NEWS
author kleing
Mon Apr 19 08:20:52 2004 +0200 (2004-04-19)
changeset 14624 9b3397a848c3
parent 14610 9c2e31e483b2
child 14655 8a95abf87dd3
permissions -rw-r--r--
add HOL4
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in Isabelle2004 (April 2004)
     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>), calligraphic (\<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   ProofGeneral and LaTeX, text between \<^bsup> and \<^esup> in
    33   superscript. The 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   may consist of any printable characters excluding the end bracket >.
    38 
    39 * Pure: Using new Isar command "finalconsts" (or the ML functions
    40   Theory.add_finals or Theory.add_finals_i) it is now possible to
    41   declare constants "final", which prevents their being given a definition
    42   later.  It is useful for constants whose behaviour is fixed axiomatically
    43   rather than definitionally, such as the meta-logic connectives.
    44 
    45 * Pure: 'instance' now handles general arities with general sorts
    46   (i.e. intersections of classes),
    47 
    48 * Presentation: generated HTML now uses a CSS style sheet to make layout
    49   (somewhat) independent of content. It is copied from lib/html/isabelle.css. 
    50   It can be changed to alter the colors/layout of generated pages.
    51 
    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" no longer interfere with
    72   current facts ("this"), admitting arbitrary combinations with "then"
    73   and derived forms.
    74 
    75 * Locales:
    76   - Goal statements involving the context element "includes" no longer
    77     generate theorems with internal delta predicates (those ending on
    78     "_axioms") in the premise.
    79     Resolve particular premise with <locale>.intro to obtain old form.
    80   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
    81     specification and "includes" elements in goal statement.
    82   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
    83     [intro?] and [elim?] (respectively) by default.
    84   - Experimental command for instantiation of locales in proof contexts:
    85         instantiate <label>[<attrs>]: <loc>
    86     Instantiates locale <loc> and adds all its theorems to the current context
    87     taking into account their attributes.  Label and attrs are optional
    88     modifiers, like in theorem declarations.  If present, names of
    89     instantiated theorems are qualified with <label>, and the attributes
    90     <attrs> are applied after any attributes these theorems might have already.
    91       If the locale has assumptions, a chained fact of the form
    92     "<loc> t1 ... tn" is expected from which instantiations of the parameters
    93     are derived.  The command does not support old-style locales declared
    94     with "locale (open)".
    95       A few (very simple) examples can be found in FOL/ex/LocaleInst.thy.
    96 
    97 * HOL: Tactic emulation methods induct_tac and case_tac understand static
    98   (Isar) contexts.
    99 
   100 
   101 *** HOL ***
   102 
   103 * Proof import: new image HOL4 contains the imported library from
   104   the HOL4 system with about 2500 theorems. It is imported by
   105   replaying proof terms produced by HOL4 in Isabelle. The HOL4 image
   106   can be used like any other Isabelle image.  See
   107   HOL/Import/HOL/README for more information.
   108 
   109 * Simplifier:
   110   - Much improved handling of linear and partial orders.
   111     Reasoners for linear and partial orders are set up for type classes
   112     "linorder" and "order" respectively, and are added to the default simpset
   113     as solvers.  This means that the simplifier can build transitivity chains
   114     to solve goals from the assumptions.
   115   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications
   116     of blast or auto after simplification become unnecessary because the goal
   117     is solved by simplification already.
   118 
   119 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws, 
   120     all proved in axiomatic type classes for semirings, rings and fields.
   121 
   122 * Numerics:
   123   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are
   124     now formalized using the Ring_and_Field theory mentioned above. 
   125   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently
   126     than before, because now they are set up once in a generic manner.
   127   - INCOMPATIBILITY: many type-specific arithmetic laws have gone. 
   128     Look for the general versions in Ring_and_Field (and Power if they concern
   129     exponentiation).
   130 
   131 * Type "rat" of the rational numbers is now available in HOL-Complex.
   132 
   133 * Records:
   134   - Record types are now by default printed with their type abbreviation
   135     instead of the list of all field types. This can be configured via
   136     the reference "print_record_type_abbr".
   137   - Simproc "record_upd_simproc" for simplification of multiple updates added 
   138     (not enabled by default).
   139   - Simproc "record_ex_sel_eq_simproc" to simplify EX x. sel r = x resp.
   140     EX x. x = sel r to True (not enabled by default).
   141   - Tactic "record_split_simp_tac" to split and simplify records added.
   142  
   143 * 'specification' command added, allowing for definition by
   144   specification.  There is also an 'ax_specification' command that
   145   introduces the new constants axiomatically.
   146 
   147 * arith(_tac) is now able to generate counterexamples for reals as well.
   148 
   149 * HOL-Algebra: new locale "ring" for non-commutative rings.
   150 
   151 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
   152   definitions, thanks to Sava Krsti\'{c} and John Matthews.
   153 
   154 * HOL-Matrix: a first theory for matrices in HOL with an application of 
   155   matrix theory to linear programming.
   156 
   157 * Unions and Intersections:
   158   The x-symbol output syntax of UN and INT has been changed
   159   from "\<Union>x \<in> A. B" to "\<Union\<^bsub>x \<in> A\<^esub> B"
   160   i.e. the index formulae has become a subscript, like in normal math.
   161   Similarly for "\<Union>x. B", and for \<Inter> instead of \<Union>.
   162   The subscript version is also accepted as input syntax.
   163 
   164 * Unions and Intersections over Intervals:
   165   There is new short syntax "UN i<=n. A" for "UN i:{0..n}. A". There is 
   166   also an x-symbol version with subscripts "\<Union>\<^bsub>i <= n\<^esub>. A" 
   167   like in normal math, and corresponding versions for < and for intersection.
   168 
   169 * ML: the legacy theory structures Int and List have been removed. They had
   170   conflicted with ML Basis Library structures having the same names.
   171 
   172 * 'refute' command added to search for (finite) countermodels.  Only works
   173   for a fragment of HOL.  The installation of an external SAT solver is
   174   highly recommended.  See "HOL/Refute.thy" for details.
   175 
   176 * 'quickcheck' command: Allows to find counterexamples by evaluating
   177   formulae under an assignment of free variables to random values.
   178   In contrast to 'refute', it can deal with inductive datatypes,
   179   but cannot handle quantifiers. See "HOL/ex/Quickcheck_Examples.thy"
   180   for examples.
   181 
   182 
   183 *** HOLCF ***
   184 
   185 * Streams now come with concatenation and are part of the HOLCF image
   186 
   187 
   188 
   189 New in Isabelle2003 (May 2003)
   190 ------------------------------
   191 
   192 *** General ***
   193 
   194 * Provers/simplifier:
   195 
   196   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   197     Assumptions are now subject to complete mutual simplification,
   198     not just from left to right. The simplifier now preserves
   199     the order of assumptions.
   200 
   201     Potential INCOMPATIBILITY:
   202 
   203     -- simp sometimes diverges where the old version did
   204        not, e.g. invoking simp on the goal
   205 
   206         [| P (f x); y = x; f x = f y |] ==> Q
   207 
   208        now gives rise to the infinite reduction sequence
   209 
   210         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   211 
   212        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   213        kind of problem.
   214 
   215     -- Tactics combining classical reasoner and simplification (such as auto)
   216        are also affected by this change, because many of them rely on
   217        simp. They may sometimes diverge as well or yield a different numbers
   218        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   219        in case of problems. Sometimes subsequent calls to the classical
   220        reasoner will fail because a preceeding call to the simplifier too
   221        eagerly simplified the goal, e.g. deleted redundant premises.
   222 
   223   - The simplifier trace now shows the names of the applied rewrite rules
   224 
   225   - You can limit the number of recursive invocations of the simplifier
   226     during conditional rewriting (where the simplifie tries to solve the
   227     conditions before applying the rewrite rule):
   228     ML "simp_depth_limit := n"
   229     where n is an integer. Thus you can force termination where previously
   230     the simplifier would diverge.
   231 
   232   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   233 
   234   - No longer aborts on failed congruence proof.  Instead, the
   235     congruence is ignored.
   236 
   237 * Pure: New generic framework for extracting programs from constructive
   238   proofs. See HOL/Extraction.thy for an example instantiation, as well
   239   as HOL/Extraction for some case studies.
   240 
   241 * Pure: The main goal of the proof state is no longer shown by default, only
   242 the subgoals. This behaviour is controlled by a new flag.
   243    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   244 (ML: Proof.show_main_goal).
   245 
   246 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   247 rules whose conclusion matches subgoal 1:
   248       PG menu: Isabelle/Isar -> Show me -> matching rules
   249 The rules are ordered by how closely they match the subgoal.
   250 In particular, rules that solve a subgoal outright are displayed first
   251 (or rather last, the way they are printed).
   252 (ML: ProofGeneral.print_intros())
   253 
   254 * Pure: New flag trace_unify_fail causes unification to print
   255 diagnostic information (PG: in trace buffer) when it fails. This is
   256 useful for figuring out why single step proofs like rule, erule or
   257 assumption failed.
   258 
   259 * Pure: Locale specifications now produce predicate definitions
   260 according to the body of text (covering assumptions modulo local
   261 definitions); predicate "loc_axioms" covers newly introduced text,
   262 while "loc" is cumulative wrt. all included locale expressions; the
   263 latter view is presented only on export into the global theory
   264 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   265 on the old view without predicates;
   266 
   267 * Pure: predefined locales "var" and "struct" are useful for sharing
   268 parameters (as in CASL, for example); just specify something like
   269 ``var x + var y + struct M'' as import;
   270 
   271 * Pure: improved thms_containing: proper indexing of facts instead of
   272 raw theorems; check validity of results wrt. current name space;
   273 include local facts of proof configuration (also covers active
   274 locales), cover fixed variables in index; may use "_" in term
   275 specification; an optional limit for the number of printed facts may
   276 be given (the default is 40);
   277 
   278 * Pure: disallow duplicate fact bindings within new-style theory files
   279 (batch-mode only);
   280 
   281 * Provers: improved induct method: assumptions introduced by case
   282 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   283 the goal statement); "foo" still refers to all facts collectively;
   284 
   285 * Provers: the function blast.overloaded has been removed: all constants
   286 are regarded as potentially overloaded, which improves robustness in exchange
   287 for slight decrease in efficiency;
   288 
   289 * Provers/linorder: New generic prover for transitivity reasoning over
   290 linear orders.  Note: this prover is not efficient!
   291 
   292 * Isar: preview of problems to finish 'show' now produce an error
   293 rather than just a warning (in interactive mode);
   294 
   295 
   296 *** HOL ***
   297 
   298 * arith(_tac)
   299 
   300  - Produces a counter example if it cannot prove a goal.
   301    Note that the counter example may be spurious if the goal is not a formula
   302    of quantifier-free linear arithmetic.
   303    In ProofGeneral the counter example appears in the trace buffer.
   304 
   305  - Knows about div k and mod k where k is a numeral of type nat or int.
   306 
   307  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   308    linear arithmetic fails. This takes account of quantifiers and divisibility.
   309    Presburger arithmetic can also be called explicitly via presburger(_tac). 
   310 
   311 * simp's arithmetic capabilities have been enhanced a bit: it now
   312 takes ~= in premises into account (by performing a case split);
   313 
   314 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   315 are distributed over a sum of terms;
   316 
   317 * New tactic "trans_tac" and method "trans" instantiate
   318 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   319 "<=", "<" and "="). 
   320 
   321 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main 
   322 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   323 
   324 * 'typedef' command has new option "open" to suppress the set
   325 definition;
   326 
   327 * functions Min and Max on finite sets have been introduced (theory
   328 Finite_Set);
   329 
   330 * attribute [symmetric] now works for relations as well; it turns
   331 (x,y) : R^-1 into (y,x) : R, and vice versa;
   332 
   333 * induct over a !!-quantified statement (say !!x1..xn):
   334   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   335 
   336 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   337 %x. None. Warning: empty_def now refers to the previously hidden definition
   338 of the empty set.
   339 
   340 * Algebra: formalization of classical algebra.  Intended as base for
   341 any algebraic development in Isabelle.  Currently covers group theory
   342 (up to Sylow's theorem) and ring theory (Universal Property of
   343 Univariate Polynomials).  Contributions welcome;
   344 
   345 * GroupTheory: deleted, since its material has been moved to Algebra;
   346 
   347 * Complex: new directory of the complex numbers with numeric constants, 
   348 nonstandard complex numbers, and some complex analysis, standard and 
   349 nonstandard (Jacques Fleuriot);
   350 
   351 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   352 
   353 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques 
   354 Fleuriot);
   355 
   356 * Real/HahnBanach: updated and adapted to locales;
   357 
   358 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   359 Gray and Kramer);
   360 
   361 * UNITY: added the Meier-Sanders theory of progress sets;
   362 
   363 * MicroJava: bytecode verifier and lightweight bytecode verifier
   364 as abstract algorithms, instantiated to the JVM;
   365 
   366 * Bali: Java source language formalization. Type system, operational
   367 semantics, axiomatic semantics. Supported language features:
   368 classes, interfaces, objects,virtual methods, static methods,
   369 static/instance fields, arrays, access modifiers, definite
   370 assignment, exceptions.
   371 
   372 
   373 *** ZF ***
   374 
   375 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   376 universe, etc.);
   377 
   378 * Main ZF: virtually all theories converted to new-style format;
   379 
   380 
   381 *** ML ***
   382 
   383 * Pure: Tactic.prove provides sane interface for internal proofs;
   384 omits the infamous "standard" operation, so this is more appropriate
   385 than prove_goalw_cterm in many situations (e.g. in simprocs);
   386 
   387 * Pure: improved error reporting of simprocs;
   388 
   389 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   390 up simprocs;
   391 
   392 
   393 *** Document preparation ***
   394 
   395 * uses \par instead of \\ for line breaks in theory text. This may
   396 shift some page breaks in large documents. To get the old behaviour
   397 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   398 
   399 * minimized dependencies of isabelle.sty and isabellesym.sty on 
   400 other packages
   401 
   402 * \<euro> now needs package babel/greek instead of marvosym (which
   403 broke \Rightarrow)
   404 
   405 * normal size for \<zero>...\<nine> (uses \mathbf instead of 
   406 textcomp package)
   407 
   408 
   409 
   410 New in Isabelle2002 (March 2002)
   411 --------------------------------
   412 
   413 *** Document preparation ***
   414 
   415 * greatly simplified document preparation setup, including more
   416 graceful interpretation of isatool usedir -i/-d/-D options, and more
   417 instructive isatool mkdir; users should basically be able to get
   418 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   419 users may run a separate document processing stage manually like this:
   420 "isatool usedir -D output HOL Test && isatool document Test/output";
   421 
   422 * theory dependency graph may now be incorporated into documents;
   423 isatool usedir -g true will produce session_graph.eps/.pdf for use
   424 with \includegraphics of LaTeX;
   425 
   426 * proper spacing of consecutive markup elements, especially text
   427 blocks after section headings;
   428 
   429 * support bold style (for single symbols only), input syntax is like
   430 this: "\<^bold>\<alpha>" or "\<^bold>A";
   431 
   432 * \<bullet> is now output as bold \cdot by default, which looks much
   433 better in printed text;
   434 
   435 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   436 note that these symbols are currently unavailable in Proof General /
   437 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   438 
   439 * isatool latex no longer depends on changed TEXINPUTS, instead
   440 isatool document copies the Isabelle style files to the target
   441 location;
   442 
   443 
   444 *** Isar ***
   445 
   446 * Pure/Provers: improved proof by cases and induction;
   447   - 'case' command admits impromptu naming of parameters (such as
   448     "case (Suc n)");
   449   - 'induct' method divinates rule instantiation from the inductive
   450     claim; no longer requires excessive ?P bindings for proper
   451     instantiation of cases;
   452   - 'induct' method properly enumerates all possibilities of set/type
   453     rules; as a consequence facts may be also passed through *type*
   454     rules without further ado;
   455   - 'induct' method now derives symbolic cases from the *rulified*
   456     rule (before it used to rulify cases stemming from the internal
   457     atomized version); this means that the context of a non-atomic
   458     statement becomes is included in the hypothesis, avoiding the
   459     slightly cumbersome show "PROP ?case" form;
   460   - 'induct' may now use elim-style induction rules without chaining
   461     facts, using ``missing'' premises from the goal state; this allows
   462     rules stemming from inductive sets to be applied in unstructured
   463     scripts, while still benefitting from proper handling of non-atomic
   464     statements; NB: major inductive premises need to be put first, all
   465     the rest of the goal is passed through the induction;
   466   - 'induct' proper support for mutual induction involving non-atomic
   467     rule statements (uses the new concept of simultaneous goals, see
   468     below);
   469   - append all possible rule selections, but only use the first
   470     success (no backtracking);
   471   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   472   - undeclared rule case names default to numbers 1, 2, 3, ...;
   473   - added 'print_induct_rules' (covered by help item in recent Proof
   474     General versions);
   475   - moved induct/cases attributes to Pure, methods to Provers;
   476   - generic method setup instantiated for FOL and HOL;
   477 
   478 * Pure: support multiple simultaneous goal statements, for example
   479 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   480 meta-level mechanism, this acts as if several individual goals had
   481 been stated separately; in particular common proof methods need to be
   482 repeated in order to cover all claims; note that a single elimination
   483 step is *not* sufficient to establish the two conjunctions, so this
   484 fails:
   485 
   486   assume "A & B" then have A and B ..   (*".." fails*)
   487 
   488 better use "obtain" in situations as above; alternative refer to
   489 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   490 
   491 * Pure: proper integration with ``locales''; unlike the original
   492 version by Florian Kammüller, Isar locales package high-level proof
   493 contexts rather than raw logical ones (e.g. we admit to include
   494 attributes everywhere); operations on locales include merge and
   495 rename; support for implicit arguments (``structures''); simultaneous
   496 type-inference over imports and text; see also HOL/ex/Locales.thy for
   497 some examples;
   498 
   499 * Pure: the following commands have been ``localized'', supporting a
   500 target locale specification "(in name)": 'lemma', 'theorem',
   501 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   502 stored both within the locale and at the theory level (exported and
   503 qualified by the locale name);
   504 
   505 * Pure: theory goals may now be specified in ``long'' form, with
   506 ad-hoc contexts consisting of arbitrary locale elements. for example
   507 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   508 definitions may be given, too); the result is a meta-level rule with
   509 the context elements being discharged in the obvious way;
   510 
   511 * Pure: new proof command 'using' allows to augment currently used
   512 facts after a goal statement ('using' is syntactically analogous to
   513 'apply', but acts on the goal's facts only); this allows chained facts
   514 to be separated into parts given before and after a claim, as in
   515 ``from a and b have C using d and e <proof>'';
   516 
   517 * Pure: renamed "antecedent" case to "rule_context";
   518 
   519 * Pure: new 'judgment' command records explicit information about the
   520 object-logic embedding (used by several tools internally); no longer
   521 use hard-wired "Trueprop";
   522 
   523 * Pure: added 'corollary' command;
   524 
   525 * Pure: fixed 'token_translation' command;
   526 
   527 * Pure: removed obsolete 'exported' attribute;
   528 
   529 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   530 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   531 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   532 
   533 * Pure: method 'atomize' presents local goal premises as object-level
   534 statements (atomic meta-level propositions); setup controlled via
   535 rewrite rules declarations of 'atomize' attribute; example
   536 application: 'induct' method with proper rule statements in improper
   537 proof *scripts*;
   538 
   539 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   540 now consider the syntactic context of assumptions, giving a better
   541 chance to get type-inference of the arguments right (this is
   542 especially important for locales);
   543 
   544 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   545 mode;
   546 
   547 * Pure/obtain: the formal conclusion "thesis", being marked as
   548 ``internal'', may no longer be reference directly in the text;
   549 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   550 situations;
   551 
   552 * Pure: generic 'sym' attribute which declares a rule both as pure
   553 'elim?' and for the 'symmetric' operation;
   554 
   555 * Pure: marginal comments ``--'' may now occur just anywhere in the
   556 text; the fixed correlation with particular command syntax has been
   557 discontinued;
   558 
   559 * Pure: new method 'rules' is particularly well-suited for proof
   560 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   561 but often produces more compact proof terms with less detours;
   562 
   563 * Pure/Provers/classical: simplified integration with pure rule
   564 attributes and methods; the classical "intro?/elim?/dest?"
   565 declarations coincide with the pure ones; the "rule" method no longer
   566 includes classically swapped intros; "intro" and "elim" methods no
   567 longer pick rules from the context; also got rid of ML declarations
   568 AddXIs/AddXEs/AddXDs; all of this has some potential for
   569 INCOMPATIBILITY;
   570 
   571 * Provers/classical: attribute 'swapped' produces classical inversions
   572 of introduction rules;
   573 
   574 * Provers/simplifier: 'simplified' attribute may refer to explicit
   575 rules instead of full simplifier context; 'iff' attribute handles
   576 conditional rules;
   577 
   578 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   579 
   580 * HOL: 'recdef' now fails on unfinished automated proofs, use
   581 "(permissive)" option to recover old behavior;
   582 
   583 * HOL: 'inductive' no longer features separate (collective) attributes
   584 for 'intros' (was found too confusing);
   585 
   586 * HOL: properly declared induction rules less_induct and
   587 wf_induct_rule;
   588 
   589 
   590 *** HOL ***
   591 
   592 * HOL: moved over to sane numeral syntax; the new policy is as
   593 follows:
   594 
   595   - 0 and 1 are polymorphic constants, which are defined on any
   596   numeric type (nat, int, real etc.);
   597 
   598   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   599   binary representation internally;
   600 
   601   - type nat has special constructor Suc, and generally prefers Suc 0
   602   over 1::nat and Suc (Suc 0) over 2::nat;
   603 
   604 This change may cause significant problems of INCOMPATIBILITY; here
   605 are some hints on converting existing sources:
   606 
   607   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   608   entities, so expressions involving "-" (unary or binary minus) need
   609   to be spaced properly;
   610 
   611   - existing occurrences of "1" may need to be constraint "1::nat" or
   612   even replaced by Suc 0; similar for old "2";
   613 
   614   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   615 
   616   - remove all special provisions on numerals in proofs;
   617 
   618 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   619 representation (depends on bin_arith_simps in the default context);
   620 
   621 * HOL: symbolic syntax for x^2 (numeral 2);
   622 
   623 * HOL: the class of all HOL types is now called "type" rather than
   624 "term"; INCOMPATIBILITY, need to adapt references to this type class
   625 in axclass/classes, instance/arities, and (usually rare) occurrences
   626 in typings (of consts etc.); internally the class is called
   627 "HOL.type", ML programs should refer to HOLogic.typeS;
   628 
   629 * HOL/record package improvements:
   630   - new derived operations "fields" to build a partial record section,
   631     "extend" to promote a fixed record to a record scheme, and
   632     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   633     declared as simp by default;
   634   - shared operations ("more", "fields", etc.) now need to be always
   635     qualified) --- potential INCOMPATIBILITY;
   636   - removed "make_scheme" operations (use "make" with "extend") --
   637     INCOMPATIBILITY;
   638   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   639   - provides cases/induct rules for use with corresponding Isar
   640     methods (for concrete records, record schemes, concrete more
   641     parts, and schematic more parts -- in that order);
   642   - internal definitions directly based on a light-weight abstract
   643     theory of product types over typedef rather than datatype;
   644 
   645 * HOL: generic code generator for generating executable ML code from
   646 specifications; specific support for HOL constructs such as inductive
   647 datatypes and sets, as well as recursive functions; can be invoked
   648 via 'generate_code' theory section;
   649 
   650 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   651 
   652 * HOL: consolidated and renamed several theories.  In particular:
   653 	Ord.thy has been absorbed into HOL.thy
   654 	String.thy has been absorbed into List.thy
   655  
   656 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   657 (beware of argument permutation!);
   658 
   659 * HOL: linorder_less_split superseded by linorder_cases;
   660 
   661 * HOL/List: "nodups" renamed to "distinct";
   662 
   663 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   664 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   665   - Ex_def has changed, now need to use some_eq_ex
   666 
   667 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   668 in this (rare) case use:
   669 
   670   delSWrapper "split_all_tac"
   671   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   672 
   673 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   674 MAY FAIL;
   675 
   676 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   677 Isabelle's type classes, ^ on functions and relations has too general
   678 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   679 necessary to attach explicit type constraints;
   680 
   681 * HOL/Relation: the prefix name of the infix "O" has been changed from
   682 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   683 renamed accordingly (eg "compI" -> "rel_compI").
   684 
   685 * HOL: syntax translations now work properly with numerals and records
   686 expressions;
   687 
   688 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   689 of "lam" -- INCOMPATIBILITY;
   690 
   691 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   692 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   693 renamed "Product_Type.unit";
   694 
   695 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   696 
   697 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   698 the "cases" method);
   699 
   700 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   701 Florian Kammüller);
   702 
   703 * HOL/IMP: updated and converted to new-style theory format; several
   704 parts turned into readable document, with proper Isar proof texts and
   705 some explanations (by Gerwin Klein);
   706 
   707 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   708 
   709 * HOL-Hyperreal is now a logic image;
   710 
   711 
   712 *** HOLCF ***
   713 
   714 * Isar: consts/constdefs supports mixfix syntax for continuous
   715 operations;
   716 
   717 * Isar: domain package adapted to new-style theory format, e.g. see
   718 HOLCF/ex/Dnat.thy;
   719 
   720 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   721 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   722 lift.induct_tac, always use UU instead of Undef;
   723 
   724 * HOLCF/IMP: updated and converted to new-style theory;
   725 
   726 
   727 *** ZF ***
   728 
   729 * Isar: proper integration of logic-specific tools and packages,
   730 including theory commands '(co)inductive', '(co)datatype',
   731 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   732 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   733 
   734 * theory Main no longer includes AC; for the Axiom of Choice, base
   735 your theory on Main_ZFC;
   736 
   737 * the integer library now covers quotients and remainders, with many
   738 laws relating division to addition, multiplication, etc.;
   739 
   740 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   741 typeless version of the formalism;
   742 
   743 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   744 format;
   745 
   746 * ZF/Induct: new directory for examples of inductive definitions,
   747 including theory Multiset for multiset orderings; converted to
   748 new-style theory format;
   749 
   750 * ZF: many new theorems about lists, ordinals, etc.;
   751 
   752 
   753 *** General ***
   754 
   755 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   756 variable proof controls level of detail: 0 = no proofs (only oracle
   757 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   758 also ref manual for further ML interfaces;
   759 
   760 * Pure/axclass: removed obsolete ML interface
   761 goal_subclass/goal_arity;
   762 
   763 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   764 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   765 separate tokens, so expressions involving minus need to be spaced
   766 properly;
   767 
   768 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   769 rather than "infixl" or "infixr";
   770 
   771 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   772 sort constraint specifications in type inference; e.g. "x::_::foo"
   773 ensures that the type of "x" is of sort "foo" (but not necessarily a
   774 type variable);
   775 
   776 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   777 control output of nested => (types); the default behavior is
   778 "type_brackets";
   779 
   780 * Pure/syntax: builtin parse translation for "_constify" turns valued
   781 tokens into AST constants;
   782 
   783 * Pure/syntax: prefer later declarations of translations and print
   784 translation functions; potential INCOMPATIBILITY: need to reverse
   785 multiple declarations for same syntax element constant;
   786 
   787 * Pure/show_hyps reset by default (in accordance to existing Isar
   788 practice);
   789 
   790 * Provers/classical: renamed addaltern to addafter, addSaltern to
   791 addSafter;
   792 
   793 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   794 as well;
   795 
   796 * system: tested support for MacOS X; should be able to get Isabelle +
   797 Proof General to work in a plain Terminal after installing Poly/ML
   798 (e.g. from the Isabelle distribution area) and GNU bash alone
   799 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   800 support requires further installations, e.g. from
   801 http://fink.sourceforge.net/);
   802 
   803 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   804 
   805 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   806 of 40 MB), cf. ML_OPTIONS;
   807 
   808 * system: Proof General keywords specification is now part of the
   809 Isabelle distribution (see etc/isar-keywords.el);
   810 
   811 * system: support for persistent Proof General sessions (refrain from
   812 outdating all loaded theories on startup); user may create writable
   813 logic images like this: ``isabelle -q HOL Test'';
   814 
   815 * system: smart selection of Isabelle process versus Isabelle
   816 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   817 run both "isabelle" and "Isabelle" even if file names are badly
   818 damaged (executable inspects the case of the first letter of its own
   819 name); added separate "isabelle-process" and "isabelle-interface";
   820 
   821 * system: refrain from any attempt at filtering input streams; no
   822 longer support ``8bit'' encoding of old isabelle font, instead proper
   823 iso-latin characters may now be used; the related isatools
   824 "symbolinput" and "nonascii" have disappeared as well;
   825 
   826 * system: removed old "xterm" interface (the print modes "xterm" and
   827 "xterm_color" are still available for direct use in a suitable
   828 terminal);
   829 
   830 
   831 
   832 New in Isabelle99-2 (February 2001)
   833 -----------------------------------
   834 
   835 *** Overview of INCOMPATIBILITIES ***
   836 
   837 * HOL: please note that theories in the Library and elsewhere often use the
   838 new-style (Isar) format; to refer to their theorems in an ML script you must
   839 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   840 
   841 * HOL: inductive package no longer splits induction rule aggressively,
   842 but only as far as specified by the introductions given; the old
   843 format may be recovered via ML function complete_split_rule or attribute
   844 'split_rule (complete)';
   845 
   846 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   847 gfp_Tarski to gfp_unfold;
   848 
   849 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   850 
   851 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   852 relation); infix "^^" has been renamed "``"; infix "``" has been
   853 renamed "`"; "univalent" has been renamed "single_valued";
   854 
   855 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   856 operation;
   857 
   858 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   859 
   860 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   861 
   862 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   863 consequence, it is no longer monotonic wrt. the local goal context
   864 (which is now passed through the inductive cases);
   865 
   866 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   867 \<gg> to \<ggreater>;
   868 
   869 
   870 *** Document preparation ***
   871 
   872 * \isabellestyle{NAME} selects version of Isabelle output (currently
   873 available: are "it" for near math-mode best-style output, "sl" for
   874 slanted text style, and "tt" for plain type-writer; if no
   875 \isabellestyle command is given, output is according to slanted
   876 type-writer);
   877 
   878 * support sub/super scripts (for single symbols only), input syntax is
   879 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   880 
   881 * some more standard symbols; see Appendix A of the system manual for
   882 the complete list of symbols defined in isabellesym.sty;
   883 
   884 * improved isabelle style files; more abstract symbol implementation
   885 (should now use \isamath{...} and \isatext{...} in custom symbol
   886 definitions);
   887 
   888 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   889 state; Note that presentation of goal states does not conform to
   890 actual human-readable proof documents.  Please do not include goal
   891 states into document output unless you really know what you are doing!
   892 
   893 * proper indentation of antiquoted output with proportional LaTeX
   894 fonts;
   895 
   896 * no_document ML operator temporarily disables LaTeX document
   897 generation;
   898 
   899 * isatool unsymbolize tunes sources for plain ASCII communication;
   900 
   901 
   902 *** Isar ***
   903 
   904 * Pure: Isar now suffers initial goal statements to contain unbound
   905 schematic variables (this does not conform to actual readable proof
   906 documents, due to unpredictable outcome and non-compositional proof
   907 checking); users who know what they are doing may use schematic goals
   908 for Prolog-style synthesis of proven results;
   909 
   910 * Pure: assumption method (an implicit finishing) now handles actual
   911 rules as well;
   912 
   913 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
   914 initial goal, declare "that" only as Pure intro (only for single
   915 steps); the "that" rule assumption may now be involved in implicit
   916 finishing, thus ".." becomes a feasible for trivial obtains;
   917 
   918 * Pure: default proof step now includes 'intro_classes'; thus trivial
   919 instance proofs may be performed by "..";
   920 
   921 * Pure: ?thesis / ?this / "..." now work for pure meta-level
   922 statements as well;
   923 
   924 * Pure: more robust selection of calculational rules;
   925 
   926 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
   927 rule (as well as the assumption rule);
   928 
   929 * Pure: 'thm_deps' command visualizes dependencies of theorems and
   930 lemmas, using the graph browser tool;
   931 
   932 * Pure: predict failure of "show" in interactive mode;
   933 
   934 * Pure: 'thms_containing' now takes actual terms as arguments;
   935 
   936 * HOL: improved method 'induct' --- now handles non-atomic goals
   937 (potential INCOMPATIBILITY); tuned error handling;
   938 
   939 * HOL: cases and induct rules now provide explicit hints about the
   940 number of facts to be consumed (0 for "type" and 1 for "set" rules);
   941 any remaining facts are inserted into the goal verbatim;
   942 
   943 * HOL: local contexts (aka cases) may now contain term bindings as
   944 well; the 'cases' and 'induct' methods new provide a ?case binding for
   945 the result to be shown in each case;
   946 
   947 * HOL: added 'recdef_tc' command;
   948 
   949 * isatool convert assists in eliminating legacy ML scripts;
   950 
   951 
   952 *** HOL ***
   953 
   954 * HOL/Library: a collection of generic theories to be used together
   955 with main HOL; the theory loader path already includes this directory
   956 by default; the following existing theories have been moved here:
   957 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
   958 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
   959 
   960 * HOL/Unix: "Some aspects of Unix file-system security", a typical
   961 modelling and verification task performed in Isabelle/HOL +
   962 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
   963 
   964 * HOL/Algebra: special summation operator SUM no longer exists, it has
   965 been replaced by setsum; infix 'assoc' now has priority 50 (like
   966 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
   967 'domain', this makes the theory consistent with mathematical
   968 literature;
   969 
   970 * HOL basics: added overloaded operations "inverse" and "divide"
   971 (infix "/"), syntax for generic "abs" operation, generic summation
   972 operator \<Sum>;
   973 
   974 * HOL/typedef: simplified package, provide more useful rules (see also
   975 HOL/subset.thy);
   976 
   977 * HOL/datatype: induction rule for arbitrarily branching datatypes is
   978 now expressed as a proper nested rule (old-style tactic scripts may
   979 require atomize_strip_tac to cope with non-atomic premises);
   980 
   981 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
   982 to "split_conv" (old name still available for compatibility);
   983 
   984 * HOL: improved concrete syntax for strings (e.g. allows translation
   985 rules with string literals);
   986 
   987 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
   988  and Fleuriot's mechanization of analysis, including the transcendental
   989  functions for the reals;
   990 
   991 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
   992 
   993 
   994 *** CTT ***
   995 
   996 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
   997 "lam" is displayed as TWO lambda-symbols
   998 
   999 * CTT: theory Main now available, containing everything (that is, Bool
  1000 and Arith);
  1001 
  1002 
  1003 *** General ***
  1004 
  1005 * Pure: the Simplifier has been implemented properly as a derived rule
  1006 outside of the actual kernel (at last!); the overall performance
  1007 penalty in practical applications is about 50%, while reliability of
  1008 the Isabelle inference kernel has been greatly improved;
  1009 
  1010 * print modes "brackets" and "no_brackets" control output of nested =>
  1011 (types) and ==> (props); the default behaviour is "brackets";
  1012 
  1013 * Provers: fast_tac (and friends) now handle actual object-logic rules
  1014 as assumptions as well;
  1015 
  1016 * system: support Poly/ML 4.0;
  1017 
  1018 * system: isatool install handles KDE version 1 or 2;
  1019 
  1020 
  1021 
  1022 New in Isabelle99-1 (October 2000)
  1023 ----------------------------------
  1024 
  1025 *** Overview of INCOMPATIBILITIES ***
  1026 
  1027 * HOL: simplification of natural numbers is much changed; to partly
  1028 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
  1029 issue the following ML commands:
  1030 
  1031   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
  1032   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
  1033 
  1034 * HOL: simplification no longer dives into case-expressions; this is
  1035 controlled by "t.weak_case_cong" for each datatype t;
  1036 
  1037 * HOL: nat_less_induct renamed to less_induct;
  1038 
  1039 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
  1040 fixsome to patch .thy and .ML sources automatically;
  1041 
  1042   select_equality  -> some_equality
  1043   select_eq_Ex     -> some_eq_ex
  1044   selectI2EX       -> someI2_ex
  1045   selectI2         -> someI2
  1046   selectI          -> someI
  1047   select1_equality -> some1_equality
  1048   Eps_sym_eq       -> some_sym_eq_trivial
  1049   Eps_eq           -> some_eq_trivial
  1050 
  1051 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
  1052 
  1053 * HOL: removed obsolete theorem binding expand_if (refer to split_if
  1054 instead);
  1055 
  1056 * HOL: the recursion equations generated by 'recdef' are now called
  1057 f.simps instead of f.rules;
  1058 
  1059 * HOL: qed_spec_mp now also handles bounded ALL as well;
  1060 
  1061 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  1062 sometimes be needed;
  1063 
  1064 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  1065 
  1066 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  1067 
  1068 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  1069 product is now "<*>" instead of "Times"; the lexicographic product is
  1070 now "<*lex*>" instead of "**";
  1071 
  1072 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  1073 of main HOL, but was unused); better use HOL's datatype package;
  1074 
  1075 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  1076 the old syntax may be recovered as follows:
  1077 
  1078   syntax (symbols)
  1079     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  1080       (infixl "\\<oplus>" 100)
  1081 
  1082 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1083 
  1084 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1085 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1086 internally;
  1087 
  1088 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1089 changed from A/r to A//r;
  1090 
  1091 * ZF: new treatment of arithmetic (nat & int) may break some old
  1092 proofs;
  1093 
  1094 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1095 rulify -> rule_format, elimify -> elim_format, ...);
  1096 
  1097 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1098 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1099 should have to change intro!! to intro? only); replaced "delrule" by
  1100 "rule del";
  1101 
  1102 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1103 
  1104 * Provers: strengthened force_tac by using new first_best_tac;
  1105 
  1106 * LaTeX document preparation: several changes of isabelle.sty (see
  1107 lib/texinputs);
  1108 
  1109 
  1110 *** Document preparation ***
  1111 
  1112 * formal comments (text blocks etc.) in new-style theories may now
  1113 contain antiquotations of thm/prop/term/typ/text to be presented
  1114 according to latex print mode; concrete syntax is like this:
  1115 @{term[show_types] "f(x) = a + x"};
  1116 
  1117 * isatool mkdir provides easy setup of Isabelle session directories,
  1118 including proper document sources;
  1119 
  1120 * generated LaTeX sources are now deleted after successful run
  1121 (isatool document -c); may retain a copy somewhere else via -D option
  1122 of isatool usedir;
  1123 
  1124 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1125 style files, achieving self-contained LaTeX sources and simplifying
  1126 LaTeX debugging;
  1127 
  1128 * old-style theories now produce (crude) LaTeX output as well;
  1129 
  1130 * browser info session directories are now self-contained (may be put
  1131 on WWW server seperately); improved graphs of nested sessions; removed
  1132 graph for 'all sessions';
  1133 
  1134 * several improvements in isabelle style files; \isabellestyle{it}
  1135 produces fake math mode output; \isamarkupheader is now \section by
  1136 default; see lib/texinputs/isabelle.sty etc.;
  1137 
  1138 
  1139 *** Isar ***
  1140 
  1141 * Isar/Pure: local results and corresponding term bindings are now
  1142 subject to Hindley-Milner polymorphism (similar to ML); this
  1143 accommodates incremental type-inference very nicely;
  1144 
  1145 * Isar/Pure: new derived language element 'obtain' supports
  1146 generalized existence reasoning;
  1147 
  1148 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1149 support accumulation of results, without applying any rules yet;
  1150 useful to collect intermediate results without explicit name
  1151 references, and for use with transitivity rules with more than 2
  1152 premises;
  1153 
  1154 * Isar/Pure: scalable support for case-analysis type proofs: new
  1155 'case' language element refers to local contexts symbolically, as
  1156 produced by certain proof methods; internally, case names are attached
  1157 to theorems as "tags";
  1158 
  1159 * Isar/Pure: theory command 'hide' removes declarations from
  1160 class/type/const name spaces;
  1161 
  1162 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1163 indicate potential overloading;
  1164 
  1165 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1166 
  1167 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1168 "{a,b,c}" instead of {a,b,c};
  1169 
  1170 * Isar/Pure now provides its own version of intro/elim/dest
  1171 attributes; useful for building new logics, but beware of confusion
  1172 with the version in Provers/classical;
  1173 
  1174 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1175 case name 'antecedent';
  1176 
  1177 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1178 to the current context is now done automatically);
  1179 
  1180 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1181 for definining proof methods in ML;
  1182 
  1183 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1184 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1185 most cases, one should have to change intro!! to intro? only);
  1186 replaced "delrule" by "rule del";
  1187 
  1188 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1189 'symmetric' attribute (the latter supercedes [RS sym]);
  1190 
  1191 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1192 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1193 well (including splits);
  1194 
  1195 * Isar/Provers: Simplifier and Classical methods now support all kind
  1196 of modifiers used in the past, including 'cong', 'iff', etc.
  1197 
  1198 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1199 of Simplifier and Classical reasoner);
  1200 
  1201 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1202 now support named cases; major packages (inductive, datatype, primrec,
  1203 recdef) support case names and properly name parameters;
  1204 
  1205 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1206 monotonicity conditions are extracted to be proven at end of
  1207 calculations;
  1208 
  1209 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1210 method anyway;
  1211 
  1212 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1213 split_if split_if_asm; datatype package provides theorems foo.splits =
  1214 foo.split foo.split_asm for each datatype;
  1215 
  1216 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1217 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1218 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1219 use "(cases (simplified))" method in proper proof texts);
  1220 
  1221 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1222 
  1223 * Isar: names of theorems etc. may be natural numbers as well;
  1224 
  1225 * Isar: 'pr' command: optional arguments for goals_limit and
  1226 ProofContext.prems_limit; no longer prints theory contexts, but only
  1227 proof states;
  1228 
  1229 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1230 additional print modes to be specified; e.g. "pr(latex)" will print
  1231 proof state according to the Isabelle LaTeX style;
  1232 
  1233 * Isar: improved support for emulating tactic scripts, including proof
  1234 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1235 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1236 (for HOL datatypes);
  1237 
  1238 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1239 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1240 'proof method scripts' have to be in depth-first order;
  1241 
  1242 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1243 
  1244 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1245 should instead use individual commands for printing items
  1246 (print_commands, print_methods etc.);
  1247 
  1248 * Isar: added 'nothing' --- the empty list of theorems;
  1249 
  1250 
  1251 *** HOL ***
  1252 
  1253 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1254 corresponding virtual machine and a specification of its bytecode
  1255 verifier and a lightweight bytecode verifier, including proofs of
  1256 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1257 Cornelia Pusch (see also the homepage of project Bali at
  1258 http://isabelle.in.tum.de/Bali/);
  1259 
  1260 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1261 Clemens Ballarin;
  1262 
  1263 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1264 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1265 Rasmussen;
  1266 
  1267 * HOL/Lattice: fundamental concepts of lattice theory and order
  1268 structures, including duals, properties of bounds versus algebraic
  1269 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1270 Theorem for complete lattices etc.; may also serve as a demonstration
  1271 for abstract algebraic reasoning using axiomatic type classes, and
  1272 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1273 
  1274 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1275 von Oheimb;
  1276 
  1277 * HOL/IMPP: extension of IMP with local variables and mutually
  1278 recursive procedures, by David von Oheimb;
  1279 
  1280 * HOL/Lambda: converted into new-style theory and document;
  1281 
  1282 * HOL/ex/Multiquote: example of multiple nested quotations and
  1283 anti-quotations -- basically a generalized version of de-Bruijn
  1284 representation; very useful in avoiding lifting of operations;
  1285 
  1286 * HOL/record: added general record equality rule to simpset; fixed
  1287 select-update simplification procedure to handle extended records as
  1288 well; admit "r" as field name;
  1289 
  1290 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1291 other numeric types and also as the identity of groups, rings, etc.;
  1292 
  1293 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1294 Types nat and int belong to this axclass;
  1295 
  1296 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1297    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1298    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1299   two terms #m*u and #n*u are replaced by #(m+n)*u
  1300     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1301   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1302     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1303 
  1304 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1305 powerful prover for predicate logic but knows nothing of clasets; see
  1306 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1307 
  1308 * HOL: new version of "case_tac" subsumes both boolean case split and
  1309 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1310 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1311 
  1312 * HOL: simplification no longer dives into case-expressions: only the
  1313 selector expression is simplified, but not the remaining arms; to
  1314 enable full simplification of case-expressions for datatype t, you may
  1315 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1316 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1317 
  1318 * HOL/recdef: the recursion equations generated by 'recdef' for
  1319 function 'f' are now called f.simps instead of f.rules; if all
  1320 termination conditions are proved automatically, these simplification
  1321 rules are added to the simpset, as in primrec; rules may be named
  1322 individually as well, resulting in a separate list of theorems for
  1323 each equation;
  1324 
  1325 * HOL/While is a new theory that provides a while-combinator. It
  1326 permits the definition of tail-recursive functions without the
  1327 provision of a termination measure. The latter is necessary once the
  1328 invariant proof rule for while is applied.
  1329 
  1330 * HOL: new (overloaded) notation for the set of elements below/above
  1331 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1332 
  1333 * HOL: theorems impI, allI, ballI bound as "strip";
  1334 
  1335 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1336 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1337 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1338 
  1339 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1340 
  1341 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1342 main HOL, but was unused);
  1343 
  1344 * HOL: fewer consts declared as global (e.g. have to refer to
  1345 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1346 
  1347 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1348 in case of overlap with user translations (e.g. judgements over
  1349 tuples); (note that the underlying logical represenation is still
  1350 bogus);
  1351 
  1352 
  1353 *** ZF ***
  1354 
  1355 * ZF: simplification automatically cancels common terms in arithmetic
  1356 expressions over nat and int;
  1357 
  1358 * ZF: new treatment of nat to minimize type-checking: all operators
  1359 coerce their operands to a natural number using the function natify,
  1360 making the algebraic laws unconditional;
  1361 
  1362 * ZF: as above, for int: operators coerce their operands to an integer
  1363 using the function intify;
  1364 
  1365 * ZF: the integer library now contains many of the usual laws for the
  1366 orderings, including $<=, and monotonicity laws for $+ and $*;
  1367 
  1368 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1369 simplification;
  1370 
  1371 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1372 to the simplifier and classical reasoner simultaneously;
  1373 
  1374 
  1375 *** General ***
  1376 
  1377 * Provers: blast_tac now handles actual object-logic rules as
  1378 assumptions; note that auto_tac uses blast_tac internally as well;
  1379 
  1380 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1381 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1382 
  1383 * Provers: delrules now handles destruct rules as well (no longer need
  1384 explicit make_elim);
  1385 
  1386 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1387   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1388 use instead the strong form,
  1389   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1390 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1391 from destruct-rules;
  1392 
  1393 * Provers: Simplifier.easy_setup provides a fast path to basic
  1394 Simplifier setup for new object-logics;
  1395 
  1396 * Pure: AST translation rules no longer require constant head on LHS;
  1397 
  1398 * Pure: improved name spaces: ambiguous output is qualified; support
  1399 for hiding of names;
  1400 
  1401 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1402 XSYMBOL_HOME; no longer need to do manual configuration in most
  1403 situations;
  1404 
  1405 * system: compression of ML heaps images may now be controlled via -c
  1406 option of isabelle and isatool usedir (currently only observed by
  1407 Poly/ML);
  1408 
  1409 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1410 useful for remote X11);
  1411 
  1412 * system: provide TAGS file for Isabelle sources;
  1413 
  1414 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1415 order;
  1416 
  1417 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1418 timing flag supersedes proof_timing and Toplevel.trace;
  1419 
  1420 * ML: new combinators |>> and |>>> for incremental transformations
  1421 with secondary results (e.g. certain theory extensions):
  1422 
  1423 * ML: PureThy.add_defs gets additional argument to indicate potential
  1424 overloading (usually false);
  1425 
  1426 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1427 results;
  1428 
  1429 
  1430 
  1431 New in Isabelle99 (October 1999)
  1432 --------------------------------
  1433 
  1434 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1435 
  1436 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1437 are no longer simplified.  (This allows the simplifier to unfold recursive
  1438 functional programs.)  To restore the old behaviour, declare
  1439 
  1440     Delcongs [if_weak_cong];
  1441 
  1442 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1443 complement;
  1444 
  1445 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1446 
  1447 * HOL/datatype: mutual_induct_tac no longer exists --
  1448   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1449 
  1450 * HOL/typedef: fixed type inference for representing set; type
  1451 arguments now have to occur explicitly on the rhs as type constraints;
  1452 
  1453 * ZF: The con_defs part of an inductive definition may no longer refer
  1454 to constants declared in the same theory;
  1455 
  1456 * HOL, ZF: the function mk_cases, generated by the inductive
  1457 definition package, has lost an argument.  To simplify its result, it
  1458 uses the default simpset instead of a supplied list of theorems.
  1459 
  1460 * HOL/List: the constructors of type list are now Nil and Cons;
  1461 
  1462 * Simplifier: the type of the infix ML functions
  1463         setSSolver addSSolver setSolver addSolver
  1464 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1465 for packaging solvers. A solver is created via
  1466         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1467 where the string argument is only a comment.
  1468 
  1469 
  1470 *** Proof tools ***
  1471 
  1472 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1473 decision procedure for linear arithmetic. Currently it is used for
  1474 types `nat', `int', and `real' in HOL (see below); it can, should and
  1475 will be instantiated for other types and logics as well.
  1476 
  1477 * The simplifier now accepts rewrite rules with flexible heads, eg
  1478      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1479   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1480   matching.
  1481 
  1482 
  1483 *** General ***
  1484 
  1485 * New Isabelle/Isar subsystem provides an alternative to traditional
  1486 tactical theorem proving; together with the ProofGeneral/isar user
  1487 interface it offers an interactive environment for developing human
  1488 readable proof documents (Isar == Intelligible semi-automated
  1489 reasoning); for further information see isatool doc isar-ref,
  1490 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1491 
  1492 * improved and simplified presentation of theories: better HTML markup
  1493 (including colors), graph views in several sizes; isatool usedir now
  1494 provides a proper interface for user theories (via -P option); actual
  1495 document preparation based on (PDF)LaTeX is available as well (for
  1496 new-style theories only); see isatool doc system for more information;
  1497 
  1498 * native support for Proof General, both for classic Isabelle and
  1499 Isabelle/Isar;
  1500 
  1501 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1502 using the graph browser tool;
  1503 
  1504 * Isabelle manuals now also available as PDF;
  1505 
  1506 * theory loader rewritten from scratch (may not be fully
  1507 bug-compatible); old loadpath variable has been replaced by show_path,
  1508 add_path, del_path, reset_path functions; new operations such as
  1509 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1510 isatool doc ref);
  1511 
  1512 * improved isatool install: option -k creates KDE application icon,
  1513 option -p DIR installs standalone binaries;
  1514 
  1515 * added ML_PLATFORM setting (useful for cross-platform installations);
  1516 more robust handling of platform specific ML images for SML/NJ;
  1517 
  1518 * the settings environment is now statically scoped, i.e. it is never
  1519 created again in sub-processes invoked from isabelle, isatool, or
  1520 Isabelle;
  1521 
  1522 * path element specification '~~' refers to '$ISABELLE_HOME';
  1523 
  1524 * in locales, the "assumes" and "defines" parts may be omitted if
  1525 empty;
  1526 
  1527 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1528 long arrows);
  1529 
  1530 * new print_mode "HTML";
  1531 
  1532 * new flag show_tags controls display of tags of theorems (which are
  1533 basically just comments that may be attached by some tools);
  1534 
  1535 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1536 mode and goal output format:
  1537 
  1538 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1539 244c244
  1540 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1541 ---
  1542 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1543 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1544 181c181
  1545 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1546 ---
  1547 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1548 
  1549 * function bind_thms stores lists of theorems (cf. bind_thm);
  1550 
  1551 * new shorthand tactics ftac, eatac, datac, fatac;
  1552 
  1553 * qed (and friends) now accept "" as result name; in that case the
  1554 theorem is not stored, but proper checks and presentation of the
  1555 result still apply;
  1556 
  1557 * theorem database now also indexes constants "Trueprop", "all",
  1558 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1559 
  1560 
  1561 *** HOL ***
  1562 
  1563 ** HOL arithmetic **
  1564 
  1565 * There are now decision procedures for linear arithmetic over nat and
  1566 int:
  1567 
  1568 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1569 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1570 are treated as atomic; subformulae not involving type `nat' or `int'
  1571 are ignored; quantified subformulae are ignored unless they are
  1572 positive universal or negative existential. The tactic has to be
  1573 invoked by hand and can be a little bit slow. In particular, the
  1574 running time is exponential in the number of occurrences of `min' and
  1575 `max', and `-' on `nat'.
  1576 
  1577 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1578 (negated) (in)equalities among the premises and the conclusion into
  1579 account (i.e. no compound formulae) and does not know about `min' and
  1580 `max', and `-' on `nat'. It is fast and is used automatically by the
  1581 simplifier.
  1582 
  1583 NB: At the moment, these decision procedures do not cope with mixed
  1584 nat/int formulae where the two parts interact, such as `m < n ==>
  1585 int(m) < int(n)'.
  1586 
  1587 * HOL/Numeral provides a generic theory of numerals (encoded
  1588 efficiently as bit strings); setup for types nat/int/real is in place;
  1589 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1590 int, existing theories and proof scripts may require a few additional
  1591 type constraints;
  1592 
  1593 * integer division and remainder can now be performed on constant
  1594 arguments;
  1595 
  1596 * many properties of integer multiplication, division and remainder
  1597 are now available;
  1598 
  1599 * An interface to the Stanford Validity Checker (SVC) is available through the
  1600 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1601 are proved automatically.  SVC must be installed separately, and its results
  1602 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1603 invocation of the underlying oracle).  For SVC see
  1604   http://verify.stanford.edu/SVC
  1605 
  1606 * IsaMakefile: the HOL-Real target now builds an actual image;
  1607 
  1608 
  1609 ** HOL misc **
  1610 
  1611 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1612 (in Isabelle/Isar) -- by Gertrud Bauer;
  1613 
  1614 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1615 analysis for assembly languages with subtypes;
  1616 
  1617 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1618 -- avoids syntactic ambiguities and treats state, transition, and
  1619 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1620 changed syntax and (many) tactics;
  1621 
  1622 * HOL/inductive: Now also handles more general introduction rules such
  1623   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1624   theorems are now maintained within the theory (maintained via the
  1625   "mono" attribute);
  1626 
  1627 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1628   (using function types) such as
  1629 
  1630   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1631 
  1632 * HOL/record: record_simproc (part of the default simpset) takes care
  1633 of selectors applied to updated records; record_split_tac is no longer
  1634 part of the default claset; update_defs may now be removed from the
  1635 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1636 
  1637   claset_ref () := claset() addSWrapper record_split_wrapper;
  1638   Delsimprocs [record_simproc]
  1639 
  1640 * HOL/typedef: fixed type inference for representing set; type
  1641 arguments now have to occur explicitly on the rhs as type constraints;
  1642 
  1643 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1644 names rather than an ML expression;
  1645 
  1646 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1647 supplied later.  Program schemes can be defined, such as
  1648     "While B C s = (if B s then While B C (C s) else s)"
  1649 where the well-founded relation can be chosen after B and C have been given.
  1650 
  1651 * HOL/List: the constructors of type list are now Nil and Cons;
  1652 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1653 course, ML tools referring to List.list.op # etc. have to be adapted;
  1654 
  1655 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1656 disabled by default; run isabelle with option -m HOL to get back to
  1657 the original Gordon/HOL-style output;
  1658 
  1659 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1660 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1661 
  1662 * HOL basic syntax simplified (more orthogonal): all variants of
  1663 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1664 Eps operator is provided as well: "SOME x. P[x]";
  1665 
  1666 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1667 
  1668 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1669 thus available for user theories;
  1670 
  1671 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1672 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1673 time;
  1674 
  1675 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1676 several times and then mp;
  1677 
  1678 
  1679 *** LK ***
  1680 
  1681 * the notation <<...>> is now available as a notation for sequences of
  1682 formulas;
  1683 
  1684 * the simplifier is now installed
  1685 
  1686 * the axiom system has been generalized (thanks to Soren Heilmann)
  1687 
  1688 * the classical reasoner now has a default rule database
  1689 
  1690 
  1691 *** ZF ***
  1692 
  1693 * new primrec section allows primitive recursive functions to be given
  1694 directly (as in HOL) over datatypes and the natural numbers;
  1695 
  1696 * new tactics induct_tac and exhaust_tac for induction (or case
  1697 analysis) over datatypes and the natural numbers;
  1698 
  1699 * the datatype declaration of type T now defines the recursor T_rec;
  1700 
  1701 * simplification automatically does freeness reasoning for datatype
  1702 constructors;
  1703 
  1704 * automatic type-inference, with AddTCs command to insert new
  1705 type-checking rules;
  1706 
  1707 * datatype introduction rules are now added as Safe Introduction rules
  1708 to the claset;
  1709 
  1710 * the syntax "if P then x else y" is now available in addition to
  1711 if(P,x,y);
  1712 
  1713 
  1714 *** Internal programming interfaces ***
  1715 
  1716 * tuned simplifier trace output; new flag debug_simp;
  1717 
  1718 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1719 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1720 
  1721 * AxClass.axclass_tac lost the theory argument;
  1722 
  1723 * tuned current_goals_markers semantics: begin / end goal avoids
  1724 printing empty lines;
  1725 
  1726 * removed prs and prs_fn hook, which was broken because it did not
  1727 include \n in its semantics, forcing writeln to add one
  1728 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1729 string -> unit if you really want to output text without newline;
  1730 
  1731 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1732 plain output, interface builders may have to enable 'isabelle_font'
  1733 mode to get Isabelle font glyphs as before;
  1734 
  1735 * refined token_translation interface; INCOMPATIBILITY: output length
  1736 now of type real instead of int;
  1737 
  1738 * theory loader actions may be traced via new ThyInfo.add_hook
  1739 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1740 your own database of information attached to *whole* theories -- as
  1741 opposed to intra-theory data slots offered via TheoryDataFun;
  1742 
  1743 * proper handling of dangling sort hypotheses (at last!);
  1744 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1745 extra sort hypotheses that can be witnessed from the type signature;
  1746 the force_strip_shyps flag is gone, any remaining shyps are simply
  1747 left in the theorem (with a warning issued by strip_shyps_warning);
  1748 
  1749 
  1750 
  1751 New in Isabelle98-1 (October 1998)
  1752 ----------------------------------
  1753 
  1754 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1755 
  1756 * several changes of automated proof tools;
  1757 
  1758 * HOL: major changes to the inductive and datatype packages, including
  1759 some minor incompatibilities of theory syntax;
  1760 
  1761 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1762 called `inj_on';
  1763 
  1764 * HOL: removed duplicate thms in Arith:
  1765   less_imp_add_less  should be replaced by  trans_less_add1
  1766   le_imp_add_le      should be replaced by  trans_le_add1
  1767 
  1768 * HOL: unary minus is now overloaded (new type constraints may be
  1769 required);
  1770 
  1771 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1772 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1773 now taken as an integer constant.
  1774 
  1775 * Pure: ML function 'theory_of' renamed to 'theory';
  1776 
  1777 
  1778 *** Proof tools ***
  1779 
  1780 * Simplifier:
  1781   1. Asm_full_simp_tac is now more aggressive.
  1782      1. It will sometimes reorient premises if that increases their power to
  1783         simplify.
  1784      2. It does no longer proceed strictly from left to right but may also
  1785         rotate premises to achieve further simplification.
  1786      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1787      old Asm_full_simp_tac in that it does not rotate premises.
  1788   2. The simplifier now knows a little bit about nat-arithmetic.
  1789 
  1790 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1791 allows for selected deletion of wrappers, by introduction of names for
  1792 wrapper functionals.  This implies that addbefore, addSbefore,
  1793 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1794 and that adding two tactics with the same name overwrites the first
  1795 one (emitting a warning).
  1796   type wrapper = (int -> tactic) -> (int -> tactic)
  1797   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1798   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1799   delWrapper, delSWrapper: claset *  string            -> claset
  1800   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1801 
  1802 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1803 semantics; addbefore now affects only the unsafe part of step_tac
  1804 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1805 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1806 by Force_tac;
  1807 
  1808 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1809 compWrapper; added safe wrapper (and access functions for it);
  1810 
  1811 * HOL/split_all_tac is now much faster and fails if there is nothing
  1812 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1813 and the names of the automatically generated variables have changed.
  1814 split_all_tac has moved within claset() from unsafe wrappers to safe
  1815 wrappers, which means that !!-bound variables are split much more
  1816 aggressively, and safe_tac and clarify_tac now split such variables.
  1817 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1818 Note: the same holds for record_split_tac, which does the job of
  1819 split_all_tac for record fields.
  1820 
  1821 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1822 permanently to the default simpset using Addsplits just like
  1823 Addsimps. They can be removed via Delsplits just like
  1824 Delsimps. Lower-case versions are also available.
  1825 
  1826 * HOL/Simplifier: The rule split_if is now part of the default
  1827 simpset. This means that the simplifier will eliminate all occurrences
  1828 of if-then-else in the conclusion of a goal. To prevent this, you can
  1829 either remove split_if completely from the default simpset by
  1830 `Delsplits [split_if]' or remove it in a specific call of the
  1831 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1832 other case splitting rules to/from the default simpset: every datatype
  1833 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1834 t is the name of the datatype).
  1835 
  1836 * Classical reasoner / Simplifier combination: new force_tac (and
  1837 derivatives Force_tac, force) combines rewriting and classical
  1838 reasoning (and whatever other tools) similarly to auto_tac, but is
  1839 aimed to solve the given subgoal completely.
  1840 
  1841 
  1842 *** General ***
  1843 
  1844 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1845 and `goalw': the theory is no longer needed as an explicit argument -
  1846 the current theory context is used; assumptions are no longer returned
  1847 at the ML-level unless one of them starts with ==> or !!; it is
  1848 recommended to convert to these new commands using isatool fixgoal
  1849 (backup your sources first!);
  1850 
  1851 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1852 the current theory context, and 'theory' to lookup stored theories;
  1853 
  1854 * new theory section 'locale' for declaring constants, assumptions and
  1855 definitions that have local scope;
  1856 
  1857 * new theory section 'nonterminals' for purely syntactic types;
  1858 
  1859 * new theory section 'setup' for generic ML setup functions
  1860 (e.g. package initialization);
  1861 
  1862 * the distribution now includes Isabelle icons: see
  1863 lib/logo/isabelle-{small,tiny}.xpm;
  1864 
  1865 * isatool install - install binaries with absolute references to
  1866 ISABELLE_HOME/bin;
  1867 
  1868 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1869 
  1870 * print mode 'emacs' reserved for Isamode;
  1871 
  1872 * support multiple print (ast) translations per constant name;
  1873 
  1874 * theorems involving oracles are now printed with a suffixed [!];
  1875 
  1876 
  1877 *** HOL ***
  1878 
  1879 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1880 
  1881 * HOL/inductive package reorganized and improved: now supports mutual
  1882 definitions such as
  1883 
  1884   inductive EVEN ODD
  1885     intrs
  1886       null "0 : EVEN"
  1887       oddI "n : EVEN ==> Suc n : ODD"
  1888       evenI "n : ODD ==> Suc n : EVEN"
  1889 
  1890 new theorem list "elims" contains an elimination rule for each of the
  1891 recursive sets; inductive definitions now handle disjunctive premises
  1892 correctly (also ZF);
  1893 
  1894 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1895 "mutual_induct" no longer exists - the induction rule is always
  1896 contained in "induct";
  1897 
  1898 
  1899 * HOL/datatype package re-implemented and greatly improved: now
  1900 supports mutually recursive datatypes such as
  1901 
  1902   datatype
  1903     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1904             | SUM ('a aexp) ('a aexp)
  1905             | DIFF ('a aexp) ('a aexp)
  1906             | NUM 'a
  1907   and
  1908     'a bexp = LESS ('a aexp) ('a aexp)
  1909             | AND ('a bexp) ('a bexp)
  1910             | OR ('a bexp) ('a bexp)
  1911 
  1912 as well as indirectly recursive datatypes such as
  1913 
  1914   datatype
  1915     ('a, 'b) term = Var 'a
  1916                   | App 'b ((('a, 'b) term) list)
  1917 
  1918 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  1919 induction on mutually / indirectly recursive datatypes.
  1920 
  1921 Primrec equations are now stored in theory and can be accessed via
  1922 <function_name>.simps.
  1923 
  1924 INCOMPATIBILITIES:
  1925 
  1926   - Theories using datatypes must now have theory Datatype as an
  1927     ancestor.
  1928   - The specific <typename>.induct_tac no longer exists - use the
  1929     generic induct_tac instead.
  1930   - natE has been renamed to nat.exhaust - use exhaust_tac
  1931     instead of res_inst_tac ... natE. Note that the variable
  1932     names in nat.exhaust differ from the names in natE, this
  1933     may cause some "fragile" proofs to fail.
  1934   - The theorems split_<typename>_case and split_<typename>_case_asm
  1935     have been renamed to <typename>.split and <typename>.split_asm.
  1936   - Since default sorts of type variables are now handled correctly,
  1937     some datatype definitions may have to be annotated with explicit
  1938     sort constraints.
  1939   - Primrec definitions no longer require function name and type
  1940     of recursive argument.
  1941 
  1942 Consider using isatool fixdatatype to adapt your theories and proof
  1943 scripts to the new package (backup your sources first!).
  1944 
  1945 
  1946 * HOL/record package: considerably improved implementation; now
  1947 includes concrete syntax for record types, terms, updates; theorems
  1948 for surjective pairing and splitting !!-bound record variables; proof
  1949 support is as follows:
  1950 
  1951   1) standard conversions (selectors or updates applied to record
  1952 constructor terms) are part of the standard simpset;
  1953 
  1954   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  1955 made part of standard simpset and claset via addIffs;
  1956 
  1957   3) a tactic for record field splitting (record_split_tac) is part of
  1958 the standard claset (addSWrapper);
  1959 
  1960 To get a better idea about these rules you may retrieve them via
  1961 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  1962 the name of your record type.
  1963 
  1964 The split tactic 3) conceptually simplifies by the following rule:
  1965 
  1966   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  1967 
  1968 Thus any record variable that is bound by meta-all will automatically
  1969 blow up into some record constructor term, consequently the
  1970 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  1971 solve record problems automatically.
  1972 
  1973 
  1974 * reorganized the main HOL image: HOL/Integ and String loaded by
  1975 default; theory Main includes everything;
  1976 
  1977 * automatic simplification of integer sums and comparisons, using cancellation;
  1978 
  1979 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  1980 
  1981 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  1982 
  1983 * many new identities for unions, intersections, set difference, etc.;
  1984 
  1985 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  1986 called split_if, split_split, split_sum_case and split_nat_case (to go
  1987 with add/delsplits);
  1988 
  1989 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  1990 (?x::unit) = (); this is made part of the default simpset, which COULD
  1991 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  1992 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  1993 unit_abs_eta_conv is added in order to counter the effect of
  1994 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  1995 %u.f();
  1996 
  1997 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  1998 makes more sense);
  1999 
  2000 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2001   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2002   disjointness reasoning but breaking a few old proofs.
  2003 
  2004 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  2005 to 'converse' from 'inverse' (for compatibility with ZF and some
  2006 literature);
  2007 
  2008 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  2009 the well-founded relation;
  2010 
  2011 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  2012     Compl A.  The "Compl" syntax remains available as input syntax for this
  2013     release ONLY.
  2014 
  2015 * HOL/Update: new theory of function updates:
  2016     f(a:=b) == %x. if x=a then b else f x
  2017 may also be iterated as in f(a:=b,c:=d,...);
  2018 
  2019 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  2020 
  2021 * HOL/List:
  2022   - new function list_update written xs[i:=v] that updates the i-th
  2023     list position. May also be iterated as in xs[i:=a,j:=b,...].
  2024   - new function `upt' written [i..j(] which generates the list
  2025     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  2026     bound write [i..j], which is a shorthand for [i..j+1(].
  2027   - new lexicographic orderings and corresponding wellfoundedness theorems.
  2028 
  2029 * HOL/Arith:
  2030   - removed 'pred' (predecessor) function;
  2031   - generalized some theorems about n-1;
  2032   - many new laws about "div" and "mod";
  2033   - new laws about greatest common divisors (see theory ex/Primes);
  2034 
  2035 * HOL/Relation: renamed the relational operator r^-1 "converse"
  2036 instead of "inverse";
  2037 
  2038 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  2039   of the multiset ordering;
  2040 
  2041 * directory HOL/Real: a construction of the reals using Dedekind cuts
  2042   (not included by default);
  2043 
  2044 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  2045 
  2046 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  2047   programs, i.e. different program variables may have different types.
  2048 
  2049 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2050   [previously, this check worked only if the rewrite rule was unconditional]
  2051   Now rew can involve either definitions or equalities (either == or =).
  2052 
  2053 
  2054 *** ZF ***
  2055 
  2056 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  2057   only the theorems proved on ZF.ML;
  2058 
  2059 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2060   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2061   disjointness reasoning but breaking a few old proofs.
  2062 
  2063 * ZF/Update: new theory of function updates
  2064     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  2065   may also be iterated as in f(a:=b,c:=d,...);
  2066 
  2067 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  2068 
  2069 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2070   [previously, this check worked only if the rewrite rule was unconditional]
  2071   Now rew can involve either definitions or equalities (either == or =).
  2072 
  2073 * case_tac provided for compatibility with HOL
  2074     (like the old excluded_middle_tac, but with subgoals swapped)
  2075 
  2076 
  2077 *** Internal programming interfaces ***
  2078 
  2079 * Pure: several new basic modules made available for general use, see
  2080 also src/Pure/README;
  2081 
  2082 * improved the theory data mechanism to support encapsulation (data
  2083 kind name replaced by private Object.kind, acting as authorization
  2084 key); new type-safe user interface via functor TheoryDataFun; generic
  2085 print_data function becomes basically useless;
  2086 
  2087 * removed global_names compatibility flag -- all theory declarations
  2088 are qualified by default;
  2089 
  2090 * module Pure/Syntax now offers quote / antiquote translation
  2091 functions (useful for Hoare logic etc. with implicit dependencies);
  2092 see HOL/ex/Antiquote for an example use;
  2093 
  2094 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2095 cterm -> thm;
  2096 
  2097 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2098 subgoal;
  2099 
  2100 * Display.print_goals function moved to Locale.print_goals;
  2101 
  2102 * standard print function for goals supports current_goals_markers
  2103 variable for marking begin of proof, end of proof, start of goal; the
  2104 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2105 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2106 for example;
  2107 
  2108 
  2109 
  2110 New in Isabelle98 (January 1998)
  2111 --------------------------------
  2112 
  2113 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2114 
  2115 * changed lexical syntax of terms / types: dots made part of long
  2116 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2117 
  2118 * simpset (and claset) reference variable replaced by functions
  2119 simpset / simpset_ref;
  2120 
  2121 * no longer supports theory aliases (via merge) and non-trivial
  2122 implicit merge of thms' signatures;
  2123 
  2124 * most internal names of constants changed due to qualified names;
  2125 
  2126 * changed Pure/Sequence interface (see Pure/seq.ML);
  2127 
  2128 
  2129 *** General Changes ***
  2130 
  2131 * hierachically structured name spaces (for consts, types, axms, thms
  2132 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2133 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2134 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2135 long_names for fully qualified output names; NOTE: ML programs
  2136 (special tactics, packages etc.) referring to internal names may have
  2137 to be adapted to cope with fully qualified names; in case of severe
  2138 backward campatibility problems try setting 'global_names' at compile
  2139 time to have enrything declared within a flat name space; one may also
  2140 fine tune name declarations in theories via the 'global' and 'local'
  2141 section;
  2142 
  2143 * reimplemented the implicit simpset and claset using the new anytype
  2144 data filed in signatures; references simpset:simpset ref etc. are
  2145 replaced by functions simpset:unit->simpset and
  2146 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2147 to patch your ML files accordingly;
  2148 
  2149 * HTML output now includes theory graph data for display with Java
  2150 applet or isatool browser; data generated automatically via isatool
  2151 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2152 
  2153 * defs may now be conditional; improved rewrite_goals_tac to handle
  2154 conditional equations;
  2155 
  2156 * defs now admits additional type arguments, using TYPE('a) syntax;
  2157 
  2158 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2159 creates a new theory node; implicit merge of thms' signatures is
  2160 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2161 transfer:theory->thm->thm in (rare) cases;
  2162 
  2163 * improved handling of draft signatures / theories; draft thms (and
  2164 ctyps, cterms) are automatically promoted to real ones;
  2165 
  2166 * slightly changed interfaces for oracles: admit many per theory, named
  2167 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2168 
  2169 * print_goals: optional output of const types (set show_consts and
  2170 show_types);
  2171 
  2172 * improved output of warnings (###) and errors (***);
  2173 
  2174 * subgoal_tac displays a warning if the new subgoal has type variables;
  2175 
  2176 * removed old README and Makefiles;
  2177 
  2178 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2179 
  2180 * removed obsolete init_pps and init_database;
  2181 
  2182 * deleted the obsolete tactical STATE, which was declared by
  2183     fun STATE tacfun st = tacfun st st;
  2184 
  2185 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2186 (which abbreviates $HOME);
  2187 
  2188 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2189 use isatool fixseq to adapt your ML programs (this works for fully
  2190 qualified references to the Sequence structure only!);
  2191 
  2192 * use_thy no longer requires writable current directory; it always
  2193 reloads .ML *and* .thy file, if either one is out of date;
  2194 
  2195 
  2196 *** Classical Reasoner ***
  2197 
  2198 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2199 tactics that use classical reasoning to simplify a subgoal without
  2200 splitting it into several subgoals;
  2201 
  2202 * Safe_tac: like safe_tac but uses the default claset;
  2203 
  2204 
  2205 *** Simplifier ***
  2206 
  2207 * added simplification meta rules:
  2208     (asm_)(full_)simplify: simpset -> thm -> thm;
  2209 
  2210 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2211 logics (again);
  2212 
  2213 * added prems argument to simplification procedures;
  2214 
  2215 * HOL, FOL, ZF: added infix function `addsplits':
  2216   instead of `<simpset> setloop (split_tac <thms>)'
  2217   you can simply write `<simpset> addsplits <thms>'
  2218 
  2219 
  2220 *** Syntax ***
  2221 
  2222 * TYPE('a) syntax for type reflection terms;
  2223 
  2224 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2225 
  2226 * pretty printer: changed order of mixfix annotation preference (again!);
  2227 
  2228 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2229 
  2230 
  2231 *** HOL ***
  2232 
  2233 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2234   with `addloop' of the simplifier to faciliate case splitting in premises.
  2235 
  2236 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2237 
  2238 * HOL/Auth: new protocol proofs including some for the Internet
  2239   protocol TLS;
  2240 
  2241 * HOL/Map: new theory of `maps' a la VDM;
  2242 
  2243 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2244 cancelling out common nat summands from =, <, <= (in)equalities, or
  2245 differences; simplification procedures nat_cancel_factor for
  2246 cancelling common factor from =, <, <= (in)equalities over natural
  2247 sums; nat_cancel contains both kinds of procedures, it is installed by
  2248 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2249 
  2250 * HOL/simplifier: terms of the form
  2251   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2252   are rewritten to
  2253   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2254   and those of the form
  2255   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2256   are rewritten to
  2257   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2258 
  2259 * HOL/datatype
  2260   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2261 
  2262   P(t_case f1 ... fn x) =
  2263      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2264         ...
  2265        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2266      )
  2267 
  2268   and a theorem `split_t_case_asm' of the form
  2269 
  2270   P(t_case f1 ... fn x) =
  2271     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2272         ...
  2273        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2274      )
  2275   which can be added to a simpset via `addsplits'. The existing theorems
  2276   expand_list_case and expand_option_case have been renamed to
  2277   split_list_case and split_option_case.
  2278 
  2279 * HOL/Arithmetic:
  2280   - `pred n' is automatically converted to `n-1'.
  2281     Users are strongly encouraged not to use `pred' any longer,
  2282     because it will disappear altogether at some point.
  2283   - Users are strongly encouraged to write "0 < n" rather than
  2284     "n ~= 0". Theorems and proof tools have been modified towards this
  2285     `standard'.
  2286 
  2287 * HOL/Lists:
  2288   the function "set_of_list" has been renamed "set" (and its theorems too);
  2289   the function "nth" now takes its arguments in the reverse order and
  2290   has acquired the infix notation "!" as in "xs!n".
  2291 
  2292 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2293 
  2294 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2295   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2296 
  2297 * HOL/record: extensible records with schematic structural subtyping
  2298 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2299 still lacks various theorems and concrete record syntax;
  2300 
  2301 
  2302 *** HOLCF ***
  2303 
  2304 * removed "axioms" and "generated by" sections;
  2305 
  2306 * replaced "ops" section by extended "consts" section, which is capable of
  2307   handling the continuous function space "->" directly;
  2308 
  2309 * domain package:
  2310   . proves theorems immediately and stores them in the theory,
  2311   . creates hierachical name space,
  2312   . now uses normal mixfix annotations (instead of cinfix...),
  2313   . minor changes to some names and values (for consistency),
  2314   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2315   . separator between mutual domain defs: changed "," to "and",
  2316   . improved handling of sort constraints;  now they have to
  2317     appear on the left-hand side of the equations only;
  2318 
  2319 * fixed LAM <x,y,zs>.b syntax;
  2320 
  2321 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2322 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2323 
  2324 
  2325 *** FOL and ZF ***
  2326 
  2327 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2328   with `addloop' of the simplifier to faciliate case splitting in premises.
  2329 
  2330 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2331 in HOL, they strip ALL and --> from proved theorems;
  2332 
  2333 
  2334 
  2335 New in Isabelle94-8 (May 1997)
  2336 ------------------------------
  2337 
  2338 *** General Changes ***
  2339 
  2340 * new utilities to build / run / maintain Isabelle etc. (in parts
  2341 still somewhat experimental); old Makefiles etc. still functional;
  2342 
  2343 * new 'Isabelle System Manual';
  2344 
  2345 * INSTALL text, together with ./configure and ./build scripts;
  2346 
  2347 * reimplemented type inference for greater efficiency, better error
  2348 messages and clean internal interface;
  2349 
  2350 * prlim command for dealing with lots of subgoals (an easier way of
  2351 setting goals_limit);
  2352 
  2353 
  2354 *** Syntax ***
  2355 
  2356 * supports alternative (named) syntax tables (parser and pretty
  2357 printer); internal interface is provided by add_modesyntax(_i);
  2358 
  2359 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2360 be used in conjunction with the Isabelle symbol font; uses the
  2361 "symbols" syntax table;
  2362 
  2363 * added token_translation interface (may translate name tokens in
  2364 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2365 the current print_mode); IMPORTANT: user print translation functions
  2366 are responsible for marking newly introduced bounds
  2367 (Syntax.mark_boundT);
  2368 
  2369 * token translations for modes "xterm" and "xterm_color" that display
  2370 names in bold, underline etc. or colors (which requires a color
  2371 version of xterm);
  2372 
  2373 * infixes may now be declared with names independent of their syntax;
  2374 
  2375 * added typed_print_translation (like print_translation, but may
  2376 access type of constant);
  2377 
  2378 
  2379 *** Classical Reasoner ***
  2380 
  2381 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2382 some limitations.  Blast_tac...
  2383   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2384   + ignores elimination rules that don't have the correct format
  2385         (the conclusion MUST be a formula variable)
  2386   + ignores types, which can make HOL proofs fail
  2387   + rules must not require higher-order unification, e.g. apply_type in ZF
  2388     [message "Function Var's argument not a bound variable" relates to this]
  2389   + its proof strategy is more general but can actually be slower
  2390 
  2391 * substitution with equality assumptions no longer permutes other
  2392 assumptions;
  2393 
  2394 * minor changes in semantics of addafter (now called addaltern); renamed
  2395 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2396 (and access functions for it);
  2397 
  2398 * improved combination of classical reasoner and simplifier:
  2399   + functions for handling clasimpsets
  2400   + improvement of addss: now the simplifier is called _after_ the
  2401     safe steps.
  2402   + safe variant of addss called addSss: uses safe simplifications
  2403     _during_ the safe steps. It is more complete as it allows multiple
  2404     instantiations of unknowns (e.g. with slow_tac).
  2405 
  2406 *** Simplifier ***
  2407 
  2408 * added interface for simplification procedures (functions that
  2409 produce *proven* rewrite rules on the fly, depending on current
  2410 redex);
  2411 
  2412 * ordering on terms as parameter (used for ordered rewriting);
  2413 
  2414 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2415 
  2416 * the solver is now split into a safe and an unsafe part.
  2417 This should be invisible for the normal user, except that the
  2418 functions setsolver and addsolver have been renamed to setSolver and
  2419 addSolver; added safe_asm_full_simp_tac;
  2420 
  2421 
  2422 *** HOL ***
  2423 
  2424 * a generic induction tactic `induct_tac' which works for all datatypes and
  2425 also for type `nat';
  2426 
  2427 * a generic case distinction tactic `exhaust_tac' which works for all
  2428 datatypes and also for type `nat';
  2429 
  2430 * each datatype comes with a function `size';
  2431 
  2432 * patterns in case expressions allow tuple patterns as arguments to
  2433 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2434 
  2435 * primrec now also works with type nat;
  2436 
  2437 * recdef: a new declaration form, allows general recursive functions to be
  2438 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2439 
  2440 * the constant for negation has been renamed from "not" to "Not" to
  2441 harmonize with FOL, ZF, LK, etc.;
  2442 
  2443 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2444 infinite lists;
  2445 
  2446 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2447 
  2448 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2449 problems in commutative rings, using axiomatic type classes for + and *;
  2450 
  2451 * more examples in HOL/MiniML and HOL/Auth;
  2452 
  2453 * more default rewrite rules for quantifiers, union/intersection;
  2454 
  2455 * a new constant `arbitrary == @x.False';
  2456 
  2457 * HOLCF/IOA replaces old HOL/IOA;
  2458 
  2459 * HOLCF changes: derived all rules and arities
  2460   + axiomatic type classes instead of classes
  2461   + typedef instead of faking type definitions
  2462   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2463   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2464   + eliminated the types void, one, tr
  2465   + use unit lift and bool lift (with translations) instead of one and tr
  2466   + eliminated blift from Lift3.thy (use Def instead of blift)
  2467   all eliminated rules are derived as theorems --> no visible changes ;
  2468 
  2469 
  2470 *** ZF ***
  2471 
  2472 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2473 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2474 as ZF_cs addSIs [equalityI];
  2475 
  2476 
  2477 
  2478 New in Isabelle94-7 (November 96)
  2479 ---------------------------------
  2480 
  2481 * allowing negative levels (as offsets) in prlev and choplev;
  2482 
  2483 * super-linear speedup for large simplifications;
  2484 
  2485 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2486 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2487 FAIL); can suppress it using the command Delsimps (ex_simps @
  2488 all_simps); De Morgan laws are also now included, by default;
  2489 
  2490 * improved printing of ==>  :  ~:
  2491 
  2492 * new object-logic "Sequents" adds linear logic, while replacing LK
  2493 and Modal (thanks to Sara Kalvala);
  2494 
  2495 * HOL/Auth: correctness proofs for authentication protocols;
  2496 
  2497 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2498 examples on HOL/Auth);
  2499 
  2500 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2501 the rewriter and classical reasoner simultaneously;
  2502 
  2503 * function uresult no longer returns theorems in "standard" format;
  2504 regain previous version by: val uresult = standard o uresult;
  2505 
  2506 
  2507 
  2508 New in Isabelle94-6
  2509 -------------------
  2510 
  2511 * oracles -- these establish an interface between Isabelle and trusted
  2512 external reasoners, which may deliver results as theorems;
  2513 
  2514 * proof objects (in particular record all uses of oracles);
  2515 
  2516 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2517 
  2518 * "constdefs" section in theory files;
  2519 
  2520 * "primrec" section (HOL) no longer requires names;
  2521 
  2522 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2523 
  2524 
  2525 
  2526 New in Isabelle94-5
  2527 -------------------
  2528 
  2529 * reduced space requirements;
  2530 
  2531 * automatic HTML generation from theories;
  2532 
  2533 * theory files no longer require "..." (quotes) around most types;
  2534 
  2535 * new examples, including two proofs of the Church-Rosser theorem;
  2536 
  2537 * non-curried (1994) version of HOL is no longer distributed;
  2538 
  2539 
  2540 
  2541 New in Isabelle94-4
  2542 -------------------
  2543 
  2544 * greatly reduced space requirements;
  2545 
  2546 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2547 
  2548 * searchable theorem database (see the section "Retrieving theorems" on
  2549 page 8 of the Reference Manual);
  2550 
  2551 * new examples, including Grabczewski's monumental case study of the
  2552 Axiom of Choice;
  2553 
  2554 * The previous version of HOL renamed to Old_HOL;
  2555 
  2556 * The new version of HOL (previously called CHOL) uses a curried syntax
  2557 for functions.  Application looks like f a b instead of f(a,b);
  2558 
  2559 * Mutually recursive inductive definitions finally work in HOL;
  2560 
  2561 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2562 translates to the operator "split";
  2563 
  2564 
  2565 
  2566 New in Isabelle94-3
  2567 -------------------
  2568 
  2569 * new infix operator, addss, allowing the classical reasoner to
  2570 perform simplification at each step of its search.  Example:
  2571         fast_tac (cs addss ss)
  2572 
  2573 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2574 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2575 look like (a,b) instead of <a,b>;
  2576 
  2577 * PLEASE NOTE: CHOL will eventually replace HOL!
  2578 
  2579 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2580 It translates to the operator "split".  A new theory of integers is available;
  2581 
  2582 * In ZF, integer numerals now denote two's-complement binary integers.
  2583 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2584 
  2585 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2586 of the Axiom of Choice;
  2587 
  2588 
  2589 
  2590 New in Isabelle94-2
  2591 -------------------
  2592 
  2593 * Significantly faster resolution;
  2594 
  2595 * the different sections in a .thy file can now be mixed and repeated
  2596 freely;
  2597 
  2598 * Database of theorems for FOL, HOL and ZF.  New
  2599 commands including qed, qed_goal and bind_thm store theorems in the database.
  2600 
  2601 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2602 a given theory (thms_of), or find out what theory a theorem was proved in
  2603 (theory_of_thm);
  2604 
  2605 * Bugs fixed in the inductive definition and datatype packages;
  2606 
  2607 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2608 and HOL_dup_cs obsolete;
  2609 
  2610 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2611 have been removed;
  2612 
  2613 * Simpler definition of function space in ZF;
  2614 
  2615 * new results about cardinal and ordinal arithmetic in ZF;
  2616 
  2617 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2618 types;
  2619 
  2620 
  2621 $Id$