NEWS
author oheimb
Mon Apr 12 12:52:08 2004 +0200 (2004-04-12)
changeset 14536 43e436a4f293
parent 14508 859b11514537
child 14547 e0c0179100c9
permissions -rw-r--r--
added HOLCF/Streams.thy (with concatenation etc.)
     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 *** HOLCF ***
   163 
   164 * Streams now come with concatenation and are part of the HOLCF image
   165 
   166 New in Isabelle2003 (May 2003)
   167 --------------------------------
   168 
   169 *** General ***
   170 
   171 * Provers/simplifier:
   172 
   173   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   174     Assumptions are now subject to complete mutual simplification,
   175     not just from left to right. The simplifier now preserves
   176     the order of assumptions.
   177 
   178     Potential INCOMPATIBILITY:
   179 
   180     -- simp sometimes diverges where the old version did
   181        not, e.g. invoking simp on the goal
   182 
   183         [| P (f x); y = x; f x = f y |] ==> Q
   184 
   185        now gives rise to the infinite reduction sequence
   186 
   187         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   188 
   189        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   190        kind of problem.
   191 
   192     -- Tactics combining classical reasoner and simplification (such as auto)
   193        are also affected by this change, because many of them rely on
   194        simp. They may sometimes diverge as well or yield a different numbers
   195        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   196        in case of problems. Sometimes subsequent calls to the classical
   197        reasoner will fail because a preceeding call to the simplifier too
   198        eagerly simplified the goal, e.g. deleted redundant premises.
   199 
   200   - The simplifier trace now shows the names of the applied rewrite rules
   201 
   202   - You can limit the number of recursive invocations of the simplifier
   203     during conditional rewriting (where the simplifie tries to solve the
   204     conditions before applying the rewrite rule):
   205     ML "simp_depth_limit := n"
   206     where n is an integer. Thus you can force termination where previously
   207     the simplifier would diverge.
   208 
   209   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   210 
   211   - No longer aborts on failed congruence proof.  Instead, the
   212     congruence is ignored.
   213 
   214 * Pure: New generic framework for extracting programs from constructive
   215   proofs. See HOL/Extraction.thy for an example instantiation, as well
   216   as HOL/Extraction for some case studies.
   217 
   218 * Pure: The main goal of the proof state is no longer shown by default, only
   219 the subgoals. This behaviour is controlled by a new flag.
   220    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   221 (ML: Proof.show_main_goal).
   222 
   223 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   224 rules whose conclusion matches subgoal 1:
   225       PG menu: Isabelle/Isar -> Show me -> matching rules
   226 The rules are ordered by how closely they match the subgoal.
   227 In particular, rules that solve a subgoal outright are displayed first
   228 (or rather last, the way they are printed).
   229 (ML: ProofGeneral.print_intros())
   230 
   231 * Pure: New flag trace_unify_fail causes unification to print
   232 diagnostic information (PG: in trace buffer) when it fails. This is
   233 useful for figuring out why single step proofs like rule, erule or
   234 assumption failed.
   235 
   236 * Pure: Locale specifications now produce predicate definitions
   237 according to the body of text (covering assumptions modulo local
   238 definitions); predicate "loc_axioms" covers newly introduced text,
   239 while "loc" is cumulative wrt. all included locale expressions; the
   240 latter view is presented only on export into the global theory
   241 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   242 on the old view without predicates;
   243 
   244 * Pure: predefined locales "var" and "struct" are useful for sharing
   245 parameters (as in CASL, for example); just specify something like
   246 ``var x + var y + struct M'' as import;
   247 
   248 * Pure: improved thms_containing: proper indexing of facts instead of
   249 raw theorems; check validity of results wrt. current name space;
   250 include local facts of proof configuration (also covers active
   251 locales), cover fixed variables in index; may use "_" in term
   252 specification; an optional limit for the number of printed facts may
   253 be given (the default is 40);
   254 
   255 * Pure: disallow duplicate fact bindings within new-style theory files
   256 (batch-mode only);
   257 
   258 * Provers: improved induct method: assumptions introduced by case
   259 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   260 the goal statement); "foo" still refers to all facts collectively;
   261 
   262 * Provers: the function blast.overloaded has been removed: all constants
   263 are regarded as potentially overloaded, which improves robustness in exchange
   264 for slight decrease in efficiency;
   265 
   266 * Provers/linorder: New generic prover for transitivity reasoning over
   267 linear orders.  Note: this prover is not efficient!
   268 
   269 * Isar: preview of problems to finish 'show' now produce an error
   270 rather than just a warning (in interactive mode);
   271 
   272 
   273 *** HOL ***
   274 
   275 * arith(_tac)
   276 
   277  - Produces a counter example if it cannot prove a goal.
   278    Note that the counter example may be spurious if the goal is not a formula
   279    of quantifier-free linear arithmetic.
   280    In ProofGeneral the counter example appears in the trace buffer.
   281 
   282  - Knows about div k and mod k where k is a numeral of type nat or int.
   283 
   284  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   285    linear arithmetic fails. This takes account of quantifiers and divisibility.
   286    Presburger arithmetic can also be called explicitly via presburger(_tac). 
   287 
   288 * simp's arithmetic capabilities have been enhanced a bit: it now
   289 takes ~= in premises into account (by performing a case split);
   290 
   291 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   292 are distributed over a sum of terms;
   293 
   294 * New tactic "trans_tac" and method "trans" instantiate
   295 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   296 "<=", "<" and "="). 
   297 
   298 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main 
   299 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   300 
   301 * 'typedef' command has new option "open" to suppress the set
   302 definition;
   303 
   304 * functions Min and Max on finite sets have been introduced (theory
   305 Finite_Set);
   306 
   307 * attribute [symmetric] now works for relations as well; it turns
   308 (x,y) : R^-1 into (y,x) : R, and vice versa;
   309 
   310 * induct over a !!-quantified statement (say !!x1..xn):
   311   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   312 
   313 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   314 %x. None. Warning: empty_def now refers to the previously hidden definition
   315 of the empty set.
   316 
   317 * Algebra: formalization of classical algebra.  Intended as base for
   318 any algebraic development in Isabelle.  Currently covers group theory
   319 (up to Sylow's theorem) and ring theory (Universal Property of
   320 Univariate Polynomials).  Contributions welcome;
   321 
   322 * GroupTheory: deleted, since its material has been moved to Algebra;
   323 
   324 * Complex: new directory of the complex numbers with numeric constants, 
   325 nonstandard complex numbers, and some complex analysis, standard and 
   326 nonstandard (Jacques Fleuriot);
   327 
   328 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   329 
   330 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques 
   331 Fleuriot);
   332 
   333 * Real/HahnBanach: updated and adapted to locales;
   334 
   335 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   336 Gray and Kramer);
   337 
   338 * UNITY: added the Meier-Sanders theory of progress sets;
   339 
   340 * MicroJava: bytecode verifier and lightweight bytecode verifier
   341 as abstract algorithms, instantiated to the JVM;
   342 
   343 * Bali: Java source language formalization. Type system, operational
   344 semantics, axiomatic semantics. Supported language features:
   345 classes, interfaces, objects,virtual methods, static methods,
   346 static/instance fields, arrays, access modifiers, definite
   347 assignment, exceptions.
   348 
   349 
   350 *** ZF ***
   351 
   352 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   353 universe, etc.);
   354 
   355 * Main ZF: virtually all theories converted to new-style format;
   356 
   357 
   358 *** ML ***
   359 
   360 * Pure: Tactic.prove provides sane interface for internal proofs;
   361 omits the infamous "standard" operation, so this is more appropriate
   362 than prove_goalw_cterm in many situations (e.g. in simprocs);
   363 
   364 * Pure: improved error reporting of simprocs;
   365 
   366 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   367 up simprocs;
   368 
   369 
   370 *** Document preparation ***
   371 
   372 * uses \par instead of \\ for line breaks in theory text. This may
   373 shift some page breaks in large documents. To get the old behaviour
   374 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   375 
   376 * minimized dependencies of isabelle.sty and isabellesym.sty on 
   377 other packages
   378 
   379 * \<euro> now needs package babel/greek instead of marvosym (which
   380 broke \Rightarrow)
   381 
   382 * normal size for \<zero>...\<nine> (uses \mathbf instead of 
   383 textcomp package)
   384 
   385 
   386 New in Isabelle2002 (March 2002)
   387 --------------------------------
   388 
   389 *** Document preparation ***
   390 
   391 * greatly simplified document preparation setup, including more
   392 graceful interpretation of isatool usedir -i/-d/-D options, and more
   393 instructive isatool mkdir; users should basically be able to get
   394 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   395 users may run a separate document processing stage manually like this:
   396 "isatool usedir -D output HOL Test && isatool document Test/output";
   397 
   398 * theory dependency graph may now be incorporated into documents;
   399 isatool usedir -g true will produce session_graph.eps/.pdf for use
   400 with \includegraphics of LaTeX;
   401 
   402 * proper spacing of consecutive markup elements, especially text
   403 blocks after section headings;
   404 
   405 * support bold style (for single symbols only), input syntax is like
   406 this: "\<^bold>\<alpha>" or "\<^bold>A";
   407 
   408 * \<bullet> is now output as bold \cdot by default, which looks much
   409 better in printed text;
   410 
   411 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   412 note that these symbols are currently unavailable in Proof General /
   413 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   414 
   415 * isatool latex no longer depends on changed TEXINPUTS, instead
   416 isatool document copies the Isabelle style files to the target
   417 location;
   418 
   419 
   420 *** Isar ***
   421 
   422 * Pure/Provers: improved proof by cases and induction;
   423   - 'case' command admits impromptu naming of parameters (such as
   424     "case (Suc n)");
   425   - 'induct' method divinates rule instantiation from the inductive
   426     claim; no longer requires excessive ?P bindings for proper
   427     instantiation of cases;
   428   - 'induct' method properly enumerates all possibilities of set/type
   429     rules; as a consequence facts may be also passed through *type*
   430     rules without further ado;
   431   - 'induct' method now derives symbolic cases from the *rulified*
   432     rule (before it used to rulify cases stemming from the internal
   433     atomized version); this means that the context of a non-atomic
   434     statement becomes is included in the hypothesis, avoiding the
   435     slightly cumbersome show "PROP ?case" form;
   436   - 'induct' may now use elim-style induction rules without chaining
   437     facts, using ``missing'' premises from the goal state; this allows
   438     rules stemming from inductive sets to be applied in unstructured
   439     scripts, while still benefitting from proper handling of non-atomic
   440     statements; NB: major inductive premises need to be put first, all
   441     the rest of the goal is passed through the induction;
   442   - 'induct' proper support for mutual induction involving non-atomic
   443     rule statements (uses the new concept of simultaneous goals, see
   444     below);
   445   - append all possible rule selections, but only use the first
   446     success (no backtracking);
   447   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   448   - undeclared rule case names default to numbers 1, 2, 3, ...;
   449   - added 'print_induct_rules' (covered by help item in recent Proof
   450     General versions);
   451   - moved induct/cases attributes to Pure, methods to Provers;
   452   - generic method setup instantiated for FOL and HOL;
   453 
   454 * Pure: support multiple simultaneous goal statements, for example
   455 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   456 meta-level mechanism, this acts as if several individual goals had
   457 been stated separately; in particular common proof methods need to be
   458 repeated in order to cover all claims; note that a single elimination
   459 step is *not* sufficient to establish the two conjunctions, so this
   460 fails:
   461 
   462   assume "A & B" then have A and B ..   (*".." fails*)
   463 
   464 better use "obtain" in situations as above; alternative refer to
   465 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   466 
   467 * Pure: proper integration with ``locales''; unlike the original
   468 version by Florian Kammüller, Isar locales package high-level proof
   469 contexts rather than raw logical ones (e.g. we admit to include
   470 attributes everywhere); operations on locales include merge and
   471 rename; support for implicit arguments (``structures''); simultaneous
   472 type-inference over imports and text; see also HOL/ex/Locales.thy for
   473 some examples;
   474 
   475 * Pure: the following commands have been ``localized'', supporting a
   476 target locale specification "(in name)": 'lemma', 'theorem',
   477 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   478 stored both within the locale and at the theory level (exported and
   479 qualified by the locale name);
   480 
   481 * Pure: theory goals may now be specified in ``long'' form, with
   482 ad-hoc contexts consisting of arbitrary locale elements. for example
   483 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   484 definitions may be given, too); the result is a meta-level rule with
   485 the context elements being discharged in the obvious way;
   486 
   487 * Pure: new proof command 'using' allows to augment currently used
   488 facts after a goal statement ('using' is syntactically analogous to
   489 'apply', but acts on the goal's facts only); this allows chained facts
   490 to be separated into parts given before and after a claim, as in
   491 ``from a and b have C using d and e <proof>'';
   492 
   493 * Pure: renamed "antecedent" case to "rule_context";
   494 
   495 * Pure: new 'judgment' command records explicit information about the
   496 object-logic embedding (used by several tools internally); no longer
   497 use hard-wired "Trueprop";
   498 
   499 * Pure: added 'corollary' command;
   500 
   501 * Pure: fixed 'token_translation' command;
   502 
   503 * Pure: removed obsolete 'exported' attribute;
   504 
   505 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   506 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   507 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   508 
   509 * Pure: method 'atomize' presents local goal premises as object-level
   510 statements (atomic meta-level propositions); setup controlled via
   511 rewrite rules declarations of 'atomize' attribute; example
   512 application: 'induct' method with proper rule statements in improper
   513 proof *scripts*;
   514 
   515 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   516 now consider the syntactic context of assumptions, giving a better
   517 chance to get type-inference of the arguments right (this is
   518 especially important for locales);
   519 
   520 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   521 mode;
   522 
   523 * Pure/obtain: the formal conclusion "thesis", being marked as
   524 ``internal'', may no longer be reference directly in the text;
   525 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   526 situations;
   527 
   528 * Pure: generic 'sym' attribute which declares a rule both as pure
   529 'elim?' and for the 'symmetric' operation;
   530 
   531 * Pure: marginal comments ``--'' may now occur just anywhere in the
   532 text; the fixed correlation with particular command syntax has been
   533 discontinued;
   534 
   535 * Pure: new method 'rules' is particularly well-suited for proof
   536 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   537 but often produces more compact proof terms with less detours;
   538 
   539 * Pure/Provers/classical: simplified integration with pure rule
   540 attributes and methods; the classical "intro?/elim?/dest?"
   541 declarations coincide with the pure ones; the "rule" method no longer
   542 includes classically swapped intros; "intro" and "elim" methods no
   543 longer pick rules from the context; also got rid of ML declarations
   544 AddXIs/AddXEs/AddXDs; all of this has some potential for
   545 INCOMPATIBILITY;
   546 
   547 * Provers/classical: attribute 'swapped' produces classical inversions
   548 of introduction rules;
   549 
   550 * Provers/simplifier: 'simplified' attribute may refer to explicit
   551 rules instead of full simplifier context; 'iff' attribute handles
   552 conditional rules;
   553 
   554 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   555 
   556 * HOL: 'recdef' now fails on unfinished automated proofs, use
   557 "(permissive)" option to recover old behavior;
   558 
   559 * HOL: 'inductive' no longer features separate (collective) attributes
   560 for 'intros' (was found too confusing);
   561 
   562 * HOL: properly declared induction rules less_induct and
   563 wf_induct_rule;
   564 
   565 
   566 *** HOL ***
   567 
   568 * HOL: moved over to sane numeral syntax; the new policy is as
   569 follows:
   570 
   571   - 0 and 1 are polymorphic constants, which are defined on any
   572   numeric type (nat, int, real etc.);
   573 
   574   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   575   binary representation internally;
   576 
   577   - type nat has special constructor Suc, and generally prefers Suc 0
   578   over 1::nat and Suc (Suc 0) over 2::nat;
   579 
   580 This change may cause significant problems of INCOMPATIBILITY; here
   581 are some hints on converting existing sources:
   582 
   583   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   584   entities, so expressions involving "-" (unary or binary minus) need
   585   to be spaced properly;
   586 
   587   - existing occurrences of "1" may need to be constraint "1::nat" or
   588   even replaced by Suc 0; similar for old "2";
   589 
   590   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   591 
   592   - remove all special provisions on numerals in proofs;
   593 
   594 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   595 representation (depends on bin_arith_simps in the default context);
   596 
   597 * HOL: symbolic syntax for x^2 (numeral 2);
   598 
   599 * HOL: the class of all HOL types is now called "type" rather than
   600 "term"; INCOMPATIBILITY, need to adapt references to this type class
   601 in axclass/classes, instance/arities, and (usually rare) occurrences
   602 in typings (of consts etc.); internally the class is called
   603 "HOL.type", ML programs should refer to HOLogic.typeS;
   604 
   605 * HOL/record package improvements:
   606   - new derived operations "fields" to build a partial record section,
   607     "extend" to promote a fixed record to a record scheme, and
   608     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   609     declared as simp by default;
   610   - shared operations ("more", "fields", etc.) now need to be always
   611     qualified) --- potential INCOMPATIBILITY;
   612   - removed "make_scheme" operations (use "make" with "extend") --
   613     INCOMPATIBILITY;
   614   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   615   - provides cases/induct rules for use with corresponding Isar
   616     methods (for concrete records, record schemes, concrete more
   617     parts, and schematic more parts -- in that order);
   618   - internal definitions directly based on a light-weight abstract
   619     theory of product types over typedef rather than datatype;
   620 
   621 * HOL: generic code generator for generating executable ML code from
   622 specifications; specific support for HOL constructs such as inductive
   623 datatypes and sets, as well as recursive functions; can be invoked
   624 via 'generate_code' theory section;
   625 
   626 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   627 
   628 * HOL: consolidated and renamed several theories.  In particular:
   629 	Ord.thy has been absorbed into HOL.thy
   630 	String.thy has been absorbed into List.thy
   631  
   632 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   633 (beware of argument permutation!);
   634 
   635 * HOL: linorder_less_split superseded by linorder_cases;
   636 
   637 * HOL/List: "nodups" renamed to "distinct";
   638 
   639 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   640 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   641   - Ex_def has changed, now need to use some_eq_ex
   642 
   643 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   644 in this (rare) case use:
   645 
   646   delSWrapper "split_all_tac"
   647   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   648 
   649 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   650 MAY FAIL;
   651 
   652 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   653 Isabelle's type classes, ^ on functions and relations has too general
   654 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   655 necessary to attach explicit type constraints;
   656 
   657 * HOL/Relation: the prefix name of the infix "O" has been changed from
   658 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   659 renamed accordingly (eg "compI" -> "rel_compI").
   660 
   661 * HOL: syntax translations now work properly with numerals and records
   662 expressions;
   663 
   664 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   665 of "lam" -- INCOMPATIBILITY;
   666 
   667 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   668 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   669 renamed "Product_Type.unit";
   670 
   671 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   672 
   673 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   674 the "cases" method);
   675 
   676 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   677 Florian Kammüller);
   678 
   679 * HOL/IMP: updated and converted to new-style theory format; several
   680 parts turned into readable document, with proper Isar proof texts and
   681 some explanations (by Gerwin Klein);
   682 
   683 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   684 
   685 * HOL-Hyperreal is now a logic image;
   686 
   687 
   688 *** HOLCF ***
   689 
   690 * Isar: consts/constdefs supports mixfix syntax for continuous
   691 operations;
   692 
   693 * Isar: domain package adapted to new-style theory format, e.g. see
   694 HOLCF/ex/Dnat.thy;
   695 
   696 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   697 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   698 lift.induct_tac, always use UU instead of Undef;
   699 
   700 * HOLCF/IMP: updated and converted to new-style theory;
   701 
   702 
   703 *** ZF ***
   704 
   705 * Isar: proper integration of logic-specific tools and packages,
   706 including theory commands '(co)inductive', '(co)datatype',
   707 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   708 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   709 
   710 * theory Main no longer includes AC; for the Axiom of Choice, base
   711 your theory on Main_ZFC;
   712 
   713 * the integer library now covers quotients and remainders, with many
   714 laws relating division to addition, multiplication, etc.;
   715 
   716 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   717 typeless version of the formalism;
   718 
   719 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   720 format;
   721 
   722 * ZF/Induct: new directory for examples of inductive definitions,
   723 including theory Multiset for multiset orderings; converted to
   724 new-style theory format;
   725 
   726 * ZF: many new theorems about lists, ordinals, etc.;
   727 
   728 
   729 *** General ***
   730 
   731 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   732 variable proof controls level of detail: 0 = no proofs (only oracle
   733 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   734 also ref manual for further ML interfaces;
   735 
   736 * Pure/axclass: removed obsolete ML interface
   737 goal_subclass/goal_arity;
   738 
   739 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   740 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   741 separate tokens, so expressions involving minus need to be spaced
   742 properly;
   743 
   744 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   745 rather than "infixl" or "infixr";
   746 
   747 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   748 sort constraint specifications in type inference; e.g. "x::_::foo"
   749 ensures that the type of "x" is of sort "foo" (but not necessarily a
   750 type variable);
   751 
   752 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   753 control output of nested => (types); the default behavior is
   754 "type_brackets";
   755 
   756 * Pure/syntax: builtin parse translation for "_constify" turns valued
   757 tokens into AST constants;
   758 
   759 * Pure/syntax: prefer later declarations of translations and print
   760 translation functions; potential INCOMPATIBILITY: need to reverse
   761 multiple declarations for same syntax element constant;
   762 
   763 * Pure/show_hyps reset by default (in accordance to existing Isar
   764 practice);
   765 
   766 * Provers/classical: renamed addaltern to addafter, addSaltern to
   767 addSafter;
   768 
   769 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   770 as well;
   771 
   772 * system: tested support for MacOS X; should be able to get Isabelle +
   773 Proof General to work in a plain Terminal after installing Poly/ML
   774 (e.g. from the Isabelle distribution area) and GNU bash alone
   775 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   776 support requires further installations, e.g. from
   777 http://fink.sourceforge.net/);
   778 
   779 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   780 
   781 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   782 of 40 MB), cf. ML_OPTIONS;
   783 
   784 * system: Proof General keywords specification is now part of the
   785 Isabelle distribution (see etc/isar-keywords.el);
   786 
   787 * system: support for persistent Proof General sessions (refrain from
   788 outdating all loaded theories on startup); user may create writable
   789 logic images like this: ``isabelle -q HOL Test'';
   790 
   791 * system: smart selection of Isabelle process versus Isabelle
   792 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   793 run both "isabelle" and "Isabelle" even if file names are badly
   794 damaged (executable inspects the case of the first letter of its own
   795 name); added separate "isabelle-process" and "isabelle-interface";
   796 
   797 * system: refrain from any attempt at filtering input streams; no
   798 longer support ``8bit'' encoding of old isabelle font, instead proper
   799 iso-latin characters may now be used; the related isatools
   800 "symbolinput" and "nonascii" have disappeared as well;
   801 
   802 * system: removed old "xterm" interface (the print modes "xterm" and
   803 "xterm_color" are still available for direct use in a suitable
   804 terminal);
   805 
   806 
   807 
   808 New in Isabelle99-2 (February 2001)
   809 -----------------------------------
   810 
   811 *** Overview of INCOMPATIBILITIES ***
   812 
   813 * HOL: please note that theories in the Library and elsewhere often use the
   814 new-style (Isar) format; to refer to their theorems in an ML script you must
   815 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   816 
   817 * HOL: inductive package no longer splits induction rule aggressively,
   818 but only as far as specified by the introductions given; the old
   819 format may be recovered via ML function complete_split_rule or attribute
   820 'split_rule (complete)';
   821 
   822 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   823 gfp_Tarski to gfp_unfold;
   824 
   825 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   826 
   827 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   828 relation); infix "^^" has been renamed "``"; infix "``" has been
   829 renamed "`"; "univalent" has been renamed "single_valued";
   830 
   831 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   832 operation;
   833 
   834 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   835 
   836 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   837 
   838 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   839 consequence, it is no longer monotonic wrt. the local goal context
   840 (which is now passed through the inductive cases);
   841 
   842 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   843 \<gg> to \<ggreater>;
   844 
   845 
   846 *** Document preparation ***
   847 
   848 * \isabellestyle{NAME} selects version of Isabelle output (currently
   849 available: are "it" for near math-mode best-style output, "sl" for
   850 slanted text style, and "tt" for plain type-writer; if no
   851 \isabellestyle command is given, output is according to slanted
   852 type-writer);
   853 
   854 * support sub/super scripts (for single symbols only), input syntax is
   855 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   856 
   857 * some more standard symbols; see Appendix A of the system manual for
   858 the complete list of symbols defined in isabellesym.sty;
   859 
   860 * improved isabelle style files; more abstract symbol implementation
   861 (should now use \isamath{...} and \isatext{...} in custom symbol
   862 definitions);
   863 
   864 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   865 state; Note that presentation of goal states does not conform to
   866 actual human-readable proof documents.  Please do not include goal
   867 states into document output unless you really know what you are doing!
   868 
   869 * proper indentation of antiquoted output with proportional LaTeX
   870 fonts;
   871 
   872 * no_document ML operator temporarily disables LaTeX document
   873 generation;
   874 
   875 * isatool unsymbolize tunes sources for plain ASCII communication;
   876 
   877 
   878 *** Isar ***
   879 
   880 * Pure: Isar now suffers initial goal statements to contain unbound
   881 schematic variables (this does not conform to actual readable proof
   882 documents, due to unpredictable outcome and non-compositional proof
   883 checking); users who know what they are doing may use schematic goals
   884 for Prolog-style synthesis of proven results;
   885 
   886 * Pure: assumption method (an implicit finishing) now handles actual
   887 rules as well;
   888 
   889 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   890 initial goal, declare "that" only as Pure intro (only for single
   891 steps); the "that" rule assumption may now be involved in implicit
   892 finishing, thus ".." becomes a feasible for trivial obtains;
   893 
   894 * Pure: default proof step now includes 'intro_classes'; thus trivial
   895 instance proofs may be performed by "..";
   896 
   897 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   898 statements as well;
   899 
   900 * Pure: more robust selection of calculational rules;
   901 
   902 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   903 rule (as well as the assumption rule);
   904 
   905 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   906 lemmas, using the graph browser tool;
   907 
   908 * Pure: predict failure of "show" in interactive mode;
   909 
   910 * Pure: 'thms_containing' now takes actual terms as arguments;
   911 
   912 * HOL: improved method 'induct' --- now handles non-atomic goals
   913 (potential INCOMPATIBILITY); tuned error handling;
   914 
   915 * HOL: cases and induct rules now provide explicit hints about the
   916 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   917 any remaining facts are inserted into the goal verbatim;
   918 
   919 * HOL: local contexts (aka cases) may now contain term bindings as
   920 well; the 'cases' and 'induct' methods new provide a ?case binding for
   921 the result to be shown in each case;
   922 
   923 * HOL: added 'recdef_tc' command;
   924 
   925 * isatool convert assists in eliminating legacy ML scripts;
   926 
   927 
   928 *** HOL ***
   929 
   930 * HOL/Library: a collection of generic theories to be used together
   931 with main HOL; the theory loader path already includes this directory
   932 by default; the following existing theories have been moved here:
   933 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   934 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   935 
   936 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   937 modelling and verification task performed in Isabelle/HOL +
   938 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   939 
   940 * HOL/Algebra: special summation operator SUM no longer exists, it has
   941 been replaced by setsum; infix 'assoc' now has priority 50 (like
   942 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   943 'domain', this makes the theory consistent with mathematical
   944 literature;
   945 
   946 * HOL basics: added overloaded operations "inverse" and "divide"
   947 (infix "/"), syntax for generic "abs" operation, generic summation
   948 operator \<Sum>;
   949 
   950 * HOL/typedef: simplified package, provide more useful rules (see also
   951 HOL/subset.thy);
   952 
   953 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   954 now expressed as a proper nested rule (old-style tactic scripts may
   955 require atomize_strip_tac to cope with non-atomic premises);
   956 
   957 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   958 to "split_conv" (old name still available for compatibility);
   959 
   960 * HOL: improved concrete syntax for strings (e.g. allows translation
   961 rules with string literals);
   962 
   963 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   964  and Fleuriot's mechanization of analysis, including the transcendental
   965  functions for the reals;
   966 
   967 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   968 
   969 
   970 *** CTT ***
   971 
   972 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   973 "lam" is displayed as TWO lambda-symbols
   974 
   975 * CTT: theory Main now available, containing everything (that is, Bool
   976 and Arith);
   977 
   978 
   979 *** General ***
   980 
   981 * Pure: the Simplifier has been implemented properly as a derived rule
   982 outside of the actual kernel (at last!); the overall performance
   983 penalty in practical applications is about 50%, while reliability of
   984 the Isabelle inference kernel has been greatly improved;
   985 
   986 * print modes "brackets" and "no_brackets" control output of nested =>
   987 (types) and ==> (props); the default behaviour is "brackets";
   988 
   989 * Provers: fast_tac (and friends) now handle actual object-logic rules
   990 as assumptions as well;
   991 
   992 * system: support Poly/ML 4.0;
   993 
   994 * system: isatool install handles KDE version 1 or 2;
   995 
   996 
   997 
   998 New in Isabelle99-1 (October 2000)
   999 ----------------------------------
  1000 
  1001 *** Overview of INCOMPATIBILITIES ***
  1002 
  1003 * HOL: simplification of natural numbers is much changed; to partly
  1004 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
  1005 issue the following ML commands:
  1006 
  1007   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
  1008   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
  1009 
  1010 * HOL: simplification no longer dives into case-expressions; this is
  1011 controlled by "t.weak_case_cong" for each datatype t;
  1012 
  1013 * HOL: nat_less_induct renamed to less_induct;
  1014 
  1015 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
  1016 fixsome to patch .thy and .ML sources automatically;
  1017 
  1018   select_equality  -> some_equality
  1019   select_eq_Ex     -> some_eq_ex
  1020   selectI2EX       -> someI2_ex
  1021   selectI2         -> someI2
  1022   selectI          -> someI
  1023   select1_equality -> some1_equality
  1024   Eps_sym_eq       -> some_sym_eq_trivial
  1025   Eps_eq           -> some_eq_trivial
  1026 
  1027 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
  1028 
  1029 * HOL: removed obsolete theorem binding expand_if (refer to split_if
  1030 instead);
  1031 
  1032 * HOL: the recursion equations generated by 'recdef' are now called
  1033 f.simps instead of f.rules;
  1034 
  1035 * HOL: qed_spec_mp now also handles bounded ALL as well;
  1036 
  1037 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  1038 sometimes be needed;
  1039 
  1040 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  1041 
  1042 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  1043 
  1044 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  1045 product is now "<*>" instead of "Times"; the lexicographic product is
  1046 now "<*lex*>" instead of "**";
  1047 
  1048 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  1049 of main HOL, but was unused); better use HOL's datatype package;
  1050 
  1051 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  1052 the old syntax may be recovered as follows:
  1053 
  1054   syntax (symbols)
  1055     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  1056       (infixl "\\<oplus>" 100)
  1057 
  1058 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1059 
  1060 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1061 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1062 internally;
  1063 
  1064 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1065 changed from A/r to A//r;
  1066 
  1067 * ZF: new treatment of arithmetic (nat & int) may break some old
  1068 proofs;
  1069 
  1070 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1071 rulify -> rule_format, elimify -> elim_format, ...);
  1072 
  1073 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1074 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1075 should have to change intro!! to intro? only); replaced "delrule" by
  1076 "rule del";
  1077 
  1078 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1079 
  1080 * Provers: strengthened force_tac by using new first_best_tac;
  1081 
  1082 * LaTeX document preparation: several changes of isabelle.sty (see
  1083 lib/texinputs);
  1084 
  1085 
  1086 *** Document preparation ***
  1087 
  1088 * formal comments (text blocks etc.) in new-style theories may now
  1089 contain antiquotations of thm/prop/term/typ/text to be presented
  1090 according to latex print mode; concrete syntax is like this:
  1091 @{term[show_types] "f(x) = a + x"};
  1092 
  1093 * isatool mkdir provides easy setup of Isabelle session directories,
  1094 including proper document sources;
  1095 
  1096 * generated LaTeX sources are now deleted after successful run
  1097 (isatool document -c); may retain a copy somewhere else via -D option
  1098 of isatool usedir;
  1099 
  1100 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1101 style files, achieving self-contained LaTeX sources and simplifying
  1102 LaTeX debugging;
  1103 
  1104 * old-style theories now produce (crude) LaTeX output as well;
  1105 
  1106 * browser info session directories are now self-contained (may be put
  1107 on WWW server seperately); improved graphs of nested sessions; removed
  1108 graph for 'all sessions';
  1109 
  1110 * several improvements in isabelle style files; \isabellestyle{it}
  1111 produces fake math mode output; \isamarkupheader is now \section by
  1112 default; see lib/texinputs/isabelle.sty etc.;
  1113 
  1114 
  1115 *** Isar ***
  1116 
  1117 * Isar/Pure: local results and corresponding term bindings are now
  1118 subject to Hindley-Milner polymorphism (similar to ML); this
  1119 accommodates incremental type-inference very nicely;
  1120 
  1121 * Isar/Pure: new derived language element 'obtain' supports
  1122 generalized existence reasoning;
  1123 
  1124 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1125 support accumulation of results, without applying any rules yet;
  1126 useful to collect intermediate results without explicit name
  1127 references, and for use with transitivity rules with more than 2
  1128 premises;
  1129 
  1130 * Isar/Pure: scalable support for case-analysis type proofs: new
  1131 'case' language element refers to local contexts symbolically, as
  1132 produced by certain proof methods; internally, case names are attached
  1133 to theorems as "tags";
  1134 
  1135 * Isar/Pure: theory command 'hide' removes declarations from
  1136 class/type/const name spaces;
  1137 
  1138 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1139 indicate potential overloading;
  1140 
  1141 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1142 
  1143 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1144 "{a,b,c}" instead of {a,b,c};
  1145 
  1146 * Isar/Pure now provides its own version of intro/elim/dest
  1147 attributes; useful for building new logics, but beware of confusion
  1148 with the version in Provers/classical;
  1149 
  1150 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1151 case name 'antecedent';
  1152 
  1153 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1154 to the current context is now done automatically);
  1155 
  1156 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1157 for definining proof methods in ML;
  1158 
  1159 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1160 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1161 most cases, one should have to change intro!! to intro? only);
  1162 replaced "delrule" by "rule del";
  1163 
  1164 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1165 'symmetric' attribute (the latter supercedes [RS sym]);
  1166 
  1167 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1168 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1169 well (including splits);
  1170 
  1171 * Isar/Provers: Simplifier and Classical methods now support all kind
  1172 of modifiers used in the past, including 'cong', 'iff', etc.
  1173 
  1174 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1175 of Simplifier and Classical reasoner);
  1176 
  1177 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1178 now support named cases; major packages (inductive, datatype, primrec,
  1179 recdef) support case names and properly name parameters;
  1180 
  1181 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1182 monotonicity conditions are extracted to be proven at end of
  1183 calculations;
  1184 
  1185 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1186 method anyway;
  1187 
  1188 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1189 split_if split_if_asm; datatype package provides theorems foo.splits =
  1190 foo.split foo.split_asm for each datatype;
  1191 
  1192 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1193 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1194 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1195 use "(cases (simplified))" method in proper proof texts);
  1196 
  1197 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1198 
  1199 * Isar: names of theorems etc. may be natural numbers as well;
  1200 
  1201 * Isar: 'pr' command: optional arguments for goals_limit and
  1202 ProofContext.prems_limit; no longer prints theory contexts, but only
  1203 proof states;
  1204 
  1205 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1206 additional print modes to be specified; e.g. "pr(latex)" will print
  1207 proof state according to the Isabelle LaTeX style;
  1208 
  1209 * Isar: improved support for emulating tactic scripts, including proof
  1210 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1211 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1212 (for HOL datatypes);
  1213 
  1214 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1215 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1216 'proof method scripts' have to be in depth-first order;
  1217 
  1218 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1219 
  1220 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1221 should instead use individual commands for printing items
  1222 (print_commands, print_methods etc.);
  1223 
  1224 * Isar: added 'nothing' --- the empty list of theorems;
  1225 
  1226 
  1227 *** HOL ***
  1228 
  1229 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1230 corresponding virtual machine and a specification of its bytecode
  1231 verifier and a lightweight bytecode verifier, including proofs of
  1232 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1233 Cornelia Pusch (see also the homepage of project Bali at
  1234 http://isabelle.in.tum.de/Bali/);
  1235 
  1236 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1237 Clemens Ballarin;
  1238 
  1239 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1240 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1241 Rasmussen;
  1242 
  1243 * HOL/Lattice: fundamental concepts of lattice theory and order
  1244 structures, including duals, properties of bounds versus algebraic
  1245 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1246 Theorem for complete lattices etc.; may also serve as a demonstration
  1247 for abstract algebraic reasoning using axiomatic type classes, and
  1248 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1249 
  1250 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1251 von Oheimb;
  1252 
  1253 * HOL/IMPP: extension of IMP with local variables and mutually
  1254 recursive procedures, by David von Oheimb;
  1255 
  1256 * HOL/Lambda: converted into new-style theory and document;
  1257 
  1258 * HOL/ex/Multiquote: example of multiple nested quotations and
  1259 anti-quotations -- basically a generalized version of de-Bruijn
  1260 representation; very useful in avoiding lifting of operations;
  1261 
  1262 * HOL/record: added general record equality rule to simpset; fixed
  1263 select-update simplification procedure to handle extended records as
  1264 well; admit "r" as field name;
  1265 
  1266 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1267 other numeric types and also as the identity of groups, rings, etc.;
  1268 
  1269 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1270 Types nat and int belong to this axclass;
  1271 
  1272 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1273    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1274    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1275   two terms #m*u and #n*u are replaced by #(m+n)*u
  1276     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1277   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1278     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1279 
  1280 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1281 powerful prover for predicate logic but knows nothing of clasets; see
  1282 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1283 
  1284 * HOL: new version of "case_tac" subsumes both boolean case split and
  1285 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1286 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1287 
  1288 * HOL: simplification no longer dives into case-expressions: only the
  1289 selector expression is simplified, but not the remaining arms; to
  1290 enable full simplification of case-expressions for datatype t, you may
  1291 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1292 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1293 
  1294 * HOL/recdef: the recursion equations generated by 'recdef' for
  1295 function 'f' are now called f.simps instead of f.rules; if all
  1296 termination conditions are proved automatically, these simplification
  1297 rules are added to the simpset, as in primrec; rules may be named
  1298 individually as well, resulting in a separate list of theorems for
  1299 each equation;
  1300 
  1301 * HOL/While is a new theory that provides a while-combinator. It
  1302 permits the definition of tail-recursive functions without the
  1303 provision of a termination measure. The latter is necessary once the
  1304 invariant proof rule for while is applied.
  1305 
  1306 * HOL: new (overloaded) notation for the set of elements below/above
  1307 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1308 
  1309 * HOL: theorems impI, allI, ballI bound as "strip";
  1310 
  1311 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1312 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1313 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1314 
  1315 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1316 
  1317 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1318 main HOL, but was unused);
  1319 
  1320 * HOL: fewer consts declared as global (e.g. have to refer to
  1321 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1322 
  1323 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1324 in case of overlap with user translations (e.g. judgements over
  1325 tuples); (note that the underlying logical represenation is still
  1326 bogus);
  1327 
  1328 
  1329 *** ZF ***
  1330 
  1331 * ZF: simplification automatically cancels common terms in arithmetic
  1332 expressions over nat and int;
  1333 
  1334 * ZF: new treatment of nat to minimize type-checking: all operators
  1335 coerce their operands to a natural number using the function natify,
  1336 making the algebraic laws unconditional;
  1337 
  1338 * ZF: as above, for int: operators coerce their operands to an integer
  1339 using the function intify;
  1340 
  1341 * ZF: the integer library now contains many of the usual laws for the
  1342 orderings, including $<=, and monotonicity laws for $+ and $*;
  1343 
  1344 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1345 simplification;
  1346 
  1347 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1348 to the simplifier and classical reasoner simultaneously;
  1349 
  1350 
  1351 *** General ***
  1352 
  1353 * Provers: blast_tac now handles actual object-logic rules as
  1354 assumptions; note that auto_tac uses blast_tac internally as well;
  1355 
  1356 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1357 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1358 
  1359 * Provers: delrules now handles destruct rules as well (no longer need
  1360 explicit make_elim);
  1361 
  1362 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1363   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1364 use instead the strong form,
  1365   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1366 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1367 from destruct-rules;
  1368 
  1369 * Provers: Simplifier.easy_setup provides a fast path to basic
  1370 Simplifier setup for new object-logics;
  1371 
  1372 * Pure: AST translation rules no longer require constant head on LHS;
  1373 
  1374 * Pure: improved name spaces: ambiguous output is qualified; support
  1375 for hiding of names;
  1376 
  1377 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1378 XSYMBOL_HOME; no longer need to do manual configuration in most
  1379 situations;
  1380 
  1381 * system: compression of ML heaps images may now be controlled via -c
  1382 option of isabelle and isatool usedir (currently only observed by
  1383 Poly/ML);
  1384 
  1385 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1386 useful for remote X11);
  1387 
  1388 * system: provide TAGS file for Isabelle sources;
  1389 
  1390 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1391 order;
  1392 
  1393 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1394 timing flag supersedes proof_timing and Toplevel.trace;
  1395 
  1396 * ML: new combinators |>> and |>>> for incremental transformations
  1397 with secondary results (e.g. certain theory extensions):
  1398 
  1399 * ML: PureThy.add_defs gets additional argument to indicate potential
  1400 overloading (usually false);
  1401 
  1402 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1403 results;
  1404 
  1405 
  1406 
  1407 New in Isabelle99 (October 1999)
  1408 --------------------------------
  1409 
  1410 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1411 
  1412 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1413 are no longer simplified.  (This allows the simplifier to unfold recursive
  1414 functional programs.)  To restore the old behaviour, declare
  1415 
  1416     Delcongs [if_weak_cong];
  1417 
  1418 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1419 complement;
  1420 
  1421 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1422 
  1423 * HOL/datatype: mutual_induct_tac no longer exists --
  1424   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1425 
  1426 * HOL/typedef: fixed type inference for representing set; type
  1427 arguments now have to occur explicitly on the rhs as type constraints;
  1428 
  1429 * ZF: The con_defs part of an inductive definition may no longer refer
  1430 to constants declared in the same theory;
  1431 
  1432 * HOL, ZF: the function mk_cases, generated by the inductive
  1433 definition package, has lost an argument.  To simplify its result, it
  1434 uses the default simpset instead of a supplied list of theorems.
  1435 
  1436 * HOL/List: the constructors of type list are now Nil and Cons;
  1437 
  1438 * Simplifier: the type of the infix ML functions
  1439         setSSolver addSSolver setSolver addSolver
  1440 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1441 for packaging solvers. A solver is created via
  1442         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1443 where the string argument is only a comment.
  1444 
  1445 
  1446 *** Proof tools ***
  1447 
  1448 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1449 decision procedure for linear arithmetic. Currently it is used for
  1450 types `nat', `int', and `real' in HOL (see below); it can, should and
  1451 will be instantiated for other types and logics as well.
  1452 
  1453 * The simplifier now accepts rewrite rules with flexible heads, eg
  1454      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1455   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1456   matching.
  1457 
  1458 
  1459 *** General ***
  1460 
  1461 * New Isabelle/Isar subsystem provides an alternative to traditional
  1462 tactical theorem proving; together with the ProofGeneral/isar user
  1463 interface it offers an interactive environment for developing human
  1464 readable proof documents (Isar == Intelligible semi-automated
  1465 reasoning); for further information see isatool doc isar-ref,
  1466 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1467 
  1468 * improved and simplified presentation of theories: better HTML markup
  1469 (including colors), graph views in several sizes; isatool usedir now
  1470 provides a proper interface for user theories (via -P option); actual
  1471 document preparation based on (PDF)LaTeX is available as well (for
  1472 new-style theories only); see isatool doc system for more information;
  1473 
  1474 * native support for Proof General, both for classic Isabelle and
  1475 Isabelle/Isar;
  1476 
  1477 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1478 using the graph browser tool;
  1479 
  1480 * Isabelle manuals now also available as PDF;
  1481 
  1482 * theory loader rewritten from scratch (may not be fully
  1483 bug-compatible); old loadpath variable has been replaced by show_path,
  1484 add_path, del_path, reset_path functions; new operations such as
  1485 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1486 isatool doc ref);
  1487 
  1488 * improved isatool install: option -k creates KDE application icon,
  1489 option -p DIR installs standalone binaries;
  1490 
  1491 * added ML_PLATFORM setting (useful for cross-platform installations);
  1492 more robust handling of platform specific ML images for SML/NJ;
  1493 
  1494 * the settings environment is now statically scoped, i.e. it is never
  1495 created again in sub-processes invoked from isabelle, isatool, or
  1496 Isabelle;
  1497 
  1498 * path element specification '~~' refers to '$ISABELLE_HOME';
  1499 
  1500 * in locales, the "assumes" and "defines" parts may be omitted if
  1501 empty;
  1502 
  1503 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1504 long arrows);
  1505 
  1506 * new print_mode "HTML";
  1507 
  1508 * new flag show_tags controls display of tags of theorems (which are
  1509 basically just comments that may be attached by some tools);
  1510 
  1511 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1512 mode and goal output format:
  1513 
  1514 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1515 244c244
  1516 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1517 ---
  1518 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1519 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1520 181c181
  1521 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1522 ---
  1523 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1524 
  1525 * function bind_thms stores lists of theorems (cf. bind_thm);
  1526 
  1527 * new shorthand tactics ftac, eatac, datac, fatac;
  1528 
  1529 * qed (and friends) now accept "" as result name; in that case the
  1530 theorem is not stored, but proper checks and presentation of the
  1531 result still apply;
  1532 
  1533 * theorem database now also indexes constants "Trueprop", "all",
  1534 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1535 
  1536 
  1537 *** HOL ***
  1538 
  1539 ** HOL arithmetic **
  1540 
  1541 * There are now decision procedures for linear arithmetic over nat and
  1542 int:
  1543 
  1544 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1545 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1546 are treated as atomic; subformulae not involving type `nat' or `int'
  1547 are ignored; quantified subformulae are ignored unless they are
  1548 positive universal or negative existential. The tactic has to be
  1549 invoked by hand and can be a little bit slow. In particular, the
  1550 running time is exponential in the number of occurrences of `min' and
  1551 `max', and `-' on `nat'.
  1552 
  1553 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1554 (negated) (in)equalities among the premises and the conclusion into
  1555 account (i.e. no compound formulae) and does not know about `min' and
  1556 `max', and `-' on `nat'. It is fast and is used automatically by the
  1557 simplifier.
  1558 
  1559 NB: At the moment, these decision procedures do not cope with mixed
  1560 nat/int formulae where the two parts interact, such as `m < n ==>
  1561 int(m) < int(n)'.
  1562 
  1563 * HOL/Numeral provides a generic theory of numerals (encoded
  1564 efficiently as bit strings); setup for types nat/int/real is in place;
  1565 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1566 int, existing theories and proof scripts may require a few additional
  1567 type constraints;
  1568 
  1569 * integer division and remainder can now be performed on constant
  1570 arguments;
  1571 
  1572 * many properties of integer multiplication, division and remainder
  1573 are now available;
  1574 
  1575 * An interface to the Stanford Validity Checker (SVC) is available through the
  1576 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1577 are proved automatically.  SVC must be installed separately, and its results
  1578 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1579 invocation of the underlying oracle).  For SVC see
  1580   http://verify.stanford.edu/SVC
  1581 
  1582 * IsaMakefile: the HOL-Real target now builds an actual image;
  1583 
  1584 
  1585 ** HOL misc **
  1586 
  1587 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1588 (in Isabelle/Isar) -- by Gertrud Bauer;
  1589 
  1590 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1591 analysis for assembly languages with subtypes;
  1592 
  1593 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1594 -- avoids syntactic ambiguities and treats state, transition, and
  1595 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1596 changed syntax and (many) tactics;
  1597 
  1598 * HOL/inductive: Now also handles more general introduction rules such
  1599   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1600   theorems are now maintained within the theory (maintained via the
  1601   "mono" attribute);
  1602 
  1603 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1604   (using function types) such as
  1605 
  1606   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1607 
  1608 * HOL/record: record_simproc (part of the default simpset) takes care
  1609 of selectors applied to updated records; record_split_tac is no longer
  1610 part of the default claset; update_defs may now be removed from the
  1611 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1612 
  1613   claset_ref () := claset() addSWrapper record_split_wrapper;
  1614   Delsimprocs [record_simproc]
  1615 
  1616 * HOL/typedef: fixed type inference for representing set; type
  1617 arguments now have to occur explicitly on the rhs as type constraints;
  1618 
  1619 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1620 names rather than an ML expression;
  1621 
  1622 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1623 supplied later.  Program schemes can be defined, such as
  1624     "While B C s = (if B s then While B C (C s) else s)"
  1625 where the well-founded relation can be chosen after B and C have been given.
  1626 
  1627 * HOL/List: the constructors of type list are now Nil and Cons;
  1628 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1629 course, ML tools referring to List.list.op # etc. have to be adapted;
  1630 
  1631 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1632 disabled by default; run isabelle with option -m HOL to get back to
  1633 the original Gordon/HOL-style output;
  1634 
  1635 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1636 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1637 
  1638 * HOL basic syntax simplified (more orthogonal): all variants of
  1639 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1640 Eps operator is provided as well: "SOME x. P[x]";
  1641 
  1642 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1643 
  1644 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1645 thus available for user theories;
  1646 
  1647 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1648 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1649 time;
  1650 
  1651 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1652 several times and then mp;
  1653 
  1654 
  1655 *** LK ***
  1656 
  1657 * the notation <<...>> is now available as a notation for sequences of
  1658 formulas;
  1659 
  1660 * the simplifier is now installed
  1661 
  1662 * the axiom system has been generalized (thanks to Soren Heilmann)
  1663 
  1664 * the classical reasoner now has a default rule database
  1665 
  1666 
  1667 *** ZF ***
  1668 
  1669 * new primrec section allows primitive recursive functions to be given
  1670 directly (as in HOL) over datatypes and the natural numbers;
  1671 
  1672 * new tactics induct_tac and exhaust_tac for induction (or case
  1673 analysis) over datatypes and the natural numbers;
  1674 
  1675 * the datatype declaration of type T now defines the recursor T_rec;
  1676 
  1677 * simplification automatically does freeness reasoning for datatype
  1678 constructors;
  1679 
  1680 * automatic type-inference, with AddTCs command to insert new
  1681 type-checking rules;
  1682 
  1683 * datatype introduction rules are now added as Safe Introduction rules
  1684 to the claset;
  1685 
  1686 * the syntax "if P then x else y" is now available in addition to
  1687 if(P,x,y);
  1688 
  1689 
  1690 *** Internal programming interfaces ***
  1691 
  1692 * tuned simplifier trace output; new flag debug_simp;
  1693 
  1694 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1695 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1696 
  1697 * AxClass.axclass_tac lost the theory argument;
  1698 
  1699 * tuned current_goals_markers semantics: begin / end goal avoids
  1700 printing empty lines;
  1701 
  1702 * removed prs and prs_fn hook, which was broken because it did not
  1703 include \n in its semantics, forcing writeln to add one
  1704 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1705 string -> unit if you really want to output text without newline;
  1706 
  1707 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1708 plain output, interface builders may have to enable 'isabelle_font'
  1709 mode to get Isabelle font glyphs as before;
  1710 
  1711 * refined token_translation interface; INCOMPATIBILITY: output length
  1712 now of type real instead of int;
  1713 
  1714 * theory loader actions may be traced via new ThyInfo.add_hook
  1715 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1716 your own database of information attached to *whole* theories -- as
  1717 opposed to intra-theory data slots offered via TheoryDataFun;
  1718 
  1719 * proper handling of dangling sort hypotheses (at last!);
  1720 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1721 extra sort hypotheses that can be witnessed from the type signature;
  1722 the force_strip_shyps flag is gone, any remaining shyps are simply
  1723 left in the theorem (with a warning issued by strip_shyps_warning);
  1724 
  1725 
  1726 
  1727 New in Isabelle98-1 (October 1998)
  1728 ----------------------------------
  1729 
  1730 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1731 
  1732 * several changes of automated proof tools;
  1733 
  1734 * HOL: major changes to the inductive and datatype packages, including
  1735 some minor incompatibilities of theory syntax;
  1736 
  1737 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1738 called `inj_on';
  1739 
  1740 * HOL: removed duplicate thms in Arith:
  1741   less_imp_add_less  should be replaced by  trans_less_add1
  1742   le_imp_add_le      should be replaced by  trans_le_add1
  1743 
  1744 * HOL: unary minus is now overloaded (new type constraints may be
  1745 required);
  1746 
  1747 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1748 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1749 now taken as an integer constant.
  1750 
  1751 * Pure: ML function 'theory_of' renamed to 'theory';
  1752 
  1753 
  1754 *** Proof tools ***
  1755 
  1756 * Simplifier:
  1757   1. Asm_full_simp_tac is now more aggressive.
  1758      1. It will sometimes reorient premises if that increases their power to
  1759         simplify.
  1760      2. It does no longer proceed strictly from left to right but may also
  1761         rotate premises to achieve further simplification.
  1762      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1763      old Asm_full_simp_tac in that it does not rotate premises.
  1764   2. The simplifier now knows a little bit about nat-arithmetic.
  1765 
  1766 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1767 allows for selected deletion of wrappers, by introduction of names for
  1768 wrapper functionals.  This implies that addbefore, addSbefore,
  1769 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1770 and that adding two tactics with the same name overwrites the first
  1771 one (emitting a warning).
  1772   type wrapper = (int -> tactic) -> (int -> tactic)
  1773   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1774   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1775   delWrapper, delSWrapper: claset *  string            -> claset
  1776   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1777 
  1778 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1779 semantics; addbefore now affects only the unsafe part of step_tac
  1780 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1781 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1782 by Force_tac;
  1783 
  1784 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1785 compWrapper; added safe wrapper (and access functions for it);
  1786 
  1787 * HOL/split_all_tac is now much faster and fails if there is nothing
  1788 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1789 and the names of the automatically generated variables have changed.
  1790 split_all_tac has moved within claset() from unsafe wrappers to safe
  1791 wrappers, which means that !!-bound variables are split much more
  1792 aggressively, and safe_tac and clarify_tac now split such variables.
  1793 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1794 Note: the same holds for record_split_tac, which does the job of
  1795 split_all_tac for record fields.
  1796 
  1797 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1798 permanently to the default simpset using Addsplits just like
  1799 Addsimps. They can be removed via Delsplits just like
  1800 Delsimps. Lower-case versions are also available.
  1801 
  1802 * HOL/Simplifier: The rule split_if is now part of the default
  1803 simpset. This means that the simplifier will eliminate all occurrences
  1804 of if-then-else in the conclusion of a goal. To prevent this, you can
  1805 either remove split_if completely from the default simpset by
  1806 `Delsplits [split_if]' or remove it in a specific call of the
  1807 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1808 other case splitting rules to/from the default simpset: every datatype
  1809 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1810 t is the name of the datatype).
  1811 
  1812 * Classical reasoner / Simplifier combination: new force_tac (and
  1813 derivatives Force_tac, force) combines rewriting and classical
  1814 reasoning (and whatever other tools) similarly to auto_tac, but is
  1815 aimed to solve the given subgoal completely.
  1816 
  1817 
  1818 *** General ***
  1819 
  1820 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1821 and `goalw': the theory is no longer needed as an explicit argument -
  1822 the current theory context is used; assumptions are no longer returned
  1823 at the ML-level unless one of them starts with ==> or !!; it is
  1824 recommended to convert to these new commands using isatool fixgoal
  1825 (backup your sources first!);
  1826 
  1827 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1828 the current theory context, and 'theory' to lookup stored theories;
  1829 
  1830 * new theory section 'locale' for declaring constants, assumptions and
  1831 definitions that have local scope;
  1832 
  1833 * new theory section 'nonterminals' for purely syntactic types;
  1834 
  1835 * new theory section 'setup' for generic ML setup functions
  1836 (e.g. package initialization);
  1837 
  1838 * the distribution now includes Isabelle icons: see
  1839 lib/logo/isabelle-{small,tiny}.xpm;
  1840 
  1841 * isatool install - install binaries with absolute references to
  1842 ISABELLE_HOME/bin;
  1843 
  1844 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1845 
  1846 * print mode 'emacs' reserved for Isamode;
  1847 
  1848 * support multiple print (ast) translations per constant name;
  1849 
  1850 * theorems involving oracles are now printed with a suffixed [!];
  1851 
  1852 
  1853 *** HOL ***
  1854 
  1855 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1856 
  1857 * HOL/inductive package reorganized and improved: now supports mutual
  1858 definitions such as
  1859 
  1860   inductive EVEN ODD
  1861     intrs
  1862       null "0 : EVEN"
  1863       oddI "n : EVEN ==> Suc n : ODD"
  1864       evenI "n : ODD ==> Suc n : EVEN"
  1865 
  1866 new theorem list "elims" contains an elimination rule for each of the
  1867 recursive sets; inductive definitions now handle disjunctive premises
  1868 correctly (also ZF);
  1869 
  1870 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1871 "mutual_induct" no longer exists - the induction rule is always
  1872 contained in "induct";
  1873 
  1874 
  1875 * HOL/datatype package re-implemented and greatly improved: now
  1876 supports mutually recursive datatypes such as
  1877 
  1878   datatype
  1879     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1880             | SUM ('a aexp) ('a aexp)
  1881             | DIFF ('a aexp) ('a aexp)
  1882             | NUM 'a
  1883   and
  1884     'a bexp = LESS ('a aexp) ('a aexp)
  1885             | AND ('a bexp) ('a bexp)
  1886             | OR ('a bexp) ('a bexp)
  1887 
  1888 as well as indirectly recursive datatypes such as
  1889 
  1890   datatype
  1891     ('a, 'b) term = Var 'a
  1892                   | App 'b ((('a, 'b) term) list)
  1893 
  1894 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1895 induction on mutually / indirectly recursive datatypes.
  1896 
  1897 Primrec equations are now stored in theory and can be accessed via
  1898 <function_name>.simps.
  1899 
  1900 INCOMPATIBILITIES:
  1901 
  1902   - Theories using datatypes must now have theory Datatype as an
  1903     ancestor.
  1904   - The specific <typename>.induct_tac no longer exists - use the
  1905     generic induct_tac instead.
  1906   - natE has been renamed to nat.exhaust - use exhaust_tac
  1907     instead of res_inst_tac ... natE. Note that the variable
  1908     names in nat.exhaust differ from the names in natE, this
  1909     may cause some "fragile" proofs to fail.
  1910   - The theorems split_<typename>_case and split_<typename>_case_asm
  1911     have been renamed to <typename>.split and <typename>.split_asm.
  1912   - Since default sorts of type variables are now handled correctly,
  1913     some datatype definitions may have to be annotated with explicit
  1914     sort constraints.
  1915   - Primrec definitions no longer require function name and type
  1916     of recursive argument.
  1917 
  1918 Consider using isatool fixdatatype to adapt your theories and proof
  1919 scripts to the new package (backup your sources first!).
  1920 
  1921 
  1922 * HOL/record package: considerably improved implementation; now
  1923 includes concrete syntax for record types, terms, updates; theorems
  1924 for surjective pairing and splitting !!-bound record variables; proof
  1925 support is as follows:
  1926 
  1927   1) standard conversions (selectors or updates applied to record
  1928 constructor terms) are part of the standard simpset;
  1929 
  1930   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1931 made part of standard simpset and claset via addIffs;
  1932 
  1933   3) a tactic for record field splitting (record_split_tac) is part of
  1934 the standard claset (addSWrapper);
  1935 
  1936 To get a better idea about these rules you may retrieve them via
  1937 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1938 the name of your record type.
  1939 
  1940 The split tactic 3) conceptually simplifies by the following rule:
  1941 
  1942   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1943 
  1944 Thus any record variable that is bound by meta-all will automatically
  1945 blow up into some record constructor term, consequently the
  1946 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1947 solve record problems automatically.
  1948 
  1949 
  1950 * reorganized the main HOL image: HOL/Integ and String loaded by
  1951 default; theory Main includes everything;
  1952 
  1953 * automatic simplification of integer sums and comparisons, using cancellation;
  1954 
  1955 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1956 
  1957 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1958 
  1959 * many new identities for unions, intersections, set difference, etc.;
  1960 
  1961 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1962 called split_if, split_split, split_sum_case and split_nat_case (to go
  1963 with add/delsplits);
  1964 
  1965 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1966 (?x::unit) = (); this is made part of the default simpset, which COULD
  1967 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1968 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1969 unit_abs_eta_conv is added in order to counter the effect of
  1970 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1971 %u.f();
  1972 
  1973 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1974 makes more sense);
  1975 
  1976 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  1977   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  1978   disjointness reasoning but breaking a few old proofs.
  1979 
  1980 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  1981 to 'converse' from 'inverse' (for compatibility with ZF and some
  1982 literature);
  1983 
  1984 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  1985 the well-founded relation;
  1986 
  1987 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  1988     Compl A.  The "Compl" syntax remains available as input syntax for this
  1989     release ONLY.
  1990 
  1991 * HOL/Update: new theory of function updates:
  1992     f(a:=b) == %x. if x=a then b else f x
  1993 may also be iterated as in f(a:=b,c:=d,...);
  1994 
  1995 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  1996 
  1997 * HOL/List:
  1998   - new function list_update written xs[i:=v] that updates the i-th
  1999     list position. May also be iterated as in xs[i:=a,j:=b,...].
  2000   - new function `upt' written [i..j(] which generates the list
  2001     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  2002     bound write [i..j], which is a shorthand for [i..j+1(].
  2003   - new lexicographic orderings and corresponding wellfoundedness theorems.
  2004 
  2005 * HOL/Arith:
  2006   - removed 'pred' (predecessor) function;
  2007   - generalized some theorems about n-1;
  2008   - many new laws about "div" and "mod";
  2009   - new laws about greatest common divisors (see theory ex/Primes);
  2010 
  2011 * HOL/Relation: renamed the relational operator r^-1 "converse"
  2012 instead of "inverse";
  2013 
  2014 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  2015   of the multiset ordering;
  2016 
  2017 * directory HOL/Real: a construction of the reals using Dedekind cuts
  2018   (not included by default);
  2019 
  2020 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  2021 
  2022 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  2023   programs, i.e. different program variables may have different types.
  2024 
  2025 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2026   [previously, this check worked only if the rewrite rule was unconditional]
  2027   Now rew can involve either definitions or equalities (either == or =).
  2028 
  2029 
  2030 *** ZF ***
  2031 
  2032 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  2033   only the theorems proved on ZF.ML;
  2034 
  2035 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2036   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2037   disjointness reasoning but breaking a few old proofs.
  2038 
  2039 * ZF/Update: new theory of function updates
  2040     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  2041   may also be iterated as in f(a:=b,c:=d,...);
  2042 
  2043 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  2044 
  2045 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2046   [previously, this check worked only if the rewrite rule was unconditional]
  2047   Now rew can involve either definitions or equalities (either == or =).
  2048 
  2049 * case_tac provided for compatibility with HOL
  2050     (like the old excluded_middle_tac, but with subgoals swapped)
  2051 
  2052 
  2053 *** Internal programming interfaces ***
  2054 
  2055 * Pure: several new basic modules made available for general use, see
  2056 also src/Pure/README;
  2057 
  2058 * improved the theory data mechanism to support encapsulation (data
  2059 kind name replaced by private Object.kind, acting as authorization
  2060 key); new type-safe user interface via functor TheoryDataFun; generic
  2061 print_data function becomes basically useless;
  2062 
  2063 * removed global_names compatibility flag -- all theory declarations
  2064 are qualified by default;
  2065 
  2066 * module Pure/Syntax now offers quote / antiquote translation
  2067 functions (useful for Hoare logic etc. with implicit dependencies);
  2068 see HOL/ex/Antiquote for an example use;
  2069 
  2070 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2071 cterm -> thm;
  2072 
  2073 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2074 subgoal;
  2075 
  2076 * Display.print_goals function moved to Locale.print_goals;
  2077 
  2078 * standard print function for goals supports current_goals_markers
  2079 variable for marking begin of proof, end of proof, start of goal; the
  2080 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2081 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2082 for example;
  2083 
  2084 
  2085 
  2086 New in Isabelle98 (January 1998)
  2087 --------------------------------
  2088 
  2089 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2090 
  2091 * changed lexical syntax of terms / types: dots made part of long
  2092 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2093 
  2094 * simpset (and claset) reference variable replaced by functions
  2095 simpset / simpset_ref;
  2096 
  2097 * no longer supports theory aliases (via merge) and non-trivial
  2098 implicit merge of thms' signatures;
  2099 
  2100 * most internal names of constants changed due to qualified names;
  2101 
  2102 * changed Pure/Sequence interface (see Pure/seq.ML);
  2103 
  2104 
  2105 *** General Changes ***
  2106 
  2107 * hierachically structured name spaces (for consts, types, axms, thms
  2108 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2109 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2110 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2111 long_names for fully qualified output names; NOTE: ML programs
  2112 (special tactics, packages etc.) referring to internal names may have
  2113 to be adapted to cope with fully qualified names; in case of severe
  2114 backward campatibility problems try setting 'global_names' at compile
  2115 time to have enrything declared within a flat name space; one may also
  2116 fine tune name declarations in theories via the 'global' and 'local'
  2117 section;
  2118 
  2119 * reimplemented the implicit simpset and claset using the new anytype
  2120 data filed in signatures; references simpset:simpset ref etc. are
  2121 replaced by functions simpset:unit->simpset and
  2122 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2123 to patch your ML files accordingly;
  2124 
  2125 * HTML output now includes theory graph data for display with Java
  2126 applet or isatool browser; data generated automatically via isatool
  2127 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2128 
  2129 * defs may now be conditional; improved rewrite_goals_tac to handle
  2130 conditional equations;
  2131 
  2132 * defs now admits additional type arguments, using TYPE('a) syntax;
  2133 
  2134 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2135 creates a new theory node; implicit merge of thms' signatures is
  2136 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2137 transfer:theory->thm->thm in (rare) cases;
  2138 
  2139 * improved handling of draft signatures / theories; draft thms (and
  2140 ctyps, cterms) are automatically promoted to real ones;
  2141 
  2142 * slightly changed interfaces for oracles: admit many per theory, named
  2143 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2144 
  2145 * print_goals: optional output of const types (set show_consts and
  2146 show_types);
  2147 
  2148 * improved output of warnings (###) and errors (***);
  2149 
  2150 * subgoal_tac displays a warning if the new subgoal has type variables;
  2151 
  2152 * removed old README and Makefiles;
  2153 
  2154 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2155 
  2156 * removed obsolete init_pps and init_database;
  2157 
  2158 * deleted the obsolete tactical STATE, which was declared by
  2159     fun STATE tacfun st = tacfun st st;
  2160 
  2161 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2162 (which abbreviates $HOME);
  2163 
  2164 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2165 use isatool fixseq to adapt your ML programs (this works for fully
  2166 qualified references to the Sequence structure only!);
  2167 
  2168 * use_thy no longer requires writable current directory; it always
  2169 reloads .ML *and* .thy file, if either one is out of date;
  2170 
  2171 
  2172 *** Classical Reasoner ***
  2173 
  2174 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2175 tactics that use classical reasoning to simplify a subgoal without
  2176 splitting it into several subgoals;
  2177 
  2178 * Safe_tac: like safe_tac but uses the default claset;
  2179 
  2180 
  2181 *** Simplifier ***
  2182 
  2183 * added simplification meta rules:
  2184     (asm_)(full_)simplify: simpset -> thm -> thm;
  2185 
  2186 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2187 logics (again);
  2188 
  2189 * added prems argument to simplification procedures;
  2190 
  2191 * HOL, FOL, ZF: added infix function `addsplits':
  2192   instead of `<simpset> setloop (split_tac <thms>)'
  2193   you can simply write `<simpset> addsplits <thms>'
  2194 
  2195 
  2196 *** Syntax ***
  2197 
  2198 * TYPE('a) syntax for type reflection terms;
  2199 
  2200 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2201 
  2202 * pretty printer: changed order of mixfix annotation preference (again!);
  2203 
  2204 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2205 
  2206 
  2207 *** HOL ***
  2208 
  2209 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2210   with `addloop' of the simplifier to faciliate case splitting in premises.
  2211 
  2212 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2213 
  2214 * HOL/Auth: new protocol proofs including some for the Internet
  2215   protocol TLS;
  2216 
  2217 * HOL/Map: new theory of `maps' a la VDM;
  2218 
  2219 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2220 cancelling out common nat summands from =, <, <= (in)equalities, or
  2221 differences; simplification procedures nat_cancel_factor for
  2222 cancelling common factor from =, <, <= (in)equalities over natural
  2223 sums; nat_cancel contains both kinds of procedures, it is installed by
  2224 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2225 
  2226 * HOL/simplifier: terms of the form
  2227   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2228   are rewritten to
  2229   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2230   and those of the form
  2231   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2232   are rewritten to
  2233   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2234 
  2235 * HOL/datatype
  2236   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2237 
  2238   P(t_case f1 ... fn x) =
  2239      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2240         ...
  2241        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2242      )
  2243 
  2244   and a theorem `split_t_case_asm' of the form
  2245 
  2246   P(t_case f1 ... fn x) =
  2247     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2248         ...
  2249        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2250      )
  2251   which can be added to a simpset via `addsplits'. The existing theorems
  2252   expand_list_case and expand_option_case have been renamed to
  2253   split_list_case and split_option_case.
  2254 
  2255 * HOL/Arithmetic:
  2256   - `pred n' is automatically converted to `n-1'.
  2257     Users are strongly encouraged not to use `pred' any longer,
  2258     because it will disappear altogether at some point.
  2259   - Users are strongly encouraged to write "0 < n" rather than
  2260     "n ~= 0". Theorems and proof tools have been modified towards this
  2261     `standard'.
  2262 
  2263 * HOL/Lists:
  2264   the function "set_of_list" has been renamed "set" (and its theorems too);
  2265   the function "nth" now takes its arguments in the reverse order and
  2266   has acquired the infix notation "!" as in "xs!n".
  2267 
  2268 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2269 
  2270 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2271   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2272 
  2273 * HOL/record: extensible records with schematic structural subtyping
  2274 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2275 still lacks various theorems and concrete record syntax;
  2276 
  2277 
  2278 *** HOLCF ***
  2279 
  2280 * removed "axioms" and "generated by" sections;
  2281 
  2282 * replaced "ops" section by extended "consts" section, which is capable of
  2283   handling the continuous function space "->" directly;
  2284 
  2285 * domain package:
  2286   . proves theorems immediately and stores them in the theory,
  2287   . creates hierachical name space,
  2288   . now uses normal mixfix annotations (instead of cinfix...),
  2289   . minor changes to some names and values (for consistency),
  2290   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2291   . separator between mutual domain defs: changed "," to "and",
  2292   . improved handling of sort constraints;  now they have to
  2293     appear on the left-hand side of the equations only;
  2294 
  2295 * fixed LAM <x,y,zs>.b syntax;
  2296 
  2297 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2298 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2299 
  2300 
  2301 *** FOL and ZF ***
  2302 
  2303 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2304   with `addloop' of the simplifier to faciliate case splitting in premises.
  2305 
  2306 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2307 in HOL, they strip ALL and --> from proved theorems;
  2308 
  2309 
  2310 
  2311 New in Isabelle94-8 (May 1997)
  2312 ------------------------------
  2313 
  2314 *** General Changes ***
  2315 
  2316 * new utilities to build / run / maintain Isabelle etc. (in parts
  2317 still somewhat experimental); old Makefiles etc. still functional;
  2318 
  2319 * new 'Isabelle System Manual';
  2320 
  2321 * INSTALL text, together with ./configure and ./build scripts;
  2322 
  2323 * reimplemented type inference for greater efficiency, better error
  2324 messages and clean internal interface;
  2325 
  2326 * prlim command for dealing with lots of subgoals (an easier way of
  2327 setting goals_limit);
  2328 
  2329 
  2330 *** Syntax ***
  2331 
  2332 * supports alternative (named) syntax tables (parser and pretty
  2333 printer); internal interface is provided by add_modesyntax(_i);
  2334 
  2335 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2336 be used in conjunction with the Isabelle symbol font; uses the
  2337 "symbols" syntax table;
  2338 
  2339 * added token_translation interface (may translate name tokens in
  2340 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2341 the current print_mode); IMPORTANT: user print translation functions
  2342 are responsible for marking newly introduced bounds
  2343 (Syntax.mark_boundT);
  2344 
  2345 * token translations for modes "xterm" and "xterm_color" that display
  2346 names in bold, underline etc. or colors (which requires a color
  2347 version of xterm);
  2348 
  2349 * infixes may now be declared with names independent of their syntax;
  2350 
  2351 * added typed_print_translation (like print_translation, but may
  2352 access type of constant);
  2353 
  2354 
  2355 *** Classical Reasoner ***
  2356 
  2357 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2358 some limitations.  Blast_tac...
  2359   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2360   + ignores elimination rules that don't have the correct format
  2361         (the conclusion MUST be a formula variable)
  2362   + ignores types, which can make HOL proofs fail
  2363   + rules must not require higher-order unification, e.g. apply_type in ZF
  2364     [message "Function Var's argument not a bound variable" relates to this]
  2365   + its proof strategy is more general but can actually be slower
  2366 
  2367 * substitution with equality assumptions no longer permutes other
  2368 assumptions;
  2369 
  2370 * minor changes in semantics of addafter (now called addaltern); renamed
  2371 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2372 (and access functions for it);
  2373 
  2374 * improved combination of classical reasoner and simplifier:
  2375   + functions for handling clasimpsets
  2376   + improvement of addss: now the simplifier is called _after_ the
  2377     safe steps.
  2378   + safe variant of addss called addSss: uses safe simplifications
  2379     _during_ the safe steps. It is more complete as it allows multiple
  2380     instantiations of unknowns (e.g. with slow_tac).
  2381 
  2382 *** Simplifier ***
  2383 
  2384 * added interface for simplification procedures (functions that
  2385 produce *proven* rewrite rules on the fly, depending on current
  2386 redex);
  2387 
  2388 * ordering on terms as parameter (used for ordered rewriting);
  2389 
  2390 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2391 
  2392 * the solver is now split into a safe and an unsafe part.
  2393 This should be invisible for the normal user, except that the
  2394 functions setsolver and addsolver have been renamed to setSolver and
  2395 addSolver; added safe_asm_full_simp_tac;
  2396 
  2397 
  2398 *** HOL ***
  2399 
  2400 * a generic induction tactic `induct_tac' which works for all datatypes and
  2401 also for type `nat';
  2402 
  2403 * a generic case distinction tactic `exhaust_tac' which works for all
  2404 datatypes and also for type `nat';
  2405 
  2406 * each datatype comes with a function `size';
  2407 
  2408 * patterns in case expressions allow tuple patterns as arguments to
  2409 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2410 
  2411 * primrec now also works with type nat;
  2412 
  2413 * recdef: a new declaration form, allows general recursive functions to be
  2414 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2415 
  2416 * the constant for negation has been renamed from "not" to "Not" to
  2417 harmonize with FOL, ZF, LK, etc.;
  2418 
  2419 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2420 infinite lists;
  2421 
  2422 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2423 
  2424 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2425 problems in commutative rings, using axiomatic type classes for + and *;
  2426 
  2427 * more examples in HOL/MiniML and HOL/Auth;
  2428 
  2429 * more default rewrite rules for quantifiers, union/intersection;
  2430 
  2431 * a new constant `arbitrary == @x.False';
  2432 
  2433 * HOLCF/IOA replaces old HOL/IOA;
  2434 
  2435 * HOLCF changes: derived all rules and arities
  2436   + axiomatic type classes instead of classes
  2437   + typedef instead of faking type definitions
  2438   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2439   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2440   + eliminated the types void, one, tr
  2441   + use unit lift and bool lift (with translations) instead of one and tr
  2442   + eliminated blift from Lift3.thy (use Def instead of blift)
  2443   all eliminated rules are derived as theorems --> no visible changes ;
  2444 
  2445 
  2446 *** ZF ***
  2447 
  2448 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2449 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2450 as ZF_cs addSIs [equalityI];
  2451 
  2452 
  2453 
  2454 New in Isabelle94-7 (November 96)
  2455 ---------------------------------
  2456 
  2457 * allowing negative levels (as offsets) in prlev and choplev;
  2458 
  2459 * super-linear speedup for large simplifications;
  2460 
  2461 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2462 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2463 FAIL); can suppress it using the command Delsimps (ex_simps @
  2464 all_simps); De Morgan laws are also now included, by default;
  2465 
  2466 * improved printing of ==>  :  ~:
  2467 
  2468 * new object-logic "Sequents" adds linear logic, while replacing LK
  2469 and Modal (thanks to Sara Kalvala);
  2470 
  2471 * HOL/Auth: correctness proofs for authentication protocols;
  2472 
  2473 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2474 examples on HOL/Auth);
  2475 
  2476 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2477 the rewriter and classical reasoner simultaneously;
  2478 
  2479 * function uresult no longer returns theorems in "standard" format;
  2480 regain previous version by: val uresult = standard o uresult;
  2481 
  2482 
  2483 
  2484 New in Isabelle94-6
  2485 -------------------
  2486 
  2487 * oracles -- these establish an interface between Isabelle and trusted
  2488 external reasoners, which may deliver results as theorems;
  2489 
  2490 * proof objects (in particular record all uses of oracles);
  2491 
  2492 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2493 
  2494 * "constdefs" section in theory files;
  2495 
  2496 * "primrec" section (HOL) no longer requires names;
  2497 
  2498 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2499 
  2500 
  2501 
  2502 New in Isabelle94-5
  2503 -------------------
  2504 
  2505 * reduced space requirements;
  2506 
  2507 * automatic HTML generation from theories;
  2508 
  2509 * theory files no longer require "..." (quotes) around most types;
  2510 
  2511 * new examples, including two proofs of the Church-Rosser theorem;
  2512 
  2513 * non-curried (1994) version of HOL is no longer distributed;
  2514 
  2515 
  2516 
  2517 New in Isabelle94-4
  2518 -------------------
  2519 
  2520 * greatly reduced space requirements;
  2521 
  2522 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2523 
  2524 * searchable theorem database (see the section "Retrieving theorems" on
  2525 page 8 of the Reference Manual);
  2526 
  2527 * new examples, including Grabczewski's monumental case study of the
  2528 Axiom of Choice;
  2529 
  2530 * The previous version of HOL renamed to Old_HOL;
  2531 
  2532 * The new version of HOL (previously called CHOL) uses a curried syntax
  2533 for functions.  Application looks like f a b instead of f(a,b);
  2534 
  2535 * Mutually recursive inductive definitions finally work in HOL;
  2536 
  2537 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2538 translates to the operator "split";
  2539 
  2540 
  2541 
  2542 New in Isabelle94-3
  2543 -------------------
  2544 
  2545 * new infix operator, addss, allowing the classical reasoner to
  2546 perform simplification at each step of its search.  Example:
  2547         fast_tac (cs addss ss)
  2548 
  2549 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2550 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2551 look like (a,b) instead of <a,b>;
  2552 
  2553 * PLEASE NOTE: CHOL will eventually replace HOL!
  2554 
  2555 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2556 It translates to the operator "split".  A new theory of integers is available;
  2557 
  2558 * In ZF, integer numerals now denote two's-complement binary integers.
  2559 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2560 
  2561 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2562 of the Axiom of Choice;
  2563 
  2564 
  2565 
  2566 New in Isabelle94-2
  2567 -------------------
  2568 
  2569 * Significantly faster resolution;
  2570 
  2571 * the different sections in a .thy file can now be mixed and repeated
  2572 freely;
  2573 
  2574 * Database of theorems for FOL, HOL and ZF.  New
  2575 commands including qed, qed_goal and bind_thm store theorems in the database.
  2576 
  2577 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2578 a given theory (thms_of), or find out what theory a theorem was proved in
  2579 (theory_of_thm);
  2580 
  2581 * Bugs fixed in the inductive definition and datatype packages;
  2582 
  2583 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2584 and HOL_dup_cs obsolete;
  2585 
  2586 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2587 have been removed;
  2588 
  2589 * Simpler definition of function space in ZF;
  2590 
  2591 * new results about cardinal and ordinal arithmetic in ZF;
  2592 
  2593 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2594 types;
  2595 
  2596 
  2597 $Id$