Isabelle NEWS -- history user-relevant changes

 ==============================================

 New in this Isabelle version

 ----------------------------

 *** General ***

 * Simplified main Isabelle executables, with less surprises on

 case-insensitive file-systems (such as Mac OS).

   - The main Isabelle tool wrapper is now called "isabelle" instead of

     "isatool."

   - The former "isabelle" alias for "isabelle-process" has been

     removed (should rarely occur to regular users).

   - The former "isabelle-interface" and its alias "Isabelle" have been

     removed (interfaces are now regular Isabelle tools).

 Within scripts and make files, the Isabelle environment variables

 ISABELLE_TOOL and ISABELLE_PROCESS replace old ISATOOL and ISABELLE,

 respectively.  (The latter are still available as legacy feature.)

 The old isabelle-interface wrapper could react in confusing ways if

 the interface was uninstalled or changed otherwise.  Individual

 interface tool configuration is now more explicit, see also the

 Isabelle system manual.  In particular, Proof General is now available

 via "isabelle emacs".

 INCOMPATIBILITY, need to adapt derivative scripts.  Users may need to

 purge installed copies of Isabelle executables and re-run "isabelle

 install -p ...", or use symlinks.

 * The default for ISABELLE_HOME_USER is now ~/.isabelle instead of the

 old ~/isabelle, which was slightly non-standard and apt cause

 surprises on case-insensitive file-systems.

 INCOMPATIBILITY, need to move existing ~/isabelle/etc,

 ~/isabelle/heaps, ~/isabelle/browser_info to the new place.  Special

 care is required when using older releases of Isabelle.  Note that

 ISABELLE_HOME_USER can be changed in Isabelle/etc/settings of any

 Isabelle distribution.

 * The Isabelle System Manual (system) has been updated, with formally

 checked references as hyperlinks.

 * Generalized Isar history, with support for linear undo, direct state

 addressing etc.

 * Recovered hiding of consts, which was accidentally broken in

 Isabelle2007.  Potential INCOMPATIBILITY, ``hide const c'' really

 makes c inaccessible; consider using ``hide (open) const c'' instead.

 * Removed exotic 'token_translation' command.  INCOMPATIBILITY, use ML

 interface instead.

 *** Pure ***

 * Slightly more coherent Pure syntax, with updated documentation in

 isar-ref manual.  Removed locales meta_term_syntax and

 meta_conjunction_syntax: TERM and &&& (formerly &&) are now permanent,

 INCOMPATIBILITY in rare situations.

 * Goal-directed proof now enforces strict proof irrelevance wrt. sort

 hypotheses.  Sorts required in the course of reasoning need to be

 covered by the constraints in the initial statement, completed by the

 type instance information of the background theory.  Non-trivial sort

 hypotheses, which rarely occur in practice, may be specified via

 vacuous propositions of the form SORT_CONSTRAINT('a::c).  For example:

   lemma assumes "SORT_CONSTRAINT('a::empty)" shows False ...

 The result contains an implicit sort hypotheses as before --

 SORT_CONSTRAINT premises are eliminated as part of the canonical rule

 normalization.

 * Changed defaults for unify configuration options:

   unify_trace_bound = 50 (formerly 25)

   unify_search_bound = 60 (formerly 30)

 * Different bookkeeping for code equations:

   a) On theory merge, the last set of code equations for a particular constant

      is taken (in accordance with the policy applied by other parts of the

      code generator framework).

   b) Code equations stemming from explicit declarations (e.g. code attribute)

      gain priority over default code equations stemming from definition, primrec,

      fun etc.

   INCOMPATIBILITY.

 * Global versions of theorems stemming from classes do not carry

 a parameter prefix any longer.  INCOMPATIBILITY.

 * Dropped locale element "includes".  This is a major INCOMPATIBILITY.

 In existing theorem specifications replace the includes element by the

 respective context elements of the included locale, omitting those that

 are already present in the theorem specification.  Multiple assume

 elements of a locale should be replaced by a single one involving the

 locale predicate.  In the proof body, declarations (most notably

 theorems) may be regained by interpreting the respective locales in the

 proof context as required (command "interpret").

 If using "includes" in replacement of a target solely because the

 parameter types in the theorem are not as general as in the target,

 consider declaring a new locale with additional type constraints on the

 parameters (context element "constrains").

 * Dropped "locale (open)".  INCOMPATBILITY.

 * Interpretation commands no longer attempt to simplify goal.

 INCOMPATIBILITY: in rare situations the generated goal differs.  Use

 methods intro_locales and unfold_locales to clarify.

 * Interpretation commands no longer accept interpretation attributes.

 INCOMPATBILITY.

 * Command 'instance': attached definitions no longer accepted.

 INCOMPATIBILITY, use proper 'instantiation' target.

 * Keyword 'code_exception' now named 'code_abort'.  INCOMPATIBILITY.

 * The 'axiomatization' command now only works within a global theory

 context.  INCOMPATIBILITY.

 *** Document preparation ***

 * Antiquotation @{lemma} now imitates a regular terminal proof,

 demanding keyword 'by' and supporting the full method expression

 syntax just like the Isar command 'by'.

 *** HOL ***

 * If methods "eval" and "evaluation" encounter a structured proof state

 with !!/==>, only the conclusion is evaluated to True (if possible),

 avoiding strange error messages.

 * Simplifier: simproc for let expressions now unfolds if bound variable

 occurs at most one time in let expression body.  INCOMPATIBILITY.

 * New classes "top" and "bot" with corresponding operations "top" and "bot"

 in theory Orderings;  instantiation of class "complete_lattice" requires

 instantiation of classes "top" and "bot".  INCOMPATIBILITY.

 * Changed definition lemma "less_fun_def" in order to provide an instance

 for preorders on functions;  use lemma "less_le" instead.  INCOMPATIBILITY.

 * Unified theorem tables for both code code generators.  Thus

 [code func] has disappeared and only [code] remains.  INCOMPATIBILITY.

 * Constants "undefined" and "default" replace "arbitrary".  Usually

 "undefined" is the right choice to replace "arbitrary", though logically

 there is no difference.  INCOMPATIBILITY.

 * Generic ATP manager for Sledgehammer, based on ML threads instead of

 Posix processes.  Avoids potentially expensive forking of the ML

 process.  New thread-based implementation also works on non-Unix

 platforms (Cygwin).  Provers are no longer hardwired, but defined

 within the theory via plain ML wrapper functions.  Basic Sledgehammer

 commands are covered in the isar-ref manual

 * Wrapper scripts for remote SystemOnTPTP service allows to use

 sledgehammer without local ATP installation (Vampire etc.).  See also

 ISABELLE_HOME/contrib/SystemOnTPTP and the VAMPIRE_HOME setting

 variable.  Other provers may be included via suitable ML wrappers, see

 also src/HOL/ATP_Linkup.thy.

 * Normalization by evaluation now allows non-leftlinear equations.

 Declare with attribute [code nbe].

 * Command "value" now integrates different evaluation

 mechanisms.  The result of the first successful evaluation mechanism

 is printed.  In square brackets a particular named evaluation

 mechanisms may be specified (currently, [SML], [code] or [nbe]).  See

 further src/HOL/ex/Eval_Examples.thy.

 * HOL/Orderings: class "wellorder" moved here, with explicit induction

 rule "less_induct" as assumption.  For instantiation of "wellorder" by

 means of predicate "wf", use rule wf_wellorderI.  INCOMPATIBILITY.

 * HOL/Orderings: added class "preorder" as superclass of "order".

 INCOMPATIBILITY: Instantiation proofs for order, linorder

 etc. slightly changed.  Some theorems named order_class.* now named

 preorder_class.*.

 * HOL/Finite_Set: added a new fold combinator of type

   ('a => 'b => 'b) => 'b => 'a set => 'b

 Occasionally this is more convenient than the old fold combinator which is

 now defined in terms of the new one and renamed to fold_image.

 * HOL/Ring_and_Field and HOL/Divides: Definition of "op dvd" has been

 moved to separate class dvd in Ring_and_Field; a couple of lemmas on

 dvd has been generalized to class comm_semiring_1.  Likewise a bunch

 of lemmas from Divides has been generalized from nat to class

 semiring_div.  INCOMPATIBILITY.  This involves the following theorem

 renames resulting from duplicate elimination:

     dvd_def_mod ~>          dvd_eq_mod_eq_0

     zero_dvd_iff ~>         dvd_0_left_iff

     dvd_0 ~>                dvd_0_right

     DIVISION_BY_ZERO_DIV ~> div_by_0

     DIVISION_BY_ZERO_MOD ~> mod_by_0

     mult_div ~>             div_mult_self2_is_id

     mult_mod ~>             mod_mult_self2_is_0

 * HOL/Library/GCD: Curried operations gcd, lcm (for nat) and zgcd,

 zlcm (for int); carried together from various gcd/lcm developements in

 the HOL Distribution.  zgcd and zlcm replace former igcd and ilcm;

 corresponding theorems renamed accordingly.  INCOMPATIBILY.  To

 recover tupled syntax, use syntax declarations like:

     hide (open) const gcd

     abbreviation gcd where

       "gcd == (%(a, b). GCD.gcd a b)"

     notation (output)

       GCD.gcd ("gcd '(_, _')")

 (analogously for lcm, zgcd, zlcm).

 * HOL/Real/Rational: 'Fract k 0' now equals '0'.  INCOMPATIBILITY.

 * New ML antiquotation @{code}: takes constant as argument, generates

 corresponding code in background and inserts name of the corresponding

 resulting ML value/function/datatype constructor binding in place.

 All occurrences of @{code} with a single ML block are generated

 simultaneously.  Provides a generic and safe interface for

 instrumentalizing code generation.  See HOL/ex/Code_Antiq for a toy

 example, or HOL/Complex/ex/ReflectedFerrack for a more ambitious

 application.  In future you ought refrain from ad-hoc compiling

 generated SML code on the ML toplevel.  Note that (for technical

 reasons) @{code} cannot refer to constants for which user-defined

 serializations are set.  Refer to the corresponding ML counterpart

 directly in that cases.

 * Integrated image HOL-Complex with HOL.  Entry points Main.thy and

 Complex_Main.thy remain as they are.

 * New image HOL-Plain provides a minimal HOL with the most important

 tools available (inductive, datatype, primrec, ...).  By convention

 the corresponding theory Plain should be ancestor of every further

 (library) theory.  Some library theories now have ancestor Plain

 (instead of Main), thus theory Main occasionally has to be imported

 explicitly.

 * The metis method now fails in the usual manner, rather than raising

 an exception, if it determines that it cannot prove the theorem.

 * The metis method no longer fails because the theorem is too trivial

 (contains the empty clause).

 * Methods "case_tac" and "induct_tac" now refer to the very same rules

 as the structured Isar versions "cases" and "induct", cf. the

 corresponding "cases" and "induct" attributes.  Mutual induction rules

 are now presented as a list of individual projections

 (e.g. foo_bar.inducts for types foo and bar); the old format with

 explicit HOL conjunction is no longer supported.  INCOMPATIBILITY, in

 rare situations a different rule is selected --- notably nested tuple

 elimination instead of former prod.exhaust: use explicit (case_tac t

 rule: prod.exhaust) here.

 * Attributes "cases", "induct", "coinduct" support "del" option.

 * Removed fact "case_split_thm", which duplicates "case_split".

 * Command 'rep_datatype': instead of theorem names the command now

 takes a list of terms denoting the constructors of the type to be

 represented as datatype.  The characteristic theorems have to be

 proven.  INCOMPATIBILITY.  Also observe that the following theorems

 have disappeared in favour of existing ones:

     unit_induct                 ~> unit.induct

     prod_induct                 ~> prod.induct

     sum_induct                  ~> sum.induct

     Suc_Suc_eq                  ~> nat.inject

     Suc_not_Zero Zero_not_Suc   ~> nat.distinct

 * Library/Nat_Infinity: added addition, numeral syntax and more

 instantiations for algebraic structures.  Removed some duplicate

 theorems.  Changes in simp rules.  INCOMPATIBILITY.

 * ATP selection (E/Vampire/Spass) is now via Proof General's settings

 menu.

 *** HOL-Algebra ***

 * New locales for orders and lattices where the equivalence relation

   is not restricted to equality.  INCOMPATIBILITY: all order and

   lattice locales use a record structure with field eq for the

   equivalence.

 * New theory of factorial domains.

 * Units_l_inv and Units_r_inv are now simprules by default.

 INCOMPATIBILITY.  Simplifier proof that require deletion of l_inv

 and/or r_inv will now also require deletion of these lemmas.

 * Renamed the following theorems.  INCOMPATIBILITY.

 UpperD ~> Upper_memD

 LowerD ~> Lower_memD

 least_carrier ~> least_closed

 greatest_carrier ~> greatest_closed

 greatest_Lower_above ~> greatest_Lower_below

 one_zero ~> carrier_one_zero

 one_not_zero ~> carrier_one_not_zero  (collision with assumption)

 *** HOL-NSA ***

 * Created new image HOL-NSA, containing theories of nonstandard

 analysis which were previously part of HOL-Complex.  Entry point

 Hyperreal.thy remains valid, but theories formerly using

 Complex_Main.thy should now use new entry point Hypercomplex.thy.

 *** ZF ***

 * Proof of Zorn's Lemma for partial orders.

 *** ML ***

 * Simplified ML oracle interface Thm.add_oracle promotes 'a -> cterm

 to 'a -> thm, while results are always tagged with an authentic oracle

 name.  The Isar command 'oracle' is now polymorphic, no argument type

 is specified.  INCOMPATIBILITY, need to simplify existing oracle code

 accordingly.  Note that extra performance may be gained by producing

 the cterm carefully, avoiding slow Thm.cterm_of.

 * ML bindings produced via Isar commands are stored within the Isar

 context (theory or proof).  Consequently, commands like 'use' and 'ML'

 become thread-safe and work with undo as expected (concerning

 top-level bindings, not side-effects on global references).

 INCOMPATIBILITY, need to provide proper Isar context when invoking the

 compiler at runtime; really global bindings need to be given outside a

 theory. [Poly/ML 5.2 or later]

 * Command 'ML_prf' is analogous to 'ML' but works within a proof

 context. Top-level ML bindings are stored within the proof context in

 a purely sequential fashion, disregarding the nested proof structure.

 ML bindings introduced by 'ML_prf' are discarded at the end of the

 proof.  [Poly/ML 5.2 or later]

 * Generic Toplevel.add_hook interface allows to analyze the result of

 transactions.  E.g. see src/Pure/ProofGeneral/proof_general_pgip.ML

 for theorem dependency output of transactions resulting in a new

 theory state.

 * Name bindings in higher specification mechanisms (notably

 LocalTheory.define, LocalTheory.note, and derived packages) are now

 formalized as type Name.binding, replacing old bstring.

 INCOMPATIBILITY, need to wrap strings via Name.binding function, see

 also Name.name_of.  Packages should pass name bindings given by the

 user to underlying specification mechanisms; this enables precise

 tracking of source positions, for example.

 * Result facts (from PureThy.note_thms, ProofContext.note_thms,

 LocalTheory.note etc.) now refer to the *full* internal name, not the

 bstring as before.  INCOMPATIBILITY, not detected by ML type-checking!

 * Rules and tactics that read instantiations (read_instantiate,

 res_inst_tac, thin_tac, subgoal_tac etc.) now demand a proper proof

 context, which is required for parsing and type-checking.  Moreover,

 the variables are specified as plain indexnames, not string encodings

 thereof.  INCOMPATIBILITY.

 * Disposed old type and term read functions (Sign.read_def_typ,

 Sign.read_typ, Sign.read_def_terms, Sign.read_term,

 Thm.read_def_cterms, Thm.read_cterm etc.).  INCOMPATIBILITY, should

 use regular Syntax.read_typ, Syntax.read_term, Syntax.read_typ_global,

 Syntax.read_term_global etc.; see also OldGoals.read_term as last

 resort for legacy applications.

 * Antiquotations: block-structured compilation context indicated by

 \<lbrace> ... \<rbrace>; additional antiquotation forms:

   @{let ?pat = term}                      - term abbreviation (HO matching)

   @{note name = fact}                     - fact abbreviation

   @{thm fact}                             - singleton fact (with attributes)

   @{thms fact}                            - general fact (with attributes)

   @{lemma prop by method}                 - singleton goal

   @{lemma prop by meth1 meth2}            - singleton goal

   @{lemma prop1 ... propN by method}      - general goal

   @{lemma prop1 ... propN by meth1 meth2} - general goal

   @{lemma (open) ...}                     - open derivation

 *** System ***

 * Multithreading for Poly/ML 5.1/5.2 is no longer supported, only for

 Poly/ML 5.2.1 or later.

 * The Isabelle "emacs" tool provides a specific interface to invoke

 Proof General / Emacs, with more explicit failure if that is not

 installed (the old isabelle-interface script silently falls back on

 isabelle-process).  The PROOFGENERAL_HOME setting determines the

 installation location of the Proof General distribution.

 * Isabelle/lib/classes/Pure.jar provides basic support to integrate

 the Isabelle process into a JVM/Scala application.  See

 Isabelle/lib/jedit/plugin for a minimal example.  (The obsolete Java

 process wrapper has been discontinued.)

 * Status messages (with exact source position information) are

 emitted, if proper markup print mode is enabled.  This allows

 user-interface components to provide detailed feedback on internal

 prover operations.

 * Homegrown Isabelle font with unicode layout, see Isabelle/lib/fonts.

 New in Isabelle2008 (June 2008)

 -------------------------------

 *** General ***

 * The Isabelle/Isar Reference Manual (isar-ref) has been reorganized

 and updated, with formally checked references as hyperlinks.

 * Theory loader: use_thy (and similar operations) no longer set the

 implicit ML context, which was occasionally hard to predict and in

 conflict with concurrency.  INCOMPATIBILITY, use ML within Isar which

 provides a proper context already.

 * Theory loader: old-style ML proof scripts being *attached* to a thy

 file are no longer supported.  INCOMPATIBILITY, regular 'uses' and

 'use' within a theory file will do the job.

 * Name space merge now observes canonical order, i.e. the second space

 is inserted into the first one, while existing entries in the first

 space take precedence.  INCOMPATIBILITY in rare situations, may try to

 swap theory imports.

 * Syntax: symbol \<chi> is now considered a letter.  Potential

 INCOMPATIBILITY in identifier syntax etc.

 * Outer syntax: string tokens no longer admit escaped white space,

 which was an accidental (undocumented) feature.  INCOMPATIBILITY, use

 white space without escapes.

 * Outer syntax: string tokens may contain arbitrary character codes

 specified via 3 decimal digits (as in SML).  E.g. "foo\095bar" for

 "foo_bar".

 *** Pure ***

 * Context-dependent token translations.  Default setup reverts locally

 fixed variables, and adds hilite markup for undeclared frees.

 * Unused theorems can be found using the new command 'unused_thms'.

 There are three ways of invoking it:

 (1) unused_thms

      Only finds unused theorems in the current theory.

 (2) unused_thms thy_1 ... thy_n -

      Finds unused theorems in the current theory and all of its ancestors,

      excluding the theories thy_1 ... thy_n and all of their ancestors.

 (3) unused_thms thy_1 ... thy_n - thy'_1 ... thy'_m

      Finds unused theorems in the theories thy'_1 ... thy'_m and all of

      their ancestors, excluding the theories thy_1 ... thy_n and all of

      their ancestors.

 In order to increase the readability of the list produced by

 unused_thms, theorems that have been created by a particular instance

 of a theory command such as 'inductive' or 'function' are considered

 to belong to the same "group", meaning that if at least one theorem in

 this group is used, the other theorems in the same group are no longer

 reported as unused.  Moreover, if all theorems in the group are

 unused, only one theorem in the group is displayed.

 Note that proof objects have to be switched on in order for

 unused_thms to work properly (i.e. !proofs must be >= 1, which is

 usually the case when using Proof General with the default settings).

 * Authentic naming of facts disallows ad-hoc overwriting of previous

 theorems within the same name space.  INCOMPATIBILITY, need to remove

 duplicate fact bindings, or even accidental fact duplications.  Note

 that tools may maintain dynamically scoped facts systematically, using

 PureThy.add_thms_dynamic.

 * Command 'hide' now allows to hide from "fact" name space as well.

 * Eliminated destructive theorem database, simpset, claset, and

 clasimpset.  Potential INCOMPATIBILITY, really need to observe linear

 update of theories within ML code.

 * Eliminated theory ProtoPure and CPure, leaving just one Pure theory.

 INCOMPATIBILITY, object-logics depending on former Pure require

 additional setup PureThy.old_appl_syntax_setup; object-logics

 depending on former CPure need to refer to Pure.

 * Commands 'use' and 'ML' are now purely functional, operating on

 theory/local_theory.  Removed former 'ML_setup' (on theory), use 'ML'

 instead.  Added 'ML_val' as mere diagnostic replacement for 'ML'.

 INCOMPATIBILITY.

 * Command 'setup': discontinued implicit version with ML reference.

 * Instantiation target allows for simultaneous specification of class

 instance operations together with an instantiation proof.

 Type-checking phase allows to refer to class operations uniformly.

 See src/HOL/Complex/Complex.thy for an Isar example and

 src/HOL/Library/Eval.thy for an ML example.

 * Indexing of literal facts: be more serious about including only

 facts from the visible specification/proof context, but not the

 background context (locale etc.).  Affects `prop` notation and method

 "fact".  INCOMPATIBILITY: need to name facts explicitly in rare

 situations.

 * Method "cases", "induct", "coinduct": removed obsolete/undocumented

 "(open)" option, which used to expose internal bound variables to the

 proof text.

 * Isar statements: removed obsolete case "rule_context".

 INCOMPATIBILITY, better use explicit fixes/assumes.

 * Locale proofs: default proof step now includes 'unfold_locales';

 hence 'proof' without argument may be used to unfold locale

 predicates.

 *** Document preparation ***

 * Simplified pdfsetup.sty: color/hyperref is used unconditionally for

 both pdf and dvi (hyperlinks usually work in xdvi as well); removed

 obsolete thumbpdf setup (contemporary PDF viewers do this on the

 spot); renamed link color from "darkblue" to "linkcolor" (default

 value unchanged, can be redefined via \definecolor); no longer sets

 "a4paper" option (unnecessary or even intrusive).

 * Antiquotation @{lemma A method} proves proposition A by the given

 method (either a method name or a method name plus (optional) method

 arguments in parentheses) and prints A just like @{prop A}.

 *** HOL ***

 * New primrec package.  Specification syntax conforms in style to

 definition/function/....  No separate induction rule is provided.  The

 "primrec" command distinguishes old-style and new-style specifications

 by syntax.  The former primrec package is now named OldPrimrecPackage.

 When adjusting theories, beware: constants stemming from new-style

 primrec specifications have authentic syntax.

 * Metis prover is now an order of magnitude faster, and also works

 with multithreading.

 * Metis: the maximum number of clauses that can be produced from a

 theorem is now given by the attribute max_clauses.  Theorems that

 exceed this number are ignored, with a warning printed.

 * Sledgehammer no longer produces structured proofs by default. To

 enable, declare [[sledgehammer_full = true]].  Attributes

 reconstruction_modulus, reconstruction_sorts renamed

 sledgehammer_modulus, sledgehammer_sorts.  INCOMPATIBILITY.

 * Method "induct_scheme" derives user-specified induction rules

 from well-founded induction and completeness of patterns. This factors

 out some operations that are done internally by the function package

 and makes them available separately.  See

 src/HOL/ex/Induction_Scheme.thy for examples.

 * More flexible generation of measure functions for termination

 proofs: Measure functions can be declared by proving a rule of the

 form "is_measure f" and giving it the [measure_function] attribute.

 The "is_measure" predicate is logically meaningless (always true), and

 just guides the heuristic.  To find suitable measure functions, the

 termination prover sets up the goal "is_measure ?f" of the appropriate

 type and generates all solutions by prolog-style backwards proof using

 the declared rules.

 This setup also deals with rules like 

   "is_measure f ==> is_measure (list_size f)"

 which accommodates nested datatypes that recurse through lists.

 Similar rules are predeclared for products and option types.

 * Turned the type of sets "'a set" into an abbreviation for "'a => bool"

   INCOMPATIBILITIES:

   - Definitions of overloaded constants on sets have to be replaced by

     definitions on => and bool.

   - Some definitions of overloaded operators on sets can now be proved

     using the definitions of the operators on => and bool.  Therefore,

     the following theorems have been renamed:

       subset_def   -> subset_eq

       psubset_def  -> psubset_eq

       set_diff_def -> set_diff_eq

       Compl_def    -> Compl_eq

       Sup_set_def  -> Sup_set_eq

       Inf_set_def  -> Inf_set_eq

       sup_set_def  -> sup_set_eq

       inf_set_def  -> inf_set_eq

   - Due to the incompleteness of the HO unification algorithm, some

     rules such as subst may require manual instantiation, if some of

     the unknowns in the rule is a set.

   - Higher order unification and forward proofs:

     The proof pattern

       have "P (S::'a set)" <...>

       then have "EX S. P S" ..

     no longer works (due to the incompleteness of the HO unification

     algorithm) and must be replaced by the pattern

       have "EX S. P S"

       proof

         show "P S" <...>

       qed

   - Calculational reasoning with subst (or similar rules):

     The proof pattern

       have "P (S::'a set)" <...>

       also have "S = T" <...>

       finally have "P T" .

     no longer works (for similar reasons as the previous example) and

     must be replaced by something like

       have "P (S::'a set)" <...>

       moreover have "S = T" <...>

       ultimately have "P T" by simp

   - Tactics or packages written in ML code:

     Code performing pattern matching on types via

       Type ("set", [T]) => ...

     must be rewritten. Moreover, functions like strip_type or

     binder_types no longer return the right value when applied to a

     type of the form

       T1 => ... => Tn => U => bool

     rather than

       T1 => ... => Tn => U set

 * Merged theories Wellfounded_Recursion, Accessible_Part and

 Wellfounded_Relations to theory Wellfounded.

 * Explicit class "eq" for executable equality.  INCOMPATIBILITY.

 * Class finite no longer treats UNIV as class parameter.  Use class

 enum from theory Library/Enum instead to achieve a similar effect.

 INCOMPATIBILITY.

 * Theory List: rule list_induct2 now has explicitly named cases "Nil"

 and "Cons".  INCOMPATIBILITY.

 * HOL (and FOL): renamed variables in rules imp_elim and swap.

 Potential INCOMPATIBILITY.

 * Theory Product_Type: duplicated lemmas split_Pair_apply and

 injective_fst_snd removed, use split_eta and prod_eqI instead.

 Renamed upd_fst to apfst and upd_snd to apsnd.  INCOMPATIBILITY.

 * Theory Nat: removed redundant lemmas that merely duplicate lemmas of

 the same name in theory Orderings:

   less_trans

   less_linear

   le_imp_less_or_eq

   le_less_trans

   less_le_trans

   less_not_sym

   less_asym

 Renamed less_imp_le to less_imp_le_nat, and less_irrefl to

 less_irrefl_nat.  Potential INCOMPATIBILITY due to more general types

 and different variable names.

 * Library/Option_ord.thy: Canonical order on option type.

 * Library/RBT.thy: Red-black trees, an efficient implementation of

 finite maps.

 * Library/Countable.thy: Type class for countable types.

 * Theory Int: The representation of numerals has changed.  The infix

 operator BIT and the bit datatype with constructors B0 and B1 have

 disappeared.  INCOMPATIBILITY, use "Int.Bit0 x" and "Int.Bit1 y" in

 place of "x BIT bit.B0" and "y BIT bit.B1", respectively.  Theorems

 involving BIT, B0, or B1 have been renamed with "Bit0" or "Bit1"

 accordingly.

 * Theory Nat: definition of <= and < on natural numbers no longer

 depend on well-founded relations.  INCOMPATIBILITY.  Definitions

 le_def and less_def have disappeared.  Consider lemmas not_less

 [symmetric, where ?'a = nat] and less_eq [symmetric] instead.

 * Theory Finite_Set: locales ACf, ACe, ACIf, ACIfSL and ACIfSLlin

 (whose purpose mainly is for various fold_set functionals) have been

 abandoned in favor of the existing algebraic classes

 ab_semigroup_mult, comm_monoid_mult, ab_semigroup_idem_mult,

 lower_semilattice (resp. upper_semilattice) and linorder.

 INCOMPATIBILITY.

 * Theory Transitive_Closure: induct and cases rules now declare proper

 case_names ("base" and "step").  INCOMPATIBILITY.

 * Theorem Inductive.lfp_ordinal_induct generalized to complete

 lattices.  The form set-specific version is available as

 Inductive.lfp_ordinal_induct_set.

 * Renamed theorems "power.simps" to "power_int.simps".

 INCOMPATIBILITY.

 * Class semiring_div provides basic abstract properties of semirings

 with division and modulo operations.  Subsumes former class dvd_mod.

 * Merged theories IntDef, Numeral and IntArith into unified theory

 Int.  INCOMPATIBILITY.

 * Theory Library/Code_Index: type "index" now represents natural

 numbers rather than integers.  INCOMPATIBILITY.

 * New class "uminus" with operation "uminus" (split of from class

 "minus" which now only has operation "minus", binary).

 INCOMPATIBILITY.

 * Constants "card", "internal_split", "option_map" now with authentic

 syntax.  INCOMPATIBILITY.

 * Definitions subset_def, psubset_def, set_diff_def, Compl_def,

 le_bool_def, less_bool_def, le_fun_def, less_fun_def, inf_bool_def,

 sup_bool_def, Inf_bool_def, Sup_bool_def, inf_fun_def, sup_fun_def,

 Inf_fun_def, Sup_fun_def, inf_set_def, sup_set_def, Inf_set_def,

 Sup_set_def, le_def, less_def, option_map_def now with object

 equality.  INCOMPATIBILITY.

 * Records. Removed K_record, and replaced it by pure lambda term

 %x. c. The simplifier setup is now more robust against eta expansion.

 INCOMPATIBILITY: in cases explicitly referring to K_record.

 * Library/Multiset: {#a, b, c#} abbreviates {#a#} + {#b#} + {#c#}.

 * Library/ListVector: new theory of arithmetic vector operations.

 * Library/Order_Relation: new theory of various orderings as sets of

 pairs.  Defines preorders, partial orders, linear orders and

 well-orders on sets and on types.

 *** ZF ***

 * Renamed some theories to allow to loading both ZF and HOL in the

 same session:

   Datatype  -> Datatype_ZF

   Inductive -> Inductive_ZF

   Int       -> Int_ZF

   IntDiv    -> IntDiv_ZF

   Nat       -> Nat_ZF

   List      -> List_ZF

   Main      -> Main_ZF

 INCOMPATIBILITY: ZF theories that import individual theories below

 Main might need to be adapted.  Regular theory Main is still

 available, as trivial extension of Main_ZF.

 *** ML ***

 * ML within Isar: antiquotation @{const name} or @{const

 name(typargs)} produces statically-checked Const term.

 * Functor NamedThmsFun: data is available to the user as dynamic fact

 (of the same name).  Removed obsolete print command.

 * Removed obsolete "use_legacy_bindings" function.

 * The ``print mode'' is now a thread-local value derived from a global

 template (the former print_mode reference), thus access becomes

 non-critical.  The global print_mode reference is for session

 management only; user-code should use print_mode_value,

 print_mode_active, PrintMode.setmp etc.  INCOMPATIBILITY.

 * Functions system/system_out provide a robust way to invoke external

 shell commands, with propagation of interrupts (requires Poly/ML 5.2).

 Do not use OS.Process.system etc. from the basis library!

 *** System ***

 * Default settings: PROOFGENERAL_OPTIONS no longer impose xemacs ---

 in accordance with Proof General 3.7, which prefers GNU emacs.

 * isatool tty runs Isabelle process with plain tty interaction;

 optional line editor may be specified via ISABELLE_LINE_EDITOR

 setting, the default settings attempt to locate "ledit" and "rlwrap".

 * isatool browser now works with Cygwin as well, using general

 "javapath" function defined in Isabelle process environment.

 * YXML notation provides a simple and efficient alternative to

 standard XML transfer syntax.  See src/Pure/General/yxml.ML and

 isatool yxml as described in the Isabelle system manual.

 * JVM class isabelle.IsabelleProcess (located in Isabelle/lib/classes)

 provides general wrapper for managing an Isabelle process in a robust

 fashion, with ``cooked'' output from stdin/stderr.

 * Rudimentary Isabelle plugin for jEdit (see Isabelle/lib/jedit),

 based on Isabelle/JVM process wrapper (see Isabelle/lib/classes).

 * Removed obsolete THIS_IS_ISABELLE_BUILD feature.  NB: the documented

 way of changing the user's settings is via

 ISABELLE_HOME_USER/etc/settings, which is a fully featured bash

 script.

 * Multithreading.max_threads := 0 refers to the number of actual CPU

 cores of the underlying machine, which is a good starting point for

 optimal performance tuning.  The corresponding usedir option -M allows

 "max" as an alias for "0".  WARNING: does not work on certain versions

 of Mac OS (with Poly/ML 5.1).

 * isabelle-process: non-ML sessions are run with "nice", to reduce the

 adverse effect of Isabelle flooding interactive front-ends (notably

 ProofGeneral / XEmacs).

 New in Isabelle2007 (November 2007)

 -----------------------------------

 *** General ***

 * More uniform information about legacy features, notably a

 warning/error of "Legacy feature: ...", depending on the state of the

 tolerate_legacy_features flag (default true). FUTURE INCOMPATIBILITY:

 legacy features will disappear eventually.

 * Theory syntax: the header format ``theory A = B + C:'' has been

 discontinued in favour of ``theory A imports B C begin''.  Use isatool

 fixheaders to convert existing theory files.  INCOMPATIBILITY.

 * Theory syntax: the old non-Isar theory file format has been

 discontinued altogether.  Note that ML proof scripts may still be used

 with Isar theories; migration is usually quite simple with the ML

 function use_legacy_bindings.  INCOMPATIBILITY.

 * Theory syntax: some popular names (e.g. 'class', 'declaration',

 'fun', 'help', 'if') are now keywords.  INCOMPATIBILITY, use double

 quotes.

 * Theory loader: be more serious about observing the static theory

 header specifications (including optional directories), but not the

 accidental file locations of previously successful loads.  The strict

 update policy of former update_thy is now already performed by

 use_thy, so the former has been removed; use_thys updates several

 theories simultaneously, just as 'imports' within a theory header

 specification, but without merging the results.  Potential

 INCOMPATIBILITY: may need to refine theory headers and commands

 ROOT.ML which depend on load order.

 * Theory loader: optional support for content-based file

 identification, instead of the traditional scheme of full physical

 path plus date stamp; configured by the ISABELLE_FILE_IDENT setting

 (cf. the system manual).  The new scheme allows to work with

 non-finished theories in persistent session images, such that source

 files may be moved later on without requiring reloads.

 * Theory loader: old-style ML proof scripts being *attached* to a thy

 file (with the same base name as the theory) are considered a legacy

 feature, which will disappear eventually. Even now, the theory loader

 no longer maintains dependencies on such files.

 * Syntax: the scope for resolving ambiguities via type-inference is

 now limited to individual terms, instead of whole simultaneous

 specifications as before. This greatly reduces the complexity of the

 syntax module and improves flexibility by separating parsing and

 type-checking. INCOMPATIBILITY: additional type-constraints (explicit

 'fixes' etc.) are required in rare situations.

 * Syntax: constants introduced by new-style packages ('definition',

 'abbreviation' etc.) are passed through the syntax module in

 ``authentic mode''. This means that associated mixfix annotations

 really stick to such constants, independently of potential name space

 ambiguities introduced later on. INCOMPATIBILITY: constants in parse

 trees are represented slightly differently, may need to adapt syntax

 translations accordingly. Use CONST marker in 'translations' and

 @{const_syntax} antiquotation in 'parse_translation' etc.

 * Legacy goal package: reduced interface to the bare minimum required

 to keep existing proof scripts running.  Most other user-level

 functions are now part of the OldGoals structure, which is *not* open

 by default (consider isatool expandshort before open OldGoals).

 Removed top_sg, prin, printyp, pprint_term/typ altogether, because

 these tend to cause confusion about the actual goal (!) context being

 used here, which is not necessarily the same as the_context().

 * Command 'find_theorems': supports "*" wild-card in "name:"

 criterion; "with_dups" option.  Certain ProofGeneral versions might

 support a specific search form (see ProofGeneral/CHANGES).

 * The ``prems limit'' option (cf. ProofContext.prems_limit) is now -1

 by default, which means that "prems" (and also "fixed variables") are

 suppressed from proof state output.  Note that the ProofGeneral

 settings mechanism allows to change and save options persistently, but

 older versions of Isabelle will fail to start up if a negative prems

 limit is imposed.

 * Local theory targets may be specified by non-nested blocks of

 ``context/locale/class ... begin'' followed by ``end''.  The body may

 contain definitions, theorems etc., including any derived mechanism

 that has been implemented on top of these primitives.  This concept

 generalizes the existing ``theorem (in ...)'' towards more versatility

 and scalability.

 * Proof General interface: proper undo of final 'end' command;

 discontinued Isabelle/classic mode (ML proof scripts).

 *** Document preparation ***

 * Added antiquotation @{theory name} which prints the given name,

 after checking that it refers to a valid ancestor theory in the

 current context.

 * Added antiquotations @{ML_type text} and @{ML_struct text} which

 check the given source text as ML type/structure, printing verbatim.

 * Added antiquotation @{abbrev "c args"} which prints the abbreviation

 "c args == rhs" given in the current context.  (Any number of

 arguments may be given on the LHS.)

 *** Pure ***

 * The 'class' package offers a combination of axclass and locale to

 achieve Haskell-like type classes in Isabelle.  Definitions and

 theorems within a class context produce both relative results (with

 implicit parameters according to the locale context), and polymorphic

 constants with qualified polymorphism (according to the class

 context).  Within the body context of a 'class' target, a separate

 syntax layer ("user space type system") takes care of converting

 between global polymorphic consts and internal locale representation.

 See src/HOL/ex/Classpackage.thy for examples (as well as main HOL).

 "isatool doc classes" provides a tutorial.

 * Generic code generator framework allows to generate executable

 code for ML and Haskell (including Isabelle classes).  A short usage

 sketch:

     internal compilation:

         export_code <list of constants (term syntax)> in SML

     writing SML code to a file:

         export_code <list of constants (term syntax)> in SML <filename>

     writing OCaml code to a file:

         export_code <list of constants (term syntax)> in OCaml <filename>

     writing Haskell code to a bunch of files:

         export_code <list of constants (term syntax)> in Haskell <filename>

     evaluating closed propositions to True/False using code generation:

         method ``eval''

 Reasonable default setup of framework in HOL.

 Theorem attributs for selecting and transforming function equations theorems:

     [code fun]:        select a theorem as function equation for a specific constant

     [code fun del]:    deselect a theorem as function equation for a specific constant

     [code inline]:     select an equation theorem for unfolding (inlining) in place

     [code inline del]: deselect an equation theorem for unfolding (inlining) in place

 User-defined serializations (target in {SML, OCaml, Haskell}):

     code_const <and-list of constants (term syntax)>

       {(target) <and-list of const target syntax>}+

     code_type <and-list of type constructors>

       {(target) <and-list of type target syntax>}+

     code_instance <and-list of instances>

       {(target)}+

         where instance ::= <type constructor> :: <class>

     code_class <and_list of classes>

       {(target) <and-list of class target syntax>}+

         where class target syntax ::= <class name> {where {<classop> == <target syntax>}+}?

 code_instance and code_class only are effective to target Haskell.

 For example usage see src/HOL/ex/Codegenerator.thy and

 src/HOL/ex/Codegenerator_Pretty.thy.  A separate tutorial on code

 generation from Isabelle/HOL theories is available via "isatool doc

 codegen".

 * Code generator: consts in 'consts_code' Isar commands are now

 referred to by usual term syntax (including optional type

 annotations).

 * Command 'no_translations' removes translation rules from theory

 syntax.

 * Overloaded definitions are now actually checked for acyclic

 dependencies.  The overloading scheme is slightly more general than

 that of Haskell98, although Isabelle does not demand an exact

 correspondence to type class and instance declarations.

 INCOMPATIBILITY, use ``defs (unchecked overloaded)'' to admit more

 exotic versions of overloading -- at the discretion of the user!

 Polymorphic constants are represented via type arguments, i.e. the

 instantiation that matches an instance against the most general

 declaration given in the signature.  For example, with the declaration

 c :: 'a => 'a => 'a, an instance c :: nat => nat => nat is represented

 as c(nat).  Overloading is essentially simultaneous structural

 recursion over such type arguments.  Incomplete specification patterns

 impose global constraints on all occurrences, e.g. c('a * 'a) on the

 LHS means that more general c('a * 'b) will be disallowed on any RHS.

 Command 'print_theory' outputs the normalized system of recursive

 equations, see section "definitions".

 * Configuration options are maintained within the theory or proof

 context (with name and type bool/int/string), providing a very simple

 interface to a poor-man's version of general context data.  Tools may

 declare options in ML (e.g. using Attrib.config_int) and then refer to

 these values using Config.get etc.  Users may change options via an

 associated attribute of the same name.  This form of context

 declaration works particularly well with commands 'declare' or

 'using', for example ``declare [[foo = 42]]''.  Thus it has become

 very easy to avoid global references, which would not observe Isar

 toplevel undo/redo and fail to work with multithreading.

 Various global ML references of Pure and HOL have been turned into

 configuration options:

   Unify.search_bound		unify_search_bound

   Unify.trace_bound		unify_trace_bound

   Unify.trace_simp		unify_trace_simp

   Unify.trace_types		unify_trace_types

   Simplifier.simp_depth_limit	simp_depth_limit

   Blast.depth_limit		blast_depth_limit

   DatatypeProp.dtK		datatype_distinctness_limit

   fast_arith_neq_limit  	fast_arith_neq_limit

   fast_arith_split_limit	fast_arith_split_limit

 * Named collections of theorems may be easily installed as context

 data using the functor NamedThmsFun (see also

 src/Pure/Tools/named_thms.ML).  The user may add or delete facts via

 attributes; there is also a toplevel print command.  This facility is

 just a common case of general context data, which is the preferred way

 for anything more complex than just a list of facts in canonical

 order.

 * Isar: command 'declaration' augments a local theory by generic

 declaration functions written in ML.  This enables arbitrary content

 being added to the context, depending on a morphism that tells the

 difference of the original declaration context wrt. the application

 context encountered later on.

 * Isar: proper interfaces for simplification procedures.  Command

 'simproc_setup' declares named simprocs (with match patterns, and body

 text in ML).  Attribute "simproc" adds/deletes simprocs in the current

 context.  ML antiquotation @{simproc name} retrieves named simprocs.

 * Isar: an extra pair of brackets around attribute declarations

 abbreviates a theorem reference involving an internal dummy fact,

 which will be ignored later --- only the effect of the attribute on

 the background context will persist.  This form of in-place

 declarations is particularly useful with commands like 'declare' and

 'using', for example ``have A using [[simproc a]] by simp''.

 * Isar: method "assumption" (and implicit closing of subproofs) now

 takes simple non-atomic goal assumptions into account: after applying

 an assumption as a rule the resulting subgoals are solved by atomic

 assumption steps.  This is particularly useful to finish 'obtain'

 goals, such as "!!x. (!!x. P x ==> thesis) ==> P x ==> thesis",

 without referring to the original premise "!!x. P x ==> thesis" in the

 Isar proof context.  POTENTIAL INCOMPATIBILITY: method "assumption" is

 more permissive.

 * Isar: implicit use of prems from the Isar proof context is

 considered a legacy feature.  Common applications like ``have A .''

 may be replaced by ``have A by fact'' or ``note `A`''.  In general,

 referencing facts explicitly here improves readability and

 maintainability of proof texts.

 * Isar: improper proof element 'guess' is like 'obtain', but derives

 the obtained context from the course of reasoning!  For example:

   assume "EX x y. A x & B y"   -- "any previous fact"

   then guess x and y by clarify

 This technique is potentially adventurous, depending on the facts and

 proof tools being involved here.

 * Isar: known facts from the proof context may be specified as literal

 propositions, using ASCII back-quote syntax.  This works wherever

 named facts used to be allowed so far, in proof commands, proof

 methods, attributes etc.  Literal facts are retrieved from the context

 according to unification of type and term parameters.  For example,

 provided that "A" and "A ==> B" and "!!x. P x ==> Q x" are known

 theorems in the current context, then these are valid literal facts:

 `A` and `A ==> B` and `!!x. P x ==> Q x" as well as `P a ==> Q a` etc.

 There is also a proof method "fact" which does the same composition

 for explicit goal states, e.g. the following proof texts coincide with

 certain special cases of literal facts:

   have "A" by fact                 ==  note `A`

   have "A ==> B" by fact           ==  note `A ==> B`

   have "!!x. P x ==> Q x" by fact  ==  note `!!x. P x ==> Q x`

   have "P a ==> Q a" by fact       ==  note `P a ==> Q a`

 * Isar: ":" (colon) is no longer a symbolic identifier character in

 outer syntax.  Thus symbolic identifiers may be used without

 additional white space in declarations like this: ``assume *: A''.

 * Isar: 'print_facts' prints all local facts of the current context,

 both named and unnamed ones.

 * Isar: 'def' now admits simultaneous definitions, e.g.:

   def x == "t" and y == "u"

 * Isar: added command 'unfolding', which is structurally similar to

 'using', but affects both the goal state and facts by unfolding given

 rewrite rules.  Thus many occurrences of the 'unfold' method or

 'unfolded' attribute may be replaced by first-class proof text.

 * Isar: methods 'unfold' / 'fold', attributes 'unfolded' / 'folded',

 and command 'unfolding' now all support object-level equalities

 (potentially conditional).  The underlying notion of rewrite rule is

 analogous to the 'rule_format' attribute, but *not* that of the

 Simplifier (which is usually more generous).

 * Isar: the new attribute [rotated n] (default n = 1) rotates the

 premises of a theorem by n. Useful in conjunction with drule.

 * Isar: the goal restriction operator [N] (default N = 1) evaluates a

 method expression within a sandbox consisting of the first N

 sub-goals, which need to exist.  For example, ``simp_all [3]''

 simplifies the first three sub-goals, while (rule foo, simp_all)[]

 simplifies all new goals that emerge from applying rule foo to the

 originally first one.

 * Isar: schematic goals are no longer restricted to higher-order

 patterns; e.g. ``lemma "?P(?x)" by (rule TrueI)'' now works as

 expected.

 * Isar: the conclusion of a long theorem statement is now either

 'shows' (a simultaneous conjunction, as before), or 'obtains'

 (essentially a disjunction of cases with local parameters and

 assumptions).  The latter allows to express general elimination rules

 adequately; in this notation common elimination rules look like this:

   lemma exE:    -- "EX x. P x ==> (!!x. P x ==> thesis) ==> thesis"

     assumes "EX x. P x"

     obtains x where "P x"

   lemma conjE:  -- "A & B ==> (A ==> B ==> thesis) ==> thesis"

     assumes "A & B"

     obtains A and B

   lemma disjE:  -- "A | B ==> (A ==> thesis) ==> (B ==> thesis) ==> thesis"

     assumes "A | B"

     obtains

       A

     | B

 The subsequent classical rules even refer to the formal "thesis"

 explicitly:

   lemma classical:     -- "(~ thesis ==> thesis) ==> thesis"

     obtains "~ thesis"

   lemma Peirce's_Law:  -- "((thesis ==> something) ==> thesis) ==> thesis"

     obtains "thesis ==> something"

 The actual proof of an 'obtains' statement is analogous to that of the

 Isar proof element 'obtain', only that there may be several cases.

 Optional case names may be specified in parentheses; these will be

 available both in the present proof and as annotations in the

 resulting rule, for later use with the 'cases' method (cf. attribute

 case_names).

 * Isar: the assumptions of a long theorem statement are available as

 "assms" fact in the proof context.  This is more appropriate than the

 (historical) "prems", which refers to all assumptions of the current

 context, including those from the target locale, proof body etc.

 * Isar: 'print_statement' prints theorems from the current theory or

 proof context in long statement form, according to the syntax of a

 top-level lemma.

 * Isar: 'obtain' takes an optional case name for the local context

 introduction rule (default "that").

 * Isar: removed obsolete 'concl is' patterns.  INCOMPATIBILITY, use

 explicit (is "_ ==> ?foo") in the rare cases where this still happens

 to occur.

 * Pure: syntax "CONST name" produces a fully internalized constant

 according to the current context.  This is particularly useful for

 syntax translations that should refer to internal constant

 representations independently of name spaces.

 * Pure: syntax constant for foo (binder "FOO ") is called "foo_binder"

 instead of "FOO ". This allows multiple binder declarations to coexist

 in the same context.  INCOMPATIBILITY.

 * Isar/locales: 'notation' provides a robust interface to the 'syntax'

 primitive that also works in a locale context (both for constants and

 fixed variables). Type declaration and internal syntactic representation

 of given constants retrieved from the context. Likewise, the

 'no_notation' command allows to remove given syntax annotations from the

 current context.

 * Isar/locales: new derived specification elements 'axiomatization',

 'definition', 'abbreviation', which support type-inference, admit

 object-level specifications (equality, equivalence).  See also the

 isar-ref manual.  Examples:

   axiomatization

     eq  (infix "===" 50) where

     eq_refl: "x === x" and eq_subst: "x === y ==> P x ==> P y"

   definition "f x y = x + y + 1"

   definition g where "g x = f x x"

   abbreviation

     neq  (infix "=!=" 50) where

     "x =!= y == ~ (x === y)"

 These specifications may be also used in a locale context.  Then the

 constants being introduced depend on certain fixed parameters, and the

 constant name is qualified by the locale base name.  An internal

 abbreviation takes care for convenient input and output, making the

 parameters implicit and using the original short name.  See also

 src/HOL/ex/Abstract_NAT.thy for an example of deriving polymorphic

 entities from a monomorphic theory.

 Presently, abbreviations are only available 'in' a target locale, but

 not inherited by general import expressions.  Also note that

 'abbreviation' may be used as a type-safe replacement for 'syntax' +

 'translations' in common applications.  The "no_abbrevs" print mode

 prevents folding of abbreviations in term output.

 Concrete syntax is attached to specified constants in internal form,

 independently of name spaces.  The parse tree representation is

 slightly different -- use 'notation' instead of raw 'syntax', and

 'translations' with explicit "CONST" markup to accommodate this.

 * Pure/Isar: unified syntax for new-style specification mechanisms

 (e.g.  'definition', 'abbreviation', or 'inductive' in HOL) admits

 full type inference and dummy patterns ("_").  For example:

   definition "K x _ = x"

   inductive conj for A B

   where "A ==> B ==> conj A B"

 * Pure: command 'print_abbrevs' prints all constant abbreviations of

 the current context.  Print mode "no_abbrevs" prevents inversion of

 abbreviations on output.

 * Isar/locales: improved parameter handling: use of locales "var" and

 "struct" no longer necessary; - parameter renamings are no longer

 required to be injective.  For example, this allows to define

 endomorphisms as locale endom = homom mult mult h.

 * Isar/locales: changed the way locales with predicates are defined.

 Instead of accumulating the specification, the imported expression is

 now an interpretation.  INCOMPATIBILITY: different normal form of

 locale expressions.  In particular, in interpretations of locales with

 predicates, goals repesenting already interpreted fragments are not

 removed automatically.  Use methods `intro_locales' and

 `unfold_locales'; see below.

 * Isar/locales: new methods `intro_locales' and `unfold_locales'

 provide backward reasoning on locales predicates.  The methods are

 aware of interpretations and discharge corresponding goals.

 `intro_locales' is less aggressive then `unfold_locales' and does not

 unfold predicates to assumptions.

 * Isar/locales: the order in which locale fragments are accumulated

 has changed.  This enables to override declarations from fragments due

 to interpretations -- for example, unwanted simp rules.

 * Isar/locales: interpretation in theories and proof contexts has been

 extended.  One may now specify (and prove) equations, which are

 unfolded in interpreted theorems.  This is useful for replacing

 defined concepts (constants depending on locale parameters) by

 concepts already existing in the target context.  Example:

   interpretation partial_order ["op <= :: [int, int] => bool"]

     where "partial_order.less (op <=) (x::int) y = (x < y)"

 Typically, the constant `partial_order.less' is created by a

 definition specification element in the context of locale

 partial_order.

 * Method "induct": improved internal context management to support

 local fixes and defines on-the-fly. Thus explicit meta-level

 connectives !!  and ==> are rarely required anymore in inductive goals

 (using object-logic connectives for this purpose has been long

 obsolete anyway). Common proof patterns are explained in

 src/HOL/Induct/Common_Patterns.thy, see also

 src/HOL/Isar_examples/Puzzle.thy and src/HOL/Lambda for realistic

 examples.

 * Method "induct": improved handling of simultaneous goals. Instead of

 introducing object-level conjunction, the statement is now split into

 several conclusions, while the corresponding symbolic cases are nested

 accordingly. INCOMPATIBILITY, proofs need to be structured explicitly,

 see src/HOL/Induct/Common_Patterns.thy, for example.

 * Method "induct": mutual induction rules are now specified as a list

 of rule sharing the same induction cases. HOL packages usually provide

 foo_bar.inducts for mutually defined items foo and bar (e.g. inductive

 predicates/sets or datatypes). INCOMPATIBILITY, users need to specify

 mutual induction rules differently, i.e. like this:

   (induct rule: foo_bar.inducts)

   (induct set: foo bar)

   (induct pred: foo bar)

   (induct type: foo bar)

 The ML function ProjectRule.projections turns old-style rules into the

 new format.

 * Method "coinduct": dual of induction, see

 src/HOL/Library/Coinductive_List.thy for various examples.

 * Method "cases", "induct", "coinduct": the ``(open)'' option is

 considered a legacy feature.

 * Attribute "symmetric" produces result with standardized schematic

 variables (index 0).  Potential INCOMPATIBILITY.

 * Simplifier: by default the simplifier trace only shows top level

 rewrites now. That is, trace_simp_depth_limit is set to 1 by

 default. Thus there is less danger of being flooded by the trace. The

 trace indicates where parts have been suppressed.

 * Provers/classical: removed obsolete classical version of elim_format

 attribute; classical elim/dest rules are now treated uniformly when

 manipulating the claset.

 * Provers/classical: stricter checks to ensure that supplied intro,

 dest and elim rules are well-formed; dest and elim rules must have at

 least one premise.

 * Provers/classical: attributes dest/elim/intro take an optional

 weight argument for the rule (just as the Pure versions).  Weights are

 ignored by automated tools, but determine the search order of single

 rule steps.

 * Syntax: input syntax now supports dummy variable binding "%_. b",

 where the body does not mention the bound variable.  Note that dummy

 patterns implicitly depend on their context of bounds, which makes

 "{_. _}" match any set comprehension as expected.  Potential

 INCOMPATIBILITY -- parse translations need to cope with syntactic

 constant "_idtdummy" in the binding position.

 * Syntax: removed obsolete syntactic constant "_K" and its associated

 parse translation.  INCOMPATIBILITY -- use dummy abstraction instead,

 for example "A -> B" => "Pi A (%_. B)".

 * Pure: 'class_deps' command visualizes the subclass relation, using

 the graph browser tool.

 * Pure: 'print_theory' now suppresses certain internal declarations by

 default; use '!' option for full details.

 *** HOL ***

 * Method "metis" proves goals by applying the Metis general-purpose

 resolution prover (see also http://gilith.com/software/metis/).

 Examples are in the directory MetisExamples.  WARNING: the

 Isabelle/HOL-Metis integration does not yet work properly with

 multi-threading.

 * Command 'sledgehammer' invokes external automatic theorem provers as

 background processes.  It generates calls to the "metis" method if

 successful. These can be pasted into the proof.  Users do not have to

 wait for the automatic provers to return.  WARNING: does not really

 work with multi-threading.

 * New "auto_quickcheck" feature tests outermost goal statements for

 potential counter-examples.  Controlled by ML references

 auto_quickcheck (default true) and auto_quickcheck_time_limit (default

 5000 milliseconds).  Fails silently if statements is outside of

 executable fragment, or any other codgenerator problem occurs.

 * New constant "undefined" with axiom "undefined x = undefined".

 * Added class "HOL.eq", allowing for code generation with polymorphic

 equality.

 * Some renaming of class constants due to canonical name prefixing in

 the new 'class' package:

     HOL.abs ~> HOL.abs_class.abs

     HOL.divide ~> HOL.divide_class.divide

     0 ~> HOL.zero_class.zero

     1 ~> HOL.one_class.one

     op + ~> HOL.plus_class.plus

     op - ~> HOL.minus_class.minus

     uminus ~> HOL.minus_class.uminus

     op * ~> HOL.times_class.times

     op < ~> HOL.ord_class.less

     op <= > HOL.ord_class.less_eq

     Nat.power ~> Power.power_class.power

     Nat.size ~> Nat.size_class.size

     Numeral.number_of ~> Numeral.number_class.number_of

     FixedPoint.Inf ~> Lattices.complete_lattice_class.Inf

     FixedPoint.Sup ~> Lattices.complete_lattice_class.Sup

     Orderings.min ~> Orderings.ord_class.min

     Orderings.max ~> Orderings.ord_class.max

     Divides.op div ~> Divides.div_class.div

     Divides.op mod ~> Divides.div_class.mod

     Divides.op dvd ~> Divides.div_class.dvd

 INCOMPATIBILITY.  Adaptions may be required in the following cases:

 a) User-defined constants using any of the names "plus", "minus",

 "times", "less" or "less_eq". The standard syntax translations for

 "+", "-" and "*" may go wrong.  INCOMPATIBILITY: use more specific

 names.

 b) Variables named "plus", "minus", "times", "less", "less_eq"

 INCOMPATIBILITY: use more specific names.

 c) Permutative equations (e.g. "a + b = b + a")

 Since the change of names also changes the order of terms, permutative

 rewrite rules may get applied in a different order. Experience shows

 that this is rarely the case (only two adaptions in the whole Isabelle

 distribution).  INCOMPATIBILITY: rewrite proofs

 d) ML code directly refering to constant names

 This in general only affects hand-written proof tactics, simprocs and

 so on.  INCOMPATIBILITY: grep your sourcecode and replace names.

 Consider using @{const_name} antiquotation.

 * New class "default" with associated constant "default".

 * Function "sgn" is now overloaded and available on int, real, complex

 (and other numeric types), using class "sgn".  Two possible defs of

 sgn are given as equational assumptions in the classes sgn_if and

 sgn_div_norm; ordered_idom now also inherits from sgn_if.

 INCOMPATIBILITY.

 * Locale "partial_order" now unified with class "order" (cf. theory

 Orderings), added parameter "less".  INCOMPATIBILITY.

 * Renamings in classes "order" and "linorder": facts "refl", "trans" and

 "cases" to "order_refl", "order_trans" and "linorder_cases", to avoid

 clashes with HOL "refl" and "trans".  INCOMPATIBILITY.

 * Classes "order" and "linorder": potential INCOMPATIBILITY due to

 changed order of proof goals in instance proofs.

 * The transitivity reasoner for partial and linear orders is set up

 for classes "order" and "linorder".  Instances of the reasoner are available

 in all contexts importing or interpreting the corresponding locales.

 Method "order" invokes the reasoner separately; the reasoner

 is also integrated with the Simplifier as a solver.  Diagnostic

 command 'print_orders' shows the available instances of the reasoner

 in the current context.

 * Localized monotonicity predicate in theory "Orderings"; integrated

 lemmas max_of_mono and min_of_mono with this predicate.

 INCOMPATIBILITY.

 * Formulation of theorem "dense" changed slightly due to integration

 with new class dense_linear_order.

 * Uniform lattice theory development in HOL.

     constants "meet" and "join" now named "inf" and "sup"

     constant "Meet" now named "Inf"

     classes "meet_semilorder" and "join_semilorder" now named

       "lower_semilattice" and "upper_semilattice"

     class "lorder" now named "lattice"

     class "comp_lat" now named "complete_lattice"

     Instantiation of lattice classes allows explicit definitions

     for "inf" and "sup" operations (or "Inf" and "Sup" for complete lattices).

   INCOMPATIBILITY.  Theorem renames:

     meet_left_le            ~> inf_le1

     meet_right_le           ~> inf_le2

     join_left_le            ~> sup_ge1

     join_right_le           ~> sup_ge2

     meet_join_le            ~> inf_sup_ord

     le_meetI                ~> le_infI

     join_leI                ~> le_supI

     le_meet                 ~> le_inf_iff

     le_join                 ~> ge_sup_conv

     meet_idempotent         ~> inf_idem

     join_idempotent         ~> sup_idem

     meet_comm               ~> inf_commute

     join_comm               ~> sup_commute

     meet_leI1               ~> le_infI1

     meet_leI2               ~> le_infI2

     le_joinI1               ~> le_supI1

     le_joinI2               ~> le_supI2

     meet_assoc              ~> inf_assoc

     join_assoc              ~> sup_assoc

     meet_left_comm          ~> inf_left_commute

     meet_left_idempotent    ~> inf_left_idem

     join_left_comm          ~> sup_left_commute

     join_left_idempotent    ~> sup_left_idem

     meet_aci                ~> inf_aci

     join_aci                ~> sup_aci

     le_def_meet             ~> le_iff_inf

     le_def_join             ~> le_iff_sup

     join_absorp2            ~> sup_absorb2

     join_absorp1            ~> sup_absorb1

     meet_absorp1            ~> inf_absorb1

     meet_absorp2            ~> inf_absorb2

     meet_join_absorp        ~> inf_sup_absorb

     join_meet_absorp        ~> sup_inf_absorb

     distrib_join_le         ~> distrib_sup_le

     distrib_meet_le         ~> distrib_inf_le

     add_meet_distrib_left   ~> add_inf_distrib_left

     add_join_distrib_left   ~> add_sup_distrib_left

     is_join_neg_meet        ~> is_join_neg_inf

     is_meet_neg_join        ~> is_meet_neg_sup

     add_meet_distrib_right  ~> add_inf_distrib_right

     add_join_distrib_right  ~> add_sup_distrib_right

     add_meet_join_distribs  ~> add_sup_inf_distribs

     join_eq_neg_meet        ~> sup_eq_neg_inf

     meet_eq_neg_join        ~> inf_eq_neg_sup

     add_eq_meet_join        ~> add_eq_inf_sup

     meet_0_imp_0            ~> inf_0_imp_0

     join_0_imp_0            ~> sup_0_imp_0

     meet_0_eq_0             ~> inf_0_eq_0

     join_0_eq_0             ~> sup_0_eq_0

     neg_meet_eq_join        ~> neg_inf_eq_sup

     neg_join_eq_meet        ~> neg_sup_eq_inf

     join_eq_if              ~> sup_eq_if

     mono_meet               ~> mono_inf

     mono_join               ~> mono_sup

     meet_bool_eq            ~> inf_bool_eq

     join_bool_eq            ~> sup_bool_eq

     meet_fun_eq             ~> inf_fun_eq

     join_fun_eq             ~> sup_fun_eq

     meet_set_eq             ~> inf_set_eq

     join_set_eq             ~> sup_set_eq

     meet1_iff               ~> inf1_iff

     meet2_iff               ~> inf2_iff

     meet1I                  ~> inf1I

     meet2I                  ~> inf2I

     meet1D1                 ~> inf1D1

     meet2D1                 ~> inf2D1

     meet1D2                 ~> inf1D2

     meet2D2                 ~> inf2D2

     meet1E                  ~> inf1E

     meet2E                  ~> inf2E

     join1_iff               ~> sup1_iff

     join2_iff               ~> sup2_iff

     join1I1                 ~> sup1I1

     join2I1                 ~> sup2I1

     join1I1                 ~> sup1I1

     join2I2                 ~> sup1I2

     join1CI                 ~> sup1CI

     join2CI                 ~> sup2CI

     join1E                  ~> sup1E

     join2E                  ~> sup2E

     is_meet_Meet            ~> is_meet_Inf

     Meet_bool_def           ~> Inf_bool_def

     Meet_fun_def            ~> Inf_fun_def

     Meet_greatest           ~> Inf_greatest

     Meet_lower              ~> Inf_lower

     Meet_set_def            ~> Inf_set_def

     Sup_def                 ~> Sup_Inf

     Sup_bool_eq             ~> Sup_bool_def

     Sup_fun_eq              ~> Sup_fun_def

     Sup_set_eq              ~> Sup_set_def

     listsp_meetI            ~> listsp_infI

     listsp_meet_eq          ~> listsp_inf_eq

     meet_min                ~> inf_min

     join_max                ~> sup_max

 * Added syntactic class "size"; overloaded constant "size" now has

 type "'a::size ==> bool"

 * Internal reorganisation of `size' of datatypes: size theorems

 "foo.size" are no longer subsumed by "foo.simps" (but are still

 simplification rules by default!); theorems "prod.size" now named

 "*.size".

 * Class "div" now inherits from class "times" rather than "type".

 INCOMPATIBILITY.

 * HOL/Finite_Set: "name-space" locales Lattice, Distrib_lattice,

 Linorder etc.  have disappeared; operations defined in terms of

 fold_set now are named Inf_fin, Sup_fin.  INCOMPATIBILITY.

 * HOL/Nat: neq0_conv no longer declared as iff.  INCOMPATIBILITY.

 * HOL-Word: New extensive library and type for generic, fixed size

 machine words, with arithemtic, bit-wise, shifting and rotating

 operations, reflection into int, nat, and bool lists, automation for

 linear arithmetic (by automatic reflection into nat or int), including

 lemmas on overflow and monotonicity.  Instantiated to all appropriate

 arithmetic type classes, supporting automatic simplification of

 numerals on all operations.

 * Library/Boolean_Algebra: locales for abstract boolean algebras.

 * Library/Numeral_Type: numbers as types, e.g. TYPE(32).

 * Code generator library theories:

   - Code_Integer represents HOL integers by big integer literals in target

     languages.

   - Code_Char represents HOL characters by character literals in target

     languages.

   - Code_Char_chr like Code_Char, but also offers treatment of character

     codes; includes Code_Integer.

   - Executable_Set allows to generate code for finite sets using lists.

   - Executable_Rat implements rational numbers as triples (sign, enumerator,

     denominator).

   - Executable_Real implements a subset of real numbers, namly those

     representable by rational numbers.

   - Efficient_Nat implements natural numbers by integers, which in general will

     result in higher efficency; pattern matching with 0/Suc is eliminated;

     includes Code_Integer.

   - Code_Index provides an additional datatype index which is mapped to

     target-language built-in integers.

   - Code_Message provides an additional datatype message_string which is isomorphic to

     strings; messages are mapped to target-language strings.

 * New package for inductive predicates

   An n-ary predicate p with m parameters z_1, ..., z_m can now be defined via

     inductive

       p :: "U_1 => ... => U_m => T_1 => ... => T_n => bool"

       for z_1 :: U_1 and ... and z_n :: U_m

     where

       rule_1: "... ==> p z_1 ... z_m t_1_1 ... t_1_n"

     | ...

   with full support for type-inference, rather than

     consts s :: "U_1 => ... => U_m => (T_1 * ... * T_n) set"

     abbreviation p :: "U_1 => ... => U_m => T_1 => ... => T_n => bool"

     where "p z_1 ... z_m x_1 ... x_n == (x_1, ..., x_n) : s z_1 ... z_m"

     inductive "s z_1 ... z_m"

     intros

       rule_1: "... ==> (t_1_1, ..., t_1_n) : s z_1 ... z_m"

       ...

   For backward compatibility, there is a wrapper allowing inductive

   sets to be defined with the new package via

     inductive_set

       s :: "U_1 => ... => U_m => (T_1 * ... * T_n) set"

       for z_1 :: U_1 and ... and z_n :: U_m

     where

       rule_1: "... ==> (t_1_1, ..., t_1_n) : s z_1 ... z_m"

     | ...

   or

     inductive_set

       s :: "U_1 => ... => U_m => (T_1 * ... * T_n) set"

       and p :: "U_1 => ... => U_m => T_1 => ... => T_n => bool"

       for z_1 :: U_1 and ... and z_n :: U_m

     where

       "p z_1 ... z_m x_1 ... x_n == (x_1, ..., x_n) : s z_1 ... z_m"

     | rule_1: "... ==> p z_1 ... z_m t_1_1 ... t_1_n"

     | ...

   if the additional syntax "p ..." is required.

   Numerous examples can be found in the subdirectories src/HOL/Auth,

   src/HOL/Bali, src/HOL/Induct, and src/HOL/MicroJava.

   INCOMPATIBILITIES:

   - Since declaration and definition of inductive sets or predicates

     is no longer separated, abbreviations involving the newly

     introduced sets or predicates must be specified together with the

     introduction rules after the 'where' keyword (see above), rather

     than before the actual inductive definition.

   - The variables in induction and elimination rules are now

     quantified in the order of their occurrence in the introduction

     rules, rather than in alphabetical order. Since this may break

     some proofs, these proofs either have to be repaired, e.g. by

     reordering the variables a_i_1 ... a_i_{k_i} in Isar 'case'

     statements of the form

       case (rule_i a_i_1 ... a_i_{k_i})

     or the old order of quantification has to be restored by explicitly adding

     meta-level quantifiers in the introduction rules, i.e.

       | rule_i: "!!a_i_1 ... a_i_{k_i}. ... ==> p z_1 ... z_m t_i_1 ... t_i_n"

   - The format of the elimination rules is now

       p z_1 ... z_m x_1 ... x_n ==>

         (!!a_1_1 ... a_1_{k_1}. x_1 = t_1_1 ==> ... ==> x_n = t_1_n ==> ... ==> P)

         ==> ... ==> P

     for predicates and

       (x_1, ..., x_n) : s z_1 ... z_m ==>

         (!!a_1_1 ... a_1_{k_1}. x_1 = t_1_1 ==> ... ==> x_n = t_1_n ==> ... ==> P)

         ==> ... ==> P

     for sets rather than

       x : s z_1 ... z_m ==>

         (!!a_1_1 ... a_1_{k_1}. x = (t_1_1, ..., t_1_n) ==> ... ==> P)

         ==> ... ==> P

     This may require terms in goals to be expanded to n-tuples

     (e.g. using case_tac or simplification with the split_paired_all

     rule) before the above elimination rule is applicable.

   - The elimination or case analysis rules for (mutually) inductive

     sets or predicates are now called "p_1.cases" ... "p_k.cases". The

     list of rules "p_1_..._p_k.elims" is no longer available.

 * New package "function"/"fun" for general recursive functions,

 supporting mutual and nested recursion, definitions in local contexts,

 more general pattern matching and partiality. See HOL/ex/Fundefs.thy

 for small examples, and the separate tutorial on the function

 package. The old recdef "package" is still available as before, but

 users are encouraged to use the new package.

 * Method "lexicographic_order" automatically synthesizes termination

 relations as lexicographic combinations of size measures. 

 * Case-expressions allow arbitrary constructor-patterns (including

 "_") and take their order into account, like in functional

 programming.  Internally, this is translated into nested

 case-expressions; missing cases are added and mapped to the predefined

 constant "undefined". In complicated cases printing may no longer show

 the original input but the internal form. Lambda-abstractions allow

 the same form of pattern matching: "% pat1 => e1 | ..." is an

 abbreviation for "%x. case x of pat1 => e1 | ..." where x is a new

 variable.

 * IntDef: The constant "int :: nat => int" has been removed; now "int"

 is an abbreviation for "of_nat :: nat => int". The simplification

 rules for "of_nat" have been changed to work like "int" did

 previously.  Potential INCOMPATIBILITY:

   - "of_nat (Suc m)" simplifies to "1 + of_nat m" instead of "of_nat m + 1"

   - of_nat_diff and of_nat_mult are no longer default simp rules

 * Method "algebra" solves polynomial equations over (semi)rings using

 Groebner bases. The (semi)ring structure is defined by locales and the

 tool setup depends on that generic context. Installing the method for

 a specific type involves instantiating the locale and possibly adding

 declarations for computation on the coefficients.  The method is

 already instantiated for natural numbers and for the axiomatic class

 of idoms with numerals.  See also the paper by Chaieb and Wenzel at

 CALCULEMUS 2007 for the general principles underlying this

 architecture of context-aware proof-tools.

 * Method "ferrack" implements quantifier elimination over

 special-purpose dense linear orders using locales (analogous to

 "algebra"). The method is already installed for class

 {ordered_field,recpower,number_ring} which subsumes real, hyperreal,

 rat, etc.

 * Former constant "List.op @" now named "List.append".  Use ML

 antiquotations @{const_name List.append} or @{term " ... @ ... "} to

 circumvent possible incompatibilities when working on ML level.

 * primrec: missing cases mapped to "undefined" instead of "arbitrary".

 * New function listsum :: 'a list => 'a for arbitrary monoids.

 Special syntax: "SUM x <- xs. f x" (and latex variants)

 * New syntax for Haskell-like list comprehension (input only), eg.

 [(x,y). x <- xs, y <- ys, x ~= y], see also src/HOL/List.thy.

 * The special syntax for function "filter" has changed from [x :

 xs. P] to [x <- xs. P] to avoid an ambiguity caused by list

 comprehension syntax, and for uniformity.  INCOMPATIBILITY.

 * [a..b] is now defined for arbitrary linear orders.  It used to be

 defined on nat only, as an abbreviation for [a..<Suc b]

 INCOMPATIBILITY.

 * Renamed lemma "set_take_whileD"  to "set_takeWhileD".

 * New functions "sorted" and "sort" in src/HOL/List.thy.

 * New lemma collection field_simps (an extension of ring_simps) for

 manipulating (in)equations involving division. Multiplies with all

 denominators that can be proved to be non-zero (in equations) or

 positive/negative (in inequations).

 * Lemma collections ring_eq_simps, group_eq_simps and ring_distrib

 have been improved and renamed to ring_simps, group_simps and

 ring_distribs.  Removed lemmas field_xyz in theory Ring_and_Field

 because they were subsumed by lemmas xyz.  INCOMPATIBILITY.

 * Theory Library/Commutative_Ring: switched from recdef to function

 package; constants add, mul, pow now curried.  Infix syntax for

 algebraic operations.

 * Dropped redundant lemma def_imp_eq in favor of meta_eq_to_obj_eq.

 INCOMPATIBILITY.

 * Dropped redundant lemma if_def2 in favor of if_bool_eq_conj.

 INCOMPATIBILITY.

 * HOL/records: generalised field-update to take a function on the

 field rather than the new value: r(|A := x|) is translated to A_update

 (K x) r The K-combinator that is internally used is called K_record.

 INCOMPATIBILITY: Usage of the plain update functions has to be

 adapted.

 * Class "semiring_0" now contains annihilation axioms x * 0 = 0 and 0

 * x = 0, which are required for a semiring.  Richer structures do not

 inherit from semiring_0 anymore, because this property is a theorem

 there, not an axiom.  INCOMPATIBILITY: In instances of semiring_0,

 there is more to prove, but this is mostly trivial.

 * Class "recpower" is generalized to arbitrary monoids, not just

 commutative semirings.  INCOMPATIBILITY: may need to incorporate

 commutativity or semiring properties additionally.

 * Constant "List.list_all2" in List.thy now uses authentic syntax.

 INCOMPATIBILITY: translations containing list_all2 may go wrong,

 better use 'abbreviation'.

 * Renamed constant "List.op mem" to "List.member".  INCOMPATIBILITY.

 * Numeral syntax: type 'bin' which was a mere type copy of 'int' has

 been abandoned in favour of plain 'int'.  INCOMPATIBILITY --

 significant changes for setting up numeral syntax for types:

   - New constants Numeral.pred and Numeral.succ instead

       of former Numeral.bin_pred and Numeral.bin_succ.

   - Use integer operations instead of bin_add, bin_mult and so on.

   - Numeral simplification theorems named Numeral.numeral_simps instead of Bin_simps.

   - ML structure Bin_Simprocs now named Int_Numeral_Base_Simprocs.

 See src/HOL/Integ/IntArith.thy for an example setup.

 * Command 'normal_form' computes the normal form of a term that may

 contain free variables.  For example ``normal_form "rev [a, b, c]"''

 produces ``[b, c, a]'' (without proof).  This command is suitable for

 heavy-duty computations because the functions are compiled to ML

 first.  Correspondingly, a method "normalization" is provided.  See

 further src/HOL/ex/NormalForm.thy and src/Tools/nbe.ML.

 * Alternative iff syntax "A <-> B" for equality on bool (with priority

 25 like -->); output depends on the "iff" print_mode, the default is

 "A = B" (with priority 50).

 * Relations less (<) and less_eq (<=) are also available on type bool.

 Modified syntax to disallow nesting without explicit parentheses,

 e.g. "(x < y) < z" or "x < (y < z)", but NOT "x < y < z".  Potential

 INCOMPATIBILITY.

 * "LEAST x:A. P" expands to "LEAST x. x:A & P" (input only).

 * Relation composition operator "op O" now has precedence 75 and binds

 stronger than union and intersection. INCOMPATIBILITY.

 * The old set interval syntax "{m..n(}" (and relatives) has been

 removed.  Use "{m..<n}" (and relatives) instead.

 * In the context of the assumption "~(s = t)" the Simplifier rewrites

 "t = s" to False (by simproc "neq").  INCOMPATIBILITY, consider using

 ``declare [[simproc del: neq]]''.

 * Simplifier: "m dvd n" where m and n are numbers is evaluated to

 True/False.

 * Theorem Cons_eq_map_conv no longer declared as "simp".

 * Theorem setsum_mult renamed to setsum_right_distrib.

 * Prefer ex1I over ex_ex1I in single-step reasoning, e.g. by the

 ``rule'' method.

 * Reimplemented methods "sat" and "satx", with several improvements:

 goals no longer need to be stated as "<prems> ==> False", equivalences

 (i.e. "=" on type bool) are handled, variable names of the form

 "lit_<n>" are no longer reserved, significant speedup.

 * Methods "sat" and "satx" can now replay MiniSat proof traces.

 zChaff is still supported as well.

 * 'inductive' and 'datatype': provide projections of mutual rules,

 bundled as foo_bar.inducts;

 * Library: moved theories Parity, GCD, Binomial, Infinite_Set to

 Library.

 * Library: moved theory Accessible_Part to main HOL.

 * Library: added theory Coinductive_List of potentially infinite lists

 as greatest fixed-point.

 * Library: added theory AssocList which implements (finite) maps as

 association lists.

 * Method "evaluation" solves goals (i.e. a boolean expression)

 efficiently by compiling it to ML.  The goal is "proved" (via an

 oracle) if it evaluates to True.

 * Linear arithmetic now splits certain operators (e.g. min, max, abs)

 also when invoked by the simplifier.  This results in the Simplifier

 being more powerful on arithmetic goals.  INCOMPATIBILITY.

 Configuration option fast_arith_split_limit=0 recovers the old

 behavior.

 * Support for hex (0x20) and binary (0b1001) numerals.

 * New method: reify eqs (t), where eqs are equations for an

 interpretation I :: 'a list => 'b => 'c and t::'c is an optional

 parameter, computes a term s::'b and a list xs::'a list and proves the

 theorem I xs s = t. This is also known as reification or quoting. The

 resulting theorem is applied to the subgoal to substitute t with I xs

 s.  If t is omitted, the subgoal itself is reified.

 * New method: reflection corr_thm eqs (t). The parameters eqs and (t)

 are as explained above. corr_thm is a theorem for I vs (f t) = I vs t,

 where f is supposed to be a computable function (in the sense of code

 generattion). The method uses reify to compute s and xs as above then

 applies corr_thm and uses normalization by evaluation to "prove" f s =

 r and finally gets the theorem t = r, which is again applied to the

 subgoal. An Example is available in src/HOL/ex/ReflectionEx.thy.

 * Reflection: Automatic reification now handels binding, an example is

 available in src/HOL/ex/ReflectionEx.thy

 * HOL-Statespace: ``State Spaces: The Locale Way'' introduces a

 command 'statespace' that is similar to 'record', but introduces an

 abstract specification based on the locale infrastructure instead of

 HOL types.  This leads to extra flexibility in composing state spaces,

 in particular multiple inheritance and renaming of components.

 *** HOL-Complex ***

 * Hyperreal: Functions root and sqrt are now defined on negative real

 inputs so that root n (- x) = - root n x and sqrt (- x) = - sqrt x.

 Nonnegativity side conditions have been removed from many lemmas, so

 that more subgoals may now be solved by simplification; potential

 INCOMPATIBILITY.

 * Real: new type classes formalize real normed vector spaces and

 algebras, using new overloaded constants scaleR :: real => 'a => 'a

 and norm :: 'a => real.

 * Real: constant of_real :: real => 'a::real_algebra_1 injects from

 reals into other types. The overloaded constant Reals :: 'a set is now

 defined as range of_real; potential INCOMPATIBILITY.

 * Real: proper support for ML code generation, including 'quickcheck'.

 Reals are implemented as arbitrary precision rationals.

 * Hyperreal: Several constants that previously worked only for the

 reals have been generalized, so they now work over arbitrary vector

 spaces. Type annotations may need to be added in some cases; potential

 INCOMPATIBILITY.

   Infinitesimal  :: ('a::real_normed_vector) star set

   HFinite        :: ('a::real_normed_vector) star set

   HInfinite      :: ('a::real_normed_vector) star set

   approx         :: ('a::real_normed_vector) star => 'a star => bool

   monad          :: ('a::real_normed_vector) star => 'a star set

   galaxy         :: ('a::real_normed_vector) star => 'a star set

   (NS)LIMSEQ     :: [nat => 'a::real_normed_vector, 'a] => bool

   (NS)convergent :: (nat => 'a::real_normed_vector) => bool

   (NS)Bseq       :: (nat => 'a::real_normed_vector) => bool

   (NS)Cauchy     :: (nat => 'a::real_normed_vector) => bool

   (NS)LIM        :: ['a::real_normed_vector => 'b::real_normed_vector, 'a, 'b] => bool

   is(NS)Cont     :: ['a::real_normed_vector => 'b::real_normed_vector, 'a] => bool

   deriv          :: ['a::real_normed_field => 'a, 'a, 'a] => bool

   sgn            :: 'a::real_normed_vector => 'a

   exp            :: 'a::{recpower,real_normed_field,banach} => 'a

 * Complex: Some complex-specific constants are now abbreviations for

 overloaded ones: complex_of_real = of_real, cmod = norm, hcmod =

 hnorm.  Other constants have been entirely removed in favor of the

 polymorphic versions (INCOMPATIBILITY):

   approx        <-- capprox

   HFinite       <-- CFinite

   HInfinite     <-- CInfinite

   Infinitesimal <-- CInfinitesimal

   monad         <-- cmonad

   galaxy        <-- cgalaxy

   (NS)LIM       <-- (NS)CLIM, (NS)CRLIM

   is(NS)Cont    <-- is(NS)Contc, is(NS)contCR

   (ns)deriv     <-- (ns)cderiv

 *** HOL-Algebra ***

 * Formalisation of ideals and the quotient construction over rings.

 * Order and lattice theory no longer based on records.

 INCOMPATIBILITY.

 * Renamed lemmas least_carrier -> least_closed and greatest_carrier ->

 greatest_closed.  INCOMPATIBILITY.

 * Method algebra is now set up via an attribute.  For examples see

 Ring.thy.  INCOMPATIBILITY: the method is now weaker on combinations

 of algebraic structures.

 * Renamed theory CRing to Ring.

 *** HOL-Nominal ***

 * Substantial, yet incomplete support for nominal datatypes (binding

 structures) based on HOL-Nominal logic.  See src/HOL/Nominal and

 src/HOL/Nominal/Examples.  Prospective users should consult

 http://isabelle.in.tum.de/nominal/

 *** ML ***

 * ML basics: just one true type int, which coincides with IntInf.int

 (even on SML/NJ).

 * ML within Isar: antiquotations allow to embed statically-checked

 formal entities in the source, referring to the context available at

 compile-time.  For example:

 ML {* @{sort "{zero,one}"} *}

 ML {* @{typ "'a => 'b"} *}

 ML {* @{term "%x. x"} *}

 ML {* @{prop "x == y"} *}

 ML {* @{ctyp "'a => 'b"} *}

 ML {* @{cterm "%x. x"} *}

 ML {* @{cprop "x == y"} *}

 ML {* @{thm asm_rl} *}

 ML {* @{thms asm_rl} *}

 ML {* @{type_name c} *}

 ML {* @{type_syntax c} *}

 ML {* @{const_name c} *}

 ML {* @{const_syntax c} *}

 ML {* @{context} *}

 ML {* @{theory} *}

 ML {* @{theory Pure} *}

 ML {* @{theory_ref} *}

 ML {* @{theory_ref Pure} *}

 ML {* @{simpset} *}

 ML {* @{claset} *}

 ML {* @{clasimpset} *}

 The same works for sources being ``used'' within an Isar context.

 * ML in Isar: improved error reporting; extra verbosity with

 ML_Context.trace enabled.

 * Pure/General/table.ML: the join operations now works via exceptions

 DUP/SAME instead of type option. This is simpler in simple cases, and

 admits slightly more efficient complex applications.

 * Pure: 'advanced' translation functions (parse_translation etc.) now

 use Context.generic instead of just theory.

 * Pure: datatype Context.generic joins theory/Proof.context and

 provides some facilities for code that works in either kind of

 context, notably GenericDataFun for uniform theory and proof data.

 * Pure: simplified internal attribute type, which is now always

 Context.generic * thm -> Context.generic * thm. Global (theory) vs.

 local (Proof.context) attributes have been discontinued, while

 minimizing code duplication. Thm.rule_attribute and

 Thm.declaration_attribute build canonical attributes; see also structure

 Context for further operations on Context.generic, notably

 GenericDataFun. INCOMPATIBILITY, need to adapt attribute type

 declarations and definitions.

 * Context data interfaces (Theory/Proof/GenericDataFun): removed

 name/print, uninitialized data defaults to ad-hoc copy of empty value,

 init only required for impure data. INCOMPATIBILITY: empty really need

 to be empty (no dependencies on theory content!)

 * Pure/kernel: consts certification ignores sort constraints given in

 signature declarations. (This information is not relevant to the

 logic, but only for type inference.) SIGNIFICANT INTERNAL CHANGE,

 potential INCOMPATIBILITY.

 * Pure: axiomatic type classes are now purely definitional, with

 explicit proofs of class axioms and super class relations performed

 internally. See Pure/axclass.ML for the main internal interfaces --

 notably AxClass.define_class supercedes AxClass.add_axclass, and

 AxClass.axiomatize_class/classrel/arity supersede

 Sign.add_classes/classrel/arities.

 * Pure/Isar: Args/Attrib parsers operate on Context.generic --

 global/local versions on theory vs. Proof.context have been

 discontinued; Attrib.syntax and Method.syntax have been adapted

 accordingly.  INCOMPATIBILITY, need to adapt parser expressions for

 attributes, methods, etc.

 * Pure: several functions of signature "... -> theory -> theory * ..."

 have been reoriented to "... -> theory -> ... * theory" in order to

 allow natural usage in combination with the ||>, ||>>, |-> and

 fold_map combinators.

 * Pure: official theorem names (closed derivations) and additional

 comments (tags) are now strictly separate.  Name hints -- which are

 maintained as tags -- may be attached any time without affecting the

 derivation.

 * Pure: primitive rule lift_rule now takes goal cterm instead of an

 actual goal state (thm).  Use Thm.lift_rule (Thm.cprem_of st i) to

 achieve the old behaviour.

 * Pure: the "Goal" constant is now called "prop", supporting a

 slightly more general idea of ``protecting'' meta-level rule

 statements.

 * Pure: Logic.(un)varify only works in a global context, which is now

 enforced instead of silently assumed.  INCOMPATIBILITY, may use

 Logic.legacy_(un)varify as temporary workaround.

 * Pure: structure Name provides scalable operations for generating

 internal variable names, notably Name.variants etc.  This replaces

 some popular functions from term.ML:

   Term.variant		->  Name.variant

   Term.variantlist	->  Name.variant_list

   Term.invent_names	->  Name.invent_list

 Note that low-level renaming rarely occurs in new code -- operations

 from structure Variable are used instead (see below).

 * Pure: structure Variable provides fundamental operations for proper

 treatment of fixed/schematic variables in a context.  For example,

 Variable.import introduces fixes for schematics of given facts and

 Variable.export reverses the effect (up to renaming) -- this replaces

 various freeze_thaw operations.

 * Pure: structure Goal provides simple interfaces for

 init/conclude/finish and tactical prove operations (replacing former

 Tactic.prove).  Goal.prove is the canonical way to prove results

 within a given context; Goal.prove_global is a degraded version for

 theory level goals, including a global Drule.standard.  Note that

 OldGoals.prove_goalw_cterm has long been obsolete, since it is

 ill-behaved in a local proof context (e.g. with local fixes/assumes or

 in a locale context).

 * Pure/Syntax: generic interfaces for parsing (Syntax.parse_term etc.)

 and type checking (Syntax.check_term etc.), with common combinations

 (Syntax.read_term etc.). These supersede former Sign.read_term etc.

 which are considered legacy and await removal.

 * Pure/Syntax: generic interfaces for type unchecking

 (Syntax.uncheck_terms etc.) and unparsing (Syntax.unparse_term etc.),

 with common combinations (Syntax.pretty_term, Syntax.string_of_term

 etc.).  Former Sign.pretty_term, Sign.string_of_term etc. are still

 available for convenience, but refer to the very same operations using

 a mere theory instead of a full context.

 * Isar: simplified treatment of user-level errors, using exception

 ERROR of string uniformly.  Function error now merely raises ERROR,

 without any side effect on output channels.  The Isar toplevel takes

 care of proper display of ERROR exceptions.  ML code may use plain

 handle/can/try; cat_error may be used to concatenate errors like this:

   ... handle ERROR msg => cat_error msg "..."

 Toplevel ML code (run directly or through the Isar toplevel) may be

 embedded into the Isar toplevel with exception display/debug like

 this:

   Isar.toplevel (fn () => ...)

 INCOMPATIBILITY, removed special transform_error facilities, removed

 obsolete variants of user-level exceptions (ERROR_MESSAGE,

 Context.PROOF, ProofContext.CONTEXT, Proof.STATE, ProofHistory.FAIL)

 -- use plain ERROR instead.

 * Isar: theory setup now has type (theory -> theory), instead of a

 list.  INCOMPATIBILITY, may use #> to compose setup functions.

 * Isar: ML toplevel pretty printer for type Proof.context, subject to

 ProofContext.debug/verbose flags.

 * Isar: Toplevel.theory_to_proof admits transactions that modify the

 theory before entering a proof state.  Transactions now always see a

 quasi-functional intermediate checkpoint, both in interactive and

 batch mode.

 * Isar: simplified interfaces for outer syntax.  Renamed

 OuterSyntax.add_keywords to OuterSyntax.keywords.  Removed

 OuterSyntax.add_parsers -- this functionality is now included in

 OuterSyntax.command etc.  INCOMPATIBILITY.

 * Simplifier: the simpset of a running simplification process now

 contains a proof context (cf. Simplifier.the_context), which is the

 very context that the initial simpset has been retrieved from (by

 simpset_of/local_simpset_of).  Consequently, all plug-in components

 (solver, looper etc.) may depend on arbitrary proof data.

 * Simplifier.inherit_context inherits the proof context (plus the

 local bounds) of the current simplification process; any simproc

 etc. that calls the Simplifier recursively should do this!  Removed

 former Simplifier.inherit_bounds, which is already included here --

 INCOMPATIBILITY.  Tools based on low-level rewriting may even have to

 specify an explicit context using Simplifier.context/theory_context.

 * Simplifier/Classical Reasoner: more abstract interfaces

 change_simpset/claset for modifying the simpset/claset reference of a

 theory; raw versions simpset/claset_ref etc. have been discontinued --

 INCOMPATIBILITY.

 * Provers: more generic wrt. syntax of object-logics, avoid hardwired

 "Trueprop" etc.

 *** System ***

 * settings: the default heap location within ISABELLE_HOME_USER now

 includes ISABELLE_IDENTIFIER.  This simplifies use of multiple

 Isabelle installations.

 * isabelle-process: option -S (secure mode) disables some critical

 operations, notably runtime compilation and evaluation of ML source

 code.

 * Basic Isabelle mode for jEdit, see Isabelle/lib/jedit/.

 * Support for parallel execution, using native multicore support of

 Poly/ML 5.1.  The theory loader exploits parallelism when processing

 independent theories, according to the given theory header

 specifications. The maximum number of worker threads is specified via

 usedir option -M or the "max-threads" setting in Proof General. A

 speedup factor of 1.5--3.5 can be expected on a 4-core machine, and up

 to 6 on a 8-core machine.  User-code needs to observe certain

 guidelines for thread-safe programming, see appendix A in the Isar

 Implementation manual.

 New in Isabelle2005 (October 2005)

 ----------------------------------

 *** General ***

 * Theory headers: the new header syntax for Isar theories is

   theory <name>

   imports <theory1> ... <theoryN>

   uses <file1> ... <fileM>

   begin

 where the 'uses' part is optional.  The previous syntax

   theory <name> = <theory1> + ... + <theoryN>:

 will disappear in the next release.  Use isatool fixheaders to convert

 existing theory files.  Note that there is no change in ancient

 non-Isar theories now, but these will disappear soon.

 * Theory loader: parent theories can now also be referred to via

 relative and absolute paths.

 * Command 'find_theorems' searches for a list of criteria instead of a

 list of constants. Known criteria are: intro, elim, dest, name:string,

 simp:term, and any term. Criteria can be preceded by '-' to select

 theorems that do not match. Intro, elim, dest select theorems that

 match the current goal, name:s selects theorems whose fully qualified

 name contain s, and simp:term selects all simplification rules whose

 lhs match term.  Any other term is interpreted as pattern and selects

 all theorems matching the pattern. Available in ProofGeneral under

 'ProofGeneral -> Find Theorems' or C-c C-f.  Example:

   C-c C-f (100) "(_::nat) + _ + _" intro -name: "HOL."

 prints the last 100 theorems matching the pattern "(_::nat) + _ + _",

 matching the current goal as introduction rule and not having "HOL."

 in their name (i.e. not being defined in theory HOL).

 * Command 'thms_containing' has been discontinued in favour of

 'find_theorems'; INCOMPATIBILITY.

 * Communication with Proof General is now 8bit clean, which means that

 Unicode text in UTF-8 encoding may be used within theory texts (both

 formal and informal parts).  Cf. option -U of the Isabelle Proof

 General interface.  Here are some simple examples (cf. src/HOL/ex):

   http://isabelle.in.tum.de/library/HOL/ex/Hebrew.html

   http://isabelle.in.tum.de/library/HOL/ex/Chinese.html

 * Improved efficiency of the Simplifier and, to a lesser degree, the

 Classical Reasoner.  Typical big applications run around 2 times

 faster.

 *** Document preparation ***

 * Commands 'display_drafts' and 'print_drafts' perform simple output

 of raw sources.  Only those symbols that do not require additional

 LaTeX packages (depending on comments in isabellesym.sty) are

 displayed properly, everything else is left verbatim.  isatool display

 and isatool print are used as front ends (these are subject to the

 DVI/PDF_VIEWER and PRINT_COMMAND settings, respectively).

 * Command tags control specific markup of certain regions of text,

 notably folding and hiding.  Predefined tags include "theory" (for

 theory begin and end), "proof" for proof commands, and "ML" for

 commands involving ML code; the additional tags "visible" and

 "invisible" are unused by default.  Users may give explicit tag

 specifications in the text, e.g. ''by %invisible (auto)''.  The

 interpretation of tags is determined by the LaTeX job during document

 preparation: see option -V of isatool usedir, or options -n and -t of

 isatool document, or even the LaTeX macros \isakeeptag, \isafoldtag,

 \isadroptag.

 Several document versions may be produced at the same time via isatool

 usedir (the generated index.html will link all of them).  Typical

 specifications include ''-V document=theory,proof,ML'' to present

 theory/proof/ML parts faithfully, ''-V outline=/proof,/ML'' to fold

 proof and ML commands, and ''-V mutilated=-theory,-proof,-ML'' to omit

 these parts without any formal replacement text.  The Isabelle site

 default settings produce ''document'' and ''outline'' versions as

 specified above.

 * Several new antiquotations:

   @{term_type term} prints a term with its type annotated;

   @{typeof term} prints the type of a term;

   @{const const} is the same as @{term const}, but checks that the

   argument is a known logical constant;

   @{term_style style term} and @{thm_style style thm} print a term or

   theorem applying a "style" to it

   @{ML text}

 Predefined styles are 'lhs' and 'rhs' printing the lhs/rhs of

 definitions, equations, inequations etc., 'concl' printing only the

 conclusion of a meta-logical statement theorem, and 'prem1' .. 'prem19'

 to print the specified premise.  TermStyle.add_style provides an ML

 interface for introducing further styles.  See also the "LaTeX Sugar"

 document practical applications.  The ML antiquotation prints

 type-checked ML expressions verbatim.

 * Markup commands 'chapter', 'section', 'subsection', 'subsubsection',

 and 'text' support optional locale specification '(in loc)', which

 specifies the default context for interpreting antiquotations.  For

 example: 'text (in lattice) {* @{thm inf_assoc}*}'.

 * Option 'locale=NAME' of antiquotations specifies an alternative

 context interpreting the subsequent argument.  For example: @{thm

 [locale=lattice] inf_assoc}.

 * Proper output of proof terms (@{prf ...} and @{full_prf ...}) within

 a proof context.

 * Proper output of antiquotations for theory commands involving a

 proof context (such as 'locale' or 'theorem (in loc) ...').

 * Delimiters of outer tokens (string etc.) now produce separate LaTeX

 macros (\isachardoublequoteopen, isachardoublequoteclose etc.).

 * isatool usedir: new option -C (default true) controls whether option

 -D should include a copy of the original document directory; -C false

 prevents unwanted effects such as copying of administrative CVS data.

 *** Pure ***

 * Considerably improved version of 'constdefs' command.  Now performs

 automatic type-inference of declared constants; additional support for

 local structure declarations (cf. locales and HOL records), see also

 isar-ref manual.  Potential INCOMPATIBILITY: need to observe strictly

 sequential dependencies of definitions within a single 'constdefs'

 section; moreover, the declared name needs to be an identifier.  If

 all fails, consider to fall back on 'consts' and 'defs' separately.

 * Improved indexed syntax and implicit structures.  First of all,

 indexed syntax provides a notational device for subscripted

 application, using the new syntax \<^bsub>term\<^esub> for arbitrary

 expressions.  Secondly, in a local context with structure

 declarations, number indexes \<^sub>n or the empty index (default

 number 1) refer to a certain fixed variable implicitly; option

 show_structs controls printing of implicit structures.  Typical

 applications of these concepts involve record types and locales.

 * New command 'no_syntax' removes grammar declarations (and

 translations) resulting from the given syntax specification, which is

 interpreted in the same manner as for the 'syntax' command.

 * 'Advanced' translation functions (parse_translation etc.) may depend

 on the signature of the theory context being presently used for

 parsing/printing, see also isar-ref manual.

 * Improved 'oracle' command provides a type-safe interface to turn an

 ML expression of type theory -> T -> term into a primitive rule of

 type theory -> T -> thm (i.e. the functionality of Thm.invoke_oracle

 is already included here); see also FOL/ex/IffExample.thy;

 INCOMPATIBILITY.

 * axclass: name space prefix for class "c" is now "c_class" (was "c"

 before); "cI" is no longer bound, use "c.intro" instead.

 INCOMPATIBILITY.  This change avoids clashes of fact bindings for

 axclasses vs. locales.

 * Improved internal renaming of symbolic identifiers -- attach primes

 instead of base 26 numbers.

 * New flag show_question_marks controls printing of leading question

 marks in schematic variable names.

 * In schematic variable names, *any* symbol following \<^isub> or

 \<^isup> is now treated as part of the base name.  For example, the

 following works without printing of awkward ".0" indexes:

   lemma "x\<^isub>1 = x\<^isub>2 ==> x\<^isub>2 = x\<^isub>1"

     by simp

 * Inner syntax includes (*(*nested*) comments*).

 * Pretty printer now supports unbreakable blocks, specified in mixfix

 annotations as "(00...)".

 * Clear separation of logical types and nonterminals, where the latter

 may only occur in 'syntax' specifications or type abbreviations.

 Before that distinction was only partially implemented via type class

 "logic" vs. "{}".  Potential INCOMPATIBILITY in rare cases of improper

 use of 'types'/'consts' instead of 'nonterminals'/'syntax'.  Some very

 exotic syntax specifications may require further adaption

 (e.g. Cube/Cube.thy).

 * Removed obsolete type class "logic", use the top sort {} instead.

 Note that non-logical types should be declared as 'nonterminals'

 rather than 'types'.  INCOMPATIBILITY for new object-logic

 specifications.

 * Attributes 'induct' and 'cases': type or set names may now be

 locally fixed variables as well.

 * Simplifier: can now control the depth to which conditional rewriting

 is traced via the PG menu Isabelle -> Settings -> Trace Simp Depth

 Limit.

 * Simplifier: simplification procedures may now take the current

 simpset into account (cf. Simplifier.simproc(_i) / mk_simproc

 interface), which is very useful for calling the Simplifier

 recursively.  Minor INCOMPATIBILITY: the 'prems' argument of simprocs

 is gone -- use prems_of_ss on the simpset instead.  Moreover, the

 low-level mk_simproc no longer applies Logic.varify internally, to

 allow for use in a context of fixed variables.

 * thin_tac now works even if the assumption being deleted contains !!

 or ==>.  More generally, erule now works even if the major premise of

 the elimination rule contains !! or ==>.

 * Method 'rules' has been renamed to 'iprover'. INCOMPATIBILITY.

 * Reorganized bootstrapping of the Pure theories; CPure is now derived

 from Pure, which contains all common declarations already.  Both

 theories are defined via plain Isabelle/Isar .thy files.

 INCOMPATIBILITY: elements of CPure (such as the CPure.intro /

 CPure.elim / CPure.dest attributes) now appear in the Pure name space;

 use isatool fixcpure to adapt your theory and ML sources.

 * New syntax 'name(i-j, i-, i, ...)' for referring to specific

 selections of theorems in named facts via index ranges.

 * 'print_theorems': in theory mode, really print the difference

 wrt. the last state (works for interactive theory development only),

 in proof mode print all local facts (cf. 'print_facts');

 * 'hide': option '(open)' hides only base names.

 * More efficient treatment of intermediate checkpoints in interactive

 theory development.

 * Code generator is now invoked via code_module (incremental code

 generation) and code_library (modular code generation, ML structures

 for each theory).  INCOMPATIBILITY: new keywords 'file' and 'contains'

 must be quoted when used as identifiers.

 * New 'value' command for reading, evaluating and printing terms using

 the code generator.  INCOMPATIBILITY: command keyword 'value' must be

 quoted when used as identifier.

 *** Locales ***

 * New commands for the interpretation of locale expressions in

 theories (1), locales (2) and proof contexts (3).  These generate

 proof obligations from the expression specification.  After the

 obligations have been discharged, theorems of the expression are added

 to the theory, target locale or proof context.  The synopsis of the

 commands is a follows:

   (1) interpretation expr inst

   (2) interpretation target < expr

   (3) interpret expr inst

 Interpretation in theories and proof contexts require a parameter

 instantiation of terms from the current context.  This is applied to

 specifications and theorems of the interpreted expression.

 Interpretation in locales only permits parameter renaming through the

 locale expression.  Interpretation is smart in that interpretations

 that are active already do not occur in proof obligations, neither are

 instantiated theorems stored in duplicate.  Use 'print_interps' to

 inspect active interpretations of a particular locale.  For details,

 see the Isar Reference manual.  Examples can be found in

 HOL/Finite_Set.thy and HOL/Algebra/UnivPoly.thy.

 INCOMPATIBILITY: former 'instantiate' has been withdrawn, use

 'interpret' instead.

 * New context element 'constrains' for adding type constraints to

 parameters.

 * Context expressions: renaming of parameters with syntax

 redeclaration.

 * Locale declaration: 'includes' disallowed.

 * Proper static binding of attribute syntax -- i.e. types / terms /

 facts mentioned as arguments are always those of the locale definition

 context, independently of the context of later invocations.  Moreover,

 locale operations (renaming and type / term instantiation) are applied

 to attribute arguments as expected.

 INCOMPATIBILITY of the ML interface: always pass Attrib.src instead of

 actual attributes; rare situations may require Attrib.attribute to

 embed those attributes into Attrib.src that lack concrete syntax.

 Attribute implementations need to cooperate properly with the static

 binding mechanism.  Basic parsers Args.XXX_typ/term/prop and

 Attrib.XXX_thm etc. already do the right thing without further

 intervention.  Only unusual applications -- such as "where" or "of"

 (cf. src/Pure/Isar/attrib.ML), which process arguments depending both

 on the context and the facts involved -- may have to assign parsed

 values to argument tokens explicitly.

 * Changed parameter management in theorem generation for long goal

 statements with 'includes'.  INCOMPATIBILITY: produces a different

 theorem statement in rare situations.

 * Locale inspection command 'print_locale' omits notes elements.  Use

 'print_locale!' to have them included in the output.

 *** Provers ***

 * Provers/hypsubst.ML: improved version of the subst method, for

 single-step rewriting: it now works in bound variable contexts. New is

 'subst (asm)', for rewriting an assumption.  INCOMPATIBILITY: may

 rewrite a different subterm than the original subst method, which is

 still available as 'simplesubst'.

 * Provers/quasi.ML: new transitivity reasoners for transitivity only

 and quasi orders.

 * Provers/trancl.ML: new transitivity reasoner for transitive and

 reflexive-transitive closure of relations.

 * Provers/blast.ML: new reference depth_limit to make blast's depth

 limit (previously hard-coded with a value of 20) user-definable.

 * Provers/simplifier.ML has been moved to Pure, where Simplifier.setup

 is peformed already.  Object-logics merely need to finish their

 initial simpset configuration as before.  INCOMPATIBILITY.

 *** HOL ***

 * Symbolic syntax of Hilbert Choice Operator is now as follows:

   syntax (epsilon)

     "_Eps" :: "[pttrn, bool] => 'a"    ("(3\<some>_./ _)" [0, 10] 10)

 The symbol \<some> is displayed as the alternative epsilon of LaTeX

 and x-symbol; use option '-m epsilon' to get it actually printed.

 Moreover, the mathematically important symbolic identifier \<epsilon>

 becomes available as variable, constant etc.  INCOMPATIBILITY,

 * "x > y" abbreviates "y < x" and "x >= y" abbreviates "y <= x".

 Similarly for all quantifiers: "ALL x > y" etc.  The x-symbol for >=

 is \<ge>. New transitivity rules have been added to HOL/Orderings.thy to

 support corresponding Isar calculations.

 * "{x:A. P}" abbreviates "{x. x:A & P}", and similarly for "\<in>"

 instead of ":".

 * theory SetInterval: changed the syntax for open intervals:

   Old       New

   {..n(}    {..<n}

   {)n..}    {n<..}

   {m..n(}   {m..<n}

   {)m..n}   {m<..n}

   {)m..n(}  {m<..<n}

 The old syntax is still supported but will disappear in the next

 release.  For conversion use the following Emacs search and replace

 patterns (these are not perfect but work quite well):

   {)\([^\.]*\)\.\.  ->  {\1<\.\.}

   \.\.\([^(}]*\)(}  ->  \.\.<\1}

 * Theory Commutative_Ring (in Library): method comm_ring for proving

 equalities in commutative rings; method 'algebra' provides a generic

 interface.

 * Theory Finite_Set: changed the syntax for 'setsum', summation over

 finite sets: "setsum (%x. e) A", which used to be "\<Sum>x:A. e", is

 now either "SUM x:A. e" or "\<Sum>x \<in> A. e". The bound variable can

 be a tuple pattern.

 Some new syntax forms are available:

   "\<Sum>x | P. e"      for     "setsum (%x. e) {x. P}"

   "\<Sum>x = a..b. e"   for     "setsum (%x. e) {a..b}"

   "\<Sum>x = a..<b. e"  for     "setsum (%x. e) {a..<b}"

   "\<Sum>x < k. e"      for     "setsum (%x. e) {..<k}"

 The latter form "\<Sum>x < k. e" used to be based on a separate

 function "Summation", which has been discontinued.