NEWS
author paulson
Mon Jan 24 12:41:06 2005 +0100 (2005-01-24)
changeset 15454 4b339d3907a0
parent 15436 d059da8434a5
child 15475 fdf9434b04ea
permissions -rw-r--r--
thin_tac now works on P==>Q
     1 Isabelle NEWS -- history user-relevant changes
     2 ==============================================
     3 
     4 New in this Isabelle release
     5 ----------------------------
     6 
     7 *** General ***
     8 
     9 * Document preparation: new antiquotations @{lhs thm} and @{rhs thm}
    10   printing the lhs/rhs of definitions, equations, inequations etc. 
    11 
    12 * isatool usedir: new option -f that allows specification of the ML
    13   file to be used by Isabelle; default is ROOT.ML.
    14 
    15 * Theory headers: the new header syntax for Isar theories is
    16 
    17   theory <name>
    18   imports <theory1> ... <theoryn>
    19   begin
    20 
    21   optionally also with a "files" section. The syntax
    22 
    23   theory <name> = <theory1> + ... + <theoryn>:
    24 
    25   will still be supported for some time but will eventually disappear.
    26   The syntax of old-style theories has not changed.
    27 
    28 * Provers/quasi.ML:  new transitivity reasoners for transitivity only
    29   and quasi orders.
    30 
    31 * Provers/trancl.ML:  new transitivity reasoner for transitive and
    32   reflexive-transitive closure of relations.
    33 
    34 * Provers/blast.ML:  new reference depth_limit to make blast's depth
    35   limit (previously hard-coded with a value of 20) user-definable.
    36 
    37 * Pure: thin_tac now works even if the assumption being deleted contains !! or ==>. 
    38   More generally, erule now works even if the major premise of the elimination rule
    39   contains !! or ==>.
    40 
    41 * Pure: considerably improved version of 'constdefs' command.  Now
    42   performs automatic type-inference of declared constants; additional
    43   support for local structure declarations (cf. locales and HOL
    44   records), see also isar-ref manual.  Potential INCOMPATIBILITY: need
    45   to observe strictly sequential dependencies of definitions within a
    46   single 'constdefs' section; moreover, the declared name needs to be
    47   an identifier.  If all fails, consider to fall back on 'consts' and
    48   'defs' separately.
    49 
    50 * Pure: improved indexed syntax and implicit structures.  First of
    51   all, indexed syntax provides a notational device for subscripted
    52   application, using the new syntax \<^bsub>term\<^esub> for arbitrary
    53   expressions.  Secondly, in a local context with structure
    54   declarations, number indexes \<^sub>n or the empty index (default
    55   number 1) refer to a certain fixed variable implicitly; option
    56   show_structs controls printing of implicit structures.  Typical
    57   applications of these concepts involve record types and locales.
    58 
    59 * Pure: clear separation of logical types and nonterminals, where the
    60   latter may only occur in 'syntax' specifications or type
    61   abbreviations.  Before that distinction was only partially
    62   implemented via type class "logic" vs. "{}".  Potential
    63   INCOMPATIBILITY in rare cases of improper use of 'types'/'consts'
    64   instead of 'nonterminals'/'syntax'.  Some very exotic syntax
    65   specifications may require further adaption (e.g. Cube/Base.thy).
    66 
    67 * Pure: removed obsolete type class "logic", use the top sort {}
    68   instead.  Note that non-logical types should be declared as
    69   'nonterminals' rather than 'types'.  INCOMPATIBILITY for new
    70   object-logic specifications.
    71 
    72 * Pure: print_tac now outputs the goal through the trace channel.
    73 
    74 * Pure: reference Namespace.unique_names included.  If true the
    75   (shortest) namespace-prefix is printed to disambiguate conflicts (as
    76   yet). If false the first entry wins (as during parsing). Default
    77   value is true.
    78 
    79 * Pure: tuned internal renaming of symbolic identifiers -- attach
    80   primes instead of base 26 numbers.
    81 
    82 * Pure/Syntax: inner syntax includes (*(*nested*) comments*).
    83 
    84 * Pure/Syntax: pretty pinter now supports unbreakable blocks,
    85   specified in mixfix annotations as "(00...)".
    86 
    87 * Pure/Syntax: 'advanced' translation functions (parse_translation
    88   etc.) may depend on the signature of the theory context being
    89   presently used for parsing/printing, see also isar-ref manual.
    90 
    91 * Pure/Simplifier: simplification procedures may now take the current
    92   simpset into account (cf. Simplifier.simproc(_i) / mk_simproc
    93   interface), which is very useful for calling the Simplifier
    94   recursively.  Minor INCOMPATIBILITY: the 'prems' argument of
    95   simprocs is gone -- use prems_of_ss on the simpset instead.
    96   Moreover, the low-level mk_simproc no longer applies Logic.varify
    97   internally, to allow for use in a context of fixed variables.
    98 
    99 * Pure/Simplifier: Command "find_rewrites" takes a string and lists all
   100   equality theorems (not just those with attribute simp!) whose left-hand
   101   side matches the term given via the string. In PG the command can be
   102   activated via Isabelle -> Show me -> matching rewrites.
   103 
   104 * Provers: Simplifier and Classical Reasoner now support proof context
   105   dependent plug-ins (simprocs, solvers, wrappers etc.).  These extra
   106   components are stored in the theory and patched into the
   107   simpset/claset when used in an Isar proof context.  Context
   108   dependent components are maintained by the following theory
   109   operations:
   110 
   111     Simplifier.add_context_simprocs
   112     Simplifier.del_context_simprocs
   113     Simplifier.set_context_subgoaler
   114     Simplifier.reset_context_subgoaler
   115     Simplifier.add_context_looper
   116     Simplifier.del_context_looper
   117     Simplifier.add_context_unsafe_solver
   118     Simplifier.add_context_safe_solver
   119 
   120     Classical.add_context_safe_wrapper
   121     Classical.del_context_safe_wrapper
   122     Classical.add_context_unsafe_wrapper
   123     Classical.del_context_unsafe_wrapper
   124 
   125   IMPORTANT NOTE: proof tools (methods etc.) need to use
   126   local_simpset_of and local_claset_of to instead of the primitive
   127   Simplifier.get_local_simpset and Classical.get_local_claset,
   128   respectively, in order to see the context dependent fields!
   129 
   130 * Document preparation: antiquotations now provide the option
   131   'locale=NAME' to specify an alternative context used for evaluating
   132   and printing the subsequent argument, as in @{thm [locale=LC]
   133   fold_commute}, for example.
   134 
   135 * Document preparation: commands 'display_drafts' and 'print_drafts'
   136   perform simple output of raw sources.  Only those symbols that do
   137   not require additional LaTeX packages (depending on comments in
   138   isabellesym.sty) are displayed properly, everything else is left
   139   verbatim.  We use isatool display and isatool print as front ends;
   140   these are subject to the DVI_VIEWER and PRINT_COMMAND settings,
   141   respectively.
   142 
   143 * Document preparation: Proof scripts as well as some other commands
   144   such as ML or parse/print_translation can now be hidden in the document.
   145   Hiding can be enabled either via the option '-H true' of isatool usedir
   146   or by setting the reference variable IsarOutput.hide_commands. Additional
   147   commands to be hidden may be declared using IsarOutput.add_hidden_commands.
   148 
   149 * ML: output via the Isabelle channels of writeln/warning/error
   150   etc. is now passed through Output.output, with a hook for arbitrary
   151   transformations depending on the print_mode (cf. Output.add_mode --
   152   the first active mode that provides a output function wins).
   153   Already formatted output may be embedded into further text via
   154   Output.raw; the result of Pretty.string_of/str_of and derived
   155   functions (string_of_term/cterm/thm etc.) is already marked raw to
   156   accommodate easy composition of diagnostic messages etc.
   157   Programmers rarely need to care about Output.output or Output.raw at
   158   all, with some notable exceptions: Output.output is required when
   159   bypassing the standard channels (writeln etc.), or in token
   160   translations to produce properly formatted results; Output.raw is
   161   required when capturing already output material that will eventually
   162   be presented to the user a second time.  For the default print mode,
   163   both Output.output and Output.raw have no effect.
   164 
   165 
   166 *** Isar ***
   167 
   168 * Locales:
   169   - "includes" disallowed in declaration of named locales (command "locale").
   170   - Fixed parameter management in theorem generation for goals with "includes".
   171     INCOMPATIBILITY: rarely, the generated theorem statement is different.
   172  
   173 *** HOL ***
   174 
   175 * Datatype induction via method `induct' now preserves the name of the
   176   induction variable. For example, when proving P(xs::'a list) by induction
   177   on xs, the induction step is now P(xs) ==> P(a#xs) rather than
   178   P(list) ==> P(a#list) as previously.
   179 
   180 * HOL/record: reimplementation of records. Improved scalability for
   181   records with many fields, avoiding performance problems for type
   182   inference. Records are no longer composed of nested field types, but
   183   of nested extension types. Therefore the record type only grows
   184   linear in the number of extensions and not in the number of fields.
   185   The top-level (users) view on records is preserved.  Potential
   186   INCOMPATIBILITY only in strange cases, where the theory depends on
   187   the old record representation. The type generated for a record is
   188   called <record_name>_ext_type.
   189 
   190 * HOL/record: Reference record_quick_and_dirty_sensitive can be
   191   enabled to skip the proofs triggered by a record definition or a
   192   simproc (if quick_and_dirty is enabled). Definitions of large
   193   records can take quite long.
   194 
   195 * HOL/record: "record_upd_simproc" for simplification of multiple
   196   record updates enabled by default.  Moreover, trivial updates are
   197   also removed: r(|x := x r|) = r.  INCOMPATIBILITY: old proofs break
   198   occasionally, since simplification is more powerful by default.
   199 
   200 * HOL: symbolic syntax of Hilbert Choice Operator is now as follows:
   201 
   202   syntax (epsilon)
   203     "_Eps" :: "[pttrn, bool] => 'a"    ("(3\<some>_./ _)" [0, 10] 10)
   204 
   205   The symbol \<some> is displayed as the alternative epsilon of LaTeX
   206   and x-symbol; use option '-m epsilon' to get it actually printed.
   207   Moreover, the mathematically important symbolic identifier
   208   \<epsilon> becomes available as variable, constant etc.
   209 
   210 * HOL: "x > y" abbreviates "y < x" and "x >= y" abbreviates "y <= x".
   211   Similarly for all quantifiers: "ALL x > y" etc.
   212   The x-symbol for >= is \<ge>.
   213 
   214 * HOL/SetInterval: The syntax for open intervals has changed:
   215 
   216   Old         New
   217   {..n(}   -> {..<n}
   218   {)n..}   -> {n<..}
   219   {m..n(}  -> {m..<n}
   220   {)m..n}  -> {m<..n}
   221   {)m..n(} -> {m<..<n}
   222 
   223   The old syntax is still supported but will disappear in the future.
   224   For conversion use the following emacs search and replace patterns:
   225 
   226   {)\([^\.]*\)\.\.  ->  {\1<\.\.}
   227   \.\.\([^(}]*\)(}  ->  \.\.<\1}
   228 
   229   They are not perfect but work quite well.
   230 
   231 * HOL: The syntax for 'setsum', summation over finite sets, has changed:
   232 
   233   The syntax for 'setsum (%x. e) A' used to be '\<Sum>x:A. e'
   234   and is now either 'SUM x:A. e' or '\<Sum>x\<in>A. e'.
   235 
   236   There is new syntax for summation over finite sets:
   237 
   238   '\<Sum>x | P. e'    is the same as  'setsum (%x. e) {x. P}'
   239   '\<Sum>x=a..b. e'   is the same as  'setsum (%x. e) {a..b}'
   240   '\<Sum>x=a..<b. e'  is the same as  'setsum (%x. e) {a..<b}'
   241   '\<Sum>x<k. e'      is the same as  'setsum (%x. e) {..<k}'
   242 
   243   Function 'Summation' over nat is gone, its syntax '\<Sum>i<k. e'
   244   now translates into 'setsum' as above.
   245 
   246 * HOL: Finite set induction: In Isar proofs, the insert case is now
   247   "case (insert x F)" instead of the old counterintuitive "case (insert F x)".
   248 
   249 * HOL/Simplifier:
   250 
   251   - Is now set up to reason about transitivity chains involving "trancl"
   252   (r^+) and "rtrancl" (r^*) by setting up tactics provided by
   253   Provers/trancl.ML as additional solvers.  INCOMPATIBILITY: old proofs break
   254   occasionally as simplification may now solve more goals than previously.
   255 
   256   - Converts x <= y into x = y if assumption y <= x is present.  Works for
   257   all partial orders (class "order"), in particular numbers and sets. For
   258   linear orders (e.g. numbers) it treats ~ x < y just like y <= x.
   259 
   260   - Simproc for "let x = a in f x"
   261   If a is a free or bound variable or a constant then the let is unfolded.
   262   Otherwise first a is simplified to a', and then f a' is simplified to
   263   g. If possible we abstract a' from g arriving at "let x = a' in g' x",
   264   otherwise we unfold the let and arrive at g. The simproc can be 
   265   enabled/disabled by the reference use_let_simproc. Potential
   266   INCOMPATIBILITY since simplification is more powerful by default.
   267  
   268 * HOL: new 'isatool dimacs2hol' to convert files in DIMACS CNF format
   269   (containing Boolean satisfiability problems) into Isabelle/HOL theories.
   270 
   271 
   272 *** HOLCF ***
   273 
   274 * HOLCF: discontinued special version of 'constdefs' (which used to
   275   support continuous functions) in favor of the general Pure one with
   276   full type-inference.
   277 
   278 
   279 *** ZF ***
   280 
   281 * ZF/ex/{Group,Ring}: examples in abstract algebra, including the
   282   First Isomorphism Theorem (on quotienting by the kernel of a
   283   homomorphism).
   284 
   285 * ZF/Simplifier: install second copy of type solver that actually
   286   makes use of TC rules declared to Isar proof contexts (or locales);
   287   the old version is still required for ML proof scripts.
   288 
   289 
   290 
   291 New in Isabelle2004 (April 2004)
   292 --------------------------------
   293 
   294 *** General ***
   295 
   296 * Provers/order.ML:  new efficient reasoner for partial and linear orders.
   297   Replaces linorder.ML.
   298 
   299 * Pure: Greek letters (except small lambda, \<lambda>), as well as Gothic
   300   (\<aa>...\<zz>\<AA>...\<ZZ>), calligraphic (\<A>...\<Z>), and Euler
   301   (\<a>...\<z>), are now considered normal letters, and can therefore
   302   be used anywhere where an ASCII letter (a...zA...Z) has until
   303   now. COMPATIBILITY: This obviously changes the parsing of some
   304   terms, especially where a symbol has been used as a binder, say
   305   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed
   306   as an identifier.  Fix it by inserting a space around former
   307   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in
   308   existing theory and ML files.
   309 
   310 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.
   311 
   312 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now
   313   allowed in identifiers. Similar to Greek letters \<^isub> is now considered
   314   a normal (but invisible) letter. For multiple letter subscripts repeat
   315   \<^isub> like this: x\<^isub>1\<^isub>2.
   316 
   317 * Pure: There are now sub-/superscripts that can span more than one
   318   character. Text between \<^bsub> and \<^esub> is set in subscript in
   319   ProofGeneral and LaTeX, text between \<^bsup> and \<^esup> in
   320   superscript. The new control characters are not identifier parts.
   321 
   322 * Pure: Control-symbols of the form \<^raw:...> will literally print the
   323   content of "..." to the latex file instead of \isacntrl... . The "..."
   324   may consist of any printable characters excluding the end bracket >.
   325 
   326 * Pure: Using new Isar command "finalconsts" (or the ML functions
   327   Theory.add_finals or Theory.add_finals_i) it is now possible to
   328   declare constants "final", which prevents their being given a definition
   329   later.  It is useful for constants whose behaviour is fixed axiomatically
   330   rather than definitionally, such as the meta-logic connectives.
   331 
   332 * Pure: 'instance' now handles general arities with general sorts
   333   (i.e. intersections of classes),
   334 
   335 * Presentation: generated HTML now uses a CSS style sheet to make layout
   336   (somewhat) independent of content. It is copied from lib/html/isabelle.css.
   337   It can be changed to alter the colors/layout of generated pages.
   338 
   339 
   340 *** Isar ***
   341 
   342 * Tactic emulation methods rule_tac, erule_tac, drule_tac, frule_tac,
   343   cut_tac, subgoal_tac and thin_tac:
   344   - Now understand static (Isar) contexts.  As a consequence, users of Isar
   345     locales are no longer forced to write Isar proof scripts.
   346     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic
   347     emulations.
   348   - INCOMPATIBILITY: names of variables to be instantiated may no
   349     longer be enclosed in quotes.  Instead, precede variable name with `?'.
   350     This is consistent with the instantiation attribute "where".
   351 
   352 * Attributes "where" and "of":
   353   - Now take type variables of instantiated theorem into account when reading
   354     the instantiation string.  This fixes a bug that caused instantiated
   355     theorems to have too special types in some circumstances.
   356   - "where" permits explicit instantiations of type variables.
   357 
   358 * Calculation commands "moreover" and "also" no longer interfere with
   359   current facts ("this"), admitting arbitrary combinations with "then"
   360   and derived forms.
   361 
   362 * Locales:
   363   - Goal statements involving the context element "includes" no longer
   364     generate theorems with internal delta predicates (those ending on
   365     "_axioms") in the premise.
   366     Resolve particular premise with <locale>.intro to obtain old form.
   367   - Fixed bug in type inference ("unify_frozen") that prevented mix of target
   368     specification and "includes" elements in goal statement.
   369   - Rule sets <locale>.intro and <locale>.axioms no longer declared as
   370     [intro?] and [elim?] (respectively) by default.
   371   - Experimental command for instantiation of locales in proof contexts:
   372         instantiate <label>[<attrs>]: <loc>
   373     Instantiates locale <loc> and adds all its theorems to the current context
   374     taking into account their attributes.  Label and attrs are optional
   375     modifiers, like in theorem declarations.  If present, names of
   376     instantiated theorems are qualified with <label>, and the attributes
   377     <attrs> are applied after any attributes these theorems might have already.
   378       If the locale has assumptions, a chained fact of the form
   379     "<loc> t1 ... tn" is expected from which instantiations of the parameters
   380     are derived.  The command does not support old-style locales declared
   381     with "locale (open)".
   382       A few (very simple) examples can be found in FOL/ex/LocaleInst.thy.
   383 
   384 * HOL: Tactic emulation methods induct_tac and case_tac understand static
   385   (Isar) contexts.
   386 
   387 
   388 *** HOL ***
   389 
   390 * Proof import: new image HOL4 contains the imported library from
   391   the HOL4 system with about 2500 theorems. It is imported by
   392   replaying proof terms produced by HOL4 in Isabelle. The HOL4 image
   393   can be used like any other Isabelle image.  See
   394   HOL/Import/HOL/README for more information.
   395 
   396 * Simplifier:
   397   - Much improved handling of linear and partial orders.
   398     Reasoners for linear and partial orders are set up for type classes
   399     "linorder" and "order" respectively, and are added to the default simpset
   400     as solvers.  This means that the simplifier can build transitivity chains
   401     to solve goals from the assumptions.
   402   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications
   403     of blast or auto after simplification become unnecessary because the goal
   404     is solved by simplification already.
   405 
   406 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws,
   407     all proved in axiomatic type classes for semirings, rings and fields.
   408 
   409 * Numerics:
   410   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are
   411     now formalized using the Ring_and_Field theory mentioned above.
   412   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently
   413     than before, because now they are set up once in a generic manner.
   414   - INCOMPATIBILITY: many type-specific arithmetic laws have gone.
   415     Look for the general versions in Ring_and_Field (and Power if they concern
   416     exponentiation).
   417 
   418 * Type "rat" of the rational numbers is now available in HOL-Complex.
   419 
   420 * Records:
   421   - Record types are now by default printed with their type abbreviation
   422     instead of the list of all field types. This can be configured via
   423     the reference "print_record_type_abbr".
   424   - Simproc "record_upd_simproc" for simplification of multiple updates added
   425     (not enabled by default).
   426   - Simproc "record_ex_sel_eq_simproc" to simplify EX x. sel r = x resp.
   427     EX x. x = sel r to True (not enabled by default).
   428   - Tactic "record_split_simp_tac" to split and simplify records added.
   429 
   430 * 'specification' command added, allowing for definition by
   431   specification.  There is also an 'ax_specification' command that
   432   introduces the new constants axiomatically.
   433 
   434 * arith(_tac) is now able to generate counterexamples for reals as well.
   435 
   436 * HOL-Algebra: new locale "ring" for non-commutative rings.
   437 
   438 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function
   439   definitions, thanks to Sava Krsti\'{c} and John Matthews.
   440 
   441 * HOL-Matrix: a first theory for matrices in HOL with an application of
   442   matrix theory to linear programming.
   443 
   444 * Unions and Intersections:
   445   The latex output syntax of UN and INT has been changed
   446   from "\Union x \in A. B" to "\Union_{x \in A} B"
   447   i.e. the index formulae has become a subscript.
   448   Similarly for "\Union x. B", and for \Inter instead of \Union.
   449 
   450 * Unions and Intersections over Intervals:
   451   There is new short syntax "UN i<=n. A" for "UN i:{0..n}. A". There is
   452   also an x-symbol version with subscripts "\<Union>\<^bsub>i <= n\<^esub>. A"
   453   like in normal math, and corresponding versions for < and for intersection.
   454 
   455 * ML: the legacy theory structures Int and List have been removed. They had
   456   conflicted with ML Basis Library structures having the same names.
   457 
   458 * 'refute' command added to search for (finite) countermodels.  Only works
   459   for a fragment of HOL.  The installation of an external SAT solver is
   460   highly recommended.  See "HOL/Refute.thy" for details.
   461 
   462 * 'quickcheck' command: Allows to find counterexamples by evaluating
   463   formulae under an assignment of free variables to random values.
   464   In contrast to 'refute', it can deal with inductive datatypes,
   465   but cannot handle quantifiers. See "HOL/ex/Quickcheck_Examples.thy"
   466   for examples.
   467 
   468 
   469 *** HOLCF ***
   470 
   471 * Streams now come with concatenation and are part of the HOLCF image
   472 
   473 
   474 
   475 New in Isabelle2003 (May 2003)
   476 ------------------------------
   477 
   478 *** General ***
   479 
   480 * Provers/simplifier:
   481 
   482   - Completely reimplemented method simp (ML: Asm_full_simp_tac):
   483     Assumptions are now subject to complete mutual simplification,
   484     not just from left to right. The simplifier now preserves
   485     the order of assumptions.
   486 
   487     Potential INCOMPATIBILITY:
   488 
   489     -- simp sometimes diverges where the old version did
   490        not, e.g. invoking simp on the goal
   491 
   492         [| P (f x); y = x; f x = f y |] ==> Q
   493 
   494        now gives rise to the infinite reduction sequence
   495 
   496         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...
   497 
   498        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this
   499        kind of problem.
   500 
   501     -- Tactics combining classical reasoner and simplification (such as auto)
   502        are also affected by this change, because many of them rely on
   503        simp. They may sometimes diverge as well or yield a different numbers
   504        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto
   505        in case of problems. Sometimes subsequent calls to the classical
   506        reasoner will fail because a preceeding call to the simplifier too
   507        eagerly simplified the goal, e.g. deleted redundant premises.
   508 
   509   - The simplifier trace now shows the names of the applied rewrite rules
   510 
   511   - You can limit the number of recursive invocations of the simplifier
   512     during conditional rewriting (where the simplifie tries to solve the
   513     conditions before applying the rewrite rule):
   514     ML "simp_depth_limit := n"
   515     where n is an integer. Thus you can force termination where previously
   516     the simplifier would diverge.
   517 
   518   - Accepts free variables as head terms in congruence rules.  Useful in Isar.
   519 
   520   - No longer aborts on failed congruence proof.  Instead, the
   521     congruence is ignored.
   522 
   523 * Pure: New generic framework for extracting programs from constructive
   524   proofs. See HOL/Extraction.thy for an example instantiation, as well
   525   as HOL/Extraction for some case studies.
   526 
   527 * Pure: The main goal of the proof state is no longer shown by default, only
   528 the subgoals. This behaviour is controlled by a new flag.
   529    PG menu: Isabelle/Isar -> Settings -> Show Main Goal
   530 (ML: Proof.show_main_goal).
   531 
   532 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all
   533 rules whose conclusion matches subgoal 1:
   534       PG menu: Isabelle/Isar -> Show me -> matching rules
   535 The rules are ordered by how closely they match the subgoal.
   536 In particular, rules that solve a subgoal outright are displayed first
   537 (or rather last, the way they are printed).
   538 (ML: ProofGeneral.print_intros())
   539 
   540 * Pure: New flag trace_unify_fail causes unification to print
   541 diagnostic information (PG: in trace buffer) when it fails. This is
   542 useful for figuring out why single step proofs like rule, erule or
   543 assumption failed.
   544 
   545 * Pure: Locale specifications now produce predicate definitions
   546 according to the body of text (covering assumptions modulo local
   547 definitions); predicate "loc_axioms" covers newly introduced text,
   548 while "loc" is cumulative wrt. all included locale expressions; the
   549 latter view is presented only on export into the global theory
   550 context; potential INCOMPATIBILITY, use "(open)" option to fall back
   551 on the old view without predicates;
   552 
   553 * Pure: predefined locales "var" and "struct" are useful for sharing
   554 parameters (as in CASL, for example); just specify something like
   555 ``var x + var y + struct M'' as import;
   556 
   557 * Pure: improved thms_containing: proper indexing of facts instead of
   558 raw theorems; check validity of results wrt. current name space;
   559 include local facts of proof configuration (also covers active
   560 locales), cover fixed variables in index; may use "_" in term
   561 specification; an optional limit for the number of printed facts may
   562 be given (the default is 40);
   563 
   564 * Pure: disallow duplicate fact bindings within new-style theory files
   565 (batch-mode only);
   566 
   567 * Provers: improved induct method: assumptions introduced by case
   568 "foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
   569 the goal statement); "foo" still refers to all facts collectively;
   570 
   571 * Provers: the function blast.overloaded has been removed: all constants
   572 are regarded as potentially overloaded, which improves robustness in exchange
   573 for slight decrease in efficiency;
   574 
   575 * Provers/linorder: New generic prover for transitivity reasoning over
   576 linear orders.  Note: this prover is not efficient!
   577 
   578 * Isar: preview of problems to finish 'show' now produce an error
   579 rather than just a warning (in interactive mode);
   580 
   581 
   582 *** HOL ***
   583 
   584 * arith(_tac)
   585 
   586  - Produces a counter example if it cannot prove a goal.
   587    Note that the counter example may be spurious if the goal is not a formula
   588    of quantifier-free linear arithmetic.
   589    In ProofGeneral the counter example appears in the trace buffer.
   590 
   591  - Knows about div k and mod k where k is a numeral of type nat or int.
   592 
   593  - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   594    linear arithmetic fails. This takes account of quantifiers and divisibility.
   595    Presburger arithmetic can also be called explicitly via presburger(_tac).
   596 
   597 * simp's arithmetic capabilities have been enhanced a bit: it now
   598 takes ~= in premises into account (by performing a case split);
   599 
   600 * simp reduces "m*(n div m) + n mod m" to n, even if the two summands
   601 are distributed over a sum of terms;
   602 
   603 * New tactic "trans_tac" and method "trans" instantiate
   604 Provers/linorder.ML for axclasses "order" and "linorder" (predicates
   605 "<=", "<" and "=").
   606 
   607 * function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main
   608 HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";
   609 
   610 * 'typedef' command has new option "open" to suppress the set
   611 definition;
   612 
   613 * functions Min and Max on finite sets have been introduced (theory
   614 Finite_Set);
   615 
   616 * attribute [symmetric] now works for relations as well; it turns
   617 (x,y) : R^-1 into (y,x) : R, and vice versa;
   618 
   619 * induct over a !!-quantified statement (say !!x1..xn):
   620   each "case" automatically performs "fix x1 .. xn" with exactly those names.
   621 
   622 * Map: `empty' is no longer a constant but a syntactic abbreviation for
   623 %x. None. Warning: empty_def now refers to the previously hidden definition
   624 of the empty set.
   625 
   626 * Algebra: formalization of classical algebra.  Intended as base for
   627 any algebraic development in Isabelle.  Currently covers group theory
   628 (up to Sylow's theorem) and ring theory (Universal Property of
   629 Univariate Polynomials).  Contributions welcome;
   630 
   631 * GroupTheory: deleted, since its material has been moved to Algebra;
   632 
   633 * Complex: new directory of the complex numbers with numeric constants,
   634 nonstandard complex numbers, and some complex analysis, standard and
   635 nonstandard (Jacques Fleuriot);
   636 
   637 * HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;
   638 
   639 * Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques
   640 Fleuriot);
   641 
   642 * Real/HahnBanach: updated and adapted to locales;
   643 
   644 * NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
   645 Gray and Kramer);
   646 
   647 * UNITY: added the Meier-Sanders theory of progress sets;
   648 
   649 * MicroJava: bytecode verifier and lightweight bytecode verifier
   650 as abstract algorithms, instantiated to the JVM;
   651 
   652 * Bali: Java source language formalization. Type system, operational
   653 semantics, axiomatic semantics. Supported language features:
   654 classes, interfaces, objects,virtual methods, static methods,
   655 static/instance fields, arrays, access modifiers, definite
   656 assignment, exceptions.
   657 
   658 
   659 *** ZF ***
   660 
   661 * ZF/Constructible: consistency proof for AC (Gdel's constructible
   662 universe, etc.);
   663 
   664 * Main ZF: virtually all theories converted to new-style format;
   665 
   666 
   667 *** ML ***
   668 
   669 * Pure: Tactic.prove provides sane interface for internal proofs;
   670 omits the infamous "standard" operation, so this is more appropriate
   671 than prove_goalw_cterm in many situations (e.g. in simprocs);
   672 
   673 * Pure: improved error reporting of simprocs;
   674 
   675 * Provers: Simplifier.simproc(_i) provides sane interface for setting
   676 up simprocs;
   677 
   678 
   679 *** Document preparation ***
   680 
   681 * uses \par instead of \\ for line breaks in theory text. This may
   682 shift some page breaks in large documents. To get the old behaviour
   683 use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.
   684 
   685 * minimized dependencies of isabelle.sty and isabellesym.sty on
   686 other packages
   687 
   688 * \<euro> now needs package babel/greek instead of marvosym (which
   689 broke \Rightarrow)
   690 
   691 * normal size for \<zero>...\<nine> (uses \mathbf instead of
   692 textcomp package)
   693 
   694 
   695 
   696 New in Isabelle2002 (March 2002)
   697 --------------------------------
   698 
   699 *** Document preparation ***
   700 
   701 * greatly simplified document preparation setup, including more
   702 graceful interpretation of isatool usedir -i/-d/-D options, and more
   703 instructive isatool mkdir; users should basically be able to get
   704 started with "isatool mkdir HOL Test && isatool make"; alternatively,
   705 users may run a separate document processing stage manually like this:
   706 "isatool usedir -D output HOL Test && isatool document Test/output";
   707 
   708 * theory dependency graph may now be incorporated into documents;
   709 isatool usedir -g true will produce session_graph.eps/.pdf for use
   710 with \includegraphics of LaTeX;
   711 
   712 * proper spacing of consecutive markup elements, especially text
   713 blocks after section headings;
   714 
   715 * support bold style (for single symbols only), input syntax is like
   716 this: "\<^bold>\<alpha>" or "\<^bold>A";
   717 
   718 * \<bullet> is now output as bold \cdot by default, which looks much
   719 better in printed text;
   720 
   721 * added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
   722 note that these symbols are currently unavailable in Proof General /
   723 X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;
   724 
   725 * isatool latex no longer depends on changed TEXINPUTS, instead
   726 isatool document copies the Isabelle style files to the target
   727 location;
   728 
   729 
   730 *** Isar ***
   731 
   732 * Pure/Provers: improved proof by cases and induction;
   733   - 'case' command admits impromptu naming of parameters (such as
   734     "case (Suc n)");
   735   - 'induct' method divinates rule instantiation from the inductive
   736     claim; no longer requires excessive ?P bindings for proper
   737     instantiation of cases;
   738   - 'induct' method properly enumerates all possibilities of set/type
   739     rules; as a consequence facts may be also passed through *type*
   740     rules without further ado;
   741   - 'induct' method now derives symbolic cases from the *rulified*
   742     rule (before it used to rulify cases stemming from the internal
   743     atomized version); this means that the context of a non-atomic
   744     statement becomes is included in the hypothesis, avoiding the
   745     slightly cumbersome show "PROP ?case" form;
   746   - 'induct' may now use elim-style induction rules without chaining
   747     facts, using ``missing'' premises from the goal state; this allows
   748     rules stemming from inductive sets to be applied in unstructured
   749     scripts, while still benefitting from proper handling of non-atomic
   750     statements; NB: major inductive premises need to be put first, all
   751     the rest of the goal is passed through the induction;
   752   - 'induct' proper support for mutual induction involving non-atomic
   753     rule statements (uses the new concept of simultaneous goals, see
   754     below);
   755   - append all possible rule selections, but only use the first
   756     success (no backtracking);
   757   - removed obsolete "(simplified)" and "(stripped)" options of methods;
   758   - undeclared rule case names default to numbers 1, 2, 3, ...;
   759   - added 'print_induct_rules' (covered by help item in recent Proof
   760     General versions);
   761   - moved induct/cases attributes to Pure, methods to Provers;
   762   - generic method setup instantiated for FOL and HOL;
   763 
   764 * Pure: support multiple simultaneous goal statements, for example
   765 "have a: A and b: B" (same for 'theorem' etc.); being a pure
   766 meta-level mechanism, this acts as if several individual goals had
   767 been stated separately; in particular common proof methods need to be
   768 repeated in order to cover all claims; note that a single elimination
   769 step is *not* sufficient to establish the two conjunctions, so this
   770 fails:
   771 
   772   assume "A & B" then have A and B ..   (*".." fails*)
   773 
   774 better use "obtain" in situations as above; alternative refer to
   775 multi-step methods like 'auto', 'simp_all', 'blast+' etc.;
   776 
   777 * Pure: proper integration with ``locales''; unlike the original
   778 version by Florian Kammller, Isar locales package high-level proof
   779 contexts rather than raw logical ones (e.g. we admit to include
   780 attributes everywhere); operations on locales include merge and
   781 rename; support for implicit arguments (``structures''); simultaneous
   782 type-inference over imports and text; see also HOL/ex/Locales.thy for
   783 some examples;
   784 
   785 * Pure: the following commands have been ``localized'', supporting a
   786 target locale specification "(in name)": 'lemma', 'theorem',
   787 'corollary', 'lemmas', 'theorems', 'declare'; the results will be
   788 stored both within the locale and at the theory level (exported and
   789 qualified by the locale name);
   790 
   791 * Pure: theory goals may now be specified in ``long'' form, with
   792 ad-hoc contexts consisting of arbitrary locale elements. for example
   793 ``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
   794 definitions may be given, too); the result is a meta-level rule with
   795 the context elements being discharged in the obvious way;
   796 
   797 * Pure: new proof command 'using' allows to augment currently used
   798 facts after a goal statement ('using' is syntactically analogous to
   799 'apply', but acts on the goal's facts only); this allows chained facts
   800 to be separated into parts given before and after a claim, as in
   801 ``from a and b have C using d and e <proof>'';
   802 
   803 * Pure: renamed "antecedent" case to "rule_context";
   804 
   805 * Pure: new 'judgment' command records explicit information about the
   806 object-logic embedding (used by several tools internally); no longer
   807 use hard-wired "Trueprop";
   808 
   809 * Pure: added 'corollary' command;
   810 
   811 * Pure: fixed 'token_translation' command;
   812 
   813 * Pure: removed obsolete 'exported' attribute;
   814 
   815 * Pure: dummy pattern "_" in is/let is now automatically lifted over
   816 bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
   817 supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");
   818 
   819 * Pure: method 'atomize' presents local goal premises as object-level
   820 statements (atomic meta-level propositions); setup controlled via
   821 rewrite rules declarations of 'atomize' attribute; example
   822 application: 'induct' method with proper rule statements in improper
   823 proof *scripts*;
   824 
   825 * Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
   826 now consider the syntactic context of assumptions, giving a better
   827 chance to get type-inference of the arguments right (this is
   828 especially important for locales);
   829 
   830 * Pure: "sorry" no longer requires quick_and_dirty in interactive
   831 mode;
   832 
   833 * Pure/obtain: the formal conclusion "thesis", being marked as
   834 ``internal'', may no longer be reference directly in the text;
   835 potential INCOMPATIBILITY, may need to use "?thesis" in rare
   836 situations;
   837 
   838 * Pure: generic 'sym' attribute which declares a rule both as pure
   839 'elim?' and for the 'symmetric' operation;
   840 
   841 * Pure: marginal comments ``--'' may now occur just anywhere in the
   842 text; the fixed correlation with particular command syntax has been
   843 discontinued;
   844 
   845 * Pure: new method 'rules' is particularly well-suited for proof
   846 search in intuitionistic logic; a bit slower than 'blast' or 'fast',
   847 but often produces more compact proof terms with less detours;
   848 
   849 * Pure/Provers/classical: simplified integration with pure rule
   850 attributes and methods; the classical "intro?/elim?/dest?"
   851 declarations coincide with the pure ones; the "rule" method no longer
   852 includes classically swapped intros; "intro" and "elim" methods no
   853 longer pick rules from the context; also got rid of ML declarations
   854 AddXIs/AddXEs/AddXDs; all of this has some potential for
   855 INCOMPATIBILITY;
   856 
   857 * Provers/classical: attribute 'swapped' produces classical inversions
   858 of introduction rules;
   859 
   860 * Provers/simplifier: 'simplified' attribute may refer to explicit
   861 rules instead of full simplifier context; 'iff' attribute handles
   862 conditional rules;
   863 
   864 * HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;
   865 
   866 * HOL: 'recdef' now fails on unfinished automated proofs, use
   867 "(permissive)" option to recover old behavior;
   868 
   869 * HOL: 'inductive' no longer features separate (collective) attributes
   870 for 'intros' (was found too confusing);
   871 
   872 * HOL: properly declared induction rules less_induct and
   873 wf_induct_rule;
   874 
   875 
   876 *** HOL ***
   877 
   878 * HOL: moved over to sane numeral syntax; the new policy is as
   879 follows:
   880 
   881   - 0 and 1 are polymorphic constants, which are defined on any
   882   numeric type (nat, int, real etc.);
   883 
   884   - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
   885   binary representation internally;
   886 
   887   - type nat has special constructor Suc, and generally prefers Suc 0
   888   over 1::nat and Suc (Suc 0) over 2::nat;
   889 
   890 This change may cause significant problems of INCOMPATIBILITY; here
   891 are some hints on converting existing sources:
   892 
   893   - due to the new "num" token, "-0" and "-1" etc. are now atomic
   894   entities, so expressions involving "-" (unary or binary minus) need
   895   to be spaced properly;
   896 
   897   - existing occurrences of "1" may need to be constraint "1::nat" or
   898   even replaced by Suc 0; similar for old "2";
   899 
   900   - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";
   901 
   902   - remove all special provisions on numerals in proofs;
   903 
   904 * HOL: simp rules nat_number expand numerals on nat to Suc/0
   905 representation (depends on bin_arith_simps in the default context);
   906 
   907 * HOL: symbolic syntax for x^2 (numeral 2);
   908 
   909 * HOL: the class of all HOL types is now called "type" rather than
   910 "term"; INCOMPATIBILITY, need to adapt references to this type class
   911 in axclass/classes, instance/arities, and (usually rare) occurrences
   912 in typings (of consts etc.); internally the class is called
   913 "HOL.type", ML programs should refer to HOLogic.typeS;
   914 
   915 * HOL/record package improvements:
   916   - new derived operations "fields" to build a partial record section,
   917     "extend" to promote a fixed record to a record scheme, and
   918     "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
   919     declared as simp by default;
   920   - shared operations ("more", "fields", etc.) now need to be always
   921     qualified) --- potential INCOMPATIBILITY;
   922   - removed "make_scheme" operations (use "make" with "extend") --
   923     INCOMPATIBILITY;
   924   - removed "more" class (simply use "term") -- INCOMPATIBILITY;
   925   - provides cases/induct rules for use with corresponding Isar
   926     methods (for concrete records, record schemes, concrete more
   927     parts, and schematic more parts -- in that order);
   928   - internal definitions directly based on a light-weight abstract
   929     theory of product types over typedef rather than datatype;
   930 
   931 * HOL: generic code generator for generating executable ML code from
   932 specifications; specific support for HOL constructs such as inductive
   933 datatypes and sets, as well as recursive functions; can be invoked
   934 via 'generate_code' theory section;
   935 
   936 * HOL: canonical cases/induct rules for n-tuples (n = 3..7);
   937 
   938 * HOL: consolidated and renamed several theories.  In particular:
   939         Ord.thy has been absorbed into HOL.thy
   940         String.thy has been absorbed into List.thy
   941 
   942 * HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
   943 (beware of argument permutation!);
   944 
   945 * HOL: linorder_less_split superseded by linorder_cases;
   946 
   947 * HOL/List: "nodups" renamed to "distinct";
   948 
   949 * HOL: added "The" definite description operator; move Hilbert's "Eps"
   950 to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
   951   - Ex_def has changed, now need to use some_eq_ex
   952 
   953 * HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
   954 in this (rare) case use:
   955 
   956   delSWrapper "split_all_tac"
   957   addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)
   958 
   959 * HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
   960 MAY FAIL;
   961 
   962 * HOL: introduced f^n = f o ... o f; warning: due to the limits of
   963 Isabelle's type classes, ^ on functions and relations has too general
   964 a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
   965 necessary to attach explicit type constraints;
   966 
   967 * HOL/Relation: the prefix name of the infix "O" has been changed from
   968 "comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
   969 renamed accordingly (eg "compI" -> "rel_compI").
   970 
   971 * HOL: syntax translations now work properly with numerals and records
   972 expressions;
   973 
   974 * HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
   975 of "lam" -- INCOMPATIBILITY;
   976 
   977 * HOL: got rid of some global declarations (potential INCOMPATIBILITY
   978 for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
   979 renamed "Product_Type.unit";
   980 
   981 * HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl
   982 
   983 * HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
   984 the "cases" method);
   985 
   986 * HOL/GroupTheory: group theory examples including Sylow's theorem (by
   987 Florian Kammller);
   988 
   989 * HOL/IMP: updated and converted to new-style theory format; several
   990 parts turned into readable document, with proper Isar proof texts and
   991 some explanations (by Gerwin Klein);
   992 
   993 * HOL-Real: added Complex_Numbers (by Gertrud Bauer);
   994 
   995 * HOL-Hyperreal is now a logic image;
   996 
   997 
   998 *** HOLCF ***
   999 
  1000 * Isar: consts/constdefs supports mixfix syntax for continuous
  1001 operations;
  1002 
  1003 * Isar: domain package adapted to new-style theory format, e.g. see
  1004 HOLCF/ex/Dnat.thy;
  1005 
  1006 * theory Lift: proper use of rep_datatype lift instead of ML hacks --
  1007 potential INCOMPATIBILITY; now use plain induct_tac instead of former
  1008 lift.induct_tac, always use UU instead of Undef;
  1009 
  1010 * HOLCF/IMP: updated and converted to new-style theory;
  1011 
  1012 
  1013 *** ZF ***
  1014 
  1015 * Isar: proper integration of logic-specific tools and packages,
  1016 including theory commands '(co)inductive', '(co)datatype',
  1017 'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
  1018 'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');
  1019 
  1020 * theory Main no longer includes AC; for the Axiom of Choice, base
  1021 your theory on Main_ZFC;
  1022 
  1023 * the integer library now covers quotients and remainders, with many
  1024 laws relating division to addition, multiplication, etc.;
  1025 
  1026 * ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
  1027 typeless version of the formalism;
  1028 
  1029 * ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
  1030 format;
  1031 
  1032 * ZF/Induct: new directory for examples of inductive definitions,
  1033 including theory Multiset for multiset orderings; converted to
  1034 new-style theory format;
  1035 
  1036 * ZF: many new theorems about lists, ordinals, etc.;
  1037 
  1038 
  1039 *** General ***
  1040 
  1041 * Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
  1042 variable proof controls level of detail: 0 = no proofs (only oracle
  1043 dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
  1044 also ref manual for further ML interfaces;
  1045 
  1046 * Pure/axclass: removed obsolete ML interface
  1047 goal_subclass/goal_arity;
  1048 
  1049 * Pure/syntax: new token syntax "num" for plain numerals (without "#"
  1050 of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
  1051 separate tokens, so expressions involving minus need to be spaced
  1052 properly;
  1053 
  1054 * Pure/syntax: support non-oriented infixes, using keyword "infix"
  1055 rather than "infixl" or "infixr";
  1056 
  1057 * Pure/syntax: concrete syntax for dummy type variables admits genuine
  1058 sort constraint specifications in type inference; e.g. "x::_::foo"
  1059 ensures that the type of "x" is of sort "foo" (but not necessarily a
  1060 type variable);
  1061 
  1062 * Pure/syntax: print modes "type_brackets" and "no_type_brackets"
  1063 control output of nested => (types); the default behavior is
  1064 "type_brackets";
  1065 
  1066 * Pure/syntax: builtin parse translation for "_constify" turns valued
  1067 tokens into AST constants;
  1068 
  1069 * Pure/syntax: prefer later declarations of translations and print
  1070 translation functions; potential INCOMPATIBILITY: need to reverse
  1071 multiple declarations for same syntax element constant;
  1072 
  1073 * Pure/show_hyps reset by default (in accordance to existing Isar
  1074 practice);
  1075 
  1076 * Provers/classical: renamed addaltern to addafter, addSaltern to
  1077 addSafter;
  1078 
  1079 * Provers/clasimp: ``iff'' declarations now handle conditional rules
  1080 as well;
  1081 
  1082 * system: tested support for MacOS X; should be able to get Isabelle +
  1083 Proof General to work in a plain Terminal after installing Poly/ML
  1084 (e.g. from the Isabelle distribution area) and GNU bash alone
  1085 (e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
  1086 support requires further installations, e.g. from
  1087 http://fink.sourceforge.net/);
  1088 
  1089 * system: support Poly/ML 4.1.1 (able to manage larger heaps);
  1090 
  1091 * system: reduced base memory usage by Poly/ML (approx. 20 MB instead
  1092 of 40 MB), cf. ML_OPTIONS;
  1093 
  1094 * system: Proof General keywords specification is now part of the
  1095 Isabelle distribution (see etc/isar-keywords.el);
  1096 
  1097 * system: support for persistent Proof General sessions (refrain from
  1098 outdating all loaded theories on startup); user may create writable
  1099 logic images like this: ``isabelle -q HOL Test'';
  1100 
  1101 * system: smart selection of Isabelle process versus Isabelle
  1102 interface, accommodates case-insensitive file systems (e.g. HFS+); may
  1103 run both "isabelle" and "Isabelle" even if file names are badly
  1104 damaged (executable inspects the case of the first letter of its own
  1105 name); added separate "isabelle-process" and "isabelle-interface";
  1106 
  1107 * system: refrain from any attempt at filtering input streams; no
  1108 longer support ``8bit'' encoding of old isabelle font, instead proper
  1109 iso-latin characters may now be used; the related isatools
  1110 "symbolinput" and "nonascii" have disappeared as well;
  1111 
  1112 * system: removed old "xterm" interface (the print modes "xterm" and
  1113 "xterm_color" are still available for direct use in a suitable
  1114 terminal);
  1115 
  1116 
  1117 
  1118 New in Isabelle99-2 (February 2001)
  1119 -----------------------------------
  1120 
  1121 *** Overview of INCOMPATIBILITIES ***
  1122 
  1123 * HOL: please note that theories in the Library and elsewhere often use the
  1124 new-style (Isar) format; to refer to their theorems in an ML script you must
  1125 bind them to ML identifers by e.g.      val thm_name = thm "thm_name";
  1126 
  1127 * HOL: inductive package no longer splits induction rule aggressively,
  1128 but only as far as specified by the introductions given; the old
  1129 format may be recovered via ML function complete_split_rule or attribute
  1130 'split_rule (complete)';
  1131 
  1132 * HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
  1133 gfp_Tarski to gfp_unfold;
  1134 
  1135 * HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;
  1136 
  1137 * HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
  1138 relation); infix "^^" has been renamed "``"; infix "``" has been
  1139 renamed "`"; "univalent" has been renamed "single_valued";
  1140 
  1141 * HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
  1142 operation;
  1143 
  1144 * HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;
  1145 
  1146 * Isar: 'obtain' no longer declares "that" fact as simp/intro;
  1147 
  1148 * Isar/HOL: method 'induct' now handles non-atomic goals; as a
  1149 consequence, it is no longer monotonic wrt. the local goal context
  1150 (which is now passed through the inductive cases);
  1151 
  1152 * Document preparation: renamed standard symbols \<ll> to \<lless> and
  1153 \<gg> to \<ggreater>;
  1154 
  1155 
  1156 *** Document preparation ***
  1157 
  1158 * \isabellestyle{NAME} selects version of Isabelle output (currently
  1159 available: are "it" for near math-mode best-style output, "sl" for
  1160 slanted text style, and "tt" for plain type-writer; if no
  1161 \isabellestyle command is given, output is according to slanted
  1162 type-writer);
  1163 
  1164 * support sub/super scripts (for single symbols only), input syntax is
  1165 like this: "A\<^sup>*" or "A\<^sup>\<star>";
  1166 
  1167 * some more standard symbols; see Appendix A of the system manual for
  1168 the complete list of symbols defined in isabellesym.sty;
  1169 
  1170 * improved isabelle style files; more abstract symbol implementation
  1171 (should now use \isamath{...} and \isatext{...} in custom symbol
  1172 definitions);
  1173 
  1174 * antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
  1175 state; Note that presentation of goal states does not conform to
  1176 actual human-readable proof documents.  Please do not include goal
  1177 states into document output unless you really know what you are doing!
  1178 
  1179 * proper indentation of antiquoted output with proportional LaTeX
  1180 fonts;
  1181 
  1182 * no_document ML operator temporarily disables LaTeX document
  1183 generation;
  1184 
  1185 * isatool unsymbolize tunes sources for plain ASCII communication;
  1186 
  1187 
  1188 *** Isar ***
  1189 
  1190 * Pure: Isar now suffers initial goal statements to contain unbound
  1191 schematic variables (this does not conform to actual readable proof
  1192 documents, due to unpredictable outcome and non-compositional proof
  1193 checking); users who know what they are doing may use schematic goals
  1194 for Prolog-style synthesis of proven results;
  1195 
  1196 * Pure: assumption method (an implicit finishing) now handles actual
  1197 rules as well;
  1198 
  1199 * Pure: improved 'obtain' --- moved to Pure, insert "that" into
  1200 initial goal, declare "that" only as Pure intro (only for single
  1201 steps); the "that" rule assumption may now be involved in implicit
  1202 finishing, thus ".." becomes a feasible for trivial obtains;
  1203 
  1204 * Pure: default proof step now includes 'intro_classes'; thus trivial
  1205 instance proofs may be performed by "..";
  1206 
  1207 * Pure: ?thesis / ?this / "..." now work for pure meta-level
  1208 statements as well;
  1209 
  1210 * Pure: more robust selection of calculational rules;
  1211 
  1212 * Pure: the builtin notion of 'finished' goal now includes the ==-refl
  1213 rule (as well as the assumption rule);
  1214 
  1215 * Pure: 'thm_deps' command visualizes dependencies of theorems and
  1216 lemmas, using the graph browser tool;
  1217 
  1218 * Pure: predict failure of "show" in interactive mode;
  1219 
  1220 * Pure: 'thms_containing' now takes actual terms as arguments;
  1221 
  1222 * HOL: improved method 'induct' --- now handles non-atomic goals
  1223 (potential INCOMPATIBILITY); tuned error handling;
  1224 
  1225 * HOL: cases and induct rules now provide explicit hints about the
  1226 number of facts to be consumed (0 for "type" and 1 for "set" rules);
  1227 any remaining facts are inserted into the goal verbatim;
  1228 
  1229 * HOL: local contexts (aka cases) may now contain term bindings as
  1230 well; the 'cases' and 'induct' methods new provide a ?case binding for
  1231 the result to be shown in each case;
  1232 
  1233 * HOL: added 'recdef_tc' command;
  1234 
  1235 * isatool convert assists in eliminating legacy ML scripts;
  1236 
  1237 
  1238 *** HOL ***
  1239 
  1240 * HOL/Library: a collection of generic theories to be used together
  1241 with main HOL; the theory loader path already includes this directory
  1242 by default; the following existing theories have been moved here:
  1243 HOL/Induct/Multiset, HOL/Induct/Acc (as Accessible_Part), HOL/While
  1244 (as While_Combinator), HOL/Lex/Prefix (as List_Prefix);
  1245 
  1246 * HOL/Unix: "Some aspects of Unix file-system security", a typical
  1247 modelling and verification task performed in Isabelle/HOL +
  1248 Isabelle/Isar + Isabelle document preparation (by Markus Wenzel).
  1249 
  1250 * HOL/Algebra: special summation operator SUM no longer exists, it has
  1251 been replaced by setsum; infix 'assoc' now has priority 50 (like
  1252 'dvd'); axiom 'one_not_zero' has been moved from axclass 'ring' to
  1253 'domain', this makes the theory consistent with mathematical
  1254 literature;
  1255 
  1256 * HOL basics: added overloaded operations "inverse" and "divide"
  1257 (infix "/"), syntax for generic "abs" operation, generic summation
  1258 operator \<Sum>;
  1259 
  1260 * HOL/typedef: simplified package, provide more useful rules (see also
  1261 HOL/subset.thy);
  1262 
  1263 * HOL/datatype: induction rule for arbitrarily branching datatypes is
  1264 now expressed as a proper nested rule (old-style tactic scripts may
  1265 require atomize_strip_tac to cope with non-atomic premises);
  1266 
  1267 * HOL: renamed theory "Prod" to "Product_Type", renamed "split" rule
  1268 to "split_conv" (old name still available for compatibility);
  1269 
  1270 * HOL: improved concrete syntax for strings (e.g. allows translation
  1271 rules with string literals);
  1272 
  1273 * HOL-Real-Hyperreal: this extends HOL-Real with the hyperreals
  1274  and Fleuriot's mechanization of analysis, including the transcendental
  1275  functions for the reals;
  1276 
  1277 * HOL/Real, HOL/Hyperreal: improved arithmetic simplification;
  1278 
  1279 
  1280 *** CTT ***
  1281 
  1282 * CTT: x-symbol support for Pi, Sigma, -->, : (membership); note that
  1283 "lam" is displayed as TWO lambda-symbols
  1284 
  1285 * CTT: theory Main now available, containing everything (that is, Bool
  1286 and Arith);
  1287 
  1288 
  1289 *** General ***
  1290 
  1291 * Pure: the Simplifier has been implemented properly as a derived rule
  1292 outside of the actual kernel (at last!); the overall performance
  1293 penalty in practical applications is about 50%, while reliability of
  1294 the Isabelle inference kernel has been greatly improved;
  1295 
  1296 * print modes "brackets" and "no_brackets" control output of nested =>
  1297 (types) and ==> (props); the default behaviour is "brackets";
  1298 
  1299 * Provers: fast_tac (and friends) now handle actual object-logic rules
  1300 as assumptions as well;
  1301 
  1302 * system: support Poly/ML 4.0;
  1303 
  1304 * system: isatool install handles KDE version 1 or 2;
  1305 
  1306 
  1307 
  1308 New in Isabelle99-1 (October 2000)
  1309 ----------------------------------
  1310 
  1311 *** Overview of INCOMPATIBILITIES ***
  1312 
  1313 * HOL: simplification of natural numbers is much changed; to partly
  1314 recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)
  1315 issue the following ML commands:
  1316 
  1317   Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;
  1318   Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];
  1319 
  1320 * HOL: simplification no longer dives into case-expressions; this is
  1321 controlled by "t.weak_case_cong" for each datatype t;
  1322 
  1323 * HOL: nat_less_induct renamed to less_induct;
  1324 
  1325 * HOL: systematic renaming of the SOME (Eps) rules, may use isatool
  1326 fixsome to patch .thy and .ML sources automatically;
  1327 
  1328   select_equality  -> some_equality
  1329   select_eq_Ex     -> some_eq_ex
  1330   selectI2EX       -> someI2_ex
  1331   selectI2         -> someI2
  1332   selectI          -> someI
  1333   select1_equality -> some1_equality
  1334   Eps_sym_eq       -> some_sym_eq_trivial
  1335   Eps_eq           -> some_eq_trivial
  1336 
  1337 * HOL: exhaust_tac on datatypes superceded by new generic case_tac;
  1338 
  1339 * HOL: removed obsolete theorem binding expand_if (refer to split_if
  1340 instead);
  1341 
  1342 * HOL: the recursion equations generated by 'recdef' are now called
  1343 f.simps instead of f.rules;
  1344 
  1345 * HOL: qed_spec_mp now also handles bounded ALL as well;
  1346 
  1347 * HOL: 0 is now overloaded, so the type constraint ":: nat" may
  1348 sometimes be needed;
  1349 
  1350 * HOL: the constant for "f``x" is now "image" rather than "op ``";
  1351 
  1352 * HOL: the constant for "f-``x" is now "vimage" rather than "op -``";
  1353 
  1354 * HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian
  1355 product is now "<*>" instead of "Times"; the lexicographic product is
  1356 now "<*lex*>" instead of "**";
  1357 
  1358 * HOL: theory Sexp is now in HOL/Induct examples (it used to be part
  1359 of main HOL, but was unused); better use HOL's datatype package;
  1360 
  1361 * HOL: removed "symbols" syntax for constant "override" of theory Map;
  1362 the old syntax may be recovered as follows:
  1363 
  1364   syntax (symbols)
  1365     override  :: "('a ~=> 'b) => ('a ~=> 'b) => ('a ~=> 'b)"
  1366       (infixl "\\<oplus>" 100)
  1367 
  1368 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1369 
  1370 * HOL/ML: even fewer consts are declared as global (see theories Ord,
  1371 Lfp, Gfp, WF); this only affects ML packages that refer to const names
  1372 internally;
  1373 
  1374 * HOL and ZF: syntax for quotienting wrt an equivalence relation
  1375 changed from A/r to A//r;
  1376 
  1377 * ZF: new treatment of arithmetic (nat & int) may break some old
  1378 proofs;
  1379 
  1380 * Isar: renamed some attributes (RS -> THEN, simplify -> simplified,
  1381 rulify -> rule_format, elimify -> elim_format, ...);
  1382 
  1383 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1384 intro/intro!/intro!! flags to intro!/intro/intro? (in most cases, one
  1385 should have to change intro!! to intro? only); replaced "delrule" by
  1386 "rule del";
  1387 
  1388 * Isar/HOL: renamed "intrs" to "intros" in inductive definitions;
  1389 
  1390 * Provers: strengthened force_tac by using new first_best_tac;
  1391 
  1392 * LaTeX document preparation: several changes of isabelle.sty (see
  1393 lib/texinputs);
  1394 
  1395 
  1396 *** Document preparation ***
  1397 
  1398 * formal comments (text blocks etc.) in new-style theories may now
  1399 contain antiquotations of thm/prop/term/typ/text to be presented
  1400 according to latex print mode; concrete syntax is like this:
  1401 @{term[show_types] "f(x) = a + x"};
  1402 
  1403 * isatool mkdir provides easy setup of Isabelle session directories,
  1404 including proper document sources;
  1405 
  1406 * generated LaTeX sources are now deleted after successful run
  1407 (isatool document -c); may retain a copy somewhere else via -D option
  1408 of isatool usedir;
  1409 
  1410 * isatool usedir -D now lets isatool latex -o sty update the Isabelle
  1411 style files, achieving self-contained LaTeX sources and simplifying
  1412 LaTeX debugging;
  1413 
  1414 * old-style theories now produce (crude) LaTeX output as well;
  1415 
  1416 * browser info session directories are now self-contained (may be put
  1417 on WWW server seperately); improved graphs of nested sessions; removed
  1418 graph for 'all sessions';
  1419 
  1420 * several improvements in isabelle style files; \isabellestyle{it}
  1421 produces fake math mode output; \isamarkupheader is now \section by
  1422 default; see lib/texinputs/isabelle.sty etc.;
  1423 
  1424 
  1425 *** Isar ***
  1426 
  1427 * Isar/Pure: local results and corresponding term bindings are now
  1428 subject to Hindley-Milner polymorphism (similar to ML); this
  1429 accommodates incremental type-inference very nicely;
  1430 
  1431 * Isar/Pure: new derived language element 'obtain' supports
  1432 generalized existence reasoning;
  1433 
  1434 * Isar/Pure: new calculational elements 'moreover' and 'ultimately'
  1435 support accumulation of results, without applying any rules yet;
  1436 useful to collect intermediate results without explicit name
  1437 references, and for use with transitivity rules with more than 2
  1438 premises;
  1439 
  1440 * Isar/Pure: scalable support for case-analysis type proofs: new
  1441 'case' language element refers to local contexts symbolically, as
  1442 produced by certain proof methods; internally, case names are attached
  1443 to theorems as "tags";
  1444 
  1445 * Isar/Pure: theory command 'hide' removes declarations from
  1446 class/type/const name spaces;
  1447 
  1448 * Isar/Pure: theory command 'defs' supports option "(overloaded)" to
  1449 indicate potential overloading;
  1450 
  1451 * Isar/Pure: changed syntax of local blocks from {{ }} to { };
  1452 
  1453 * Isar/Pure: syntax of sorts made 'inner', i.e. have to write
  1454 "{a,b,c}" instead of {a,b,c};
  1455 
  1456 * Isar/Pure now provides its own version of intro/elim/dest
  1457 attributes; useful for building new logics, but beware of confusion
  1458 with the version in Provers/classical;
  1459 
  1460 * Isar/Pure: the local context of (non-atomic) goals is provided via
  1461 case name 'antecedent';
  1462 
  1463 * Isar/Pure: removed obsolete 'transfer' attribute (transfer of thms
  1464 to the current context is now done automatically);
  1465 
  1466 * Isar/Pure: theory command 'method_setup' provides a simple interface
  1467 for definining proof methods in ML;
  1468 
  1469 * Isar/Provers: intro/elim/dest attributes changed; renamed
  1470 intro/intro!/intro!! flags to intro!/intro/intro? (INCOMPATIBILITY, in
  1471 most cases, one should have to change intro!! to intro? only);
  1472 replaced "delrule" by "rule del";
  1473 
  1474 * Isar/Provers: new 'hypsubst' method, plain 'subst' method and
  1475 'symmetric' attribute (the latter supercedes [RS sym]);
  1476 
  1477 * Isar/Provers: splitter support (via 'split' attribute and 'simp'
  1478 method modifier); 'simp' method: 'only:' modifier removes loopers as
  1479 well (including splits);
  1480 
  1481 * Isar/Provers: Simplifier and Classical methods now support all kind
  1482 of modifiers used in the past, including 'cong', 'iff', etc.
  1483 
  1484 * Isar/Provers: added 'fastsimp' and 'clarsimp' methods (combination
  1485 of Simplifier and Classical reasoner);
  1486 
  1487 * Isar/HOL: new proof method 'cases' and improved version of 'induct'
  1488 now support named cases; major packages (inductive, datatype, primrec,
  1489 recdef) support case names and properly name parameters;
  1490 
  1491 * Isar/HOL: new transitivity rules for substitution in inequalities --
  1492 monotonicity conditions are extracted to be proven at end of
  1493 calculations;
  1494 
  1495 * Isar/HOL: removed 'case_split' thm binding, should use 'cases' proof
  1496 method anyway;
  1497 
  1498 * Isar/HOL: removed old expand_if = split_if; theorems if_splits =
  1499 split_if split_if_asm; datatype package provides theorems foo.splits =
  1500 foo.split foo.split_asm for each datatype;
  1501 
  1502 * Isar/HOL: tuned inductive package, rename "intrs" to "intros"
  1503 (potential INCOMPATIBILITY), emulation of mk_cases feature for proof
  1504 scripts: new 'inductive_cases' command and 'ind_cases' method; (Note:
  1505 use "(cases (simplified))" method in proper proof texts);
  1506 
  1507 * Isar/HOL: added global 'arith_split' attribute for 'arith' method;
  1508 
  1509 * Isar: names of theorems etc. may be natural numbers as well;
  1510 
  1511 * Isar: 'pr' command: optional arguments for goals_limit and
  1512 ProofContext.prems_limit; no longer prints theory contexts, but only
  1513 proof states;
  1514 
  1515 * Isar: diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit
  1516 additional print modes to be specified; e.g. "pr(latex)" will print
  1517 proof state according to the Isabelle LaTeX style;
  1518 
  1519 * Isar: improved support for emulating tactic scripts, including proof
  1520 methods 'rule_tac' etc., 'cut_tac', 'thin_tac', 'subgoal_tac',
  1521 'rename_tac', 'rotate_tac', 'tactic', and 'case_tac' / 'induct_tac'
  1522 (for HOL datatypes);
  1523 
  1524 * Isar: simplified (more robust) goal selection of proof methods: 1st
  1525 goal, all goals, or explicit goal specifier (tactic emulation); thus
  1526 'proof method scripts' have to be in depth-first order;
  1527 
  1528 * Isar: tuned 'let' syntax: replaced 'as' keyword by 'and';
  1529 
  1530 * Isar: removed 'help' command, which hasn't been too helpful anyway;
  1531 should instead use individual commands for printing items
  1532 (print_commands, print_methods etc.);
  1533 
  1534 * Isar: added 'nothing' --- the empty list of theorems;
  1535 
  1536 
  1537 *** HOL ***
  1538 
  1539 * HOL/MicroJava: formalization of a fragment of Java, together with a
  1540 corresponding virtual machine and a specification of its bytecode
  1541 verifier and a lightweight bytecode verifier, including proofs of
  1542 type-safety; by Gerwin Klein, Tobias Nipkow, David von Oheimb, and
  1543 Cornelia Pusch (see also the homepage of project Bali at
  1544 http://isabelle.in.tum.de/Bali/);
  1545 
  1546 * HOL/Algebra: new theory of rings and univariate polynomials, by
  1547 Clemens Ballarin;
  1548 
  1549 * HOL/NumberTheory: fundamental Theorem of Arithmetic, Chinese
  1550 Remainder Theorem, Fermat/Euler Theorem, Wilson's Theorem, by Thomas M
  1551 Rasmussen;
  1552 
  1553 * HOL/Lattice: fundamental concepts of lattice theory and order
  1554 structures, including duals, properties of bounds versus algebraic
  1555 laws, lattice operations versus set-theoretic ones, the Knaster-Tarski
  1556 Theorem for complete lattices etc.; may also serve as a demonstration
  1557 for abstract algebraic reasoning using axiomatic type classes, and
  1558 mathematics-style proof in Isabelle/Isar; by Markus Wenzel;
  1559 
  1560 * HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog, by David
  1561 von Oheimb;
  1562 
  1563 * HOL/IMPP: extension of IMP with local variables and mutually
  1564 recursive procedures, by David von Oheimb;
  1565 
  1566 * HOL/Lambda: converted into new-style theory and document;
  1567 
  1568 * HOL/ex/Multiquote: example of multiple nested quotations and
  1569 anti-quotations -- basically a generalized version of de-Bruijn
  1570 representation; very useful in avoiding lifting of operations;
  1571 
  1572 * HOL/record: added general record equality rule to simpset; fixed
  1573 select-update simplification procedure to handle extended records as
  1574 well; admit "r" as field name;
  1575 
  1576 * HOL: 0 is now overloaded over the new sort "zero", allowing its use with
  1577 other numeric types and also as the identity of groups, rings, etc.;
  1578 
  1579 * HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.
  1580 Types nat and int belong to this axclass;
  1581 
  1582 * HOL: greatly improved simplification involving numerals of type nat, int, real:
  1583    (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k
  1584    i*j + k + j*#3*i     simplifies to  #4*(i*j) + k
  1585   two terms #m*u and #n*u are replaced by #(m+n)*u
  1586     (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)
  1587   and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y
  1588     or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);
  1589 
  1590 * HOL: meson_tac is available (previously in ex/meson.ML); it is a
  1591 powerful prover for predicate logic but knows nothing of clasets; see
  1592 ex/mesontest.ML and ex/mesontest2.ML for example applications;
  1593 
  1594 * HOL: new version of "case_tac" subsumes both boolean case split and
  1595 "exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer
  1596 exists, may define val exhaust_tac = case_tac for ad-hoc portability;
  1597 
  1598 * HOL: simplification no longer dives into case-expressions: only the
  1599 selector expression is simplified, but not the remaining arms; to
  1600 enable full simplification of case-expressions for datatype t, you may
  1601 remove t.weak_case_cong from the simpset, either globally (Delcongs
  1602 [thm"t.weak_case_cong"];) or locally (delcongs [...]).
  1603 
  1604 * HOL/recdef: the recursion equations generated by 'recdef' for
  1605 function 'f' are now called f.simps instead of f.rules; if all
  1606 termination conditions are proved automatically, these simplification
  1607 rules are added to the simpset, as in primrec; rules may be named
  1608 individually as well, resulting in a separate list of theorems for
  1609 each equation;
  1610 
  1611 * HOL/While is a new theory that provides a while-combinator. It
  1612 permits the definition of tail-recursive functions without the
  1613 provision of a termination measure. The latter is necessary once the
  1614 invariant proof rule for while is applied.
  1615 
  1616 * HOL: new (overloaded) notation for the set of elements below/above
  1617 some element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.
  1618 
  1619 * HOL: theorems impI, allI, ballI bound as "strip";
  1620 
  1621 * HOL: new tactic induct_thm_tac: thm -> string -> int -> tactic
  1622 induct_tac th "x1 ... xn" expects th to have a conclusion of the form
  1623 P v1 ... vn and abbreviates res_inst_tac [("v1","x1"),...,("vn","xn")] th;
  1624 
  1625 * HOL/Real: "rabs" replaced by overloaded "abs" function;
  1626 
  1627 * HOL: theory Sexp now in HOL/Induct examples (it used to be part of
  1628 main HOL, but was unused);
  1629 
  1630 * HOL: fewer consts declared as global (e.g. have to refer to
  1631 "Lfp.lfp" instead of "lfp" internally; affects ML packages only);
  1632 
  1633 * HOL: tuned AST representation of nested pairs, avoiding bogus output
  1634 in case of overlap with user translations (e.g. judgements over
  1635 tuples); (note that the underlying logical represenation is still
  1636 bogus);
  1637 
  1638 
  1639 *** ZF ***
  1640 
  1641 * ZF: simplification automatically cancels common terms in arithmetic
  1642 expressions over nat and int;
  1643 
  1644 * ZF: new treatment of nat to minimize type-checking: all operators
  1645 coerce their operands to a natural number using the function natify,
  1646 making the algebraic laws unconditional;
  1647 
  1648 * ZF: as above, for int: operators coerce their operands to an integer
  1649 using the function intify;
  1650 
  1651 * ZF: the integer library now contains many of the usual laws for the
  1652 orderings, including $<=, and monotonicity laws for $+ and $*;
  1653 
  1654 * ZF: new example ZF/ex/NatSum to demonstrate integer arithmetic
  1655 simplification;
  1656 
  1657 * FOL and ZF: AddIffs now available, giving theorems of the form P<->Q
  1658 to the simplifier and classical reasoner simultaneously;
  1659 
  1660 
  1661 *** General ***
  1662 
  1663 * Provers: blast_tac now handles actual object-logic rules as
  1664 assumptions; note that auto_tac uses blast_tac internally as well;
  1665 
  1666 * Provers: new functions rulify/rulify_no_asm: thm -> thm for turning
  1667 outer -->/All/Ball into ==>/!!; qed_spec_mp now uses rulify_no_asm;
  1668 
  1669 * Provers: delrules now handles destruct rules as well (no longer need
  1670 explicit make_elim);
  1671 
  1672 * Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.
  1673   [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1674 use instead the strong form,
  1675   [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W
  1676 in HOL, FOL and ZF the function cla_make_elim will create such rules
  1677 from destruct-rules;
  1678 
  1679 * Provers: Simplifier.easy_setup provides a fast path to basic
  1680 Simplifier setup for new object-logics;
  1681 
  1682 * Pure: AST translation rules no longer require constant head on LHS;
  1683 
  1684 * Pure: improved name spaces: ambiguous output is qualified; support
  1685 for hiding of names;
  1686 
  1687 * system: smart setup of canonical ML_HOME, ISABELLE_INTERFACE, and
  1688 XSYMBOL_HOME; no longer need to do manual configuration in most
  1689 situations;
  1690 
  1691 * system: compression of ML heaps images may now be controlled via -c
  1692 option of isabelle and isatool usedir (currently only observed by
  1693 Poly/ML);
  1694 
  1695 * system: isatool installfonts may handle X-Symbol fonts as well (very
  1696 useful for remote X11);
  1697 
  1698 * system: provide TAGS file for Isabelle sources;
  1699 
  1700 * ML: infix 'OF' is a version of 'MRS' with more appropriate argument
  1701 order;
  1702 
  1703 * ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global
  1704 timing flag supersedes proof_timing and Toplevel.trace;
  1705 
  1706 * ML: new combinators |>> and |>>> for incremental transformations
  1707 with secondary results (e.g. certain theory extensions):
  1708 
  1709 * ML: PureThy.add_defs gets additional argument to indicate potential
  1710 overloading (usually false);
  1711 
  1712 * ML: PureThy.add_thms/add_axioms/add_defs now return theorems as
  1713 results;
  1714 
  1715 
  1716 
  1717 New in Isabelle99 (October 1999)
  1718 --------------------------------
  1719 
  1720 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  1721 
  1722 * HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)
  1723 are no longer simplified.  (This allows the simplifier to unfold recursive
  1724 functional programs.)  To restore the old behaviour, declare
  1725 
  1726     Delcongs [if_weak_cong];
  1727 
  1728 * HOL: Removed the obsolete syntax "Compl A"; use -A for set
  1729 complement;
  1730 
  1731 * HOL: the predicate "inj" is now defined by translation to "inj_on";
  1732 
  1733 * HOL/datatype: mutual_induct_tac no longer exists --
  1734   use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]
  1735 
  1736 * HOL/typedef: fixed type inference for representing set; type
  1737 arguments now have to occur explicitly on the rhs as type constraints;
  1738 
  1739 * ZF: The con_defs part of an inductive definition may no longer refer
  1740 to constants declared in the same theory;
  1741 
  1742 * HOL, ZF: the function mk_cases, generated by the inductive
  1743 definition package, has lost an argument.  To simplify its result, it
  1744 uses the default simpset instead of a supplied list of theorems.
  1745 
  1746 * HOL/List: the constructors of type list are now Nil and Cons;
  1747 
  1748 * Simplifier: the type of the infix ML functions
  1749         setSSolver addSSolver setSolver addSolver
  1750 is now  simpset * solver -> simpset  where `solver' is a new abstract type
  1751 for packaging solvers. A solver is created via
  1752         mk_solver: string -> (thm list -> int -> tactic) -> solver
  1753 where the string argument is only a comment.
  1754 
  1755 
  1756 *** Proof tools ***
  1757 
  1758 * Provers/Arith/fast_lin_arith.ML contains a functor for creating a
  1759 decision procedure for linear arithmetic. Currently it is used for
  1760 types `nat', `int', and `real' in HOL (see below); it can, should and
  1761 will be instantiated for other types and logics as well.
  1762 
  1763 * The simplifier now accepts rewrite rules with flexible heads, eg
  1764      hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y
  1765   They are applied like any rule with a non-pattern lhs, i.e. by first-order
  1766   matching.
  1767 
  1768 
  1769 *** General ***
  1770 
  1771 * New Isabelle/Isar subsystem provides an alternative to traditional
  1772 tactical theorem proving; together with the ProofGeneral/isar user
  1773 interface it offers an interactive environment for developing human
  1774 readable proof documents (Isar == Intelligible semi-automated
  1775 reasoning); for further information see isatool doc isar-ref,
  1776 src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/
  1777 
  1778 * improved and simplified presentation of theories: better HTML markup
  1779 (including colors), graph views in several sizes; isatool usedir now
  1780 provides a proper interface for user theories (via -P option); actual
  1781 document preparation based on (PDF)LaTeX is available as well (for
  1782 new-style theories only); see isatool doc system for more information;
  1783 
  1784 * native support for Proof General, both for classic Isabelle and
  1785 Isabelle/Isar;
  1786 
  1787 * ML function thm_deps visualizes dependencies of theorems and lemmas,
  1788 using the graph browser tool;
  1789 
  1790 * Isabelle manuals now also available as PDF;
  1791 
  1792 * theory loader rewritten from scratch (may not be fully
  1793 bug-compatible); old loadpath variable has been replaced by show_path,
  1794 add_path, del_path, reset_path functions; new operations such as
  1795 update_thy, touch_thy, remove_thy, use/update_thy_only (see also
  1796 isatool doc ref);
  1797 
  1798 * improved isatool install: option -k creates KDE application icon,
  1799 option -p DIR installs standalone binaries;
  1800 
  1801 * added ML_PLATFORM setting (useful for cross-platform installations);
  1802 more robust handling of platform specific ML images for SML/NJ;
  1803 
  1804 * the settings environment is now statically scoped, i.e. it is never
  1805 created again in sub-processes invoked from isabelle, isatool, or
  1806 Isabelle;
  1807 
  1808 * path element specification '~~' refers to '$ISABELLE_HOME';
  1809 
  1810 * in locales, the "assumes" and "defines" parts may be omitted if
  1811 empty;
  1812 
  1813 * new print_mode "xsymbols" for extended symbol support (e.g. genuine
  1814 long arrows);
  1815 
  1816 * new print_mode "HTML";
  1817 
  1818 * new flag show_tags controls display of tags of theorems (which are
  1819 basically just comments that may be attached by some tools);
  1820 
  1821 * Isamode 2.6 requires patch to accomodate change of Isabelle font
  1822 mode and goal output format:
  1823 
  1824 diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el
  1825 244c244
  1826 <       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)
  1827 ---
  1828 >       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)
  1829 diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el
  1830 181c181
  1831 < (defconst proofstate-proofstart-regexp "^Level [0-9]+$"
  1832 ---
  1833 > (defconst proofstate-proofstart-regexp "^Level [0-9]+"
  1834 
  1835 * function bind_thms stores lists of theorems (cf. bind_thm);
  1836 
  1837 * new shorthand tactics ftac, eatac, datac, fatac;
  1838 
  1839 * qed (and friends) now accept "" as result name; in that case the
  1840 theorem is not stored, but proper checks and presentation of the
  1841 result still apply;
  1842 
  1843 * theorem database now also indexes constants "Trueprop", "all",
  1844 "==>", "=="; thus thms_containing, findI etc. may retrieve more rules;
  1845 
  1846 
  1847 *** HOL ***
  1848 
  1849 ** HOL arithmetic **
  1850 
  1851 * There are now decision procedures for linear arithmetic over nat and
  1852 int:
  1853 
  1854 1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',
  1855 `+', `-', `Suc', `min', `max' and numerical constants; other subterms
  1856 are treated as atomic; subformulae not involving type `nat' or `int'
  1857 are ignored; quantified subformulae are ignored unless they are
  1858 positive universal or negative existential. The tactic has to be
  1859 invoked by hand and can be a little bit slow. In particular, the
  1860 running time is exponential in the number of occurrences of `min' and
  1861 `max', and `-' on `nat'.
  1862 
  1863 2. fast_arith_tac is a cut-down version of arith_tac: it only takes
  1864 (negated) (in)equalities among the premises and the conclusion into
  1865 account (i.e. no compound formulae) and does not know about `min' and
  1866 `max', and `-' on `nat'. It is fast and is used automatically by the
  1867 simplifier.
  1868 
  1869 NB: At the moment, these decision procedures do not cope with mixed
  1870 nat/int formulae where the two parts interact, such as `m < n ==>
  1871 int(m) < int(n)'.
  1872 
  1873 * HOL/Numeral provides a generic theory of numerals (encoded
  1874 efficiently as bit strings); setup for types nat/int/real is in place;
  1875 INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than
  1876 int, existing theories and proof scripts may require a few additional
  1877 type constraints;
  1878 
  1879 * integer division and remainder can now be performed on constant
  1880 arguments;
  1881 
  1882 * many properties of integer multiplication, division and remainder
  1883 are now available;
  1884 
  1885 * An interface to the Stanford Validity Checker (SVC) is available through the
  1886 tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic
  1887 are proved automatically.  SVC must be installed separately, and its results
  1888 must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any
  1889 invocation of the underlying oracle).  For SVC see
  1890   http://verify.stanford.edu/SVC
  1891 
  1892 * IsaMakefile: the HOL-Real target now builds an actual image;
  1893 
  1894 
  1895 ** HOL misc **
  1896 
  1897 * HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces
  1898 (in Isabelle/Isar) -- by Gertrud Bauer;
  1899 
  1900 * HOL/BCV: generic model of bytecode verification, i.e. data-flow
  1901 analysis for assembly languages with subtypes;
  1902 
  1903 * HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization
  1904 -- avoids syntactic ambiguities and treats state, transition, and
  1905 temporal levels more uniformly; introduces INCOMPATIBILITIES due to
  1906 changed syntax and (many) tactics;
  1907 
  1908 * HOL/inductive: Now also handles more general introduction rules such
  1909   as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity
  1910   theorems are now maintained within the theory (maintained via the
  1911   "mono" attribute);
  1912 
  1913 * HOL/datatype: Now also handles arbitrarily branching datatypes
  1914   (using function types) such as
  1915 
  1916   datatype 'a tree = Atom 'a | Branch "nat => 'a tree"
  1917 
  1918 * HOL/record: record_simproc (part of the default simpset) takes care
  1919 of selectors applied to updated records; record_split_tac is no longer
  1920 part of the default claset; update_defs may now be removed from the
  1921 simpset in many cases; COMPATIBILITY: old behavior achieved by
  1922 
  1923   claset_ref () := claset() addSWrapper record_split_wrapper;
  1924   Delsimprocs [record_simproc]
  1925 
  1926 * HOL/typedef: fixed type inference for representing set; type
  1927 arguments now have to occur explicitly on the rhs as type constraints;
  1928 
  1929 * HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem
  1930 names rather than an ML expression;
  1931 
  1932 * HOL/defer_recdef (TFL): like recdef but the well-founded relation can be
  1933 supplied later.  Program schemes can be defined, such as
  1934     "While B C s = (if B s then While B C (C s) else s)"
  1935 where the well-founded relation can be chosen after B and C have been given.
  1936 
  1937 * HOL/List: the constructors of type list are now Nil and Cons;
  1938 INCOMPATIBILITY: while [] and infix # syntax is still there, of
  1939 course, ML tools referring to List.list.op # etc. have to be adapted;
  1940 
  1941 * HOL_quantifiers flag superseded by "HOL" print mode, which is
  1942 disabled by default; run isabelle with option -m HOL to get back to
  1943 the original Gordon/HOL-style output;
  1944 
  1945 * HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,
  1946 ALL x<=y. P, EX x<y. P, EX x<=y. P;
  1947 
  1948 * HOL basic syntax simplified (more orthogonal): all variants of
  1949 All/Ex now support plain / symbolic / HOL notation; plain syntax for
  1950 Eps operator is provided as well: "SOME x. P[x]";
  1951 
  1952 * HOL/Sum.thy: sum_case has been moved to HOL/Datatype;
  1953 
  1954 * HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made
  1955 thus available for user theories;
  1956 
  1957 * HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with
  1958 HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the
  1959 time;
  1960 
  1961 * HOL: new tactic smp_tac: int -> int -> tactic, which applies spec
  1962 several times and then mp;
  1963 
  1964 
  1965 *** LK ***
  1966 
  1967 * the notation <<...>> is now available as a notation for sequences of
  1968 formulas;
  1969 
  1970 * the simplifier is now installed
  1971 
  1972 * the axiom system has been generalized (thanks to Soren Heilmann)
  1973 
  1974 * the classical reasoner now has a default rule database
  1975 
  1976 
  1977 *** ZF ***
  1978 
  1979 * new primrec section allows primitive recursive functions to be given
  1980 directly (as in HOL) over datatypes and the natural numbers;
  1981 
  1982 * new tactics induct_tac and exhaust_tac for induction (or case
  1983 analysis) over datatypes and the natural numbers;
  1984 
  1985 * the datatype declaration of type T now defines the recursor T_rec;
  1986 
  1987 * simplification automatically does freeness reasoning for datatype
  1988 constructors;
  1989 
  1990 * automatic type-inference, with AddTCs command to insert new
  1991 type-checking rules;
  1992 
  1993 * datatype introduction rules are now added as Safe Introduction rules
  1994 to the claset;
  1995 
  1996 * the syntax "if P then x else y" is now available in addition to
  1997 if(P,x,y);
  1998 
  1999 
  2000 *** Internal programming interfaces ***
  2001 
  2002 * tuned simplifier trace output; new flag debug_simp;
  2003 
  2004 * structures Vartab / Termtab (instances of TableFun) offer efficient
  2005 tables indexed by indexname_ord / term_ord (compatible with aconv);
  2006 
  2007 * AxClass.axclass_tac lost the theory argument;
  2008 
  2009 * tuned current_goals_markers semantics: begin / end goal avoids
  2010 printing empty lines;
  2011 
  2012 * removed prs and prs_fn hook, which was broken because it did not
  2013 include \n in its semantics, forcing writeln to add one
  2014 uncoditionally; replaced prs_fn by writeln_fn; consider std_output:
  2015 string -> unit if you really want to output text without newline;
  2016 
  2017 * Symbol.output subject to print mode; INCOMPATIBILITY: defaults to
  2018 plain output, interface builders may have to enable 'isabelle_font'
  2019 mode to get Isabelle font glyphs as before;
  2020 
  2021 * refined token_translation interface; INCOMPATIBILITY: output length
  2022 now of type real instead of int;
  2023 
  2024 * theory loader actions may be traced via new ThyInfo.add_hook
  2025 interface (see src/Pure/Thy/thy_info.ML); example application: keep
  2026 your own database of information attached to *whole* theories -- as
  2027 opposed to intra-theory data slots offered via TheoryDataFun;
  2028 
  2029 * proper handling of dangling sort hypotheses (at last!);
  2030 Thm.strip_shyps and Drule.strip_shyps_warning take care of removing
  2031 extra sort hypotheses that can be witnessed from the type signature;
  2032 the force_strip_shyps flag is gone, any remaining shyps are simply
  2033 left in the theorem (with a warning issued by strip_shyps_warning);
  2034 
  2035 
  2036 
  2037 New in Isabelle98-1 (October 1998)
  2038 ----------------------------------
  2039 
  2040 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2041 
  2042 * several changes of automated proof tools;
  2043 
  2044 * HOL: major changes to the inductive and datatype packages, including
  2045 some minor incompatibilities of theory syntax;
  2046 
  2047 * HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now
  2048 called `inj_on';
  2049 
  2050 * HOL: removed duplicate thms in Arith:
  2051   less_imp_add_less  should be replaced by  trans_less_add1
  2052   le_imp_add_le      should be replaced by  trans_le_add1
  2053 
  2054 * HOL: unary minus is now overloaded (new type constraints may be
  2055 required);
  2056 
  2057 * HOL and ZF: unary minus for integers is now #- instead of #~.  In
  2058 ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is
  2059 now taken as an integer constant.
  2060 
  2061 * Pure: ML function 'theory_of' renamed to 'theory';
  2062 
  2063 
  2064 *** Proof tools ***
  2065 
  2066 * Simplifier:
  2067   1. Asm_full_simp_tac is now more aggressive.
  2068      1. It will sometimes reorient premises if that increases their power to
  2069         simplify.
  2070      2. It does no longer proceed strictly from left to right but may also
  2071         rotate premises to achieve further simplification.
  2072      For compatibility reasons there is now Asm_lr_simp_tac which is like the
  2073      old Asm_full_simp_tac in that it does not rotate premises.
  2074   2. The simplifier now knows a little bit about nat-arithmetic.
  2075 
  2076 * Classical reasoner: wrapper mechanism for the classical reasoner now
  2077 allows for selected deletion of wrappers, by introduction of names for
  2078 wrapper functionals.  This implies that addbefore, addSbefore,
  2079 addaltern, and addSaltern now take a pair (name, tactic) as argument,
  2080 and that adding two tactics with the same name overwrites the first
  2081 one (emitting a warning).
  2082   type wrapper = (int -> tactic) -> (int -> tactic)
  2083   setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by
  2084   addWrapper, addSWrapper: claset * (string * wrapper) -> claset
  2085   delWrapper, delSWrapper: claset *  string            -> claset
  2086   getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;
  2087 
  2088 * Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE
  2089 semantics; addbefore now affects only the unsafe part of step_tac
  2090 etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY
  2091 FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac
  2092 by Force_tac;
  2093 
  2094 * Classical reasoner: setwrapper to setWrapper and compwrapper to
  2095 compWrapper; added safe wrapper (and access functions for it);
  2096 
  2097 * HOL/split_all_tac is now much faster and fails if there is nothing
  2098 to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order
  2099 and the names of the automatically generated variables have changed.
  2100 split_all_tac has moved within claset() from unsafe wrappers to safe
  2101 wrappers, which means that !!-bound variables are split much more
  2102 aggressively, and safe_tac and clarify_tac now split such variables.
  2103 If this splitting is not appropriate, use delSWrapper "split_all_tac".
  2104 Note: the same holds for record_split_tac, which does the job of
  2105 split_all_tac for record fields.
  2106 
  2107 * HOL/Simplifier: Rewrite rules for case distinctions can now be added
  2108 permanently to the default simpset using Addsplits just like
  2109 Addsimps. They can be removed via Delsplits just like
  2110 Delsimps. Lower-case versions are also available.
  2111 
  2112 * HOL/Simplifier: The rule split_if is now part of the default
  2113 simpset. This means that the simplifier will eliminate all occurrences
  2114 of if-then-else in the conclusion of a goal. To prevent this, you can
  2115 either remove split_if completely from the default simpset by
  2116 `Delsplits [split_if]' or remove it in a specific call of the
  2117 simplifier using `... delsplits [split_if]'.  You can also add/delete
  2118 other case splitting rules to/from the default simpset: every datatype
  2119 generates suitable rules `split_t_case' and `split_t_case_asm' (where
  2120 t is the name of the datatype).
  2121 
  2122 * Classical reasoner / Simplifier combination: new force_tac (and
  2123 derivatives Force_tac, force) combines rewriting and classical
  2124 reasoning (and whatever other tools) similarly to auto_tac, but is
  2125 aimed to solve the given subgoal completely.
  2126 
  2127 
  2128 *** General ***
  2129 
  2130 * new top-level commands `Goal' and `Goalw' that improve upon `goal'
  2131 and `goalw': the theory is no longer needed as an explicit argument -
  2132 the current theory context is used; assumptions are no longer returned
  2133 at the ML-level unless one of them starts with ==> or !!; it is
  2134 recommended to convert to these new commands using isatool fixgoal
  2135 (backup your sources first!);
  2136 
  2137 * new top-level commands 'thm' and 'thms' for retrieving theorems from
  2138 the current theory context, and 'theory' to lookup stored theories;
  2139 
  2140 * new theory section 'locale' for declaring constants, assumptions and
  2141 definitions that have local scope;
  2142 
  2143 * new theory section 'nonterminals' for purely syntactic types;
  2144 
  2145 * new theory section 'setup' for generic ML setup functions
  2146 (e.g. package initialization);
  2147 
  2148 * the distribution now includes Isabelle icons: see
  2149 lib/logo/isabelle-{small,tiny}.xpm;
  2150 
  2151 * isatool install - install binaries with absolute references to
  2152 ISABELLE_HOME/bin;
  2153 
  2154 * isatool logo -- create instances of the Isabelle logo (as EPS);
  2155 
  2156 * print mode 'emacs' reserved for Isamode;
  2157 
  2158 * support multiple print (ast) translations per constant name;
  2159 
  2160 * theorems involving oracles are now printed with a suffixed [!];
  2161 
  2162 
  2163 *** HOL ***
  2164 
  2165 * there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');
  2166 
  2167 * HOL/inductive package reorganized and improved: now supports mutual
  2168 definitions such as
  2169 
  2170   inductive EVEN ODD
  2171     intrs
  2172       null "0 : EVEN"
  2173       oddI "n : EVEN ==> Suc n : ODD"
  2174       evenI "n : ODD ==> Suc n : EVEN"
  2175 
  2176 new theorem list "elims" contains an elimination rule for each of the
  2177 recursive sets; inductive definitions now handle disjunctive premises
  2178 correctly (also ZF);
  2179 
  2180 INCOMPATIBILITIES: requires Inductive as an ancestor; component
  2181 "mutual_induct" no longer exists - the induction rule is always
  2182 contained in "induct";
  2183 
  2184 
  2185 * HOL/datatype package re-implemented and greatly improved: now
  2186 supports mutually recursive datatypes such as
  2187 
  2188   datatype
  2189     'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)
  2190             | SUM ('a aexp) ('a aexp)
  2191             | DIFF ('a aexp) ('a aexp)
  2192             | NUM 'a
  2193   and
  2194     'a bexp = LESS ('a aexp) ('a aexp)
  2195             | AND ('a bexp) ('a bexp)
  2196             | OR ('a bexp) ('a bexp)
  2197 
  2198 as well as indirectly recursive datatypes such as
  2199 
  2200   datatype
  2201     ('a, 'b) term = Var 'a
  2202                   | App 'b ((('a, 'b) term) list)
  2203 
  2204 The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs
  2205 induction on mutually / indirectly recursive datatypes.
  2206 
  2207 Primrec equations are now stored in theory and can be accessed via
  2208 <function_name>.simps.
  2209 
  2210 INCOMPATIBILITIES:
  2211 
  2212   - Theories using datatypes must now have theory Datatype as an
  2213     ancestor.
  2214   - The specific <typename>.induct_tac no longer exists - use the
  2215     generic induct_tac instead.
  2216   - natE has been renamed to nat.exhaust - use exhaust_tac
  2217     instead of res_inst_tac ... natE. Note that the variable
  2218     names in nat.exhaust differ from the names in natE, this
  2219     may cause some "fragile" proofs to fail.
  2220   - The theorems split_<typename>_case and split_<typename>_case_asm
  2221     have been renamed to <typename>.split and <typename>.split_asm.
  2222   - Since default sorts of type variables are now handled correctly,
  2223     some datatype definitions may have to be annotated with explicit
  2224     sort constraints.
  2225   - Primrec definitions no longer require function name and type
  2226     of recursive argument.
  2227 
  2228 Consider using isatool fixdatatype to adapt your theories and proof
  2229 scripts to the new package (backup your sources first!).
  2230 
  2231 
  2232 * HOL/record package: considerably improved implementation; now
  2233 includes concrete syntax for record types, terms, updates; theorems
  2234 for surjective pairing and splitting !!-bound record variables; proof
  2235 support is as follows:
  2236 
  2237   1) standard conversions (selectors or updates applied to record
  2238 constructor terms) are part of the standard simpset;
  2239 
  2240   2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are
  2241 made part of standard simpset and claset via addIffs;
  2242 
  2243   3) a tactic for record field splitting (record_split_tac) is part of
  2244 the standard claset (addSWrapper);
  2245 
  2246 To get a better idea about these rules you may retrieve them via
  2247 something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is
  2248 the name of your record type.
  2249 
  2250 The split tactic 3) conceptually simplifies by the following rule:
  2251 
  2252   "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"
  2253 
  2254 Thus any record variable that is bound by meta-all will automatically
  2255 blow up into some record constructor term, consequently the
  2256 simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall
  2257 solve record problems automatically.
  2258 
  2259 
  2260 * reorganized the main HOL image: HOL/Integ and String loaded by
  2261 default; theory Main includes everything;
  2262 
  2263 * automatic simplification of integer sums and comparisons, using cancellation;
  2264 
  2265 * added option_map_eq_Some and not_Some_eq to the default simpset and claset;
  2266 
  2267 * added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;
  2268 
  2269 * many new identities for unions, intersections, set difference, etc.;
  2270 
  2271 * expand_if, expand_split, expand_sum_case and expand_nat_case are now
  2272 called split_if, split_split, split_sum_case and split_nat_case (to go
  2273 with add/delsplits);
  2274 
  2275 * HOL/Prod introduces simplification procedure unit_eq_proc rewriting
  2276 (?x::unit) = (); this is made part of the default simpset, which COULD
  2277 MAKE EXISTING PROOFS FAIL under rare circumstances (consider
  2278 'Delsimprocs [unit_eq_proc];' as last resort); also note that
  2279 unit_abs_eta_conv is added in order to counter the effect of
  2280 unit_eq_proc on (%u::unit. f u), replacing it by f rather than by
  2281 %u.f();
  2282 
  2283 * HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which
  2284 makes more sense);
  2285 
  2286 * HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2287   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2288   disjointness reasoning but breaking a few old proofs.
  2289 
  2290 * HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1
  2291 to 'converse' from 'inverse' (for compatibility with ZF and some
  2292 literature);
  2293 
  2294 * HOL/recdef can now declare non-recursive functions, with {} supplied as
  2295 the well-founded relation;
  2296 
  2297 * HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of
  2298     Compl A.  The "Compl" syntax remains available as input syntax for this
  2299     release ONLY.
  2300 
  2301 * HOL/Update: new theory of function updates:
  2302     f(a:=b) == %x. if x=a then b else f x
  2303 may also be iterated as in f(a:=b,c:=d,...);
  2304 
  2305 * HOL/Vimage: new theory for inverse image of a function, syntax f-``B;
  2306 
  2307 * HOL/List:
  2308   - new function list_update written xs[i:=v] that updates the i-th
  2309     list position. May also be iterated as in xs[i:=a,j:=b,...].
  2310   - new function `upt' written [i..j(] which generates the list
  2311     [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper
  2312     bound write [i..j], which is a shorthand for [i..j+1(].
  2313   - new lexicographic orderings and corresponding wellfoundedness theorems.
  2314 
  2315 * HOL/Arith:
  2316   - removed 'pred' (predecessor) function;
  2317   - generalized some theorems about n-1;
  2318   - many new laws about "div" and "mod";
  2319   - new laws about greatest common divisors (see theory ex/Primes);
  2320 
  2321 * HOL/Relation: renamed the relational operator r^-1 "converse"
  2322 instead of "inverse";
  2323 
  2324 * HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness
  2325   of the multiset ordering;
  2326 
  2327 * directory HOL/Real: a construction of the reals using Dedekind cuts
  2328   (not included by default);
  2329 
  2330 * directory HOL/UNITY: Chandy and Misra's UNITY formalism;
  2331 
  2332 * directory HOL/Hoare: a new version of Hoare logic which permits many-sorted
  2333   programs, i.e. different program variables may have different types.
  2334 
  2335 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2336   [previously, this check worked only if the rewrite rule was unconditional]
  2337   Now rew can involve either definitions or equalities (either == or =).
  2338 
  2339 
  2340 *** ZF ***
  2341 
  2342 * theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains
  2343   only the theorems proved on ZF.ML;
  2344 
  2345 * ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;
  2346   It and 'sym RS equals0D' are now in the default  claset, giving automatic
  2347   disjointness reasoning but breaking a few old proofs.
  2348 
  2349 * ZF/Update: new theory of function updates
  2350     with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)
  2351   may also be iterated as in f(a:=b,c:=d,...);
  2352 
  2353 * in  let x=t in u(x), neither t nor u(x) has to be an FOL term.
  2354 
  2355 * calling (stac rew i) now fails if "rew" has no effect on the goal
  2356   [previously, this check worked only if the rewrite rule was unconditional]
  2357   Now rew can involve either definitions or equalities (either == or =).
  2358 
  2359 * case_tac provided for compatibility with HOL
  2360     (like the old excluded_middle_tac, but with subgoals swapped)
  2361 
  2362 
  2363 *** Internal programming interfaces ***
  2364 
  2365 * Pure: several new basic modules made available for general use, see
  2366 also src/Pure/README;
  2367 
  2368 * improved the theory data mechanism to support encapsulation (data
  2369 kind name replaced by private Object.kind, acting as authorization
  2370 key); new type-safe user interface via functor TheoryDataFun; generic
  2371 print_data function becomes basically useless;
  2372 
  2373 * removed global_names compatibility flag -- all theory declarations
  2374 are qualified by default;
  2375 
  2376 * module Pure/Syntax now offers quote / antiquote translation
  2377 functions (useful for Hoare logic etc. with implicit dependencies);
  2378 see HOL/ex/Antiquote for an example use;
  2379 
  2380 * Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->
  2381 cterm -> thm;
  2382 
  2383 * new tactical CHANGED_GOAL for checking that a tactic modifies a
  2384 subgoal;
  2385 
  2386 * Display.print_goals function moved to Locale.print_goals;
  2387 
  2388 * standard print function for goals supports current_goals_markers
  2389 variable for marking begin of proof, end of proof, start of goal; the
  2390 default is ("", "", ""); setting current_goals_markers := ("<proof>",
  2391 "</proof>", "<goal>") causes SGML like tagged proof state printing,
  2392 for example;
  2393 
  2394 
  2395 
  2396 New in Isabelle98 (January 1998)
  2397 --------------------------------
  2398 
  2399 *** Overview of INCOMPATIBILITIES (see below for more details) ***
  2400 
  2401 * changed lexical syntax of terms / types: dots made part of long
  2402 identifiers, e.g. "%x.x" no longer possible, should be "%x. x";
  2403 
  2404 * simpset (and claset) reference variable replaced by functions
  2405 simpset / simpset_ref;
  2406 
  2407 * no longer supports theory aliases (via merge) and non-trivial
  2408 implicit merge of thms' signatures;
  2409 
  2410 * most internal names of constants changed due to qualified names;
  2411 
  2412 * changed Pure/Sequence interface (see Pure/seq.ML);
  2413 
  2414 
  2415 *** General Changes ***
  2416 
  2417 * hierachically structured name spaces (for consts, types, axms, thms
  2418 etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of
  2419 old input syntactically incorrect (e.g. "%x.x"); COMPATIBILITY:
  2420 isatool fixdots ensures space after dots (e.g. "%x. x"); set
  2421 long_names for fully qualified output names; NOTE: ML programs
  2422 (special tactics, packages etc.) referring to internal names may have
  2423 to be adapted to cope with fully qualified names; in case of severe
  2424 backward campatibility problems try setting 'global_names' at compile
  2425 time to have enrything declared within a flat name space; one may also
  2426 fine tune name declarations in theories via the 'global' and 'local'
  2427 section;
  2428 
  2429 * reimplemented the implicit simpset and claset using the new anytype
  2430 data filed in signatures; references simpset:simpset ref etc. are
  2431 replaced by functions simpset:unit->simpset and
  2432 simpset_ref:unit->simpset ref; COMPATIBILITY: use isatool fixclasimp
  2433 to patch your ML files accordingly;
  2434 
  2435 * HTML output now includes theory graph data for display with Java
  2436 applet or isatool browser; data generated automatically via isatool
  2437 usedir (see -i option, ISABELLE_USEDIR_OPTIONS);
  2438 
  2439 * defs may now be conditional; improved rewrite_goals_tac to handle
  2440 conditional equations;
  2441 
  2442 * defs now admits additional type arguments, using TYPE('a) syntax;
  2443 
  2444 * theory aliases via merge (e.g. M=A+B+C) no longer supported, always
  2445 creates a new theory node; implicit merge of thms' signatures is
  2446 restricted to 'trivial' ones; COMPATIBILITY: one may have to use
  2447 transfer:theory->thm->thm in (rare) cases;
  2448 
  2449 * improved handling of draft signatures / theories; draft thms (and
  2450 ctyps, cterms) are automatically promoted to real ones;
  2451 
  2452 * slightly changed interfaces for oracles: admit many per theory, named
  2453 (e.g. oracle foo = mlfun), additional name argument for invoke_oracle;
  2454 
  2455 * print_goals: optional output of const types (set show_consts and
  2456 show_types);
  2457 
  2458 * improved output of warnings (###) and errors (***);
  2459 
  2460 * subgoal_tac displays a warning if the new subgoal has type variables;
  2461 
  2462 * removed old README and Makefiles;
  2463 
  2464 * replaced print_goals_ref hook by print_current_goals_fn and result_error_fn;
  2465 
  2466 * removed obsolete init_pps and init_database;
  2467 
  2468 * deleted the obsolete tactical STATE, which was declared by
  2469     fun STATE tacfun st = tacfun st st;
  2470 
  2471 * cd and use now support path variables, e.g. $ISABELLE_HOME, or ~
  2472 (which abbreviates $HOME);
  2473 
  2474 * changed Pure/Sequence interface (see Pure/seq.ML); COMPATIBILITY:
  2475 use isatool fixseq to adapt your ML programs (this works for fully
  2476 qualified references to the Sequence structure only!);
  2477 
  2478 * use_thy no longer requires writable current directory; it always
  2479 reloads .ML *and* .thy file, if either one is out of date;
  2480 
  2481 
  2482 *** Classical Reasoner ***
  2483 
  2484 * Clarify_tac, clarify_tac, clarify_step_tac, Clarify_step_tac: new
  2485 tactics that use classical reasoning to simplify a subgoal without
  2486 splitting it into several subgoals;
  2487 
  2488 * Safe_tac: like safe_tac but uses the default claset;
  2489 
  2490 
  2491 *** Simplifier ***
  2492 
  2493 * added simplification meta rules:
  2494     (asm_)(full_)simplify: simpset -> thm -> thm;
  2495 
  2496 * simplifier.ML no longer part of Pure -- has to be loaded by object
  2497 logics (again);
  2498 
  2499 * added prems argument to simplification procedures;
  2500 
  2501 * HOL, FOL, ZF: added infix function `addsplits':
  2502   instead of `<simpset> setloop (split_tac <thms>)'
  2503   you can simply write `<simpset> addsplits <thms>'
  2504 
  2505 
  2506 *** Syntax ***
  2507 
  2508 * TYPE('a) syntax for type reflection terms;
  2509 
  2510 * no longer handles consts with name "" -- declare as 'syntax' instead;
  2511 
  2512 * pretty printer: changed order of mixfix annotation preference (again!);
  2513 
  2514 * Pure: fixed idt/idts vs. pttrn/pttrns syntactic categories;
  2515 
  2516 
  2517 *** HOL ***
  2518 
  2519 * HOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2520   with `addloop' of the simplifier to faciliate case splitting in premises.
  2521 
  2522 * HOL/TLA: Stephan Merz's formalization of Lamport's Temporal Logic of Actions;
  2523 
  2524 * HOL/Auth: new protocol proofs including some for the Internet
  2525   protocol TLS;
  2526 
  2527 * HOL/Map: new theory of `maps' a la VDM;
  2528 
  2529 * HOL/simplifier: simplification procedures nat_cancel_sums for
  2530 cancelling out common nat summands from =, <, <= (in)equalities, or
  2531 differences; simplification procedures nat_cancel_factor for
  2532 cancelling common factor from =, <, <= (in)equalities over natural
  2533 sums; nat_cancel contains both kinds of procedures, it is installed by
  2534 default in Arith.thy -- this COULD MAKE EXISTING PROOFS FAIL;
  2535 
  2536 * HOL/simplifier: terms of the form
  2537   `? x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x)'  (or t=x)
  2538   are rewritten to
  2539   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t)',
  2540   and those of the form
  2541   `! x. P1(x) & ... & Pn(x) & x=t & Q1(x) & ... Qn(x) --> R(x)'  (or t=x)
  2542   are rewritten to
  2543   `P1(t) & ... & Pn(t) & Q1(t) & ... Qn(t) --> R(t)',
  2544 
  2545 * HOL/datatype
  2546   Each datatype `t' now comes with a theorem `split_t_case' of the form
  2547 
  2548   P(t_case f1 ... fn x) =
  2549      ( (!y1 ... ym1. x = C1 y1 ... ym1 --> P(f1 y1 ... ym1)) &
  2550         ...
  2551        (!y1 ... ymn. x = Cn y1 ... ymn --> P(f1 y1 ... ymn))
  2552      )
  2553 
  2554   and a theorem `split_t_case_asm' of the form
  2555 
  2556   P(t_case f1 ... fn x) =
  2557     ~( (? y1 ... ym1. x = C1 y1 ... ym1 & ~P(f1 y1 ... ym1)) |
  2558         ...
  2559        (? y1 ... ymn. x = Cn y1 ... ymn & ~P(f1 y1 ... ymn))
  2560      )
  2561   which can be added to a simpset via `addsplits'. The existing theorems
  2562   expand_list_case and expand_option_case have been renamed to
  2563   split_list_case and split_option_case.
  2564 
  2565 * HOL/Arithmetic:
  2566   - `pred n' is automatically converted to `n-1'.
  2567     Users are strongly encouraged not to use `pred' any longer,
  2568     because it will disappear altogether at some point.
  2569   - Users are strongly encouraged to write "0 < n" rather than
  2570     "n ~= 0". Theorems and proof tools have been modified towards this
  2571     `standard'.
  2572 
  2573 * HOL/Lists:
  2574   the function "set_of_list" has been renamed "set" (and its theorems too);
  2575   the function "nth" now takes its arguments in the reverse order and
  2576   has acquired the infix notation "!" as in "xs!n".
  2577 
  2578 * HOL/Set: UNIV is now a constant and is no longer translated to Compl{};
  2579 
  2580 * HOL/Set: The operator (UN x.B x) now abbreviates (UN x:UNIV. B x) and its
  2581   specialist theorems (like UN1_I) are gone.  Similarly for (INT x.B x);
  2582 
  2583 * HOL/record: extensible records with schematic structural subtyping
  2584 (single inheritance); EXPERIMENTAL version demonstrating the encoding,
  2585 still lacks various theorems and concrete record syntax;
  2586 
  2587 
  2588 *** HOLCF ***
  2589 
  2590 * removed "axioms" and "generated by" sections;
  2591 
  2592 * replaced "ops" section by extended "consts" section, which is capable of
  2593   handling the continuous function space "->" directly;
  2594 
  2595 * domain package:
  2596   . proves theorems immediately and stores them in the theory,
  2597   . creates hierachical name space,
  2598   . now uses normal mixfix annotations (instead of cinfix...),
  2599   . minor changes to some names and values (for consistency),
  2600   . e.g. cases -> casedist, dists_eq -> dist_eqs, [take_lemma] -> take_lemmas,
  2601   . separator between mutual domain defs: changed "," to "and",
  2602   . improved handling of sort constraints;  now they have to
  2603     appear on the left-hand side of the equations only;
  2604 
  2605 * fixed LAM <x,y,zs>.b syntax;
  2606 
  2607 * added extended adm_tac to simplifier in HOLCF -- can now discharge
  2608 adm (%x. P (t x)), where P is chainfinite and t continuous;
  2609 
  2610 
  2611 *** FOL and ZF ***
  2612 
  2613 * FOL: there is a new splitter `split_asm_tac' that can be used e.g.
  2614   with `addloop' of the simplifier to faciliate case splitting in premises.
  2615 
  2616 * qed_spec_mp, qed_goal_spec_mp, qed_goalw_spec_mp are available, as
  2617 in HOL, they strip ALL and --> from proved theorems;
  2618 
  2619 
  2620 
  2621 New in Isabelle94-8 (May 1997)
  2622 ------------------------------
  2623 
  2624 *** General Changes ***
  2625 
  2626 * new utilities to build / run / maintain Isabelle etc. (in parts
  2627 still somewhat experimental); old Makefiles etc. still functional;
  2628 
  2629 * new 'Isabelle System Manual';
  2630 
  2631 * INSTALL text, together with ./configure and ./build scripts;
  2632 
  2633 * reimplemented type inference for greater efficiency, better error
  2634 messages and clean internal interface;
  2635 
  2636 * prlim command for dealing with lots of subgoals (an easier way of
  2637 setting goals_limit);
  2638 
  2639 
  2640 *** Syntax ***
  2641 
  2642 * supports alternative (named) syntax tables (parser and pretty
  2643 printer); internal interface is provided by add_modesyntax(_i);
  2644 
  2645 * Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
  2646 be used in conjunction with the Isabelle symbol font; uses the
  2647 "symbols" syntax table;
  2648 
  2649 * added token_translation interface (may translate name tokens in
  2650 arbitrary ways, dependent on their type (free, bound, tfree, ...) and
  2651 the current print_mode); IMPORTANT: user print translation functions
  2652 are responsible for marking newly introduced bounds
  2653 (Syntax.mark_boundT);
  2654 
  2655 * token translations for modes "xterm" and "xterm_color" that display
  2656 names in bold, underline etc. or colors (which requires a color
  2657 version of xterm);
  2658 
  2659 * infixes may now be declared with names independent of their syntax;
  2660 
  2661 * added typed_print_translation (like print_translation, but may
  2662 access type of constant);
  2663 
  2664 
  2665 *** Classical Reasoner ***
  2666 
  2667 Blast_tac: a new tactic!  It is often more powerful than fast_tac, but has
  2668 some limitations.  Blast_tac...
  2669   + ignores addss, addbefore, addafter; this restriction is intrinsic
  2670   + ignores elimination rules that don't have the correct format
  2671         (the conclusion MUST be a formula variable)
  2672   + ignores types, which can make HOL proofs fail
  2673   + rules must not require higher-order unification, e.g. apply_type in ZF
  2674     [message "Function Var's argument not a bound variable" relates to this]
  2675   + its proof strategy is more general but can actually be slower
  2676 
  2677 * substitution with equality assumptions no longer permutes other
  2678 assumptions;
  2679 
  2680 * minor changes in semantics of addafter (now called addaltern); renamed
  2681 setwrapper to setWrapper and compwrapper to compWrapper; added safe wrapper
  2682 (and access functions for it);
  2683 
  2684 * improved combination of classical reasoner and simplifier:
  2685   + functions for handling clasimpsets
  2686   + improvement of addss: now the simplifier is called _after_ the
  2687     safe steps.
  2688   + safe variant of addss called addSss: uses safe simplifications
  2689     _during_ the safe steps. It is more complete as it allows multiple
  2690     instantiations of unknowns (e.g. with slow_tac).
  2691 
  2692 *** Simplifier ***
  2693 
  2694 * added interface for simplification procedures (functions that
  2695 produce *proven* rewrite rules on the fly, depending on current
  2696 redex);
  2697 
  2698 * ordering on terms as parameter (used for ordered rewriting);
  2699 
  2700 * new functions delcongs, deleqcongs, and Delcongs. richer rep_ss;
  2701 
  2702 * the solver is now split into a safe and an unsafe part.
  2703 This should be invisible for the normal user, except that the
  2704 functions setsolver and addsolver have been renamed to setSolver and
  2705 addSolver; added safe_asm_full_simp_tac;
  2706 
  2707 
  2708 *** HOL ***
  2709 
  2710 * a generic induction tactic `induct_tac' which works for all datatypes and
  2711 also for type `nat';
  2712 
  2713 * a generic case distinction tactic `exhaust_tac' which works for all
  2714 datatypes and also for type `nat';
  2715 
  2716 * each datatype comes with a function `size';
  2717 
  2718 * patterns in case expressions allow tuple patterns as arguments to
  2719 constructors, for example `case x of [] => ... | (x,y,z)#ps => ...';
  2720 
  2721 * primrec now also works with type nat;
  2722 
  2723 * recdef: a new declaration form, allows general recursive functions to be
  2724 defined in theory files.  See HOL/ex/Fib, HOL/ex/Primes, HOL/Subst/Unify.
  2725 
  2726 * the constant for negation has been renamed from "not" to "Not" to
  2727 harmonize with FOL, ZF, LK, etc.;
  2728 
  2729 * HOL/ex/LFilter theory of a corecursive "filter" functional for
  2730 infinite lists;
  2731 
  2732 * HOL/Modelcheck demonstrates invocation of model checker oracle;
  2733 
  2734 * HOL/ex/Ring.thy declares cring_simp, which solves equational
  2735 problems in commutative rings, using axiomatic type classes for + and *;
  2736 
  2737 * more examples in HOL/MiniML and HOL/Auth;
  2738 
  2739 * more default rewrite rules for quantifiers, union/intersection;
  2740 
  2741 * a new constant `arbitrary == @x.False';
  2742 
  2743 * HOLCF/IOA replaces old HOL/IOA;
  2744 
  2745 * HOLCF changes: derived all rules and arities
  2746   + axiomatic type classes instead of classes
  2747   + typedef instead of faking type definitions
  2748   + eliminated the internal constants less_fun, less_cfun, UU_fun, UU_cfun etc.
  2749   + new axclasses cpo, chfin, flat with flat < chfin < pcpo < cpo < po
  2750   + eliminated the types void, one, tr
  2751   + use unit lift and bool lift (with translations) instead of one and tr
  2752   + eliminated blift from Lift3.thy (use Def instead of blift)
  2753   all eliminated rules are derived as theorems --> no visible changes ;
  2754 
  2755 
  2756 *** ZF ***
  2757 
  2758 * ZF now has Fast_tac, Simp_tac and Auto_tac.  Union_iff is a now a default
  2759 rewrite rule; this may affect some proofs.  eq_cs is gone but can be put back
  2760 as ZF_cs addSIs [equalityI];
  2761 
  2762 
  2763 
  2764 New in Isabelle94-7 (November 96)
  2765 ---------------------------------
  2766 
  2767 * allowing negative levels (as offsets) in prlev and choplev;
  2768 
  2769 * super-linear speedup for large simplifications;
  2770 
  2771 * FOL, ZF and HOL now use miniscoping: rewriting pushes
  2772 quantifications in as far as possible (COULD MAKE EXISTING PROOFS
  2773 FAIL); can suppress it using the command Delsimps (ex_simps @
  2774 all_simps); De Morgan laws are also now included, by default;
  2775 
  2776 * improved printing of ==>  :  ~:
  2777 
  2778 * new object-logic "Sequents" adds linear logic, while replacing LK
  2779 and Modal (thanks to Sara Kalvala);
  2780 
  2781 * HOL/Auth: correctness proofs for authentication protocols;
  2782 
  2783 * HOL: new auto_tac combines rewriting and classical reasoning (many
  2784 examples on HOL/Auth);
  2785 
  2786 * HOL: new command AddIffs for declaring theorems of the form P=Q to
  2787 the rewriter and classical reasoner simultaneously;
  2788 
  2789 * function uresult no longer returns theorems in "standard" format;
  2790 regain previous version by: val uresult = standard o uresult;
  2791 
  2792 
  2793 
  2794 New in Isabelle94-6
  2795 -------------------
  2796 
  2797 * oracles -- these establish an interface between Isabelle and trusted
  2798 external reasoners, which may deliver results as theorems;
  2799 
  2800 * proof objects (in particular record all uses of oracles);
  2801 
  2802 * Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;
  2803 
  2804 * "constdefs" section in theory files;
  2805 
  2806 * "primrec" section (HOL) no longer requires names;
  2807 
  2808 * internal type "tactic" now simply "thm -> thm Sequence.seq";
  2809 
  2810 
  2811 
  2812 New in Isabelle94-5
  2813 -------------------
  2814 
  2815 * reduced space requirements;
  2816 
  2817 * automatic HTML generation from theories;
  2818 
  2819 * theory files no longer require "..." (quotes) around most types;
  2820 
  2821 * new examples, including two proofs of the Church-Rosser theorem;
  2822 
  2823 * non-curried (1994) version of HOL is no longer distributed;
  2824 
  2825 
  2826 
  2827 New in Isabelle94-4
  2828 -------------------
  2829 
  2830 * greatly reduced space requirements;
  2831 
  2832 * theory files (.thy) no longer require \...\ escapes at line breaks;
  2833 
  2834 * searchable theorem database (see the section "Retrieving theorems" on
  2835 page 8 of the Reference Manual);
  2836 
  2837 * new examples, including Grabczewski's monumental case study of the
  2838 Axiom of Choice;
  2839 
  2840 * The previous version of HOL renamed to Old_HOL;
  2841 
  2842 * The new version of HOL (previously called CHOL) uses a curried syntax
  2843 for functions.  Application looks like f a b instead of f(a,b);
  2844 
  2845 * Mutually recursive inductive definitions finally work in HOL;
  2846 
  2847 * In ZF, pattern-matching on tuples is now available in all abstractions and
  2848 translates to the operator "split";
  2849 
  2850 
  2851 
  2852 New in Isabelle94-3
  2853 -------------------
  2854 
  2855 * new infix operator, addss, allowing the classical reasoner to
  2856 perform simplification at each step of its search.  Example:
  2857         fast_tac (cs addss ss)
  2858 
  2859 * a new logic, CHOL, the same as HOL, but with a curried syntax
  2860 for functions.  Application looks like f a b instead of f(a,b).  Also pairs
  2861 look like (a,b) instead of <a,b>;
  2862 
  2863 * PLEASE NOTE: CHOL will eventually replace HOL!
  2864 
  2865 * In CHOL, pattern-matching on tuples is now available in all abstractions.
  2866 It translates to the operator "split".  A new theory of integers is available;
  2867 
  2868 * In ZF, integer numerals now denote two's-complement binary integers.
  2869 Arithmetic operations can be performed by rewriting.  See ZF/ex/Bin.ML;
  2870 
  2871 * Many new examples: I/O automata, Church-Rosser theorem, equivalents
  2872 of the Axiom of Choice;
  2873 
  2874 
  2875 
  2876 New in Isabelle94-2
  2877 -------------------
  2878 
  2879 * Significantly faster resolution;
  2880 
  2881 * the different sections in a .thy file can now be mixed and repeated
  2882 freely;
  2883 
  2884 * Database of theorems for FOL, HOL and ZF.  New
  2885 commands including qed, qed_goal and bind_thm store theorems in the database.
  2886 
  2887 * Simple database queries: return a named theorem (get_thm) or all theorems of
  2888 a given theory (thms_of), or find out what theory a theorem was proved in
  2889 (theory_of_thm);
  2890 
  2891 * Bugs fixed in the inductive definition and datatype packages;
  2892 
  2893 * The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
  2894 and HOL_dup_cs obsolete;
  2895 
  2896 * Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
  2897 have been removed;
  2898 
  2899 * Simpler definition of function space in ZF;
  2900 
  2901 * new results about cardinal and ordinal arithmetic in ZF;
  2902 
  2903 * 'subtype' facility in HOL for introducing new types as subsets of existing
  2904 types;
  2905 
  2906 
  2907 $Id$