Isabelle NEWS -- history user-relevant changes

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

 New in Isabelle2007

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

 *** 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.

 * 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 ***

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

 referred to by usual term syntax (including optional type

 annotations).

 * Code generator: basic definitions (from 'definition', 'constdefs',

 or primitive 'instance' definitions) are added automatically to the

 table of defining equations.  Primitive defs are not used as defining

 equations by default any longer.  defining equations are now definitly

 restricted to meta "==" and object equality "=".

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

 achieve Haskell-like type classes in Isabelle.  See

 HOL/ex/Classpackage.thy for examples.

 * Yet another code generator framework allows to generate executable

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

 sketch:

     internal compilation:

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

     writing SML code to a file:

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

     writing OCaml code to a file:

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

     writing Haskell code to a bunch of files:

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

 Reasonable default setup of framework in HOL/Main.

 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 apply to target Haskell.

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

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

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

 codegen".

 * 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

 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

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

 * 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).

 * 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"

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

 for locales "order" and "linorder" generated by the new class package

 (instead of axiomatic type classes used before).  Instances of the

 reasoner are available in all contexts importing or interpreting these

 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.

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

 with new class dense_linear_order.

 * 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-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:

   - Pretty_Int represents HOL integers by big integer literals in target

     languages.

   - Pretty_Char represents HOL characters by character literals in target

     languages.

   - Pretty_Char_chr like Pretty_Char, but also offers treatment of character

     codes; includes Pretty_Int.

   - 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 Pretty_Int.

   - ML_String provides an additional datatype ml_string; in the HOL default

     setup, strings in HOL are mapped to lists of HOL characters in SML; values

     of type ml_string are mapped to strings in SML.

   - ML_Int provides an additional datatype ml_int which is mapped to to SML

     built-in integers.

 * 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 HOL/Auth, HOL/Bali,

   HOL/Induct, and 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.

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

 resolution prover.  Examples are in the directory MetisExamples.  See

 also http://gilith.com/software/metis/

 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.

 * 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.

 * 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.

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

 the new 'class' package:

     HOL.abs ~> HOL.minus_class.abs

     HOL.divide ~> HOL.divide_class.divide

     Nat.power ~> Nat.power_class.power

     Nat.size ~> Nat.size_class.size

     Numeral.number_of ~> Numeral.number_class.number_of

     FixedPoint.Inf ~> FixedPoint.complete_lattice_class.Inf

     FixedPoint.Sup ~> FixedPoint.complete_lattice_class.Sup

     Orderings.min ~> Orderings.ord_class.min

     Orderings.max ~> Orderings.ord_class.max

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

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

 * 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 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 HOL/List.thy.

 * 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.

 * 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.

 * Library/Pretty_Int.thy: maps HOL numerals on target language integer

 literals when generating code.

 * Library/Pretty_Char.thy: maps HOL characters on target language

 character literals when generating code.

 * Library/Commutative_Ring.thy: switched from recdef to function

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

 algebraic operations.

 * Some steps towards more 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

 * Renamed 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 instance proofs.

 * 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.

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

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

 * Renamed constants "Divides.op div", "Divides.op mod" and "Divides.op

 dvd" to "Divides.div_class.div", "Divides.div_class.mod" and

 "Divides.dvd". INCOMPATIBILITY.

 * Method "lexicographic_order" automatically synthesizes termination

 relations as lexicographic combinations of size measures -- 'function'

 package.

 * 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 a semiring properties additionally.

 * Unified locale "partial_order" with class definition (cf. theory

 Orderings), added parameter "less".  INCOMPATIBILITY.

 * 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.

 * Renamed constants "0" to "HOL.zero_class.zero" and "1" to

 "HOL.one_class.one".  INCOMPATIBILITY.

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

 equality.

 * 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 HOL/Integ/IntArith.thy for an example setup.

 * New top level 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.

 * 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).

 * Renamed constants in HOL.thy and Orderings.thy:

     op +   ~> HOL.plus_class.plus

     op -   ~> HOL.minus_class.minus

     uminus ~> HOL.minus_class.uminus

     abs    ~> HOL.abs_class.abs

     op *   ~> HOL.times_class.times

     op <   ~> HOL.ord_class.less

     op <=  ~> HOL.ord_class.less_eq

 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.

 * 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 HOL/ex/ReflectionEx.thy.

 * Reflection: Automatic reification now handels binding, an example

 is available in HOL/ex/ReflectionEx.thy

 *** 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 ***

 * Fully featured support for nominal datatypes (binding structures)

 due to the HOL-Nominal logic.  See HOL/Nominal, HOL/Nominal/Examples,

 and http://isabelle.in.tum.de/nominal/download.html

 *** 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 {* @{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 {* @{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: ML_IDENTIFIER -- which is appended to user specific heap

 locations -- now includes the Isabelle version identifier as well.

 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.

 * theory Finite_Set: in structured induction proofs, the insert case

 is now 'case (insert x F)' instead of the old counterintuitive 'case

 (insert F x)'.

 * The 'refute' command has been extended to support a much larger

 fragment of HOL, including axiomatic type classes, constdefs and

 typedefs, inductive datatypes and recursion.

 * New tactics 'sat' and 'satx' to prove propositional tautologies.

 Requires zChaff with proof generation to be installed.  See

 HOL/ex/SAT_Examples.thy for examples.

 * Datatype induction via method 'induct' now preserves the name of the

 induction variable. For example, when proving P(xs::'a list) by

 induction on xs, the induction step is now P(xs) ==> P(a#xs) rather

 than P(list) ==> P(a#list) as previously.  Potential INCOMPATIBILITY

 in unstructured proof scripts.

 * Reworked implementation of records.  Improved scalability for

 records with many fields, avoiding performance problems for type

 inference. Records are no longer composed of nested field types, but

 of nested extension types. Therefore the record type only grows linear

 in the number of extensions and not in the number of fields.  The

 top-level (users) view on records is preserved.  Potential

 INCOMPATIBILITY only in strange cases, where the theory depends on the

 old record representation. The type generated for a record is called

 <record_name>_ext_type.

 Flag record_quick_and_dirty_sensitive can be enabled to skip the

 proofs triggered by a record definition or a simproc (if

 quick_and_dirty is enabled).  Definitions of large records can take

 quite long.

 New simproc record_upd_simproc for simplification of multiple record

 updates enabled by default.  Moreover, trivial updates are also

 removed: r(|x := x r|) = r.  INCOMPATIBILITY: old proofs break

 occasionally, since simplification is more powerful by default.

 * typedef: proper support for polymorphic sets, which contain extra

 type-variables in the term.

 * Simplifier: automatically reasons about transitivity chains

 involving "trancl" (r^+) and "rtrancl" (r^*) by setting up tactics

 provided by Provers/trancl.ML as additional solvers.  INCOMPATIBILITY:

 old proofs break occasionally as simplification may now solve more

 goals than previously.

 * Simplifier: converts x <= y into x = y if assumption y <= x is

 present.  Works for all partial orders (class "order"), in particular

 numbers and sets.  For linear orders (e.g. numbers) it treats ~ x < y

 just like y <= x.

 * Simplifier: new simproc for "let x = a in f x".  If a is a free or

 bound variable or a constant then the let is unfolded.  Otherwise

 first a is simplified to b, and then f b is simplified to g. If

 possible we abstract b from g arriving at "let x = b in h x",

 otherwise we unfold the let and arrive at g.  The simproc can be

 enabled/disabled by the reference use_let_simproc.  Potential

 INCOMPATIBILITY since simplification is more powerful by default.

 * Classical reasoning: the meson method now accepts theorems as arguments.

 * Prover support: pre-release of the Isabelle-ATP linkup, which runs background

 jobs to provide advice on the provability of subgoals.

 * Theory OrderedGroup and Ring_and_Field: various additions and

 improvements to faciliate calculations involving equalities and

 inequalities.

 The following theorems have been eliminated or modified

 (INCOMPATIBILITY):

   abs_eq             now named abs_of_nonneg

   abs_of_ge_0        now named abs_of_nonneg

   abs_minus_eq       now named abs_of_nonpos

   imp_abs_id         now named abs_of_nonneg

   imp_abs_neg_id     now named abs_of_nonpos

   mult_pos           now named mult_pos_pos

   mult_pos_le        now named mult_nonneg_nonneg

   mult_pos_neg_le    now named mult_nonneg_nonpos

   mult_pos_neg2_le   now named mult_nonneg_nonpos2

   mult_neg           now named mult_neg_neg

   mult_neg_le        now named mult_nonpos_nonpos

 * The following lemmas in Ring_and_Field have been added to the simplifier:

      zero_le_square

      not_square_less_zero 

   The following lemmas have been deleted from Real/RealPow:

      realpow_zero_zero

      realpow_two

      realpow_less

      zero_le_power

      realpow_two_le

      abs_realpow_two

      realpow_two_abs     

 * Theory Parity: added rules for simplifying exponents.

 * Theory List:

 The following theorems have been eliminated or modified

 (INCOMPATIBILITY):

   list_all_Nil       now named list_all.simps(1)

   list_all_Cons      now named list_all.simps(2)

   list_all_conv      now named list_all_iff

   set_mem_eq         now named mem_iff

 * Theories SetsAndFunctions and BigO (see HOL/Library) support

 asymptotic "big O" calculations.  See the notes in BigO.thy.

 *** HOL-Complex ***

 * Theory RealDef: better support for embedding natural numbers and

 integers in the reals.

 The following theorems have been eliminated or modified

 (INCOMPATIBILITY):

   exp_ge_add_one_self  now requires no hypotheses

   real_of_int_add      reversed direction of equality (use [symmetric])

   real_of_int_minus    reversed direction of equality (use [symmetric])

   real_of_int_diff     reversed direction of equality (use [symmetric])

   real_of_int_mult     reversed direction of equality (use [symmetric])

 * Theory RComplete: expanded support for floor and ceiling functions.

 * Theory Ln is new, with properties of the natural logarithm

 * Hyperreal: There is a new type constructor "star" for making

 nonstandard types.  The old type names are now type synonyms:

   hypreal = real star

   hypnat = nat star

   hcomplex = complex star

 * Hyperreal: Many groups of similarly-defined constants have been

 replaced by polymorphic versions (INCOMPATIBILITY):

   star_of <-- hypreal_of_real, hypnat_of_nat, hcomplex_of_complex

   starset      <-- starsetNat, starsetC

   *s*          <-- *sNat*, *sc*

   starset_n    <-- starsetNat_n, starsetC_n

   *sn*         <-- *sNatn*, *scn*

   InternalSets <-- InternalNatSets, InternalCSets

   starfun      <-- starfun{Nat,Nat2,C,RC,CR}

   *f*          <-- *fNat*, *fNat2*, *fc*, *fRc*, *fcR*

   starfun_n    <-- starfun{Nat,Nat2,C,RC,CR}_n

   *fn*         <-- *fNatn*, *fNat2n*, *fcn*, *fRcn*, *fcRn*

   InternalFuns <-- InternalNatFuns, InternalNatFuns2, Internal{C,RC,CR}Funs

 * Hyperreal: Many type-specific theorems have been removed in favor of

 theorems specific to various axiomatic type classes (INCOMPATIBILITY):

   add_commute <-- {hypreal,hypnat,hcomplex}_add_commute

   add_assoc   <-- {hypreal,hypnat,hcomplex}_add_assocs

   OrderedGroup.add_0 <-- {hypreal,hypnat,hcomplex}_add_zero_left

   OrderedGroup.add_0_right <-- {hypreal,hcomplex}_add_zero_right

   right_minus <-- hypreal_add_minus

   left_minus <-- {hypreal,hcomplex}_add_minus_left

   mult_commute <-- {hypreal,hypnat,hcomplex}_mult_commute

   mult_assoc <-- {hypreal,hypnat,hcomplex}_mult_assoc

   mult_1_left <-- {hypreal,hypnat}_mult_1, hcomplex_mult_one_left

   mult_1_right <-- hcomplex_mult_one_right

   mult_zero_left <-- hcomplex_mult_zero_left

   left_distrib <-- {hypreal,hypnat,hcomplex}_add_mult_distrib

   right_distrib <-- hypnat_add_mult_distrib2

   zero_neq_one <-- {hypreal,hypnat,hcomplex}_zero_not_eq_one

   right_inverse <-- hypreal_mult_inverse

   left_inverse <-- hypreal_mult_inverse_left, hcomplex_mult_inv_left

   order_refl <-- {hypreal,hypnat}_le_refl

   order_trans <-- {hypreal,hypnat}_le_trans

   order_antisym <-- {hypreal,hypnat}_le_anti_sym

   order_less_le <-- {hypreal,hypnat}_less_le

   linorder_linear <-- {hypreal,hypnat}_le_linear

   add_left_mono <-- {hypreal,hypnat}_add_left_mono

   mult_strict_left_mono <-- {hypreal,hypnat}_mult_less_mono2

   add_nonneg_nonneg <-- hypreal_le_add_order

 * Hyperreal: Separate theorems having to do with type-specific

 versions of constants have been merged into theorems that apply to the

 new polymorphic constants (INCOMPATIBILITY):

   STAR_UNIV_set <-- {STAR_real,NatStar_real,STARC_complex}_set

   STAR_empty_set <-- {STAR,NatStar,STARC}_empty_set

   STAR_Un <-- {STAR,NatStar,STARC}_Un

   STAR_Int <-- {STAR,NatStar,STARC}_Int

   STAR_Compl <-- {STAR,NatStar,STARC}_Compl

   STAR_subset <-- {STAR,NatStar,STARC}_subset

   STAR_mem <-- {STAR,NatStar,STARC}_mem

   STAR_mem_Compl <-- {STAR,STARC}_mem_Compl

   STAR_diff <-- {STAR,STARC}_diff

   STAR_star_of_image_subset <-- {STAR_hypreal_of_real, NatStar_hypreal_of_real,

     STARC_hcomplex_of_complex}_image_subset

   starset_n_Un <-- starset{Nat,C}_n_Un

   starset_n_Int <-- starset{Nat,C}_n_Int

   starset_n_Compl <-- starset{Nat,C}_n_Compl

   starset_n_diff <-- starset{Nat,C}_n_diff

   InternalSets_Un <-- Internal{Nat,C}Sets_Un

   InternalSets_Int <-- Internal{Nat,C}Sets_Int

   InternalSets_Compl <-- Internal{Nat,C}Sets_Compl

   InternalSets_diff <-- Internal{Nat,C}Sets_diff

   InternalSets_UNIV_diff <-- Internal{Nat,C}Sets_UNIV_diff

   InternalSets_starset_n <-- Internal{Nat,C}Sets_starset{Nat,C}_n

   starset_starset_n_eq <-- starset{Nat,C}_starset{Nat,C}_n_eq

   starset_n_starset <-- starset{Nat,C}_n_starset{Nat,C}

   starfun_n_starfun <-- starfun{Nat,Nat2,C,RC,CR}_n_starfun{Nat,Nat2,C,RC,CR}

   starfun <-- starfun{Nat,Nat2,C,RC,CR}

   starfun_mult <-- starfun{Nat,Nat2,C,RC,CR}_mult

   starfun_add <-- starfun{Nat,Nat2,C,RC,CR}_add

   starfun_minus <-- starfun{Nat,Nat2,C,RC,CR}_minus

   starfun_diff <-- starfun{C,RC,CR}_diff

   starfun_o <-- starfun{NatNat2,Nat2,_stafunNat,C,C_starfunRC,_starfunCR}_o

   starfun_o2 <-- starfun{NatNat2,_stafunNat,C,C_starfunRC,_starfunCR}_o2

   starfun_const_fun <-- starfun{Nat,Nat2,C,RC,CR}_const_fun

   starfun_inverse <-- starfun{Nat,C,RC,CR}_inverse

   starfun_eq <-- starfun{Nat,Nat2,C,RC,CR}_eq

   starfun_eq_iff <-- starfun{C,RC,CR}_eq_iff

   starfun_Id <-- starfunC_Id

   starfun_approx <-- starfun{Nat,CR}_approx

   starfun_capprox <-- starfun{C,RC}_capprox

   starfun_abs <-- starfunNat_rabs

   starfun_lambda_cancel <-- starfun{C,CR,RC}_lambda_cancel

   starfun_lambda_cancel2 <-- starfun{C,CR,RC}_lambda_cancel2

   starfun_mult_HFinite_approx <-- starfunCR_mult_HFinite_capprox

   starfun_mult_CFinite_capprox <-- starfun{C,RC}_mult_CFinite_capprox

   starfun_add_capprox <-- starfun{C,RC}_add_capprox

   starfun_add_approx <-- starfunCR_add_approx

   starfun_inverse_inverse <-- starfunC_inverse_inverse

   starfun_divide <-- starfun{C,CR,RC}_divide

   starfun_n <-- starfun{Nat,C}_n

   starfun_n_mult <-- starfun{Nat,C}_n_mult

   starfun_n_add <-- starfun{Nat,C}_n_add

   starfun_n_add_minus <-- starfunNat_n_add_minus

   starfun_n_const_fun <-- starfun{Nat,C}_n_const_fun

   starfun_n_minus <-- starfun{Nat,C}_n_minus

   starfun_n_eq <-- starfun{Nat,C}_n_eq

   star_n_add <-- {hypreal,hypnat,hcomplex}_add

   star_n_minus <-- {hypreal,hcomplex}_minus

   star_n_diff <-- {hypreal,hcomplex}_diff

   star_n_mult <-- {hypreal,hcomplex}_mult

   star_n_inverse <-- {hypreal,hcomplex}_inverse

   star_n_le <-- {hypreal,hypnat}_le

   star_n_less <-- {hypreal,hypnat}_less

   star_n_zero_num <-- {hypreal,hypnat,hcomplex}_zero_num

   star_n_one_num <-- {hypreal,hypnat,hcomplex}_one_num

   star_n_abs <-- hypreal_hrabs

   star_n_divide <-- hcomplex_divide

   star_of_add <-- {hypreal_of_real,hypnat_of_nat,hcomplex_of_complex}_add

   star_of_minus <-- {hypreal_of_real,hcomplex_of_complex}_minus

   star_of_diff <-- hypreal_of_real_diff

   star_of_mult <-- {hypreal_of_real,hypnat_of_nat,hcomplex_of_complex}_mult

   star_of_one <-- {hypreal_of_real,hcomplex_of_complex}_one

   star_of_zero <-- {hypreal_of_real,hypnat_of_nat,hcomplex_of_complex}_zero

   star_of_le <-- {hypreal_of_real,hypnat_of_nat}_le_iff

   star_of_less <-- {hypreal_of_real,hypnat_of_nat}_less_iff

   star_of_eq <-- {hypreal_of_real,hypnat_of_nat,hcomplex_of_complex}_eq_iff

   star_of_inverse <-- {hypreal_of_real,hcomplex_of_complex}_inverse

   star_of_divide <-- {hypreal_of_real,hcomplex_of_complex}_divide

   star_of_of_nat <-- {hypreal_of_real,hcomplex_of_complex}_of_nat

   star_of_of_int <-- {hypreal_of_real,hcomplex_of_complex}_of_int

   star_of_number_of <-- {hypreal,hcomplex}_number_of

   star_of_number_less <-- number_of_less_hypreal_of_real_iff

   star_of_number_le <-- number_of_le_hypreal_of_real_iff

   star_of_eq_number <-- hypreal_of_real_eq_number_of_iff

   star_of_less_number <-- hypreal_of_real_less_number_of_iff

   star_of_le_number <-- hypreal_of_real_le_number_of_iff

   star_of_power <-- hypreal_of_real_power

   star_of_eq_0 <-- hcomplex_of_complex_zero_iff

 * Hyperreal: new method "transfer" that implements the transfer

 principle of nonstandard analysis. With a subgoal that mentions

 nonstandard types like "'a star", the command "apply transfer"

 replaces it with an equivalent one that mentions only standard types.

 To be successful, all free variables must have standard types; non-

 standard variables must have explicit universal quantifiers.

 * Hyperreal: A theory of Taylor series.

 *** HOLCF ***

 * Discontinued special version of 'constdefs' (which used to support

 continuous functions) in favor of the general Pure one with full

 type-inference.

 * New simplification procedure for solving continuity conditions; it

 is much faster on terms with many nested lambda abstractions (cubic

 instead of exponential time).

 * New syntax for domain package: selector names are now optional.

 Parentheses should be omitted unless argument is lazy, for example:

   domain 'a stream = cons "'a" (lazy "'a stream")

 * New command 'fixrec' for defining recursive functions with pattern

 matching; defining multiple functions with mutual recursion is also

 supported.  Patterns may include the constants cpair, spair, up, sinl,

 sinr, or any data constructor defined by the domain package. The given

 equations are proven as rewrite rules. See HOLCF/ex/Fixrec_ex.thy for

 syntax and examples.

 * New commands 'cpodef' and 'pcpodef' for defining predicate subtypes

 of cpo and pcpo types. Syntax is exactly like the 'typedef' command,

 but the proof obligation additionally includes an admissibility

 requirement. The packages generate instances of class cpo or pcpo,

 with continuity and strictness theorems for Rep and Abs.

 * HOLCF: Many theorems have been renamed according to a more standard naming

 scheme (INCOMPATIBILITY):

   foo_inject:  "foo$x = foo$y ==> x = y"

   foo_eq:      "(foo$x = foo$y) = (x = y)"

   foo_less:    "(foo$x << foo$y) = (x << y)"

   foo_strict:  "foo$UU = UU"

   foo_defined: "... ==> foo$x ~= UU"

   foo_defined_iff: "(foo$x = UU) = (x = UU)"

 *** ZF ***

 * ZF/ex: theories Group and Ring provide examples in abstract algebra,

 including the First Isomorphism Theorem (on quotienting by the kernel

 of a homomorphism).

 * ZF/Simplifier: install second copy of type solver that actually

 makes use of TC rules declared to Isar proof contexts (or locales);

 the old version is still required for ML proof scripts.

 *** Cube ***

 * Converted to Isar theory format; use locales instead of axiomatic

 theories.

 *** ML ***

 * Pure/library.ML: added ##>, ##>>, #>> -- higher-order counterparts

 for ||>, ||>>, |>>,

 * Pure/library.ML no longer defines its own option datatype, but uses

 that of the SML basis, which has constructors NONE and SOME instead of

 None and Some, as well as exception Option.Option instead of OPTION.

 The functions the, if_none, is_some, is_none have been adapted

 accordingly, while Option.map replaces apsome.

 * Pure/library.ML: the exception LIST has been given up in favour of

 the standard exceptions Empty and Subscript, as well as

 Library.UnequalLengths.  Function like Library.hd and Library.tl are

 superceded by the standard hd and tl functions etc.

 A number of basic list functions are no longer exported to the ML

 toplevel, as they are variants of predefined functions.  The following

 suggests how one can translate existing code:

     rev_append xs ys = List.revAppend (xs, ys)

     nth_elem (i, xs) = List.nth (xs, i)

     last_elem xs = List.last xs

     flat xss = List.concat xss

     seq fs = List.app fs

     partition P xs = List.partition P xs

     mapfilter f xs = List.mapPartial f xs

 * Pure/library.ML: several combinators for linear functional

 transformations, notably reverse application and composition:

   x |> f                f #> g

   (x, y) |-> f          f #-> g

 * Pure/library.ML: introduced/changed precedence of infix operators:

   infix 1 |> |-> ||> ||>> |>> |>>> #> #->;

   infix 2 ?;

   infix 3 o oo ooo oooo;

   infix 4 ~~ upto downto;

 Maybe INCOMPATIBILITY when any of those is used in conjunction with other

 infix operators.

 * Pure/library.ML: natural list combinators fold, fold_rev, and

 fold_map support linear functional transformations and nesting.  For

 example:

   fold f [x1, ..., xN] y =

     y |> f x1 |> ... |> f xN

   (fold o fold) f [xs1, ..., xsN] y =

     y |> fold f xs1 |> ... |> fold f xsN

   fold f [x1, ..., xN] =

     f x1 #> ... #> f xN

   (fold o fold) f [xs1, ..., xsN] =

     fold f xs1 #> ... #> fold f xsN

 * Pure/library.ML: the following selectors on type 'a option are

 available:

   the:               'a option -> 'a  (*partial*)

   these:             'a option -> 'a  where 'a = 'b list

   the_default: 'a -> 'a option -> 'a

   the_list:          'a option -> 'a list

 * Pure/General: structure AList (cf. Pure/General/alist.ML) provides

 basic operations for association lists, following natural argument

 order; moreover the explicit equality predicate passed here avoids

 potentially expensive polymorphic runtime equality checks.

 The old functions may be expressed as follows:

   assoc = uncurry (AList.lookup (op =))

   assocs = these oo AList.lookup (op =)

   overwrite = uncurry (AList.update (op =)) o swap

 * Pure/General: structure AList (cf. Pure/General/alist.ML) provides

   val make: ('a -> 'b) -> 'a list -> ('a * 'b) list

   val find: ('a * 'b -> bool) -> ('c * 'b) list -> 'a -> 'c list

 replacing make_keylist and keyfilter (occassionally used)

 Naive rewrites:

   make_keylist = AList.make

   keyfilter = AList.find (op =)

 * eq_fst and eq_snd now take explicit equality parameter, thus

   avoiding eqtypes. Naive rewrites:

     eq_fst = eq_fst (op =)

     eq_snd = eq_snd (op =)

 * Removed deprecated apl and apr (rarely used).

   Naive rewrites:

     apl (n, op) =>>= curry op n

     apr (op, m) =>>= fn n => op (n, m)

 * Pure/General: structure OrdList (cf. Pure/General/ord_list.ML)

 provides a reasonably efficient light-weight implementation of sets as

 lists.

 * Pure/General: generic tables (cf. Pure/General/table.ML) provide a

 few new operations; existing lookup and update are now curried to

 follow natural argument order (for use with fold etc.);

 INCOMPATIBILITY, use (uncurry Symtab.lookup) etc. as last resort.

 * Pure/General: output via the Isabelle channels of

 writeln/warning/error etc. is now passed through Output.output, with a

 hook for arbitrary transformations depending on the print_mode

 (cf. Output.add_mode -- the first active mode that provides a output

 function wins).  Already formatted output may be embedded into further

 text via Output.raw; the result of Pretty.string_of/str_of and derived

 functions (string_of_term/cterm/thm etc.) is already marked raw to

 accommodate easy composition of diagnostic messages etc.  Programmers

 rarely need to care about Output.output or Output.raw at all, with

 some notable exceptions: Output.output is required when bypassing the

 standard channels (writeln etc.), or in token translations to produce

 properly formatted results; Output.raw is required when capturing

 already output material that will eventually be presented to the user

 a second time.  For the default print mode, both Output.output and

 Output.raw have no effect.

 * Pure/General: Output.time_accumulator NAME creates an operator ('a

 -> 'b) -> 'a -> 'b to measure runtime and count invocations; the

 cumulative results are displayed at the end of a batch session.

 * Pure/General: File.sysify_path and File.quote_sysify path have been

 replaced by File.platform_path and File.shell_path (with appropriate

 hooks).  This provides a clean interface for unusual systems where the

 internal and external process view of file names are different.

 * Pure: more efficient orders for basic syntactic entities: added

 fast_string_ord, fast_indexname_ord, fast_term_ord; changed sort_ord

 and typ_ord to use fast_string_ord and fast_indexname_ord (term_ord is

 NOT affected); structures Symtab, Vartab, Typtab, Termtab use the fast

 orders now -- potential INCOMPATIBILITY for code that depends on a

 particular order for Symtab.keys, Symtab.dest, etc. (consider using

 Library.sort_strings on result).

 * Pure/term.ML: combinators fold_atyps, fold_aterms, fold_term_types,

 fold_types traverse types/terms from left to right, observing natural

 argument order.  Supercedes previous foldl_XXX versions, add_frees,

 add_vars etc. have been adapted as well: INCOMPATIBILITY.

 * Pure: name spaces have been refined, with significant changes of the

 internal interfaces -- INCOMPATIBILITY.  Renamed cond_extern(_table)

 to extern(_table).  The plain name entry path is superceded by a

 general 'naming' context, which also includes the 'policy' to produce

 a fully qualified name and external accesses of a fully qualified

 name; NameSpace.extend is superceded by context dependent

 Sign.declare_name.  Several theory and proof context operations modify

 the naming context.  Especially note Theory.restore_naming and

 ProofContext.restore_naming to get back to a sane state; note that

 Theory.add_path is no longer sufficient to recover from

 Theory.absolute_path in particular.

 * Pure: new flags short_names (default false) and unique_names

 (default true) for controlling output of qualified names.  If

 short_names is set, names are printed unqualified.  If unique_names is

 reset, the name prefix is reduced to the minimum required to achieve

 the original result when interning again, even if there is an overlap

 with earlier declarations.

 * Pure/TheoryDataFun: change of the argument structure; 'prep_ext' is

 now 'extend', and 'merge' gets an additional Pretty.pp argument

 (useful for printing error messages).  INCOMPATIBILITY.

 * Pure: major reorganization of the theory context.  Type Sign.sg and

 Theory.theory are now identified, referring to the universal

 Context.theory (see Pure/context.ML).  Actual signature and theory

 content is managed as theory data.  The old code and interfaces were

 spread over many files and structures; the new arrangement introduces

 considerable INCOMPATIBILITY to gain more clarity:

   Context -- theory management operations (name, identity, inclusion,

     parents, ancestors, merge, etc.), plus generic theory data;

   Sign -- logical signature and syntax operations (declaring consts,

     types, etc.), plus certify/read for common entities;

   Theory -- logical theory operations (stating axioms, definitions,

     oracles), plus a copy of logical signature operations (consts,

     types, etc.); also a few basic management operations (Theory.copy,

     Theory.merge, etc.)

 The most basic sign_of operations (Theory.sign_of, Thm.sign_of_thm

 etc.) as well as the sign field in Thm.rep_thm etc. have been retained

 for convenience -- they merely return the theory.

 * Pure: type Type.tsig is superceded by theory in most interfaces.

 * Pure: the Isar proof context type is already defined early in Pure

 as Context.proof (note that ProofContext.context and Proof.context are

 aliases, where the latter is the preferred name).  This enables other

 Isabelle components to refer to that type even before Isar is present.

 * Pure/sign/theory: discontinued named name spaces (i.e. classK,

 typeK, constK, axiomK, oracleK), but provide explicit operations for

 any of these kinds.  For example, Sign.intern typeK is now

 Sign.intern_type, Theory.hide_space Sign.typeK is now

 Theory.hide_types.  Also note that former

 Theory.hide_classes/types/consts are now

 Theory.hide_classes_i/types_i/consts_i, while the non '_i' versions

 internalize their arguments!  INCOMPATIBILITY.

 * Pure: get_thm interface (of PureThy and ProofContext) expects

 datatype thmref (with constructors Name and NameSelection) instead of

 plain string -- INCOMPATIBILITY;

 * Pure: cases produced by proof methods specify options, where NONE

 means to remove case bindings -- INCOMPATIBILITY in

 (RAW_)METHOD_CASES.

 * Pure: the following operations retrieve axioms or theorems from a

 theory node or theory hierarchy, respectively:

   Theory.axioms_of: theory -> (string * term) list

   Theory.all_axioms_of: theory -> (string * term) list

   PureThy.thms_of: theory -> (string * thm) list

   PureThy.all_thms_of: theory -> (string * thm) list

 * Pure: print_tac now outputs the goal through the trace channel.

 * Isar toplevel: improved diagnostics, mostly for Poly/ML only.

 Reference Toplevel.debug (default false) controls detailed printing

 and tracing of low-level exceptions; Toplevel.profiling (default 0)

 controls execution profiling -- set to 1 for time and 2 for space

 (both increase the runtime).

 * Isar session: The initial use of ROOT.ML is now always timed,

 i.e. the log will show the actual process times, in contrast to the

 elapsed wall-clock time that the outer shell wrapper produces.

 * Simplifier: improved handling of bound variables (nameless

 representation, avoid allocating new strings).  Simprocs that invoke

 the Simplifier recursively should use Simplifier.inherit_bounds to

 avoid local name clashes.  Failure to do so produces warnings

 "Simplifier: renamed bound variable ..."; set Simplifier.debug_bounds

 for further details.

 * ML functions legacy_bindings and use_legacy_bindings produce ML fact

 bindings for all theorems stored within a given theory; this may help

 in porting non-Isar theories to Isar ones, while keeping ML proof

 scripts for the time being.

 * ML operator HTML.with_charset specifies the charset begin used for

 generated HTML files.  For example:

   HTML.with_charset "utf-8" use_thy "Hebrew";

   HTML.with_charset "utf-8" use_thy "Chinese";

 *** System ***

 * Allow symlinks to all proper Isabelle executables (Isabelle,

 isabelle, isatool etc.).

 * ISABELLE_DOC_FORMAT setting specifies preferred document format (for

 isatool doc, isatool mkdir, display_drafts etc.).

 * isatool usedir: option -f allows specification of the ML file to be

 used by Isabelle; default is ROOT.ML.

 * New isatool version outputs the version identifier of the Isabelle

 distribution being used.

 * HOL: new isatool dimacs2hol converts files in DIMACS CNF format

 (containing Boolean satisfiability problems) into Isabelle/HOL

 theories.

 New in Isabelle2004 (April 2004)

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

 *** General ***

 * Provers/order.ML:  new efficient reasoner for partial and linear orders.

   Replaces linorder.ML.

 * Pure: Greek letters (except small lambda, \<lambda>), as well as Gothic

   (\<aa>...\<zz>\<AA>...\<ZZ>), calligraphic (\<A>...\<Z>), and Euler

   (\<a>...\<z>), are now considered normal letters, and can therefore

   be used anywhere where an ASCII letter (a...zA...Z) has until

   now. COMPATIBILITY: This obviously changes the parsing of some

   terms, especially where a symbol has been used as a binder, say

   '\<Pi>x. ...', which is now a type error since \<Pi>x will be parsed

   as an identifier.  Fix it by inserting a space around former

   symbols.  Call 'isatool fixgreek' to try to fix parsing errors in

   existing theory and ML files.

 * Pure: Macintosh and Windows line-breaks are now allowed in theory files.

 * Pure: single letter sub/superscripts (\<^isub> and \<^isup>) are now

   allowed in identifiers. Similar to Greek letters \<^isub> is now considered

   a normal (but invisible) letter. For multiple letter subscripts repeat

   \<^isub> like this: x\<^isub>1\<^isub>2.

 * Pure: There are now sub-/superscripts that can span more than one

   character. Text between \<^bsub> and \<^esub> is set in subscript in

   ProofGeneral and LaTeX, text between \<^bsup> and \<^esup> in

   superscript. The new control characters are not identifier parts.

 * Pure: Control-symbols of the form \<^raw:...> will literally print the

   content of "..." to the latex file instead of \isacntrl... . The "..."

   may consist of any printable characters excluding the end bracket >.

 * Pure: Using new Isar command "finalconsts" (or the ML functions

   Theory.add_finals or Theory.add_finals_i) it is now possible to

   declare constants "final", which prevents their being given a definition

   later.  It is useful for constants whose behaviour is fixed axiomatically

   rather than definitionally, such as the meta-logic connectives.

 * Pure: 'instance' now handles general arities with general sorts

   (i.e. intersections of classes),

 * Presentation: generated HTML now uses a CSS style sheet to make layout

   (somewhat) independent of content. It is copied from lib/html/isabelle.css.

   It can be changed to alter the colors/layout of generated pages.

 *** Isar ***

 * Tactic emulation methods rule_tac, erule_tac, drule_tac, frule_tac,

   cut_tac, subgoal_tac and thin_tac:

   - Now understand static (Isar) contexts.  As a consequence, users of Isar

     locales are no longer forced to write Isar proof scripts.

     For details see Isar Reference Manual, paragraph 4.3.2: Further tactic

     emulations.

   - INCOMPATIBILITY: names of variables to be instantiated may no

     longer be enclosed in quotes.  Instead, precede variable name with `?'.

     This is consistent with the instantiation attribute "where".

 * Attributes "where" and "of":

   - Now take type variables of instantiated theorem into account when reading

     the instantiation string.  This fixes a bug that caused instantiated

     theorems to have too special types in some circumstances.

   - "where" permits explicit instantiations of type variables.

 * Calculation commands "moreover" and "also" no longer interfere with

   current facts ("this"), admitting arbitrary combinations with "then"

   and derived forms.

 * Locales:

   - Goal statements involving the context element "includes" no longer

     generate theorems with internal delta predicates (those ending on

     "_axioms") in the premise.

     Resolve particular premise with <locale>.intro to obtain old form.

   - Fixed bug in type inference ("unify_frozen") that prevented mix of target

     specification and "includes" elements in goal statement.

   - Rule sets <locale>.intro and <locale>.axioms no longer declared as

     [intro?] and [elim?] (respectively) by default.

   - Experimental command for instantiation of locales in proof contexts:

         instantiate <label>[<attrs>]: <loc>

     Instantiates locale <loc> and adds all its theorems to the current context

     taking into account their attributes.  Label and attrs are optional

     modifiers, like in theorem declarations.  If present, names of

     instantiated theorems are qualified with <label>, and the attributes

     <attrs> are applied after any attributes these theorems might have already.

       If the locale has assumptions, a chained fact of the form

     "<loc> t1 ... tn" is expected from which instantiations of the parameters

     are derived.  The command does not support old-style locales declared

     with "locale (open)".

       A few (very simple) examples can be found in FOL/ex/LocaleInst.thy.

 * HOL: Tactic emulation methods induct_tac and case_tac understand static

   (Isar) contexts.

 *** HOL ***

 * Proof import: new image HOL4 contains the imported library from

   the HOL4 system with about 2500 theorems. It is imported by

   replaying proof terms produced by HOL4 in Isabelle. The HOL4 image

   can be used like any other Isabelle image.  See

   HOL/Import/HOL/README for more information.

 * Simplifier:

   - Much improved handling of linear and partial orders.

     Reasoners for linear and partial orders are set up for type classes

     "linorder" and "order" respectively, and are added to the default simpset

     as solvers.  This means that the simplifier can build transitivity chains

     to solve goals from the assumptions.

   - INCOMPATIBILITY: old proofs break occasionally.  Typically, applications

     of blast or auto after simplification become unnecessary because the goal

     is solved by simplification already.

 * Numerics: new theory Ring_and_Field contains over 250 basic numerical laws,

     all proved in axiomatic type classes for semirings, rings and fields.

 * Numerics:

   - Numeric types (nat, int, and in HOL-Complex rat, real, complex, etc.) are

     now formalized using the Ring_and_Field theory mentioned above.

   - INCOMPATIBILITY: simplification and arithmetic behaves somewhat differently

     than before, because now they are set up once in a generic manner.

   - INCOMPATIBILITY: many type-specific arithmetic laws have gone.

     Look for the general versions in Ring_and_Field (and Power if they concern

     exponentiation).

 * Type "rat" of the rational numbers is now available in HOL-Complex.

 * Records:

   - Record types are now by default printed with their type abbreviation

     instead of the list of all field types. This can be configured via

     the reference "print_record_type_abbr".

   - Simproc "record_upd_simproc" for simplification of multiple updates added

     (not enabled by default).

   - Simproc "record_ex_sel_eq_simproc" to simplify EX x. sel r = x resp.

     EX x. x = sel r to True (not enabled by default).

   - Tactic "record_split_simp_tac" to split and simplify records added.

 * 'specification' command added, allowing for definition by

   specification.  There is also an 'ax_specification' command that

   introduces the new constants axiomatically.

 * arith(_tac) is now able to generate counterexamples for reals as well.

 * HOL-Algebra: new locale "ring" for non-commutative rings.

 * HOL-ex: InductiveInvariant_examples illustrates advanced recursive function

   definitions, thanks to Sava Krsti\'{c} and John Matthews.

 * HOL-Matrix: a first theory for matrices in HOL with an application of

   matrix theory to linear programming.

 * Unions and Intersections:

   The latex output syntax of UN and INT has been changed

   from "\Union x \in A. B" to "\Union_{x \in A} B"

   i.e. the index formulae has become a subscript.

   Similarly for "\Union x. B", and for \Inter instead of \Union.

 * Unions and Intersections over Intervals:

   There is new short syntax "UN i<=n. A" for "UN i:{0..n}. A". There is

   also an x-symbol version with subscripts "\<Union>\<^bsub>i <= n\<^esub>. A"

   like in normal math, and corresponding versions for < and for intersection.

 * HOL/List: Ordering "lexico" is renamed "lenlex" and the standard

   lexicographic dictonary ordering has been added as "lexord".

 * ML: the legacy theory structures Int and List have been removed. They had

   conflicted with ML Basis Library structures having the same names.

 * 'refute' command added to search for (finite) countermodels.  Only works

   for a fragment of HOL.  The installation of an external SAT solver is

   highly recommended.  See "HOL/Refute.thy" for details.

 * 'quickcheck' command: Allows to find counterexamples by evaluating

   formulae under an assignment of free variables to random values.

   In contrast to 'refute', it can deal with inductive datatypes,

   but cannot handle quantifiers. See "HOL/ex/Quickcheck_Examples.thy"

   for examples.

 *** HOLCF ***

 * Streams now come with concatenation and are part of the HOLCF image

 New in Isabelle2003 (May 2003)

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

 *** General ***

 * Provers/simplifier:

   - Completely reimplemented method simp (ML: Asm_full_simp_tac):

     Assumptions are now subject to complete mutual simplification,

     not just from left to right. The simplifier now preserves

     the order of assumptions.

     Potential INCOMPATIBILITY:

     -- simp sometimes diverges where the old version did

        not, e.g. invoking simp on the goal

         [| P (f x); y = x; f x = f y |] ==> Q

        now gives rise to the infinite reduction sequence

         P(f x) --(f x = f y)--> P(f y) --(y = x)--> P(f x) --(f x = f y)--> ...

        Using "simp (asm_lr)" (ML: Asm_lr_simp_tac) instead often solves this

        kind of problem.

     -- Tactics combining classical reasoner and simplification (such as auto)

        are also affected by this change, because many of them rely on

        simp. They may sometimes diverge as well or yield a different numbers

        of subgoals. Try to use e.g. force, fastsimp, or safe instead of auto

        in case of problems. Sometimes subsequent calls to the classical

        reasoner will fail because a preceeding call to the simplifier too

        eagerly simplified the goal, e.g. deleted redundant premises.

   - The simplifier trace now shows the names of the applied rewrite rules

   - You can limit the number of recursive invocations of the simplifier

     during conditional rewriting (where the simplifie tries to solve the

     conditions before applying the rewrite rule):

     ML "simp_depth_limit := n"

     where n is an integer. Thus you can force termination where previously

     the simplifier would diverge.

   - Accepts free variables as head terms in congruence rules.  Useful in Isar.

   - No longer aborts on failed congruence proof.  Instead, the

     congruence is ignored.

 * Pure: New generic framework for extracting programs from constructive

   proofs. See HOL/Extraction.thy for an example instantiation, as well

   as HOL/Extraction for some case studies.

 * Pure: The main goal of the proof state is no longer shown by default, only

 the subgoals. This behaviour is controlled by a new flag.

    PG menu: Isabelle/Isar -> Settings -> Show Main Goal

 (ML: Proof.show_main_goal).

 * Pure: You can find all matching introduction rules for subgoal 1, i.e. all

 rules whose conclusion matches subgoal 1:

       PG menu: Isabelle/Isar -> Show me -> matching rules