NEWS
author kleing
Mon May 16 09:35:05 2005 +0200 (2005-05-16)
changeset 15964 f2074e12d1d4
parent 15931 8d2fdcc558d1
child 15973 5fd94d84470f
permissions -rw-r--r--
searching for thms by combination of criteria (intro, elim, dest, name, term pattern)
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** General ***
     8 
     9 * ML: The type Library.option is no more, along with the exception
    10   Library.OPTION: Isabelle now uses the standard option type.  The
    11   functions the, is_some, is_none, etc. are still in Library, but
    12   the constructors are now SOME and NONE instead of Some and None.
    13   They raise the exception Option.
    14 
    15 * ML: The exception LIST is no more, the standard exceptions Empty and
    16   Subscript, as well as Library.UnequalLengths are used instead.  This
    17   means that function like Library.hd and Library.tl are gone, as the
    18   standard hd and tl functions suffice.
    19 
    20   A number of basic functions are now no longer exported to the top ML
    21   level, as they are variants of standard functions.  The following
    22   suggests how one can translate existing code:
    23 
    24     the x = valOf x
    25     if_none x y = getOpt(x,y)
    26     is_some x = isSome x
    27     apsome f x = Option.map f x
    28     rev_append xs ys = List.revAppend(xs,ys)
    29     nth_elem(i,xs) = List.nth(xs,i)
    30     last_elem xs = List.last xs
    31     flat xss = List.concat xss
    32     seq fs = app fs
    33     partition P xs = List.partition P xs
    34     filter P xs = List.filter P xs
    35     mapfilter f xs = List.mapPartial f xs
    36 
    37   The final four functions, take, drop, foldl, and foldr, are somewhat
    38   more complicated (especially the semantics of take and drop differ
    39   from the standard).
    40 
    41   A simple solution to broken code is to include "open Library" at the
    42   beginning of a structure.  Everything after that will be as before.
    43 
    44 * Theory headers: the new header syntax for Isar theories is
    45 
    46   theory <name>
    47   imports <theory1> ... <theoryn>
    48   begin
    49 
    50   optionally also with a "files" section. The syntax
    51 
    52   theory <name> = <theory1> + ... + <theoryn>:
    53 
    54   will still be supported for some time but will eventually disappear.
    55   The syntax of old-style theories has not changed.
    56 
    57 * Theory loader: parent theories can now also be referred to via
    58   relative and absolute paths.
    59 
    60 * Provers/quasi.ML:  new transitivity reasoners for transitivity only
    61   and quasi orders.
    62 
    63 * Provers/trancl.ML:  new transitivity reasoner for transitive and
    64   reflexive-transitive closure of relations.
    65 
    66 * Provers/blast.ML:  new reference depth_limit to make blast's depth
    67   limit (previously hard-coded with a value of 20) user-definable.
    68 
    69 * Provers: new version of the subst method, for single-step rewriting: it now
    70   works in bound variable contexts. New is subst (asm), for rewriting an
    71   assumption. Thanks to Lucas Dixon! INCOMPATIBILITY: may rewrite a different
    72   subterm than the original subst method, which is still available under the
    73   name simplesubst.
    74 
    75 * Pure: thin_tac now works even if the assumption being deleted contains !! or ==>. 
    76   More generally, erule now works even if the major premise of the elimination rule
    77   contains !! or ==>.
    78 
    79 * Pure: considerably improved version of 'constdefs' command.  Now
    80   performs automatic type-inference of declared constants; additional
    81   support for local structure declarations (cf. locales and HOL
    82   records), see also isar-ref manual.  Potential INCOMPATIBILITY: need
    83   to observe strictly sequential dependencies of definitions within a
    84   single 'constdefs' section; moreover, the declared name needs to be
    85   an identifier.  If all fails, consider to fall back on 'consts' and
    86   'defs' separately.
    87 
    88 * Pure: improved indexed syntax and implicit structures.  First of
    89   all, indexed syntax provides a notational device for subscripted
    90   application, using the new syntax \<^bsub>term\<^esub> for arbitrary
    91   expressions.  Secondly, in a local context with structure
    92   declarations, number indexes \<^sub>n or the empty index (default
    93   number 1) refer to a certain fixed variable implicitly; option
    94   show_structs controls printing of implicit structures.  Typical
    95   applications of these concepts involve record types and locales.
    96 
    97 * Pure: clear separation of logical types and nonterminals, where the
    98   latter may only occur in 'syntax' specifications or type
    99   abbreviations.  Before that distinction was only partially
   100   implemented via type class "logic" vs. "{}".  Potential
   101   INCOMPATIBILITY in rare cases of improper use of 'types'/'consts'
   102   instead of 'nonterminals'/'syntax'.  Some very exotic syntax
   103   specifications may require further adaption (e.g. Cube/Base.thy).
   104 
   105 * Pure: removed obsolete type class "logic", use the top sort {}
   106   instead.  Note that non-logical types should be declared as
   107   'nonterminals' rather than 'types'.  INCOMPATIBILITY for new
   108   object-logic specifications.
   109 
   110 * Pure: command 'no_syntax' removes grammar declarations (and
   111   translations) resulting from the given syntax specification, which
   112   is interpreted in the same manner as for the 'syntax' command.
   113 
   114 * Pure: print_tac now outputs the goal through the trace channel.
   115 
   116 * Pure: reference Namespace.unique_names included.  If true the
   117   (shortest) namespace-prefix is printed to disambiguate conflicts (as
   118   yet). If false the first entry wins (as during parsing). Default
   119   value is true.
   120 
   121 * Pure: tuned internal renaming of symbolic identifiers -- attach
   122   primes instead of base 26 numbers.
   123 
   124 * Pure: new flag show_var_qmarks to control printing of leading
   125   question marks of variable names.
   126 
   127 * Pure: new version of thms_containing that searches for a list 
   128   of patterns instead of a list of constants. Available in 
   129   ProofGeneral under ProofGeneral -> Find Theorems or C-c C-f. 
   130   Example search: "(_::nat) + _ + _"   "_ ==> _"
   131 
   132 * Pure/Syntax: inner syntax includes (*(*nested*) comments*).
   133 
   134 * Pure/Syntax: pretty pinter now supports unbreakable blocks,
   135   specified in mixfix annotations as "(00...)".
   136 
   137 * Pure/Syntax: 'advanced' translation functions (parse_translation
   138   etc.) may depend on the signature of the theory context being
   139   presently used for parsing/printing, see also isar-ref manual.
   140 
   141 * Pure/Simplifier: simplification procedures may now take the current
   142   simpset into account (cf. Simplifier.simproc(_i) / mk_simproc
   143   interface), which is very useful for calling the Simplifier
   144   recursively.  Minor INCOMPATIBILITY: the 'prems' argument of
   145   simprocs is gone -- use prems_of_ss on the simpset instead.
   146   Moreover, the low-level mk_simproc no longer applies Logic.varify
   147   internally, to allow for use in a context of fixed variables.
   148 
   149 * Pure/Simplifier: Command "find_rewrites" takes a string and lists all
   150   equality theorems (not just those declared as simp!) whose left-hand
   151   side matches the term given via the string. In PG the command can be
   152   activated via Isabelle -> Show me -> matching rewrites.
   153 
   154 * Isar debugging: new reference Toplevel.debug; default false.
   155   Set to make printing of exceptions THM, TERM, TYPE and THEORY more verbose.
   156   
   157 * Locales:
   158   - "includes" disallowed in declaration of named locales (command "locale").
   159   - Fixed parameter management in theorem generation for goals with "includes".
   160     INCOMPATIBILITY: rarely, the generated theorem statement is different.
   161 
   162 * Locales:  new commands for the interpretation of locale expressions
   163   in theories (interpretation) and proof contexts (interpret).  These take an
   164   instantiation of the locale parameters and compute proof obligations from
   165   the instantiated specification.  After the obligations have been discharged,
   166   the instantiated theorems of the locale are added to the theory or proof
   167   context.  Interpretation is smart in that already active interpretations
   168   do not occur in proof obligations, neither are instantiated theorems stored
   169   in duplicate.
   170   Use print_interps to inspect active interpretations of a particular locale.
   171   For details, see the Isar Reference manual.
   172 
   173 * Locales: proper static binding of attribute syntax -- i.e. types /
   174   terms / facts mentioned as arguments are always those of the locale
   175   definition context, independently of the context of later
   176   invocations.  Moreover, locale operations (renaming and type / term
   177   instantiation) are applied to attribute arguments as expected.
   178 
   179   INCOMPATIBILITY of the ML interface: always pass Attrib.src instead
   180   of actual attributes; rare situations may require Attrib.attribute
   181   to embed those attributes into Attrib.src that lack concrete syntax.
   182 
   183   Attribute implementations need to cooperate properly with the static
   184   binding mechanism.  Basic parsers Args.XXX_typ/term/prop and
   185   Attrib.XXX_thm etc. already do the right thing without further
   186   intervention.  Only unusual applications -- such as "where" or "of"
   187   (cf. src/Pure/Isar/attrib.ML), which process arguments depending
   188   both on the context and the facts involved -- may have to assign
   189   parsed values to argument tokens explicitly.
   190 
   191 * Attributes 'induct' and 'cases': type or set names may now be
   192   locally fixed variables as well.
   193 
   194 * Isar: new syntax 'name(i-j, i-, i, ...)' for referring to specific
   195   selections of theorems in named facts via indices.
   196 
   197 * Pure: reorganized bootstrapping of the Pure theories; CPure is now
   198   derived from Pure, which contains all common declarations already.
   199   Both theories are defined via plain Isabelle/Isar .thy files.
   200   INCOMPATIBILITY: elements of CPure (such as the CPure.intro /
   201   CPure.elim / CPure.dest attributes) now appear in the Pure name
   202   space; use isatool fixcpure to adapt your theory and ML sources.
   203 
   204 
   205 *** Document preparation ***
   206 
   207 * New antiquotation @{term_type term} printing a term with its
   208   type annotated
   209 
   210 * New antiquotation @{typeof term} printing the - surprise - the type of 
   211   a term
   212 
   213 * New antiquotation @{const const} which is the same as @{term const} except
   214   that const must be a defined constant identifier; helpful for early detection
   215   of typoes
   216 
   217 * Two new antiquotations @{term_style style term} and @{thm_style style thm}
   218   which print a term / theorem applying a "style" to it; predefined styles
   219   are "lhs" and "rhs" printing the lhs/rhs of definitions, equations,
   220   inequations etc. and "conclusion" printing only the conclusion of a theorem.
   221   More styles may be defined using ML; see the "LaTeX Sugar" document for more
   222 
   223 * Antiquotations now provide the option 'locale=NAME' to specify an
   224   alternative context used for evaluating and printing the subsequent
   225   argument, as in @{thm [locale=LC] fold_commute}, for example.
   226 
   227 * Commands 'display_drafts' and 'print_drafts' perform simple output
   228   of raw sources.  Only those symbols that do not require additional
   229   LaTeX packages (depending on comments in isabellesym.sty) are
   230   displayed properly, everything else is left verbatim.  We use
   231   isatool display and isatool print as front ends; these are subject
   232   to the DVI/PDF_VIEWER and PRINT_COMMAND settings, respectively.
   233 
   234 * Proof scripts as well as some other commands such as ML or
   235   parse/print_translation can now be hidden in the document.  Hiding
   236   is enabled by default, and can be disabled either via the option '-H
   237   false' of isatool usedir or by resetting the reference variable
   238   IsarOutput.hide_commands. Additional commands to be hidden may be
   239   declared using IsarOutput.add_hidden_commands.
   240 
   241 
   242 *** HOL ***
   243 
   244 * Datatype induction via method `induct' now preserves the name of the
   245   induction variable. For example, when proving P(xs::'a list) by induction
   246   on xs, the induction step is now P(xs) ==> P(a#xs) rather than
   247   P(list) ==> P(a#list) as previously.
   248 
   249 * HOL/record: reimplementation of records. Improved scalability for
   250   records with many fields, avoiding performance problems for type
   251   inference. Records are no longer composed of nested field types, but
   252   of nested extension types. Therefore the record type only grows
   253   linear in the number of extensions and not in the number of fields.
   254   The top-level (users) view on records is preserved.  Potential
   255   INCOMPATIBILITY only in strange cases, where the theory depends on
   256   the old record representation. The type generated for a record is
   257   called <record_name>_ext_type.
   258 
   259 * HOL/record: Reference record_quick_and_dirty_sensitive can be
   260   enabled to skip the proofs triggered by a record definition or a
   261   simproc (if quick_and_dirty is enabled). Definitions of large
   262   records can take quite long.
   263 
   264 * HOL/record: "record_upd_simproc" for simplification of multiple
   265   record updates enabled by default.  Moreover, trivial updates are
   266   also removed: r(|x := x r|) = r.  INCOMPATIBILITY: old proofs break
   267   occasionally, since simplification is more powerful by default.
   268 
   269 * HOL: symbolic syntax of Hilbert Choice Operator is now as follows:
   270 
   271   syntax (epsilon)
   272     "_Eps" :: "[pttrn, bool] => 'a"    ("(3\<some>_./ _)" [0, 10] 10)
   273 
   274   The symbol \<some> is displayed as the alternative epsilon of LaTeX
   275   and x-symbol; use option '-m epsilon' to get it actually printed.
   276   Moreover, the mathematically important symbolic identifier
   277   \<epsilon> becomes available as variable, constant etc.
   278 
   279 * HOL: "x > y" abbreviates "y < x" and "x >= y" abbreviates "y <= x".
   280   Similarly for all quantifiers: "ALL x > y" etc.
   281   The x-symbol for >= is \<ge>.
   282 
   283 * HOL/Set: "{x:A. P}" abbreviates "{x. x:A & P}"
   284            (and similarly for "\<in>" instead of ":")
   285 
   286 * HOL/SetInterval: The syntax for open intervals has changed:
   287 
   288   Old         New
   289   {..n(}   -> {..<n}
   290   {)n..}   -> {n<..}
   291   {m..n(}  -> {m..<n}
   292   {)m..n}  -> {m<..n}
   293   {)m..n(} -> {m<..<n}
   294 
   295   The old syntax is still supported but will disappear in the future.
   296   For conversion use the following emacs search and replace patterns:
   297 
   298   {)\([^\.]*\)\.\.  ->  {\1<\.\.}
   299   \.\.\([^(}]*\)(}  ->  \.\.<\1}
   300 
   301   They are not perfect but work quite well.
   302 
   303 * HOL: The syntax for 'setsum', summation over finite sets, has changed:
   304 
   305   The syntax for 'setsum (%x. e) A' used to be '\<Sum>x:A. e'
   306   and is now either 'SUM x:A. e' or '\<Sum>x\<in>A. e'.
   307 
   308   There is new syntax for summation over finite sets:
   309 
   310   '\<Sum>x | P. e'    is the same as  'setsum (%x. e) {x. P}'
   311   '\<Sum>x=a..b. e'   is the same as  'setsum (%x. e) {a..b}'
   312   '\<Sum>x=a..<b. e'  is the same as  'setsum (%x. e) {a..<b}'
   313   '\<Sum>x<k. e'      is the same as  'setsum (%x. e) {..<k}'
   314 
   315   Function 'Summation' over nat is gone, its syntax '\<Sum>i<k. e'
   316   now translates into 'setsum' as above.
   317 
   318 * HOL: Finite set induction: In Isar proofs, the insert case is now
   319   "case (insert x F)" instead of the old counterintuitive "case (insert F x)".
   320 
   321 * HOL/Simplifier:
   322 
   323   - Is now set up to reason about transitivity chains involving "trancl"
   324   (r^+) and "rtrancl" (r^*) by setting up tactics provided by
   325   Provers/trancl.ML as additional solvers.  INCOMPATIBILITY: old proofs break
   326   occasionally as simplification may now solve more goals than previously.
   327 
   328   - Converts x <= y into x = y if assumption y <= x is present.  Works for
   329   all partial orders (class "order"), in particular numbers and sets. For
   330   linear orders (e.g. numbers) it treats ~ x < y just like y <= x.
   331 
   332   - Simproc for "let x = a in f x"
   333   If a is a free or bound variable or a constant then the let is unfolded.
   334   Otherwise first a is simplified to a', and then f a' is simplified to
   335   g. If possible we abstract a' from g arriving at "let x = a' in g' x",
   336   otherwise we unfold the let and arrive at g. The simproc can be 
   337   enabled/disabled by the reference use_let_simproc. Potential
   338   INCOMPATIBILITY since simplification is more powerful by default.
   339 
   340 * HOL: The 'refute' command has been extended to support a much larger
   341   fragment of HOL, including axiomatic type classes, constdefs and typedefs,
   342   inductive datatypes and recursion.
   343 
   344 
   345 *** HOLCF ***
   346 
   347 * HOLCF: discontinued special version of 'constdefs' (which used to
   348   support continuous functions) in favor of the general Pure one with
   349   full type-inference.
   350 
   351 
   352 *** ZF ***
   353 
   354 * ZF/ex/{Group,Ring}: examples in abstract algebra, including the
   355   First Isomorphism Theorem (on quotienting by the kernel of a
   356   homomorphism).
   357 
   358 * ZF/Simplifier: install second copy of type solver that actually
   359   makes use of TC rules declared to Isar proof contexts (or locales);
   360   the old version is still required for ML proof scripts.
   361 
   362 
   363 *** System ***
   364 
   365 * Allow symlinks to all proper Isabelle executables (Isabelle,
   366   isabelle, isatool etc.).
   367 
   368 * isabelle-process: Poly/ML no longer needs Perl to run an interactive
   369   session.
   370 
   371 * ISABELLE_DOC_FORMAT setting specifies preferred document format (for
   372   isatool doc, isatool mkdir, display_drafts etc.).
   373 
   374 * isatool usedir: option -f allows specification of the ML file to be
   375   used by Isabelle; default is ROOT.ML.
   376 
   377 * HOL: isatool dimacs2hol converts files in DIMACS CNF format
   378   (containing Boolean satisfiability problems) into Isabelle/HOL
   379   theories.
   380 
   381 
   382 *** ML ***
   383 
   384 * Pure: output via the Isabelle channels of writeln/warning/error
   385   etc. is now passed through Output.output, with a hook for arbitrary
   386   transformations depending on the print_mode (cf. Output.add_mode --
   387   the first active mode that provides a output function wins).
   388   Already formatted output may be embedded into further text via
   389   Output.raw; the result of Pretty.string_of/str_of and derived
   390   functions (string_of_term/cterm/thm etc.) is already marked raw to
   391   accommodate easy composition of diagnostic messages etc.
   392   Programmers rarely need to care about Output.output or Output.raw at
   393   all, with some notable exceptions: Output.output is required when
   394   bypassing the standard channels (writeln etc.), or in token
   395   translations to produce properly formatted results; Output.raw is
   396   required when capturing already output material that will eventually
   397   be presented to the user a second time.  For the default print mode,
   398   both Output.output and Output.raw have no effect.
   399 
   400 * Provers: Simplifier and Classical Reasoner now support proof context
   401   dependent plug-ins (simprocs, solvers, wrappers etc.).  These extra
   402   components are stored in the theory and patched into the
   403   simpset/claset when used in an Isar proof context.  Context
   404   dependent components are maintained by the following theory
   405   operations:
   406 
   407     Simplifier.add_context_simprocs
   408     Simplifier.del_context_simprocs
   409     Simplifier.set_context_subgoaler
   410     Simplifier.reset_context_subgoaler
   411     Simplifier.add_context_looper
   412     Simplifier.del_context_looper
   413     Simplifier.add_context_unsafe_solver
   414     Simplifier.add_context_safe_solver
   415 
   416     Classical.add_context_safe_wrapper
   417     Classical.del_context_safe_wrapper
   418     Classical.add_context_unsafe_wrapper
   419     Classical.del_context_unsafe_wrapper
   420 
   421   IMPORTANT NOTE: proof tools (methods etc.) need to use
   422   local_simpset_of and local_claset_of to instead of the primitive
   423   Simplifier.get_local_simpset and Classical.get_local_claset,
   424   respectively, in order to see the context dependent fields!
   425 
   426 
   427 
   428 New in Isabelle2004 (April 2004)
   429 --------------------------------
   430 
   431 *** General ***
   432 
   433 * Provers/order.ML:  new efficient reasoner for partial and linear orders.
   434   Replaces linorder.ML.
   435 
   436 * Pure: Greek letters (except small lambda, \<lambda>), as well as Gothic
   437   (\<aa>...\<zz>\<AA>...\<ZZ>), calligraphic (\<A>...\<Z>), and Euler
   438   (\<a>...\<z>), are now considered normal letters, and can therefore
   439   be used anywhere where an ASCII letter (a...zA...Z) has until
   440   now. COMPATIBILITY: This obviously changes the parsing of some
   441   terms, especially where a symbol has been used as a binder, say
   442   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed
   443   as an identifier.  Fix it by inserting a space around former
   444   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in
   445   existing theory and ML files.
   446 
   447 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.
   448 
   449 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now
   450   allowed in identifiers. Similar to Greek letters \<^isub> is now considered
   451   a normal (but invisible) letter. For multiple letter subscripts repeat
   452   \<^isub> like this: x\<^isub>1\<^isub>2.
   453 
   454 * Pure: There are now sub-/superscripts that can span more than one
   455   character. Text between \<^bsub> and \<^esub> is set in subscript in
   456   ProofGeneral and LaTeX, text between \<^bsup> and \<^esup> in
   457   superscript. The new control characters are not identifier parts.
   458 
   459 * Pure: Control-symbols of the form \<^raw:...> will literally print the
   460   content of "..." to the latex file instead of \isacntrl... . The "..."
   461   may consist of any printable characters excluding the end bracket >.
   462 
   463 * Pure: Using new Isar command "finalconsts" (or the ML functions
   464   Theory.add_finals or Theory.add_finals_i) it is now possible to
   465   declare constants "final", which prevents their being given a definition
   466   later.  It is useful for constants whose behaviour is fixed axiomatically
   467   rather than definitionally, such as the meta-logic connectives.
   468 
   469 * Pure: 'instance' now handles general arities with general sorts
   470   (i.e. intersections of classes),
   471 
   472 * Presentation: generated HTML now uses a CSS style sheet to make layout
   473   (somewhat) independent of content. It is copied from lib/html/isabelle.css.
   474   It can be changed to alter the colors/layout of generated pages.
   475 
   476 
   477 *** Isar ***
   478 
   479 * Tactic emulation methods rule_tac, erule_tac, drule_tac, frule_tac,
   480   cut_tac, subgoal_tac and thin_tac:
   481   - Now understand static (Isar) contexts.  As a consequence, users of Isar
   482     locales are no longer forced to write Isar proof scripts.
   483     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
   484     emulations.
   485   - INCOMPATIBILITY: names of variables to be instantiated may no
   486     longer be enclosed in quotes.  Instead, precede variable name with `?'.
   487     This is consistent with the instantiation attribute "where".
   488 
   489 * Attributes "where" and "of":
   490   - Now take type variables of instantiated theorem into account when reading
   491     the instantiation string.  This fixes a bug that caused instantiated
   492     theorems to have too special types in some circumstances.
   493   - "where" permits explicit instantiations of type variables.
   494 
   495 * Calculation commands "moreover" and "also" no longer interfere with
   496   current facts ("this"), admitting arbitrary combinations with "then"
   497   and derived forms.
   498 
   499 * Locales:
   500   - Goal statements involving the context element "includes" no longer
   501     generate theorems with internal delta predicates (those ending on
   502     "_axioms") in the premise.
   503     Resolve particular premise with <locale>.intro to obtain old form.
   504   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
   505     specification and "includes" elements in goal statement.
   506   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
   507     [intro?] and [elim?] (respectively) by default.
   508   - Experimental command for instantiation of locales in proof contexts:
   509         instantiate <label>[<attrs>]: <loc>
   510     Instantiates locale <loc> and adds all its theorems to the current context
   511     taking into account their attributes.  Label and attrs are optional
   512     modifiers, like in theorem declarations.  If present, names of
   513     instantiated theorems are qualified with <label>, and the attributes
   514     <attrs> are applied after any attributes these theorems might have already.
   515       If the locale has assumptions, a chained fact of the form
   516     "<loc> t1 ... tn" is expected from which instantiations of the parameters
   517     are derived.  The command does not support old-style locales declared
   518     with "locale (open)".
   519       A few (very simple) examples can be found in FOL/ex/LocaleInst.thy.
   520 
   521 * HOL: Tactic emulation methods induct_tac and case_tac understand static
   522   (Isar) contexts.
   523 
   524 
   525 *** HOL ***
   526 
   527 * Proof import: new image HOL4 contains the imported library from
   528   the HOL4 system with about 2500 theorems. It is imported by
   529   replaying proof terms produced by HOL4 in Isabelle. The HOL4 image
   530   can be used like any other Isabelle image.  See
   531   HOL/Import/HOL/README for more information.
   532 
   533 * Simplifier:
   534   - Much improved handling of linear and partial orders.
   535     Reasoners for linear and partial orders are set up for type classes
   536     "linorder" and "order" respectively, and are added to the default simpset
   537     as solvers.  This means that the simplifier can build transitivity chains
   538     to solve goals from the assumptions.
   539   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications
   540     of blast or auto after simplification become unnecessary because the goal
   541     is solved by simplification already.
   542 
   543 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws,
   544     all proved in axiomatic type classes for semirings, rings and fields.
   545 
   546 * Numerics:
   547   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are
   548     now formalized using the Ring_and_Field theory mentioned above.
   549   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently
   550     than before, because now they are set up once in a generic manner.
   551   - INCOMPATIBILITY: many type-specific arithmetic laws have gone.
   552     Look for the general versions in Ring_and_Field (and Power if they concern
   553     exponentiation).
   554 
   555 * Type "rat" of the rational numbers is now available in HOL-Complex.
   556 
   557 * Records:
   558   - Record types are now by default printed with their type abbreviation
   559     instead of the list of all field types. This can be configured via
   560     the reference "print_record_type_abbr".
   561   - Simproc "record_upd_simproc" for simplification of multiple updates added
   562     (not enabled by default).
   563   - Simproc "record_ex_sel_eq_simproc" to simplify EX x. sel r = x resp.
   564     EX x. x = sel r to True (not enabled by default).
   565   - Tactic "record_split_simp_tac" to split and simplify records added.
   566 
   567 * 'specification' command added, allowing for definition by
   568   specification.  There is also an 'ax_specification' command that
   569   introduces the new constants axiomatically.
   570 
   571 * arith(_tac) is now able to generate counterexamples for reals as well.
   572 
   573 * HOL-Algebra: new locale "ring" for non-commutative rings.
   574 
   575 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
   576   definitions, thanks to Sava Krsti\'{c} and John Matthews.
   577 
   578 * HOL-Matrix: a first theory for matrices in HOL with an application of
   579   matrix theory to linear programming.
   580 
   581 * Unions and Intersections:
   582   The latex output syntax of UN and INT has been changed
   583   from "\Union x \in A. B" to "\Union_{x \in A} B"
   584   i.e. the index formulae has become a subscript.
   585   Similarly for "\Union x. B", and for \Inter instead of \Union.
   586 
   587 * Unions and Intersections over Intervals:
   588   There is new short syntax "UN i<=n. A" for "UN i:{0..n}. A". There is
   589   also an x-symbol version with subscripts "\<Union>\<^bsub>i <= n\<^esub>. A"
   590   like in normal math, and corresponding versions for < and for intersection.
   591 
   592 * HOL/List: Ordering "lexico" is renamed "lenlex" and the standard
   593   lexicographic dictonary ordering has been added as "lexord".
   594 
   595 * ML: the legacy theory structures Int and List have been removed. They had
   596   conflicted with ML Basis Library structures having the same names.
   597 
   598 * 'refute' command added to search for (finite) countermodels.  Only works
   599   for a fragment of HOL.  The installation of an external SAT solver is
   600   highly recommended.  See "HOL/Refute.thy" for details.
   601 
   602 * 'quickcheck' command: Allows to find counterexamples by evaluating
   603   formulae under an assignment of free variables to random values.
   604   In contrast to 'refute', it can deal with inductive datatypes,
   605   but cannot handle quantifiers. See "HOL/ex/Quickcheck_Examples.thy"
   606   for examples.
   607 
   608 
   609 *** HOLCF ***
   610 
   611 * Streams now come with concatenation and are part of the HOLCF image
   612 
   613 
   614 
   615 New in Isabelle2003 (May 2003)
   616 ------------------------------
   617 
   618 *** General ***
   619 
   620 * Provers/simplifier:
   621 
   622   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   623     Assumptions are now subject to complete mutual simplification,
   624     not just from left to right. The simplifier now preserves
   625     the order of assumptions.
   626 
   627     Potential INCOMPATIBILITY:
   628 
   629     -- simp sometimes diverges where the old version did
   630        not, e.g. invoking simp on the goal
   631 
   632         [| P (f x); y = x; f x = f y |] ==> Q
   633 
   634        now gives rise to the infinite reduction sequence
   635 
   636         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   637 
   638        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   639        kind of problem.
   640 
   641     -- Tactics combining classical reasoner and simplification (such as auto)
   642        are also affected by this change, because many of them rely on
   643        simp. They may sometimes diverge as well or yield a different numbers
   644        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   645        in case of problems. Sometimes subsequent calls to the classical
   646        reasoner will fail because a preceeding call to the simplifier too
   647        eagerly simplified the goal, e.g. deleted redundant premises.
   648 
   649   - The simplifier trace now shows the names of the applied rewrite rules
   650 
   651   - You can limit the number of recursive invocations of the simplifier
   652     during conditional rewriting (where the simplifie tries to solve the
   653     conditions before applying the rewrite rule):
   654     ML "simp_depth_limit := n"
   655     where n is an integer. Thus you can force termination where previously
   656     the simplifier would diverge.
   657 
   658   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   659 
   660   - No longer aborts on failed congruence proof.  Instead, the
   661     congruence is ignored.
   662 
   663 * Pure: New generic framework for extracting programs from constructive
   664   proofs. See HOL/Extraction.thy for an example instantiation, as well
   665   as HOL/Extraction for some case studies.
   666 
   667 * Pure: The main goal of the proof state is no longer shown by default, only
   668 the subgoals. This behaviour is controlled by a new flag.
   669    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   670 (ML: Proof.show_main_goal).
   671 
   672 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   673 rules whose conclusion matches subgoal 1:
   674       PG menu: Isabelle/Isar -> Show me -> matching rules
   675 The rules are ordered by how closely they match the subgoal.
   676 In particular, rules that solve a subgoal outright are displayed first
   677 (or rather last, the way they are printed).
   678 (ML: ProofGeneral.print_intros())
   679 
   680 * Pure: New flag trace_unify_fail causes unification to print
   681 diagnostic information (PG: in trace buffer) when it fails. This is
   682 useful for figuring out why single step proofs like rule, erule or
   683 assumption failed.
   684 
   685 * Pure: Locale specifications now produce predicate definitions
   686 according to the body of text (covering assumptions modulo local
   687 definitions); predicate "loc_axioms" covers newly introduced text,
   688 while "loc" is cumulative wrt. all included locale expressions; the
   689 latter view is presented only on export into the global theory
   690 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   691 on the old view without predicates;
   692 
   693 * Pure: predefined locales "var" and "struct" are useful for sharing
   694 parameters (as in CASL, for example); just specify something like
   695 ``var x + var y + struct M'' as import;
   696 
   697 * Pure: improved thms_containing: proper indexing of facts instead of
   698 raw theorems; check validity of results wrt. current name space;
   699 include local facts of proof configuration (also covers active
   700 locales), cover fixed variables in index; may use "_" in term
   701 specification; an optional limit for the number of printed facts may
   702 be given (the default is 40);
   703 
   704 * Pure: disallow duplicate fact bindings within new-style theory files
   705 (batch-mode only);
   706 
   707 * Provers: improved induct method: assumptions introduced by case
   708 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   709 the goal statement); "foo" still refers to all facts collectively;
   710 
   711 * Provers: the function blast.overloaded has been removed: all constants
   712 are regarded as potentially overloaded, which improves robustness in exchange
   713 for slight decrease in efficiency;
   714 
   715 * Provers/linorder: New generic prover for transitivity reasoning over
   716 linear orders.  Note: this prover is not efficient!
   717 
   718 * Isar: preview of problems to finish 'show' now produce an error
   719 rather than just a warning (in interactive mode);
   720 
   721 
   722 *** HOL ***
   723 
   724 * arith(_tac)
   725 
   726  - Produces a counter example if it cannot prove a goal.
   727    Note that the counter example may be spurious if the goal is not a formula
   728    of quantifier-free linear arithmetic.
   729    In ProofGeneral the counter example appears in the trace buffer.
   730 
   731  - Knows about div k and mod k where k is a numeral of type nat or int.
   732 
   733  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   734    linear arithmetic fails. This takes account of quantifiers and divisibility.
   735    Presburger arithmetic can also be called explicitly via presburger(_tac).
   736 
   737 * simp's arithmetic capabilities have been enhanced a bit: it now
   738 takes ~= in premises into account (by performing a case split);
   739 
   740 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   741 are distributed over a sum of terms;
   742 
   743 * New tactic "trans_tac" and method "trans" instantiate
   744 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   745 "<=", "<" and "=").
   746 
   747 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main
   748 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   749 
   750 * 'typedef' command has new option "open" to suppress the set
   751 definition;
   752 
   753 * functions Min and Max on finite sets have been introduced (theory
   754 Finite_Set);
   755 
   756 * attribute [symmetric] now works for relations as well; it turns
   757 (x,y) : R^-1 into (y,x) : R, and vice versa;
   758 
   759 * induct over a !!-quantified statement (say !!x1..xn):
   760   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   761 
   762 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   763 %x. None. Warning: empty_def now refers to the previously hidden definition
   764 of the empty set.
   765 
   766 * Algebra: formalization of classical algebra.  Intended as base for
   767 any algebraic development in Isabelle.  Currently covers group theory
   768 (up to Sylow's theorem) and ring theory (Universal Property of
   769 Univariate Polynomials).  Contributions welcome;
   770 
   771 * GroupTheory: deleted, since its material has been moved to Algebra;
   772 
   773 * Complex: new directory of the complex numbers with numeric constants,
   774 nonstandard complex numbers, and some complex analysis, standard and
   775 nonstandard (Jacques Fleuriot);
   776 
   777 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   778 
   779 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques
   780 Fleuriot);
   781 
   782 * Real/HahnBanach: updated and adapted to locales;
   783 
   784 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   785 Gray and Kramer);
   786 
   787 * UNITY: added the Meier-Sanders theory of progress sets;
   788 
   789 * MicroJava: bytecode verifier and lightweight bytecode verifier
   790 as abstract algorithms, instantiated to the JVM;
   791 
   792 * Bali: Java source language formalization. Type system, operational
   793 semantics, axiomatic semantics. Supported language features:
   794 classes, interfaces, objects,virtual methods, static methods,
   795 static/instance fields, arrays, access modifiers, definite
   796 assignment, exceptions.
   797 
   798 
   799 *** ZF ***
   800 
   801 * ZF/Constructible: consistency proof for AC (Gdel's constructible
   802 universe, etc.);
   803 
   804 * Main ZF: virtually all theories converted to new-style format;
   805 
   806 
   807 *** ML ***
   808 
   809 * Pure: Tactic.prove provides sane interface for internal proofs;
   810 omits the infamous "standard" operation, so this is more appropriate
   811 than prove_goalw_cterm in many situations (e.g. in simprocs);
   812 
   813 * Pure: improved error reporting of simprocs;
   814 
   815 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   816 up simprocs;
   817 
   818 
   819 *** Document preparation ***
   820 
   821 * uses \par instead of \\ for line breaks in theory text. This may
   822 shift some page breaks in large documents. To get the old behaviour
   823 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   824 
   825 * minimized dependencies of isabelle.sty and isabellesym.sty on
   826 other packages
   827 
   828 * \<euro> now needs package babel/greek instead of marvosym (which
   829 broke \Rightarrow)
   830 
   831 * normal size for \<zero>...\<nine> (uses \mathbf instead of
   832 textcomp package)
   833 
   834 
   835 
   836 New in Isabelle2002 (March 2002)
   837 --------------------------------
   838 
   839 *** Document preparation ***
   840 
   841 * greatly simplified document preparation setup, including more
   842 graceful interpretation of isatool usedir -i/-d/-D options, and more
   843 instructive isatool mkdir; users should basically be able to get
   844 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   845 users may run a separate document processing stage manually like this:
   846 "isatool usedir -D output HOL Test && isatool document Test/output";
   847 
   848 * theory dependency graph may now be incorporated into documents;
   849 isatool usedir -g true will produce session_graph.eps/.pdf for use
   850 with \includegraphics of LaTeX;
   851 
   852 * proper spacing of consecutive markup elements, especially text
   853 blocks after section headings;
   854 
   855 * support bold style (for single symbols only), input syntax is like
   856 this: "\<^bold>\<alpha>" or "\<^bold>A";
   857 
   858 * \<bullet> is now output as bold \cdot by default, which looks much
   859 better in printed text;
   860 
   861 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   862 note that these symbols are currently unavailable in Proof General /
   863 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   864 
   865 * isatool latex no longer depends on changed TEXINPUTS, instead
   866 isatool document copies the Isabelle style files to the target
   867 location;
   868 
   869 
   870 *** Isar ***
   871 
   872 * Pure/Provers: improved proof by cases and induction;
   873   - 'case' command admits impromptu naming of parameters (such as
   874     "case (Suc n)");
   875   - 'induct' method divinates rule instantiation from the inductive
   876     claim; no longer requires excessive ?P bindings for proper
   877     instantiation of cases;
   878   - 'induct' method properly enumerates all possibilities of set/type
   879     rules; as a consequence facts may be also passed through *type*
   880     rules without further ado;
   881   - 'induct' method now derives symbolic cases from the *rulified*
   882     rule (before it used to rulify cases stemming from the internal
   883     atomized version); this means that the context of a non-atomic
   884     statement becomes is included in the hypothesis, avoiding the
   885     slightly cumbersome show "PROP ?case" form;
   886   - 'induct' may now use elim-style induction rules without chaining
   887     facts, using ``missing'' premises from the goal state; this allows
   888     rules stemming from inductive sets to be applied in unstructured
   889     scripts, while still benefitting from proper handling of non-atomic
   890     statements; NB: major inductive premises need to be put first, all
   891     the rest of the goal is passed through the induction;
   892   - 'induct' proper support for mutual induction involving non-atomic
   893     rule statements (uses the new concept of simultaneous goals, see
   894     below);
   895   - append all possible rule selections, but only use the first
   896     success (no backtracking);
   897   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   898   - undeclared rule case names default to numbers 1, 2, 3, ...;
   899   - added 'print_induct_rules' (covered by help item in recent Proof
   900     General versions);
   901   - moved induct/cases attributes to Pure, methods to Provers;
   902   - generic method setup instantiated for FOL and HOL;
   903 
   904 * Pure: support multiple simultaneous goal statements, for example
   905 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   906 meta-level mechanism, this acts as if several individual goals had
   907 been stated separately; in particular common proof methods need to be
   908 repeated in order to cover all claims; note that a single elimination
   909 step is *not* sufficient to establish the two conjunctions, so this
   910 fails:
   911 
   912   assume "A & B" then have A and B ..   (*".." fails*)
   913 
   914 better use "obtain" in situations as above; alternative refer to
   915 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   916 
   917 * Pure: proper integration with ``locales''; unlike the original
   918 version by Florian Kammller, Isar locales package high-level proof
   919 contexts rather than raw logical ones (e.g. we admit to include
   920 attributes everywhere); operations on locales include merge and
   921 rename; support for implicit arguments (``structures''); simultaneous
   922 type-inference over imports and text; see also HOL/ex/Locales.thy for
   923 some examples;
   924 
   925 * Pure: the following commands have been ``localized'', supporting a
   926 target locale specification "(in name)": 'lemma', 'theorem',
   927 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   928 stored both within the locale and at the theory level (exported and
   929 qualified by the locale name);
   930 
   931 * Pure: theory goals may now be specified in ``long'' form, with
   932 ad-hoc contexts consisting of arbitrary locale elements. for example
   933 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   934 definitions may be given, too); the result is a meta-level rule with
   935 the context elements being discharged in the obvious way;
   936 
   937 * Pure: new proof command 'using' allows to augment currently used
   938 facts after a goal statement ('using' is syntactically analogous to
   939 'apply', but acts on the goal's facts only); this allows chained facts
   940 to be separated into parts given before and after a claim, as in
   941 ``from a and b have C using d and e <proof>'';
   942 
   943 * Pure: renamed "antecedent" case to "rule_context";
   944 
   945 * Pure: new 'judgment' command records explicit information about the
   946 object-logic embedding (used by several tools internally); no longer
   947 use hard-wired "Trueprop";
   948 
   949 * Pure: added 'corollary' command;
   950 
   951 * Pure: fixed 'token_translation' command;
   952 
   953 * Pure: removed obsolete 'exported' attribute;
   954 
   955 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   956 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   957 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   958 
   959 * Pure: method 'atomize' presents local goal premises as object-level
   960 statements (atomic meta-level propositions); setup controlled via
   961 rewrite rules declarations of 'atomize' attribute; example
   962 application: 'induct' method with proper rule statements in improper
   963 proof *scripts*;
   964 
   965 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   966 now consider the syntactic context of assumptions, giving a better
   967 chance to get type-inference of the arguments right (this is
   968 especially important for locales);
   969 
   970 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   971 mode;
   972 
   973 * Pure/obtain: the formal conclusion "thesis", being marked as
   974 ``internal'', may no longer be reference directly in the text;
   975 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   976 situations;
   977 
   978 * Pure: generic 'sym' attribute which declares a rule both as pure
   979 'elim?' and for the 'symmetric' operation;
   980 
   981 * Pure: marginal comments ``--'' may now occur just anywhere in the
   982 text; the fixed correlation with particular command syntax has been
   983 discontinued;
   984 
   985 * Pure: new method 'rules' is particularly well-suited for proof
   986 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   987 but often produces more compact proof terms with less detours;
   988 
   989 * Pure/Provers/classical: simplified integration with pure rule
   990 attributes and methods; the classical "intro?/elim?/dest?"
   991 declarations coincide with the pure ones; the "rule" method no longer
   992 includes classically swapped intros; "intro" and "elim" methods no
   993 longer pick rules from the context; also got rid of ML declarations
   994 AddXIs/AddXEs/AddXDs; all of this has some potential for
   995 INCOMPATIBILITY;
   996 
   997 * Provers/classical: attribute 'swapped' produces classical inversions
   998 of introduction rules;
   999 
  1000 * Provers/simplifier: 'simplified' attribute may refer to explicit
  1001 rules instead of full simplifier context; 'iff' attribute handles
  1002 conditional rules;
  1003 
  1004 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
  1005 
  1006 * HOL: 'recdef' now fails on unfinished automated proofs, use
  1007 "(permissive)" option to recover old behavior;
  1008 
  1009 * HOL: 'inductive' no longer features separate (collective) attributes
  1010 for 'intros' (was found too confusing);
  1011 
  1012 * HOL: properly declared induction rules less_induct and
  1013 wf_induct_rule;
  1014 
  1015 
  1016 *** HOL ***
  1017 
  1018 * HOL: moved over to sane numeral syntax; the new policy is as
  1019 follows:
  1020 
  1021   - 0 and 1 are polymorphic constants, which are defined on any
  1022   numeric type (nat, int, real etc.);
  1023 
  1024   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
  1025   binary representation internally;
  1026 
  1027   - type nat has special constructor Suc, and generally prefers Suc 0
  1028   over 1::nat and Suc (Suc 0) over 2::nat;
  1029 
  1030 This change may cause significant problems of INCOMPATIBILITY; here
  1031 are some hints on converting existing sources:
  1032 
  1033   - due to the new "num" token, "-0" and "-1" etc. are now atomic
  1034   entities, so expressions involving "-" (unary or binary minus) need
  1035   to be spaced properly;
  1036 
  1037   - existing occurrences of "1" may need to be constraint "1::nat" or
  1038   even replaced by Suc 0; similar for old "2";
  1039 
  1040   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
  1041 
  1042   - remove all special provisions on numerals in proofs;
  1043 
  1044 * HOL: simp rules nat_number expand numerals on nat to Suc/0
  1045 representation (depends on bin_arith_simps in the default context);
  1046 
  1047 * HOL: symbolic syntax for x^2 (numeral 2);
  1048 
  1049 * HOL: the class of all HOL types is now called "type" rather than
  1050 "term"; INCOMPATIBILITY, need to adapt references to this type class
  1051 in axclass/classes, instance/arities, and (usually rare) occurrences
  1052 in typings (of consts etc.); internally the class is called
  1053 "HOL.type", ML programs should refer to HOLogic.typeS;
  1054 
  1055 * HOL/record package improvements:
  1056   - new derived operations "fields" to build a partial record section,
  1057     "extend" to promote a fixed record to a record scheme, and
  1058     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
  1059     declared as simp by default;
  1060   - shared operations ("more", "fields", etc.) now need to be always
  1061     qualified) --- potential INCOMPATIBILITY;
  1062   - removed "make_scheme" operations (use "make" with "extend") --
  1063     INCOMPATIBILITY;
  1064   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
  1065   - provides cases/induct rules for use with corresponding Isar
  1066     methods (for concrete records, record schemes, concrete more
  1067     parts, and schematic more parts -- in that order);
  1068   - internal definitions directly based on a light-weight abstract
  1069     theory of product types over typedef rather than datatype;
  1070 
  1071 * HOL: generic code generator for generating executable ML code from
  1072 specifications; specific support for HOL constructs such as inductive
  1073 datatypes and sets, as well as recursive functions; can be invoked
  1074 via 'generate_code' theory section;
  1075 
  1076 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
  1077 
  1078 * HOL: consolidated and renamed several theories.  In particular:
  1079         Ord.thy has been absorbed into HOL.thy
  1080         String.thy has been absorbed into List.thy
  1081 
  1082 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
  1083 (beware of argument permutation!);
  1084 
  1085 * HOL: linorder_less_split superseded by linorder_cases;
  1086 
  1087 * HOL/List: "nodups" renamed to "distinct";
  1088 
  1089 * HOL: added "The" definite description operator; move Hilbert's "Eps"
  1090 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
  1091   - Ex_def has changed, now need to use some_eq_ex
  1092 
  1093 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
  1094 in this (rare) case use:
  1095 
  1096   delSWrapper "split_all_tac"
  1097   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
  1098 
  1099 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
  1100 MAY FAIL;
  1101 
  1102 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
  1103 Isabelle's type classes, ^ on functions and relations has too general
  1104 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
  1105 necessary to attach explicit type constraints;
  1106 
  1107 * HOL/Relation: the prefix name of the infix "O" has been changed from
  1108 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
  1109 renamed accordingly (eg "compI" -> "rel_compI").
  1110 
  1111 * HOL: syntax translations now work properly with numerals and records
  1112 expressions;
  1113 
  1114 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
  1115 of "lam" -- INCOMPATIBILITY;
  1116 
  1117 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
  1118 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
  1119 renamed "Product_Type.unit";
  1120 
  1121 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
  1122 
  1123 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
  1124 the "cases" method);
  1125 
  1126 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
  1127 Florian Kammller);
  1128 
  1129 * HOL/IMP: updated and converted to new-style theory format; several
  1130 parts turned into readable document, with proper Isar proof texts and
  1131 some explanations (by Gerwin Klein);
  1132 
  1133 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
  1134 
  1135 * HOL-Hyperreal is now a logic image;
  1136 
  1137 
  1138 *** HOLCF ***
  1139 
  1140 * Isar: consts/constdefs supports mixfix syntax for continuous
  1141 operations;
  1142 
  1143 * Isar: domain package adapted to new-style theory format, e.g. see
  1144 HOLCF/ex/Dnat.thy;
  1145 
  1146 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
  1147 potential INCOMPATIBILITY; now use plain induct_tac instead of former
  1148 lift.induct_tac, always use UU instead of Undef;
  1149 
  1150 * HOLCF/IMP: updated and converted to new-style theory;
  1151 
  1152 
  1153 *** ZF ***
  1154 
  1155 * Isar: proper integration of logic-specific tools and packages,
  1156 including theory commands '(co)inductive', '(co)datatype',
  1157 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
  1158 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
  1159 
  1160 * theory Main no longer includes AC; for the Axiom of Choice, base
  1161 your theory on Main_ZFC;
  1162 
  1163 * the integer library now covers quotients and remainders, with many
  1164 laws relating division to addition, multiplication, etc.;
  1165 
  1166 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
  1167 typeless version of the formalism;
  1168 
  1169 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
  1170 format;
  1171 
  1172 * ZF/Induct: new directory for examples of inductive definitions,
  1173 including theory Multiset for multiset orderings; converted to
  1174 new-style theory format;
  1175 
  1176 * ZF: many new theorems about lists, ordinals, etc.;
  1177 
  1178 
  1179 *** General ***
  1180 
  1181 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
  1182 variable proof controls level of detail: 0 = no proofs (only oracle
  1183 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
  1184 also ref manual for further ML interfaces;
  1185 
  1186 * Pure/axclass: removed obsolete ML interface
  1187 goal_subclass/goal_arity;
  1188 
  1189 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
  1190 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
  1191 separate tokens, so expressions involving minus need to be spaced
  1192 properly;
  1193 
  1194 * Pure/syntax: support non-oriented infixes, using keyword "infix"
  1195 rather than "infixl" or "infixr";
  1196 
  1197 * Pure/syntax: concrete syntax for dummy type variables admits genuine
  1198 sort constraint specifications in type inference; e.g. "x::_::foo"
  1199 ensures that the type of "x" is of sort "foo" (but not necessarily a
  1200 type variable);
  1201 
  1202 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
  1203 control output of nested => (types); the default behavior is
  1204 "type_brackets";
  1205 
  1206 * Pure/syntax: builtin parse translation for "_constify" turns valued
  1207 tokens into AST constants;
  1208 
  1209 * Pure/syntax: prefer later declarations of translations and print
  1210 translation functions; potential INCOMPATIBILITY: need to reverse
  1211 multiple declarations for same syntax element constant;
  1212 
  1213 * Pure/show_hyps reset by default (in accordance to existing Isar
  1214 practice);
  1215 
  1216 * Provers/classical: renamed addaltern to addafter, addSaltern to
  1217 addSafter;
  1218 
  1219 * Provers/clasimp: ``iff'' declarations now handle conditional rules
  1220 as well;
  1221 
  1222 * system: tested support for MacOS X; should be able to get Isabelle +
  1223 Proof General to work in a plain Terminal after installing Poly/ML
  1224 (e.g. from the Isabelle distribution area) and GNU bash alone
  1225 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
  1226 support requires further installations, e.g. from
  1227 http://fink.sourceforge.net/);
  1228 
  1229 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
  1230 
  1231 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
  1232 of 40 MB), cf. ML_OPTIONS;
  1233 
  1234 * system: Proof General keywords specification is now part of the
  1235 Isabelle distribution (see etc/isar-keywords.el);
  1236 
  1237 * system: support for persistent Proof General sessions (refrain from
  1238 outdating all loaded theories on startup); user may create writable
  1239 logic images like this: ``isabelle -q HOL Test'';
  1240 
  1241 * system: smart selection of Isabelle process versus Isabelle
  1242 interface, accommodates case-insensitive file systems (e.g. HFS+); may
  1243 run both "isabelle" and "Isabelle" even if file names are badly
  1244 damaged (executable inspects the case of the first letter of its own
  1245 name); added separate "isabelle-process" and "isabelle-interface";
  1246 
  1247 * system: refrain from any attempt at filtering input streams; no
  1248 longer support ``8bit'' encoding of old isabelle font, instead proper
  1249 iso-latin characters may now be used; the related isatools
  1250 "symbolinput" and "nonascii" have disappeared as well;
  1251 
  1252 * system: removed old "xterm" interface (the print modes "xterm" and
  1253 "xterm_color" are still available for direct use in a suitable
  1254 terminal);
  1255 
  1256 
  1257 
  1258 New in Isabelle99-2 (February 2001)
  1259 -----------------------------------
  1260 
  1261 *** Overview of INCOMPATIBILITIES ***
  1262 
  1263 * HOL: please note that theories in the Library and elsewhere often use the
  1264 new-style (Isar) format; to refer to their theorems in an ML script you must
  1265 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
  1266 
  1267 * HOL: inductive package no longer splits induction rule aggressively,
  1268 but only as far as specified by the introductions given; the old
  1269 format may be recovered via ML function complete_split_rule or attribute
  1270 'split_rule (complete)';
  1271 
  1272 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
  1273 gfp_Tarski to gfp_unfold;
  1274 
  1275 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
  1276 
  1277 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
  1278 relation); infix "^^" has been renamed "``"; infix "``" has been
  1279 renamed "`"; "univalent" has been renamed "single_valued";
  1280 
  1281 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
  1282 operation;
  1283 
  1284 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
  1285 
  1286 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
  1287 
  1288 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
  1289 consequence, it is no longer monotonic wrt. the local goal context
  1290 (which is now passed through the inductive cases);
  1291 
  1292 * Document preparation: renamed standard symbols \<ll> to \<lless> and
  1293 \<gg> to \<ggreater>;
  1294 
  1295 
  1296 *** Document preparation ***
  1297 
  1298 * \isabellestyle{NAME} selects version of Isabelle output (currently
  1299 available: are "it" for near math-mode best-style output, "sl" for
  1300 slanted text style, and "tt" for plain type-writer; if no
  1301 \isabellestyle command is given, output is according to slanted
  1302 type-writer);
  1303 
  1304 * support sub/super scripts (for single symbols only), input syntax is
  1305 like this: "A\<^sup>*" or "A\<^sup>\<star>";
  1306 
  1307 * some more standard symbols; see Appendix A of the system manual for
  1308 the complete list of symbols defined in isabellesym.sty;
  1309 
  1310 * improved isabelle style files; more abstract symbol implementation
  1311 (should now use \isamath{...} and \isatext{...} in custom symbol
  1312 definitions);
  1313 
  1314 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
  1315 state; Note that presentation of goal states does not conform to
  1316 actual human-readable proof documents.  Please do not include goal
  1317 states into document output unless you really know what you are doing!
  1318 
  1319 * proper indentation of antiquoted output with proportional LaTeX
  1320 fonts;
  1321 
  1322 * no_document ML operator temporarily disables LaTeX document
  1323 generation;
  1324 
  1325 * isatool unsymbolize tunes sources for plain ASCII communication;
  1326 
  1327 
  1328 *** Isar ***
  1329 
  1330 * Pure: Isar now suffers initial goal statements to contain unbound
  1331 schematic variables (this does not conform to actual readable proof
  1332 documents, due to unpredictable outcome and non-compositional proof
  1333 checking); users who know what they are doing may use schematic goals
  1334 for Prolog-style synthesis of proven results;
  1335 
  1336 * Pure: assumption method (an implicit finishing) now handles actual
  1337 rules as well;
  1338 
  1339 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
  1340 initial goal, declare "that" only as Pure intro (only for single
  1341 steps); the "that" rule assumption may now be involved in implicit
  1342 finishing, thus ".." becomes a feasible for trivial obtains;
  1343 
  1344 * Pure: default proof step now includes 'intro_classes'; thus trivial
  1345 instance proofs may be performed by "..";
  1346 
  1347 * Pure: ?thesis / ?this / "..." now work for pure meta-level
  1348 statements as well;
  1349 
  1350 * Pure: more robust selection of calculational rules;
  1351 
  1352 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
  1353 rule (as well as the assumption rule);
  1354 
  1355 * Pure: 'thm_deps' command visualizes dependencies of theorems and
  1356 lemmas, using the graph browser tool;
  1357 
  1358 * Pure: predict failure of "show" in interactive mode;
  1359 
  1360 * Pure: 'thms_containing' now takes actual terms as arguments;
  1361 
  1362 * HOL: improved method 'induct' --- now handles non-atomic goals
  1363 (potential INCOMPATIBILITY); tuned error handling;
  1364 
  1365 * HOL: cases and induct rules now provide explicit hints about the
  1366 number of facts to be consumed (0 for "type" and 1 for "set" rules);
  1367 any remaining facts are inserted into the goal verbatim;
  1368 
  1369 * HOL: local contexts (aka cases) may now contain term bindings as
  1370 well; the 'cases' and 'induct' methods new provide a ?case binding for
  1371 the result to be shown in each case;
  1372 
  1373 * HOL: added 'recdef_tc' command;
  1374 
  1375 * isatool convert assists in eliminating legacy ML scripts;
  1376 
  1377 
  1378 *** HOL ***
  1379 
  1380 * HOL/Library: a collection of generic theories to be used together
  1381 with main HOL; the theory loader path already includes this directory
  1382 by default; the following existing theories have been moved here:
  1383 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
  1384 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
  1385 
  1386 * HOL/Unix: "Some aspects of Unix file-system security", a typical
  1387 modelling and verification task performed in Isabelle/HOL +
  1388 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
  1389 
  1390 * HOL/Algebra: special summation operator SUM no longer exists, it has
  1391 been replaced by setsum; infix 'assoc' now has priority 50 (like
  1392 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
  1393 'domain', this makes the theory consistent with mathematical
  1394 literature;
  1395 
  1396 * HOL basics: added overloaded operations "inverse" and "divide"
  1397 (infix "/"), syntax for generic "abs" operation, generic summation
  1398 operator \<Sum>;
  1399 
  1400 * HOL/typedef: simplified package, provide more useful rules (see also
  1401 HOL/subset.thy);
  1402 
  1403 * HOL/datatype: induction rule for arbitrarily branching datatypes is
  1404 now expressed as a proper nested rule (old-style tactic scripts may
  1405 require atomize_strip_tac to cope with non-atomic premises);
  1406 
  1407 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
  1408 to "split_conv" (old name still available for compatibility);
  1409 
  1410 * HOL: improved concrete syntax for strings (e.g. allows translation
  1411 rules with string literals);
  1412 
  1413 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
  1414  and Fleuriot's mechanization of analysis, including the transcendental
  1415  functions for the reals;
  1416 
  1417 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
  1418 
  1419 
  1420 *** CTT ***
  1421 
  1422 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
  1423 "lam" is displayed as TWO lambda-symbols
  1424 
  1425 * CTT: theory Main now available, containing everything (that is, Bool
  1426 and Arith);
  1427 
  1428 
  1429 *** General ***
  1430 
  1431 * Pure: the Simplifier has been implemented properly as a derived rule
  1432 outside of the actual kernel (at last!); the overall performance
  1433 penalty in practical applications is about 50%, while reliability of
  1434 the Isabelle inference kernel has been greatly improved;
  1435 
  1436 * print modes "brackets" and "no_brackets" control output of nested =>
  1437 (types) and ==> (props); the default behaviour is "brackets";
  1438 
  1439 * Provers: fast_tac (and friends) now handle actual object-logic rules
  1440 as assumptions as well;
  1441 
  1442 * system: support Poly/ML 4.0;
  1443 
  1444 * system: isatool install handles KDE version 1 or 2;
  1445 
  1446 
  1447 
  1448 New in Isabelle99-1 (October 2000)
  1449 ----------------------------------
  1450 
  1451 *** Overview of INCOMPATIBILITIES ***
  1452 
  1453 * HOL: simplification of natural numbers is much changed; to partly
  1454 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
  1455 issue the following ML commands:
  1456 
  1457   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
  1458   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
  1459 
  1460 * HOL: simplification no longer dives into case-expressions; this is
  1461 controlled by "t.weak_case_cong" for each datatype t;
  1462 
  1463 * HOL: nat_less_induct renamed to less_induct;
  1464 
  1465 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
  1466 fixsome to patch .thy and .ML sources automatically;
  1467 
  1468   select_equality  -> some_equality
  1469   select_eq_Ex     -> some_eq_ex
  1470   selectI2EX       -> someI2_ex
  1471   selectI2         -> someI2
  1472   selectI          -> someI
  1473   select1_equality -> some1_equality
  1474   Eps_sym_eq       -> some_sym_eq_trivial
  1475   Eps_eq           -> some_eq_trivial
  1476 
  1477 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
  1478 
  1479 * HOL: removed obsolete theorem binding expand_if (refer to split_if
  1480 instead);
  1481 
  1482 * HOL: the recursion equations generated by 'recdef' are now called
  1483 f.simps instead of f.rules;
  1484 
  1485 * HOL: qed_spec_mp now also handles bounded ALL as well;
  1486 
  1487 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  1488 sometimes be needed;
  1489 
  1490 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  1491 
  1492 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  1493 
  1494 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  1495 product is now "<*>" instead of "Times"; the lexicographic product is
  1496 now "<*lex*>" instead of "**";
  1497 
  1498 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  1499 of main HOL, but was unused); better use HOL's datatype package;
  1500 
  1501 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  1502 the old syntax may be recovered as follows:
  1503 
  1504   syntax (symbols)
  1505     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  1506       (infixl "\\<oplus>" 100)
  1507 
  1508 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1509 
  1510 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1511 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1512 internally;
  1513 
  1514 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1515 changed from A/r to A//r;
  1516 
  1517 * ZF: new treatment of arithmetic (nat & int) may break some old
  1518 proofs;
  1519 
  1520 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1521 rulify -> rule_format, elimify -> elim_format, ...);
  1522 
  1523 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1524 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1525 should have to change intro!! to intro? only); replaced "delrule" by
  1526 "rule del";
  1527 
  1528 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1529 
  1530 * Provers: strengthened force_tac by using new first_best_tac;
  1531 
  1532 * LaTeX document preparation: several changes of isabelle.sty (see
  1533 lib/texinputs);
  1534 
  1535 
  1536 *** Document preparation ***
  1537 
  1538 * formal comments (text blocks etc.) in new-style theories may now
  1539 contain antiquotations of thm/prop/term/typ/text to be presented
  1540 according to latex print mode; concrete syntax is like this:
  1541 @{term[show_types] "f(x) = a + x"};
  1542 
  1543 * isatool mkdir provides easy setup of Isabelle session directories,
  1544 including proper document sources;
  1545 
  1546 * generated LaTeX sources are now deleted after successful run
  1547 (isatool document -c); may retain a copy somewhere else via -D option
  1548 of isatool usedir;
  1549 
  1550 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1551 style files, achieving self-contained LaTeX sources and simplifying
  1552 LaTeX debugging;
  1553 
  1554 * old-style theories now produce (crude) LaTeX output as well;
  1555 
  1556 * browser info session directories are now self-contained (may be put
  1557 on WWW server seperately); improved graphs of nested sessions; removed
  1558 graph for 'all sessions';
  1559 
  1560 * several improvements in isabelle style files; \isabellestyle{it}
  1561 produces fake math mode output; \isamarkupheader is now \section by
  1562 default; see lib/texinputs/isabelle.sty etc.;
  1563 
  1564 
  1565 *** Isar ***
  1566 
  1567 * Isar/Pure: local results and corresponding term bindings are now
  1568 subject to Hindley-Milner polymorphism (similar to ML); this
  1569 accommodates incremental type-inference very nicely;
  1570 
  1571 * Isar/Pure: new derived language element 'obtain' supports
  1572 generalized existence reasoning;
  1573 
  1574 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1575 support accumulation of results, without applying any rules yet;
  1576 useful to collect intermediate results without explicit name
  1577 references, and for use with transitivity rules with more than 2
  1578 premises;
  1579 
  1580 * Isar/Pure: scalable support for case-analysis type proofs: new
  1581 'case' language element refers to local contexts symbolically, as
  1582 produced by certain proof methods; internally, case names are attached
  1583 to theorems as "tags";
  1584 
  1585 * Isar/Pure: theory command 'hide' removes declarations from
  1586 class/type/const name spaces;
  1587 
  1588 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1589 indicate potential overloading;
  1590 
  1591 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1592 
  1593 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1594 "{a,b,c}" instead of {a,b,c};
  1595 
  1596 * Isar/Pure now provides its own version of intro/elim/dest
  1597 attributes; useful for building new logics, but beware of confusion
  1598 with the version in Provers/classical;
  1599 
  1600 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1601 case name 'antecedent';
  1602 
  1603 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1604 to the current context is now done automatically);
  1605 
  1606 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1607 for definining proof methods in ML;
  1608 
  1609 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1610 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1611 most cases, one should have to change intro!! to intro? only);
  1612 replaced "delrule" by "rule del";
  1613 
  1614 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1615 'symmetric' attribute (the latter supercedes [RS sym]);
  1616 
  1617 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1618 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1619 well (including splits);
  1620 
  1621 * Isar/Provers: Simplifier and Classical methods now support all kind
  1622 of modifiers used in the past, including 'cong', 'iff', etc.
  1623 
  1624 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1625 of Simplifier and Classical reasoner);
  1626 
  1627 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1628 now support named cases; major packages (inductive, datatype, primrec,
  1629 recdef) support case names and properly name parameters;
  1630 
  1631 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1632 monotonicity conditions are extracted to be proven at end of
  1633 calculations;
  1634 
  1635 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1636 method anyway;
  1637 
  1638 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1639 split_if split_if_asm; datatype package provides theorems foo.splits =
  1640 foo.split foo.split_asm for each datatype;
  1641 
  1642 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1643 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1644 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1645 use "(cases (simplified))" method in proper proof texts);
  1646 
  1647 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1648 
  1649 * Isar: names of theorems etc. may be natural numbers as well;
  1650 
  1651 * Isar: 'pr' command: optional arguments for goals_limit and
  1652 ProofContext.prems_limit; no longer prints theory contexts, but only
  1653 proof states;
  1654 
  1655 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1656 additional print modes to be specified; e.g. "pr(latex)" will print
  1657 proof state according to the Isabelle LaTeX style;
  1658 
  1659 * Isar: improved support for emulating tactic scripts, including proof
  1660 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1661 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1662 (for HOL datatypes);
  1663 
  1664 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1665 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1666 'proof method scripts' have to be in depth-first order;
  1667 
  1668 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1669 
  1670 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1671 should instead use individual commands for printing items
  1672 (print_commands, print_methods etc.);
  1673 
  1674 * Isar: added 'nothing' --- the empty list of theorems;
  1675 
  1676 
  1677 *** HOL ***
  1678 
  1679 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1680 corresponding virtual machine and a specification of its bytecode
  1681 verifier and a lightweight bytecode verifier, including proofs of
  1682 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1683 Cornelia Pusch (see also the homepage of project Bali at
  1684 http://isabelle.in.tum.de/Bali/);
  1685 
  1686 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1687 Clemens Ballarin;
  1688 
  1689 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1690 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1691 Rasmussen;
  1692 
  1693 * HOL/Lattice: fundamental concepts of lattice theory and order
  1694 structures, including duals, properties of bounds versus algebraic
  1695 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1696 Theorem for complete lattices etc.; may also serve as a demonstration
  1697 for abstract algebraic reasoning using axiomatic type classes, and
  1698 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1699 
  1700 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1701 von Oheimb;
  1702 
  1703 * HOL/IMPP: extension of IMP with local variables and mutually
  1704 recursive procedures, by David von Oheimb;
  1705 
  1706 * HOL/Lambda: converted into new-style theory and document;
  1707 
  1708 * HOL/ex/Multiquote: example of multiple nested quotations and
  1709 anti-quotations -- basically a generalized version of de-Bruijn
  1710 representation; very useful in avoiding lifting of operations;
  1711 
  1712 * HOL/record: added general record equality rule to simpset; fixed
  1713 select-update simplification procedure to handle extended records as
  1714 well; admit "r" as field name;
  1715 
  1716 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1717 other numeric types and also as the identity of groups, rings, etc.;
  1718 
  1719 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1720 Types nat and int belong to this axclass;
  1721 
  1722 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1723    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1724    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1725   two terms #m*u and #n*u are replaced by #(m+n)*u
  1726     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1727   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1728     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1729 
  1730 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1731 powerful prover for predicate logic but knows nothing of clasets; see
  1732 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1733 
  1734 * HOL: new version of "case_tac" subsumes both boolean case split and
  1735 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1736 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1737 
  1738 * HOL: simplification no longer dives into case-expressions: only the
  1739 selector expression is simplified, but not the remaining arms; to
  1740 enable full simplification of case-expressions for datatype t, you may
  1741 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1742 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1743 
  1744 * HOL/recdef: the recursion equations generated by 'recdef' for
  1745 function 'f' are now called f.simps instead of f.rules; if all
  1746 termination conditions are proved automatically, these simplification
  1747 rules are added to the simpset, as in primrec; rules may be named
  1748 individually as well, resulting in a separate list of theorems for
  1749 each equation;
  1750 
  1751 * HOL/While is a new theory that provides a while-combinator. It
  1752 permits the definition of tail-recursive functions without the
  1753 provision of a termination measure. The latter is necessary once the
  1754 invariant proof rule for while is applied.
  1755 
  1756 * HOL: new (overloaded) notation for the set of elements below/above
  1757 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1758 
  1759 * HOL: theorems impI, allI, ballI bound as "strip";
  1760 
  1761 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1762 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1763 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1764 
  1765 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1766 
  1767 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1768 main HOL, but was unused);
  1769 
  1770 * HOL: fewer consts declared as global (e.g. have to refer to
  1771 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1772 
  1773 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1774 in case of overlap with user translations (e.g. judgements over
  1775 tuples); (note that the underlying logical represenation is still
  1776 bogus);
  1777 
  1778 
  1779 *** ZF ***
  1780 
  1781 * ZF: simplification automatically cancels common terms in arithmetic
  1782 expressions over nat and int;
  1783 
  1784 * ZF: new treatment of nat to minimize type-checking: all operators
  1785 coerce their operands to a natural number using the function natify,
  1786 making the algebraic laws unconditional;
  1787 
  1788 * ZF: as above, for int: operators coerce their operands to an integer
  1789 using the function intify;
  1790 
  1791 * ZF: the integer library now contains many of the usual laws for the
  1792 orderings, including $<=, and monotonicity laws for $+ and $*;
  1793 
  1794 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1795 simplification;
  1796 
  1797 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1798 to the simplifier and classical reasoner simultaneously;
  1799 
  1800 
  1801 *** General ***
  1802 
  1803 * Provers: blast_tac now handles actual object-logic rules as
  1804 assumptions; note that auto_tac uses blast_tac internally as well;
  1805 
  1806 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1807 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1808 
  1809 * Provers: delrules now handles destruct rules as well (no longer need
  1810 explicit make_elim);
  1811 
  1812 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1813   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1814 use instead the strong form,
  1815   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1816 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1817 from destruct-rules;
  1818 
  1819 * Provers: Simplifier.easy_setup provides a fast path to basic
  1820 Simplifier setup for new object-logics;
  1821 
  1822 * Pure: AST translation rules no longer require constant head on LHS;
  1823 
  1824 * Pure: improved name spaces: ambiguous output is qualified; support
  1825 for hiding of names;
  1826 
  1827 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1828 XSYMBOL_HOME; no longer need to do manual configuration in most
  1829 situations;
  1830 
  1831 * system: compression of ML heaps images may now be controlled via -c
  1832 option of isabelle and isatool usedir (currently only observed by
  1833 Poly/ML);
  1834 
  1835 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1836 useful for remote X11);
  1837 
  1838 * system: provide TAGS file for Isabelle sources;
  1839 
  1840 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1841 order;
  1842 
  1843 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1844 timing flag supersedes proof_timing and Toplevel.trace;
  1845 
  1846 * ML: new combinators |>> and |>>> for incremental transformations
  1847 with secondary results (e.g. certain theory extensions):
  1848 
  1849 * ML: PureThy.add_defs gets additional argument to indicate potential
  1850 overloading (usually false);
  1851 
  1852 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1853 results;
  1854 
  1855 
  1856 
  1857 New in Isabelle99 (October 1999)
  1858 --------------------------------
  1859 
  1860 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1861 
  1862 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1863 are no longer simplified.  (This allows the simplifier to unfold recursive
  1864 functional programs.)  To restore the old behaviour, declare
  1865 
  1866     Delcongs [if_weak_cong];
  1867 
  1868 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1869 complement;
  1870 
  1871 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1872 
  1873 * HOL/datatype: mutual_induct_tac no longer exists --
  1874   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1875 
  1876 * HOL/typedef: fixed type inference for representing set; type
  1877 arguments now have to occur explicitly on the rhs as type constraints;
  1878 
  1879 * ZF: The con_defs part of an inductive definition may no longer refer
  1880 to constants declared in the same theory;
  1881 
  1882 * HOL, ZF: the function mk_cases, generated by the inductive
  1883 definition package, has lost an argument.  To simplify its result, it
  1884 uses the default simpset instead of a supplied list of theorems.
  1885 
  1886 * HOL/List: the constructors of type list are now Nil and Cons;
  1887 
  1888 * Simplifier: the type of the infix ML functions
  1889         setSSolver addSSolver setSolver addSolver
  1890 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1891 for packaging solvers. A solver is created via
  1892         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1893 where the string argument is only a comment.
  1894 
  1895 
  1896 *** Proof tools ***
  1897 
  1898 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1899 decision procedure for linear arithmetic. Currently it is used for
  1900 types `nat', `int', and `real' in HOL (see below); it can, should and
  1901 will be instantiated for other types and logics as well.
  1902 
  1903 * The simplifier now accepts rewrite rules with flexible heads, eg
  1904      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1905   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1906   matching.
  1907 
  1908 
  1909 *** General ***
  1910 
  1911 * New Isabelle/Isar subsystem provides an alternative to traditional
  1912 tactical theorem proving; together with the ProofGeneral/isar user
  1913 interface it offers an interactive environment for developing human
  1914 readable proof documents (Isar == Intelligible semi-automated
  1915 reasoning); for further information see isatool doc isar-ref,
  1916 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1917 
  1918 * improved and simplified presentation of theories: better HTML markup
  1919 (including colors), graph views in several sizes; isatool usedir now
  1920 provides a proper interface for user theories (via -P option); actual
  1921 document preparation based on (PDF)LaTeX is available as well (for
  1922 new-style theories only); see isatool doc system for more information;
  1923 
  1924 * native support for Proof General, both for classic Isabelle and
  1925 Isabelle/Isar;
  1926 
  1927 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1928 using the graph browser tool;
  1929 
  1930 * Isabelle manuals now also available as PDF;
  1931 
  1932 * theory loader rewritten from scratch (may not be fully
  1933 bug-compatible); old loadpath variable has been replaced by show_path,
  1934 add_path, del_path, reset_path functions; new operations such as
  1935 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1936 isatool doc ref);
  1937 
  1938 * improved isatool install: option -k creates KDE application icon,
  1939 option -p DIR installs standalone binaries;
  1940 
  1941 * added ML_PLATFORM setting (useful for cross-platform installations);
  1942 more robust handling of platform specific ML images for SML/NJ;
  1943 
  1944 * the settings environment is now statically scoped, i.e. it is never
  1945 created again in sub-processes invoked from isabelle, isatool, or
  1946 Isabelle;
  1947 
  1948 * path element specification '~~' refers to '$ISABELLE_HOME';
  1949 
  1950 * in locales, the "assumes" and "defines" parts may be omitted if
  1951 empty;
  1952 
  1953 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1954 long arrows);
  1955 
  1956 * new print_mode "HTML";
  1957 
  1958 * new flag show_tags controls display of tags of theorems (which are
  1959 basically just comments that may be attached by some tools);
  1960 
  1961 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1962 mode and goal output format:
  1963 
  1964 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1965 244c244
  1966 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1967 ---
  1968 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1969 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1970 181c181
  1971 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1972 ---
  1973 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1974 
  1975 * function bind_thms stores lists of theorems (cf. bind_thm);
  1976 
  1977 * new shorthand tactics ftac, eatac, datac, fatac;
  1978 
  1979 * qed (and friends) now accept "" as result name; in that case the
  1980 theorem is not stored, but proper checks and presentation of the
  1981 result still apply;
  1982 
  1983 * theorem database now also indexes constants "Trueprop", "all",
  1984 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1985 
  1986 
  1987 *** HOL ***
  1988 
  1989 ** HOL arithmetic **
  1990 
  1991 * There are now decision procedures for linear arithmetic over nat and
  1992 int:
  1993 
  1994 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1995 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1996 are treated as atomic; subformulae not involving type `nat' or `int'
  1997 are ignored; quantified subformulae are ignored unless they are
  1998 positive universal or negative existential. The tactic has to be
  1999 invoked by hand and can be a little bit slow. In particular, the
  2000 running time is exponential in the number of occurrences of `min' and
  2001 `max', and `-' on `nat'.
  2002 
  2003 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  2004 (negated) (in)equalities among the premises and the conclusion into
  2005 account (i.e. no compound formulae) and does not know about `min' and
  2006 `max', and `-' on `nat'. It is fast and is used automatically by the
  2007 simplifier.
  2008 
  2009 NB: At the moment, these decision procedures do not cope with mixed
  2010 nat/int formulae where the two parts interact, such as `m < n ==>
  2011 int(m) < int(n)'.
  2012 
  2013 * HOL/Numeral provides a generic theory of numerals (encoded
  2014 efficiently as bit strings); setup for types nat/int/real is in place;
  2015 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  2016 int, existing theories and proof scripts may require a few additional
  2017 type constraints;
  2018 
  2019 * integer division and remainder can now be performed on constant
  2020 arguments;
  2021 
  2022 * many properties of integer multiplication, division and remainder
  2023 are now available;
  2024 
  2025 * An interface to the Stanford Validity Checker (SVC) is available through the
  2026 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  2027 are proved automatically.  SVC must be installed separately, and its results
  2028 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  2029 invocation of the underlying oracle).  For SVC see
  2030   http://verify.stanford.edu/SVC
  2031 
  2032 * IsaMakefile: the HOL-Real target now builds an actual image;
  2033 
  2034 
  2035 ** HOL misc **
  2036 
  2037 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  2038 (in Isabelle/Isar) -- by Gertrud Bauer;
  2039 
  2040 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  2041 analysis for assembly languages with subtypes;
  2042 
  2043 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  2044 -- avoids syntactic ambiguities and treats state, transition, and
  2045 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  2046 changed syntax and (many) tactics;
  2047 
  2048 * HOL/inductive: Now also handles more general introduction rules such
  2049   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  2050   theorems are now maintained within the theory (maintained via the
  2051   "mono" attribute);
  2052 
  2053 * HOL/datatype: Now also handles arbitrarily branching datatypes
  2054   (using function types) such as
  2055 
  2056   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  2057 
  2058 * HOL/record: record_simproc (part of the default simpset) takes care
  2059 of selectors applied to updated records; record_split_tac is no longer
  2060 part of the default claset; update_defs may now be removed from the
  2061 simpset in many cases; COMPATIBILITY: old behavior achieved by
  2062 
  2063   claset_ref () := claset() addSWrapper record_split_wrapper;
  2064   Delsimprocs [record_simproc]
  2065 
  2066 * HOL/typedef: fixed type inference for representing set; type
  2067 arguments now have to occur explicitly on the rhs as type constraints;
  2068 
  2069 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  2070 names rather than an ML expression;
  2071 
  2072 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  2073 supplied later.  Program schemes can be defined, such as
  2074     "While B C s = (if B s then While B C (C s) else s)"
  2075 where the well-founded relation can be chosen after B and C have been given.
  2076 
  2077 * HOL/List: the constructors of type list are now Nil and Cons;
  2078 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  2079 course, ML tools referring to List.list.op # etc. have to be adapted;
  2080 
  2081 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  2082 disabled by default; run isabelle with option -m HOL to get back to
  2083 the original Gordon/HOL-style output;
  2084 
  2085 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  2086 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  2087 
  2088 * HOL basic syntax simplified (more orthogonal): all variants of
  2089 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  2090 Eps operator is provided as well: "SOME x. P[x]";
  2091 
  2092 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  2093 
  2094 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  2095 thus available for user theories;
  2096 
  2097 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  2098 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  2099 time;
  2100 
  2101 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  2102 several times and then mp;
  2103 
  2104 
  2105 *** LK ***
  2106 
  2107 * the notation <<...>> is now available as a notation for sequences of
  2108 formulas;
  2109 
  2110 * the simplifier is now installed
  2111 
  2112 * the axiom system has been generalized (thanks to Soren Heilmann)
  2113 
  2114 * the classical reasoner now has a default rule database
  2115 
  2116 
  2117 *** ZF ***
  2118 
  2119 * new primrec section allows primitive recursive functions to be given
  2120 directly (as in HOL) over datatypes and the natural numbers;
  2121 
  2122 * new tactics induct_tac and exhaust_tac for induction (or case
  2123 analysis) over datatypes and the natural numbers;
  2124 
  2125 * the datatype declaration of type T now defines the recursor T_rec;
  2126 
  2127 * simplification automatically does freeness reasoning for datatype
  2128 constructors;
  2129 
  2130 * automatic type-inference, with AddTCs command to insert new
  2131 type-checking rules;
  2132 
  2133 * datatype introduction rules are now added as Safe Introduction rules
  2134 to the claset;
  2135 
  2136 * the syntax "if P then x else y" is now available in addition to
  2137 if(P,x,y);
  2138 
  2139 
  2140 *** Internal programming interfaces ***
  2141 
  2142 * tuned simplifier trace output; new flag debug_simp;
  2143 
  2144 * structures Vartab / Termtab (instances of TableFun) offer efficient
  2145 tables indexed by indexname_ord / term_ord (compatible with aconv);
  2146 
  2147 * AxClass.axclass_tac lost the theory argument;
  2148 
  2149 * tuned current_goals_markers semantics: begin / end goal avoids
  2150 printing empty lines;
  2151 
  2152 * removed prs and prs_fn hook, which was broken because it did not
  2153 include \n in its semantics, forcing writeln to add one
  2154 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  2155 string -> unit if you really want to output text without newline;
  2156 
  2157 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  2158 plain output, interface builders may have to enable 'isabelle_font'
  2159 mode to get Isabelle font glyphs as before;
  2160 
  2161 * refined token_translation interface; INCOMPATIBILITY: output length
  2162 now of type real instead of int;
  2163 
  2164 * theory loader actions may be traced via new ThyInfo.add_hook
  2165 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  2166 your own database of information attached to *whole* theories -- as
  2167 opposed to intra-theory data slots offered via TheoryDataFun;
  2168 
  2169 * proper handling of dangling sort hypotheses (at last!);
  2170 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  2171 extra sort hypotheses that can be witnessed from the type signature;
  2172 the force_strip_shyps flag is gone, any remaining shyps are simply
  2173 left in the theorem (with a warning issued by strip_shyps_warning);
  2174 
  2175 
  2176 
  2177 New in Isabelle98-1 (October 1998)
  2178 ----------------------------------
  2179 
  2180 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2181 
  2182 * several changes of automated proof tools;
  2183 
  2184 * HOL: major changes to the inductive and datatype packages, including
  2185 some minor incompatibilities of theory syntax;
  2186 
  2187 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  2188 called `inj_on';
  2189 
  2190 * HOL: removed duplicate thms in Arith:
  2191   less_imp_add_less  should be replaced by  trans_less_add1
  2192   le_imp_add_le      should be replaced by  trans_le_add1
  2193 
  2194 * HOL: unary minus is now overloaded (new type constraints may be
  2195 required);
  2196 
  2197 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  2198 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  2199 now taken as an integer constant.
  2200 
  2201 * Pure: ML function 'theory_of' renamed to 'theory';
  2202 
  2203 
  2204 *** Proof tools ***
  2205 
  2206 * Simplifier:
  2207   1. Asm_full_simp_tac is now more aggressive.
  2208      1. It will sometimes reorient premises if that increases their power to
  2209         simplify.
  2210      2. It does no longer proceed strictly from left to right but may also
  2211         rotate premises to achieve further simplification.
  2212      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  2213      old Asm_full_simp_tac in that it does not rotate premises.
  2214   2. The simplifier now knows a little bit about nat-arithmetic.
  2215 
  2216 * Classical reasoner: wrapper mechanism for the classical reasoner now
  2217 allows for selected deletion of wrappers, by introduction of names for
  2218 wrapper functionals.  This implies that addbefore, addSbefore,
  2219 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  2220 and that adding two tactics with the same name overwrites the first
  2221 one (emitting a warning).
  2222   type wrapper = (int -> tactic) -> (int -> tactic)
  2223   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  2224   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  2225   delWrapper, delSWrapper: claset *  string            -> claset
  2226   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  2227 
  2228 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  2229 semantics; addbefore now affects only the unsafe part of step_tac
  2230 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  2231 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  2232 by Force_tac;
  2233 
  2234 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  2235 compWrapper; added safe wrapper (and access functions for it);
  2236 
  2237 * HOL/split_all_tac is now much faster and fails if there is nothing
  2238 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  2239 and the names of the automatically generated variables have changed.
  2240 split_all_tac has moved within claset() from unsafe wrappers to safe
  2241 wrappers, which means that !!-bound variables are split much more
  2242 aggressively, and safe_tac and clarify_tac now split such variables.
  2243 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  2244 Note: the same holds for record_split_tac, which does the job of
  2245 split_all_tac for record fields.
  2246 
  2247 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  2248 permanently to the default simpset using Addsplits just like
  2249 Addsimps. They can be removed via Delsplits just like
  2250 Delsimps. Lower-case versions are also available.
  2251 
  2252 * HOL/Simplifier: The rule split_if is now part of the default
  2253 simpset. This means that the simplifier will eliminate all occurrences
  2254 of if-then-else in the conclusion of a goal. To prevent this, you can
  2255 either remove split_if completely from the default simpset by
  2256 `Delsplits [split_if]' or remove it in a specific call of the
  2257 simplifier using `... delsplits [split_if]'.  You can also add/delete
  2258 other case splitting rules to/from the default simpset: every datatype
  2259 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  2260 t is the name of the datatype).
  2261 
  2262 * Classical reasoner / Simplifier combination: new force_tac (and
  2263 derivatives Force_tac, force) combines rewriting and classical
  2264 reasoning (and whatever other tools) similarly to auto_tac, but is
  2265 aimed to solve the given subgoal completely.
  2266 
  2267 
  2268 *** General ***
  2269 
  2270 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  2271 and `goalw': the theory is no longer needed as an explicit argument -
  2272 the current theory context is used; assumptions are no longer returned
  2273 at the ML-level unless one of them starts with ==> or !!; it is
  2274 recommended to convert to these new commands using isatool fixgoal
  2275 (backup your sources first!);
  2276 
  2277 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  2278 the current theory context, and 'theory' to lookup stored theories;
  2279 
  2280 * new theory section 'locale' for declaring constants, assumptions and
  2281 definitions that have local scope;
  2282 
  2283 * new theory section 'nonterminals' for purely syntactic types;
  2284 
  2285 * new theory section 'setup' for generic ML setup functions
  2286 (e.g. package initialization);
  2287 
  2288 * the distribution now includes Isabelle icons: see
  2289 lib/logo/isabelle-{small,tiny}.xpm;
  2290 
  2291 * isatool install - install binaries with absolute references to
  2292 ISABELLE_HOME/bin;
  2293 
  2294 * isatool logo -- create instances of the Isabelle logo (as EPS);
  2295 
  2296 * print mode 'emacs' reserved for Isamode;
  2297 
  2298 * support multiple print (ast) translations per constant name;
  2299 
  2300 * theorems involving oracles are now printed with a suffixed [!];
  2301 
  2302 
  2303 *** HOL ***
  2304 
  2305 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  2306 
  2307 * HOL/inductive package reorganized and improved: now supports mutual
  2308 definitions such as
  2309 
  2310   inductive EVEN ODD
  2311     intrs
  2312       null "0 : EVEN"
  2313       oddI "n : EVEN ==> Suc n : ODD"
  2314       evenI "n : ODD ==> Suc n : EVEN"
  2315 
  2316 new theorem list "elims" contains an elimination rule for each of the
  2317 recursive sets; inductive definitions now handle disjunctive premises
  2318 correctly (also ZF);
  2319 
  2320 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  2321 "mutual_induct" no longer exists - the induction rule is always
  2322 contained in "induct";
  2323 
  2324 
  2325 * HOL/datatype package re-implemented and greatly improved: now
  2326 supports mutually recursive datatypes such as
  2327 
  2328   datatype
  2329     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  2330             | SUM ('a aexp) ('a aexp)
  2331             | DIFF ('a aexp) ('a aexp)
  2332             | NUM 'a
  2333   and
  2334     'a bexp = LESS ('a aexp) ('a aexp)
  2335             | AND ('a bexp) ('a bexp)
  2336             | OR ('a bexp) ('a bexp)
  2337 
  2338 as well as indirectly recursive datatypes such as
  2339 
  2340   datatype
  2341     ('a, 'b) term = Var 'a
  2342                   | App 'b ((('a, 'b) term) list)
  2343 
  2344 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  2345 induction on mutually / indirectly recursive datatypes.
  2346 
  2347 Primrec equations are now stored in theory and can be accessed via
  2348 <function_name>.simps.
  2349 
  2350 INCOMPATIBILITIES:
  2351 
  2352   - Theories using datatypes must now have theory Datatype as an
  2353     ancestor.
  2354   - The specific <typename>.induct_tac no longer exists - use the
  2355     generic induct_tac instead.
  2356   - natE has been renamed to nat.exhaust - use exhaust_tac
  2357     instead of res_inst_tac ... natE. Note that the variable
  2358     names in nat.exhaust differ from the names in natE, this
  2359     may cause some "fragile" proofs to fail.
  2360   - The theorems split_<typename>_case and split_<typename>_case_asm
  2361     have been renamed to <typename>.split and <typename>.split_asm.
  2362   - Since default sorts of type variables are now handled correctly,
  2363     some datatype definitions may have to be annotated with explicit
  2364     sort constraints.
  2365   - Primrec definitions no longer require function name and type
  2366     of recursive argument.
  2367 
  2368 Consider using isatool fixdatatype to adapt your theories and proof
  2369 scripts to the new package (backup your sources first!).
  2370 
  2371 
  2372 * HOL/record package: considerably improved implementation; now
  2373 includes concrete syntax for record types, terms, updates; theorems
  2374 for surjective pairing and splitting !!-bound record variables; proof
  2375 support is as follows:
  2376 
  2377   1) standard conversions (selectors or updates applied to record
  2378 constructor terms) are part of the standard simpset;
  2379 
  2380   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  2381 made part of standard simpset and claset via addIffs;
  2382 
  2383   3) a tactic for record field splitting (record_split_tac) is part of
  2384 the standard claset (addSWrapper);
  2385 
  2386 To get a better idea about these rules you may retrieve them via
  2387 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  2388 the name of your record type.
  2389 
  2390 The split tactic 3) conceptually simplifies by the following rule:
  2391 
  2392   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  2393 
  2394 Thus any record variable that is bound by meta-all will automatically
  2395 blow up into some record constructor term, consequently the
  2396 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  2397 solve record problems automatically.
  2398 
  2399 
  2400 * reorganized the main HOL image: HOL/Integ and String loaded by
  2401 default; theory Main includes everything;
  2402 
  2403 * automatic simplification of integer sums and comparisons, using cancellation;
  2404 
  2405 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  2406 
  2407 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  2408 
  2409 * many new identities for unions, intersections, set difference, etc.;
  2410 
  2411 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  2412 called split_if, split_split, split_sum_case and split_nat_case (to go
  2413 with add/delsplits);
  2414 
  2415 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  2416 (?x::unit) = (); this is made part of the default simpset, which COULD
  2417 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  2418 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  2419 unit_abs_eta_conv is added in order to counter the effect of
  2420 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  2421 %u.f();
  2422 
  2423 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  2424 makes more sense);
  2425 
  2426 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2427   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2428   disjointness reasoning but breaking a few old proofs.
  2429 
  2430 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  2431 to 'converse' from 'inverse' (for compatibility with ZF and some
  2432 literature);
  2433 
  2434 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  2435 the well-founded relation;
  2436 
  2437 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  2438     Compl A.  The "Compl" syntax remains available as input syntax for this
  2439     release ONLY.
  2440 
  2441 * HOL/Update: new theory of function updates:
  2442     f(a:=b) == %x. if x=a then b else f x
  2443 may also be iterated as in f(a:=b,c:=d,...);
  2444 
  2445 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  2446 
  2447 * HOL/List:
  2448   - new function list_update written xs[i:=v] that updates the i-th
  2449     list position. May also be iterated as in xs[i:=a,j:=b,...].
  2450   - new function `upt' written [i..j(] which generates the list
  2451     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  2452     bound write [i..j], which is a shorthand for [i..j+1(].
  2453   - new lexicographic orderings and corresponding wellfoundedness theorems.
  2454 
  2455 * HOL/Arith:
  2456   - removed 'pred' (predecessor) function;
  2457   - generalized some theorems about n-1;
  2458   - many new laws about "div" and "mod";
  2459   - new laws about greatest common divisors (see theory ex/Primes);
  2460 
  2461 * HOL/Relation: renamed the relational operator r^-1 "converse"
  2462 instead of "inverse";
  2463 
  2464 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  2465   of the multiset ordering;
  2466 
  2467 * directory HOL/Real: a construction of the reals using Dedekind cuts
  2468   (not included by default);
  2469 
  2470 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  2471 
  2472 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  2473   programs, i.e. different program variables may have different types.
  2474 
  2475 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2476   [previously, this check worked only if the rewrite rule was unconditional]
  2477   Now rew can involve either definitions or equalities (either == or =).
  2478 
  2479 
  2480 *** ZF ***
  2481 
  2482 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  2483   only the theorems proved on ZF.ML;
  2484 
  2485 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2486   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2487   disjointness reasoning but breaking a few old proofs.
  2488 
  2489 * ZF/Update: new theory of function updates
  2490     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  2491   may also be iterated as in f(a:=b,c:=d,...);
  2492 
  2493 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  2494 
  2495 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2496   [previously, this check worked only if the rewrite rule was unconditional]
  2497   Now rew can involve either definitions or equalities (either == or =).
  2498 
  2499 * case_tac provided for compatibility with HOL
  2500     (like the old excluded_middle_tac, but with subgoals swapped)
  2501 
  2502 
  2503 *** Internal programming interfaces ***
  2504 
  2505 * Pure: several new basic modules made available for general use, see
  2506 also src/Pure/README;
  2507 
  2508 * improved the theory data mechanism to support encapsulation (data
  2509 kind name replaced by private Object.kind, acting as authorization
  2510 key); new type-safe user interface via functor TheoryDataFun; generic
  2511 print_data function becomes basically useless;
  2512 
  2513 * removed global_names compatibility flag -- all theory declarations
  2514 are qualified by default;
  2515 
  2516 * module Pure/Syntax now offers quote / antiquote translation
  2517 functions (useful for Hoare logic etc. with implicit dependencies);
  2518 see HOL/ex/Antiquote for an example use;
  2519 
  2520 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2521 cterm -> thm;
  2522 
  2523 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2524 subgoal;
  2525 
  2526 * Display.print_goals function moved to Locale.print_goals;
  2527 
  2528 * standard print function for goals supports current_goals_markers
  2529 variable for marking begin of proof, end of proof, start of goal; the
  2530 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2531 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2532 for example;
  2533 
  2534 
  2535 
  2536 New in Isabelle98 (January 1998)
  2537 --------------------------------
  2538 
  2539 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2540 
  2541 * changed lexical syntax of terms / types: dots made part of long
  2542 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2543 
  2544 * simpset (and claset) reference variable replaced by functions
  2545 simpset / simpset_ref;
  2546 
  2547 * no longer supports theory aliases (via merge) and non-trivial
  2548 implicit merge of thms' signatures;
  2549 
  2550 * most internal names of constants changed due to qualified names;
  2551 
  2552 * changed Pure/Sequence interface (see Pure/seq.ML);
  2553 
  2554 
  2555 *** General Changes ***
  2556 
  2557 * hierachically structured name spaces (for consts, types, axms, thms
  2558 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2559 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2560 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2561 long_names for fully qualified output names; NOTE: ML programs
  2562 (special tactics, packages etc.) referring to internal names may have
  2563 to be adapted to cope with fully qualified names; in case of severe
  2564 backward campatibility problems try setting 'global_names' at compile
  2565 time to have enrything declared within a flat name space; one may also
  2566 fine tune name declarations in theories via the 'global' and 'local'
  2567 section;
  2568 
  2569 * reimplemented the implicit simpset and claset using the new anytype
  2570 data filed in signatures; references simpset:simpset ref etc. are
  2571 replaced by functions simpset:unit->simpset and
  2572 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2573 to patch your ML files accordingly;
  2574 
  2575 * HTML output now includes theory graph data for display with Java
  2576 applet or isatool browser; data generated automatically via isatool
  2577 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2578 
  2579 * defs may now be conditional; improved rewrite_goals_tac to handle
  2580 conditional equations;
  2581 
  2582 * defs now admits additional type arguments, using TYPE('a) syntax;
  2583 
  2584 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2585 creates a new theory node; implicit merge of thms' signatures is
  2586 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2587 transfer:theory->thm->thm in (rare) cases;
  2588 
  2589 * improved handling of draft signatures / theories; draft thms (and
  2590 ctyps, cterms) are automatically promoted to real ones;
  2591 
  2592 * slightly changed interfaces for oracles: admit many per theory, named
  2593 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2594 
  2595 * print_goals: optional output of const types (set show_consts and
  2596 show_types);
  2597 
  2598 * improved output of warnings (###) and errors (***);
  2599 
  2600 * subgoal_tac displays a warning if the new subgoal has type variables;
  2601 
  2602 * removed old README and Makefiles;
  2603 
  2604 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2605 
  2606 * removed obsolete init_pps and init_database;
  2607 
  2608 * deleted the obsolete tactical STATE, which was declared by
  2609     fun STATE tacfun st = tacfun st st;
  2610 
  2611 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2612 (which abbreviates $HOME);
  2613 
  2614 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2615 use isatool fixseq to adapt your ML programs (this works for fully
  2616 qualified references to the Sequence structure only!);
  2617 
  2618 * use_thy no longer requires writable current directory; it always
  2619 reloads .ML *and* .thy file, if either one is out of date;
  2620 
  2621 
  2622 *** Classical Reasoner ***
  2623 
  2624 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2625 tactics that use classical reasoning to simplify a subgoal without
  2626 splitting it into several subgoals;
  2627 
  2628 * Safe_tac: like safe_tac but uses the default claset;
  2629 
  2630 
  2631 *** Simplifier ***
  2632 
  2633 * added simplification meta rules:
  2634     (asm_)(full_)simplify: simpset -> thm -> thm;
  2635 
  2636 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2637 logics (again);
  2638 
  2639 * added prems argument to simplification procedures;
  2640 
  2641 * HOL, FOL, ZF: added infix function `addsplits':
  2642   instead of `<simpset> setloop (split_tac <thms>)'
  2643   you can simply write `<simpset> addsplits <thms>'
  2644 
  2645 
  2646 *** Syntax ***
  2647 
  2648 * TYPE('a) syntax for type reflection terms;
  2649 
  2650 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2651 
  2652 * pretty printer: changed order of mixfix annotation preference (again!);
  2653 
  2654 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2655 
  2656 
  2657 *** HOL ***
  2658 
  2659 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2660   with `addloop' of the simplifier to faciliate case splitting in premises.
  2661 
  2662 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2663 
  2664 * HOL/Auth: new protocol proofs including some for the Internet
  2665   protocol TLS;
  2666 
  2667 * HOL/Map: new theory of `maps' a la VDM;
  2668 
  2669 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2670 cancelling out common nat summands from =, <, <= (in)equalities, or
  2671 differences; simplification procedures nat_cancel_factor for
  2672 cancelling common factor from =, <, <= (in)equalities over natural
  2673 sums; nat_cancel contains both kinds of procedures, it is installed by
  2674 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2675 
  2676 * HOL/simplifier: terms of the form
  2677   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2678   are rewritten to
  2679   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2680   and those of the form
  2681   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2682   are rewritten to
  2683   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2684 
  2685 * HOL/datatype
  2686   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2687 
  2688   P(t_case f1 ... fn x) =
  2689      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2690         ...
  2691        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2692      )
  2693 
  2694   and a theorem `split_t_case_asm' of the form
  2695 
  2696   P(t_case f1 ... fn x) =
  2697     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2698         ...
  2699        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2700      )
  2701   which can be added to a simpset via `addsplits'. The existing theorems
  2702   expand_list_case and expand_option_case have been renamed to
  2703   split_list_case and split_option_case.
  2704 
  2705 * HOL/Arithmetic:
  2706   - `pred n' is automatically converted to `n-1'.
  2707     Users are strongly encouraged not to use `pred' any longer,
  2708     because it will disappear altogether at some point.
  2709   - Users are strongly encouraged to write "0 < n" rather than
  2710     "n ~= 0". Theorems and proof tools have been modified towards this
  2711     `standard'.
  2712 
  2713 * HOL/Lists:
  2714   the function "set_of_list" has been renamed "set" (and its theorems too);
  2715   the function "nth" now takes its arguments in the reverse order and
  2716   has acquired the infix notation "!" as in "xs!n".
  2717 
  2718 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2719 
  2720 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2721   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2722 
  2723 * HOL/record: extensible records with schematic structural subtyping
  2724 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2725 still lacks various theorems and concrete record syntax;
  2726 
  2727 
  2728 *** HOLCF ***
  2729 
  2730 * removed "axioms" and "generated by" sections;
  2731 
  2732 * replaced "ops" section by extended "consts" section, which is capable of
  2733   handling the continuous function space "->" directly;
  2734 
  2735 * domain package:
  2736   . proves theorems immediately and stores them in the theory,
  2737   . creates hierachical name space,
  2738   . now uses normal mixfix annotations (instead of cinfix...),
  2739   . minor changes to some names and values (for consistency),
  2740   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2741   . separator between mutual domain defs: changed "," to "and",
  2742   . improved handling of sort constraints;  now they have to
  2743     appear on the left-hand side of the equations only;
  2744 
  2745 * fixed LAM <x,y,zs>.b syntax;
  2746 
  2747 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2748 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2749 
  2750 
  2751 *** FOL and ZF ***
  2752 
  2753 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2754   with `addloop' of the simplifier to faciliate case splitting in premises.
  2755 
  2756 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2757 in HOL, they strip ALL and --> from proved theorems;
  2758 
  2759 
  2760 
  2761 New in Isabelle94-8 (May 1997)
  2762 ------------------------------
  2763 
  2764 *** General Changes ***
  2765 
  2766 * new utilities to build / run / maintain Isabelle etc. (in parts
  2767 still somewhat experimental); old Makefiles etc. still functional;
  2768 
  2769 * new 'Isabelle System Manual';
  2770 
  2771 * INSTALL text, together with ./configure and ./build scripts;
  2772 
  2773 * reimplemented type inference for greater efficiency, better error
  2774 messages and clean internal interface;
  2775 
  2776 * prlim command for dealing with lots of subgoals (an easier way of
  2777 setting goals_limit);
  2778 
  2779 
  2780 *** Syntax ***
  2781 
  2782 * supports alternative (named) syntax tables (parser and pretty
  2783 printer); internal interface is provided by add_modesyntax(_i);
  2784 
  2785 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2786 be used in conjunction with the Isabelle symbol font; uses the
  2787 "symbols" syntax table;
  2788 
  2789 * added token_translation interface (may translate name tokens in
  2790 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2791 the current print_mode); IMPORTANT: user print translation functions
  2792 are responsible for marking newly introduced bounds
  2793 (Syntax.mark_boundT);
  2794 
  2795 * token translations for modes "xterm" and "xterm_color" that display
  2796 names in bold, underline etc. or colors (which requires a color
  2797 version of xterm);
  2798 
  2799 * infixes may now be declared with names independent of their syntax;
  2800 
  2801 * added typed_print_translation (like print_translation, but may
  2802 access type of constant);
  2803 
  2804 
  2805 *** Classical Reasoner ***
  2806 
  2807 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2808 some limitations.  Blast_tac...
  2809   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2810   + ignores elimination rules that don't have the correct format
  2811         (the conclusion MUST be a formula variable)
  2812   + ignores types, which can make HOL proofs fail
  2813   + rules must not require higher-order unification, e.g. apply_type in ZF
  2814     [message "Function Var's argument not a bound variable" relates to this]
  2815   + its proof strategy is more general but can actually be slower
  2816 
  2817 * substitution with equality assumptions no longer permutes other
  2818 assumptions;
  2819 
  2820 * minor changes in semantics of addafter (now called addaltern); renamed
  2821 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2822 (and access functions for it);
  2823 
  2824 * improved combination of classical reasoner and simplifier:
  2825   + functions for handling clasimpsets
  2826   + improvement of addss: now the simplifier is called _after_ the
  2827     safe steps.
  2828   + safe variant of addss called addSss: uses safe simplifications
  2829     _during_ the safe steps. It is more complete as it allows multiple
  2830     instantiations of unknowns (e.g. with slow_tac).
  2831 
  2832 *** Simplifier ***
  2833 
  2834 * added interface for simplification procedures (functions that
  2835 produce *proven* rewrite rules on the fly, depending on current
  2836 redex);
  2837 
  2838 * ordering on terms as parameter (used for ordered rewriting);
  2839 
  2840 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2841 
  2842 * the solver is now split into a safe and an unsafe part.
  2843 This should be invisible for the normal user, except that the
  2844 functions setsolver and addsolver have been renamed to setSolver and
  2845 addSolver; added safe_asm_full_simp_tac;
  2846 
  2847 
  2848 *** HOL ***
  2849 
  2850 * a generic induction tactic `induct_tac' which works for all datatypes and
  2851 also for type `nat';
  2852 
  2853 * a generic case distinction tactic `exhaust_tac' which works for all
  2854 datatypes and also for type `nat';
  2855 
  2856 * each datatype comes with a function `size';
  2857 
  2858 * patterns in case expressions allow tuple patterns as arguments to
  2859 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2860 
  2861 * primrec now also works with type nat;
  2862 
  2863 * recdef: a new declaration form, allows general recursive functions to be
  2864 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2865 
  2866 * the constant for negation has been renamed from "not" to "Not" to
  2867 harmonize with FOL, ZF, LK, etc.;
  2868 
  2869 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2870 infinite lists;
  2871 
  2872 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2873 
  2874 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2875 problems in commutative rings, using axiomatic type classes for + and *;
  2876 
  2877 * more examples in HOL/MiniML and HOL/Auth;
  2878 
  2879 * more default rewrite rules for quantifiers, union/intersection;
  2880 
  2881 * a new constant `arbitrary == @x.False';
  2882 
  2883 * HOLCF/IOA replaces old HOL/IOA;
  2884 
  2885 * HOLCF changes: derived all rules and arities
  2886   + axiomatic type classes instead of classes
  2887   + typedef instead of faking type definitions
  2888   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2889   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2890   + eliminated the types void, one, tr
  2891   + use unit lift and bool lift (with translations) instead of one and tr
  2892   + eliminated blift from Lift3.thy (use Def instead of blift)
  2893   all eliminated rules are derived as theorems --> no visible changes ;
  2894 
  2895 
  2896 *** ZF ***
  2897 
  2898 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2899 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2900 as ZF_cs addSIs [equalityI];
  2901 
  2902 
  2903 
  2904 New in Isabelle94-7 (November 96)
  2905 ---------------------------------
  2906 
  2907 * allowing negative levels (as offsets) in prlev and choplev;
  2908 
  2909 * super-linear speedup for large simplifications;
  2910 
  2911 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2912 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2913 FAIL); can suppress it using the command Delsimps (ex_simps @
  2914 all_simps); De Morgan laws are also now included, by default;
  2915 
  2916 * improved printing of ==>  :  ~:
  2917 
  2918 * new object-logic "Sequents" adds linear logic, while replacing LK
  2919 and Modal (thanks to Sara Kalvala);
  2920 
  2921 * HOL/Auth: correctness proofs for authentication protocols;
  2922 
  2923 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2924 examples on HOL/Auth);
  2925 
  2926 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2927 the rewriter and classical reasoner simultaneously;
  2928 
  2929 * function uresult no longer returns theorems in "standard" format;
  2930 regain previous version by: val uresult = standard o uresult;
  2931 
  2932 
  2933 
  2934 New in Isabelle94-6
  2935 -------------------
  2936 
  2937 * oracles -- these establish an interface between Isabelle and trusted
  2938 external reasoners, which may deliver results as theorems;
  2939 
  2940 * proof objects (in particular record all uses of oracles);
  2941 
  2942 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2943 
  2944 * "constdefs" section in theory files;
  2945 
  2946 * "primrec" section (HOL) no longer requires names;
  2947 
  2948 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2949 
  2950 
  2951 
  2952 New in Isabelle94-5
  2953 -------------------
  2954 
  2955 * reduced space requirements;
  2956 
  2957 * automatic HTML generation from theories;
  2958 
  2959 * theory files no longer require "..." (quotes) around most types;
  2960 
  2961 * new examples, including two proofs of the Church-Rosser theorem;
  2962 
  2963 * non-curried (1994) version of HOL is no longer distributed;
  2964 
  2965 
  2966 
  2967 New in Isabelle94-4
  2968 -------------------
  2969 
  2970 * greatly reduced space requirements;
  2971 
  2972 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2973 
  2974 * searchable theorem database (see the section "Retrieving theorems" on
  2975 page 8 of the Reference Manual);
  2976 
  2977 * new examples, including Grabczewski's monumental case study of the
  2978 Axiom of Choice;
  2979 
  2980 * The previous version of HOL renamed to Old_HOL;
  2981 
  2982 * The new version of HOL (previously called CHOL) uses a curried syntax
  2983 for functions.  Application looks like f a b instead of f(a,b);
  2984 
  2985 * Mutually recursive inductive definitions finally work in HOL;
  2986 
  2987 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2988 translates to the operator "split";
  2989 
  2990 
  2991 
  2992 New in Isabelle94-3
  2993 -------------------
  2994 
  2995 * new infix operator, addss, allowing the classical reasoner to
  2996 perform simplification at each step of its search.  Example:
  2997         fast_tac (cs addss ss)
  2998 
  2999 * a new logic, CHOL, the same as HOL, but with a curried syntax
  3000 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  3001 look like (a,b) instead of <a,b>;
  3002 
  3003 * PLEASE NOTE: CHOL will eventually replace HOL!
  3004 
  3005 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  3006 It translates to the operator "split".  A new theory of integers is available;
  3007 
  3008 * In ZF, integer numerals now denote two's-complement binary integers.
  3009 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  3010 
  3011 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  3012 of the Axiom of Choice;
  3013 
  3014 
  3015 
  3016 New in Isabelle94-2
  3017 -------------------
  3018 
  3019 * Significantly faster resolution;
  3020 
  3021 * the different sections in a .thy file can now be mixed and repeated
  3022 freely;
  3023 
  3024 * Database of theorems for FOL, HOL and ZF.  New
  3025 commands including qed, qed_goal and bind_thm store theorems in the database.
  3026 
  3027 * Simple database queries: return a named theorem (get_thm) or all theorems of
  3028 a given theory (thms_of), or find out what theory a theorem was proved in
  3029 (theory_of_thm);
  3030 
  3031 * Bugs fixed in the inductive definition and datatype packages;
  3032 
  3033 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  3034 and HOL_dup_cs obsolete;
  3035 
  3036 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  3037 have been removed;
  3038 
  3039 * Simpler definition of function space in ZF;
  3040 
  3041 * new results about cardinal and ordinal arithmetic in ZF;
  3042 
  3043 * 'subtype' facility in HOL for introducing new types as subsets of existing
  3044 types;
  3045 
  3046 
  3047 $Id$