NEWS
author kleing
Fri Apr 29 11:40:29 2005 +0200 (2005-04-29)
changeset 15883 abff581e1d83
parent 15852 4f1a78454452
child 15931 8d2fdcc558d1
permissions -rw-r--r--
new thms_containing that searches for patterns instead of constants
(by Rafal Kolanski, NICTA)
     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 antiquotations @{lhs thm} and @{rhs thm} printing the lhs/rhs of
   208   definitions, equations, inequations etc.
   209 
   210 * Antiquotations now provide the option 'locale=NAME' to specify an
   211   alternative context used for evaluating and printing the subsequent
   212   argument, as in @{thm [locale=LC] fold_commute}, for example.
   213 
   214 * Commands 'display_drafts' and 'print_drafts' perform simple output
   215   of raw sources.  Only those symbols that do not require additional
   216   LaTeX packages (depending on comments in isabellesym.sty) are
   217   displayed properly, everything else is left verbatim.  We use
   218   isatool display and isatool print as front ends; these are subject
   219   to the DVI/PDF_VIEWER and PRINT_COMMAND settings, respectively.
   220 
   221 * Proof scripts as well as some other commands such as ML or
   222   parse/print_translation can now be hidden in the document.  Hiding
   223   is enabled by default, and can be disabled either via the option '-H
   224   false' of isatool usedir or by resetting the reference variable
   225   IsarOutput.hide_commands. Additional commands to be hidden may be
   226   declared using IsarOutput.add_hidden_commands.
   227 
   228 
   229 *** HOL ***
   230 
   231 * Datatype induction via method `induct' now preserves the name of the
   232   induction variable. For example, when proving P(xs::'a list) by induction
   233   on xs, the induction step is now P(xs) ==> P(a#xs) rather than
   234   P(list) ==> P(a#list) as previously.
   235 
   236 * HOL/record: reimplementation of records. Improved scalability for
   237   records with many fields, avoiding performance problems for type
   238   inference. Records are no longer composed of nested field types, but
   239   of nested extension types. Therefore the record type only grows
   240   linear in the number of extensions and not in the number of fields.
   241   The top-level (users) view on records is preserved.  Potential
   242   INCOMPATIBILITY only in strange cases, where the theory depends on
   243   the old record representation. The type generated for a record is
   244   called <record_name>_ext_type.
   245 
   246 * HOL/record: Reference record_quick_and_dirty_sensitive can be
   247   enabled to skip the proofs triggered by a record definition or a
   248   simproc (if quick_and_dirty is enabled). Definitions of large
   249   records can take quite long.
   250 
   251 * HOL/record: "record_upd_simproc" for simplification of multiple
   252   record updates enabled by default.  Moreover, trivial updates are
   253   also removed: r(|x := x r|) = r.  INCOMPATIBILITY: old proofs break
   254   occasionally, since simplification is more powerful by default.
   255 
   256 * HOL: symbolic syntax of Hilbert Choice Operator is now as follows:
   257 
   258   syntax (epsilon)
   259     "_Eps" :: "[pttrn, bool] => 'a"    ("(3\<some>_./ _)" [0, 10] 10)
   260 
   261   The symbol \<some> is displayed as the alternative epsilon of LaTeX
   262   and x-symbol; use option '-m epsilon' to get it actually printed.
   263   Moreover, the mathematically important symbolic identifier
   264   \<epsilon> becomes available as variable, constant etc.
   265 
   266 * HOL: "x > y" abbreviates "y < x" and "x >= y" abbreviates "y <= x".
   267   Similarly for all quantifiers: "ALL x > y" etc.
   268   The x-symbol for >= is \<ge>.
   269 
   270 * HOL/Set: "{x:A. P}" abbreviates "{x. x:A & P}"
   271            (and similarly for "\<in>" instead of ":")
   272 
   273 * HOL/SetInterval: The syntax for open intervals has changed:
   274 
   275   Old         New
   276   {..n(}   -> {..<n}
   277   {)n..}   -> {n<..}
   278   {m..n(}  -> {m..<n}
   279   {)m..n}  -> {m<..n}
   280   {)m..n(} -> {m<..<n}
   281 
   282   The old syntax is still supported but will disappear in the future.
   283   For conversion use the following emacs search and replace patterns:
   284 
   285   {)\([^\.]*\)\.\.  ->  {\1<\.\.}
   286   \.\.\([^(}]*\)(}  ->  \.\.<\1}
   287 
   288   They are not perfect but work quite well.
   289 
   290 * HOL: The syntax for 'setsum', summation over finite sets, has changed:
   291 
   292   The syntax for 'setsum (%x. e) A' used to be '\<Sum>x:A. e'
   293   and is now either 'SUM x:A. e' or '\<Sum>x\<in>A. e'.
   294 
   295   There is new syntax for summation over finite sets:
   296 
   297   '\<Sum>x | P. e'    is the same as  'setsum (%x. e) {x. P}'
   298   '\<Sum>x=a..b. e'   is the same as  'setsum (%x. e) {a..b}'
   299   '\<Sum>x=a..<b. e'  is the same as  'setsum (%x. e) {a..<b}'
   300   '\<Sum>x<k. e'      is the same as  'setsum (%x. e) {..<k}'
   301 
   302   Function 'Summation' over nat is gone, its syntax '\<Sum>i<k. e'
   303   now translates into 'setsum' as above.
   304 
   305 * HOL: Finite set induction: In Isar proofs, the insert case is now
   306   "case (insert x F)" instead of the old counterintuitive "case (insert F x)".
   307 
   308 * HOL/Simplifier:
   309 
   310   - Is now set up to reason about transitivity chains involving "trancl"
   311   (r^+) and "rtrancl" (r^*) by setting up tactics provided by
   312   Provers/trancl.ML as additional solvers.  INCOMPATIBILITY: old proofs break
   313   occasionally as simplification may now solve more goals than previously.
   314 
   315   - Converts x <= y into x = y if assumption y <= x is present.  Works for
   316   all partial orders (class "order"), in particular numbers and sets. For
   317   linear orders (e.g. numbers) it treats ~ x < y just like y <= x.
   318 
   319   - Simproc for "let x = a in f x"
   320   If a is a free or bound variable or a constant then the let is unfolded.
   321   Otherwise first a is simplified to a', and then f a' is simplified to
   322   g. If possible we abstract a' from g arriving at "let x = a' in g' x",
   323   otherwise we unfold the let and arrive at g. The simproc can be 
   324   enabled/disabled by the reference use_let_simproc. Potential
   325   INCOMPATIBILITY since simplification is more powerful by default.
   326 
   327 * HOL: The 'refute' command has been extended to support a much larger
   328   fragment of HOL, including axiomatic type classes, constdefs and typedefs,
   329   inductive datatypes and recursion.
   330 
   331 
   332 *** HOLCF ***
   333 
   334 * HOLCF: discontinued special version of 'constdefs' (which used to
   335   support continuous functions) in favor of the general Pure one with
   336   full type-inference.
   337 
   338 
   339 *** ZF ***
   340 
   341 * ZF/ex/{Group,Ring}: examples in abstract algebra, including the
   342   First Isomorphism Theorem (on quotienting by the kernel of a
   343   homomorphism).
   344 
   345 * ZF/Simplifier: install second copy of type solver that actually
   346   makes use of TC rules declared to Isar proof contexts (or locales);
   347   the old version is still required for ML proof scripts.
   348 
   349 
   350 *** System ***
   351 
   352 * Allow symlinks to all proper Isabelle executables (Isabelle,
   353   isabelle, isatool etc.).
   354 
   355 * isabelle-process: Poly/ML no longer needs Perl to run an interactive
   356   session.
   357 
   358 * ISABELLE_DOC_FORMAT setting specifies preferred document format (for
   359   isatool doc, isatool mkdir, display_drafts etc.).
   360 
   361 * isatool usedir: option -f allows specification of the ML file to be
   362   used by Isabelle; default is ROOT.ML.
   363 
   364 * HOL: isatool dimacs2hol converts files in DIMACS CNF format
   365   (containing Boolean satisfiability problems) into Isabelle/HOL
   366   theories.
   367 
   368 
   369 *** ML ***
   370 
   371 * Pure: output via the Isabelle channels of writeln/warning/error
   372   etc. is now passed through Output.output, with a hook for arbitrary
   373   transformations depending on the print_mode (cf. Output.add_mode --
   374   the first active mode that provides a output function wins).
   375   Already formatted output may be embedded into further text via
   376   Output.raw; the result of Pretty.string_of/str_of and derived
   377   functions (string_of_term/cterm/thm etc.) is already marked raw to
   378   accommodate easy composition of diagnostic messages etc.
   379   Programmers rarely need to care about Output.output or Output.raw at
   380   all, with some notable exceptions: Output.output is required when
   381   bypassing the standard channels (writeln etc.), or in token
   382   translations to produce properly formatted results; Output.raw is
   383   required when capturing already output material that will eventually
   384   be presented to the user a second time.  For the default print mode,
   385   both Output.output and Output.raw have no effect.
   386 
   387 * Provers: Simplifier and Classical Reasoner now support proof context
   388   dependent plug-ins (simprocs, solvers, wrappers etc.).  These extra
   389   components are stored in the theory and patched into the
   390   simpset/claset when used in an Isar proof context.  Context
   391   dependent components are maintained by the following theory
   392   operations:
   393 
   394     Simplifier.add_context_simprocs
   395     Simplifier.del_context_simprocs
   396     Simplifier.set_context_subgoaler
   397     Simplifier.reset_context_subgoaler
   398     Simplifier.add_context_looper
   399     Simplifier.del_context_looper
   400     Simplifier.add_context_unsafe_solver
   401     Simplifier.add_context_safe_solver
   402 
   403     Classical.add_context_safe_wrapper
   404     Classical.del_context_safe_wrapper
   405     Classical.add_context_unsafe_wrapper
   406     Classical.del_context_unsafe_wrapper
   407 
   408   IMPORTANT NOTE: proof tools (methods etc.) need to use
   409   local_simpset_of and local_claset_of to instead of the primitive
   410   Simplifier.get_local_simpset and Classical.get_local_claset,
   411   respectively, in order to see the context dependent fields!
   412 
   413 
   414 
   415 New in Isabelle2004 (April 2004)
   416 --------------------------------
   417 
   418 *** General ***
   419 
   420 * Provers/order.ML:  new efficient reasoner for partial and linear orders.
   421   Replaces linorder.ML.
   422 
   423 * Pure: Greek letters (except small lambda, \<lambda>), as well as Gothic
   424   (\<aa>...\<zz>\<AA>...\<ZZ>), calligraphic (\<A>...\<Z>), and Euler
   425   (\<a>...\<z>), are now considered normal letters, and can therefore
   426   be used anywhere where an ASCII letter (a...zA...Z) has until
   427   now. COMPATIBILITY: This obviously changes the parsing of some
   428   terms, especially where a symbol has been used as a binder, say
   429   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed
   430   as an identifier.  Fix it by inserting a space around former
   431   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in
   432   existing theory and ML files.
   433 
   434 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.
   435 
   436 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now
   437   allowed in identifiers. Similar to Greek letters \<^isub> is now considered
   438   a normal (but invisible) letter. For multiple letter subscripts repeat
   439   \<^isub> like this: x\<^isub>1\<^isub>2.
   440 
   441 * Pure: There are now sub-/superscripts that can span more than one
   442   character. Text between \<^bsub> and \<^esub> is set in subscript in
   443   ProofGeneral and LaTeX, text between \<^bsup> and \<^esup> in
   444   superscript. The new control characters are not identifier parts.
   445 
   446 * Pure: Control-symbols of the form \<^raw:...> will literally print the
   447   content of "..." to the latex file instead of \isacntrl... . The "..."
   448   may consist of any printable characters excluding the end bracket >.
   449 
   450 * Pure: Using new Isar command "finalconsts" (or the ML functions
   451   Theory.add_finals or Theory.add_finals_i) it is now possible to
   452   declare constants "final", which prevents their being given a definition
   453   later.  It is useful for constants whose behaviour is fixed axiomatically
   454   rather than definitionally, such as the meta-logic connectives.
   455 
   456 * Pure: 'instance' now handles general arities with general sorts
   457   (i.e. intersections of classes),
   458 
   459 * Presentation: generated HTML now uses a CSS style sheet to make layout
   460   (somewhat) independent of content. It is copied from lib/html/isabelle.css.
   461   It can be changed to alter the colors/layout of generated pages.
   462 
   463 
   464 *** Isar ***
   465 
   466 * Tactic emulation methods rule_tac, erule_tac, drule_tac, frule_tac,
   467   cut_tac, subgoal_tac and thin_tac:
   468   - Now understand static (Isar) contexts.  As a consequence, users of Isar
   469     locales are no longer forced to write Isar proof scripts.
   470     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
   471     emulations.
   472   - INCOMPATIBILITY: names of variables to be instantiated may no
   473     longer be enclosed in quotes.  Instead, precede variable name with `?'.
   474     This is consistent with the instantiation attribute "where".
   475 
   476 * Attributes "where" and "of":
   477   - Now take type variables of instantiated theorem into account when reading
   478     the instantiation string.  This fixes a bug that caused instantiated
   479     theorems to have too special types in some circumstances.
   480   - "where" permits explicit instantiations of type variables.
   481 
   482 * Calculation commands "moreover" and "also" no longer interfere with
   483   current facts ("this"), admitting arbitrary combinations with "then"
   484   and derived forms.
   485 
   486 * Locales:
   487   - Goal statements involving the context element "includes" no longer
   488     generate theorems with internal delta predicates (those ending on
   489     "_axioms") in the premise.
   490     Resolve particular premise with <locale>.intro to obtain old form.
   491   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
   492     specification and "includes" elements in goal statement.
   493   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
   494     [intro?] and [elim?] (respectively) by default.
   495   - Experimental command for instantiation of locales in proof contexts:
   496         instantiate <label>[<attrs>]: <loc>
   497     Instantiates locale <loc> and adds all its theorems to the current context
   498     taking into account their attributes.  Label and attrs are optional
   499     modifiers, like in theorem declarations.  If present, names of
   500     instantiated theorems are qualified with <label>, and the attributes
   501     <attrs> are applied after any attributes these theorems might have already.
   502       If the locale has assumptions, a chained fact of the form
   503     "<loc> t1 ... tn" is expected from which instantiations of the parameters
   504     are derived.  The command does not support old-style locales declared
   505     with "locale (open)".
   506       A few (very simple) examples can be found in FOL/ex/LocaleInst.thy.
   507 
   508 * HOL: Tactic emulation methods induct_tac and case_tac understand static
   509   (Isar) contexts.
   510 
   511 
   512 *** HOL ***
   513 
   514 * Proof import: new image HOL4 contains the imported library from
   515   the HOL4 system with about 2500 theorems. It is imported by
   516   replaying proof terms produced by HOL4 in Isabelle. The HOL4 image
   517   can be used like any other Isabelle image.  See
   518   HOL/Import/HOL/README for more information.
   519 
   520 * Simplifier:
   521   - Much improved handling of linear and partial orders.
   522     Reasoners for linear and partial orders are set up for type classes
   523     "linorder" and "order" respectively, and are added to the default simpset
   524     as solvers.  This means that the simplifier can build transitivity chains
   525     to solve goals from the assumptions.
   526   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications
   527     of blast or auto after simplification become unnecessary because the goal
   528     is solved by simplification already.
   529 
   530 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws,
   531     all proved in axiomatic type classes for semirings, rings and fields.
   532 
   533 * Numerics:
   534   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are
   535     now formalized using the Ring_and_Field theory mentioned above.
   536   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently
   537     than before, because now they are set up once in a generic manner.
   538   - INCOMPATIBILITY: many type-specific arithmetic laws have gone.
   539     Look for the general versions in Ring_and_Field (and Power if they concern
   540     exponentiation).
   541 
   542 * Type "rat" of the rational numbers is now available in HOL-Complex.
   543 
   544 * Records:
   545   - Record types are now by default printed with their type abbreviation
   546     instead of the list of all field types. This can be configured via
   547     the reference "print_record_type_abbr".
   548   - Simproc "record_upd_simproc" for simplification of multiple updates added
   549     (not enabled by default).
   550   - Simproc "record_ex_sel_eq_simproc" to simplify EX x. sel r = x resp.
   551     EX x. x = sel r to True (not enabled by default).
   552   - Tactic "record_split_simp_tac" to split and simplify records added.
   553 
   554 * 'specification' command added, allowing for definition by
   555   specification.  There is also an 'ax_specification' command that
   556   introduces the new constants axiomatically.
   557 
   558 * arith(_tac) is now able to generate counterexamples for reals as well.
   559 
   560 * HOL-Algebra: new locale "ring" for non-commutative rings.
   561 
   562 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
   563   definitions, thanks to Sava Krsti\'{c} and John Matthews.
   564 
   565 * HOL-Matrix: a first theory for matrices in HOL with an application of
   566   matrix theory to linear programming.
   567 
   568 * Unions and Intersections:
   569   The latex output syntax of UN and INT has been changed
   570   from "\Union x \in A. B" to "\Union_{x \in A} B"
   571   i.e. the index formulae has become a subscript.
   572   Similarly for "\Union x. B", and for \Inter instead of \Union.
   573 
   574 * Unions and Intersections over Intervals:
   575   There is new short syntax "UN i<=n. A" for "UN i:{0..n}. A". There is
   576   also an x-symbol version with subscripts "\<Union>\<^bsub>i <= n\<^esub>. A"
   577   like in normal math, and corresponding versions for < and for intersection.
   578 
   579 * HOL/List: Ordering "lexico" is renamed "lenlex" and the standard
   580   lexicographic dictonary ordering has been added as "lexord".
   581 
   582 * ML: the legacy theory structures Int and List have been removed. They had
   583   conflicted with ML Basis Library structures having the same names.
   584 
   585 * 'refute' command added to search for (finite) countermodels.  Only works
   586   for a fragment of HOL.  The installation of an external SAT solver is
   587   highly recommended.  See "HOL/Refute.thy" for details.
   588 
   589 * 'quickcheck' command: Allows to find counterexamples by evaluating
   590   formulae under an assignment of free variables to random values.
   591   In contrast to 'refute', it can deal with inductive datatypes,
   592   but cannot handle quantifiers. See "HOL/ex/Quickcheck_Examples.thy"
   593   for examples.
   594 
   595 
   596 *** HOLCF ***
   597 
   598 * Streams now come with concatenation and are part of the HOLCF image
   599 
   600 
   601 
   602 New in Isabelle2003 (May 2003)
   603 ------------------------------
   604 
   605 *** General ***
   606 
   607 * Provers/simplifier:
   608 
   609   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   610     Assumptions are now subject to complete mutual simplification,
   611     not just from left to right. The simplifier now preserves
   612     the order of assumptions.
   613 
   614     Potential INCOMPATIBILITY:
   615 
   616     -- simp sometimes diverges where the old version did
   617        not, e.g. invoking simp on the goal
   618 
   619         [| P (f x); y = x; f x = f y |] ==> Q
   620 
   621        now gives rise to the infinite reduction sequence
   622 
   623         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   624 
   625        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   626        kind of problem.
   627 
   628     -- Tactics combining classical reasoner and simplification (such as auto)
   629        are also affected by this change, because many of them rely on
   630        simp. They may sometimes diverge as well or yield a different numbers
   631        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   632        in case of problems. Sometimes subsequent calls to the classical
   633        reasoner will fail because a preceeding call to the simplifier too
   634        eagerly simplified the goal, e.g. deleted redundant premises.
   635 
   636   - The simplifier trace now shows the names of the applied rewrite rules
   637 
   638   - You can limit the number of recursive invocations of the simplifier
   639     during conditional rewriting (where the simplifie tries to solve the
   640     conditions before applying the rewrite rule):
   641     ML "simp_depth_limit := n"
   642     where n is an integer. Thus you can force termination where previously
   643     the simplifier would diverge.
   644 
   645   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   646 
   647   - No longer aborts on failed congruence proof.  Instead, the
   648     congruence is ignored.
   649 
   650 * Pure: New generic framework for extracting programs from constructive
   651   proofs. See HOL/Extraction.thy for an example instantiation, as well
   652   as HOL/Extraction for some case studies.
   653 
   654 * Pure: The main goal of the proof state is no longer shown by default, only
   655 the subgoals. This behaviour is controlled by a new flag.
   656    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   657 (ML: Proof.show_main_goal).
   658 
   659 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   660 rules whose conclusion matches subgoal 1:
   661       PG menu: Isabelle/Isar -> Show me -> matching rules
   662 The rules are ordered by how closely they match the subgoal.
   663 In particular, rules that solve a subgoal outright are displayed first
   664 (or rather last, the way they are printed).
   665 (ML: ProofGeneral.print_intros())
   666 
   667 * Pure: New flag trace_unify_fail causes unification to print
   668 diagnostic information (PG: in trace buffer) when it fails. This is
   669 useful for figuring out why single step proofs like rule, erule or
   670 assumption failed.
   671 
   672 * Pure: Locale specifications now produce predicate definitions
   673 according to the body of text (covering assumptions modulo local
   674 definitions); predicate "loc_axioms" covers newly introduced text,
   675 while "loc" is cumulative wrt. all included locale expressions; the
   676 latter view is presented only on export into the global theory
   677 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   678 on the old view without predicates;
   679 
   680 * Pure: predefined locales "var" and "struct" are useful for sharing
   681 parameters (as in CASL, for example); just specify something like
   682 ``var x + var y + struct M'' as import;
   683 
   684 * Pure: improved thms_containing: proper indexing of facts instead of
   685 raw theorems; check validity of results wrt. current name space;
   686 include local facts of proof configuration (also covers active
   687 locales), cover fixed variables in index; may use "_" in term
   688 specification; an optional limit for the number of printed facts may
   689 be given (the default is 40);
   690 
   691 * Pure: disallow duplicate fact bindings within new-style theory files
   692 (batch-mode only);
   693 
   694 * Provers: improved induct method: assumptions introduced by case
   695 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   696 the goal statement); "foo" still refers to all facts collectively;
   697 
   698 * Provers: the function blast.overloaded has been removed: all constants
   699 are regarded as potentially overloaded, which improves robustness in exchange
   700 for slight decrease in efficiency;
   701 
   702 * Provers/linorder: New generic prover for transitivity reasoning over
   703 linear orders.  Note: this prover is not efficient!
   704 
   705 * Isar: preview of problems to finish 'show' now produce an error
   706 rather than just a warning (in interactive mode);
   707 
   708 
   709 *** HOL ***
   710 
   711 * arith(_tac)
   712 
   713  - Produces a counter example if it cannot prove a goal.
   714    Note that the counter example may be spurious if the goal is not a formula
   715    of quantifier-free linear arithmetic.
   716    In ProofGeneral the counter example appears in the trace buffer.
   717 
   718  - Knows about div k and mod k where k is a numeral of type nat or int.
   719 
   720  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   721    linear arithmetic fails. This takes account of quantifiers and divisibility.
   722    Presburger arithmetic can also be called explicitly via presburger(_tac).
   723 
   724 * simp's arithmetic capabilities have been enhanced a bit: it now
   725 takes ~= in premises into account (by performing a case split);
   726 
   727 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   728 are distributed over a sum of terms;
   729 
   730 * New tactic "trans_tac" and method "trans" instantiate
   731 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   732 "<=", "<" and "=").
   733 
   734 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main
   735 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   736 
   737 * 'typedef' command has new option "open" to suppress the set
   738 definition;
   739 
   740 * functions Min and Max on finite sets have been introduced (theory
   741 Finite_Set);
   742 
   743 * attribute [symmetric] now works for relations as well; it turns
   744 (x,y) : R^-1 into (y,x) : R, and vice versa;
   745 
   746 * induct over a !!-quantified statement (say !!x1..xn):
   747   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   748 
   749 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   750 %x. None. Warning: empty_def now refers to the previously hidden definition
   751 of the empty set.
   752 
   753 * Algebra: formalization of classical algebra.  Intended as base for
   754 any algebraic development in Isabelle.  Currently covers group theory
   755 (up to Sylow's theorem) and ring theory (Universal Property of
   756 Univariate Polynomials).  Contributions welcome;
   757 
   758 * GroupTheory: deleted, since its material has been moved to Algebra;
   759 
   760 * Complex: new directory of the complex numbers with numeric constants,
   761 nonstandard complex numbers, and some complex analysis, standard and
   762 nonstandard (Jacques Fleuriot);
   763 
   764 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   765 
   766 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques
   767 Fleuriot);
   768 
   769 * Real/HahnBanach: updated and adapted to locales;
   770 
   771 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   772 Gray and Kramer);
   773 
   774 * UNITY: added the Meier-Sanders theory of progress sets;
   775 
   776 * MicroJava: bytecode verifier and lightweight bytecode verifier
   777 as abstract algorithms, instantiated to the JVM;
   778 
   779 * Bali: Java source language formalization. Type system, operational
   780 semantics, axiomatic semantics. Supported language features:
   781 classes, interfaces, objects,virtual methods, static methods,
   782 static/instance fields, arrays, access modifiers, definite
   783 assignment, exceptions.
   784 
   785 
   786 *** ZF ***
   787 
   788 * ZF/Constructible: consistency proof for AC (Gdel's constructible
   789 universe, etc.);
   790 
   791 * Main ZF: virtually all theories converted to new-style format;
   792 
   793 
   794 *** ML ***
   795 
   796 * Pure: Tactic.prove provides sane interface for internal proofs;
   797 omits the infamous "standard" operation, so this is more appropriate
   798 than prove_goalw_cterm in many situations (e.g. in simprocs);
   799 
   800 * Pure: improved error reporting of simprocs;
   801 
   802 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   803 up simprocs;
   804 
   805 
   806 *** Document preparation ***
   807 
   808 * uses \par instead of \\ for line breaks in theory text. This may
   809 shift some page breaks in large documents. To get the old behaviour
   810 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   811 
   812 * minimized dependencies of isabelle.sty and isabellesym.sty on
   813 other packages
   814 
   815 * \<euro> now needs package babel/greek instead of marvosym (which
   816 broke \Rightarrow)
   817 
   818 * normal size for \<zero>...\<nine> (uses \mathbf instead of
   819 textcomp package)
   820 
   821 
   822 
   823 New in Isabelle2002 (March 2002)
   824 --------------------------------
   825 
   826 *** Document preparation ***
   827 
   828 * greatly simplified document preparation setup, including more
   829 graceful interpretation of isatool usedir -i/-d/-D options, and more
   830 instructive isatool mkdir; users should basically be able to get
   831 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   832 users may run a separate document processing stage manually like this:
   833 "isatool usedir -D output HOL Test && isatool document Test/output";
   834 
   835 * theory dependency graph may now be incorporated into documents;
   836 isatool usedir -g true will produce session_graph.eps/.pdf for use
   837 with \includegraphics of LaTeX;
   838 
   839 * proper spacing of consecutive markup elements, especially text
   840 blocks after section headings;
   841 
   842 * support bold style (for single symbols only), input syntax is like
   843 this: "\<^bold>\<alpha>" or "\<^bold>A";
   844 
   845 * \<bullet> is now output as bold \cdot by default, which looks much
   846 better in printed text;
   847 
   848 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   849 note that these symbols are currently unavailable in Proof General /
   850 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   851 
   852 * isatool latex no longer depends on changed TEXINPUTS, instead
   853 isatool document copies the Isabelle style files to the target
   854 location;
   855 
   856 
   857 *** Isar ***
   858 
   859 * Pure/Provers: improved proof by cases and induction;
   860   - 'case' command admits impromptu naming of parameters (such as
   861     "case (Suc n)");
   862   - 'induct' method divinates rule instantiation from the inductive
   863     claim; no longer requires excessive ?P bindings for proper
   864     instantiation of cases;
   865   - 'induct' method properly enumerates all possibilities of set/type
   866     rules; as a consequence facts may be also passed through *type*
   867     rules without further ado;
   868   - 'induct' method now derives symbolic cases from the *rulified*
   869     rule (before it used to rulify cases stemming from the internal
   870     atomized version); this means that the context of a non-atomic
   871     statement becomes is included in the hypothesis, avoiding the
   872     slightly cumbersome show "PROP ?case" form;
   873   - 'induct' may now use elim-style induction rules without chaining
   874     facts, using ``missing'' premises from the goal state; this allows
   875     rules stemming from inductive sets to be applied in unstructured
   876     scripts, while still benefitting from proper handling of non-atomic
   877     statements; NB: major inductive premises need to be put first, all
   878     the rest of the goal is passed through the induction;
   879   - 'induct' proper support for mutual induction involving non-atomic
   880     rule statements (uses the new concept of simultaneous goals, see
   881     below);
   882   - append all possible rule selections, but only use the first
   883     success (no backtracking);
   884   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   885   - undeclared rule case names default to numbers 1, 2, 3, ...;
   886   - added 'print_induct_rules' (covered by help item in recent Proof
   887     General versions);
   888   - moved induct/cases attributes to Pure, methods to Provers;
   889   - generic method setup instantiated for FOL and HOL;
   890 
   891 * Pure: support multiple simultaneous goal statements, for example
   892 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   893 meta-level mechanism, this acts as if several individual goals had
   894 been stated separately; in particular common proof methods need to be
   895 repeated in order to cover all claims; note that a single elimination
   896 step is *not* sufficient to establish the two conjunctions, so this
   897 fails:
   898 
   899   assume "A & B" then have A and B ..   (*".." fails*)
   900 
   901 better use "obtain" in situations as above; alternative refer to
   902 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   903 
   904 * Pure: proper integration with ``locales''; unlike the original
   905 version by Florian Kammller, Isar locales package high-level proof
   906 contexts rather than raw logical ones (e.g. we admit to include
   907 attributes everywhere); operations on locales include merge and
   908 rename; support for implicit arguments (``structures''); simultaneous
   909 type-inference over imports and text; see also HOL/ex/Locales.thy for
   910 some examples;
   911 
   912 * Pure: the following commands have been ``localized'', supporting a
   913 target locale specification "(in name)": 'lemma', 'theorem',
   914 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   915 stored both within the locale and at the theory level (exported and
   916 qualified by the locale name);
   917 
   918 * Pure: theory goals may now be specified in ``long'' form, with
   919 ad-hoc contexts consisting of arbitrary locale elements. for example
   920 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   921 definitions may be given, too); the result is a meta-level rule with
   922 the context elements being discharged in the obvious way;
   923 
   924 * Pure: new proof command 'using' allows to augment currently used
   925 facts after a goal statement ('using' is syntactically analogous to
   926 'apply', but acts on the goal's facts only); this allows chained facts
   927 to be separated into parts given before and after a claim, as in
   928 ``from a and b have C using d and e <proof>'';
   929 
   930 * Pure: renamed "antecedent" case to "rule_context";
   931 
   932 * Pure: new 'judgment' command records explicit information about the
   933 object-logic embedding (used by several tools internally); no longer
   934 use hard-wired "Trueprop";
   935 
   936 * Pure: added 'corollary' command;
   937 
   938 * Pure: fixed 'token_translation' command;
   939 
   940 * Pure: removed obsolete 'exported' attribute;
   941 
   942 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   943 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   944 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   945 
   946 * Pure: method 'atomize' presents local goal premises as object-level
   947 statements (atomic meta-level propositions); setup controlled via
   948 rewrite rules declarations of 'atomize' attribute; example
   949 application: 'induct' method with proper rule statements in improper
   950 proof *scripts*;
   951 
   952 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   953 now consider the syntactic context of assumptions, giving a better
   954 chance to get type-inference of the arguments right (this is
   955 especially important for locales);
   956 
   957 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   958 mode;
   959 
   960 * Pure/obtain: the formal conclusion "thesis", being marked as
   961 ``internal'', may no longer be reference directly in the text;
   962 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   963 situations;
   964 
   965 * Pure: generic 'sym' attribute which declares a rule both as pure
   966 'elim?' and for the 'symmetric' operation;
   967 
   968 * Pure: marginal comments ``--'' may now occur just anywhere in the
   969 text; the fixed correlation with particular command syntax has been
   970 discontinued;
   971 
   972 * Pure: new method 'rules' is particularly well-suited for proof
   973 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   974 but often produces more compact proof terms with less detours;
   975 
   976 * Pure/Provers/classical: simplified integration with pure rule
   977 attributes and methods; the classical "intro?/elim?/dest?"
   978 declarations coincide with the pure ones; the "rule" method no longer
   979 includes classically swapped intros; "intro" and "elim" methods no
   980 longer pick rules from the context; also got rid of ML declarations
   981 AddXIs/AddXEs/AddXDs; all of this has some potential for
   982 INCOMPATIBILITY;
   983 
   984 * Provers/classical: attribute 'swapped' produces classical inversions
   985 of introduction rules;
   986 
   987 * Provers/simplifier: 'simplified' attribute may refer to explicit
   988 rules instead of full simplifier context; 'iff' attribute handles
   989 conditional rules;
   990 
   991 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   992 
   993 * HOL: 'recdef' now fails on unfinished automated proofs, use
   994 "(permissive)" option to recover old behavior;
   995 
   996 * HOL: 'inductive' no longer features separate (collective) attributes
   997 for 'intros' (was found too confusing);
   998 
   999 * HOL: properly declared induction rules less_induct and
  1000 wf_induct_rule;
  1001 
  1002 
  1003 *** HOL ***
  1004 
  1005 * HOL: moved over to sane numeral syntax; the new policy is as
  1006 follows:
  1007 
  1008   - 0 and 1 are polymorphic constants, which are defined on any
  1009   numeric type (nat, int, real etc.);
  1010 
  1011   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
  1012   binary representation internally;
  1013 
  1014   - type nat has special constructor Suc, and generally prefers Suc 0
  1015   over 1::nat and Suc (Suc 0) over 2::nat;
  1016 
  1017 This change may cause significant problems of INCOMPATIBILITY; here
  1018 are some hints on converting existing sources:
  1019 
  1020   - due to the new "num" token, "-0" and "-1" etc. are now atomic
  1021   entities, so expressions involving "-" (unary or binary minus) need
  1022   to be spaced properly;
  1023 
  1024   - existing occurrences of "1" may need to be constraint "1::nat" or
  1025   even replaced by Suc 0; similar for old "2";
  1026 
  1027   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
  1028 
  1029   - remove all special provisions on numerals in proofs;
  1030 
  1031 * HOL: simp rules nat_number expand numerals on nat to Suc/0
  1032 representation (depends on bin_arith_simps in the default context);
  1033 
  1034 * HOL: symbolic syntax for x^2 (numeral 2);
  1035 
  1036 * HOL: the class of all HOL types is now called "type" rather than
  1037 "term"; INCOMPATIBILITY, need to adapt references to this type class
  1038 in axclass/classes, instance/arities, and (usually rare) occurrences
  1039 in typings (of consts etc.); internally the class is called
  1040 "HOL.type", ML programs should refer to HOLogic.typeS;
  1041 
  1042 * HOL/record package improvements:
  1043   - new derived operations "fields" to build a partial record section,
  1044     "extend" to promote a fixed record to a record scheme, and
  1045     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
  1046     declared as simp by default;
  1047   - shared operations ("more", "fields", etc.) now need to be always
  1048     qualified) --- potential INCOMPATIBILITY;
  1049   - removed "make_scheme" operations (use "make" with "extend") --
  1050     INCOMPATIBILITY;
  1051   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
  1052   - provides cases/induct rules for use with corresponding Isar
  1053     methods (for concrete records, record schemes, concrete more
  1054     parts, and schematic more parts -- in that order);
  1055   - internal definitions directly based on a light-weight abstract
  1056     theory of product types over typedef rather than datatype;
  1057 
  1058 * HOL: generic code generator for generating executable ML code from
  1059 specifications; specific support for HOL constructs such as inductive
  1060 datatypes and sets, as well as recursive functions; can be invoked
  1061 via 'generate_code' theory section;
  1062 
  1063 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
  1064 
  1065 * HOL: consolidated and renamed several theories.  In particular:
  1066         Ord.thy has been absorbed into HOL.thy
  1067         String.thy has been absorbed into List.thy
  1068 
  1069 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
  1070 (beware of argument permutation!);
  1071 
  1072 * HOL: linorder_less_split superseded by linorder_cases;
  1073 
  1074 * HOL/List: "nodups" renamed to "distinct";
  1075 
  1076 * HOL: added "The" definite description operator; move Hilbert's "Eps"
  1077 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
  1078   - Ex_def has changed, now need to use some_eq_ex
  1079 
  1080 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
  1081 in this (rare) case use:
  1082 
  1083   delSWrapper "split_all_tac"
  1084   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
  1085 
  1086 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
  1087 MAY FAIL;
  1088 
  1089 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
  1090 Isabelle's type classes, ^ on functions and relations has too general
  1091 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
  1092 necessary to attach explicit type constraints;
  1093 
  1094 * HOL/Relation: the prefix name of the infix "O" has been changed from
  1095 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
  1096 renamed accordingly (eg "compI" -> "rel_compI").
  1097 
  1098 * HOL: syntax translations now work properly with numerals and records
  1099 expressions;
  1100 
  1101 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
  1102 of "lam" -- INCOMPATIBILITY;
  1103 
  1104 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
  1105 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
  1106 renamed "Product_Type.unit";
  1107 
  1108 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
  1109 
  1110 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
  1111 the "cases" method);
  1112 
  1113 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
  1114 Florian Kammller);
  1115 
  1116 * HOL/IMP: updated and converted to new-style theory format; several
  1117 parts turned into readable document, with proper Isar proof texts and
  1118 some explanations (by Gerwin Klein);
  1119 
  1120 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
  1121 
  1122 * HOL-Hyperreal is now a logic image;
  1123 
  1124 
  1125 *** HOLCF ***
  1126 
  1127 * Isar: consts/constdefs supports mixfix syntax for continuous
  1128 operations;
  1129 
  1130 * Isar: domain package adapted to new-style theory format, e.g. see
  1131 HOLCF/ex/Dnat.thy;
  1132 
  1133 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
  1134 potential INCOMPATIBILITY; now use plain induct_tac instead of former
  1135 lift.induct_tac, always use UU instead of Undef;
  1136 
  1137 * HOLCF/IMP: updated and converted to new-style theory;
  1138 
  1139 
  1140 *** ZF ***
  1141 
  1142 * Isar: proper integration of logic-specific tools and packages,
  1143 including theory commands '(co)inductive', '(co)datatype',
  1144 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
  1145 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
  1146 
  1147 * theory Main no longer includes AC; for the Axiom of Choice, base
  1148 your theory on Main_ZFC;
  1149 
  1150 * the integer library now covers quotients and remainders, with many
  1151 laws relating division to addition, multiplication, etc.;
  1152 
  1153 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
  1154 typeless version of the formalism;
  1155 
  1156 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
  1157 format;
  1158 
  1159 * ZF/Induct: new directory for examples of inductive definitions,
  1160 including theory Multiset for multiset orderings; converted to
  1161 new-style theory format;
  1162 
  1163 * ZF: many new theorems about lists, ordinals, etc.;
  1164 
  1165 
  1166 *** General ***
  1167 
  1168 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
  1169 variable proof controls level of detail: 0 = no proofs (only oracle
  1170 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
  1171 also ref manual for further ML interfaces;
  1172 
  1173 * Pure/axclass: removed obsolete ML interface
  1174 goal_subclass/goal_arity;
  1175 
  1176 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
  1177 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
  1178 separate tokens, so expressions involving minus need to be spaced
  1179 properly;
  1180 
  1181 * Pure/syntax: support non-oriented infixes, using keyword "infix"
  1182 rather than "infixl" or "infixr";
  1183 
  1184 * Pure/syntax: concrete syntax for dummy type variables admits genuine
  1185 sort constraint specifications in type inference; e.g. "x::_::foo"
  1186 ensures that the type of "x" is of sort "foo" (but not necessarily a
  1187 type variable);
  1188 
  1189 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
  1190 control output of nested => (types); the default behavior is
  1191 "type_brackets";
  1192 
  1193 * Pure/syntax: builtin parse translation for "_constify" turns valued
  1194 tokens into AST constants;
  1195 
  1196 * Pure/syntax: prefer later declarations of translations and print
  1197 translation functions; potential INCOMPATIBILITY: need to reverse
  1198 multiple declarations for same syntax element constant;
  1199 
  1200 * Pure/show_hyps reset by default (in accordance to existing Isar
  1201 practice);
  1202 
  1203 * Provers/classical: renamed addaltern to addafter, addSaltern to
  1204 addSafter;
  1205 
  1206 * Provers/clasimp: ``iff'' declarations now handle conditional rules
  1207 as well;
  1208 
  1209 * system: tested support for MacOS X; should be able to get Isabelle +
  1210 Proof General to work in a plain Terminal after installing Poly/ML
  1211 (e.g. from the Isabelle distribution area) and GNU bash alone
  1212 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
  1213 support requires further installations, e.g. from
  1214 http://fink.sourceforge.net/);
  1215 
  1216 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
  1217 
  1218 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
  1219 of 40 MB), cf. ML_OPTIONS;
  1220 
  1221 * system: Proof General keywords specification is now part of the
  1222 Isabelle distribution (see etc/isar-keywords.el);
  1223 
  1224 * system: support for persistent Proof General sessions (refrain from
  1225 outdating all loaded theories on startup); user may create writable
  1226 logic images like this: ``isabelle -q HOL Test'';
  1227 
  1228 * system: smart selection of Isabelle process versus Isabelle
  1229 interface, accommodates case-insensitive file systems (e.g. HFS+); may
  1230 run both "isabelle" and "Isabelle" even if file names are badly
  1231 damaged (executable inspects the case of the first letter of its own
  1232 name); added separate "isabelle-process" and "isabelle-interface";
  1233 
  1234 * system: refrain from any attempt at filtering input streams; no
  1235 longer support ``8bit'' encoding of old isabelle font, instead proper
  1236 iso-latin characters may now be used; the related isatools
  1237 "symbolinput" and "nonascii" have disappeared as well;
  1238 
  1239 * system: removed old "xterm" interface (the print modes "xterm" and
  1240 "xterm_color" are still available for direct use in a suitable
  1241 terminal);
  1242 
  1243 
  1244 
  1245 New in Isabelle99-2 (February 2001)
  1246 -----------------------------------
  1247 
  1248 *** Overview of INCOMPATIBILITIES ***
  1249 
  1250 * HOL: please note that theories in the Library and elsewhere often use the
  1251 new-style (Isar) format; to refer to their theorems in an ML script you must
  1252 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
  1253 
  1254 * HOL: inductive package no longer splits induction rule aggressively,
  1255 but only as far as specified by the introductions given; the old
  1256 format may be recovered via ML function complete_split_rule or attribute
  1257 'split_rule (complete)';
  1258 
  1259 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
  1260 gfp_Tarski to gfp_unfold;
  1261 
  1262 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
  1263 
  1264 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
  1265 relation); infix "^^" has been renamed "``"; infix "``" has been
  1266 renamed "`"; "univalent" has been renamed "single_valued";
  1267 
  1268 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
  1269 operation;
  1270 
  1271 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
  1272 
  1273 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
  1274 
  1275 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
  1276 consequence, it is no longer monotonic wrt. the local goal context
  1277 (which is now passed through the inductive cases);
  1278 
  1279 * Document preparation: renamed standard symbols \<ll> to \<lless> and
  1280 \<gg> to \<ggreater>;
  1281 
  1282 
  1283 *** Document preparation ***
  1284 
  1285 * \isabellestyle{NAME} selects version of Isabelle output (currently
  1286 available: are "it" for near math-mode best-style output, "sl" for
  1287 slanted text style, and "tt" for plain type-writer; if no
  1288 \isabellestyle command is given, output is according to slanted
  1289 type-writer);
  1290 
  1291 * support sub/super scripts (for single symbols only), input syntax is
  1292 like this: "A\<^sup>*" or "A\<^sup>\<star>";
  1293 
  1294 * some more standard symbols; see Appendix A of the system manual for
  1295 the complete list of symbols defined in isabellesym.sty;
  1296 
  1297 * improved isabelle style files; more abstract symbol implementation
  1298 (should now use \isamath{...} and \isatext{...} in custom symbol
  1299 definitions);
  1300 
  1301 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
  1302 state; Note that presentation of goal states does not conform to
  1303 actual human-readable proof documents.  Please do not include goal
  1304 states into document output unless you really know what you are doing!
  1305 
  1306 * proper indentation of antiquoted output with proportional LaTeX
  1307 fonts;
  1308 
  1309 * no_document ML operator temporarily disables LaTeX document
  1310 generation;
  1311 
  1312 * isatool unsymbolize tunes sources for plain ASCII communication;
  1313 
  1314 
  1315 *** Isar ***
  1316 
  1317 * Pure: Isar now suffers initial goal statements to contain unbound
  1318 schematic variables (this does not conform to actual readable proof
  1319 documents, due to unpredictable outcome and non-compositional proof
  1320 checking); users who know what they are doing may use schematic goals
  1321 for Prolog-style synthesis of proven results;
  1322 
  1323 * Pure: assumption method (an implicit finishing) now handles actual
  1324 rules as well;
  1325 
  1326 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
  1327 initial goal, declare "that" only as Pure intro (only for single
  1328 steps); the "that" rule assumption may now be involved in implicit
  1329 finishing, thus ".." becomes a feasible for trivial obtains;
  1330 
  1331 * Pure: default proof step now includes 'intro_classes'; thus trivial
  1332 instance proofs may be performed by "..";
  1333 
  1334 * Pure: ?thesis / ?this / "..." now work for pure meta-level
  1335 statements as well;
  1336 
  1337 * Pure: more robust selection of calculational rules;
  1338 
  1339 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
  1340 rule (as well as the assumption rule);
  1341 
  1342 * Pure: 'thm_deps' command visualizes dependencies of theorems and
  1343 lemmas, using the graph browser tool;
  1344 
  1345 * Pure: predict failure of "show" in interactive mode;
  1346 
  1347 * Pure: 'thms_containing' now takes actual terms as arguments;
  1348 
  1349 * HOL: improved method 'induct' --- now handles non-atomic goals
  1350 (potential INCOMPATIBILITY); tuned error handling;
  1351 
  1352 * HOL: cases and induct rules now provide explicit hints about the
  1353 number of facts to be consumed (0 for "type" and 1 for "set" rules);
  1354 any remaining facts are inserted into the goal verbatim;
  1355 
  1356 * HOL: local contexts (aka cases) may now contain term bindings as
  1357 well; the 'cases' and 'induct' methods new provide a ?case binding for
  1358 the result to be shown in each case;
  1359 
  1360 * HOL: added 'recdef_tc' command;
  1361 
  1362 * isatool convert assists in eliminating legacy ML scripts;
  1363 
  1364 
  1365 *** HOL ***
  1366 
  1367 * HOL/Library: a collection of generic theories to be used together
  1368 with main HOL; the theory loader path already includes this directory
  1369 by default; the following existing theories have been moved here:
  1370 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
  1371 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
  1372 
  1373 * HOL/Unix: "Some aspects of Unix file-system security", a typical
  1374 modelling and verification task performed in Isabelle/HOL +
  1375 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
  1376 
  1377 * HOL/Algebra: special summation operator SUM no longer exists, it has
  1378 been replaced by setsum; infix 'assoc' now has priority 50 (like
  1379 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
  1380 'domain', this makes the theory consistent with mathematical
  1381 literature;
  1382 
  1383 * HOL basics: added overloaded operations "inverse" and "divide"
  1384 (infix "/"), syntax for generic "abs" operation, generic summation
  1385 operator \<Sum>;
  1386 
  1387 * HOL/typedef: simplified package, provide more useful rules (see also
  1388 HOL/subset.thy);
  1389 
  1390 * HOL/datatype: induction rule for arbitrarily branching datatypes is
  1391 now expressed as a proper nested rule (old-style tactic scripts may
  1392 require atomize_strip_tac to cope with non-atomic premises);
  1393 
  1394 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
  1395 to "split_conv" (old name still available for compatibility);
  1396 
  1397 * HOL: improved concrete syntax for strings (e.g. allows translation
  1398 rules with string literals);
  1399 
  1400 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
  1401  and Fleuriot's mechanization of analysis, including the transcendental
  1402  functions for the reals;
  1403 
  1404 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
  1405 
  1406 
  1407 *** CTT ***
  1408 
  1409 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
  1410 "lam" is displayed as TWO lambda-symbols
  1411 
  1412 * CTT: theory Main now available, containing everything (that is, Bool
  1413 and Arith);
  1414 
  1415 
  1416 *** General ***
  1417 
  1418 * Pure: the Simplifier has been implemented properly as a derived rule
  1419 outside of the actual kernel (at last!); the overall performance
  1420 penalty in practical applications is about 50%, while reliability of
  1421 the Isabelle inference kernel has been greatly improved;
  1422 
  1423 * print modes "brackets" and "no_brackets" control output of nested =>
  1424 (types) and ==> (props); the default behaviour is "brackets";
  1425 
  1426 * Provers: fast_tac (and friends) now handle actual object-logic rules
  1427 as assumptions as well;
  1428 
  1429 * system: support Poly/ML 4.0;
  1430 
  1431 * system: isatool install handles KDE version 1 or 2;
  1432 
  1433 
  1434 
  1435 New in Isabelle99-1 (October 2000)
  1436 ----------------------------------
  1437 
  1438 *** Overview of INCOMPATIBILITIES ***
  1439 
  1440 * HOL: simplification of natural numbers is much changed; to partly
  1441 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
  1442 issue the following ML commands:
  1443 
  1444   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
  1445   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
  1446 
  1447 * HOL: simplification no longer dives into case-expressions; this is
  1448 controlled by "t.weak_case_cong" for each datatype t;
  1449 
  1450 * HOL: nat_less_induct renamed to less_induct;
  1451 
  1452 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
  1453 fixsome to patch .thy and .ML sources automatically;
  1454 
  1455   select_equality  -> some_equality
  1456   select_eq_Ex     -> some_eq_ex
  1457   selectI2EX       -> someI2_ex
  1458   selectI2         -> someI2
  1459   selectI          -> someI
  1460   select1_equality -> some1_equality
  1461   Eps_sym_eq       -> some_sym_eq_trivial
  1462   Eps_eq           -> some_eq_trivial
  1463 
  1464 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
  1465 
  1466 * HOL: removed obsolete theorem binding expand_if (refer to split_if
  1467 instead);
  1468 
  1469 * HOL: the recursion equations generated by 'recdef' are now called
  1470 f.simps instead of f.rules;
  1471 
  1472 * HOL: qed_spec_mp now also handles bounded ALL as well;
  1473 
  1474 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  1475 sometimes be needed;
  1476 
  1477 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  1478 
  1479 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  1480 
  1481 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  1482 product is now "<*>" instead of "Times"; the lexicographic product is
  1483 now "<*lex*>" instead of "**";
  1484 
  1485 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  1486 of main HOL, but was unused); better use HOL's datatype package;
  1487 
  1488 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  1489 the old syntax may be recovered as follows:
  1490 
  1491   syntax (symbols)
  1492     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  1493       (infixl "\\<oplus>" 100)
  1494 
  1495 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1496 
  1497 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1498 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1499 internally;
  1500 
  1501 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1502 changed from A/r to A//r;
  1503 
  1504 * ZF: new treatment of arithmetic (nat & int) may break some old
  1505 proofs;
  1506 
  1507 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1508 rulify -> rule_format, elimify -> elim_format, ...);
  1509 
  1510 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1511 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1512 should have to change intro!! to intro? only); replaced "delrule" by
  1513 "rule del";
  1514 
  1515 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1516 
  1517 * Provers: strengthened force_tac by using new first_best_tac;
  1518 
  1519 * LaTeX document preparation: several changes of isabelle.sty (see
  1520 lib/texinputs);
  1521 
  1522 
  1523 *** Document preparation ***
  1524 
  1525 * formal comments (text blocks etc.) in new-style theories may now
  1526 contain antiquotations of thm/prop/term/typ/text to be presented
  1527 according to latex print mode; concrete syntax is like this:
  1528 @{term[show_types] "f(x) = a + x"};
  1529 
  1530 * isatool mkdir provides easy setup of Isabelle session directories,
  1531 including proper document sources;
  1532 
  1533 * generated LaTeX sources are now deleted after successful run
  1534 (isatool document -c); may retain a copy somewhere else via -D option
  1535 of isatool usedir;
  1536 
  1537 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1538 style files, achieving self-contained LaTeX sources and simplifying
  1539 LaTeX debugging;
  1540 
  1541 * old-style theories now produce (crude) LaTeX output as well;
  1542 
  1543 * browser info session directories are now self-contained (may be put
  1544 on WWW server seperately); improved graphs of nested sessions; removed
  1545 graph for 'all sessions';
  1546 
  1547 * several improvements in isabelle style files; \isabellestyle{it}
  1548 produces fake math mode output; \isamarkupheader is now \section by
  1549 default; see lib/texinputs/isabelle.sty etc.;
  1550 
  1551 
  1552 *** Isar ***
  1553 
  1554 * Isar/Pure: local results and corresponding term bindings are now
  1555 subject to Hindley-Milner polymorphism (similar to ML); this
  1556 accommodates incremental type-inference very nicely;
  1557 
  1558 * Isar/Pure: new derived language element 'obtain' supports
  1559 generalized existence reasoning;
  1560 
  1561 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1562 support accumulation of results, without applying any rules yet;
  1563 useful to collect intermediate results without explicit name
  1564 references, and for use with transitivity rules with more than 2
  1565 premises;
  1566 
  1567 * Isar/Pure: scalable support for case-analysis type proofs: new
  1568 'case' language element refers to local contexts symbolically, as
  1569 produced by certain proof methods; internally, case names are attached
  1570 to theorems as "tags";
  1571 
  1572 * Isar/Pure: theory command 'hide' removes declarations from
  1573 class/type/const name spaces;
  1574 
  1575 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1576 indicate potential overloading;
  1577 
  1578 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1579 
  1580 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1581 "{a,b,c}" instead of {a,b,c};
  1582 
  1583 * Isar/Pure now provides its own version of intro/elim/dest
  1584 attributes; useful for building new logics, but beware of confusion
  1585 with the version in Provers/classical;
  1586 
  1587 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1588 case name 'antecedent';
  1589 
  1590 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1591 to the current context is now done automatically);
  1592 
  1593 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1594 for definining proof methods in ML;
  1595 
  1596 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1597 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1598 most cases, one should have to change intro!! to intro? only);
  1599 replaced "delrule" by "rule del";
  1600 
  1601 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1602 'symmetric' attribute (the latter supercedes [RS sym]);
  1603 
  1604 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1605 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1606 well (including splits);
  1607 
  1608 * Isar/Provers: Simplifier and Classical methods now support all kind
  1609 of modifiers used in the past, including 'cong', 'iff', etc.
  1610 
  1611 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1612 of Simplifier and Classical reasoner);
  1613 
  1614 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1615 now support named cases; major packages (inductive, datatype, primrec,
  1616 recdef) support case names and properly name parameters;
  1617 
  1618 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1619 monotonicity conditions are extracted to be proven at end of
  1620 calculations;
  1621 
  1622 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1623 method anyway;
  1624 
  1625 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1626 split_if split_if_asm; datatype package provides theorems foo.splits =
  1627 foo.split foo.split_asm for each datatype;
  1628 
  1629 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1630 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1631 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1632 use "(cases (simplified))" method in proper proof texts);
  1633 
  1634 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1635 
  1636 * Isar: names of theorems etc. may be natural numbers as well;
  1637 
  1638 * Isar: 'pr' command: optional arguments for goals_limit and
  1639 ProofContext.prems_limit; no longer prints theory contexts, but only
  1640 proof states;
  1641 
  1642 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1643 additional print modes to be specified; e.g. "pr(latex)" will print
  1644 proof state according to the Isabelle LaTeX style;
  1645 
  1646 * Isar: improved support for emulating tactic scripts, including proof
  1647 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1648 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1649 (for HOL datatypes);
  1650 
  1651 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1652 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1653 'proof method scripts' have to be in depth-first order;
  1654 
  1655 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1656 
  1657 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1658 should instead use individual commands for printing items
  1659 (print_commands, print_methods etc.);
  1660 
  1661 * Isar: added 'nothing' --- the empty list of theorems;
  1662 
  1663 
  1664 *** HOL ***
  1665 
  1666 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1667 corresponding virtual machine and a specification of its bytecode
  1668 verifier and a lightweight bytecode verifier, including proofs of
  1669 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1670 Cornelia Pusch (see also the homepage of project Bali at
  1671 http://isabelle.in.tum.de/Bali/);
  1672 
  1673 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1674 Clemens Ballarin;
  1675 
  1676 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1677 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1678 Rasmussen;
  1679 
  1680 * HOL/Lattice: fundamental concepts of lattice theory and order
  1681 structures, including duals, properties of bounds versus algebraic
  1682 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1683 Theorem for complete lattices etc.; may also serve as a demonstration
  1684 for abstract algebraic reasoning using axiomatic type classes, and
  1685 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1686 
  1687 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1688 von Oheimb;
  1689 
  1690 * HOL/IMPP: extension of IMP with local variables and mutually
  1691 recursive procedures, by David von Oheimb;
  1692 
  1693 * HOL/Lambda: converted into new-style theory and document;
  1694 
  1695 * HOL/ex/Multiquote: example of multiple nested quotations and
  1696 anti-quotations -- basically a generalized version of de-Bruijn
  1697 representation; very useful in avoiding lifting of operations;
  1698 
  1699 * HOL/record: added general record equality rule to simpset; fixed
  1700 select-update simplification procedure to handle extended records as
  1701 well; admit "r" as field name;
  1702 
  1703 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1704 other numeric types and also as the identity of groups, rings, etc.;
  1705 
  1706 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1707 Types nat and int belong to this axclass;
  1708 
  1709 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1710    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1711    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1712   two terms #m*u and #n*u are replaced by #(m+n)*u
  1713     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1714   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1715     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1716 
  1717 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1718 powerful prover for predicate logic but knows nothing of clasets; see
  1719 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1720 
  1721 * HOL: new version of "case_tac" subsumes both boolean case split and
  1722 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1723 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1724 
  1725 * HOL: simplification no longer dives into case-expressions: only the
  1726 selector expression is simplified, but not the remaining arms; to
  1727 enable full simplification of case-expressions for datatype t, you may
  1728 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1729 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1730 
  1731 * HOL/recdef: the recursion equations generated by 'recdef' for
  1732 function 'f' are now called f.simps instead of f.rules; if all
  1733 termination conditions are proved automatically, these simplification
  1734 rules are added to the simpset, as in primrec; rules may be named
  1735 individually as well, resulting in a separate list of theorems for
  1736 each equation;
  1737 
  1738 * HOL/While is a new theory that provides a while-combinator. It
  1739 permits the definition of tail-recursive functions without the
  1740 provision of a termination measure. The latter is necessary once the
  1741 invariant proof rule for while is applied.
  1742 
  1743 * HOL: new (overloaded) notation for the set of elements below/above
  1744 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1745 
  1746 * HOL: theorems impI, allI, ballI bound as "strip";
  1747 
  1748 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1749 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1750 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1751 
  1752 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1753 
  1754 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1755 main HOL, but was unused);
  1756 
  1757 * HOL: fewer consts declared as global (e.g. have to refer to
  1758 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1759 
  1760 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1761 in case of overlap with user translations (e.g. judgements over
  1762 tuples); (note that the underlying logical represenation is still
  1763 bogus);
  1764 
  1765 
  1766 *** ZF ***
  1767 
  1768 * ZF: simplification automatically cancels common terms in arithmetic
  1769 expressions over nat and int;
  1770 
  1771 * ZF: new treatment of nat to minimize type-checking: all operators
  1772 coerce their operands to a natural number using the function natify,
  1773 making the algebraic laws unconditional;
  1774 
  1775 * ZF: as above, for int: operators coerce their operands to an integer
  1776 using the function intify;
  1777 
  1778 * ZF: the integer library now contains many of the usual laws for the
  1779 orderings, including $<=, and monotonicity laws for $+ and $*;
  1780 
  1781 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1782 simplification;
  1783 
  1784 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1785 to the simplifier and classical reasoner simultaneously;
  1786 
  1787 
  1788 *** General ***
  1789 
  1790 * Provers: blast_tac now handles actual object-logic rules as
  1791 assumptions; note that auto_tac uses blast_tac internally as well;
  1792 
  1793 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1794 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1795 
  1796 * Provers: delrules now handles destruct rules as well (no longer need
  1797 explicit make_elim);
  1798 
  1799 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1800   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1801 use instead the strong form,
  1802   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1803 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1804 from destruct-rules;
  1805 
  1806 * Provers: Simplifier.easy_setup provides a fast path to basic
  1807 Simplifier setup for new object-logics;
  1808 
  1809 * Pure: AST translation rules no longer require constant head on LHS;
  1810 
  1811 * Pure: improved name spaces: ambiguous output is qualified; support
  1812 for hiding of names;
  1813 
  1814 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1815 XSYMBOL_HOME; no longer need to do manual configuration in most
  1816 situations;
  1817 
  1818 * system: compression of ML heaps images may now be controlled via -c
  1819 option of isabelle and isatool usedir (currently only observed by
  1820 Poly/ML);
  1821 
  1822 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1823 useful for remote X11);
  1824 
  1825 * system: provide TAGS file for Isabelle sources;
  1826 
  1827 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1828 order;
  1829 
  1830 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1831 timing flag supersedes proof_timing and Toplevel.trace;
  1832 
  1833 * ML: new combinators |>> and |>>> for incremental transformations
  1834 with secondary results (e.g. certain theory extensions):
  1835 
  1836 * ML: PureThy.add_defs gets additional argument to indicate potential
  1837 overloading (usually false);
  1838 
  1839 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1840 results;
  1841 
  1842 
  1843 
  1844 New in Isabelle99 (October 1999)
  1845 --------------------------------
  1846 
  1847 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1848 
  1849 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1850 are no longer simplified.  (This allows the simplifier to unfold recursive
  1851 functional programs.)  To restore the old behaviour, declare
  1852 
  1853     Delcongs [if_weak_cong];
  1854 
  1855 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1856 complement;
  1857 
  1858 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1859 
  1860 * HOL/datatype: mutual_induct_tac no longer exists --
  1861   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1862 
  1863 * HOL/typedef: fixed type inference for representing set; type
  1864 arguments now have to occur explicitly on the rhs as type constraints;
  1865 
  1866 * ZF: The con_defs part of an inductive definition may no longer refer
  1867 to constants declared in the same theory;
  1868 
  1869 * HOL, ZF: the function mk_cases, generated by the inductive
  1870 definition package, has lost an argument.  To simplify its result, it
  1871 uses the default simpset instead of a supplied list of theorems.
  1872 
  1873 * HOL/List: the constructors of type list are now Nil and Cons;
  1874 
  1875 * Simplifier: the type of the infix ML functions
  1876         setSSolver addSSolver setSolver addSolver
  1877 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1878 for packaging solvers. A solver is created via
  1879         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1880 where the string argument is only a comment.
  1881 
  1882 
  1883 *** Proof tools ***
  1884 
  1885 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1886 decision procedure for linear arithmetic. Currently it is used for
  1887 types `nat', `int', and `real' in HOL (see below); it can, should and
  1888 will be instantiated for other types and logics as well.
  1889 
  1890 * The simplifier now accepts rewrite rules with flexible heads, eg
  1891      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1892   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1893   matching.
  1894 
  1895 
  1896 *** General ***
  1897 
  1898 * New Isabelle/Isar subsystem provides an alternative to traditional
  1899 tactical theorem proving; together with the ProofGeneral/isar user
  1900 interface it offers an interactive environment for developing human
  1901 readable proof documents (Isar == Intelligible semi-automated
  1902 reasoning); for further information see isatool doc isar-ref,
  1903 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1904 
  1905 * improved and simplified presentation of theories: better HTML markup
  1906 (including colors), graph views in several sizes; isatool usedir now
  1907 provides a proper interface for user theories (via -P option); actual
  1908 document preparation based on (PDF)LaTeX is available as well (for
  1909 new-style theories only); see isatool doc system for more information;
  1910 
  1911 * native support for Proof General, both for classic Isabelle and
  1912 Isabelle/Isar;
  1913 
  1914 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1915 using the graph browser tool;
  1916 
  1917 * Isabelle manuals now also available as PDF;
  1918 
  1919 * theory loader rewritten from scratch (may not be fully
  1920 bug-compatible); old loadpath variable has been replaced by show_path,
  1921 add_path, del_path, reset_path functions; new operations such as
  1922 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1923 isatool doc ref);
  1924 
  1925 * improved isatool install: option -k creates KDE application icon,
  1926 option -p DIR installs standalone binaries;
  1927 
  1928 * added ML_PLATFORM setting (useful for cross-platform installations);
  1929 more robust handling of platform specific ML images for SML/NJ;
  1930 
  1931 * the settings environment is now statically scoped, i.e. it is never
  1932 created again in sub-processes invoked from isabelle, isatool, or
  1933 Isabelle;
  1934 
  1935 * path element specification '~~' refers to '$ISABELLE_HOME';
  1936 
  1937 * in locales, the "assumes" and "defines" parts may be omitted if
  1938 empty;
  1939 
  1940 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1941 long arrows);
  1942 
  1943 * new print_mode "HTML";
  1944 
  1945 * new flag show_tags controls display of tags of theorems (which are
  1946 basically just comments that may be attached by some tools);
  1947 
  1948 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1949 mode and goal output format:
  1950 
  1951 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1952 244c244
  1953 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1954 ---
  1955 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1956 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1957 181c181
  1958 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1959 ---
  1960 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1961 
  1962 * function bind_thms stores lists of theorems (cf. bind_thm);
  1963 
  1964 * new shorthand tactics ftac, eatac, datac, fatac;
  1965 
  1966 * qed (and friends) now accept "" as result name; in that case the
  1967 theorem is not stored, but proper checks and presentation of the
  1968 result still apply;
  1969 
  1970 * theorem database now also indexes constants "Trueprop", "all",
  1971 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1972 
  1973 
  1974 *** HOL ***
  1975 
  1976 ** HOL arithmetic **
  1977 
  1978 * There are now decision procedures for linear arithmetic over nat and
  1979 int:
  1980 
  1981 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1982 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1983 are treated as atomic; subformulae not involving type `nat' or `int'
  1984 are ignored; quantified subformulae are ignored unless they are
  1985 positive universal or negative existential. The tactic has to be
  1986 invoked by hand and can be a little bit slow. In particular, the
  1987 running time is exponential in the number of occurrences of `min' and
  1988 `max', and `-' on `nat'.
  1989 
  1990 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1991 (negated) (in)equalities among the premises and the conclusion into
  1992 account (i.e. no compound formulae) and does not know about `min' and
  1993 `max', and `-' on `nat'. It is fast and is used automatically by the
  1994 simplifier.
  1995 
  1996 NB: At the moment, these decision procedures do not cope with mixed
  1997 nat/int formulae where the two parts interact, such as `m < n ==>
  1998 int(m) < int(n)'.
  1999 
  2000 * HOL/Numeral provides a generic theory of numerals (encoded
  2001 efficiently as bit strings); setup for types nat/int/real is in place;
  2002 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  2003 int, existing theories and proof scripts may require a few additional
  2004 type constraints;
  2005 
  2006 * integer division and remainder can now be performed on constant
  2007 arguments;
  2008 
  2009 * many properties of integer multiplication, division and remainder
  2010 are now available;
  2011 
  2012 * An interface to the Stanford Validity Checker (SVC) is available through the
  2013 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  2014 are proved automatically.  SVC must be installed separately, and its results
  2015 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  2016 invocation of the underlying oracle).  For SVC see
  2017   http://verify.stanford.edu/SVC
  2018 
  2019 * IsaMakefile: the HOL-Real target now builds an actual image;
  2020 
  2021 
  2022 ** HOL misc **
  2023 
  2024 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  2025 (in Isabelle/Isar) -- by Gertrud Bauer;
  2026 
  2027 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  2028 analysis for assembly languages with subtypes;
  2029 
  2030 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  2031 -- avoids syntactic ambiguities and treats state, transition, and
  2032 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  2033 changed syntax and (many) tactics;
  2034 
  2035 * HOL/inductive: Now also handles more general introduction rules such
  2036   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  2037   theorems are now maintained within the theory (maintained via the
  2038   "mono" attribute);
  2039 
  2040 * HOL/datatype: Now also handles arbitrarily branching datatypes
  2041   (using function types) such as
  2042 
  2043   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  2044 
  2045 * HOL/record: record_simproc (part of the default simpset) takes care
  2046 of selectors applied to updated records; record_split_tac is no longer
  2047 part of the default claset; update_defs may now be removed from the
  2048 simpset in many cases; COMPATIBILITY: old behavior achieved by
  2049 
  2050   claset_ref () := claset() addSWrapper record_split_wrapper;
  2051   Delsimprocs [record_simproc]
  2052 
  2053 * HOL/typedef: fixed type inference for representing set; type
  2054 arguments now have to occur explicitly on the rhs as type constraints;
  2055 
  2056 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  2057 names rather than an ML expression;
  2058 
  2059 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  2060 supplied later.  Program schemes can be defined, such as
  2061     "While B C s = (if B s then While B C (C s) else s)"
  2062 where the well-founded relation can be chosen after B and C have been given.
  2063 
  2064 * HOL/List: the constructors of type list are now Nil and Cons;
  2065 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  2066 course, ML tools referring to List.list.op # etc. have to be adapted;
  2067 
  2068 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  2069 disabled by default; run isabelle with option -m HOL to get back to
  2070 the original Gordon/HOL-style output;
  2071 
  2072 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  2073 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  2074 
  2075 * HOL basic syntax simplified (more orthogonal): all variants of
  2076 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  2077 Eps operator is provided as well: "SOME x. P[x]";
  2078 
  2079 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  2080 
  2081 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  2082 thus available for user theories;
  2083 
  2084 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  2085 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  2086 time;
  2087 
  2088 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  2089 several times and then mp;
  2090 
  2091 
  2092 *** LK ***
  2093 
  2094 * the notation <<...>> is now available as a notation for sequences of
  2095 formulas;
  2096 
  2097 * the simplifier is now installed
  2098 
  2099 * the axiom system has been generalized (thanks to Soren Heilmann)
  2100 
  2101 * the classical reasoner now has a default rule database
  2102 
  2103 
  2104 *** ZF ***
  2105 
  2106 * new primrec section allows primitive recursive functions to be given
  2107 directly (as in HOL) over datatypes and the natural numbers;
  2108 
  2109 * new tactics induct_tac and exhaust_tac for induction (or case
  2110 analysis) over datatypes and the natural numbers;
  2111 
  2112 * the datatype declaration of type T now defines the recursor T_rec;
  2113 
  2114 * simplification automatically does freeness reasoning for datatype
  2115 constructors;
  2116 
  2117 * automatic type-inference, with AddTCs command to insert new
  2118 type-checking rules;
  2119 
  2120 * datatype introduction rules are now added as Safe Introduction rules
  2121 to the claset;
  2122 
  2123 * the syntax "if P then x else y" is now available in addition to
  2124 if(P,x,y);
  2125 
  2126 
  2127 *** Internal programming interfaces ***
  2128 
  2129 * tuned simplifier trace output; new flag debug_simp;
  2130 
  2131 * structures Vartab / Termtab (instances of TableFun) offer efficient
  2132 tables indexed by indexname_ord / term_ord (compatible with aconv);
  2133 
  2134 * AxClass.axclass_tac lost the theory argument;
  2135 
  2136 * tuned current_goals_markers semantics: begin / end goal avoids
  2137 printing empty lines;
  2138 
  2139 * removed prs and prs_fn hook, which was broken because it did not
  2140 include \n in its semantics, forcing writeln to add one
  2141 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  2142 string -> unit if you really want to output text without newline;
  2143 
  2144 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  2145 plain output, interface builders may have to enable 'isabelle_font'
  2146 mode to get Isabelle font glyphs as before;
  2147 
  2148 * refined token_translation interface; INCOMPATIBILITY: output length
  2149 now of type real instead of int;
  2150 
  2151 * theory loader actions may be traced via new ThyInfo.add_hook
  2152 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  2153 your own database of information attached to *whole* theories -- as
  2154 opposed to intra-theory data slots offered via TheoryDataFun;
  2155 
  2156 * proper handling of dangling sort hypotheses (at last!);
  2157 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  2158 extra sort hypotheses that can be witnessed from the type signature;
  2159 the force_strip_shyps flag is gone, any remaining shyps are simply
  2160 left in the theorem (with a warning issued by strip_shyps_warning);
  2161 
  2162 
  2163 
  2164 New in Isabelle98-1 (October 1998)
  2165 ----------------------------------
  2166 
  2167 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2168 
  2169 * several changes of automated proof tools;
  2170 
  2171 * HOL: major changes to the inductive and datatype packages, including
  2172 some minor incompatibilities of theory syntax;
  2173 
  2174 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  2175 called `inj_on';
  2176 
  2177 * HOL: removed duplicate thms in Arith:
  2178   less_imp_add_less  should be replaced by  trans_less_add1
  2179   le_imp_add_le      should be replaced by  trans_le_add1
  2180 
  2181 * HOL: unary minus is now overloaded (new type constraints may be
  2182 required);
  2183 
  2184 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  2185 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  2186 now taken as an integer constant.
  2187 
  2188 * Pure: ML function 'theory_of' renamed to 'theory';
  2189 
  2190 
  2191 *** Proof tools ***
  2192 
  2193 * Simplifier:
  2194   1. Asm_full_simp_tac is now more aggressive.
  2195      1. It will sometimes reorient premises if that increases their power to
  2196         simplify.
  2197      2. It does no longer proceed strictly from left to right but may also
  2198         rotate premises to achieve further simplification.
  2199      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  2200      old Asm_full_simp_tac in that it does not rotate premises.
  2201   2. The simplifier now knows a little bit about nat-arithmetic.
  2202 
  2203 * Classical reasoner: wrapper mechanism for the classical reasoner now
  2204 allows for selected deletion of wrappers, by introduction of names for
  2205 wrapper functionals.  This implies that addbefore, addSbefore,
  2206 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  2207 and that adding two tactics with the same name overwrites the first
  2208 one (emitting a warning).
  2209   type wrapper = (int -> tactic) -> (int -> tactic)
  2210   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  2211   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  2212   delWrapper, delSWrapper: claset *  string            -> claset
  2213   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  2214 
  2215 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  2216 semantics; addbefore now affects only the unsafe part of step_tac
  2217 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  2218 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  2219 by Force_tac;
  2220 
  2221 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  2222 compWrapper; added safe wrapper (and access functions for it);
  2223 
  2224 * HOL/split_all_tac is now much faster and fails if there is nothing
  2225 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  2226 and the names of the automatically generated variables have changed.
  2227 split_all_tac has moved within claset() from unsafe wrappers to safe
  2228 wrappers, which means that !!-bound variables are split much more
  2229 aggressively, and safe_tac and clarify_tac now split such variables.
  2230 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  2231 Note: the same holds for record_split_tac, which does the job of
  2232 split_all_tac for record fields.
  2233 
  2234 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  2235 permanently to the default simpset using Addsplits just like
  2236 Addsimps. They can be removed via Delsplits just like
  2237 Delsimps. Lower-case versions are also available.
  2238 
  2239 * HOL/Simplifier: The rule split_if is now part of the default
  2240 simpset. This means that the simplifier will eliminate all occurrences
  2241 of if-then-else in the conclusion of a goal. To prevent this, you can
  2242 either remove split_if completely from the default simpset by
  2243 `Delsplits [split_if]' or remove it in a specific call of the
  2244 simplifier using `... delsplits [split_if]'.  You can also add/delete
  2245 other case splitting rules to/from the default simpset: every datatype
  2246 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  2247 t is the name of the datatype).
  2248 
  2249 * Classical reasoner / Simplifier combination: new force_tac (and
  2250 derivatives Force_tac, force) combines rewriting and classical
  2251 reasoning (and whatever other tools) similarly to auto_tac, but is
  2252 aimed to solve the given subgoal completely.
  2253 
  2254 
  2255 *** General ***
  2256 
  2257 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  2258 and `goalw': the theory is no longer needed as an explicit argument -
  2259 the current theory context is used; assumptions are no longer returned
  2260 at the ML-level unless one of them starts with ==> or !!; it is
  2261 recommended to convert to these new commands using isatool fixgoal
  2262 (backup your sources first!);
  2263 
  2264 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  2265 the current theory context, and 'theory' to lookup stored theories;
  2266 
  2267 * new theory section 'locale' for declaring constants, assumptions and
  2268 definitions that have local scope;
  2269 
  2270 * new theory section 'nonterminals' for purely syntactic types;
  2271 
  2272 * new theory section 'setup' for generic ML setup functions
  2273 (e.g. package initialization);
  2274 
  2275 * the distribution now includes Isabelle icons: see
  2276 lib/logo/isabelle-{small,tiny}.xpm;
  2277 
  2278 * isatool install - install binaries with absolute references to
  2279 ISABELLE_HOME/bin;
  2280 
  2281 * isatool logo -- create instances of the Isabelle logo (as EPS);
  2282 
  2283 * print mode 'emacs' reserved for Isamode;
  2284 
  2285 * support multiple print (ast) translations per constant name;
  2286 
  2287 * theorems involving oracles are now printed with a suffixed [!];
  2288 
  2289 
  2290 *** HOL ***
  2291 
  2292 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  2293 
  2294 * HOL/inductive package reorganized and improved: now supports mutual
  2295 definitions such as
  2296 
  2297   inductive EVEN ODD
  2298     intrs
  2299       null "0 : EVEN"
  2300       oddI "n : EVEN ==> Suc n : ODD"
  2301       evenI "n : ODD ==> Suc n : EVEN"
  2302 
  2303 new theorem list "elims" contains an elimination rule for each of the
  2304 recursive sets; inductive definitions now handle disjunctive premises
  2305 correctly (also ZF);
  2306 
  2307 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  2308 "mutual_induct" no longer exists - the induction rule is always
  2309 contained in "induct";
  2310 
  2311 
  2312 * HOL/datatype package re-implemented and greatly improved: now
  2313 supports mutually recursive datatypes such as
  2314 
  2315   datatype
  2316     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  2317             | SUM ('a aexp) ('a aexp)
  2318             | DIFF ('a aexp) ('a aexp)
  2319             | NUM 'a
  2320   and
  2321     'a bexp = LESS ('a aexp) ('a aexp)
  2322             | AND ('a bexp) ('a bexp)
  2323             | OR ('a bexp) ('a bexp)
  2324 
  2325 as well as indirectly recursive datatypes such as
  2326 
  2327   datatype
  2328     ('a, 'b) term = Var 'a
  2329                   | App 'b ((('a, 'b) term) list)
  2330 
  2331 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  2332 induction on mutually / indirectly recursive datatypes.
  2333 
  2334 Primrec equations are now stored in theory and can be accessed via
  2335 <function_name>.simps.
  2336 
  2337 INCOMPATIBILITIES:
  2338 
  2339   - Theories using datatypes must now have theory Datatype as an
  2340     ancestor.
  2341   - The specific <typename>.induct_tac no longer exists - use the
  2342     generic induct_tac instead.
  2343   - natE has been renamed to nat.exhaust - use exhaust_tac
  2344     instead of res_inst_tac ... natE. Note that the variable
  2345     names in nat.exhaust differ from the names in natE, this
  2346     may cause some "fragile" proofs to fail.
  2347   - The theorems split_<typename>_case and split_<typename>_case_asm
  2348     have been renamed to <typename>.split and <typename>.split_asm.
  2349   - Since default sorts of type variables are now handled correctly,
  2350     some datatype definitions may have to be annotated with explicit
  2351     sort constraints.
  2352   - Primrec definitions no longer require function name and type
  2353     of recursive argument.
  2354 
  2355 Consider using isatool fixdatatype to adapt your theories and proof
  2356 scripts to the new package (backup your sources first!).
  2357 
  2358 
  2359 * HOL/record package: considerably improved implementation; now
  2360 includes concrete syntax for record types, terms, updates; theorems
  2361 for surjective pairing and splitting !!-bound record variables; proof
  2362 support is as follows:
  2363 
  2364   1) standard conversions (selectors or updates applied to record
  2365 constructor terms) are part of the standard simpset;
  2366 
  2367   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  2368 made part of standard simpset and claset via addIffs;
  2369 
  2370   3) a tactic for record field splitting (record_split_tac) is part of
  2371 the standard claset (addSWrapper);
  2372 
  2373 To get a better idea about these rules you may retrieve them via
  2374 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  2375 the name of your record type.
  2376 
  2377 The split tactic 3) conceptually simplifies by the following rule:
  2378 
  2379   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  2380 
  2381 Thus any record variable that is bound by meta-all will automatically
  2382 blow up into some record constructor term, consequently the
  2383 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  2384 solve record problems automatically.
  2385 
  2386 
  2387 * reorganized the main HOL image: HOL/Integ and String loaded by
  2388 default; theory Main includes everything;
  2389 
  2390 * automatic simplification of integer sums and comparisons, using cancellation;
  2391 
  2392 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  2393 
  2394 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  2395 
  2396 * many new identities for unions, intersections, set difference, etc.;
  2397 
  2398 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  2399 called split_if, split_split, split_sum_case and split_nat_case (to go
  2400 with add/delsplits);
  2401 
  2402 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  2403 (?x::unit) = (); this is made part of the default simpset, which COULD
  2404 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  2405 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  2406 unit_abs_eta_conv is added in order to counter the effect of
  2407 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  2408 %u.f();
  2409 
  2410 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  2411 makes more sense);
  2412 
  2413 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2414   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2415   disjointness reasoning but breaking a few old proofs.
  2416 
  2417 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  2418 to 'converse' from 'inverse' (for compatibility with ZF and some
  2419 literature);
  2420 
  2421 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  2422 the well-founded relation;
  2423 
  2424 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  2425     Compl A.  The "Compl" syntax remains available as input syntax for this
  2426     release ONLY.
  2427 
  2428 * HOL/Update: new theory of function updates:
  2429     f(a:=b) == %x. if x=a then b else f x
  2430 may also be iterated as in f(a:=b,c:=d,...);
  2431 
  2432 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  2433 
  2434 * HOL/List:
  2435   - new function list_update written xs[i:=v] that updates the i-th
  2436     list position. May also be iterated as in xs[i:=a,j:=b,...].
  2437   - new function `upt' written [i..j(] which generates the list
  2438     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  2439     bound write [i..j], which is a shorthand for [i..j+1(].
  2440   - new lexicographic orderings and corresponding wellfoundedness theorems.
  2441 
  2442 * HOL/Arith:
  2443   - removed 'pred' (predecessor) function;
  2444   - generalized some theorems about n-1;
  2445   - many new laws about "div" and "mod";
  2446   - new laws about greatest common divisors (see theory ex/Primes);
  2447 
  2448 * HOL/Relation: renamed the relational operator r^-1 "converse"
  2449 instead of "inverse";
  2450 
  2451 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  2452   of the multiset ordering;
  2453 
  2454 * directory HOL/Real: a construction of the reals using Dedekind cuts
  2455   (not included by default);
  2456 
  2457 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  2458 
  2459 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  2460   programs, i.e. different program variables may have different types.
  2461 
  2462 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2463   [previously, this check worked only if the rewrite rule was unconditional]
  2464   Now rew can involve either definitions or equalities (either == or =).
  2465 
  2466 
  2467 *** ZF ***
  2468 
  2469 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  2470   only the theorems proved on ZF.ML;
  2471 
  2472 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2473   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2474   disjointness reasoning but breaking a few old proofs.
  2475 
  2476 * ZF/Update: new theory of function updates
  2477     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  2478   may also be iterated as in f(a:=b,c:=d,...);
  2479 
  2480 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  2481 
  2482 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2483   [previously, this check worked only if the rewrite rule was unconditional]
  2484   Now rew can involve either definitions or equalities (either == or =).
  2485 
  2486 * case_tac provided for compatibility with HOL
  2487     (like the old excluded_middle_tac, but with subgoals swapped)
  2488 
  2489 
  2490 *** Internal programming interfaces ***
  2491 
  2492 * Pure: several new basic modules made available for general use, see
  2493 also src/Pure/README;
  2494 
  2495 * improved the theory data mechanism to support encapsulation (data
  2496 kind name replaced by private Object.kind, acting as authorization
  2497 key); new type-safe user interface via functor TheoryDataFun; generic
  2498 print_data function becomes basically useless;
  2499 
  2500 * removed global_names compatibility flag -- all theory declarations
  2501 are qualified by default;
  2502 
  2503 * module Pure/Syntax now offers quote / antiquote translation
  2504 functions (useful for Hoare logic etc. with implicit dependencies);
  2505 see HOL/ex/Antiquote for an example use;
  2506 
  2507 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2508 cterm -> thm;
  2509 
  2510 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2511 subgoal;
  2512 
  2513 * Display.print_goals function moved to Locale.print_goals;
  2514 
  2515 * standard print function for goals supports current_goals_markers
  2516 variable for marking begin of proof, end of proof, start of goal; the
  2517 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2518 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2519 for example;
  2520 
  2521 
  2522 
  2523 New in Isabelle98 (January 1998)
  2524 --------------------------------
  2525 
  2526 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2527 
  2528 * changed lexical syntax of terms / types: dots made part of long
  2529 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2530 
  2531 * simpset (and claset) reference variable replaced by functions
  2532 simpset / simpset_ref;
  2533 
  2534 * no longer supports theory aliases (via merge) and non-trivial
  2535 implicit merge of thms' signatures;
  2536 
  2537 * most internal names of constants changed due to qualified names;
  2538 
  2539 * changed Pure/Sequence interface (see Pure/seq.ML);
  2540 
  2541 
  2542 *** General Changes ***
  2543 
  2544 * hierachically structured name spaces (for consts, types, axms, thms
  2545 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2546 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2547 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2548 long_names for fully qualified output names; NOTE: ML programs
  2549 (special tactics, packages etc.) referring to internal names may have
  2550 to be adapted to cope with fully qualified names; in case of severe
  2551 backward campatibility problems try setting 'global_names' at compile
  2552 time to have enrything declared within a flat name space; one may also
  2553 fine tune name declarations in theories via the 'global' and 'local'
  2554 section;
  2555 
  2556 * reimplemented the implicit simpset and claset using the new anytype
  2557 data filed in signatures; references simpset:simpset ref etc. are
  2558 replaced by functions simpset:unit->simpset and
  2559 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2560 to patch your ML files accordingly;
  2561 
  2562 * HTML output now includes theory graph data for display with Java
  2563 applet or isatool browser; data generated automatically via isatool
  2564 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2565 
  2566 * defs may now be conditional; improved rewrite_goals_tac to handle
  2567 conditional equations;
  2568 
  2569 * defs now admits additional type arguments, using TYPE('a) syntax;
  2570 
  2571 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2572 creates a new theory node; implicit merge of thms' signatures is
  2573 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2574 transfer:theory->thm->thm in (rare) cases;
  2575 
  2576 * improved handling of draft signatures / theories; draft thms (and
  2577 ctyps, cterms) are automatically promoted to real ones;
  2578 
  2579 * slightly changed interfaces for oracles: admit many per theory, named
  2580 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2581 
  2582 * print_goals: optional output of const types (set show_consts and
  2583 show_types);
  2584 
  2585 * improved output of warnings (###) and errors (***);
  2586 
  2587 * subgoal_tac displays a warning if the new subgoal has type variables;
  2588 
  2589 * removed old README and Makefiles;
  2590 
  2591 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2592 
  2593 * removed obsolete init_pps and init_database;
  2594 
  2595 * deleted the obsolete tactical STATE, which was declared by
  2596     fun STATE tacfun st = tacfun st st;
  2597 
  2598 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2599 (which abbreviates $HOME);
  2600 
  2601 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2602 use isatool fixseq to adapt your ML programs (this works for fully
  2603 qualified references to the Sequence structure only!);
  2604 
  2605 * use_thy no longer requires writable current directory; it always
  2606 reloads .ML *and* .thy file, if either one is out of date;
  2607 
  2608 
  2609 *** Classical Reasoner ***
  2610 
  2611 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2612 tactics that use classical reasoning to simplify a subgoal without
  2613 splitting it into several subgoals;
  2614 
  2615 * Safe_tac: like safe_tac but uses the default claset;
  2616 
  2617 
  2618 *** Simplifier ***
  2619 
  2620 * added simplification meta rules:
  2621     (asm_)(full_)simplify: simpset -> thm -> thm;
  2622 
  2623 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2624 logics (again);
  2625 
  2626 * added prems argument to simplification procedures;
  2627 
  2628 * HOL, FOL, ZF: added infix function `addsplits':
  2629   instead of `<simpset> setloop (split_tac <thms>)'
  2630   you can simply write `<simpset> addsplits <thms>'
  2631 
  2632 
  2633 *** Syntax ***
  2634 
  2635 * TYPE('a) syntax for type reflection terms;
  2636 
  2637 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2638 
  2639 * pretty printer: changed order of mixfix annotation preference (again!);
  2640 
  2641 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2642 
  2643 
  2644 *** HOL ***
  2645 
  2646 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2647   with `addloop' of the simplifier to faciliate case splitting in premises.
  2648 
  2649 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2650 
  2651 * HOL/Auth: new protocol proofs including some for the Internet
  2652   protocol TLS;
  2653 
  2654 * HOL/Map: new theory of `maps' a la VDM;
  2655 
  2656 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2657 cancelling out common nat summands from =, <, <= (in)equalities, or
  2658 differences; simplification procedures nat_cancel_factor for
  2659 cancelling common factor from =, <, <= (in)equalities over natural
  2660 sums; nat_cancel contains both kinds of procedures, it is installed by
  2661 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2662 
  2663 * HOL/simplifier: terms of the form
  2664   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2665   are rewritten to
  2666   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2667   and those of the form
  2668   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2669   are rewritten to
  2670   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2671 
  2672 * HOL/datatype
  2673   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2674 
  2675   P(t_case f1 ... fn x) =
  2676      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2677         ...
  2678        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2679      )
  2680 
  2681   and a theorem `split_t_case_asm' of the form
  2682 
  2683   P(t_case f1 ... fn x) =
  2684     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2685         ...
  2686        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2687      )
  2688   which can be added to a simpset via `addsplits'. The existing theorems
  2689   expand_list_case and expand_option_case have been renamed to
  2690   split_list_case and split_option_case.
  2691 
  2692 * HOL/Arithmetic:
  2693   - `pred n' is automatically converted to `n-1'.
  2694     Users are strongly encouraged not to use `pred' any longer,
  2695     because it will disappear altogether at some point.
  2696   - Users are strongly encouraged to write "0 < n" rather than
  2697     "n ~= 0". Theorems and proof tools have been modified towards this
  2698     `standard'.
  2699 
  2700 * HOL/Lists:
  2701   the function "set_of_list" has been renamed "set" (and its theorems too);
  2702   the function "nth" now takes its arguments in the reverse order and
  2703   has acquired the infix notation "!" as in "xs!n".
  2704 
  2705 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2706 
  2707 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2708   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2709 
  2710 * HOL/record: extensible records with schematic structural subtyping
  2711 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2712 still lacks various theorems and concrete record syntax;
  2713 
  2714 
  2715 *** HOLCF ***
  2716 
  2717 * removed "axioms" and "generated by" sections;
  2718 
  2719 * replaced "ops" section by extended "consts" section, which is capable of
  2720   handling the continuous function space "->" directly;
  2721 
  2722 * domain package:
  2723   . proves theorems immediately and stores them in the theory,
  2724   . creates hierachical name space,
  2725   . now uses normal mixfix annotations (instead of cinfix...),
  2726   . minor changes to some names and values (for consistency),
  2727   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2728   . separator between mutual domain defs: changed "," to "and",
  2729   . improved handling of sort constraints;  now they have to
  2730     appear on the left-hand side of the equations only;
  2731 
  2732 * fixed LAM <x,y,zs>.b syntax;
  2733 
  2734 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2735 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2736 
  2737 
  2738 *** FOL and ZF ***
  2739 
  2740 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2741   with `addloop' of the simplifier to faciliate case splitting in premises.
  2742 
  2743 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2744 in HOL, they strip ALL and --> from proved theorems;
  2745 
  2746 
  2747 
  2748 New in Isabelle94-8 (May 1997)
  2749 ------------------------------
  2750 
  2751 *** General Changes ***
  2752 
  2753 * new utilities to build / run / maintain Isabelle etc. (in parts
  2754 still somewhat experimental); old Makefiles etc. still functional;
  2755 
  2756 * new 'Isabelle System Manual';
  2757 
  2758 * INSTALL text, together with ./configure and ./build scripts;
  2759 
  2760 * reimplemented type inference for greater efficiency, better error
  2761 messages and clean internal interface;
  2762 
  2763 * prlim command for dealing with lots of subgoals (an easier way of
  2764 setting goals_limit);
  2765 
  2766 
  2767 *** Syntax ***
  2768 
  2769 * supports alternative (named) syntax tables (parser and pretty
  2770 printer); internal interface is provided by add_modesyntax(_i);
  2771 
  2772 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2773 be used in conjunction with the Isabelle symbol font; uses the
  2774 "symbols" syntax table;
  2775 
  2776 * added token_translation interface (may translate name tokens in
  2777 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2778 the current print_mode); IMPORTANT: user print translation functions
  2779 are responsible for marking newly introduced bounds
  2780 (Syntax.mark_boundT);
  2781 
  2782 * token translations for modes "xterm" and "xterm_color" that display
  2783 names in bold, underline etc. or colors (which requires a color
  2784 version of xterm);
  2785 
  2786 * infixes may now be declared with names independent of their syntax;
  2787 
  2788 * added typed_print_translation (like print_translation, but may
  2789 access type of constant);
  2790 
  2791 
  2792 *** Classical Reasoner ***
  2793 
  2794 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2795 some limitations.  Blast_tac...
  2796   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2797   + ignores elimination rules that don't have the correct format
  2798         (the conclusion MUST be a formula variable)
  2799   + ignores types, which can make HOL proofs fail
  2800   + rules must not require higher-order unification, e.g. apply_type in ZF
  2801     [message "Function Var's argument not a bound variable" relates to this]
  2802   + its proof strategy is more general but can actually be slower
  2803 
  2804 * substitution with equality assumptions no longer permutes other
  2805 assumptions;
  2806 
  2807 * minor changes in semantics of addafter (now called addaltern); renamed
  2808 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2809 (and access functions for it);
  2810 
  2811 * improved combination of classical reasoner and simplifier:
  2812   + functions for handling clasimpsets
  2813   + improvement of addss: now the simplifier is called _after_ the
  2814     safe steps.
  2815   + safe variant of addss called addSss: uses safe simplifications
  2816     _during_ the safe steps. It is more complete as it allows multiple
  2817     instantiations of unknowns (e.g. with slow_tac).
  2818 
  2819 *** Simplifier ***
  2820 
  2821 * added interface for simplification procedures (functions that
  2822 produce *proven* rewrite rules on the fly, depending on current
  2823 redex);
  2824 
  2825 * ordering on terms as parameter (used for ordered rewriting);
  2826 
  2827 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2828 
  2829 * the solver is now split into a safe and an unsafe part.
  2830 This should be invisible for the normal user, except that the
  2831 functions setsolver and addsolver have been renamed to setSolver and
  2832 addSolver; added safe_asm_full_simp_tac;
  2833 
  2834 
  2835 *** HOL ***
  2836 
  2837 * a generic induction tactic `induct_tac' which works for all datatypes and
  2838 also for type `nat';
  2839 
  2840 * a generic case distinction tactic `exhaust_tac' which works for all
  2841 datatypes and also for type `nat';
  2842 
  2843 * each datatype comes with a function `size';
  2844 
  2845 * patterns in case expressions allow tuple patterns as arguments to
  2846 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2847 
  2848 * primrec now also works with type nat;
  2849 
  2850 * recdef: a new declaration form, allows general recursive functions to be
  2851 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2852 
  2853 * the constant for negation has been renamed from "not" to "Not" to
  2854 harmonize with FOL, ZF, LK, etc.;
  2855 
  2856 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2857 infinite lists;
  2858 
  2859 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2860 
  2861 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2862 problems in commutative rings, using axiomatic type classes for + and *;
  2863 
  2864 * more examples in HOL/MiniML and HOL/Auth;
  2865 
  2866 * more default rewrite rules for quantifiers, union/intersection;
  2867 
  2868 * a new constant `arbitrary == @x.False';
  2869 
  2870 * HOLCF/IOA replaces old HOL/IOA;
  2871 
  2872 * HOLCF changes: derived all rules and arities
  2873   + axiomatic type classes instead of classes
  2874   + typedef instead of faking type definitions
  2875   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2876   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2877   + eliminated the types void, one, tr
  2878   + use unit lift and bool lift (with translations) instead of one and tr
  2879   + eliminated blift from Lift3.thy (use Def instead of blift)
  2880   all eliminated rules are derived as theorems --> no visible changes ;
  2881 
  2882 
  2883 *** ZF ***
  2884 
  2885 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2886 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2887 as ZF_cs addSIs [equalityI];
  2888 
  2889 
  2890 
  2891 New in Isabelle94-7 (November 96)
  2892 ---------------------------------
  2893 
  2894 * allowing negative levels (as offsets) in prlev and choplev;
  2895 
  2896 * super-linear speedup for large simplifications;
  2897 
  2898 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2899 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2900 FAIL); can suppress it using the command Delsimps (ex_simps @
  2901 all_simps); De Morgan laws are also now included, by default;
  2902 
  2903 * improved printing of ==>  :  ~:
  2904 
  2905 * new object-logic "Sequents" adds linear logic, while replacing LK
  2906 and Modal (thanks to Sara Kalvala);
  2907 
  2908 * HOL/Auth: correctness proofs for authentication protocols;
  2909 
  2910 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2911 examples on HOL/Auth);
  2912 
  2913 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2914 the rewriter and classical reasoner simultaneously;
  2915 
  2916 * function uresult no longer returns theorems in "standard" format;
  2917 regain previous version by: val uresult = standard o uresult;
  2918 
  2919 
  2920 
  2921 New in Isabelle94-6
  2922 -------------------
  2923 
  2924 * oracles -- these establish an interface between Isabelle and trusted
  2925 external reasoners, which may deliver results as theorems;
  2926 
  2927 * proof objects (in particular record all uses of oracles);
  2928 
  2929 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2930 
  2931 * "constdefs" section in theory files;
  2932 
  2933 * "primrec" section (HOL) no longer requires names;
  2934 
  2935 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2936 
  2937 
  2938 
  2939 New in Isabelle94-5
  2940 -------------------
  2941 
  2942 * reduced space requirements;
  2943 
  2944 * automatic HTML generation from theories;
  2945 
  2946 * theory files no longer require "..." (quotes) around most types;
  2947 
  2948 * new examples, including two proofs of the Church-Rosser theorem;
  2949 
  2950 * non-curried (1994) version of HOL is no longer distributed;
  2951 
  2952 
  2953 
  2954 New in Isabelle94-4
  2955 -------------------
  2956 
  2957 * greatly reduced space requirements;
  2958 
  2959 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2960 
  2961 * searchable theorem database (see the section "Retrieving theorems" on
  2962 page 8 of the Reference Manual);
  2963 
  2964 * new examples, including Grabczewski's monumental case study of the
  2965 Axiom of Choice;
  2966 
  2967 * The previous version of HOL renamed to Old_HOL;
  2968 
  2969 * The new version of HOL (previously called CHOL) uses a curried syntax
  2970 for functions.  Application looks like f a b instead of f(a,b);
  2971 
  2972 * Mutually recursive inductive definitions finally work in HOL;
  2973 
  2974 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2975 translates to the operator "split";
  2976 
  2977 
  2978 
  2979 New in Isabelle94-3
  2980 -------------------
  2981 
  2982 * new infix operator, addss, allowing the classical reasoner to
  2983 perform simplification at each step of its search.  Example:
  2984         fast_tac (cs addss ss)
  2985 
  2986 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2987 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2988 look like (a,b) instead of <a,b>;
  2989 
  2990 * PLEASE NOTE: CHOL will eventually replace HOL!
  2991 
  2992 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2993 It translates to the operator "split".  A new theory of integers is available;
  2994 
  2995 * In ZF, integer numerals now denote two's-complement binary integers.
  2996 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2997 
  2998 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2999 of the Axiom of Choice;
  3000 
  3001 
  3002 
  3003 New in Isabelle94-2
  3004 -------------------
  3005 
  3006 * Significantly faster resolution;
  3007 
  3008 * the different sections in a .thy file can now be mixed and repeated
  3009 freely;
  3010 
  3011 * Database of theorems for FOL, HOL and ZF.  New
  3012 commands including qed, qed_goal and bind_thm store theorems in the database.
  3013 
  3014 * Simple database queries: return a named theorem (get_thm) or all theorems of
  3015 a given theory (thms_of), or find out what theory a theorem was proved in
  3016 (theory_of_thm);
  3017 
  3018 * Bugs fixed in the inductive definition and datatype packages;
  3019 
  3020 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  3021 and HOL_dup_cs obsolete;
  3022 
  3023 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  3024 have been removed;
  3025 
  3026 * Simpler definition of function space in ZF;
  3027 
  3028 * new results about cardinal and ordinal arithmetic in ZF;
  3029 
  3030 * 'subtype' facility in HOL for introducing new types as subsets of existing
  3031 types;
  3032 
  3033 
  3034 $Id$