NEWS
author wenzelm
Sun Jun 06 14:20:03 2004 +0200 (2004-06-06)
changeset 14878 b884a7ba7238
parent 14854 61bdf2ae4dc5
child 14885 0a840138dcd7
permissions -rw-r--r--
HOL: symbolic syntax of Eps;
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** General ***
     8 
     9 * Pure: considerably improved version of 'constdefs' command.  Now
    10   performs automatic type-inference of declared constants; additional
    11   support for local structure declarations (cf. locales and HOL
    12   records), see also isar-ref manual.  Potential INCOMPATIBILITY: need
    13   to observe strictly sequential dependencies of definitions within a
    14   single 'constdefs' section; moreover, the declared name needs to be
    15   an identifier.  If all fails, consider to fall back on 'consts' and
    16   'defs' separately.
    17 
    18 * Pure: improved indexed syntax and implicit structures.  First of
    19   all, indexed syntax provides a notational device for subscripted
    20   application, using the new syntax \<^bsub>term\<^esub> for arbitrary
    21   expressions.  Secondly, in a local context with structure
    22   declarations, number indexes \<^sub>n or the empty index (default
    23   number 1) refer to a certain fixed variable implicitly; option
    24   show_structs controls printing of implicit structures.  Typical
    25   applications of these concepts involve record types and locales.
    26 
    27 * Pure: clear separation of logical types and nonterminals, where the
    28   latter may only occur in 'syntax' specifications or type
    29   abbreviations.  Before that distinction was only partially
    30   implemented via type class "logic" vs. "{}".  Potential
    31   INCOMPATIBILITY in rare cases of improper use of 'types'/'consts'
    32   instead of 'nonterminals'/'syntax'.  Some very exotic syntax
    33   specifications may require further adaption (e.g. Cube/Base.thy).
    34 
    35 * Pure: removed obsolete type class "logic", use the top sort {}
    36   instead.  Note that non-logical types should be declared as
    37   'nonterminals' rather than 'types'.  INCOMPATIBILITY for new
    38   object-logic specifications.
    39 
    40 * Pure/Syntax: inner syntax includes (*(*nested*) comments*).
    41 
    42 * Pure/Syntax: pretty pinter now supports unbreakable blocks,
    43   specified in mixfix annotations as "(00...)".
    44 
    45 * Pure/Syntax: 'advanced' translation functions (parse_translation
    46   etc.) may depend on the signature of the theory context being
    47   presently used for parsing/printing, see also isar-ref manual.
    48 
    49 * Pure: tuned internal renaming of symbolic identifiers -- attach
    50   primes instead of base 26 numbers.
    51 
    52 * ML: all output via channels of writeln/warning/error etc. is now
    53   passed through Output.output.  This gives interface builders a
    54   chance to adapt text encodings in arbitrary manners (say as XML
    55   entities); see the hook provided by Output.add_mode.  On the other
    56   hand, results of Pretty.string_of/str_of (including string_of_term,
    57   string_of_thm etc.) are still 'raw' (containing funny \<^raw...>
    58   symbols), which requires separate application of Output.output
    59   whenever strings are *not* passed on to writeln/warning/error etc.
    60 
    61 
    62 *** HOL ***
    63 
    64 * HOL/record: reimplementation of records. Improved scalability for
    65   records with many fields, avoiding performance problems for type
    66   inference. Records are no longer composed of nested field types, but
    67   of nested extension types. Therefore the record type only grows
    68   linear in the number of extensions and not in the number of fields.
    69   The top-level (users) view on records is preserved.  Potential
    70   INCOMPATIBILITY only in strange cases, where the theory depends on
    71   the old record representation. The type generated for a record is
    72   called <record_name>_ext_type.
    73 
    74 * HOL: symbolic syntax of Hilbert Choice Operator is now as follows:
    75 
    76   syntax (epsilon)
    77     "_Eps" :: "[pttrn, bool] => 'a"    ("(3\<some>_./ _)" [0, 10] 10)
    78 
    79   The symbol \<some> is displayed as the alternative epsilon of LaTeX
    80   and x-symbol; use option '-m epsilon' to get it actually printed.
    81   Moreover, the mathematically important symbolic identifier
    82   \<epsilon> becomes available as variable, constant etc.
    83 
    84 * Simplifier: "record_upd_simproc" for simplification of multiple
    85   record updates enabled by default.  INCOMPATIBILITY: old proofs
    86   break occasionally, since simplification is more powerful by
    87   default.
    88 
    89 
    90 *** HOLCF ***
    91 
    92 * HOLCF: discontinued special version of 'constdefs' (which used to
    93   support continuous functions) in favor of the general Pure one with
    94   full type-inference.
    95 
    96 
    97 
    98 New in Isabelle2004 (April 2004)
    99 --------------------------------
   100 
   101 *** General ***
   102 
   103 * Provers/order.ML:  new efficient reasoner for partial and linear orders.
   104   Replaces linorder.ML.
   105 
   106 * Pure: Greek letters (except small lambda, \<lambda>), as well as Gothic
   107   (\<aa>...\<zz>\<AA>...\<ZZ>), calligraphic (\<A>...\<Z>), and Euler
   108   (\<a>...\<z>), are now considered normal letters, and can therefore
   109   be used anywhere where an ASCII letter (a...zA...Z) has until
   110   now. COMPATIBILITY: This obviously changes the parsing of some
   111   terms, especially where a symbol has been used as a binder, say
   112   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed
   113   as an identifier.  Fix it by inserting a space around former
   114   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in
   115   existing theory and ML files.
   116 
   117 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.
   118 
   119 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now
   120   allowed in identifiers. Similar to Greek letters \<^isub> is now considered
   121   a normal (but invisible) letter. For multiple letter subscripts repeat
   122   \<^isub> like this: x\<^isub>1\<^isub>2.
   123 
   124 * Pure: There are now sub-/superscripts that can span more than one
   125   character. Text between \<^bsub> and \<^esub> is set in subscript in
   126   ProofGeneral and LaTeX, text between \<^bsup> and \<^esup> in
   127   superscript. The new control characters are not identifier parts.
   128 
   129 * Pure: Control-symbols of the form \<^raw:...> will literally print the
   130   content of "..." to the latex file instead of \isacntrl... . The "..."
   131   may consist of any printable characters excluding the end bracket >.
   132 
   133 * Pure: Using new Isar command "finalconsts" (or the ML functions
   134   Theory.add_finals or Theory.add_finals_i) it is now possible to
   135   declare constants "final", which prevents their being given a definition
   136   later.  It is useful for constants whose behaviour is fixed axiomatically
   137   rather than definitionally, such as the meta-logic connectives.
   138 
   139 * Pure: 'instance' now handles general arities with general sorts
   140   (i.e. intersections of classes),
   141 
   142 * Presentation: generated HTML now uses a CSS style sheet to make layout
   143   (somewhat) independent of content. It is copied from lib/html/isabelle.css.
   144   It can be changed to alter the colors/layout of generated pages.
   145 
   146 
   147 *** Isar ***
   148 
   149 * Tactic emulation methods rule_tac, erule_tac, drule_tac, frule_tac,
   150   cut_tac, subgoal_tac and thin_tac:
   151   - Now understand static (Isar) contexts.  As a consequence, users of Isar
   152     locales are no longer forced to write Isar proof scripts.
   153     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
   154     emulations.
   155   - INCOMPATIBILITY: names of variables to be instantiated may no
   156     longer be enclosed in quotes.  Instead, precede variable name with `?'.
   157     This is consistent with the instantiation attribute "where".
   158 
   159 * Attributes "where" and "of":
   160   - Now take type variables of instantiated theorem into account when reading
   161     the instantiation string.  This fixes a bug that caused instantiated
   162     theorems to have too special types in some circumstances.
   163   - "where" permits explicit instantiations of type variables.
   164 
   165 * Calculation commands "moreover" and "also" no longer interfere with
   166   current facts ("this"), admitting arbitrary combinations with "then"
   167   and derived forms.
   168 
   169 * Locales:
   170   - Goal statements involving the context element "includes" no longer
   171     generate theorems with internal delta predicates (those ending on
   172     "_axioms") in the premise.
   173     Resolve particular premise with <locale>.intro to obtain old form.
   174   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
   175     specification and "includes" elements in goal statement.
   176   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
   177     [intro?] and [elim?] (respectively) by default.
   178   - Experimental command for instantiation of locales in proof contexts:
   179         instantiate <label>[<attrs>]: <loc>
   180     Instantiates locale <loc> and adds all its theorems to the current context
   181     taking into account their attributes.  Label and attrs are optional
   182     modifiers, like in theorem declarations.  If present, names of
   183     instantiated theorems are qualified with <label>, and the attributes
   184     <attrs> are applied after any attributes these theorems might have already.
   185       If the locale has assumptions, a chained fact of the form
   186     "<loc> t1 ... tn" is expected from which instantiations of the parameters
   187     are derived.  The command does not support old-style locales declared
   188     with "locale (open)".
   189       A few (very simple) examples can be found in FOL/ex/LocaleInst.thy.
   190 
   191 * HOL: Tactic emulation methods induct_tac and case_tac understand static
   192   (Isar) contexts.
   193 
   194 
   195 *** HOL ***
   196 
   197 * Proof import: new image HOL4 contains the imported library from
   198   the HOL4 system with about 2500 theorems. It is imported by
   199   replaying proof terms produced by HOL4 in Isabelle. The HOL4 image
   200   can be used like any other Isabelle image.  See
   201   HOL/Import/HOL/README for more information.
   202 
   203 * Simplifier:
   204   - Much improved handling of linear and partial orders.
   205     Reasoners for linear and partial orders are set up for type classes
   206     "linorder" and "order" respectively, and are added to the default simpset
   207     as solvers.  This means that the simplifier can build transitivity chains
   208     to solve goals from the assumptions.
   209   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications
   210     of blast or auto after simplification become unnecessary because the goal
   211     is solved by simplification already.
   212 
   213 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws,
   214     all proved in axiomatic type classes for semirings, rings and fields.
   215 
   216 * Numerics:
   217   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are
   218     now formalized using the Ring_and_Field theory mentioned above.
   219   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently
   220     than before, because now they are set up once in a generic manner.
   221   - INCOMPATIBILITY: many type-specific arithmetic laws have gone.
   222     Look for the general versions in Ring_and_Field (and Power if they concern
   223     exponentiation).
   224 
   225 * Type "rat" of the rational numbers is now available in HOL-Complex.
   226 
   227 * Records:
   228   - Record types are now by default printed with their type abbreviation
   229     instead of the list of all field types. This can be configured via
   230     the reference "print_record_type_abbr".
   231   - Simproc "record_upd_simproc" for simplification of multiple updates added
   232     (not enabled by default).
   233   - Simproc "record_ex_sel_eq_simproc" to simplify EX x. sel r = x resp.
   234     EX x. x = sel r to True (not enabled by default).
   235   - Tactic "record_split_simp_tac" to split and simplify records added.
   236 
   237 * 'specification' command added, allowing for definition by
   238   specification.  There is also an 'ax_specification' command that
   239   introduces the new constants axiomatically.
   240 
   241 * arith(_tac) is now able to generate counterexamples for reals as well.
   242 
   243 * HOL-Algebra: new locale "ring" for non-commutative rings.
   244 
   245 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
   246   definitions, thanks to Sava Krsti\'{c} and John Matthews.
   247 
   248 * HOL-Matrix: a first theory for matrices in HOL with an application of
   249   matrix theory to linear programming.
   250 
   251 * Unions and Intersections:
   252   The x-symbol output syntax of UN and INT has been changed
   253   from "\<Union>x \<in> A. B" to "\<Union\<^bsub>x \<in> A\<^esub> B"
   254   i.e. the index formulae has become a subscript, like in normal math.
   255   Similarly for "\<Union>x. B", and for \<Inter> instead of \<Union>.
   256   The subscript version is also accepted as input syntax.
   257 
   258 * Unions and Intersections over Intervals:
   259   There is new short syntax "UN i<=n. A" for "UN i:{0..n}. A". There is
   260   also an x-symbol version with subscripts "\<Union>\<^bsub>i <= n\<^esub>. A"
   261   like in normal math, and corresponding versions for < and for intersection.
   262 
   263 * ML: the legacy theory structures Int and List have been removed. They had
   264   conflicted with ML Basis Library structures having the same names.
   265 
   266 * 'refute' command added to search for (finite) countermodels.  Only works
   267   for a fragment of HOL.  The installation of an external SAT solver is
   268   highly recommended.  See "HOL/Refute.thy" for details.
   269 
   270 * 'quickcheck' command: Allows to find counterexamples by evaluating
   271   formulae under an assignment of free variables to random values.
   272   In contrast to 'refute', it can deal with inductive datatypes,
   273   but cannot handle quantifiers. See "HOL/ex/Quickcheck_Examples.thy"
   274   for examples.
   275 
   276 
   277 *** HOLCF ***
   278 
   279 * Streams now come with concatenation and are part of the HOLCF image
   280 
   281 
   282 
   283 New in Isabelle2003 (May 2003)
   284 ------------------------------
   285 
   286 *** General ***
   287 
   288 * Provers/simplifier:
   289 
   290   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   291     Assumptions are now subject to complete mutual simplification,
   292     not just from left to right. The simplifier now preserves
   293     the order of assumptions.
   294 
   295     Potential INCOMPATIBILITY:
   296 
   297     -- simp sometimes diverges where the old version did
   298        not, e.g. invoking simp on the goal
   299 
   300         [| P (f x); y = x; f x = f y |] ==> Q
   301 
   302        now gives rise to the infinite reduction sequence
   303 
   304         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   305 
   306        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   307        kind of problem.
   308 
   309     -- Tactics combining classical reasoner and simplification (such as auto)
   310        are also affected by this change, because many of them rely on
   311        simp. They may sometimes diverge as well or yield a different numbers
   312        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   313        in case of problems. Sometimes subsequent calls to the classical
   314        reasoner will fail because a preceeding call to the simplifier too
   315        eagerly simplified the goal, e.g. deleted redundant premises.
   316 
   317   - The simplifier trace now shows the names of the applied rewrite rules
   318 
   319   - You can limit the number of recursive invocations of the simplifier
   320     during conditional rewriting (where the simplifie tries to solve the
   321     conditions before applying the rewrite rule):
   322     ML "simp_depth_limit := n"
   323     where n is an integer. Thus you can force termination where previously
   324     the simplifier would diverge.
   325 
   326   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   327 
   328   - No longer aborts on failed congruence proof.  Instead, the
   329     congruence is ignored.
   330 
   331 * Pure: New generic framework for extracting programs from constructive
   332   proofs. See HOL/Extraction.thy for an example instantiation, as well
   333   as HOL/Extraction for some case studies.
   334 
   335 * Pure: The main goal of the proof state is no longer shown by default, only
   336 the subgoals. This behaviour is controlled by a new flag.
   337    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   338 (ML: Proof.show_main_goal).
   339 
   340 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   341 rules whose conclusion matches subgoal 1:
   342       PG menu: Isabelle/Isar -> Show me -> matching rules
   343 The rules are ordered by how closely they match the subgoal.
   344 In particular, rules that solve a subgoal outright are displayed first
   345 (or rather last, the way they are printed).
   346 (ML: ProofGeneral.print_intros())
   347 
   348 * Pure: New flag trace_unify_fail causes unification to print
   349 diagnostic information (PG: in trace buffer) when it fails. This is
   350 useful for figuring out why single step proofs like rule, erule or
   351 assumption failed.
   352 
   353 * Pure: Locale specifications now produce predicate definitions
   354 according to the body of text (covering assumptions modulo local
   355 definitions); predicate "loc_axioms" covers newly introduced text,
   356 while "loc" is cumulative wrt. all included locale expressions; the
   357 latter view is presented only on export into the global theory
   358 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   359 on the old view without predicates;
   360 
   361 * Pure: predefined locales "var" and "struct" are useful for sharing
   362 parameters (as in CASL, for example); just specify something like
   363 ``var x + var y + struct M'' as import;
   364 
   365 * Pure: improved thms_containing: proper indexing of facts instead of
   366 raw theorems; check validity of results wrt. current name space;
   367 include local facts of proof configuration (also covers active
   368 locales), cover fixed variables in index; may use "_" in term
   369 specification; an optional limit for the number of printed facts may
   370 be given (the default is 40);
   371 
   372 * Pure: disallow duplicate fact bindings within new-style theory files
   373 (batch-mode only);
   374 
   375 * Provers: improved induct method: assumptions introduced by case
   376 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   377 the goal statement); "foo" still refers to all facts collectively;
   378 
   379 * Provers: the function blast.overloaded has been removed: all constants
   380 are regarded as potentially overloaded, which improves robustness in exchange
   381 for slight decrease in efficiency;
   382 
   383 * Provers/linorder: New generic prover for transitivity reasoning over
   384 linear orders.  Note: this prover is not efficient!
   385 
   386 * Isar: preview of problems to finish 'show' now produce an error
   387 rather than just a warning (in interactive mode);
   388 
   389 
   390 *** HOL ***
   391 
   392 * arith(_tac)
   393 
   394  - Produces a counter example if it cannot prove a goal.
   395    Note that the counter example may be spurious if the goal is not a formula
   396    of quantifier-free linear arithmetic.
   397    In ProofGeneral the counter example appears in the trace buffer.
   398 
   399  - Knows about div k and mod k where k is a numeral of type nat or int.
   400 
   401  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   402    linear arithmetic fails. This takes account of quantifiers and divisibility.
   403    Presburger arithmetic can also be called explicitly via presburger(_tac).
   404 
   405 * simp's arithmetic capabilities have been enhanced a bit: it now
   406 takes ~= in premises into account (by performing a case split);
   407 
   408 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   409 are distributed over a sum of terms;
   410 
   411 * New tactic "trans_tac" and method "trans" instantiate
   412 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   413 "<=", "<" and "=").
   414 
   415 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main
   416 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   417 
   418 * 'typedef' command has new option "open" to suppress the set
   419 definition;
   420 
   421 * functions Min and Max on finite sets have been introduced (theory
   422 Finite_Set);
   423 
   424 * attribute [symmetric] now works for relations as well; it turns
   425 (x,y) : R^-1 into (y,x) : R, and vice versa;
   426 
   427 * induct over a !!-quantified statement (say !!x1..xn):
   428   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   429 
   430 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   431 %x. None. Warning: empty_def now refers to the previously hidden definition
   432 of the empty set.
   433 
   434 * Algebra: formalization of classical algebra.  Intended as base for
   435 any algebraic development in Isabelle.  Currently covers group theory
   436 (up to Sylow's theorem) and ring theory (Universal Property of
   437 Univariate Polynomials).  Contributions welcome;
   438 
   439 * GroupTheory: deleted, since its material has been moved to Algebra;
   440 
   441 * Complex: new directory of the complex numbers with numeric constants,
   442 nonstandard complex numbers, and some complex analysis, standard and
   443 nonstandard (Jacques Fleuriot);
   444 
   445 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   446 
   447 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques
   448 Fleuriot);
   449 
   450 * Real/HahnBanach: updated and adapted to locales;
   451 
   452 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   453 Gray and Kramer);
   454 
   455 * UNITY: added the Meier-Sanders theory of progress sets;
   456 
   457 * MicroJava: bytecode verifier and lightweight bytecode verifier
   458 as abstract algorithms, instantiated to the JVM;
   459 
   460 * Bali: Java source language formalization. Type system, operational
   461 semantics, axiomatic semantics. Supported language features:
   462 classes, interfaces, objects,virtual methods, static methods,
   463 static/instance fields, arrays, access modifiers, definite
   464 assignment, exceptions.
   465 
   466 
   467 *** ZF ***
   468 
   469 * ZF/Constructible: consistency proof for AC (Gödel's constructible
   470 universe, etc.);
   471 
   472 * Main ZF: virtually all theories converted to new-style format;
   473 
   474 
   475 *** ML ***
   476 
   477 * Pure: Tactic.prove provides sane interface for internal proofs;
   478 omits the infamous "standard" operation, so this is more appropriate
   479 than prove_goalw_cterm in many situations (e.g. in simprocs);
   480 
   481 * Pure: improved error reporting of simprocs;
   482 
   483 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   484 up simprocs;
   485 
   486 
   487 *** Document preparation ***
   488 
   489 * uses \par instead of \\ for line breaks in theory text. This may
   490 shift some page breaks in large documents. To get the old behaviour
   491 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   492 
   493 * minimized dependencies of isabelle.sty and isabellesym.sty on
   494 other packages
   495 
   496 * \<euro> now needs package babel/greek instead of marvosym (which
   497 broke \Rightarrow)
   498 
   499 * normal size for \<zero>...\<nine> (uses \mathbf instead of
   500 textcomp package)
   501 
   502 
   503 
   504 New in Isabelle2002 (March 2002)
   505 --------------------------------
   506 
   507 *** Document preparation ***
   508 
   509 * greatly simplified document preparation setup, including more
   510 graceful interpretation of isatool usedir -i/-d/-D options, and more
   511 instructive isatool mkdir; users should basically be able to get
   512 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   513 users may run a separate document processing stage manually like this:
   514 "isatool usedir -D output HOL Test && isatool document Test/output";
   515 
   516 * theory dependency graph may now be incorporated into documents;
   517 isatool usedir -g true will produce session_graph.eps/.pdf for use
   518 with \includegraphics of LaTeX;
   519 
   520 * proper spacing of consecutive markup elements, especially text
   521 blocks after section headings;
   522 
   523 * support bold style (for single symbols only), input syntax is like
   524 this: "\<^bold>\<alpha>" or "\<^bold>A";
   525 
   526 * \<bullet> is now output as bold \cdot by default, which looks much
   527 better in printed text;
   528 
   529 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   530 note that these symbols are currently unavailable in Proof General /
   531 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   532 
   533 * isatool latex no longer depends on changed TEXINPUTS, instead
   534 isatool document copies the Isabelle style files to the target
   535 location;
   536 
   537 
   538 *** Isar ***
   539 
   540 * Pure/Provers: improved proof by cases and induction;
   541   - 'case' command admits impromptu naming of parameters (such as
   542     "case (Suc n)");
   543   - 'induct' method divinates rule instantiation from the inductive
   544     claim; no longer requires excessive ?P bindings for proper
   545     instantiation of cases;
   546   - 'induct' method properly enumerates all possibilities of set/type
   547     rules; as a consequence facts may be also passed through *type*
   548     rules without further ado;
   549   - 'induct' method now derives symbolic cases from the *rulified*
   550     rule (before it used to rulify cases stemming from the internal
   551     atomized version); this means that the context of a non-atomic
   552     statement becomes is included in the hypothesis, avoiding the
   553     slightly cumbersome show "PROP ?case" form;
   554   - 'induct' may now use elim-style induction rules without chaining
   555     facts, using ``missing'' premises from the goal state; this allows
   556     rules stemming from inductive sets to be applied in unstructured
   557     scripts, while still benefitting from proper handling of non-atomic
   558     statements; NB: major inductive premises need to be put first, all
   559     the rest of the goal is passed through the induction;
   560   - 'induct' proper support for mutual induction involving non-atomic
   561     rule statements (uses the new concept of simultaneous goals, see
   562     below);
   563   - append all possible rule selections, but only use the first
   564     success (no backtracking);
   565   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   566   - undeclared rule case names default to numbers 1, 2, 3, ...;
   567   - added 'print_induct_rules' (covered by help item in recent Proof
   568     General versions);
   569   - moved induct/cases attributes to Pure, methods to Provers;
   570   - generic method setup instantiated for FOL and HOL;
   571 
   572 * Pure: support multiple simultaneous goal statements, for example
   573 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   574 meta-level mechanism, this acts as if several individual goals had
   575 been stated separately; in particular common proof methods need to be
   576 repeated in order to cover all claims; note that a single elimination
   577 step is *not* sufficient to establish the two conjunctions, so this
   578 fails:
   579 
   580   assume "A & B" then have A and B ..   (*".." fails*)
   581 
   582 better use "obtain" in situations as above; alternative refer to
   583 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   584 
   585 * Pure: proper integration with ``locales''; unlike the original
   586 version by Florian Kammüller, Isar locales package high-level proof
   587 contexts rather than raw logical ones (e.g. we admit to include
   588 attributes everywhere); operations on locales include merge and
   589 rename; support for implicit arguments (``structures''); simultaneous
   590 type-inference over imports and text; see also HOL/ex/Locales.thy for
   591 some examples;
   592 
   593 * Pure: the following commands have been ``localized'', supporting a
   594 target locale specification "(in name)": 'lemma', 'theorem',
   595 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   596 stored both within the locale and at the theory level (exported and
   597 qualified by the locale name);
   598 
   599 * Pure: theory goals may now be specified in ``long'' form, with
   600 ad-hoc contexts consisting of arbitrary locale elements. for example
   601 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   602 definitions may be given, too); the result is a meta-level rule with
   603 the context elements being discharged in the obvious way;
   604 
   605 * Pure: new proof command 'using' allows to augment currently used
   606 facts after a goal statement ('using' is syntactically analogous to
   607 'apply', but acts on the goal's facts only); this allows chained facts
   608 to be separated into parts given before and after a claim, as in
   609 ``from a and b have C using d and e <proof>'';
   610 
   611 * Pure: renamed "antecedent" case to "rule_context";
   612 
   613 * Pure: new 'judgment' command records explicit information about the
   614 object-logic embedding (used by several tools internally); no longer
   615 use hard-wired "Trueprop";
   616 
   617 * Pure: added 'corollary' command;
   618 
   619 * Pure: fixed 'token_translation' command;
   620 
   621 * Pure: removed obsolete 'exported' attribute;
   622 
   623 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   624 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   625 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   626 
   627 * Pure: method 'atomize' presents local goal premises as object-level
   628 statements (atomic meta-level propositions); setup controlled via
   629 rewrite rules declarations of 'atomize' attribute; example
   630 application: 'induct' method with proper rule statements in improper
   631 proof *scripts*;
   632 
   633 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   634 now consider the syntactic context of assumptions, giving a better
   635 chance to get type-inference of the arguments right (this is
   636 especially important for locales);
   637 
   638 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   639 mode;
   640 
   641 * Pure/obtain: the formal conclusion "thesis", being marked as
   642 ``internal'', may no longer be reference directly in the text;
   643 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   644 situations;
   645 
   646 * Pure: generic 'sym' attribute which declares a rule both as pure
   647 'elim?' and for the 'symmetric' operation;
   648 
   649 * Pure: marginal comments ``--'' may now occur just anywhere in the
   650 text; the fixed correlation with particular command syntax has been
   651 discontinued;
   652 
   653 * Pure: new method 'rules' is particularly well-suited for proof
   654 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   655 but often produces more compact proof terms with less detours;
   656 
   657 * Pure/Provers/classical: simplified integration with pure rule
   658 attributes and methods; the classical "intro?/elim?/dest?"
   659 declarations coincide with the pure ones; the "rule" method no longer
   660 includes classically swapped intros; "intro" and "elim" methods no
   661 longer pick rules from the context; also got rid of ML declarations
   662 AddXIs/AddXEs/AddXDs; all of this has some potential for
   663 INCOMPATIBILITY;
   664 
   665 * Provers/classical: attribute 'swapped' produces classical inversions
   666 of introduction rules;
   667 
   668 * Provers/simplifier: 'simplified' attribute may refer to explicit
   669 rules instead of full simplifier context; 'iff' attribute handles
   670 conditional rules;
   671 
   672 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   673 
   674 * HOL: 'recdef' now fails on unfinished automated proofs, use
   675 "(permissive)" option to recover old behavior;
   676 
   677 * HOL: 'inductive' no longer features separate (collective) attributes
   678 for 'intros' (was found too confusing);
   679 
   680 * HOL: properly declared induction rules less_induct and
   681 wf_induct_rule;
   682 
   683 
   684 *** HOL ***
   685 
   686 * HOL: moved over to sane numeral syntax; the new policy is as
   687 follows:
   688 
   689   - 0 and 1 are polymorphic constants, which are defined on any
   690   numeric type (nat, int, real etc.);
   691 
   692   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   693   binary representation internally;
   694 
   695   - type nat has special constructor Suc, and generally prefers Suc 0
   696   over 1::nat and Suc (Suc 0) over 2::nat;
   697 
   698 This change may cause significant problems of INCOMPATIBILITY; here
   699 are some hints on converting existing sources:
   700 
   701   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   702   entities, so expressions involving "-" (unary or binary minus) need
   703   to be spaced properly;
   704 
   705   - existing occurrences of "1" may need to be constraint "1::nat" or
   706   even replaced by Suc 0; similar for old "2";
   707 
   708   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   709 
   710   - remove all special provisions on numerals in proofs;
   711 
   712 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   713 representation (depends on bin_arith_simps in the default context);
   714 
   715 * HOL: symbolic syntax for x^2 (numeral 2);
   716 
   717 * HOL: the class of all HOL types is now called "type" rather than
   718 "term"; INCOMPATIBILITY, need to adapt references to this type class
   719 in axclass/classes, instance/arities, and (usually rare) occurrences
   720 in typings (of consts etc.); internally the class is called
   721 "HOL.type", ML programs should refer to HOLogic.typeS;
   722 
   723 * HOL/record package improvements:
   724   - new derived operations "fields" to build a partial record section,
   725     "extend" to promote a fixed record to a record scheme, and
   726     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   727     declared as simp by default;
   728   - shared operations ("more", "fields", etc.) now need to be always
   729     qualified) --- potential INCOMPATIBILITY;
   730   - removed "make_scheme" operations (use "make" with "extend") --
   731     INCOMPATIBILITY;
   732   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   733   - provides cases/induct rules for use with corresponding Isar
   734     methods (for concrete records, record schemes, concrete more
   735     parts, and schematic more parts -- in that order);
   736   - internal definitions directly based on a light-weight abstract
   737     theory of product types over typedef rather than datatype;
   738 
   739 * HOL: generic code generator for generating executable ML code from
   740 specifications; specific support for HOL constructs such as inductive
   741 datatypes and sets, as well as recursive functions; can be invoked
   742 via 'generate_code' theory section;
   743 
   744 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   745 
   746 * HOL: consolidated and renamed several theories.  In particular:
   747         Ord.thy has been absorbed into HOL.thy
   748         String.thy has been absorbed into List.thy
   749 
   750 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   751 (beware of argument permutation!);
   752 
   753 * HOL: linorder_less_split superseded by linorder_cases;
   754 
   755 * HOL/List: "nodups" renamed to "distinct";
   756 
   757 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   758 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   759   - Ex_def has changed, now need to use some_eq_ex
   760 
   761 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   762 in this (rare) case use:
   763 
   764   delSWrapper "split_all_tac"
   765   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   766 
   767 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   768 MAY FAIL;
   769 
   770 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   771 Isabelle's type classes, ^ on functions and relations has too general
   772 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   773 necessary to attach explicit type constraints;
   774 
   775 * HOL/Relation: the prefix name of the infix "O" has been changed from
   776 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   777 renamed accordingly (eg "compI" -> "rel_compI").
   778 
   779 * HOL: syntax translations now work properly with numerals and records
   780 expressions;
   781 
   782 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   783 of "lam" -- INCOMPATIBILITY;
   784 
   785 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   786 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   787 renamed "Product_Type.unit";
   788 
   789 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   790 
   791 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   792 the "cases" method);
   793 
   794 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   795 Florian Kammüller);
   796 
   797 * HOL/IMP: updated and converted to new-style theory format; several
   798 parts turned into readable document, with proper Isar proof texts and
   799 some explanations (by Gerwin Klein);
   800 
   801 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   802 
   803 * HOL-Hyperreal is now a logic image;
   804 
   805 
   806 *** HOLCF ***
   807 
   808 * Isar: consts/constdefs supports mixfix syntax for continuous
   809 operations;
   810 
   811 * Isar: domain package adapted to new-style theory format, e.g. see
   812 HOLCF/ex/Dnat.thy;
   813 
   814 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
   815 potential INCOMPATIBILITY; now use plain induct_tac instead of former
   816 lift.induct_tac, always use UU instead of Undef;
   817 
   818 * HOLCF/IMP: updated and converted to new-style theory;
   819 
   820 
   821 *** ZF ***
   822 
   823 * Isar: proper integration of logic-specific tools and packages,
   824 including theory commands '(co)inductive', '(co)datatype',
   825 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
   826 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
   827 
   828 * theory Main no longer includes AC; for the Axiom of Choice, base
   829 your theory on Main_ZFC;
   830 
   831 * the integer library now covers quotients and remainders, with many
   832 laws relating division to addition, multiplication, etc.;
   833 
   834 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
   835 typeless version of the formalism;
   836 
   837 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
   838 format;
   839 
   840 * ZF/Induct: new directory for examples of inductive definitions,
   841 including theory Multiset for multiset orderings; converted to
   842 new-style theory format;
   843 
   844 * ZF: many new theorems about lists, ordinals, etc.;
   845 
   846 
   847 *** General ***
   848 
   849 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
   850 variable proof controls level of detail: 0 = no proofs (only oracle
   851 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
   852 also ref manual for further ML interfaces;
   853 
   854 * Pure/axclass: removed obsolete ML interface
   855 goal_subclass/goal_arity;
   856 
   857 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
   858 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
   859 separate tokens, so expressions involving minus need to be spaced
   860 properly;
   861 
   862 * Pure/syntax: support non-oriented infixes, using keyword "infix"
   863 rather than "infixl" or "infixr";
   864 
   865 * Pure/syntax: concrete syntax for dummy type variables admits genuine
   866 sort constraint specifications in type inference; e.g. "x::_::foo"
   867 ensures that the type of "x" is of sort "foo" (but not necessarily a
   868 type variable);
   869 
   870 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
   871 control output of nested => (types); the default behavior is
   872 "type_brackets";
   873 
   874 * Pure/syntax: builtin parse translation for "_constify" turns valued
   875 tokens into AST constants;
   876 
   877 * Pure/syntax: prefer later declarations of translations and print
   878 translation functions; potential INCOMPATIBILITY: need to reverse
   879 multiple declarations for same syntax element constant;
   880 
   881 * Pure/show_hyps reset by default (in accordance to existing Isar
   882 practice);
   883 
   884 * Provers/classical: renamed addaltern to addafter, addSaltern to
   885 addSafter;
   886 
   887 * Provers/clasimp: ``iff'' declarations now handle conditional rules
   888 as well;
   889 
   890 * system: tested support for MacOS X; should be able to get Isabelle +
   891 Proof General to work in a plain Terminal after installing Poly/ML
   892 (e.g. from the Isabelle distribution area) and GNU bash alone
   893 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
   894 support requires further installations, e.g. from
   895 http://fink.sourceforge.net/);
   896 
   897 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
   898 
   899 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
   900 of 40 MB), cf. ML_OPTIONS;
   901 
   902 * system: Proof General keywords specification is now part of the
   903 Isabelle distribution (see etc/isar-keywords.el);
   904 
   905 * system: support for persistent Proof General sessions (refrain from
   906 outdating all loaded theories on startup); user may create writable
   907 logic images like this: ``isabelle -q HOL Test'';
   908 
   909 * system: smart selection of Isabelle process versus Isabelle
   910 interface, accommodates case-insensitive file systems (e.g. HFS+); may
   911 run both "isabelle" and "Isabelle" even if file names are badly
   912 damaged (executable inspects the case of the first letter of its own
   913 name); added separate "isabelle-process" and "isabelle-interface";
   914 
   915 * system: refrain from any attempt at filtering input streams; no
   916 longer support ``8bit'' encoding of old isabelle font, instead proper
   917 iso-latin characters may now be used; the related isatools
   918 "symbolinput" and "nonascii" have disappeared as well;
   919 
   920 * system: removed old "xterm" interface (the print modes "xterm" and
   921 "xterm_color" are still available for direct use in a suitable
   922 terminal);
   923 
   924 
   925 
   926 New in Isabelle99-2 (February 2001)
   927 -----------------------------------
   928 
   929 *** Overview of INCOMPATIBILITIES ***
   930 
   931 * HOL: please note that theories in the Library and elsewhere often use the
   932 new-style (Isar) format; to refer to their theorems in an ML script you must
   933 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
   934 
   935 * HOL: inductive package no longer splits induction rule aggressively,
   936 but only as far as specified by the introductions given; the old
   937 format may be recovered via ML function complete_split_rule or attribute
   938 'split_rule (complete)';
   939 
   940 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
   941 gfp_Tarski to gfp_unfold;
   942 
   943 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
   944 
   945 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
   946 relation); infix "^^" has been renamed "``"; infix "``" has been
   947 renamed "`"; "univalent" has been renamed "single_valued";
   948 
   949 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
   950 operation;
   951 
   952 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
   953 
   954 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
   955 
   956 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
   957 consequence, it is no longer monotonic wrt. the local goal context
   958 (which is now passed through the inductive cases);
   959 
   960 * Document preparation: renamed standard symbols \<ll> to \<lless> and
   961 \<gg> to \<ggreater>;
   962 
   963 
   964 *** Document preparation ***
   965 
   966 * \isabellestyle{NAME} selects version of Isabelle output (currently
   967 available: are "it" for near math-mode best-style output, "sl" for
   968 slanted text style, and "tt" for plain type-writer; if no
   969 \isabellestyle command is given, output is according to slanted
   970 type-writer);
   971 
   972 * support sub/super scripts (for single symbols only), input syntax is
   973 like this: "A\<^sup>*" or "A\<^sup>\<star>";
   974 
   975 * some more standard symbols; see Appendix A of the system manual for
   976 the complete list of symbols defined in isabellesym.sty;
   977 
   978 * improved isabelle style files; more abstract symbol implementation
   979 (should now use \isamath{...} and \isatext{...} in custom symbol
   980 definitions);
   981 
   982 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
   983 state; Note that presentation of goal states does not conform to
   984 actual human-readable proof documents.  Please do not include goal
   985 states into document output unless you really know what you are doing!
   986 
   987 * proper indentation of antiquoted output with proportional LaTeX
   988 fonts;
   989 
   990 * no_document ML operator temporarily disables LaTeX document
   991 generation;
   992 
   993 * isatool unsymbolize tunes sources for plain ASCII communication;
   994 
   995 
   996 *** Isar ***
   997 
   998 * Pure: Isar now suffers initial goal statements to contain unbound
   999 schematic variables (this does not conform to actual readable proof
  1000 documents, due to unpredictable outcome and non-compositional proof
  1001 checking); users who know what they are doing may use schematic goals
  1002 for Prolog-style synthesis of proven results;
  1003 
  1004 * Pure: assumption method (an implicit finishing) now handles actual
  1005 rules as well;
  1006 
  1007 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
  1008 initial goal, declare "that" only as Pure intro (only for single
  1009 steps); the "that" rule assumption may now be involved in implicit
  1010 finishing, thus ".." becomes a feasible for trivial obtains;
  1011 
  1012 * Pure: default proof step now includes 'intro_classes'; thus trivial
  1013 instance proofs may be performed by "..";
  1014 
  1015 * Pure: ?thesis / ?this / "..." now work for pure meta-level
  1016 statements as well;
  1017 
  1018 * Pure: more robust selection of calculational rules;
  1019 
  1020 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
  1021 rule (as well as the assumption rule);
  1022 
  1023 * Pure: 'thm_deps' command visualizes dependencies of theorems and
  1024 lemmas, using the graph browser tool;
  1025 
  1026 * Pure: predict failure of "show" in interactive mode;
  1027 
  1028 * Pure: 'thms_containing' now takes actual terms as arguments;
  1029 
  1030 * HOL: improved method 'induct' --- now handles non-atomic goals
  1031 (potential INCOMPATIBILITY); tuned error handling;
  1032 
  1033 * HOL: cases and induct rules now provide explicit hints about the
  1034 number of facts to be consumed (0 for "type" and 1 for "set" rules);
  1035 any remaining facts are inserted into the goal verbatim;
  1036 
  1037 * HOL: local contexts (aka cases) may now contain term bindings as
  1038 well; the 'cases' and 'induct' methods new provide a ?case binding for
  1039 the result to be shown in each case;
  1040 
  1041 * HOL: added 'recdef_tc' command;
  1042 
  1043 * isatool convert assists in eliminating legacy ML scripts;
  1044 
  1045 
  1046 *** HOL ***
  1047 
  1048 * HOL/Library: a collection of generic theories to be used together
  1049 with main HOL; the theory loader path already includes this directory
  1050 by default; the following existing theories have been moved here:
  1051 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
  1052 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
  1053 
  1054 * HOL/Unix: "Some aspects of Unix file-system security", a typical
  1055 modelling and verification task performed in Isabelle/HOL +
  1056 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
  1057 
  1058 * HOL/Algebra: special summation operator SUM no longer exists, it has
  1059 been replaced by setsum; infix 'assoc' now has priority 50 (like
  1060 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
  1061 'domain', this makes the theory consistent with mathematical
  1062 literature;
  1063 
  1064 * HOL basics: added overloaded operations "inverse" and "divide"
  1065 (infix "/"), syntax for generic "abs" operation, generic summation
  1066 operator \<Sum>;
  1067 
  1068 * HOL/typedef: simplified package, provide more useful rules (see also
  1069 HOL/subset.thy);
  1070 
  1071 * HOL/datatype: induction rule for arbitrarily branching datatypes is
  1072 now expressed as a proper nested rule (old-style tactic scripts may
  1073 require atomize_strip_tac to cope with non-atomic premises);
  1074 
  1075 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
  1076 to "split_conv" (old name still available for compatibility);
  1077 
  1078 * HOL: improved concrete syntax for strings (e.g. allows translation
  1079 rules with string literals);
  1080 
  1081 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
  1082  and Fleuriot's mechanization of analysis, including the transcendental
  1083  functions for the reals;
  1084 
  1085 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
  1086 
  1087 
  1088 *** CTT ***
  1089 
  1090 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
  1091 "lam" is displayed as TWO lambda-symbols
  1092 
  1093 * CTT: theory Main now available, containing everything (that is, Bool
  1094 and Arith);
  1095 
  1096 
  1097 *** General ***
  1098 
  1099 * Pure: the Simplifier has been implemented properly as a derived rule
  1100 outside of the actual kernel (at last!); the overall performance
  1101 penalty in practical applications is about 50%, while reliability of
  1102 the Isabelle inference kernel has been greatly improved;
  1103 
  1104 * print modes "brackets" and "no_brackets" control output of nested =>
  1105 (types) and ==> (props); the default behaviour is "brackets";
  1106 
  1107 * Provers: fast_tac (and friends) now handle actual object-logic rules
  1108 as assumptions as well;
  1109 
  1110 * system: support Poly/ML 4.0;
  1111 
  1112 * system: isatool install handles KDE version 1 or 2;
  1113 
  1114 
  1115 
  1116 New in Isabelle99-1 (October 2000)
  1117 ----------------------------------
  1118 
  1119 *** Overview of INCOMPATIBILITIES ***
  1120 
  1121 * HOL: simplification of natural numbers is much changed; to partly
  1122 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
  1123 issue the following ML commands:
  1124 
  1125   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
  1126   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
  1127 
  1128 * HOL: simplification no longer dives into case-expressions; this is
  1129 controlled by "t.weak_case_cong" for each datatype t;
  1130 
  1131 * HOL: nat_less_induct renamed to less_induct;
  1132 
  1133 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
  1134 fixsome to patch .thy and .ML sources automatically;
  1135 
  1136   select_equality  -> some_equality
  1137   select_eq_Ex     -> some_eq_ex
  1138   selectI2EX       -> someI2_ex
  1139   selectI2         -> someI2
  1140   selectI          -> someI
  1141   select1_equality -> some1_equality
  1142   Eps_sym_eq       -> some_sym_eq_trivial
  1143   Eps_eq           -> some_eq_trivial
  1144 
  1145 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
  1146 
  1147 * HOL: removed obsolete theorem binding expand_if (refer to split_if
  1148 instead);
  1149 
  1150 * HOL: the recursion equations generated by 'recdef' are now called
  1151 f.simps instead of f.rules;
  1152 
  1153 * HOL: qed_spec_mp now also handles bounded ALL as well;
  1154 
  1155 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  1156 sometimes be needed;
  1157 
  1158 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  1159 
  1160 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  1161 
  1162 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  1163 product is now "<*>" instead of "Times"; the lexicographic product is
  1164 now "<*lex*>" instead of "**";
  1165 
  1166 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  1167 of main HOL, but was unused); better use HOL's datatype package;
  1168 
  1169 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  1170 the old syntax may be recovered as follows:
  1171 
  1172   syntax (symbols)
  1173     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  1174       (infixl "\\<oplus>" 100)
  1175 
  1176 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1177 
  1178 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1179 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1180 internally;
  1181 
  1182 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1183 changed from A/r to A//r;
  1184 
  1185 * ZF: new treatment of arithmetic (nat & int) may break some old
  1186 proofs;
  1187 
  1188 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1189 rulify -> rule_format, elimify -> elim_format, ...);
  1190 
  1191 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1192 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1193 should have to change intro!! to intro? only); replaced "delrule" by
  1194 "rule del";
  1195 
  1196 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1197 
  1198 * Provers: strengthened force_tac by using new first_best_tac;
  1199 
  1200 * LaTeX document preparation: several changes of isabelle.sty (see
  1201 lib/texinputs);
  1202 
  1203 
  1204 *** Document preparation ***
  1205 
  1206 * formal comments (text blocks etc.) in new-style theories may now
  1207 contain antiquotations of thm/prop/term/typ/text to be presented
  1208 according to latex print mode; concrete syntax is like this:
  1209 @{term[show_types] "f(x) = a + x"};
  1210 
  1211 * isatool mkdir provides easy setup of Isabelle session directories,
  1212 including proper document sources;
  1213 
  1214 * generated LaTeX sources are now deleted after successful run
  1215 (isatool document -c); may retain a copy somewhere else via -D option
  1216 of isatool usedir;
  1217 
  1218 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1219 style files, achieving self-contained LaTeX sources and simplifying
  1220 LaTeX debugging;
  1221 
  1222 * old-style theories now produce (crude) LaTeX output as well;
  1223 
  1224 * browser info session directories are now self-contained (may be put
  1225 on WWW server seperately); improved graphs of nested sessions; removed
  1226 graph for 'all sessions';
  1227 
  1228 * several improvements in isabelle style files; \isabellestyle{it}
  1229 produces fake math mode output; \isamarkupheader is now \section by
  1230 default; see lib/texinputs/isabelle.sty etc.;
  1231 
  1232 
  1233 *** Isar ***
  1234 
  1235 * Isar/Pure: local results and corresponding term bindings are now
  1236 subject to Hindley-Milner polymorphism (similar to ML); this
  1237 accommodates incremental type-inference very nicely;
  1238 
  1239 * Isar/Pure: new derived language element 'obtain' supports
  1240 generalized existence reasoning;
  1241 
  1242 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1243 support accumulation of results, without applying any rules yet;
  1244 useful to collect intermediate results without explicit name
  1245 references, and for use with transitivity rules with more than 2
  1246 premises;
  1247 
  1248 * Isar/Pure: scalable support for case-analysis type proofs: new
  1249 'case' language element refers to local contexts symbolically, as
  1250 produced by certain proof methods; internally, case names are attached
  1251 to theorems as "tags";
  1252 
  1253 * Isar/Pure: theory command 'hide' removes declarations from
  1254 class/type/const name spaces;
  1255 
  1256 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1257 indicate potential overloading;
  1258 
  1259 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1260 
  1261 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1262 "{a,b,c}" instead of {a,b,c};
  1263 
  1264 * Isar/Pure now provides its own version of intro/elim/dest
  1265 attributes; useful for building new logics, but beware of confusion
  1266 with the version in Provers/classical;
  1267 
  1268 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1269 case name 'antecedent';
  1270 
  1271 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1272 to the current context is now done automatically);
  1273 
  1274 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1275 for definining proof methods in ML;
  1276 
  1277 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1278 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1279 most cases, one should have to change intro!! to intro? only);
  1280 replaced "delrule" by "rule del";
  1281 
  1282 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1283 'symmetric' attribute (the latter supercedes [RS sym]);
  1284 
  1285 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1286 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1287 well (including splits);
  1288 
  1289 * Isar/Provers: Simplifier and Classical methods now support all kind
  1290 of modifiers used in the past, including 'cong', 'iff', etc.
  1291 
  1292 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1293 of Simplifier and Classical reasoner);
  1294 
  1295 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1296 now support named cases; major packages (inductive, datatype, primrec,
  1297 recdef) support case names and properly name parameters;
  1298 
  1299 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1300 monotonicity conditions are extracted to be proven at end of
  1301 calculations;
  1302 
  1303 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1304 method anyway;
  1305 
  1306 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1307 split_if split_if_asm; datatype package provides theorems foo.splits =
  1308 foo.split foo.split_asm for each datatype;
  1309 
  1310 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1311 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1312 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1313 use "(cases (simplified))" method in proper proof texts);
  1314 
  1315 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1316 
  1317 * Isar: names of theorems etc. may be natural numbers as well;
  1318 
  1319 * Isar: 'pr' command: optional arguments for goals_limit and
  1320 ProofContext.prems_limit; no longer prints theory contexts, but only
  1321 proof states;
  1322 
  1323 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1324 additional print modes to be specified; e.g. "pr(latex)" will print
  1325 proof state according to the Isabelle LaTeX style;
  1326 
  1327 * Isar: improved support for emulating tactic scripts, including proof
  1328 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1329 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1330 (for HOL datatypes);
  1331 
  1332 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1333 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1334 'proof method scripts' have to be in depth-first order;
  1335 
  1336 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1337 
  1338 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1339 should instead use individual commands for printing items
  1340 (print_commands, print_methods etc.);
  1341 
  1342 * Isar: added 'nothing' --- the empty list of theorems;
  1343 
  1344 
  1345 *** HOL ***
  1346 
  1347 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1348 corresponding virtual machine and a specification of its bytecode
  1349 verifier and a lightweight bytecode verifier, including proofs of
  1350 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1351 Cornelia Pusch (see also the homepage of project Bali at
  1352 http://isabelle.in.tum.de/Bali/);
  1353 
  1354 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1355 Clemens Ballarin;
  1356 
  1357 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1358 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1359 Rasmussen;
  1360 
  1361 * HOL/Lattice: fundamental concepts of lattice theory and order
  1362 structures, including duals, properties of bounds versus algebraic
  1363 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1364 Theorem for complete lattices etc.; may also serve as a demonstration
  1365 for abstract algebraic reasoning using axiomatic type classes, and
  1366 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1367 
  1368 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1369 von Oheimb;
  1370 
  1371 * HOL/IMPP: extension of IMP with local variables and mutually
  1372 recursive procedures, by David von Oheimb;
  1373 
  1374 * HOL/Lambda: converted into new-style theory and document;
  1375 
  1376 * HOL/ex/Multiquote: example of multiple nested quotations and
  1377 anti-quotations -- basically a generalized version of de-Bruijn
  1378 representation; very useful in avoiding lifting of operations;
  1379 
  1380 * HOL/record: added general record equality rule to simpset; fixed
  1381 select-update simplification procedure to handle extended records as
  1382 well; admit "r" as field name;
  1383 
  1384 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1385 other numeric types and also as the identity of groups, rings, etc.;
  1386 
  1387 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1388 Types nat and int belong to this axclass;
  1389 
  1390 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1391    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1392    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1393   two terms #m*u and #n*u are replaced by #(m+n)*u
  1394     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1395   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1396     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1397 
  1398 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1399 powerful prover for predicate logic but knows nothing of clasets; see
  1400 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1401 
  1402 * HOL: new version of "case_tac" subsumes both boolean case split and
  1403 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1404 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1405 
  1406 * HOL: simplification no longer dives into case-expressions: only the
  1407 selector expression is simplified, but not the remaining arms; to
  1408 enable full simplification of case-expressions for datatype t, you may
  1409 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1410 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1411 
  1412 * HOL/recdef: the recursion equations generated by 'recdef' for
  1413 function 'f' are now called f.simps instead of f.rules; if all
  1414 termination conditions are proved automatically, these simplification
  1415 rules are added to the simpset, as in primrec; rules may be named
  1416 individually as well, resulting in a separate list of theorems for
  1417 each equation;
  1418 
  1419 * HOL/While is a new theory that provides a while-combinator. It
  1420 permits the definition of tail-recursive functions without the
  1421 provision of a termination measure. The latter is necessary once the
  1422 invariant proof rule for while is applied.
  1423 
  1424 * HOL: new (overloaded) notation for the set of elements below/above
  1425 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1426 
  1427 * HOL: theorems impI, allI, ballI bound as "strip";
  1428 
  1429 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1430 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1431 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1432 
  1433 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1434 
  1435 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1436 main HOL, but was unused);
  1437 
  1438 * HOL: fewer consts declared as global (e.g. have to refer to
  1439 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1440 
  1441 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1442 in case of overlap with user translations (e.g. judgements over
  1443 tuples); (note that the underlying logical represenation is still
  1444 bogus);
  1445 
  1446 
  1447 *** ZF ***
  1448 
  1449 * ZF: simplification automatically cancels common terms in arithmetic
  1450 expressions over nat and int;
  1451 
  1452 * ZF: new treatment of nat to minimize type-checking: all operators
  1453 coerce their operands to a natural number using the function natify,
  1454 making the algebraic laws unconditional;
  1455 
  1456 * ZF: as above, for int: operators coerce their operands to an integer
  1457 using the function intify;
  1458 
  1459 * ZF: the integer library now contains many of the usual laws for the
  1460 orderings, including $<=, and monotonicity laws for $+ and $*;
  1461 
  1462 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1463 simplification;
  1464 
  1465 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1466 to the simplifier and classical reasoner simultaneously;
  1467 
  1468 
  1469 *** General ***
  1470 
  1471 * Provers: blast_tac now handles actual object-logic rules as
  1472 assumptions; note that auto_tac uses blast_tac internally as well;
  1473 
  1474 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1475 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1476 
  1477 * Provers: delrules now handles destruct rules as well (no longer need
  1478 explicit make_elim);
  1479 
  1480 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1481   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1482 use instead the strong form,
  1483   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1484 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1485 from destruct-rules;
  1486 
  1487 * Provers: Simplifier.easy_setup provides a fast path to basic
  1488 Simplifier setup for new object-logics;
  1489 
  1490 * Pure: AST translation rules no longer require constant head on LHS;
  1491 
  1492 * Pure: improved name spaces: ambiguous output is qualified; support
  1493 for hiding of names;
  1494 
  1495 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1496 XSYMBOL_HOME; no longer need to do manual configuration in most
  1497 situations;
  1498 
  1499 * system: compression of ML heaps images may now be controlled via -c
  1500 option of isabelle and isatool usedir (currently only observed by
  1501 Poly/ML);
  1502 
  1503 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1504 useful for remote X11);
  1505 
  1506 * system: provide TAGS file for Isabelle sources;
  1507 
  1508 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1509 order;
  1510 
  1511 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1512 timing flag supersedes proof_timing and Toplevel.trace;
  1513 
  1514 * ML: new combinators |>> and |>>> for incremental transformations
  1515 with secondary results (e.g. certain theory extensions):
  1516 
  1517 * ML: PureThy.add_defs gets additional argument to indicate potential
  1518 overloading (usually false);
  1519 
  1520 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1521 results;
  1522 
  1523 
  1524 
  1525 New in Isabelle99 (October 1999)
  1526 --------------------------------
  1527 
  1528 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1529 
  1530 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1531 are no longer simplified.  (This allows the simplifier to unfold recursive
  1532 functional programs.)  To restore the old behaviour, declare
  1533 
  1534     Delcongs [if_weak_cong];
  1535 
  1536 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1537 complement;
  1538 
  1539 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1540 
  1541 * HOL/datatype: mutual_induct_tac no longer exists --
  1542   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1543 
  1544 * HOL/typedef: fixed type inference for representing set; type
  1545 arguments now have to occur explicitly on the rhs as type constraints;
  1546 
  1547 * ZF: The con_defs part of an inductive definition may no longer refer
  1548 to constants declared in the same theory;
  1549 
  1550 * HOL, ZF: the function mk_cases, generated by the inductive
  1551 definition package, has lost an argument.  To simplify its result, it
  1552 uses the default simpset instead of a supplied list of theorems.
  1553 
  1554 * HOL/List: the constructors of type list are now Nil and Cons;
  1555 
  1556 * Simplifier: the type of the infix ML functions
  1557         setSSolver addSSolver setSolver addSolver
  1558 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1559 for packaging solvers. A solver is created via
  1560         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1561 where the string argument is only a comment.
  1562 
  1563 
  1564 *** Proof tools ***
  1565 
  1566 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1567 decision procedure for linear arithmetic. Currently it is used for
  1568 types `nat', `int', and `real' in HOL (see below); it can, should and
  1569 will be instantiated for other types and logics as well.
  1570 
  1571 * The simplifier now accepts rewrite rules with flexible heads, eg
  1572      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1573   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1574   matching.
  1575 
  1576 
  1577 *** General ***
  1578 
  1579 * New Isabelle/Isar subsystem provides an alternative to traditional
  1580 tactical theorem proving; together with the ProofGeneral/isar user
  1581 interface it offers an interactive environment for developing human
  1582 readable proof documents (Isar == Intelligible semi-automated
  1583 reasoning); for further information see isatool doc isar-ref,
  1584 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1585 
  1586 * improved and simplified presentation of theories: better HTML markup
  1587 (including colors), graph views in several sizes; isatool usedir now
  1588 provides a proper interface for user theories (via -P option); actual
  1589 document preparation based on (PDF)LaTeX is available as well (for
  1590 new-style theories only); see isatool doc system for more information;
  1591 
  1592 * native support for Proof General, both for classic Isabelle and
  1593 Isabelle/Isar;
  1594 
  1595 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1596 using the graph browser tool;
  1597 
  1598 * Isabelle manuals now also available as PDF;
  1599 
  1600 * theory loader rewritten from scratch (may not be fully
  1601 bug-compatible); old loadpath variable has been replaced by show_path,
  1602 add_path, del_path, reset_path functions; new operations such as
  1603 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1604 isatool doc ref);
  1605 
  1606 * improved isatool install: option -k creates KDE application icon,
  1607 option -p DIR installs standalone binaries;
  1608 
  1609 * added ML_PLATFORM setting (useful for cross-platform installations);
  1610 more robust handling of platform specific ML images for SML/NJ;
  1611 
  1612 * the settings environment is now statically scoped, i.e. it is never
  1613 created again in sub-processes invoked from isabelle, isatool, or
  1614 Isabelle;
  1615 
  1616 * path element specification '~~' refers to '$ISABELLE_HOME';
  1617 
  1618 * in locales, the "assumes" and "defines" parts may be omitted if
  1619 empty;
  1620 
  1621 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1622 long arrows);
  1623 
  1624 * new print_mode "HTML";
  1625 
  1626 * new flag show_tags controls display of tags of theorems (which are
  1627 basically just comments that may be attached by some tools);
  1628 
  1629 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1630 mode and goal output format:
  1631 
  1632 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1633 244c244
  1634 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1635 ---
  1636 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1637 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1638 181c181
  1639 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1640 ---
  1641 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1642 
  1643 * function bind_thms stores lists of theorems (cf. bind_thm);
  1644 
  1645 * new shorthand tactics ftac, eatac, datac, fatac;
  1646 
  1647 * qed (and friends) now accept "" as result name; in that case the
  1648 theorem is not stored, but proper checks and presentation of the
  1649 result still apply;
  1650 
  1651 * theorem database now also indexes constants "Trueprop", "all",
  1652 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1653 
  1654 
  1655 *** HOL ***
  1656 
  1657 ** HOL arithmetic **
  1658 
  1659 * There are now decision procedures for linear arithmetic over nat and
  1660 int:
  1661 
  1662 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1663 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1664 are treated as atomic; subformulae not involving type `nat' or `int'
  1665 are ignored; quantified subformulae are ignored unless they are
  1666 positive universal or negative existential. The tactic has to be
  1667 invoked by hand and can be a little bit slow. In particular, the
  1668 running time is exponential in the number of occurrences of `min' and
  1669 `max', and `-' on `nat'.
  1670 
  1671 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1672 (negated) (in)equalities among the premises and the conclusion into
  1673 account (i.e. no compound formulae) and does not know about `min' and
  1674 `max', and `-' on `nat'. It is fast and is used automatically by the
  1675 simplifier.
  1676 
  1677 NB: At the moment, these decision procedures do not cope with mixed
  1678 nat/int formulae where the two parts interact, such as `m < n ==>
  1679 int(m) < int(n)'.
  1680 
  1681 * HOL/Numeral provides a generic theory of numerals (encoded
  1682 efficiently as bit strings); setup for types nat/int/real is in place;
  1683 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1684 int, existing theories and proof scripts may require a few additional
  1685 type constraints;
  1686 
  1687 * integer division and remainder can now be performed on constant
  1688 arguments;
  1689 
  1690 * many properties of integer multiplication, division and remainder
  1691 are now available;
  1692 
  1693 * An interface to the Stanford Validity Checker (SVC) is available through the
  1694 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1695 are proved automatically.  SVC must be installed separately, and its results
  1696 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1697 invocation of the underlying oracle).  For SVC see
  1698   http://verify.stanford.edu/SVC
  1699 
  1700 * IsaMakefile: the HOL-Real target now builds an actual image;
  1701 
  1702 
  1703 ** HOL misc **
  1704 
  1705 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1706 (in Isabelle/Isar) -- by Gertrud Bauer;
  1707 
  1708 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1709 analysis for assembly languages with subtypes;
  1710 
  1711 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1712 -- avoids syntactic ambiguities and treats state, transition, and
  1713 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1714 changed syntax and (many) tactics;
  1715 
  1716 * HOL/inductive: Now also handles more general introduction rules such
  1717   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1718   theorems are now maintained within the theory (maintained via the
  1719   "mono" attribute);
  1720 
  1721 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1722   (using function types) such as
  1723 
  1724   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1725 
  1726 * HOL/record: record_simproc (part of the default simpset) takes care
  1727 of selectors applied to updated records; record_split_tac is no longer
  1728 part of the default claset; update_defs may now be removed from the
  1729 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1730 
  1731   claset_ref () := claset() addSWrapper record_split_wrapper;
  1732   Delsimprocs [record_simproc]
  1733 
  1734 * HOL/typedef: fixed type inference for representing set; type
  1735 arguments now have to occur explicitly on the rhs as type constraints;
  1736 
  1737 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1738 names rather than an ML expression;
  1739 
  1740 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1741 supplied later.  Program schemes can be defined, such as
  1742     "While B C s = (if B s then While B C (C s) else s)"
  1743 where the well-founded relation can be chosen after B and C have been given.
  1744 
  1745 * HOL/List: the constructors of type list are now Nil and Cons;
  1746 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1747 course, ML tools referring to List.list.op # etc. have to be adapted;
  1748 
  1749 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1750 disabled by default; run isabelle with option -m HOL to get back to
  1751 the original Gordon/HOL-style output;
  1752 
  1753 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1754 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1755 
  1756 * HOL basic syntax simplified (more orthogonal): all variants of
  1757 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1758 Eps operator is provided as well: "SOME x. P[x]";
  1759 
  1760 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1761 
  1762 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1763 thus available for user theories;
  1764 
  1765 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1766 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1767 time;
  1768 
  1769 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1770 several times and then mp;
  1771 
  1772 
  1773 *** LK ***
  1774 
  1775 * the notation <<...>> is now available as a notation for sequences of
  1776 formulas;
  1777 
  1778 * the simplifier is now installed
  1779 
  1780 * the axiom system has been generalized (thanks to Soren Heilmann)
  1781 
  1782 * the classical reasoner now has a default rule database
  1783 
  1784 
  1785 *** ZF ***
  1786 
  1787 * new primrec section allows primitive recursive functions to be given
  1788 directly (as in HOL) over datatypes and the natural numbers;
  1789 
  1790 * new tactics induct_tac and exhaust_tac for induction (or case
  1791 analysis) over datatypes and the natural numbers;
  1792 
  1793 * the datatype declaration of type T now defines the recursor T_rec;
  1794 
  1795 * simplification automatically does freeness reasoning for datatype
  1796 constructors;
  1797 
  1798 * automatic type-inference, with AddTCs command to insert new
  1799 type-checking rules;
  1800 
  1801 * datatype introduction rules are now added as Safe Introduction rules
  1802 to the claset;
  1803 
  1804 * the syntax "if P then x else y" is now available in addition to
  1805 if(P,x,y);
  1806 
  1807 
  1808 *** Internal programming interfaces ***
  1809 
  1810 * tuned simplifier trace output; new flag debug_simp;
  1811 
  1812 * structures Vartab / Termtab (instances of TableFun) offer efficient
  1813 tables indexed by indexname_ord / term_ord (compatible with aconv);
  1814 
  1815 * AxClass.axclass_tac lost the theory argument;
  1816 
  1817 * tuned current_goals_markers semantics: begin / end goal avoids
  1818 printing empty lines;
  1819 
  1820 * removed prs and prs_fn hook, which was broken because it did not
  1821 include \n in its semantics, forcing writeln to add one
  1822 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  1823 string -> unit if you really want to output text without newline;
  1824 
  1825 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  1826 plain output, interface builders may have to enable 'isabelle_font'
  1827 mode to get Isabelle font glyphs as before;
  1828 
  1829 * refined token_translation interface; INCOMPATIBILITY: output length
  1830 now of type real instead of int;
  1831 
  1832 * theory loader actions may be traced via new ThyInfo.add_hook
  1833 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  1834 your own database of information attached to *whole* theories -- as
  1835 opposed to intra-theory data slots offered via TheoryDataFun;
  1836 
  1837 * proper handling of dangling sort hypotheses (at last!);
  1838 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  1839 extra sort hypotheses that can be witnessed from the type signature;
  1840 the force_strip_shyps flag is gone, any remaining shyps are simply
  1841 left in the theorem (with a warning issued by strip_shyps_warning);
  1842 
  1843 
  1844 
  1845 New in Isabelle98-1 (October 1998)
  1846 ----------------------------------
  1847 
  1848 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1849 
  1850 * several changes of automated proof tools;
  1851 
  1852 * HOL: major changes to the inductive and datatype packages, including
  1853 some minor incompatibilities of theory syntax;
  1854 
  1855 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  1856 called `inj_on';
  1857 
  1858 * HOL: removed duplicate thms in Arith:
  1859   less_imp_add_less  should be replaced by  trans_less_add1
  1860   le_imp_add_le      should be replaced by  trans_le_add1
  1861 
  1862 * HOL: unary minus is now overloaded (new type constraints may be
  1863 required);
  1864 
  1865 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  1866 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  1867 now taken as an integer constant.
  1868 
  1869 * Pure: ML function 'theory_of' renamed to 'theory';
  1870 
  1871 
  1872 *** Proof tools ***
  1873 
  1874 * Simplifier:
  1875   1. Asm_full_simp_tac is now more aggressive.
  1876      1. It will sometimes reorient premises if that increases their power to
  1877         simplify.
  1878      2. It does no longer proceed strictly from left to right but may also
  1879         rotate premises to achieve further simplification.
  1880      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  1881      old Asm_full_simp_tac in that it does not rotate premises.
  1882   2. The simplifier now knows a little bit about nat-arithmetic.
  1883 
  1884 * Classical reasoner: wrapper mechanism for the classical reasoner now
  1885 allows for selected deletion of wrappers, by introduction of names for
  1886 wrapper functionals.  This implies that addbefore, addSbefore,
  1887 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  1888 and that adding two tactics with the same name overwrites the first
  1889 one (emitting a warning).
  1890   type wrapper = (int -> tactic) -> (int -> tactic)
  1891   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  1892   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  1893   delWrapper, delSWrapper: claset *  string            -> claset
  1894   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  1895 
  1896 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  1897 semantics; addbefore now affects only the unsafe part of step_tac
  1898 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  1899 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  1900 by Force_tac;
  1901 
  1902 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  1903 compWrapper; added safe wrapper (and access functions for it);
  1904 
  1905 * HOL/split_all_tac is now much faster and fails if there is nothing
  1906 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  1907 and the names of the automatically generated variables have changed.
  1908 split_all_tac has moved within claset() from unsafe wrappers to safe
  1909 wrappers, which means that !!-bound variables are split much more
  1910 aggressively, and safe_tac and clarify_tac now split such variables.
  1911 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  1912 Note: the same holds for record_split_tac, which does the job of
  1913 split_all_tac for record fields.
  1914 
  1915 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  1916 permanently to the default simpset using Addsplits just like
  1917 Addsimps. They can be removed via Delsplits just like
  1918 Delsimps. Lower-case versions are also available.
  1919 
  1920 * HOL/Simplifier: The rule split_if is now part of the default
  1921 simpset. This means that the simplifier will eliminate all occurrences
  1922 of if-then-else in the conclusion of a goal. To prevent this, you can
  1923 either remove split_if completely from the default simpset by
  1924 `Delsplits [split_if]' or remove it in a specific call of the
  1925 simplifier using `... delsplits [split_if]'.  You can also add/delete
  1926 other case splitting rules to/from the default simpset: every datatype
  1927 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  1928 t is the name of the datatype).
  1929 
  1930 * Classical reasoner / Simplifier combination: new force_tac (and
  1931 derivatives Force_tac, force) combines rewriting and classical
  1932 reasoning (and whatever other tools) similarly to auto_tac, but is
  1933 aimed to solve the given subgoal completely.
  1934 
  1935 
  1936 *** General ***
  1937 
  1938 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  1939 and `goalw': the theory is no longer needed as an explicit argument -
  1940 the current theory context is used; assumptions are no longer returned
  1941 at the ML-level unless one of them starts with ==> or !!; it is
  1942 recommended to convert to these new commands using isatool fixgoal
  1943 (backup your sources first!);
  1944 
  1945 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  1946 the current theory context, and 'theory' to lookup stored theories;
  1947 
  1948 * new theory section 'locale' for declaring constants, assumptions and
  1949 definitions that have local scope;
  1950 
  1951 * new theory section 'nonterminals' for purely syntactic types;
  1952 
  1953 * new theory section 'setup' for generic ML setup functions
  1954 (e.g. package initialization);
  1955 
  1956 * the distribution now includes Isabelle icons: see
  1957 lib/logo/isabelle-{small,tiny}.xpm;
  1958 
  1959 * isatool install - install binaries with absolute references to
  1960 ISABELLE_HOME/bin;
  1961 
  1962 * isatool logo -- create instances of the Isabelle logo (as EPS);
  1963 
  1964 * print mode 'emacs' reserved for Isamode;
  1965 
  1966 * support multiple print (ast) translations per constant name;
  1967 
  1968 * theorems involving oracles are now printed with a suffixed [!];
  1969 
  1970 
  1971 *** HOL ***
  1972 
  1973 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  1974 
  1975 * HOL/inductive package reorganized and improved: now supports mutual
  1976 definitions such as
  1977 
  1978   inductive EVEN ODD
  1979     intrs
  1980       null "0 : EVEN"
  1981       oddI "n : EVEN ==> Suc n : ODD"
  1982       evenI "n : ODD ==> Suc n : EVEN"
  1983 
  1984 new theorem list "elims" contains an elimination rule for each of the
  1985 recursive sets; inductive definitions now handle disjunctive premises
  1986 correctly (also ZF);
  1987 
  1988 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  1989 "mutual_induct" no longer exists - the induction rule is always
  1990 contained in "induct";
  1991 
  1992 
  1993 * HOL/datatype package re-implemented and greatly improved: now
  1994 supports mutually recursive datatypes such as
  1995 
  1996   datatype
  1997     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  1998             | SUM ('a aexp) ('a aexp)
  1999             | DIFF ('a aexp) ('a aexp)
  2000             | NUM 'a
  2001   and
  2002     'a bexp = LESS ('a aexp) ('a aexp)
  2003             | AND ('a bexp) ('a bexp)
  2004             | OR ('a bexp) ('a bexp)
  2005 
  2006 as well as indirectly recursive datatypes such as
  2007 
  2008   datatype
  2009     ('a, 'b) term = Var 'a
  2010                   | App 'b ((('a, 'b) term) list)
  2011 
  2012 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  2013 induction on mutually / indirectly recursive datatypes.
  2014 
  2015 Primrec equations are now stored in theory and can be accessed via
  2016 <function_name>.simps.
  2017 
  2018 INCOMPATIBILITIES:
  2019 
  2020   - Theories using datatypes must now have theory Datatype as an
  2021     ancestor.
  2022   - The specific <typename>.induct_tac no longer exists - use the
  2023     generic induct_tac instead.
  2024   - natE has been renamed to nat.exhaust - use exhaust_tac
  2025     instead of res_inst_tac ... natE. Note that the variable
  2026     names in nat.exhaust differ from the names in natE, this
  2027     may cause some "fragile" proofs to fail.
  2028   - The theorems split_<typename>_case and split_<typename>_case_asm
  2029     have been renamed to <typename>.split and <typename>.split_asm.
  2030   - Since default sorts of type variables are now handled correctly,
  2031     some datatype definitions may have to be annotated with explicit
  2032     sort constraints.
  2033   - Primrec definitions no longer require function name and type
  2034     of recursive argument.
  2035 
  2036 Consider using isatool fixdatatype to adapt your theories and proof
  2037 scripts to the new package (backup your sources first!).
  2038 
  2039 
  2040 * HOL/record package: considerably improved implementation; now
  2041 includes concrete syntax for record types, terms, updates; theorems
  2042 for surjective pairing and splitting !!-bound record variables; proof
  2043 support is as follows:
  2044 
  2045   1) standard conversions (selectors or updates applied to record
  2046 constructor terms) are part of the standard simpset;
  2047 
  2048   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  2049 made part of standard simpset and claset via addIffs;
  2050 
  2051   3) a tactic for record field splitting (record_split_tac) is part of
  2052 the standard claset (addSWrapper);
  2053 
  2054 To get a better idea about these rules you may retrieve them via
  2055 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  2056 the name of your record type.
  2057 
  2058 The split tactic 3) conceptually simplifies by the following rule:
  2059 
  2060   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  2061 
  2062 Thus any record variable that is bound by meta-all will automatically
  2063 blow up into some record constructor term, consequently the
  2064 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  2065 solve record problems automatically.
  2066 
  2067 
  2068 * reorganized the main HOL image: HOL/Integ and String loaded by
  2069 default; theory Main includes everything;
  2070 
  2071 * automatic simplification of integer sums and comparisons, using cancellation;
  2072 
  2073 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  2074 
  2075 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  2076 
  2077 * many new identities for unions, intersections, set difference, etc.;
  2078 
  2079 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  2080 called split_if, split_split, split_sum_case and split_nat_case (to go
  2081 with add/delsplits);
  2082 
  2083 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  2084 (?x::unit) = (); this is made part of the default simpset, which COULD
  2085 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  2086 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  2087 unit_abs_eta_conv is added in order to counter the effect of
  2088 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  2089 %u.f();
  2090 
  2091 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  2092 makes more sense);
  2093 
  2094 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2095   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2096   disjointness reasoning but breaking a few old proofs.
  2097 
  2098 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  2099 to 'converse' from 'inverse' (for compatibility with ZF and some
  2100 literature);
  2101 
  2102 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  2103 the well-founded relation;
  2104 
  2105 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  2106     Compl A.  The "Compl" syntax remains available as input syntax for this
  2107     release ONLY.
  2108 
  2109 * HOL/Update: new theory of function updates:
  2110     f(a:=b) == %x. if x=a then b else f x
  2111 may also be iterated as in f(a:=b,c:=d,...);
  2112 
  2113 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  2114 
  2115 * HOL/List:
  2116   - new function list_update written xs[i:=v] that updates the i-th
  2117     list position. May also be iterated as in xs[i:=a,j:=b,...].
  2118   - new function `upt' written [i..j(] which generates the list
  2119     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  2120     bound write [i..j], which is a shorthand for [i..j+1(].
  2121   - new lexicographic orderings and corresponding wellfoundedness theorems.
  2122 
  2123 * HOL/Arith:
  2124   - removed 'pred' (predecessor) function;
  2125   - generalized some theorems about n-1;
  2126   - many new laws about "div" and "mod";
  2127   - new laws about greatest common divisors (see theory ex/Primes);
  2128 
  2129 * HOL/Relation: renamed the relational operator r^-1 "converse"
  2130 instead of "inverse";
  2131 
  2132 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  2133   of the multiset ordering;
  2134 
  2135 * directory HOL/Real: a construction of the reals using Dedekind cuts
  2136   (not included by default);
  2137 
  2138 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  2139 
  2140 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  2141   programs, i.e. different program variables may have different types.
  2142 
  2143 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2144   [previously, this check worked only if the rewrite rule was unconditional]
  2145   Now rew can involve either definitions or equalities (either == or =).
  2146 
  2147 
  2148 *** ZF ***
  2149 
  2150 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  2151   only the theorems proved on ZF.ML;
  2152 
  2153 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2154   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2155   disjointness reasoning but breaking a few old proofs.
  2156 
  2157 * ZF/Update: new theory of function updates
  2158     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  2159   may also be iterated as in f(a:=b,c:=d,...);
  2160 
  2161 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  2162 
  2163 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2164   [previously, this check worked only if the rewrite rule was unconditional]
  2165   Now rew can involve either definitions or equalities (either == or =).
  2166 
  2167 * case_tac provided for compatibility with HOL
  2168     (like the old excluded_middle_tac, but with subgoals swapped)
  2169 
  2170 
  2171 *** Internal programming interfaces ***
  2172 
  2173 * Pure: several new basic modules made available for general use, see
  2174 also src/Pure/README;
  2175 
  2176 * improved the theory data mechanism to support encapsulation (data
  2177 kind name replaced by private Object.kind, acting as authorization
  2178 key); new type-safe user interface via functor TheoryDataFun; generic
  2179 print_data function becomes basically useless;
  2180 
  2181 * removed global_names compatibility flag -- all theory declarations
  2182 are qualified by default;
  2183 
  2184 * module Pure/Syntax now offers quote / antiquote translation
  2185 functions (useful for Hoare logic etc. with implicit dependencies);
  2186 see HOL/ex/Antiquote for an example use;
  2187 
  2188 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2189 cterm -> thm;
  2190 
  2191 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2192 subgoal;
  2193 
  2194 * Display.print_goals function moved to Locale.print_goals;
  2195 
  2196 * standard print function for goals supports current_goals_markers
  2197 variable for marking begin of proof, end of proof, start of goal; the
  2198 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2199 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2200 for example;
  2201 
  2202 
  2203 
  2204 New in Isabelle98 (January 1998)
  2205 --------------------------------
  2206 
  2207 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2208 
  2209 * changed lexical syntax of terms / types: dots made part of long
  2210 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2211 
  2212 * simpset (and claset) reference variable replaced by functions
  2213 simpset / simpset_ref;
  2214 
  2215 * no longer supports theory aliases (via merge) and non-trivial
  2216 implicit merge of thms' signatures;
  2217 
  2218 * most internal names of constants changed due to qualified names;
  2219 
  2220 * changed Pure/Sequence interface (see Pure/seq.ML);
  2221 
  2222 
  2223 *** General Changes ***
  2224 
  2225 * hierachically structured name spaces (for consts, types, axms, thms
  2226 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2227 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2228 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2229 long_names for fully qualified output names; NOTE: ML programs
  2230 (special tactics, packages etc.) referring to internal names may have
  2231 to be adapted to cope with fully qualified names; in case of severe
  2232 backward campatibility problems try setting 'global_names' at compile
  2233 time to have enrything declared within a flat name space; one may also
  2234 fine tune name declarations in theories via the 'global' and 'local'
  2235 section;
  2236 
  2237 * reimplemented the implicit simpset and claset using the new anytype
  2238 data filed in signatures; references simpset:simpset ref etc. are
  2239 replaced by functions simpset:unit->simpset and
  2240 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2241 to patch your ML files accordingly;
  2242 
  2243 * HTML output now includes theory graph data for display with Java
  2244 applet or isatool browser; data generated automatically via isatool
  2245 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2246 
  2247 * defs may now be conditional; improved rewrite_goals_tac to handle
  2248 conditional equations;
  2249 
  2250 * defs now admits additional type arguments, using TYPE('a) syntax;
  2251 
  2252 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2253 creates a new theory node; implicit merge of thms' signatures is
  2254 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2255 transfer:theory->thm->thm in (rare) cases;
  2256 
  2257 * improved handling of draft signatures / theories; draft thms (and
  2258 ctyps, cterms) are automatically promoted to real ones;
  2259 
  2260 * slightly changed interfaces for oracles: admit many per theory, named
  2261 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2262 
  2263 * print_goals: optional output of const types (set show_consts and
  2264 show_types);
  2265 
  2266 * improved output of warnings (###) and errors (***);
  2267 
  2268 * subgoal_tac displays a warning if the new subgoal has type variables;
  2269 
  2270 * removed old README and Makefiles;
  2271 
  2272 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2273 
  2274 * removed obsolete init_pps and init_database;
  2275 
  2276 * deleted the obsolete tactical STATE, which was declared by
  2277     fun STATE tacfun st = tacfun st st;
  2278 
  2279 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2280 (which abbreviates $HOME);
  2281 
  2282 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2283 use isatool fixseq to adapt your ML programs (this works for fully
  2284 qualified references to the Sequence structure only!);
  2285 
  2286 * use_thy no longer requires writable current directory; it always
  2287 reloads .ML *and* .thy file, if either one is out of date;
  2288 
  2289 
  2290 *** Classical Reasoner ***
  2291 
  2292 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2293 tactics that use classical reasoning to simplify a subgoal without
  2294 splitting it into several subgoals;
  2295 
  2296 * Safe_tac: like safe_tac but uses the default claset;
  2297 
  2298 
  2299 *** Simplifier ***
  2300 
  2301 * added simplification meta rules:
  2302     (asm_)(full_)simplify: simpset -> thm -> thm;
  2303 
  2304 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2305 logics (again);
  2306 
  2307 * added prems argument to simplification procedures;
  2308 
  2309 * HOL, FOL, ZF: added infix function `addsplits':
  2310   instead of `<simpset> setloop (split_tac <thms>)'
  2311   you can simply write `<simpset> addsplits <thms>'
  2312 
  2313 
  2314 *** Syntax ***
  2315 
  2316 * TYPE('a) syntax for type reflection terms;
  2317 
  2318 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2319 
  2320 * pretty printer: changed order of mixfix annotation preference (again!);
  2321 
  2322 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2323 
  2324 
  2325 *** HOL ***
  2326 
  2327 * HOL: 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 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2331 
  2332 * HOL/Auth: new protocol proofs including some for the Internet
  2333   protocol TLS;
  2334 
  2335 * HOL/Map: new theory of `maps' a la VDM;
  2336 
  2337 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2338 cancelling out common nat summands from =, <, <= (in)equalities, or
  2339 differences; simplification procedures nat_cancel_factor for
  2340 cancelling common factor from =, <, <= (in)equalities over natural
  2341 sums; nat_cancel contains both kinds of procedures, it is installed by
  2342 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2343 
  2344 * HOL/simplifier: terms of the form
  2345   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2346   are rewritten to
  2347   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2348   and those of the form
  2349   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2350   are rewritten to
  2351   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2352 
  2353 * HOL/datatype
  2354   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2355 
  2356   P(t_case f1 ... fn x) =
  2357      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2358         ...
  2359        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2360      )
  2361 
  2362   and a theorem `split_t_case_asm' of the form
  2363 
  2364   P(t_case f1 ... fn x) =
  2365     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2366         ...
  2367        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2368      )
  2369   which can be added to a simpset via `addsplits'. The existing theorems
  2370   expand_list_case and expand_option_case have been renamed to
  2371   split_list_case and split_option_case.
  2372 
  2373 * HOL/Arithmetic:
  2374   - `pred n' is automatically converted to `n-1'.
  2375     Users are strongly encouraged not to use `pred' any longer,
  2376     because it will disappear altogether at some point.
  2377   - Users are strongly encouraged to write "0 < n" rather than
  2378     "n ~= 0". Theorems and proof tools have been modified towards this
  2379     `standard'.
  2380 
  2381 * HOL/Lists:
  2382   the function "set_of_list" has been renamed "set" (and its theorems too);
  2383   the function "nth" now takes its arguments in the reverse order and
  2384   has acquired the infix notation "!" as in "xs!n".
  2385 
  2386 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2387 
  2388 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2389   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2390 
  2391 * HOL/record: extensible records with schematic structural subtyping
  2392 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2393 still lacks various theorems and concrete record syntax;
  2394 
  2395 
  2396 *** HOLCF ***
  2397 
  2398 * removed "axioms" and "generated by" sections;
  2399 
  2400 * replaced "ops" section by extended "consts" section, which is capable of
  2401   handling the continuous function space "->" directly;
  2402 
  2403 * domain package:
  2404   . proves theorems immediately and stores them in the theory,
  2405   . creates hierachical name space,
  2406   . now uses normal mixfix annotations (instead of cinfix...),
  2407   . minor changes to some names and values (for consistency),
  2408   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2409   . separator between mutual domain defs: changed "," to "and",
  2410   . improved handling of sort constraints;  now they have to
  2411     appear on the left-hand side of the equations only;
  2412 
  2413 * fixed LAM <x,y,zs>.b syntax;
  2414 
  2415 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2416 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2417 
  2418 
  2419 *** FOL and ZF ***
  2420 
  2421 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2422   with `addloop' of the simplifier to faciliate case splitting in premises.
  2423 
  2424 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2425 in HOL, they strip ALL and --> from proved theorems;
  2426 
  2427 
  2428 
  2429 New in Isabelle94-8 (May 1997)
  2430 ------------------------------
  2431 
  2432 *** General Changes ***
  2433 
  2434 * new utilities to build / run / maintain Isabelle etc. (in parts
  2435 still somewhat experimental); old Makefiles etc. still functional;
  2436 
  2437 * new 'Isabelle System Manual';
  2438 
  2439 * INSTALL text, together with ./configure and ./build scripts;
  2440 
  2441 * reimplemented type inference for greater efficiency, better error
  2442 messages and clean internal interface;
  2443 
  2444 * prlim command for dealing with lots of subgoals (an easier way of
  2445 setting goals_limit);
  2446 
  2447 
  2448 *** Syntax ***
  2449 
  2450 * supports alternative (named) syntax tables (parser and pretty
  2451 printer); internal interface is provided by add_modesyntax(_i);
  2452 
  2453 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2454 be used in conjunction with the Isabelle symbol font; uses the
  2455 "symbols" syntax table;
  2456 
  2457 * added token_translation interface (may translate name tokens in
  2458 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2459 the current print_mode); IMPORTANT: user print translation functions
  2460 are responsible for marking newly introduced bounds
  2461 (Syntax.mark_boundT);
  2462 
  2463 * token translations for modes "xterm" and "xterm_color" that display
  2464 names in bold, underline etc. or colors (which requires a color
  2465 version of xterm);
  2466 
  2467 * infixes may now be declared with names independent of their syntax;
  2468 
  2469 * added typed_print_translation (like print_translation, but may
  2470 access type of constant);
  2471 
  2472 
  2473 *** Classical Reasoner ***
  2474 
  2475 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2476 some limitations.  Blast_tac...
  2477   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2478   + ignores elimination rules that don't have the correct format
  2479         (the conclusion MUST be a formula variable)
  2480   + ignores types, which can make HOL proofs fail
  2481   + rules must not require higher-order unification, e.g. apply_type in ZF
  2482     [message "Function Var's argument not a bound variable" relates to this]
  2483   + its proof strategy is more general but can actually be slower
  2484 
  2485 * substitution with equality assumptions no longer permutes other
  2486 assumptions;
  2487 
  2488 * minor changes in semantics of addafter (now called addaltern); renamed
  2489 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2490 (and access functions for it);
  2491 
  2492 * improved combination of classical reasoner and simplifier:
  2493   + functions for handling clasimpsets
  2494   + improvement of addss: now the simplifier is called _after_ the
  2495     safe steps.
  2496   + safe variant of addss called addSss: uses safe simplifications
  2497     _during_ the safe steps. It is more complete as it allows multiple
  2498     instantiations of unknowns (e.g. with slow_tac).
  2499 
  2500 *** Simplifier ***
  2501 
  2502 * added interface for simplification procedures (functions that
  2503 produce *proven* rewrite rules on the fly, depending on current
  2504 redex);
  2505 
  2506 * ordering on terms as parameter (used for ordered rewriting);
  2507 
  2508 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2509 
  2510 * the solver is now split into a safe and an unsafe part.
  2511 This should be invisible for the normal user, except that the
  2512 functions setsolver and addsolver have been renamed to setSolver and
  2513 addSolver; added safe_asm_full_simp_tac;
  2514 
  2515 
  2516 *** HOL ***
  2517 
  2518 * a generic induction tactic `induct_tac' which works for all datatypes and
  2519 also for type `nat';
  2520 
  2521 * a generic case distinction tactic `exhaust_tac' which works for all
  2522 datatypes and also for type `nat';
  2523 
  2524 * each datatype comes with a function `size';
  2525 
  2526 * patterns in case expressions allow tuple patterns as arguments to
  2527 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2528 
  2529 * primrec now also works with type nat;
  2530 
  2531 * recdef: a new declaration form, allows general recursive functions to be
  2532 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2533 
  2534 * the constant for negation has been renamed from "not" to "Not" to
  2535 harmonize with FOL, ZF, LK, etc.;
  2536 
  2537 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2538 infinite lists;
  2539 
  2540 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2541 
  2542 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2543 problems in commutative rings, using axiomatic type classes for + and *;
  2544 
  2545 * more examples in HOL/MiniML and HOL/Auth;
  2546 
  2547 * more default rewrite rules for quantifiers, union/intersection;
  2548 
  2549 * a new constant `arbitrary == @x.False';
  2550 
  2551 * HOLCF/IOA replaces old HOL/IOA;
  2552 
  2553 * HOLCF changes: derived all rules and arities
  2554   + axiomatic type classes instead of classes
  2555   + typedef instead of faking type definitions
  2556   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2557   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2558   + eliminated the types void, one, tr
  2559   + use unit lift and bool lift (with translations) instead of one and tr
  2560   + eliminated blift from Lift3.thy (use Def instead of blift)
  2561   all eliminated rules are derived as theorems --> no visible changes ;
  2562 
  2563 
  2564 *** ZF ***
  2565 
  2566 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2567 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2568 as ZF_cs addSIs [equalityI];
  2569 
  2570 
  2571 
  2572 New in Isabelle94-7 (November 96)
  2573 ---------------------------------
  2574 
  2575 * allowing negative levels (as offsets) in prlev and choplev;
  2576 
  2577 * super-linear speedup for large simplifications;
  2578 
  2579 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2580 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2581 FAIL); can suppress it using the command Delsimps (ex_simps @
  2582 all_simps); De Morgan laws are also now included, by default;
  2583 
  2584 * improved printing of ==>  :  ~:
  2585 
  2586 * new object-logic "Sequents" adds linear logic, while replacing LK
  2587 and Modal (thanks to Sara Kalvala);
  2588 
  2589 * HOL/Auth: correctness proofs for authentication protocols;
  2590 
  2591 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2592 examples on HOL/Auth);
  2593 
  2594 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2595 the rewriter and classical reasoner simultaneously;
  2596 
  2597 * function uresult no longer returns theorems in "standard" format;
  2598 regain previous version by: val uresult = standard o uresult;
  2599 
  2600 
  2601 
  2602 New in Isabelle94-6
  2603 -------------------
  2604 
  2605 * oracles -- these establish an interface between Isabelle and trusted
  2606 external reasoners, which may deliver results as theorems;
  2607 
  2608 * proof objects (in particular record all uses of oracles);
  2609 
  2610 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2611 
  2612 * "constdefs" section in theory files;
  2613 
  2614 * "primrec" section (HOL) no longer requires names;
  2615 
  2616 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2617 
  2618 
  2619 
  2620 New in Isabelle94-5
  2621 -------------------
  2622 
  2623 * reduced space requirements;
  2624 
  2625 * automatic HTML generation from theories;
  2626 
  2627 * theory files no longer require "..." (quotes) around most types;
  2628 
  2629 * new examples, including two proofs of the Church-Rosser theorem;
  2630 
  2631 * non-curried (1994) version of HOL is no longer distributed;
  2632 
  2633 
  2634 
  2635 New in Isabelle94-4
  2636 -------------------
  2637 
  2638 * greatly reduced space requirements;
  2639 
  2640 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2641 
  2642 * searchable theorem database (see the section "Retrieving theorems" on
  2643 page 8 of the Reference Manual);
  2644 
  2645 * new examples, including Grabczewski's monumental case study of the
  2646 Axiom of Choice;
  2647 
  2648 * The previous version of HOL renamed to Old_HOL;
  2649 
  2650 * The new version of HOL (previously called CHOL) uses a curried syntax
  2651 for functions.  Application looks like f a b instead of f(a,b);
  2652 
  2653 * Mutually recursive inductive definitions finally work in HOL;
  2654 
  2655 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2656 translates to the operator "split";
  2657 
  2658 
  2659 
  2660 New in Isabelle94-3
  2661 -------------------
  2662 
  2663 * new infix operator, addss, allowing the classical reasoner to
  2664 perform simplification at each step of its search.  Example:
  2665         fast_tac (cs addss ss)
  2666 
  2667 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2668 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2669 look like (a,b) instead of <a,b>;
  2670 
  2671 * PLEASE NOTE: CHOL will eventually replace HOL!
  2672 
  2673 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2674 It translates to the operator "split".  A new theory of integers is available;
  2675 
  2676 * In ZF, integer numerals now denote two's-complement binary integers.
  2677 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2678 
  2679 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2680 of the Axiom of Choice;
  2681 
  2682 
  2683 
  2684 New in Isabelle94-2
  2685 -------------------
  2686 
  2687 * Significantly faster resolution;
  2688 
  2689 * the different sections in a .thy file can now be mixed and repeated
  2690 freely;
  2691 
  2692 * Database of theorems for FOL, HOL and ZF.  New
  2693 commands including qed, qed_goal and bind_thm store theorems in the database.
  2694 
  2695 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2696 a given theory (thms_of), or find out what theory a theorem was proved in
  2697 (theory_of_thm);
  2698 
  2699 * Bugs fixed in the inductive definition and datatype packages;
  2700 
  2701 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2702 and HOL_dup_cs obsolete;
  2703 
  2704 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2705 have been removed;
  2706 
  2707 * Simpler definition of function space in ZF;
  2708 
  2709 * new results about cardinal and ordinal arithmetic in ZF;
  2710 
  2711 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2712 types;
  2713 
  2714 
  2715 $Id$