and *;
  2422 
  2423 * more examples in HOL/MiniML and HOL/Auth;
  2424 
  2425 * more default rewrite rules for quantifiers, union/intersection;
  2426 
  2427 * a new constant `arbitrary == @x.False';
  2428 
  2429 * HOLCF/IOA replaces old HOL/IOA;
  2430 
  2431 * HOLCF changes: derived all rules and arities
  2432   + axiomatic type classes instead of classes
  2433   + typedef instead of faking type definitions
  2434   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2435   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2436   + eliminated the types void, one, tr
  2437   + use unit lift and bool lift (with translations) instead of one and tr
  2438   + eliminated blift from Lift3.thy (use Def instead of blift)
  2439   all eliminated rules are derived as theorems --> no visible changes ;
  2440 
  2441 
  2442 *** ZF ***
  2443 
  2444 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2445 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2446 as ZF_cs addSIs [equalityI];
  2447 
  2448 
  2449 
  2450 New in Isabelle94-7 (November 96)
  2451 ---------------------------------
  2452 
  2453 * allowing negative levels (as offsets) in prlev and choplev;
  2454 
  2455 * super-linear speedup for large simplifications;
  2456 
  2457 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2458 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2459 FAIL); can suppress it using the command Delsimps (ex_simps @
  2460 all_simps); De Morgan laws are also now included, by default;
  2461 
  2462 * improved printing of ==>  :  ~:
  2463 
  2464 * new object-logic "Sequents" adds linear logic, while replacing LK
  2465 and Modal (thanks to Sara Kalvala);
  2466 
  2467 * HOL/Auth: correctness proofs for authentication protocols;
  2468 
  2469 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2470 examples on HOL/Auth);
  2471 
  2472 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2473 the rewriter and classical reasoner simultaneously;
  2474 
  2475 * function uresult no longer returns theorems in "standard" format;
  2476 regain previous version by: val uresult = standard o uresult;
  2477 
  2478 
  2479 
  2480 New in Isabelle94-6
  2481 -------------------
  2482 
  2483 * oracles -- these establish an interface between Isabelle and trusted
  2484 external reasoners, which may deliver results as theorems;
  2485 
  2486 * proof objects (in particular record all uses of oracles);
  2487 
  2488 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2489 
  2490 * "constdefs" section in theory files;
  2491 
  2492 * "primrec" section (HOL) no longer requires names;
  2493 
  2494 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2495 
  2496 
  2497 
  2498 New in Isabelle94-5
  2499 -------------------
  2500 
  2501 * reduced space requirements;
  2502 
  2503 * automatic HTML generation from theories;
  2504 
  2505 * theory files no longer require "..." (quotes) around most types;
  2506 
  2507 * new examples, including two proofs of the Church-Rosser theorem;
  2508 
  2509 * non-curried (1994) version of HOL is no longer distributed;
  2510 
  2511 
  2512 
  2513 New in Isabelle94-4
  2514 -------------------
  2515 
  2516 * greatly reduced space requirements;
  2517 
  2518 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2519 
  2520 * searchable theorem database (see the section "Retrieving theorems" on
  2521 page 8 of the Reference Manual);
  2522 
  2523 * new examples, including Grabczewski's monumental case study of the
  2524 Axiom of Choice;
  2525 
  2526 * The previous version of HOL renamed to Old_HOL;
  2527 
  2528 * The new version of HOL (previously called CHOL) uses a curried syntax
  2529 for functions.  Application looks like f a b instead of f(a,b);
  2530 
  2531 * Mutually recursive inductive definitions finally work in HOL;
  2532 
  2533 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2534 translates to the operator "split";
  2535 
  2536 
  2537 
  2538 New in Isabelle94-3
  2539 -------------------
  2540 
  2541 * new infix operator, addss, allowing the classical reasoner to
  2542 perform simplification at each step of its search.  Example:
  2543         fast_tac (cs addss ss)
  2544 
  2545 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2546 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2547 look like (a,b) instead of <a,b>;
  2548 
  2549 * PLEASE NOTE: CHOL will eventually replace HOL!
  2550 
  2551 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2552 It translates to the operator "split".  A new theory of integers is available;
  2553 
  2554 * In ZF, integer numerals now denote two's-complement binary integers.
  2555 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2556 
  2557 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2558 of the Axiom of Choice;
  2559 
  2560 
  2561 
  2562 New in Isabelle94-2
  2563 -------------------
  2564 
  2565 * Significantly faster resolution;
  2566 
  2567 * the different sections in a .thy file can now be mixed and repeated
  2568 freely;
  2569 
  2570 * Database of theorems for FOL, HOL and ZF.  New
  2571 commands including qed, qed_goal and bind_thm store theorems in the database.
  2572 
  2573 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2574 a given theory (thms_of), or find out what theory a theorem was proved in
  2575 (theory_of_thm);
  2576 
  2577 * Bugs fixed in the inductive definition and datatype packages;
  2578 
  2579 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2580 and HOL_dup_cs obsolete;
  2581 
  2582 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2583 have been removed;
  2584 
  2585 * Simpler definition of function space in ZF;
  2586 
  2587 * new results about cardinal and ordinal arithmetic in ZF;
  2588 
  2589 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2590 types;
  2591 
  2592 
  2593 $Id$