NEWS

* Pure/sign/theory: discontinued named name spaces;
* Pure: Theory.axioms_of, PureThy.thms_of etc.;

Isabelle NEWS -- history user-relevant changes
==============================================

New in this Isabelle release
----------------------------

*** 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.  Note that there is no change in
ancient non-Isar theories.

* Theory loader: parent theories can now also be referred to via
relative and absolute paths.

* Improved version of thms_containing 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).


*** 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).

* There is now a flag to control hiding of proofs and some other
commands (such as 'ML' or 'parse/print_translation') in document
output.  Hiding is enabled by default, and can be disabled by the
option '-H false' of isatool usedir or by resetting the reference
variable IsarOutput.hide_commands in ML.  Additional commands to be
hidden may be declared using IsarOutput.add_hidden_commands.

* Several new antiquotation:

  @{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

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' .. 'prem9'
to print the specified premise.  TermStyle.add_style provides an ML
interface for introducing further styles.  See also the "LaTeX Sugar"
document practical applications.


*** 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 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 pinter 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/Base.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.

* 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 ==>.

* 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.


*** Locales ***
  
* New commands for the interpretation of locale expressions in
theories ('interpretation') and proof contexts ('interpret').  These
take an instantiation of the locale parameters and compute proof
obligations from the instantiated specification.  After the
obligations have been discharged, the instantiated theorems of the
locale are added to the theory or proof context.  Interpretation is
smart in that already active interpretations 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.

INCOMPATIBILITY: former 'instantiate' has been withdrawn, use
'interpret' instead.

* 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.

* New context element "constrains" adds type constraints to parameters --
there is no logical significance.

* Context expressions: renaming parameters permits syntax
redeclaration as well.

* Locale definition: 'includes' now disallowed.

* Changed parameter management in theorem generation for long goal
statements with 'includes'.  INCOMPATIBILITY: produces a different
theorem statement in rare situations.

* Attributes 'induct' and 'cases': type or set names may now be
locally fixed variables as well.

* Antiquotations now provide the option 'locale=NAME' to specify an
alternative context used for evaluating and printing the subsequent
argument, as in @{thm [locale=LC] fold_commute}, for example.


*** 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>.

* "{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 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".

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.

* 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.

* 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.


*** HOLCF ***

* HOLCF: discontinued special version of 'constdefs' (which used to
support continuous functions) in favor of the general Pure one with
full type-inference.


*** 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.


*** ML ***

* 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.

* 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 functions are now no longer exported to the ML
toplevel, as they are variants of standard 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
    filter P xs = List.filter P xs
    mapfilter f xs = List.mapPartial f xs

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

* Isar debugging: new reference Toplevel.debug; default false.  Set to
make printing of exceptions THM, TERM, TYPE and THEORY more verbose.

* 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/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: 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

* Provers: Simplifier and Classical Reasoner now support proof context
dependent plug-ins (simprocs, solvers, wrappers etc.).  These extra
components are stored in the theory and patched into the
simpset/claset when used in an Isar proof context.  Context dependent
components are maintained by the following theory operations:

  Simplifier.add_context_simprocs
  Simplifier.del_context_simprocs
  Simplifier.set_context_subgoaler
  Simplifier.reset_context_subgoaler
  Simplifier.add_context_looper
  Simplifier.del_context_looper
  Simplifier.add_context_unsafe_solver
  Simplifier.add_context_safe_solver

  Classical.add_context_safe_wrapper
  Classical.del_context_safe_wrapper
  Classical.add_context_unsafe_wrapper
  Classical.del_context_unsafe_wrapper

IMPORTANT NOTE: proof tools (methods etc.) need to use
local_simpset_of and local_claset_of to instead of the primitive
Simplifier.get_local_simpset and Classical.get_local_claset,
respectively, in order to see the context dependent fields!

* 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.


*** 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
The rules are ordered by how closely they match the subgoal.
In particular, rules that solve a subgoal outright are displayed first
(or rather last, the way they are printed).
(ML: ProofGeneral.print_intros())

* Pure: New flag trace_unify_fail causes unification to print
diagnostic information (PG: in trace buffer) when it fails. This is
useful for figuring out why single step proofs like rule, erule or
assumption failed.

* Pure: Locale specifications now produce predicate definitions
according to the body of text (covering assumptions modulo local
definitions); predicate "loc_axioms" covers newly introduced text,
while "loc" is cumulative wrt. all included locale expressions; the
latter view is presented only on export into the global theory
context; potential INCOMPATIBILITY, use "(open)" option to fall back
on the old view without predicates;

* Pure: predefined locales "var" and "struct" are useful for sharing
parameters (as in CASL, for example); just specify something like
``var x + var y + struct M'' as import;

* Pure: improved thms_containing: proper indexing of facts instead of
raw theorems; check validity of results wrt. current name space;
include local facts of proof configuration (also covers active
locales), cover fixed variables in index; may use "_" in term
specification; an optional limit for the number of printed facts may
be given (the default is 40);

* Pure: disallow duplicate fact bindings within new-style theory files
(batch-mode only);

* Provers: improved induct method: assumptions introduced by case
"foo" are split into "foo.hyps" (from the rule) and "foo.prems" (from
the goal statement); "foo" still refers to all facts collectively;

* Provers: the function blast.overloaded has been removed: all constants
are regarded as potentially overloaded, which improves robustness in exchange
for slight decrease in efficiency;

* Provers/linorder: New generic prover for transitivity reasoning over
linear orders.  Note: this prover is not efficient!

* Isar: preview of problems to finish 'show' now produce an error
rather than just a warning (in interactive mode);


*** HOL ***

* arith(_tac)

 - Produces a counter example if it cannot prove a goal.
   Note that the counter example may be spurious if the goal is not a formula
   of quantifier-free linear arithmetic.
   In ProofGeneral the counter example appears in the trace buffer.

 - Knows about div k and mod k where k is a numeral of type nat or int.

 - Calls full Presburger arithmetic (by Amine Chaieb) if quantifier-free
   linear arithmetic fails. This takes account of quantifiers and divisibility.
   Presburger arithmetic can also be called explicitly via presburger(_tac).

* simp's arithmetic capabilities have been enhanced a bit: it now
takes ~= in premises into account (by performing a case split);

* simp reduces "m*(n div m) + n mod m" to n, even if the two summands
are distributed over a sum of terms;

* New tactic "trans_tac" and method "trans" instantiate
Provers/linorder.ML for axclasses "order" and "linorder" (predicates
"<=", "<" and "=").

* function INCOMPATIBILITIES: Pi-sets have been redefined and moved from main
HOL to Library/FuncSet; constant "Fun.op o" is now called "Fun.comp";

* 'typedef' command has new option "open" to suppress the set
definition;

* functions Min and Max on finite sets have been introduced (theory
Finite_Set);

* attribute [symmetric] now works for relations as well; it turns
(x,y) : R^-1 into (y,x) : R, and vice versa;

* induct over a !!-quantified statement (say !!x1..xn):
  each "case" automatically performs "fix x1 .. xn" with exactly those names.

* Map: `empty' is no longer a constant but a syntactic abbreviation for
%x. None. Warning: empty_def now refers to the previously hidden definition
of the empty set.

* Algebra: formalization of classical algebra.  Intended as base for
any algebraic development in Isabelle.  Currently covers group theory
(up to Sylow's theorem) and ring theory (Universal Property of
Univariate Polynomials).  Contributions welcome;

* GroupTheory: deleted, since its material has been moved to Algebra;

* Complex: new directory of the complex numbers with numeric constants,
nonstandard complex numbers, and some complex analysis, standard and
nonstandard (Jacques Fleuriot);

* HOL-Complex: new image for analysis, replacing HOL-Real and HOL-Hyperreal;

* Hyperreal: introduced Gauge integration and hyperreal logarithms (Jacques
Fleuriot);

* Real/HahnBanach: updated and adapted to locales;

* NumberTheory: added Gauss's law of quadratic reciprocity (by Avigad,
Gray and Kramer);

* UNITY: added the Meier-Sanders theory of progress sets;

* MicroJava: bytecode verifier and lightweight bytecode verifier
as abstract algorithms, instantiated to the JVM;

* Bali: Java source language formalization. Type system, operational
semantics, axiomatic semantics. Supported language features:
classes, interfaces, objects,virtual methods, static methods,
static/instance fields, arrays, access modifiers, definite
assignment, exceptions.


*** ZF ***

* ZF/Constructible: consistency proof for AC (Gdel's constructible
universe, etc.);

* Main ZF: virtually all theories converted to new-style format;


*** ML ***

* Pure: Tactic.prove provides sane interface for internal proofs;
omits the infamous "standard" operation, so this is more appropriate
than prove_goalw_cterm in many situations (e.g. in simprocs);

* Pure: improved error reporting of simprocs;

* Provers: Simplifier.simproc(_i) provides sane interface for setting
up simprocs;


*** Document preparation ***

* uses \par instead of \\ for line breaks in theory text. This may
shift some page breaks in large documents. To get the old behaviour
use \renewcommand{\isanewline}{\mbox{}\\\mbox{}} in root.tex.

* minimized dependencies of isabelle.sty and isabellesym.sty on
other packages

* \<euro> now needs package babel/greek instead of marvosym (which
broke \Rightarrow)

* normal size for \<zero>...\<nine> (uses \mathbf instead of
textcomp package)



New in Isabelle2002 (March 2002)
--------------------------------

*** Document preparation ***

* greatly simplified document preparation setup, including more
graceful interpretation of isatool usedir -i/-d/-D options, and more
instructive isatool mkdir; users should basically be able to get
started with "isatool mkdir HOL Test && isatool make"; alternatively,
users may run a separate document processing stage manually like this:
"isatool usedir -D output HOL Test && isatool document Test/output";

* theory dependency graph may now be incorporated into documents;
isatool usedir -g true will produce session_graph.eps/.pdf for use
with \includegraphics of LaTeX;

* proper spacing of consecutive markup elements, especially text
blocks after section headings;

* support bold style (for single symbols only), input syntax is like
this: "\<^bold>\<alpha>" or "\<^bold>A";

* \<bullet> is now output as bold \cdot by default, which looks much
better in printed text;

* added default LaTeX bindings for \<tturnstile> and \<TTurnstile>;
note that these symbols are currently unavailable in Proof General /
X-Symbol; new symbols \<zero>, \<one>, ..., \<nine>, and \<euro>;

* isatool latex no longer depends on changed TEXINPUTS, instead
isatool document copies the Isabelle style files to the target
location;


*** Isar ***

* Pure/Provers: improved proof by cases and induction;
  - 'case' command admits impromptu naming of parameters (such as
    "case (Suc n)");
  - 'induct' method divinates rule instantiation from the inductive
    claim; no longer requires excessive ?P bindings for proper
    instantiation of cases;
  - 'induct' method properly enumerates all possibilities of set/type
    rules; as a consequence facts may be also passed through *type*
    rules without further ado;
  - 'induct' method now derives symbolic cases from the *rulified*
    rule (before it used to rulify cases stemming from the internal
    atomized version); this means that the context of a non-atomic
    statement becomes is included in the hypothesis, avoiding the
    slightly cumbersome show "PROP ?case" form;
  - 'induct' may now use elim-style induction rules without chaining
    facts, using ``missing'' premises from the goal state; this allows
    rules stemming from inductive sets to be applied in unstructured
    scripts, while still benefitting from proper handling of non-atomic
    statements; NB: major inductive premises need to be put first, all
    the rest of the goal is passed through the induction;
  - 'induct' proper support for mutual induction involving non-atomic
    rule statements (uses the new concept of simultaneous goals, see
    below);
  - append all possible rule selections, but only use the first
    success (no backtracking);
  - removed obsolete "(simplified)" and "(stripped)" options of methods;
  - undeclared rule case names default to numbers 1, 2, 3, ...;
  - added 'print_induct_rules' (covered by help item in recent Proof
    General versions);
  - moved induct/cases attributes to Pure, methods to Provers;
  - generic method setup instantiated for FOL and HOL;

* Pure: support multiple simultaneous goal statements, for example
"have a: A and b: B" (same for 'theorem' etc.); being a pure
meta-level mechanism, this acts as if several individual goals had
been stated separately; in particular common proof methods need to be
repeated in order to cover all claims; note that a single elimination
step is *not* sufficient to establish the two conjunctions, so this
fails:

  assume "A & B" then have A and B ..   (*".." fails*)

better use "obtain" in situations as above; alternative refer to
multi-step methods like 'auto', 'simp_all', 'blast+' etc.;

* Pure: proper integration with ``locales''; unlike the original
version by Florian Kammller, Isar locales package high-level proof
contexts rather than raw logical ones (e.g. we admit to include
attributes everywhere); operations on locales include merge and
rename; support for implicit arguments (``structures''); simultaneous
type-inference over imports and text; see also HOL/ex/Locales.thy for
some examples;

* Pure: the following commands have been ``localized'', supporting a
target locale specification "(in name)": 'lemma', 'theorem',
'corollary', 'lemmas', 'theorems', 'declare'; the results will be
stored both within the locale and at the theory level (exported and
qualified by the locale name);

* Pure: theory goals may now be specified in ``long'' form, with
ad-hoc contexts consisting of arbitrary locale elements. for example
``lemma foo: fixes x assumes "A x" shows "B x"'' (local syntax and
definitions may be given, too); the result is a meta-level rule with
the context elements being discharged in the obvious way;

* Pure: new proof command 'using' allows to augment currently used
facts after a goal statement ('using' is syntactically analogous to
'apply', but acts on the goal's facts only); this allows chained facts
to be separated into parts given before and after a claim, as in
``from a and b have C using d and e <proof>'';

* Pure: renamed "antecedent" case to "rule_context";

* Pure: new 'judgment' command records explicit information about the
object-logic embedding (used by several tools internally); no longer
use hard-wired "Trueprop";

* Pure: added 'corollary' command;

* Pure: fixed 'token_translation' command;

* Pure: removed obsolete 'exported' attribute;

* Pure: dummy pattern "_" in is/let is now automatically lifted over
bound variables: "ALL x. P x --> Q x" (is "ALL x. _ --> ?C x")
supersedes more cumbersome ... (is "ALL x. _ x --> ?C x");

* Pure: method 'atomize' presents local goal premises as object-level
statements (atomic meta-level propositions); setup controlled via
rewrite rules declarations of 'atomize' attribute; example
application: 'induct' method with proper rule statements in improper
proof *scripts*;

* Pure: emulation of instantiation tactics (rule_tac, cut_tac, etc.)
now consider the syntactic context of assumptions, giving a better
chance to get type-inference of the arguments right (this is
especially important for locales);

* Pure: "sorry" no longer requires quick_and_dirty in interactive
mode;

* Pure/obtain: the formal conclusion "thesis", being marked as
``internal'', may no longer be reference directly in the text;
potential INCOMPATIBILITY, may need to use "?thesis" in rare
situations;

* Pure: generic 'sym' attribute which declares a rule both as pure
'elim?' and for the 'symmetric' operation;

* Pure: marginal comments ``--'' may now occur just anywhere in the
text; the fixed correlation with particular command syntax has been
discontinued;

* Pure: new method 'rules' is particularly well-suited for proof
search in intuitionistic logic; a bit slower than 'blast' or 'fast',
but often produces more compact proof terms with less detours;

* Pure/Provers/classical: simplified integration with pure rule
attributes and methods; the classical "intro?/elim?/dest?"
declarations coincide with the pure ones; the "rule" method no longer
includes classically swapped intros; "intro" and "elim" methods no
longer pick rules from the context; also got rid of ML declarations
AddXIs/AddXEs/AddXDs; all of this has some potential for
INCOMPATIBILITY;

* Provers/classical: attribute 'swapped' produces classical inversions
of introduction rules;

* Provers/simplifier: 'simplified' attribute may refer to explicit
rules instead of full simplifier context; 'iff' attribute handles
conditional rules;

* HOL: 'typedef' now allows alternative names for Rep/Abs morphisms;

* HOL: 'recdef' now fails on unfinished automated proofs, use
"(permissive)" option to recover old behavior;

* HOL: 'inductive' no longer features separate (collective) attributes
for 'intros' (was found too confusing);

* HOL: properly declared induction rules less_induct and
wf_induct_rule;


*** HOL ***

* HOL: moved over to sane numeral syntax; the new policy is as
follows:

  - 0 and 1 are polymorphic constants, which are defined on any
  numeric type (nat, int, real etc.);

  - 2, 3, 4, ... and -1, -2, -3, ... are polymorphic numerals, based
  binary representation internally;

  - type nat has special constructor Suc, and generally prefers Suc 0
  over 1::nat and Suc (Suc 0) over 2::nat;

This change may cause significant problems of INCOMPATIBILITY; here
are some hints on converting existing sources:

  - due to the new "num" token, "-0" and "-1" etc. are now atomic
  entities, so expressions involving "-" (unary or binary minus) need
  to be spaced properly;

  - existing occurrences of "1" may need to be constraint "1::nat" or
  even replaced by Suc 0; similar for old "2";

  - replace "#nnn" by "nnn", and "#-nnn" by "-nnn";

  - remove all special provisions on numerals in proofs;

* HOL: simp rules nat_number expand numerals on nat to Suc/0
representation (depends on bin_arith_simps in the default context);

* HOL: symbolic syntax for x^2 (numeral 2);

* HOL: the class of all HOL types is now called "type" rather than
"term"; INCOMPATIBILITY, need to adapt references to this type class
in axclass/classes, instance/arities, and (usually rare) occurrences
in typings (of consts etc.); internally the class is called
"HOL.type", ML programs should refer to HOLogic.typeS;

* HOL/record package improvements:
  - new derived operations "fields" to build a partial record section,
    "extend" to promote a fixed record to a record scheme, and
    "truncate" for the reverse; cf. theorems "xxx.defs", which are *not*
    declared as simp by default;
  - shared operations ("more", "fields", etc.) now need to be always
    qualified) --- potential INCOMPATIBILITY;
  - removed "make_scheme" operations (use "make" with "extend") --
    INCOMPATIBILITY;
  - removed "more" class (simply use "term") -- INCOMPATIBILITY;
  - provides cases/induct rules for use with corresponding Isar
    methods (for concrete records, record schemes, concrete more
    parts, and schematic more parts -- in that order);
  - internal definitions directly based on a light-weight abstract
    theory of product types over typedef rather than datatype;

* HOL: generic code generator for generating executable ML code from
specifications; specific support for HOL constructs such as inductive
datatypes and sets, as well as recursive functions; can be invoked
via 'generate_code' theory section;

* HOL: canonical cases/induct rules for n-tuples (n = 3..7);

* HOL: consolidated and renamed several theories.  In particular:
        Ord.thy has been absorbed into HOL.thy
        String.thy has been absorbed into List.thy

* HOL: concrete setsum syntax "\<Sum>i:A. b" == "setsum (%i. b) A"
(beware of argument permutation!);

* HOL: linorder_less_split superseded by linorder_cases;

* HOL/List: "nodups" renamed to "distinct";

* HOL: added "The" definite description operator; move Hilbert's "Eps"
to peripheral theory "Hilbert_Choice"; some INCOMPATIBILITIES:
  - Ex_def has changed, now need to use some_eq_ex

* HOL: made split_all_tac safe; EXISTING PROOFS MAY FAIL OR LOOP, so
in this (rare) case use:

  delSWrapper "split_all_tac"
  addSbefore ("unsafe_split_all_tac", unsafe_split_all_tac)

* HOL: added safe wrapper "split_conv_tac" to claset; EXISTING PROOFS
MAY FAIL;

* HOL: introduced f^n = f o ... o f; warning: due to the limits of
Isabelle's type classes, ^ on functions and relations has too general
a domain, namely ('a * 'b) set and 'a => 'b; this means that it may be
necessary to attach explicit type constraints;

* HOL/Relation: the prefix name of the infix "O" has been changed from
"comp" to "rel_comp"; INCOMPATIBILITY: a few theorems have been
renamed accordingly (eg "compI" -> "rel_compI").

* HOL: syntax translations now work properly with numerals and records
expressions;

* HOL: bounded abstraction now uses syntax "%" / "\<lambda>" instead
of "lam" -- INCOMPATIBILITY;

* HOL: got rid of some global declarations (potential INCOMPATIBILITY
for ML tools): const "()" renamed "Product_Type.Unity", type "unit"
renamed "Product_Type.unit";

* HOL: renamed rtrancl_into_rtrancl2 to converse_rtrancl_into_rtrancl

* HOL: removed obsolete theorem "optionE" (use "option.exhaust", or
the "cases" method);

* HOL/GroupTheory: group theory examples including Sylow's theorem (by
Florian Kammller);

* HOL/IMP: updated and converted to new-style theory format; several
parts turned into readable document, with proper Isar proof texts and
some explanations (by Gerwin Klein);

* HOL-Real: added Complex_Numbers (by Gertrud Bauer);

* HOL-Hyperreal is now a logic image;


*** HOLCF ***

* Isar: consts/constdefs supports mixfix syntax for continuous
operations;

* Isar: domain package adapted to new-style theory format, e.g. see
HOLCF/ex/Dnat.thy;

* theory Lift: proper use of rep_datatype lift instead of ML hacks --
potential INCOMPATIBILITY; now use plain induct_tac instead of former
lift.induct_tac, always use UU instead of Undef;

* HOLCF/IMP: updated and converted to new-style theory;


*** ZF ***

* Isar: proper integration of logic-specific tools and packages,
including theory commands '(co)inductive', '(co)datatype',
'rep_datatype', 'inductive_cases', as well as methods 'ind_cases',
'induct_tac', 'case_tac', and 'typecheck' (with attribute 'TC');

* theory Main no longer includes AC; for the Axiom of Choice, base
your theory on Main_ZFC;

* the integer library now covers quotients and remainders, with many
laws relating division to addition, multiplication, etc.;

* ZF/UNITY: Chandy and Misra's UNITY is now available in ZF, giving a
typeless version of the formalism;

* ZF/AC, Coind, IMP, Resid: updated and converted to new-style theory
format;

* ZF/Induct: new directory for examples of inductive definitions,
including theory Multiset for multiset orderings; converted to
new-style theory format;

* ZF: many new theorems about lists, ordinals, etc.;


*** General ***

* Pure/kernel: meta-level proof terms (by Stefan Berghofer); reference
variable proof controls level of detail: 0 = no proofs (only oracle
dependencies), 1 = lemma dependencies, 2 = compact proof terms; see
also ref manual for further ML interfaces;

* Pure/axclass: removed obsolete ML interface
goal_subclass/goal_arity;

* Pure/syntax: new token syntax "num" for plain numerals (without "#"
of "xnum"); potential INCOMPATIBILITY, since -0, -1 etc. are now
separate tokens, so expressions involving minus need to be spaced
properly;

* Pure/syntax: support non-oriented infixes, using keyword "infix"
rather than "infixl" or "infixr";

* Pure/syntax: concrete syntax for dummy type variables admits genuine
sort constraint specifications in type inference; e.g. "x::_::foo"
ensures that the type of "x" is of sort "foo" (but not necessarily a
type variable);

* Pure/syntax: print modes "type_brackets" and "no_type_brackets"
control output of nested => (types); the default behavior is
"type_brackets";

* Pure/syntax: builtin parse translation for "_constify" turns valued
tokens into AST constants;

* Pure/syntax: prefer later declarations of translations and print
translation functions; potential INCOMPATIBILITY: need to reverse
multiple declarations for same syntax element constant;

* Pure/show_hyps reset by default (in accordance to existing Isar
practice);

* Provers/classical: renamed addaltern to addafter, addSaltern to
addSafter;

* Provers/clasimp: ``iff'' declarations now handle conditional rules
as well;

* system: tested support for MacOS X; should be able to get Isabelle +
Proof General to work in a plain Terminal after installing Poly/ML
(e.g. from the Isabelle distribution area) and GNU bash alone
(e.g. from http://www.apple.com); full X11, XEmacs and X-Symbol
support requires further installations, e.g. from
http://fink.sourceforge.net/);

* system: support Poly/ML 4.1.1 (able to manage larger heaps);

* system: reduced base memory usage by Poly/ML (approx. 20 MB instead
of 40 MB), cf. ML_OPTIONS;

* system: Proof General keywords specification is now part of the
Isabelle distribution (see etc/isar-keywords.el);

* system: support for persistent Proof General sessions (refrain from
outdating all loaded theories on startup); user may create writable
logic images like this: ``isabelle -q HOL Test'';

* system: smart selection of Isabelle process versus Isabelle
interface, accommodates case-insensitive file systems (e.g. HFS+); may
run both "isabelle" and "Isabelle" even if file names are badly
damaged (executable inspects the case of the first letter of its own
name); added separate "isabelle-process" and "isabelle-interface";

* system: refrain from any attempt at filtering input streams; no
longer support ``8bit'' encoding of old isabelle font, instead proper
iso-latin characters may now be used; the related isatools
"symbolinput" and "nonascii" have disappeared as well;

* system: removed old "xterm" interface (the print modes "xterm" and
"xterm_color" are still available for direct use in a suitable
terminal);



New in Isabelle99-2 (February 2001)
-----------------------------------

*** Overview of INCOMPATIBILITIES ***

* HOL: please note that theories in the Library and elsewhere often use the
new-style (Isar) format; to refer to their theorems in an ML script you must
bind them to ML identifers by e.g.      val thm_name = thm "thm_name";

* HOL: inductive package no longer splits induction rule aggressively,
but only as far as specified by the introductions given; the old
format may be recovered via ML function complete_split_rule or attribute
'split_rule (complete)';

* HOL: induct renamed to lfp_induct, lfp_Tarski to lfp_unfold,
gfp_Tarski to gfp_unfold;

* HOL: contrapos, contrapos2 renamed to contrapos_nn, contrapos_pp;

* HOL: infix "dvd" now has priority 50 rather than 70 (because it is a
relation); infix "^^" has been renamed "``"; infix "``" has been
renamed "`"; "univalent" has been renamed "single_valued";

* HOL/Real: "rinv" and "hrinv" replaced by overloaded "inverse"
operation;

* HOLCF: infix "`" has been renamed "$"; the symbol syntax is \<cdot>;

* Isar: 'obtain' no longer declares "that" fact as simp/intro;

* Isar/HOL: method 'induct' now handles non-atomic goals; as a
consequence, it is no longer monotonic wrt. the local goal context
(which is now passed through the inductive cases);

* Document preparation: renamed standard symbols \<ll> to \<lless> and
\<gg> to \<ggreater>;


*** Document preparation ***

* \isabellestyle{NAME} selects version of Isabelle output (currently
available: are "it" for near math-mode best-style output, "sl" for
slanted text style, and "tt" for plain type-writer; if no
\isabellestyle command is given, output is according to slanted
type-writer);

* support sub/super scripts (for single symbols only), input syntax is
like this: "A\<^sup>*" or "A\<^sup>\<star>";

* some more standard symbols; see Appendix A of the system manual for
the complete list of symbols defined in isabellesym.sty;

* improved isabelle style files; more abstract symbol implementation
(should now use \isamath{...} and \isatext{...} in custom symbol
definitions);

* antiquotation @{goals} and @{subgoals} for output of *dynamic* goals
state; Note that presentation of goal states does not conform to
actual human-readable proof documents.  Please do not include goal
states into document output unless you really know what you are doing!

* proper indentation of antiquoted output with proportional LaTeX
fonts;

* no_document ML operator temporarily disables LaTeX document
generation;

* isatool unsymbolize tunes sources for plain ASCII communication;


*** Isar ***

* Pure: Isar now suffers initial goal statements to contain unbound
schematic variables (this does not conform to actual readable proof
documents, due to unpredictable outcome and non-compositional proof
checking); users who know what they are doing may use schematic goals
for Prolog-style synthesis of proven results;

* Pure: assumption method (an implicit finishing) now handles actual
rules as well;

* Pure: improved 'obtain' --- moved to Pure, insert "that" into