NEWS
author ballarin
Fri Feb 11 10:03:41 2005 +0100 (2005-02-11)
changeset 15528 1b12557f720d
parent 15481 fc075ae929e4
child 15531 08c8dad8e399
permissions -rw-r--r--
New reference Toplevel.debug for verbose printing of exns.
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** General ***
     8 
     9 * Document preparation: new antiquotations @{lhs thm} and @{rhs thm}
    10   printing the lhs/rhs of definitions, equations, inequations etc. 
    11 
    12 * isatool usedir: new option -f that allows specification of the ML
    13   file to be used by Isabelle; default is ROOT.ML.
    14 
    15 * Theory headers: the new header syntax for Isar theories is
    16 
    17   theory <name>
    18   imports <theory1> ... <theoryn>
    19   begin
    20 
    21   optionally also with a "files" section. The syntax
    22 
    23   theory <name> = <theory1> + ... + <theoryn>:
    24 
    25   will still be supported for some time but will eventually disappear.
    26   The syntax of old-style theories has not changed.
    27 
    28 * Theory loader: parent theories can now also be referred to via
    29   relative and absolute paths.
    30 
    31 * Provers/quasi.ML:  new transitivity reasoners for transitivity only
    32   and quasi orders.
    33 
    34 * Provers/trancl.ML:  new transitivity reasoner for transitive and
    35   reflexive-transitive closure of relations.
    36 
    37 * Provers/blast.ML:  new reference depth_limit to make blast's depth
    38   limit (previously hard-coded with a value of 20) user-definable.
    39 
    40 * Provers: new version of the subst method, for single-step rewriting: it now
    41   works in bound variable contexts. New is subst (asm), for rewriting an
    42   assumption. Thanks to Lucas Dixon! INCOMPATIBILITY: may rewrite a different
    43   subterm than the original subst method, which is still available under the
    44   name simplesubst.
    45 
    46 * Pure: thin_tac now works even if the assumption being deleted contains !! or ==>. 
    47   More generally, erule now works even if the major premise of the elimination rule
    48   contains !! or ==>.
    49 
    50 * Pure: considerably improved version of 'constdefs' command.  Now
    51   performs automatic type-inference of declared constants; additional
    52   support for local structure declarations (cf. locales and HOL
    53   records), see also isar-ref manual.  Potential INCOMPATIBILITY: need
    54   to observe strictly sequential dependencies of definitions within a
    55   single 'constdefs' section; moreover, the declared name needs to be
    56   an identifier.  If all fails, consider to fall back on 'consts' and
    57   'defs' separately.
    58 
    59 * Pure: improved indexed syntax and implicit structures.  First of
    60   all, indexed syntax provides a notational device for subscripted
    61   application, using the new syntax \<^bsub>term\<^esub> for arbitrary
    62   expressions.  Secondly, in a local context with structure
    63   declarations, number indexes \<^sub>n or the empty index (default
    64   number 1) refer to a certain fixed variable implicitly; option
    65   show_structs controls printing of implicit structures.  Typical
    66   applications of these concepts involve record types and locales.
    67 
    68 * Pure: clear separation of logical types and nonterminals, where the
    69   latter may only occur in 'syntax' specifications or type
    70   abbreviations.  Before that distinction was only partially
    71   implemented via type class "logic" vs. "{}".  Potential
    72   INCOMPATIBILITY in rare cases of improper use of 'types'/'consts'
    73   instead of 'nonterminals'/'syntax'.  Some very exotic syntax
    74   specifications may require further adaption (e.g. Cube/Base.thy).
    75 
    76 * Pure: removed obsolete type class "logic", use the top sort {}
    77   instead.  Note that non-logical types should be declared as
    78   'nonterminals' rather than 'types'.  INCOMPATIBILITY for new
    79   object-logic specifications.
    80 
    81 * Pure: print_tac now outputs the goal through the trace channel.
    82 
    83 * Pure: reference Namespace.unique_names included.  If true the
    84   (shortest) namespace-prefix is printed to disambiguate conflicts (as
    85   yet). If false the first entry wins (as during parsing). Default
    86   value is true.
    87 
    88 * Pure: tuned internal renaming of symbolic identifiers -- attach
    89   primes instead of base 26 numbers.
    90 
    91 * Pure: new flag show_var_qmarks to control printing of leading
    92   question marks of variable names.
    93 
    94 * Pure/Syntax: inner syntax includes (*(*nested*) comments*).
    95 
    96 * Pure/Syntax: pretty pinter now supports unbreakable blocks,
    97   specified in mixfix annotations as "(00...)".
    98 
    99 * Pure/Syntax: 'advanced' translation functions (parse_translation
   100   etc.) may depend on the signature of the theory context being
   101   presently used for parsing/printing, see also isar-ref manual.
   102 
   103 * Pure/Simplifier: simplification procedures may now take the current
   104   simpset into account (cf. Simplifier.simproc(_i) / mk_simproc
   105   interface), which is very useful for calling the Simplifier
   106   recursively.  Minor INCOMPATIBILITY: the 'prems' argument of
   107   simprocs is gone -- use prems_of_ss on the simpset instead.
   108   Moreover, the low-level mk_simproc no longer applies Logic.varify
   109   internally, to allow for use in a context of fixed variables.
   110 
   111 * Pure/Simplifier: Command "find_rewrites" takes a string and lists all
   112   equality theorems (not just those with attribute simp!) whose left-hand
   113   side matches the term given via the string. In PG the command can be
   114   activated via Isabelle -> Show me -> matching rewrites.
   115 
   116 * Provers: Simplifier and Classical Reasoner now support proof context
   117   dependent plug-ins (simprocs, solvers, wrappers etc.).  These extra
   118   components are stored in the theory and patched into the
   119   simpset/claset when used in an Isar proof context.  Context
   120   dependent components are maintained by the following theory
   121   operations:
   122 
   123     Simplifier.add_context_simprocs
   124     Simplifier.del_context_simprocs
   125     Simplifier.set_context_subgoaler
   126     Simplifier.reset_context_subgoaler
   127     Simplifier.add_context_looper
   128     Simplifier.del_context_looper
   129     Simplifier.add_context_unsafe_solver
   130     Simplifier.add_context_safe_solver
   131 
   132     Classical.add_context_safe_wrapper
   133     Classical.del_context_safe_wrapper
   134     Classical.add_context_unsafe_wrapper
   135     Classical.del_context_unsafe_wrapper
   136 
   137   IMPORTANT NOTE: proof tools (methods etc.) need to use
   138   local_simpset_of and local_claset_of to instead of the primitive
   139   Simplifier.get_local_simpset and Classical.get_local_claset,
   140   respectively, in order to see the context dependent fields!
   141 
   142 * Document preparation: antiquotations now provide the option
   143   'locale=NAME' to specify an alternative context used for evaluating
   144   and printing the subsequent argument, as in @{thm [locale=LC]
   145   fold_commute}, for example.
   146 
   147 * Document preparation: commands 'display_drafts' and 'print_drafts'
   148   perform simple output of raw sources.  Only those symbols that do
   149   not require additional LaTeX packages (depending on comments in
   150   isabellesym.sty) are displayed properly, everything else is left
   151   verbatim.  We use isatool display and isatool print as front ends;
   152   these are subject to the DVI_VIEWER and PRINT_COMMAND settings,
   153   respectively.
   154 
   155 * Document preparation: Proof scripts as well as some other commands
   156   such as ML or parse/print_translation can now be hidden in the document.
   157   Hiding is enabled by default, and can be disabled either via the option
   158   '-H false' of isatool usedir or by resetting the reference variable
   159   IsarOutput.hide_commands. Additional commands to be hidden may be
   160   declared using IsarOutput.add_hidden_commands.
   161 
   162 * ML: output via the Isabelle channels of writeln/warning/error
   163   etc. is now passed through Output.output, with a hook for arbitrary
   164   transformations depending on the print_mode (cf. Output.add_mode --
   165   the first active mode that provides a output function wins).
   166   Already formatted output may be embedded into further text via
   167   Output.raw; the result of Pretty.string_of/str_of and derived
   168   functions (string_of_term/cterm/thm etc.) is already marked raw to
   169   accommodate easy composition of diagnostic messages etc.
   170   Programmers rarely need to care about Output.output or Output.raw at
   171   all, with some notable exceptions: Output.output is required when
   172   bypassing the standard channels (writeln etc.), or in token
   173   translations to produce properly formatted results; Output.raw is
   174   required when capturing already output material that will eventually
   175   be presented to the user a second time.  For the default print mode,
   176   both Output.output and Output.raw have no effect.
   177 
   178 
   179 *** Isar ***
   180 
   181 * Debugging: new reference Toplevel.debug; default false.
   182   Set to make printing of exceptions THM, TERM, TYPE and THEORY more verbose.
   183   
   184 * Locales:
   185   - "includes" disallowed in declaration of named locales (command "locale").
   186   - Fixed parameter management in theorem generation for goals with "includes".
   187     INCOMPATIBILITY: rarely, the generated theorem statement is different.
   188 
   189 * New syntax
   190 
   191     <theorem_name> (<index>, ..., <index>-<index>, ...)
   192 
   193   for referring to specific theorems in a named list of theorems via
   194   indices.
   195 
   196 *** HOL ***
   197 
   198 * Datatype induction via method `induct' now preserves the name of the
   199   induction variable. For example, when proving P(xs::'a list) by induction
   200   on xs, the induction step is now P(xs) ==> P(a#xs) rather than
   201   P(list) ==> P(a#list) as previously.
   202 
   203 * HOL/record: reimplementation of records. Improved scalability for
   204   records with many fields, avoiding performance problems for type
   205   inference. Records are no longer composed of nested field types, but
   206   of nested extension types. Therefore the record type only grows
   207   linear in the number of extensions and not in the number of fields.
   208   The top-level (users) view on records is preserved.  Potential
   209   INCOMPATIBILITY only in strange cases, where the theory depends on
   210   the old record representation. The type generated for a record is
   211   called <record_name>_ext_type.
   212 
   213 * HOL/record: Reference record_quick_and_dirty_sensitive can be
   214   enabled to skip the proofs triggered by a record definition or a
   215   simproc (if quick_and_dirty is enabled). Definitions of large
   216   records can take quite long.
   217 
   218 * HOL/record: "record_upd_simproc" for simplification of multiple
   219   record updates enabled by default.  Moreover, trivial updates are
   220   also removed: r(|x := x r|) = r.  INCOMPATIBILITY: old proofs break
   221   occasionally, since simplification is more powerful by default.
   222 
   223 * HOL: symbolic syntax of Hilbert Choice Operator is now as follows:
   224 
   225   syntax (epsilon)
   226     "_Eps" :: "[pttrn, bool] => 'a"    ("(3\<some>_./ _)" [0, 10] 10)
   227 
   228   The symbol \<some> is displayed as the alternative epsilon of LaTeX
   229   and x-symbol; use option '-m epsilon' to get it actually printed.
   230   Moreover, the mathematically important symbolic identifier
   231   \<epsilon> becomes available as variable, constant etc.
   232 
   233 * HOL: "x > y" abbreviates "y < x" and "x >= y" abbreviates "y <= x".
   234   Similarly for all quantifiers: "ALL x > y" etc.
   235   The x-symbol for >= is \<ge>.
   236 
   237 * HOL/SetInterval: The syntax for open intervals has changed:
   238 
   239   Old         New
   240   {..n(}   -> {..<n}
   241   {)n..}   -> {n<..}
   242   {m..n(}  -> {m..<n}
   243   {)m..n}  -> {m<..n}
   244   {)m..n(} -> {m<..<n}
   245 
   246   The old syntax is still supported but will disappear in the future.
   247   For conversion use the following emacs search and replace patterns:
   248 
   249   {)\([^\.]*\)\.\.  ->  {\1<\.\.}
   250   \.\.\([^(}]*\)(}  ->  \.\.<\1}
   251 
   252   They are not perfect but work quite well.
   253 
   254 * HOL: The syntax for 'setsum', summation over finite sets, has changed:
   255 
   256   The syntax for 'setsum (%x. e) A' used to be '\<Sum>x:A. e'
   257   and is now either 'SUM x:A. e' or '\<Sum>x\<in>A. e'.
   258 
   259   There is new syntax for summation over finite sets:
   260 
   261   '\<Sum>x | P. e'    is the same as  'setsum (%x. e) {x. P}'
   262   '\<Sum>x=a..b. e'   is the same as  'setsum (%x. e) {a..b}'
   263   '\<Sum>x=a..<b. e'  is the same as  'setsum (%x. e) {a..<b}'
   264   '\<Sum>x<k. e'      is the same as  'setsum (%x. e) {..<k}'
   265 
   266   Function 'Summation' over nat is gone, its syntax '\<Sum>i<k. e'
   267   now translates into 'setsum' as above.
   268 
   269 * HOL: Finite set induction: In Isar proofs, the insert case is now
   270   "case (insert x F)" instead of the old counterintuitive "case (insert F x)".
   271 
   272 * HOL/Simplifier:
   273 
   274   - Is now set up to reason about transitivity chains involving "trancl"
   275   (r^+) and "rtrancl" (r^*) by setting up tactics provided by
   276   Provers/trancl.ML as additional solvers.  INCOMPATIBILITY: old proofs break
   277   occasionally as simplification may now solve more goals than previously.
   278 
   279   - Converts x <= y into x = y if assumption y <= x is present.  Works for
   280   all partial orders (class "order"), in particular numbers and sets. For
   281   linear orders (e.g. numbers) it treats ~ x < y just like y <= x.
   282 
   283   - Simproc for "let x = a in f x"
   284   If a is a free or bound variable or a constant then the let is unfolded.
   285   Otherwise first a is simplified to a', and then f a' is simplified to
   286   g. If possible we abstract a' from g arriving at "let x = a' in g' x",
   287   otherwise we unfold the let and arrive at g. The simproc can be 
   288   enabled/disabled by the reference use_let_simproc. Potential
   289   INCOMPATIBILITY since simplification is more powerful by default.
   290  
   291 * HOL: new 'isatool dimacs2hol' to convert files in DIMACS CNF format
   292   (containing Boolean satisfiability problems) into Isabelle/HOL theories.
   293 
   294 
   295 *** HOLCF ***
   296 
   297 * HOLCF: discontinued special version of 'constdefs' (which used to
   298   support continuous functions) in favor of the general Pure one with
   299   full type-inference.
   300 
   301 
   302 *** ZF ***
   303 
   304 * ZF/ex/{Group,Ring}: examples in abstract algebra, including the
   305   First Isomorphism Theorem (on quotienting by the kernel of a
   306   homomorphism).
   307 
   308 * ZF/Simplifier: install second copy of type solver that actually
   309   makes use of TC rules declared to Isar proof contexts (or locales);
   310   the old version is still required for ML proof scripts.
   311 
   312 
   313 
   314 New in Isabelle2004 (April 2004)
   315 --------------------------------
   316 
   317 *** General ***
   318 
   319 * Provers/order.ML:  new efficient reasoner for partial and linear orders.
   320   Replaces linorder.ML.
   321 
   322 * Pure: Greek letters (except small lambda, \<lambda>), as well as Gothic
   323   (\<aa>...\<zz>\<AA>...\<ZZ>), calligraphic (\<A>...\<Z>), and Euler
   324   (\<a>...\<z>), are now considered normal letters, and can therefore
   325   be used anywhere where an ASCII letter (a...zA...Z) has until
   326   now. COMPATIBILITY: This obviously changes the parsing of some
   327   terms, especially where a symbol has been used as a binder, say
   328   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed
   329   as an identifier.  Fix it by inserting a space around former
   330   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in
   331   existing theory and ML files.
   332 
   333 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.
   334 
   335 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now
   336   allowed in identifiers. Similar to Greek letters \<^isub> is now considered
   337   a normal (but invisible) letter. For multiple letter subscripts repeat
   338   \<^isub> like this: x\<^isub>1\<^isub>2.
   339 
   340 * Pure: There are now sub-/superscripts that can span more than one
   341   character. Text between \<^bsub> and \<^esub> is set in subscript in
   342   ProofGeneral and LaTeX, text between \<^bsup> and \<^esup> in
   343   superscript. The new control characters are not identifier parts.
   344 
   345 * Pure: Control-symbols of the form \<^raw:...> will literally print the
   346   content of "..." to the latex file instead of \isacntrl... . The "..."
   347   may consist of any printable characters excluding the end bracket >.
   348 
   349 * Pure: Using new Isar command "finalconsts" (or the ML functions
   350   Theory.add_finals or Theory.add_finals_i) it is now possible to
   351   declare constants "final", which prevents their being given a definition
   352   later.  It is useful for constants whose behaviour is fixed axiomatically
   353   rather than definitionally, such as the meta-logic connectives.
   354 
   355 * Pure: 'instance' now handles general arities with general sorts
   356   (i.e. intersections of classes),
   357 
   358 * Presentation: generated HTML now uses a CSS style sheet to make layout
   359   (somewhat) independent of content. It is copied from lib/html/isabelle.css.
   360   It can be changed to alter the colors/layout of generated pages.
   361 
   362 
   363 *** Isar ***
   364 
   365 * Tactic emulation methods rule_tac, erule_tac, drule_tac, frule_tac,
   366   cut_tac, subgoal_tac and thin_tac:
   367   - Now understand static (Isar) contexts.  As a consequence, users of Isar
   368     locales are no longer forced to write Isar proof scripts.
   369     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
   370     emulations.
   371   - INCOMPATIBILITY: names of variables to be instantiated may no
   372     longer be enclosed in quotes.  Instead, precede variable name with `?'.
   373     This is consistent with the instantiation attribute "where".
   374 
   375 * Attributes "where" and "of":
   376   - Now take type variables of instantiated theorem into account when reading
   377     the instantiation string.  This fixes a bug that caused instantiated
   378     theorems to have too special types in some circumstances.
   379   - "where" permits explicit instantiations of type variables.
   380 
   381 * Calculation commands "moreover" and "also" no longer interfere with
   382   current facts ("this"), admitting arbitrary combinations with "then"
   383   and derived forms.
   384 
   385 * Locales:
   386   - Goal statements involving the context element "includes" no longer
   387     generate theorems with internal delta predicates (those ending on
   388     "_axioms") in the premise.
   389     Resolve particular premise with <locale>.intro to obtain old form.
   390   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
   391     specification and "includes" elements in goal statement.
   392   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
   393     [intro?] and [elim?] (respectively) by default.
   394   - Experimental command for instantiation of locales in proof contexts:
   395         instantiate <label>[<attrs>]: <loc>
   396     Instantiates locale <loc> and adds all its theorems to the current context
   397     taking into account their attributes.  Label and attrs are optional
   398     modifiers, like in theorem declarations.  If present, names of
   399     instantiated theorems are qualified with <label>, and the attributes
   400     <attrs> are applied after any attributes these theorems might have already.
   401       If the locale has assumptions, a chained fact of the form
   402     "<loc> t1 ... tn" is expected from which instantiations of the parameters
   403     are derived.  The command does not support old-style locales declared
   404     with "locale (open)".
   405       A few (very simple) examples can be found in FOL/ex/LocaleInst.thy.
   406 
   407 * HOL: Tactic emulation methods induct_tac and case_tac understand static
   408   (Isar) contexts.
   409 
   410 
   411 *** HOL ***
   412 
   413 * Proof import: new image HOL4 contains the imported library from
   414   the HOL4 system with about 2500 theorems. It is imported by
   415   replaying proof terms produced by HOL4 in Isabelle. The HOL4 image
   416   can be used like any other Isabelle image.  See
   417   HOL/Import/HOL/README for more information.
   418 
   419 * Simplifier:
   420   - Much improved handling of linear and partial orders.
   421     Reasoners for linear and partial orders are set up for type classes
   422     "linorder" and "order" respectively, and are added to the default simpset
   423     as solvers.  This means that the simplifier can build transitivity chains
   424     to solve goals from the assumptions.
   425   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications
   426     of blast or auto after simplification become unnecessary because the goal
   427     is solved by simplification already.
   428 
   429 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws,
   430     all proved in axiomatic type classes for semirings, rings and fields.
   431 
   432 * Numerics:
   433   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are
   434     now formalized using the Ring_and_Field theory mentioned above.
   435   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently
   436     than before, because now they are set up once in a generic manner.
   437   - INCOMPATIBILITY: many type-specific arithmetic laws have gone.
   438     Look for the general versions in Ring_and_Field (and Power if they concern
   439     exponentiation).
   440 
   441 * Type "rat" of the rational numbers is now available in HOL-Complex.
   442 
   443 * Records:
   444   - Record types are now by default printed with their type abbreviation
   445     instead of the list of all field types. This can be configured via
   446     the reference "print_record_type_abbr".
   447   - Simproc "record_upd_simproc" for simplification of multiple updates added
   448     (not enabled by default).
   449   - Simproc "record_ex_sel_eq_simproc" to simplify EX x. sel r = x resp.
   450     EX x. x = sel r to True (not enabled by default).
   451   - Tactic "record_split_simp_tac" to split and simplify records added.
   452 
   453 * 'specification' command added, allowing for definition by
   454   specification.  There is also an 'ax_specification' command that
   455   introduces the new constants axiomatically.
   456 
   457 * arith(_tac) is now able to generate counterexamples for reals as well.
   458 
   459 * HOL-Algebra: new locale "ring" for non-commutative rings.
   460 
   461 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
   462   definitions, thanks to Sava Krsti\'{c} and John Matthews.
   463 
   464 * HOL-Matrix: a first theory for matrices in HOL with an application of
   465   matrix theory to linear programming.
   466 
   467 * Unions and Intersections:
   468   The latex output syntax of UN and INT has been changed
   469   from "\Union x \in A. B" to "\Union_{x \in A} B"
   470   i.e. the index formulae has become a subscript.
   471   Similarly for "\Union x. B", and for \Inter instead of \Union.
   472 
   473 * Unions and Intersections over Intervals:
   474   There is new short syntax "UN i<=n. A" for "UN i:{0..n}. A". There is
   475   also an x-symbol version with subscripts "\<Union>\<^bsub>i <= n\<^esub>. A"
   476   like in normal math, and corresponding versions for < and for intersection.
   477 
   478 * ML: the legacy theory structures Int and List have been removed. They had
   479   conflicted with ML Basis Library structures having the same names.
   480 
   481 * 'refute' command added to search for (finite) countermodels.  Only works
   482   for a fragment of HOL.  The installation of an external SAT solver is
   483   highly recommended.  See "HOL/Refute.thy" for details.
   484 
   485 * 'quickcheck' command: Allows to find counterexamples by evaluating
   486   formulae under an assignment of free variables to random values.
   487   In contrast to 'refute', it can deal with inductive datatypes,
   488   but cannot handle quantifiers. See "HOL/ex/Quickcheck_Examples.thy"
   489   for examples.
   490 
   491 
   492 *** HOLCF ***
   493 
   494 * Streams now come with concatenation and are part of the HOLCF image
   495 
   496 
   497 
   498 New in Isabelle2003 (May 2003)
   499 ------------------------------
   500 
   501 *** General ***
   502 
   503 * Provers/simplifier:
   504 
   505   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   506     Assumptions are now subject to complete mutual simplification,
   507     not just from left to right. The simplifier now preserves
   508     the order of assumptions.
   509 
   510     Potential INCOMPATIBILITY:
   511 
   512     -- simp sometimes diverges where the old version did
   513        not, e.g. invoking simp on the goal
   514 
   515         [| P (f x); y = x; f x = f y |] ==> Q
   516 
   517        now gives rise to the infinite reduction sequence
   518 
   519         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   520 
   521        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   522        kind of problem.
   523 
   524     -- Tactics combining classical reasoner and simplification (such as auto)
   525        are also affected by this change, because many of them rely on
   526        simp. They may sometimes diverge as well or yield a different numbers
   527        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   528        in case of problems. Sometimes subsequent calls to the classical
   529        reasoner will fail because a preceeding call to the simplifier too
   530        eagerly simplified the goal, e.g. deleted redundant premises.
   531 
   532   - The simplifier trace now shows the names of the applied rewrite rules
   533 
   534   - You can limit the number of recursive invocations of the simplifier
   535     during conditional rewriting (where the simplifie tries to solve the
   536     conditions before applying the rewrite rule):
   537     ML "simp_depth_limit := n"
   538     where n is an integer. Thus you can force termination where previously
   539     the simplifier would diverge.
   540 
   541   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   542 
   543   - No longer aborts on failed congruence proof.  Instead, the
   544     congruence is ignored.
   545 
   546 * Pure: New generic framework for extracting programs from constructive
   547   proofs. See HOL/Extraction.thy for an example instantiation, as well
   548   as HOL/Extraction for some case studies.
   549 
   550 * Pure: The main goal of the proof state is no longer shown by default, only
   551 the subgoals. This behaviour is controlled by a new flag.
   552    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   553 (ML: Proof.show_main_goal).
   554 
   555 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   556 rules whose conclusion matches subgoal 1:
   557       PG menu: Isabelle/Isar -> Show me -> matching rules
   558 The rules are ordered by how closely they match the subgoal.
   559 In particular, rules that solve a subgoal outright are displayed first
   560 (or rather last, the way they are printed).
   561 (ML: ProofGeneral.print_intros())
   562 
   563 * Pure: New flag trace_unify_fail causes unification to print
   564 diagnostic information (PG: in trace buffer) when it fails. This is
   565 useful for figuring out why single step proofs like rule, erule or
   566 assumption failed.
   567 
   568 * Pure: Locale specifications now produce predicate definitions
   569 according to the body of text (covering assumptions modulo local
   570 definitions); predicate "loc_axioms" covers newly introduced text,
   571 while "loc" is cumulative wrt. all included locale expressions; the
   572 latter view is presented only on export into the global theory
   573 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   574 on the old view without predicates;
   575 
   576 * Pure: predefined locales "var" and "struct" are useful for sharing
   577 parameters (as in CASL, for example); just specify something like
   578 ``var x + var y + struct M'' as import;
   579 
   580 * Pure: improved thms_containing: proper indexing of facts instead of
   581 raw theorems; check validity of results wrt. current name space;
   582 include local facts of proof configuration (also covers active
   583 locales), cover fixed variables in index; may use "_" in term
   584 specification; an optional limit for the number of printed facts may
   585 be given (the default is 40);
   586 
   587 * Pure: disallow duplicate fact bindings within new-style theory files
   588 (batch-mode only);
   589 
   590 * Provers: improved induct method: assumptions introduced by case
   591 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   592 the goal statement); "foo" still refers to all facts collectively;
   593 
   594 * Provers: the function blast.overloaded has been removed: all constants
   595 are regarded as potentially overloaded, which improves robustness in exchange
   596 for slight decrease in efficiency;
   597 
   598 * Provers/linorder: New generic prover for transitivity reasoning over
   599 linear orders.  Note: this prover is not efficient!
   600 
   601 * Isar: preview of problems to finish 'show' now produce an error
   602 rather than just a warning (in interactive mode);
   603 
   604 
   605 *** HOL ***
   606 
   607 * arith(_tac)
   608 
   609  - Produces a counter example if it cannot prove a goal.
   610    Note that the counter example may be spurious if the goal is not a formula
   611    of quantifier-free linear arithmetic.
   612    In ProofGeneral the counter example appears in the trace buffer.
   613 
   614  - Knows about div k and mod k where k is a numeral of type nat or int.
   615 
   616  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   617    linear arithmetic fails. This takes account of quantifiers and divisibility.
   618    Presburger arithmetic can also be called explicitly via presburger(_tac).
   619 
   620 * simp's arithmetic capabilities have been enhanced a bit: it now
   621 takes ~= in premises into account (by performing a case split);
   622 
   623 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   624 are distributed over a sum of terms;
   625 
   626 * New tactic "trans_tac" and method "trans" instantiate
   627 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   628 "<=", "<" and "=").
   629 
   630 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main
   631 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   632 
   633 * 'typedef' command has new option "open" to suppress the set
   634 definition;
   635 
   636 * functions Min and Max on finite sets have been introduced (theory
   637 Finite_Set);
   638 
   639 * attribute [symmetric] now works for relations as well; it turns
   640 (x,y) : R^-1 into (y,x) : R, and vice versa;
   641 
   642 * induct over a !!-quantified statement (say !!x1..xn):
   643   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   644 
   645 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   646 %x. None. Warning: empty_def now refers to the previously hidden definition
   647 of the empty set.
   648 
   649 * Algebra: formalization of classical algebra.  Intended as base for
   650 any algebraic development in Isabelle.  Currently covers group theory
   651 (up to Sylow's theorem) and ring theory (Universal Property of
   652 Univariate Polynomials).  Contributions welcome;
   653 
   654 * GroupTheory: deleted, since its material has been moved to Algebra;
   655 
   656 * Complex: new directory of the complex numbers with numeric constants,
   657 nonstandard complex numbers, and some complex analysis, standard and
   658 nonstandard (Jacques Fleuriot);
   659 
   660 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   661 
   662 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques
   663 Fleuriot);
   664 
   665 * Real/HahnBanach: updated and adapted to locales;
   666 
   667 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   668 Gray and Kramer);
   669 
   670 * UNITY: added the Meier-Sanders theory of progress sets;
   671 
   672 * MicroJava: bytecode verifier and lightweight bytecode verifier
   673 as abstract algorithms, instantiated to the JVM;
   674 
   675 * Bali: Java source language formalization. Type system, operational
   676 semantics, axiomatic semantics. Supported language features:
   677 classes, interfaces, objects,virtual methods, static methods,
   678 static/instance fields, arrays, access modifiers, definite
   679 assignment, exceptions.
   680 
   681 
   682 *** ZF ***
   683 
   684 * ZF/Constructible: consistency proof for AC (Gdel's constructible
   685 universe, etc.);
   686 
   687 * Main ZF: virtually all theories converted to new-style format;
   688 
   689 
   690 *** ML ***
   691 
   692 * Pure: Tactic.prove provides sane interface for internal proofs;
   693 omits the infamous "standard" operation, so this is more appropriate
   694 than prove_goalw_cterm in many situations (e.g. in simprocs);
   695 
   696 * Pure: improved error reporting of simprocs;
   697 
   698 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   699 up simprocs;
   700 
   701 
   702 *** Document preparation ***
   703 
   704 * uses \par instead of \\ for line breaks in theory text. This may
   705 shift some page breaks in large documents. To get the old behaviour
   706 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   707 
   708 * minimized dependencies of isabelle.sty and isabellesym.sty on
   709 other packages
   710 
   711 * \<euro> now needs package babel/greek instead of marvosym (which
   712 broke \Rightarrow)
   713 
   714 * normal size for \<zero>...\<nine> (uses \mathbf instead of
   715 textcomp package)
   716 
   717 
   718 
   719 New in Isabelle2002 (March 2002)
   720 --------------------------------
   721 
   722 *** Document preparation ***
   723 
   724 * greatly simplified document preparation setup, including more
   725 graceful interpretation of isatool usedir -i/-d/-D options, and more
   726 instructive isatool mkdir; users should basically be able to get
   727 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   728 users may run a separate document processing stage manually like this:
   729 "isatool usedir -D output HOL Test && isatool document Test/output";
   730 
   731 * theory dependency graph may now be incorporated into documents;
   732 isatool usedir -g true will produce session_graph.eps/.pdf for use
   733 with \includegraphics of LaTeX;
   734 
   735 * proper spacing of consecutive markup elements, especially text
   736 blocks after section headings;
   737 
   738 * support bold style (for single symbols only), input syntax is like
   739 this: "\<^bold>\<alpha>" or "\<^bold>A";
   740 
   741 * \<bullet> is now output as bold \cdot by default, which looks much
   742 better in printed text;
   743 
   744 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   745 note that these symbols are currently unavailable in Proof General /
   746 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   747 
   748 * isatool latex no longer depends on changed TEXINPUTS, instead
   749 isatool document copies the Isabelle style files to the target
   750 location;
   751 
   752 
   753 *** Isar ***
   754 
   755 * Pure/Provers: improved proof by cases and induction;
   756   - 'case' command admits impromptu naming of parameters (such as
   757     "case (Suc n)");
   758   - 'induct' method divinates rule instantiation from the inductive
   759     claim; no longer requires excessive ?P bindings for proper
   760     instantiation of cases;
   761   - 'induct' method properly enumerates all possibilities of set/type
   762     rules; as a consequence facts may be also passed through *type*
   763     rules without further ado;
   764   - 'induct' method now derives symbolic cases from the *rulified*
   765     rule (before it used to rulify cases stemming from the internal
   766     atomized version); this means that the context of a non-atomic
   767     statement becomes is included in the hypothesis, avoiding the
   768     slightly cumbersome show "PROP ?case" form;
   769   - 'induct' may now use elim-style induction rules without chaining
   770     facts, using ``missing'' premises from the goal state; this allows
   771     rules stemming from inductive sets to be applied in unstructured
   772     scripts, while still benefitting from proper handling of non-atomic
   773     statements; NB: major inductive premises need to be put first, all
   774     the rest of the goal is passed through the induction;
   775   - 'induct' proper support for mutual induction involving non-atomic
   776     rule statements (uses the new concept of simultaneous goals, see
   777     below);
   778   - append all possible rule selections, but only use the first
   779     success (no backtracking);
   780   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   781   - undeclared rule case names default to numbers 1, 2, 3, ...;
   782   - added 'print_induct_rules' (covered by help item in recent Proof
   783     General versions);
   784   - moved induct/cases attributes to Pure, methods to Provers;
   785   - generic method setup instantiated for FOL and HOL;
   786 
   787 * Pure: support multiple simultaneous goal statements, for example
   788 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   789 meta-level mechanism, this acts as if several individual goals had
   790 been stated separately; in particular common proof methods need to be
   791 repeated in order to cover all claims; note that a single elimination
   792 step is *not* sufficient to establish the two conjunctions, so this
   793 fails:
   794 
   795   assume "A & B" then have A and B ..   (*".." fails*)
   796 
   797 better use "obtain" in situations as above; alternative refer to
   798 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   799 
   800 * Pure: proper integration with ``locales''; unlike the original
   801 version by Florian Kammller, Isar locales package high-level proof
   802 contexts rather than raw logical ones (e.g. we admit to include
   803 attributes everywhere); operations on locales include merge and
   804 rename; support for implicit arguments (``structures''); simultaneous
   805 type-inference over imports and text; see also HOL/ex/Locales.thy for
   806 some examples;
   807 
   808 * Pure: the following commands have been ``localized'', supporting a
   809 target locale specification "(in name)": 'lemma', 'theorem',
   810 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   811 stored both within the locale and at the theory level (exported and
   812 qualified by the locale name);
   813 
   814 * Pure: theory goals may now be specified in ``long'' form, with
   815 ad-hoc contexts consisting of arbitrary locale elements. for example
   816 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   817 definitions may be given, too); the result is a meta-level rule with
   818 the context elements being discharged in the obvious way;
   819 
   820 * Pure: new proof command 'using' allows to augment currently used
   821 facts after a goal statement ('using' is syntactically analogous to
   822 'apply', but acts on the goal's facts only); this allows chained facts
   823 to be separated into parts given before and after a claim, as in
   824 ``from a and b have C using d and e <proof>'';
   825 
   826 * Pure: renamed "antecedent" case to "rule_context";
   827 
   828 * Pure: new 'judgment' command records explicit information about the
   829 object-logic embedding (used by several tools internally); no longer
   830 use hard-wired "Trueprop";
   831 
   832 * Pure: added 'corollary' command;
   833 
   834 * Pure: fixed 'token_translation' command;
   835 
   836 * Pure: removed obsolete 'exported' attribute;
   837 
   838 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   839 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   840 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   841 
   842 * Pure: method 'atomize' presents local goal premises as object-level
   843 statements (atomic meta-level propositions); setup controlled via
   844 rewrite rules declarations of 'atomize' attribute; example
   845 application: 'induct' method with proper rule statements in improper
   846 proof *scripts*;
   847 
   848 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   849 now consider the syntactic context of assumptions, giving a better
   850 chance to get type-inference of the arguments right (this is
   851 especially important for locales);
   852 
   853 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   854 mode;
   855 
   856 * Pure/obtain: the formal conclusion "thesis", being marked as
   857 ``internal'', may no longer be reference directly in the text;
   858 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   859 situations;
   860 
   861 * Pure: generic 'sym' attribute which declares a rule both as pure
   862 'elim?' and for the 'symmetric' operation;
   863 
   864 * Pure: marginal comments ``--'' may now occur just anywhere in the
   865 text; the fixed correlation with particular command syntax has been
   866 discontinued;
   867 
   868 * Pure: new method 'rules' is particularly well-suited for proof
   869 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   870 but often produces more compact proof terms with less detours;
   871 
   872 * Pure/Provers/classical: simplified integration with pure rule
   873 attributes and methods; the classical "intro?/elim?/dest?"
   874 declarations coincide with the pure ones; the "rule" method no longer
   875 includes classically swapped intros; "intro" and "elim" methods no
   876 longer pick rules from the context; also got rid of ML declarations
   877 AddXIs/AddXEs/AddXDs; all of this has some potential for
   878 INCOMPATIBILITY;
   879 
   880 * Provers/classical: attribute 'swapped' produces classical inversions
   881 of introduction rules;
   882 
   883 * Provers/simplifier: 'simplified' attribute may refer to explicit
   884 rules instead of full simplifier context; 'iff' attribute handles
   885 conditional rules;
   886 
   887 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   888 
   889 * HOL: 'recdef' now fails on unfinished automated proofs, use
   890 "(permissive)" option to recover old behavior;
   891 
   892 * HOL: 'inductive' no longer features separate (collective) attributes
   893 for 'intros' (was found too confusing);
   894 
   895 * HOL: properly declared induction rules less_induct and
   896 wf_induct_rule;
   897 
   898 
   899 *** HOL ***
   900 
   901 * HOL: moved over to sane numeral syntax; the new policy is as
   902 follows:
   903 
   904   - 0 and 1 are polymorphic constants, which are defined on any
   905   numeric type (nat, int, real etc.);
   906 
   907   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   908   binary representation internally;
   909 
   910   - type nat has special constructor Suc, and generally prefers Suc 0
   911   over 1::nat and Suc (Suc 0) over 2::nat;
   912 
   913 This change may cause significant problems of INCOMPATIBILITY; here
   914 are some hints on converting existing sources:
   915 
   916   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   917   entities, so expressions involving "-" (unary or binary minus) need
   918   to be spaced properly;
   919 
   920   - existing occurrences of "1" may need to be constraint "1::nat" or
   921   even replaced by Suc 0; similar for old "2";
   922 
   923   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   924 
   925   - remove all special provisions on numerals in proofs;
   926 
   927 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   928 representation (depends on bin_arith_simps in the default context);
   929 
   930 * HOL: symbolic syntax for x^2 (numeral 2);
   931 
   932 * HOL: the class of all HOL types is now called "type" rather than
   933 "term"; INCOMPATIBILITY, need to adapt references to this type class
   934 in axclass/classes, instance/arities, and (usually rare) occurrences
   935 in typings (of consts etc.); internally the class is called
   936 "HOL.type", ML programs should refer to HOLogic.typeS;
   937 
   938 * HOL/record package improvements:
   939   - new derived operations "fields" to build a partial record section,
   940     "extend" to promote a fixed record to a record scheme, and
   941     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   942     declared as simp by default;
   943   - shared operations ("more", "fields", etc.) now need to be always
   944     qualified) --- potential INCOMPATIBILITY;
   945   - removed "make_scheme" operations (use "make" with "extend") --
   946     INCOMPATIBILITY;
   947   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   948   - provides cases/induct rules for use with corresponding Isar
   949     methods (for concrete records, record schemes, concrete more
   950     parts, and schematic more parts -- in that order);
   951   - internal definitions directly based on a light-weight abstract
   952     theory of product types over typedef rather than datatype;
   953 
   954 * HOL: generic code generator for generating executable ML code from
   955 specifications; specific support for HOL constructs such as inductive
   956 datatypes and sets, as well as recursive functions; can be invoked
   957 via 'generate_code' theory section;
   958 
   959 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   960 
   961 * HOL: consolidated and renamed several theories.  In particular:
   962         Ord.thy has been absorbed into HOL.thy
   963         String.thy has been absorbed into List.thy
   964 
   965 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   966 (beware of argument permutation!);
   967 
   968 * HOL: linorder_less_split superseded by linorder_cases;
   969 
   970 * HOL/List: "nodups" renamed to "distinct";
   971 
   972 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   973 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   974   - Ex_def has changed, now need to use some_eq_ex
   975 
   976 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   977 in this (rare) case use:
   978 
   979   delSWrapper "split_all_tac"
   980   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   981 
   982 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   983 MAY FAIL;
   984 
   985 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   986 Isabelle's type classes, ^ on functions and relations has too general
   987 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   988 necessary to attach explicit type constraints;
   989 
   990 * HOL/Relation: the prefix name of the infix "O" has been changed from
   991 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   992 renamed accordingly (eg "compI" -> "rel_compI").
   993 
   994 * HOL: syntax translations now work properly with numerals and records
   995 expressions;
   996 
   997 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   998 of "lam" -- INCOMPATIBILITY;
   999 
  1000 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
  1001 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
  1002 renamed "Product_Type.unit";
  1003 
  1004 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
  1005 
  1006 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
  1007 the "cases" method);
  1008 
  1009 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
  1010 Florian Kammller);
  1011 
  1012 * HOL/IMP: updated and converted to new-style theory format; several
  1013 parts turned into readable document, with proper Isar proof texts and
  1014 some explanations (by Gerwin Klein);
  1015 
  1016 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
  1017 
  1018 * HOL-Hyperreal is now a logic image;
  1019 
  1020 
  1021 *** HOLCF ***
  1022 
  1023 * Isar: consts/constdefs supports mixfix syntax for continuous
  1024 operations;
  1025 
  1026 * Isar: domain package adapted to new-style theory format, e.g. see
  1027 HOLCF/ex/Dnat.thy;
  1028 
  1029 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
  1030 potential INCOMPATIBILITY; now use plain induct_tac instead of former
  1031 lift.induct_tac, always use UU instead of Undef;
  1032 
  1033 * HOLCF/IMP: updated and converted to new-style theory;
  1034 
  1035 
  1036 *** ZF ***
  1037 
  1038 * Isar: proper integration of logic-specific tools and packages,
  1039 including theory commands '(co)inductive', '(co)datatype',
  1040 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
  1041 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
  1042 
  1043 * theory Main no longer includes AC; for the Axiom of Choice, base
  1044 your theory on Main_ZFC;
  1045 
  1046 * the integer library now covers quotients and remainders, with many
  1047 laws relating division to addition, multiplication, etc.;
  1048 
  1049 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
  1050 typeless version of the formalism;
  1051 
  1052 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
  1053 format;
  1054 
  1055 * ZF/Induct: new directory for examples of inductive definitions,
  1056 including theory Multiset for multiset orderings; converted to
  1057 new-style theory format;
  1058 
  1059 * ZF: many new theorems about lists, ordinals, etc.;
  1060 
  1061 
  1062 *** General ***
  1063 
  1064 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
  1065 variable proof controls level of detail: 0 = no proofs (only oracle
  1066 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
  1067 also ref manual for further ML interfaces;
  1068 
  1069 * Pure/axclass: removed obsolete ML interface
  1070 goal_subclass/goal_arity;
  1071 
  1072 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
  1073 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
  1074 separate tokens, so expressions involving minus need to be spaced
  1075 properly;
  1076 
  1077 * Pure/syntax: support non-oriented infixes, using keyword "infix"
  1078 rather than "infixl" or "infixr";
  1079 
  1080 * Pure/syntax: concrete syntax for dummy type variables admits genuine
  1081 sort constraint specifications in type inference; e.g. "x::_::foo"
  1082 ensures that the type of "x" is of sort "foo" (but not necessarily a
  1083 type variable);
  1084 
  1085 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
  1086 control output of nested => (types); the default behavior is
  1087 "type_brackets";
  1088 
  1089 * Pure/syntax: builtin parse translation for "_constify" turns valued
  1090 tokens into AST constants;
  1091 
  1092 * Pure/syntax: prefer later declarations of translations and print
  1093 translation functions; potential INCOMPATIBILITY: need to reverse
  1094 multiple declarations for same syntax element constant;
  1095 
  1096 * Pure/show_hyps reset by default (in accordance to existing Isar
  1097 practice);
  1098 
  1099 * Provers/classical: renamed addaltern to addafter, addSaltern to
  1100 addSafter;
  1101 
  1102 * Provers/clasimp: ``iff'' declarations now handle conditional rules
  1103 as well;
  1104 
  1105 * system: tested support for MacOS X; should be able to get Isabelle +
  1106 Proof General to work in a plain Terminal after installing Poly/ML
  1107 (e.g. from the Isabelle distribution area) and GNU bash alone
  1108 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
  1109 support requires further installations, e.g. from
  1110 http://fink.sourceforge.net/);
  1111 
  1112 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
  1113 
  1114 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
  1115 of 40 MB), cf. ML_OPTIONS;
  1116 
  1117 * system: Proof General keywords specification is now part of the
  1118 Isabelle distribution (see etc/isar-keywords.el);
  1119 
  1120 * system: support for persistent Proof General sessions (refrain from
  1121 outdating all loaded theories on startup); user may create writable
  1122 logic images like this: ``isabelle -q HOL Test'';
  1123 
  1124 * system: smart selection of Isabelle process versus Isabelle
  1125 interface, accommodates case-insensitive file systems (e.g. HFS+); may
  1126 run both "isabelle" and "Isabelle" even if file names are badly
  1127 damaged (executable inspects the case of the first letter of its own
  1128 name); added separate "isabelle-process" and "isabelle-interface";
  1129 
  1130 * system: refrain from any attempt at filtering input streams; no
  1131 longer support ``8bit'' encoding of old isabelle font, instead proper
  1132 iso-latin characters may now be used; the related isatools
  1133 "symbolinput" and "nonascii" have disappeared as well;
  1134 
  1135 * system: removed old "xterm" interface (the print modes "xterm" and
  1136 "xterm_color" are still available for direct use in a suitable
  1137 terminal);
  1138 
  1139 
  1140 
  1141 New in Isabelle99-2 (February 2001)
  1142 -----------------------------------
  1143 
  1144 *** Overview of INCOMPATIBILITIES ***
  1145 
  1146 * HOL: please note that theories in the Library and elsewhere often use the
  1147 new-style (Isar) format; to refer to their theorems in an ML script you must
  1148 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
  1149 
  1150 * HOL: inductive package no longer splits induction rule aggressively,
  1151 but only as far as specified by the introductions given; the old
  1152 format may be recovered via ML function complete_split_rule or attribute
  1153 'split_rule (complete)';
  1154 
  1155 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
  1156 gfp_Tarski to gfp_unfold;
  1157 
  1158 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
  1159 
  1160 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
  1161 relation); infix "^^" has been renamed "``"; infix "``" has been
  1162 renamed "`"; "univalent" has been renamed "single_valued";
  1163 
  1164 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
  1165 operation;
  1166 
  1167 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
  1168 
  1169 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
  1170 
  1171 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
  1172 consequence, it is no longer monotonic wrt. the local goal context
  1173 (which is now passed through the inductive cases);
  1174 
  1175 * Document preparation: renamed standard symbols \<ll> to \<lless> and
  1176 \<gg> to \<ggreater>;
  1177 
  1178 
  1179 *** Document preparation ***
  1180 
  1181 * \isabellestyle{NAME} selects version of Isabelle output (currently
  1182 available: are "it" for near math-mode best-style output, "sl" for
  1183 slanted text style, and "tt" for plain type-writer; if no
  1184 \isabellestyle command is given, output is according to slanted
  1185 type-writer);
  1186 
  1187 * support sub/super scripts (for single symbols only), input syntax is
  1188 like this: "A\<^sup>*" or "A\<^sup>\<star>";
  1189 
  1190 * some more standard symbols; see Appendix A of the system manual for
  1191 the complete list of symbols defined in isabellesym.sty;
  1192 
  1193 * improved isabelle style files; more abstract symbol implementation
  1194 (should now use \isamath{...} and \isatext{...} in custom symbol
  1195 definitions);
  1196 
  1197 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
  1198 state; Note that presentation of goal states does not conform to
  1199 actual human-readable proof documents.  Please do not include goal
  1200 states into document output unless you really know what you are doing!
  1201 
  1202 * proper indentation of antiquoted output with proportional LaTeX
  1203 fonts;
  1204 
  1205 * no_document ML operator temporarily disables LaTeX document
  1206 generation;
  1207 
  1208 * isatool unsymbolize tunes sources for plain ASCII communication;
  1209 
  1210 
  1211 *** Isar ***
  1212 
  1213 * Pure: Isar now suffers initial goal statements to contain unbound
  1214 schematic variables (this does not conform to actual readable proof
  1215 documents, due to unpredictable outcome and non-compositional proof
  1216 checking); users who know what they are doing may use schematic goals
  1217 for Prolog-style synthesis of proven results;
  1218 
  1219 * Pure: assumption method (an implicit finishing) now handles actual
  1220 rules as well;
  1221 
  1222 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
  1223 initial goal, declare "that" only as Pure intro (only for single
  1224 steps); the "that" rule assumption may now be involved in implicit
  1225 finishing, thus ".." becomes a feasible for trivial obtains;
  1226 
  1227 * Pure: default proof step now includes 'intro_classes'; thus trivial
  1228 instance proofs may be performed by "..";
  1229 
  1230 * Pure: ?thesis / ?this / "..." now work for pure meta-level
  1231 statements as well;
  1232 
  1233 * Pure: more robust selection of calculational rules;
  1234 
  1235 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
  1236 rule (as well as the assumption rule);
  1237 
  1238 * Pure: 'thm_deps' command visualizes dependencies of theorems and
  1239 lemmas, using the graph browser tool;
  1240 
  1241 * Pure: predict failure of "show" in interactive mode;
  1242 
  1243 * Pure: 'thms_containing' now takes actual terms as arguments;
  1244 
  1245 * HOL: improved method 'induct' --- now handles non-atomic goals
  1246 (potential INCOMPATIBILITY); tuned error handling;
  1247 
  1248 * HOL: cases and induct rules now provide explicit hints about the
  1249 number of facts to be consumed (0 for "type" and 1 for "set" rules);
  1250 any remaining facts are inserted into the goal verbatim;
  1251 
  1252 * HOL: local contexts (aka cases) may now contain term bindings as
  1253 well; the 'cases' and 'induct' methods new provide a ?case binding for
  1254 the result to be shown in each case;
  1255 
  1256 * HOL: added 'recdef_tc' command;
  1257 
  1258 * isatool convert assists in eliminating legacy ML scripts;
  1259 
  1260 
  1261 *** HOL ***
  1262 
  1263 * HOL/Library: a collection of generic theories to be used together
  1264 with main HOL; the theory loader path already includes this directory
  1265 by default; the following existing theories have been moved here:
  1266 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
  1267 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
  1268 
  1269 * HOL/Unix: "Some aspects of Unix file-system security", a typical
  1270 modelling and verification task performed in Isabelle/HOL +
  1271 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
  1272 
  1273 * HOL/Algebra: special summation operator SUM no longer exists, it has
  1274 been replaced by setsum; infix 'assoc' now has priority 50 (like
  1275 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
  1276 'domain', this makes the theory consistent with mathematical
  1277 literature;
  1278 
  1279 * HOL basics: added overloaded operations "inverse" and "divide"
  1280 (infix "/"), syntax for generic "abs" operation, generic summation
  1281 operator \<Sum>;
  1282 
  1283 * HOL/typedef: simplified package, provide more useful rules (see also
  1284 HOL/subset.thy);
  1285 
  1286 * HOL/datatype: induction rule for arbitrarily branching datatypes is
  1287 now expressed as a proper nested rule (old-style tactic scripts may
  1288 require atomize_strip_tac to cope with non-atomic premises);
  1289 
  1290 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
  1291 to "split_conv" (old name still available for compatibility);
  1292 
  1293 * HOL: improved concrete syntax for strings (e.g. allows translation
  1294 rules with string literals);
  1295 
  1296 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
  1297  and Fleuriot's mechanization of analysis, including the transcendental
  1298  functions for the reals;
  1299 
  1300 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
  1301 
  1302 
  1303 *** CTT ***
  1304 
  1305 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
  1306 "lam" is displayed as TWO lambda-symbols
  1307 
  1308 * CTT: theory Main now available, containing everything (that is, Bool
  1309 and Arith);
  1310 
  1311 
  1312 *** General ***
  1313 
  1314 * Pure: the Simplifier has been implemented properly as a derived rule
  1315 outside of the actual kernel (at last!); the overall performance
  1316 penalty in practical applications is about 50%, while reliability of
  1317 the Isabelle inference kernel has been greatly improved;
  1318 
  1319 * print modes "brackets" and "no_brackets" control output of nested =>
  1320 (types) and ==> (props); the default behaviour is "brackets";
  1321 
  1322 * Provers: fast_tac (and friends) now handle actual object-logic rules
  1323 as assumptions as well;
  1324 
  1325 * system: support Poly/ML 4.0;
  1326 
  1327 * system: isatool install handles KDE version 1 or 2;
  1328 
  1329 
  1330 
  1331 New in Isabelle99-1 (October 2000)
  1332 ----------------------------------
  1333 
  1334 *** Overview of INCOMPATIBILITIES ***
  1335 
  1336 * HOL: simplification of natural numbers is much changed; to partly
  1337 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
  1338 issue the following ML commands:
  1339 
  1340   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
  1341   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
  1342 
  1343 * HOL: simplification no longer dives into case-expressions; this is
  1344 controlled by "t.weak_case_cong" for each datatype t;
  1345 
  1346 * HOL: nat_less_induct renamed to less_induct;
  1347 
  1348 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
  1349 fixsome to patch .thy and .ML sources automatically;
  1350 
  1351   select_equality  -> some_equality
  1352   select_eq_Ex     -> some_eq_ex
  1353   selectI2EX       -> someI2_ex
  1354   selectI2         -> someI2
  1355   selectI          -> someI
  1356   select1_equality -> some1_equality
  1357   Eps_sym_eq       -> some_sym_eq_trivial
  1358   Eps_eq           -> some_eq_trivial
  1359 
  1360 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
  1361 
  1362 * HOL: removed obsolete theorem binding expand_if (refer to split_if
  1363 instead);
  1364 
  1365 * HOL: the recursion equations generated by 'recdef' are now called
  1366 f.simps instead of f.rules;
  1367 
  1368 * HOL: qed_spec_mp now also handles bounded ALL as well;
  1369 
  1370 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  1371 sometimes be needed;
  1372 
  1373 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  1374 
  1375 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  1376 
  1377 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  1378 product is now "<*>" instead of "Times"; the lexicographic product is
  1379 now "<*lex*>" instead of "**";
  1380 
  1381 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  1382 of main HOL, but was unused); better use HOL's datatype package;
  1383 
  1384 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  1385 the old syntax may be recovered as follows:
  1386 
  1387   syntax (symbols)
  1388     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  1389       (infixl "\\<oplus>" 100)
  1390 
  1391 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1392 
  1393 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1394 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1395 internally;
  1396 
  1397 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1398 changed from A/r to A//r;
  1399 
  1400 * ZF: new treatment of arithmetic (nat & int) may break some old
  1401 proofs;
  1402 
  1403 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1404 rulify -> rule_format, elimify -> elim_format, ...);
  1405 
  1406 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1407 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1408 should have to change intro!! to intro? only); replaced "delrule" by
  1409 "rule del";
  1410 
  1411 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1412 
  1413 * Provers: strengthened force_tac by using new first_best_tac;
  1414 
  1415 * LaTeX document preparation: several changes of isabelle.sty (see
  1416 lib/texinputs);
  1417 
  1418 
  1419 *** Document preparation ***
  1420 
  1421 * formal comments (text blocks etc.) in new-style theories may now
  1422 contain antiquotations of thm/prop/term/typ/text to be presented
  1423 according to latex print mode; concrete syntax is like this:
  1424 @{term[show_types] "f(x) = a + x"};
  1425 
  1426 * isatool mkdir provides easy setup of Isabelle session directories,
  1427 including proper document sources;
  1428 
  1429 * generated LaTeX sources are now deleted after successful run
  1430 (isatool document -c); may retain a copy somewhere else via -D option
  1431 of isatool usedir;
  1432 
  1433 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1434 style files, achieving self-contained LaTeX sources and simplifying
  1435 LaTeX debugging;
  1436 
  1437 * old-style theories now produce (crude) LaTeX output as well;
  1438 
  1439 * browser info session directories are now self-contained (may be put
  1440 on WWW server seperately); improved graphs of nested sessions; removed
  1441 graph for 'all sessions';
  1442 
  1443 * several improvements in isabelle style files; \isabellestyle{it}
  1444 produces fake math mode output; \isamarkupheader is now \section by
  1445 default; see lib/texinputs/isabelle.sty etc.;
  1446 
  1447 
  1448 *** Isar ***
  1449 
  1450 * Isar/Pure: local results and corresponding term bindings are now
  1451 subject to Hindley-Milner polymorphism (similar to ML); this
  1452 accommodates incremental type-inference very nicely;
  1453 
  1454 * Isar/Pure: new derived language element 'obtain' supports
  1455 generalized existence reasoning;
  1456 
  1457 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1458 support accumulation of results, without applying any rules yet;
  1459 useful to collect intermediate results without explicit name
  1460 references, and for use with transitivity rules with more than 2
  1461 premises;
  1462 
  1463 * Isar/Pure: scalable support for case-analysis type proofs: new
  1464 'case' language element refers to local contexts symbolically, as
  1465 produced by certain proof methods; internally, case names are attached
  1466 to theorems as "tags";
  1467 
  1468 * Isar/Pure: theory command 'hide' removes declarations from
  1469 class/type/const name spaces;
  1470 
  1471 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1472 indicate potential overloading;
  1473 
  1474 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1475 
  1476 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1477 "{a,b,c}" instead of {a,b,c};
  1478 
  1479 * Isar/Pure now provides its own version of intro/elim/dest
  1480 attributes; useful for building new logics, but beware of confusion
  1481 with the version in Provers/classical;
  1482 
  1483 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1484 case name 'antecedent';
  1485 
  1486 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1487 to the current context is now done automatically);
  1488 
  1489 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1490 for definining proof methods in ML;
  1491 
  1492 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1493 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1494 most cases, one should have to change intro!! to intro? only);
  1495 replaced "delrule" by "rule del";
  1496 
  1497 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1498 'symmetric' attribute (the latter supercedes [RS sym]);
  1499 
  1500 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1501 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1502 well (including splits);
  1503 
  1504 * Isar/Provers: Simplifier and Classical methods now support all kind
  1505 of modifiers used in the past, including 'cong', 'iff', etc.
  1506 
  1507 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1508 of Simplifier and Classical reasoner);
  1509 
  1510 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1511 now support named cases; major packages (inductive, datatype, primrec,
  1512 recdef) support case names and properly name parameters;
  1513 
  1514 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1515 monotonicity conditions are extracted to be proven at end of
  1516 calculations;
  1517 
  1518 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1519 method anyway;
  1520 
  1521 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1522 split_if split_if_asm; datatype package provides theorems foo.splits =
  1523 foo.split foo.split_asm for each datatype;
  1524 
  1525 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1526 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1527 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1528 use "(cases (simplified))" method in proper proof texts);
  1529 
  1530 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1531 
  1532 * Isar: names of theorems etc. may be natural numbers as well;
  1533 
  1534 * Isar: 'pr' command: optional arguments for goals_limit and
  1535 ProofContext.prems_limit; no longer prints theory contexts, but only
  1536 proof states;
  1537 
  1538 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1539 additional print modes to be specified; e.g. "pr(latex)" will print
  1540 proof state according to the Isabelle LaTeX style;
  1541 
  1542 * Isar: improved support for emulating tactic scripts, including proof
  1543 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1544 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1545 (for HOL datatypes);
  1546 
  1547 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1548 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1549 'proof method scripts' have to be in depth-first order;
  1550 
  1551 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1552 
  1553 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1554 should instead use individual commands for printing items
  1555 (print_commands, print_methods etc.);
  1556 
  1557 * Isar: added 'nothing' --- the empty list of theorems;
  1558 
  1559 
  1560 *** HOL ***
  1561 
  1562 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1563 corresponding virtual machine and a specification of its bytecode
  1564 verifier and a lightweight bytecode verifier, including proofs of
  1565 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1566 Cornelia Pusch (see also the homepage of project Bali at
  1567 http://isabelle.in.tum.de/Bali/);
  1568 
  1569 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1570 Clemens Ballarin;
  1571 
  1572 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1573 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1574 Rasmussen;
  1575 
  1576 * HOL/Lattice: fundamental concepts of lattice theory and order
  1577 structures, including duals, properties of bounds versus algebraic
  1578 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1579 Theorem for complete lattices etc.; may also serve as a demonstration
  1580 for abstract algebraic reasoning using axiomatic type classes, and
  1581 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1582 
  1583 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1584 von Oheimb;
  1585 
  1586 * HOL/IMPP: extension of IMP with local variables and mutually
  1587 recursive procedures, by David von Oheimb;
  1588 
  1589 * HOL/Lambda: converted into new-style theory and document;
  1590 
  1591 * HOL/ex/Multiquote: example of multiple nested quotations and
  1592 anti-quotations -- basically a generalized version of de-Bruijn
  1593 representation; very useful in avoiding lifting of operations;
  1594 
  1595 * HOL/record: added general record equality rule to simpset; fixed
  1596 select-update simplification procedure to handle extended records as
  1597 well; admit "r" as field name;
  1598 
  1599 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1600 other numeric types and also as the identity of groups, rings, etc.;
  1601 
  1602 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1603 Types nat and int belong to this axclass;
  1604 
  1605 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1606    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1607    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1608   two terms #m*u and #n*u are replaced by #(m+n)*u
  1609     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1610   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1611     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1612 
  1613 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1614 powerful prover for predicate logic but knows nothing of clasets; see
  1615 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1616 
  1617 * HOL: new version of "case_tac" subsumes both boolean case split and
  1618 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1619 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1620 
  1621 * HOL: simplification no longer dives into case-expressions: only the
  1622 selector expression is simplified, but not the remaining arms; to
  1623 enable full simplification of case-expressions for datatype t, you may
  1624 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1625 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1626 
  1627 * HOL/recdef: the recursion equations generated by 'recdef' for
  1628 function 'f' are now called f.simps instead of f.rules; if all
  1629 termination conditions are proved automatically, these simplification
  1630 rules are added to the simpset, as in primrec; rules may be named
  1631 individually as well, resulting in a separate list of theorems for
  1632 each equation;
  1633 
  1634 * HOL/While is a new theory that provides a while-combinator. It
  1635 permits the definition of tail-recursive functions without the
  1636 provision of a termination measure. The latter is necessary once the
  1637 invariant proof rule for while is applied.
  1638 
  1639 * HOL: new (overloaded) notation for the set of elements below/above
  1640 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1641 
  1642 * HOL: theorems impI, allI, ballI bound as "strip";
  1643 
  1644 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1645 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1646 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1647 
  1648 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1649 
  1650 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1651 main HOL, but was unused);
  1652 
  1653 * HOL: fewer consts declared as global (e.g. have to refer to
  1654 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1655 
  1656 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1657 in case of overlap with user translations (e.g. judgements over
  1658 tuples); (note that the underlying logical represenation is still
  1659 bogus);
  1660 
  1661 
  1662 *** ZF ***
  1663 
  1664 * ZF: simplification automatically cancels common terms in arithmetic
  1665 expressions over nat and int;
  1666 
  1667 * ZF: new treatment of nat to minimize type-checking: all operators
  1668 coerce their operands to a natural number using the function natify,
  1669 making the algebraic laws unconditional;
  1670 
  1671 * ZF: as above, for int: operators coerce their operands to an integer
  1672 using the function intify;
  1673 
  1674 * ZF: the integer library now contains many of the usual laws for the
  1675 orderings, including $<=, and monotonicity laws for $+ and $*;
  1676 
  1677 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1678 simplification;
  1679 
  1680 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1681 to the simplifier and classical reasoner simultaneously;
  1682 
  1683 
  1684 *** General ***
  1685 
  1686 * Provers: blast_tac now handles actual object-logic rules as
  1687 assumptions; note that auto_tac uses blast_tac internally as well;
  1688 
  1689 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1690 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1691 
  1692 * Provers: delrules now handles destruct rules as well (no longer need
  1693 explicit make_elim);
  1694 
  1695 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1696   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1697 use instead the strong form,
  1698   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1699 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1700 from destruct-rules;
  1701 
  1702 * Provers: Simplifier.easy_setup provides a fast path to basic
  1703 Simplifier setup for new object-logics;
  1704 
  1705 * Pure: AST translation rules no longer require constant head on LHS;
  1706 
  1707 * Pure: improved name spaces: ambiguous output is qualified; support
  1708 for hiding of names;
  1709 
  1710 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1711 XSYMBOL_HOME; no longer need to do manual configuration in most
  1712 situations;
  1713 
  1714 * system: compression of ML heaps images may now be controlled via -c
  1715 option of isabelle and isatool usedir (currently only observed by
  1716 Poly/ML);
  1717 
  1718 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1719 useful for remote X11);
  1720 
  1721 * system: provide TAGS file for Isabelle sources;
  1722 
  1723 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1724 order;
  1725 
  1726 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1727 timing flag supersedes proof_timing and Toplevel.trace;
  1728 
  1729 * ML: new combinators |>> and |>>> for incremental transformations
  1730 with secondary results (e.g. certain theory extensions):
  1731 
  1732 * ML: PureThy.add_defs gets additional argument to indicate potential
  1733 overloading (usually false);
  1734 
  1735 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1736 results;
  1737 
  1738 
  1739 
  1740 New in Isabelle99 (October 1999)
  1741 --------------------------------
  1742 
  1743 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1744 
  1745 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1746 are no longer simplified.  (This allows the simplifier to unfold recursive
  1747 functional programs.)  To restore the old behaviour, declare
  1748 
  1749     Delcongs [if_weak_cong];
  1750 
  1751 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1752 complement;
  1753 
  1754 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1755 
  1756 * HOL/datatype: mutual_induct_tac no longer exists --
  1757   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1758 
  1759 * HOL/typedef: fixed type inference for representing set; type
  1760 arguments now have to occur explicitly on the rhs as type constraints;
  1761 
  1762 * ZF: The con_defs part of an inductive definition may no longer refer
  1763 to constants declared in the same theory;
  1764 
  1765 * HOL, ZF: the function mk_cases, generated by the inductive
  1766 definition package, has lost an argument.  To simplify its result, it
  1767 uses the default simpset instead of a supplied list of theorems.
  1768 
  1769 * HOL/List: the constructors of type list are now Nil and Cons;
  1770 
  1771 * Simplifier: the type of the infix ML functions
  1772         setSSolver addSSolver setSolver addSolver
  1773 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1774 for packaging solvers. A solver is created via
  1775         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1776 where the string argument is only a comment.
  1777 
  1778 
  1779 *** Proof tools ***
  1780 
  1781 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1782 decision procedure for linear arithmetic. Currently it is used for
  1783 types `nat', `int', and `real' in HOL (see below); it can, should and
  1784 will be instantiated for other types and logics as well.
  1785 
  1786 * The simplifier now accepts rewrite rules with flexible heads, eg
  1787      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1788   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1789   matching.
  1790 
  1791 
  1792 *** General ***
  1793 
  1794 * New Isabelle/Isar subsystem provides an alternative to traditional
  1795 tactical theorem proving; together with the ProofGeneral/isar user
  1796 interface it offers an interactive environment for developing human
  1797 readable proof documents (Isar == Intelligible semi-automated
  1798 reasoning); for further information see isatool doc isar-ref,
  1799 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1800 
  1801 * improved and simplified presentation of theories: better HTML markup
  1802 (including colors), graph views in several sizes; isatool usedir now
  1803 provides a proper interface for user theories (via -P option); actual
  1804 document preparation based on (PDF)LaTeX is available as well (for
  1805 new-style theories only); see isatool doc system for more information;
  1806 
  1807 * native support for Proof General, both for classic Isabelle and
  1808 Isabelle/Isar;
  1809 
  1810 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1811 using the graph browser tool;
  1812 
  1813 * Isabelle manuals now also available as PDF;
  1814 
  1815 * theory loader rewritten from scratch (may not be fully
  1816 bug-compatible); old loadpath variable has been replaced by show_path,
  1817 add_path, del_path, reset_path functions; new operations such as
  1818 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1819 isatool doc ref);
  1820 
  1821 * improved isatool install: option -k creates KDE application icon,
  1822 option -p DIR installs standalone binaries;
  1823 
  1824 * added ML_PLATFORM setting (useful for cross-platform installations);
  1825 more robust handling of platform specific ML images for SML/NJ;
  1826 
  1827 * the settings environment is now statically scoped, i.e. it is never
  1828 created again in sub-processes invoked from isabelle, isatool, or
  1829 Isabelle;
  1830 
  1831 * path element specification '~~' refers to '$ISABELLE_HOME';
  1832 
  1833 * in locales, the "assumes" and "defines" parts may be omitted if
  1834 empty;
  1835 
  1836 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1837 long arrows);
  1838 
  1839 * new print_mode "HTML";
  1840 
  1841 * new flag show_tags controls display of tags of theorems (which are
  1842 basically just comments that may be attached by some tools);
  1843 
  1844 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1845 mode and goal output format:
  1846 
  1847 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1848 244c244
  1849 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1850 ---
  1851 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1852 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1853 181c181
  1854 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1855 ---
  1856 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1857 
  1858 * function bind_thms stores lists of theorems (cf. bind_thm);
  1859 
  1860 * new shorthand tactics ftac, eatac, datac, fatac;
  1861 
  1862 * qed (and friends) now accept "" as result name; in that case the
  1863 theorem is not stored, but proper checks and presentation of the
  1864 result still apply;
  1865 
  1866 * theorem database now also indexes constants "Trueprop", "all",
  1867 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1868 
  1869 
  1870 *** HOL ***
  1871 
  1872 ** HOL arithmetic **
  1873 
  1874 * There are now decision procedures for linear arithmetic over nat and
  1875 int:
  1876 
  1877 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1878 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1879 are treated as atomic; subformulae not involving type `nat' or `int'
  1880 are ignored; quantified subformulae are ignored unless they are
  1881 positive universal or negative existential. The tactic has to be
  1882 invoked by hand and can be a little bit slow. In particular, the
  1883 running time is exponential in the number of occurrences of `min' and
  1884 `max', and `-' on `nat'.
  1885 
  1886 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1887 (negated) (in)equalities among the premises and the conclusion into
  1888 account (i.e. no compound formulae) and does not know about `min' and
  1889 `max', and `-' on `nat'. It is fast and is used automatically by the
  1890 simplifier.
  1891 
  1892 NB: At the moment, these decision procedures do not cope with mixed
  1893 nat/int formulae where the two parts interact, such as `m < n ==>
  1894 int(m) < int(n)'.
  1895 
  1896 * HOL/Numeral provides a generic theory of numerals (encoded
  1897 efficiently as bit strings); setup for types nat/int/real is in place;
  1898 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1899 int, existing theories and proof scripts may require a few additional
  1900 type constraints;
  1901 
  1902 * integer division and remainder can now be performed on constant
  1903 arguments;
  1904 
  1905 * many properties of integer multiplication, division and remainder
  1906 are now available;
  1907 
  1908 * An interface to the Stanford Validity Checker (SVC) is available through the
  1909 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1910 are proved automatically.  SVC must be installed separately, and its results
  1911 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1912 invocation of the underlying oracle).  For SVC see
  1913   http://verify.stanford.edu/SVC
  1914 
  1915 * IsaMakefile: the HOL-Real target now builds an actual image;
  1916 
  1917 
  1918 ** HOL misc **
  1919 
  1920 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1921 (in Isabelle/Isar) -- by Gertrud Bauer;
  1922 
  1923 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1924 analysis for assembly languages with subtypes;
  1925 
  1926 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1927 -- avoids syntactic ambiguities and treats state, transition, and
  1928 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1929 changed syntax and (many) tactics;
  1930 
  1931 * HOL/inductive: Now also handles more general introduction rules such
  1932   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1933   theorems are now maintained within the theory (maintained via the
  1934   "mono" attribute);
  1935 
  1936 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1937   (using function types) such as
  1938 
  1939   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1940 
  1941 * HOL/record: record_simproc (part of the default simpset) takes care
  1942 of selectors applied to updated records; record_split_tac is no longer
  1943 part of the default claset; update_defs may now be removed from the
  1944 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1945 
  1946   claset_ref () := claset() addSWrapper record_split_wrapper;
  1947   Delsimprocs [record_simproc]
  1948 
  1949 * HOL/typedef: fixed type inference for representing set; type
  1950 arguments now have to occur explicitly on the rhs as type constraints;
  1951 
  1952 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1953 names rather than an ML expression;
  1954 
  1955 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1956 supplied later.  Program schemes can be defined, such as
  1957     "While B C s = (if B s then While B C (C s) else s)"
  1958 where the well-founded relation can be chosen after B and C have been given.
  1959 
  1960 * HOL/List: the constructors of type list are now Nil and Cons;
  1961 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1962 course, ML tools referring to List.list.op # etc. have to be adapted;
  1963 
  1964 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1965 disabled by default; run isabelle with option -m HOL to get back to
  1966 the original Gordon/HOL-style output;
  1967 
  1968 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1969 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1970 
  1971 * HOL basic syntax simplified (more orthogonal): all variants of
  1972 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1973 Eps operator is provided as well: "SOME x. P[x]";
  1974 
  1975 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1976 
  1977 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1978 thus available for user theories;
  1979 
  1980 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1981 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1982 time;
  1983 
  1984 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1985 several times and then mp;
  1986 
  1987 
  1988 *** LK ***
  1989 
  1990 * the notation <<...>> is now available as a notation for sequences of
  1991 formulas;
  1992 
  1993 * the simplifier is now installed
  1994 
  1995 * the axiom system has been generalized (thanks to Soren Heilmann)
  1996 
  1997 * the classical reasoner now has a default rule database
  1998 
  1999 
  2000 *** ZF ***
  2001 
  2002 * new primrec section allows primitive recursive functions to be given
  2003 directly (as in HOL) over datatypes and the natural numbers;
  2004 
  2005 * new tactics induct_tac and exhaust_tac for induction (or case
  2006 analysis) over datatypes and the natural numbers;
  2007 
  2008 * the datatype declaration of type T now defines the recursor T_rec;
  2009 
  2010 * simplification automatically does freeness reasoning for datatype
  2011 constructors;
  2012 
  2013 * automatic type-inference, with AddTCs command to insert new
  2014 type-checking rules;
  2015 
  2016 * datatype introduction rules are now added as Safe Introduction rules
  2017 to the claset;
  2018 
  2019 * the syntax "if P then x else y" is now available in addition to
  2020 if(P,x,y);
  2021 
  2022 
  2023 *** Internal programming interfaces ***
  2024 
  2025 * tuned simplifier trace output; new flag debug_simp;
  2026 
  2027 * structures Vartab / Termtab (instances of TableFun) offer efficient
  2028 tables indexed by indexname_ord / term_ord (compatible with aconv);
  2029 
  2030 * AxClass.axclass_tac lost the theory argument;
  2031 
  2032 * tuned current_goals_markers semantics: begin / end goal avoids
  2033 printing empty lines;
  2034 
  2035 * removed prs and prs_fn hook, which was broken because it did not
  2036 include \n in its semantics, forcing writeln to add one
  2037 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  2038 string -> unit if you really want to output text without newline;
  2039 
  2040 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  2041 plain output, interface builders may have to enable 'isabelle_font'
  2042 mode to get Isabelle font glyphs as before;
  2043 
  2044 * refined token_translation interface; INCOMPATIBILITY: output length
  2045 now of type real instead of int;
  2046 
  2047 * theory loader actions may be traced via new ThyInfo.add_hook
  2048 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  2049 your own database of information attached to *whole* theories -- as
  2050 opposed to intra-theory data slots offered via TheoryDataFun;
  2051 
  2052 * proper handling of dangling sort hypotheses (at last!);
  2053 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  2054 extra sort hypotheses that can be witnessed from the type signature;
  2055 the force_strip_shyps flag is gone, any remaining shyps are simply
  2056 left in the theorem (with a warning issued by strip_shyps_warning);
  2057 
  2058 
  2059 
  2060 New in Isabelle98-1 (October 1998)
  2061 ----------------------------------
  2062 
  2063 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2064 
  2065 * several changes of automated proof tools;
  2066 
  2067 * HOL: major changes to the inductive and datatype packages, including
  2068 some minor incompatibilities of theory syntax;
  2069 
  2070 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  2071 called `inj_on';
  2072 
  2073 * HOL: removed duplicate thms in Arith:
  2074   less_imp_add_less  should be replaced by  trans_less_add1
  2075   le_imp_add_le      should be replaced by  trans_le_add1
  2076 
  2077 * HOL: unary minus is now overloaded (new type constraints may be
  2078 required);
  2079 
  2080 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  2081 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  2082 now taken as an integer constant.
  2083 
  2084 * Pure: ML function 'theory_of' renamed to 'theory';
  2085 
  2086 
  2087 *** Proof tools ***
  2088 
  2089 * Simplifier:
  2090   1. Asm_full_simp_tac is now more aggressive.
  2091      1. It will sometimes reorient premises if that increases their power to
  2092         simplify.
  2093      2. It does no longer proceed strictly from left to right but may also
  2094         rotate premises to achieve further simplification.
  2095      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  2096      old Asm_full_simp_tac in that it does not rotate premises.
  2097   2. The simplifier now knows a little bit about nat-arithmetic.
  2098 
  2099 * Classical reasoner: wrapper mechanism for the classical reasoner now
  2100 allows for selected deletion of wrappers, by introduction of names for
  2101 wrapper functionals.  This implies that addbefore, addSbefore,
  2102 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  2103 and that adding two tactics with the same name overwrites the first
  2104 one (emitting a warning).
  2105   type wrapper = (int -> tactic) -> (int -> tactic)
  2106   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  2107   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  2108   delWrapper, delSWrapper: claset *  string            -> claset
  2109   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  2110 
  2111 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  2112 semantics; addbefore now affects only the unsafe part of step_tac
  2113 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  2114 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  2115 by Force_tac;
  2116 
  2117 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  2118 compWrapper; added safe wrapper (and access functions for it);
  2119 
  2120 * HOL/split_all_tac is now much faster and fails if there is nothing
  2121 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  2122 and the names of the automatically generated variables have changed.
  2123 split_all_tac has moved within claset() from unsafe wrappers to safe
  2124 wrappers, which means that !!-bound variables are split much more
  2125 aggressively, and safe_tac and clarify_tac now split such variables.
  2126 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  2127 Note: the same holds for record_split_tac, which does the job of
  2128 split_all_tac for record fields.
  2129 
  2130 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  2131 permanently to the default simpset using Addsplits just like
  2132 Addsimps. They can be removed via Delsplits just like
  2133 Delsimps. Lower-case versions are also available.
  2134 
  2135 * HOL/Simplifier: The rule split_if is now part of the default
  2136 simpset. This means that the simplifier will eliminate all occurrences
  2137 of if-then-else in the conclusion of a goal. To prevent this, you can
  2138 either remove split_if completely from the default simpset by
  2139 `Delsplits [split_if]' or remove it in a specific call of the
  2140 simplifier using `... delsplits [split_if]'.  You can also add/delete
  2141 other case splitting rules to/from the default simpset: every datatype
  2142 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  2143 t is the name of the datatype).
  2144 
  2145 * Classical reasoner / Simplifier combination: new force_tac (and
  2146 derivatives Force_tac, force) combines rewriting and classical
  2147 reasoning (and whatever other tools) similarly to auto_tac, but is
  2148 aimed to solve the given subgoal completely.
  2149 
  2150 
  2151 *** General ***
  2152 
  2153 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  2154 and `goalw': the theory is no longer needed as an explicit argument -
  2155 the current theory context is used; assumptions are no longer returned
  2156 at the ML-level unless one of them starts with ==> or !!; it is
  2157 recommended to convert to these new commands using isatool fixgoal
  2158 (backup your sources first!);
  2159 
  2160 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  2161 the current theory context, and 'theory' to lookup stored theories;
  2162 
  2163 * new theory section 'locale' for declaring constants, assumptions and
  2164 definitions that have local scope;
  2165 
  2166 * new theory section 'nonterminals' for purely syntactic types;
  2167 
  2168 * new theory section 'setup' for generic ML setup functions
  2169 (e.g. package initialization);
  2170 
  2171 * the distribution now includes Isabelle icons: see
  2172 lib/logo/isabelle-{small,tiny}.xpm;
  2173 
  2174 * isatool install - install binaries with absolute references to
  2175 ISABELLE_HOME/bin;
  2176 
  2177 * isatool logo -- create instances of the Isabelle logo (as EPS);
  2178 
  2179 * print mode 'emacs' reserved for Isamode;
  2180 
  2181 * support multiple print (ast) translations per constant name;
  2182 
  2183 * theorems involving oracles are now printed with a suffixed [!];
  2184 
  2185 
  2186 *** HOL ***
  2187 
  2188 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  2189 
  2190 * HOL/inductive package reorganized and improved: now supports mutual
  2191 definitions such as
  2192 
  2193   inductive EVEN ODD
  2194     intrs
  2195       null "0 : EVEN"
  2196       oddI "n : EVEN ==> Suc n : ODD"
  2197       evenI "n : ODD ==> Suc n : EVEN"
  2198 
  2199 new theorem list "elims" contains an elimination rule for each of the
  2200 recursive sets; inductive definitions now handle disjunctive premises
  2201 correctly (also ZF);
  2202 
  2203 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  2204 "mutual_induct" no longer exists - the induction rule is always
  2205 contained in "induct";
  2206 
  2207 
  2208 * HOL/datatype package re-implemented and greatly improved: now
  2209 supports mutually recursive datatypes such as
  2210 
  2211   datatype
  2212     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  2213             | SUM ('a aexp) ('a aexp)
  2214             | DIFF ('a aexp) ('a aexp)
  2215             | NUM 'a
  2216   and
  2217     'a bexp = LESS ('a aexp) ('a aexp)
  2218             | AND ('a bexp) ('a bexp)
  2219             | OR ('a bexp) ('a bexp)
  2220 
  2221 as well as indirectly recursive datatypes such as
  2222 
  2223   datatype
  2224     ('a, 'b) term = Var 'a
  2225                   | App 'b ((('a, 'b) term) list)
  2226 
  2227 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  2228 induction on mutually / indirectly recursive datatypes.
  2229 
  2230 Primrec equations are now stored in theory and can be accessed via
  2231 <function_name>.simps.
  2232 
  2233 INCOMPATIBILITIES:
  2234 
  2235   - Theories using datatypes must now have theory Datatype as an
  2236     ancestor.
  2237   - The specific <typename>.induct_tac no longer exists - use the
  2238     generic induct_tac instead.
  2239   - natE has been renamed to nat.exhaust - use exhaust_tac
  2240     instead of res_inst_tac ... natE. Note that the variable
  2241     names in nat.exhaust differ from the names in natE, this
  2242     may cause some "fragile" proofs to fail.
  2243   - The theorems split_<typename>_case and split_<typename>_case_asm
  2244     have been renamed to <typename>.split and <typename>.split_asm.
  2245   - Since default sorts of type variables are now handled correctly,
  2246     some datatype definitions may have to be annotated with explicit
  2247     sort constraints.
  2248   - Primrec definitions no longer require function name and type
  2249     of recursive argument.
  2250 
  2251 Consider using isatool fixdatatype to adapt your theories and proof
  2252 scripts to the new package (backup your sources first!).
  2253 
  2254 
  2255 * HOL/record package: considerably improved implementation; now
  2256 includes concrete syntax for record types, terms, updates; theorems
  2257 for surjective pairing and splitting !!-bound record variables; proof
  2258 support is as follows:
  2259 
  2260   1) standard conversions (selectors or updates applied to record
  2261 constructor terms) are part of the standard simpset;
  2262 
  2263   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  2264 made part of standard simpset and claset via addIffs;
  2265 
  2266   3) a tactic for record field splitting (record_split_tac) is part of
  2267 the standard claset (addSWrapper);
  2268 
  2269 To get a better idea about these rules you may retrieve them via
  2270 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  2271 the name of your record type.
  2272 
  2273 The split tactic 3) conceptually simplifies by the following rule:
  2274 
  2275   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  2276 
  2277 Thus any record variable that is bound by meta-all will automatically
  2278 blow up into some record constructor term, consequently the
  2279 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  2280 solve record problems automatically.
  2281 
  2282 
  2283 * reorganized the main HOL image: HOL/Integ and String loaded by
  2284 default; theory Main includes everything;
  2285 
  2286 * automatic simplification of integer sums and comparisons, using cancellation;
  2287 
  2288 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  2289 
  2290 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  2291 
  2292 * many new identities for unions, intersections, set difference, etc.;
  2293 
  2294 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  2295 called split_if, split_split, split_sum_case and split_nat_case (to go
  2296 with add/delsplits);
  2297 
  2298 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  2299 (?x::unit) = (); this is made part of the default simpset, which COULD
  2300 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  2301 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  2302 unit_abs_eta_conv is added in order to counter the effect of
  2303 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  2304 %u.f();
  2305 
  2306 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  2307 makes more sense);
  2308 
  2309 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2310   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2311   disjointness reasoning but breaking a few old proofs.
  2312 
  2313 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  2314 to 'converse' from 'inverse' (for compatibility with ZF and some
  2315 literature);
  2316 
  2317 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  2318 the well-founded relation;
  2319 
  2320 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  2321     Compl A.  The "Compl" syntax remains available as input syntax for this
  2322     release ONLY.
  2323 
  2324 * HOL/Update: new theory of function updates:
  2325     f(a:=b) == %x. if x=a then b else f x
  2326 may also be iterated as in f(a:=b,c:=d,...);
  2327 
  2328 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  2329 
  2330 * HOL/List:
  2331   - new function list_update written xs[i:=v] that updates the i-th
  2332     list position. May also be iterated as in xs[i:=a,j:=b,...].
  2333   - new function `upt' written [i..j(] which generates the list
  2334     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  2335     bound write [i..j], which is a shorthand for [i..j+1(].
  2336   - new lexicographic orderings and corresponding wellfoundedness theorems.
  2337 
  2338 * HOL/Arith:
  2339   - removed 'pred' (predecessor) function;
  2340   - generalized some theorems about n-1;
  2341   - many new laws about "div" and "mod";
  2342   - new laws about greatest common divisors (see theory ex/Primes);
  2343 
  2344 * HOL/Relation: renamed the relational operator r^-1 "converse"
  2345 instead of "inverse";
  2346 
  2347 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  2348   of the multiset ordering;
  2349 
  2350 * directory HOL/Real: a construction of the reals using Dedekind cuts
  2351   (not included by default);
  2352 
  2353 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  2354 
  2355 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  2356   programs, i.e. different program variables may have different types.
  2357 
  2358 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2359   [previously, this check worked only if the rewrite rule was unconditional]
  2360   Now rew can involve either definitions or equalities (either == or =).
  2361 
  2362 
  2363 *** ZF ***
  2364 
  2365 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  2366   only the theorems proved on ZF.ML;
  2367 
  2368 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2369   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2370   disjointness reasoning but breaking a few old proofs.
  2371 
  2372 * ZF/Update: new theory of function updates
  2373     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  2374   may also be iterated as in f(a:=b,c:=d,...);
  2375 
  2376 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  2377 
  2378 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2379   [previously, this check worked only if the rewrite rule was unconditional]
  2380   Now rew can involve either definitions or equalities (either == or =).
  2381 
  2382 * case_tac provided for compatibility with HOL
  2383     (like the old excluded_middle_tac, but with subgoals swapped)
  2384 
  2385 
  2386 *** Internal programming interfaces ***
  2387 
  2388 * Pure: several new basic modules made available for general use, see
  2389 also src/Pure/README;
  2390 
  2391 * improved the theory data mechanism to support encapsulation (data
  2392 kind name replaced by private Object.kind, acting as authorization
  2393 key); new type-safe user interface via functor TheoryDataFun; generic
  2394 print_data function becomes basically useless;
  2395 
  2396 * removed global_names compatibility flag -- all theory declarations
  2397 are qualified by default;
  2398 
  2399 * module Pure/Syntax now offers quote / antiquote translation
  2400 functions (useful for Hoare logic etc. with implicit dependencies);
  2401 see HOL/ex/Antiquote for an example use;
  2402 
  2403 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2404 cterm -> thm;
  2405 
  2406 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2407 subgoal;
  2408 
  2409 * Display.print_goals function moved to Locale.print_goals;
  2410 
  2411 * standard print function for goals supports current_goals_markers
  2412 variable for marking begin of proof, end of proof, start of goal; the
  2413 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2414 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2415 for example;
  2416 
  2417 
  2418 
  2419 New in Isabelle98 (January 1998)
  2420 --------------------------------
  2421 
  2422 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2423 
  2424 * changed lexical syntax of terms / types: dots made part of long
  2425 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2426 
  2427 * simpset (and claset) reference variable replaced by functions
  2428 simpset / simpset_ref;
  2429 
  2430 * no longer supports theory aliases (via merge) and non-trivial
  2431 implicit merge of thms' signatures;
  2432 
  2433 * most internal names of constants changed due to qualified names;
  2434 
  2435 * changed Pure/Sequence interface (see Pure/seq.ML);
  2436 
  2437 
  2438 *** General Changes ***
  2439 
  2440 * hierachically structured name spaces (for consts, types, axms, thms
  2441 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2442 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2443 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2444 long_names for fully qualified output names; NOTE: ML programs
  2445 (special tactics, packages etc.) referring to internal names may have
  2446 to be adapted to cope with fully qualified names; in case of severe
  2447 backward campatibility problems try setting 'global_names' at compile
  2448 time to have enrything declared within a flat name space; one may also
  2449 fine tune name declarations in theories via the 'global' and 'local'
  2450 section;
  2451 
  2452 * reimplemented the implicit simpset and claset using the new anytype
  2453 data filed in signatures; references simpset:simpset ref etc. are
  2454 replaced by functions simpset:unit->simpset and
  2455 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2456 to patch your ML files accordingly;
  2457 
  2458 * HTML output now includes theory graph data for display with Java
  2459 applet or isatool browser; data generated automatically via isatool
  2460 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2461 
  2462 * defs may now be conditional; improved rewrite_goals_tac to handle
  2463 conditional equations;
  2464 
  2465 * defs now admits additional type arguments, using TYPE('a) syntax;
  2466 
  2467 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2468 creates a new theory node; implicit merge of thms' signatures is
  2469 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2470 transfer:theory->thm->thm in (rare) cases;
  2471 
  2472 * improved handling of draft signatures / theories; draft thms (and
  2473 ctyps, cterms) are automatically promoted to real ones;
  2474 
  2475 * slightly changed interfaces for oracles: admit many per theory, named
  2476 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2477 
  2478 * print_goals: optional output of const types (set show_consts and
  2479 show_types);
  2480 
  2481 * improved output of warnings (###) and errors (***);
  2482 
  2483 * subgoal_tac displays a warning if the new subgoal has type variables;
  2484 
  2485 * removed old README and Makefiles;
  2486 
  2487 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2488 
  2489 * removed obsolete init_pps and init_database;
  2490 
  2491 * deleted the obsolete tactical STATE, which was declared by
  2492     fun STATE tacfun st = tacfun st st;
  2493 
  2494 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2495 (which abbreviates $HOME);
  2496 
  2497 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2498 use isatool fixseq to adapt your ML programs (this works for fully
  2499 qualified references to the Sequence structure only!);
  2500 
  2501 * use_thy no longer requires writable current directory; it always
  2502 reloads .ML *and* .thy file, if either one is out of date;
  2503 
  2504 
  2505 *** Classical Reasoner ***
  2506 
  2507 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2508 tactics that use classical reasoning to simplify a subgoal without
  2509 splitting it into several subgoals;
  2510 
  2511 * Safe_tac: like safe_tac but uses the default claset;
  2512 
  2513 
  2514 *** Simplifier ***
  2515 
  2516 * added simplification meta rules:
  2517     (asm_)(full_)simplify: simpset -> thm -> thm;
  2518 
  2519 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2520 logics (again);
  2521 
  2522 * added prems argument to simplification procedures;
  2523 
  2524 * HOL, FOL, ZF: added infix function `addsplits':
  2525   instead of `<simpset> setloop (split_tac <thms>)'
  2526   you can simply write `<simpset> addsplits <thms>'
  2527 
  2528 
  2529 *** Syntax ***
  2530 
  2531 * TYPE('a) syntax for type reflection terms;
  2532 
  2533 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2534 
  2535 * pretty printer: changed order of mixfix annotation preference (again!);
  2536 
  2537 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2538 
  2539 
  2540 *** HOL ***
  2541 
  2542 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2543   with `addloop' of the simplifier to faciliate case splitting in premises.
  2544 
  2545 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2546 
  2547 * HOL/Auth: new protocol proofs including some for the Internet
  2548   protocol TLS;
  2549 
  2550 * HOL/Map: new theory of `maps' a la VDM;
  2551 
  2552 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2553 cancelling out common nat summands from =, <, <= (in)equalities, or
  2554 differences; simplification procedures nat_cancel_factor for
  2555 cancelling common factor from =, <, <= (in)equalities over natural
  2556 sums; nat_cancel contains both kinds of procedures, it is installed by
  2557 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2558 
  2559 * HOL/simplifier: terms of the form
  2560   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2561   are rewritten to
  2562   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2563   and those of the form
  2564   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2565   are rewritten to
  2566   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2567 
  2568 * HOL/datatype
  2569   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2570 
  2571   P(t_case f1 ... fn x) =
  2572      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2573         ...
  2574        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2575      )
  2576 
  2577   and a theorem `split_t_case_asm' of the form
  2578 
  2579   P(t_case f1 ... fn x) =
  2580     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2581         ...
  2582        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2583      )
  2584   which can be added to a simpset via `addsplits'. The existing theorems
  2585   expand_list_case and expand_option_case have been renamed to
  2586   split_list_case and split_option_case.
  2587 
  2588 * HOL/Arithmetic:
  2589   - `pred n' is automatically converted to `n-1'.
  2590     Users are strongly encouraged not to use `pred' any longer,
  2591     because it will disappear altogether at some point.
  2592   - Users are strongly encouraged to write "0 < n" rather than
  2593     "n ~= 0". Theorems and proof tools have been modified towards this
  2594     `standard'.
  2595 
  2596 * HOL/Lists:
  2597   the function "set_of_list" has been renamed "set" (and its theorems too);
  2598   the function "nth" now takes its arguments in the reverse order and
  2599   has acquired the infix notation "!" as in "xs!n".
  2600 
  2601 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2602 
  2603 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2604   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2605 
  2606 * HOL/record: extensible records with schematic structural subtyping
  2607 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2608 still lacks various theorems and concrete record syntax;
  2609 
  2610 
  2611 *** HOLCF ***
  2612 
  2613 * removed "axioms" and "generated by" sections;
  2614 
  2615 * replaced "ops" section by extended "consts" section, which is capable of
  2616   handling the continuous function space "->" directly;
  2617 
  2618 * domain package:
  2619   . proves theorems immediately and stores them in the theory,
  2620   . creates hierachical name space,
  2621   . now uses normal mixfix annotations (instead of cinfix...),
  2622   . minor changes to some names and values (for consistency),
  2623   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2624   . separator between mutual domain defs: changed "," to "and",
  2625   . improved handling of sort constraints;  now they have to
  2626     appear on the left-hand side of the equations only;
  2627 
  2628 * fixed LAM <x,y,zs>.b syntax;
  2629 
  2630 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2631 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2632 
  2633 
  2634 *** FOL and ZF ***
  2635 
  2636 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2637   with `addloop' of the simplifier to faciliate case splitting in premises.
  2638 
  2639 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2640 in HOL, they strip ALL and --> from proved theorems;
  2641 
  2642 
  2643 
  2644 New in Isabelle94-8 (May 1997)
  2645 ------------------------------
  2646 
  2647 *** General Changes ***
  2648 
  2649 * new utilities to build / run / maintain Isabelle etc. (in parts
  2650 still somewhat experimental); old Makefiles etc. still functional;
  2651 
  2652 * new 'Isabelle System Manual';
  2653 
  2654 * INSTALL text, together with ./configure and ./build scripts;
  2655 
  2656 * reimplemented type inference for greater efficiency, better error
  2657 messages and clean internal interface;
  2658 
  2659 * prlim command for dealing with lots of subgoals (an easier way of
  2660 setting goals_limit);
  2661 
  2662 
  2663 *** Syntax ***
  2664 
  2665 * supports alternative (named) syntax tables (parser and pretty
  2666 printer); internal interface is provided by add_modesyntax(_i);
  2667 
  2668 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2669 be used in conjunction with the Isabelle symbol font; uses the
  2670 "symbols" syntax table;
  2671 
  2672 * added token_translation interface (may translate name tokens in
  2673 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2674 the current print_mode); IMPORTANT: user print translation functions
  2675 are responsible for marking newly introduced bounds
  2676 (Syntax.mark_boundT);
  2677 
  2678 * token translations for modes "xterm" and "xterm_color" that display
  2679 names in bold, underline etc. or colors (which requires a color
  2680 version of xterm);
  2681 
  2682 * infixes may now be declared with names independent of their syntax;
  2683 
  2684 * added typed_print_translation (like print_translation, but may
  2685 access type of constant);
  2686 
  2687 
  2688 *** Classical Reasoner ***
  2689 
  2690 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2691 some limitations.  Blast_tac...
  2692   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2693   + ignores elimination rules that don't have the correct format
  2694         (the conclusion MUST be a formula variable)
  2695   + ignores types, which can make HOL proofs fail
  2696   + rules must not require higher-order unification, e.g. apply_type in ZF
  2697     [message "Function Var's argument not a bound variable" relates to this]
  2698   + its proof strategy is more general but can actually be slower
  2699 
  2700 * substitution with equality assumptions no longer permutes other
  2701 assumptions;
  2702 
  2703 * minor changes in semantics of addafter (now called addaltern); renamed
  2704 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2705 (and access functions for it);
  2706 
  2707 * improved combination of classical reasoner and simplifier:
  2708   + functions for handling clasimpsets
  2709   + improvement of addss: now the simplifier is called _after_ the
  2710     safe steps.
  2711   + safe variant of addss called addSss: uses safe simplifications
  2712     _during_ the safe steps. It is more complete as it allows multiple
  2713     instantiations of unknowns (e.g. with slow_tac).
  2714 
  2715 *** Simplifier ***
  2716 
  2717 * added interface for simplification procedures (functions that
  2718 produce *proven* rewrite rules on the fly, depending on current
  2719 redex);
  2720 
  2721 * ordering on terms as parameter (used for ordered rewriting);
  2722 
  2723 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2724 
  2725 * the solver is now split into a safe and an unsafe part.
  2726 This should be invisible for the normal user, except that the
  2727 functions setsolver and addsolver have been renamed to setSolver and
  2728 addSolver; added safe_asm_full_simp_tac;
  2729 
  2730 
  2731 *** HOL ***
  2732 
  2733 * a generic induction tactic `induct_tac' which works for all datatypes and
  2734 also for type `nat';
  2735 
  2736 * a generic case distinction tactic `exhaust_tac' which works for all
  2737 datatypes and also for type `nat';
  2738 
  2739 * each datatype comes with a function `size';
  2740 
  2741 * patterns in case expressions allow tuple patterns as arguments to
  2742 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2743 
  2744 * primrec now also works with type nat;
  2745 
  2746 * recdef: a new declaration form, allows general recursive functions to be
  2747 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2748 
  2749 * the constant for negation has been renamed from "not" to "Not" to
  2750 harmonize with FOL, ZF, LK, etc.;
  2751 
  2752 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2753 infinite lists;
  2754 
  2755 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2756 
  2757 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2758 problems in commutative rings, using axiomatic type classes for + and *;
  2759 
  2760 * more examples in HOL/MiniML and HOL/Auth;
  2761 
  2762 * more default rewrite rules for quantifiers, union/intersection;
  2763 
  2764 * a new constant `arbitrary == @x.False';
  2765 
  2766 * HOLCF/IOA replaces old HOL/IOA;
  2767 
  2768 * HOLCF changes: derived all rules and arities
  2769   + axiomatic type classes instead of classes
  2770   + typedef instead of faking type definitions
  2771   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2772   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2773   + eliminated the types void, one, tr
  2774   + use unit lift and bool lift (with translations) instead of one and tr
  2775   + eliminated blift from Lift3.thy (use Def instead of blift)
  2776   all eliminated rules are derived as theorems --> no visible changes ;
  2777 
  2778 
  2779 *** ZF ***
  2780 
  2781 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2782 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2783 as ZF_cs addSIs [equalityI];
  2784 
  2785 
  2786 
  2787 New in Isabelle94-7 (November 96)
  2788 ---------------------------------
  2789 
  2790 * allowing negative levels (as offsets) in prlev and choplev;
  2791 
  2792 * super-linear speedup for large simplifications;
  2793 
  2794 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2795 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2796 FAIL); can suppress it using the command Delsimps (ex_simps @
  2797 all_simps); De Morgan laws are also now included, by default;
  2798 
  2799 * improved printing of ==>  :  ~:
  2800 
  2801 * new object-logic "Sequents" adds linear logic, while replacing LK
  2802 and Modal (thanks to Sara Kalvala);
  2803 
  2804 * HOL/Auth: correctness proofs for authentication protocols;
  2805 
  2806 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2807 examples on HOL/Auth);
  2808 
  2809 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2810 the rewriter and classical reasoner simultaneously;
  2811 
  2812 * function uresult no longer returns theorems in "standard" format;
  2813 regain previous version by: val uresult = standard o uresult;
  2814 
  2815 
  2816 
  2817 New in Isabelle94-6
  2818 -------------------
  2819 
  2820 * oracles -- these establish an interface between Isabelle and trusted
  2821 external reasoners, which may deliver results as theorems;
  2822 
  2823 * proof objects (in particular record all uses of oracles);
  2824 
  2825 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2826 
  2827 * "constdefs" section in theory files;
  2828 
  2829 * "primrec" section (HOL) no longer requires names;
  2830 
  2831 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2832 
  2833 
  2834 
  2835 New in Isabelle94-5
  2836 -------------------
  2837 
  2838 * reduced space requirements;
  2839 
  2840 * automatic HTML generation from theories;
  2841 
  2842 * theory files no longer require "..." (quotes) around most types;
  2843 
  2844 * new examples, including two proofs of the Church-Rosser theorem;
  2845 
  2846 * non-curried (1994) version of HOL is no longer distributed;
  2847 
  2848 
  2849 
  2850 New in Isabelle94-4
  2851 -------------------
  2852 
  2853 * greatly reduced space requirements;
  2854 
  2855 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2856 
  2857 * searchable theorem database (see the section "Retrieving theorems" on
  2858 page 8 of the Reference Manual);
  2859 
  2860 * new examples, including Grabczewski's monumental case study of the
  2861 Axiom of Choice;
  2862 
  2863 * The previous version of HOL renamed to Old_HOL;
  2864 
  2865 * The new version of HOL (previously called CHOL) uses a curried syntax
  2866 for functions.  Application looks like f a b instead of f(a,b);
  2867 
  2868 * Mutually recursive inductive definitions finally work in HOL;
  2869 
  2870 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2871 translates to the operator "split";
  2872 
  2873 
  2874 
  2875 New in Isabelle94-3
  2876 -------------------
  2877 
  2878 * new infix operator, addss, allowing the classical reasoner to
  2879 perform simplification at each step of its search.  Example:
  2880         fast_tac (cs addss ss)
  2881 
  2882 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2883 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2884 look like (a,b) instead of <a,b>;
  2885 
  2886 * PLEASE NOTE: CHOL will eventually replace HOL!
  2887 
  2888 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2889 It translates to the operator "split".  A new theory of integers is available;
  2890 
  2891 * In ZF, integer numerals now denote two's-complement binary integers.
  2892 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2893 
  2894 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2895 of the Axiom of Choice;
  2896 
  2897 
  2898 
  2899 New in Isabelle94-2
  2900 -------------------
  2901 
  2902 * Significantly faster resolution;
  2903 
  2904 * the different sections in a .thy file can now be mixed and repeated
  2905 freely;
  2906 
  2907 * Database of theorems for FOL, HOL and ZF.  New
  2908 commands including qed, qed_goal and bind_thm store theorems in the database.
  2909 
  2910 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2911 a given theory (thms_of), or find out what theory a theorem was proved in
  2912 (theory_of_thm);
  2913 
  2914 * Bugs fixed in the inductive definition and datatype packages;
  2915 
  2916 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2917 and HOL_dup_cs obsolete;
  2918 
  2919 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2920 have been removed;
  2921 
  2922 * Simpler definition of function space in ZF;
  2923 
  2924 * new results about cardinal and ordinal arithmetic in ZF;
  2925 
  2926 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2927 types;
  2928 
  2929 
  2930 $Id$