Isabelle NEWS -- history user-relevant changes

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

New in this Isabelle version

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

*** Overview of INCOMPATIBILITIES (see below for more details) ***

* HOL: simplification of natural numbers is much changed; to partly

recover the old behaviour (e.g. to prevent n+n rewriting to #2*n)

issue the following ML commands:

  Delsimprocs Nat_Numeral_Simprocs.cancel_numerals;

  Delsimprocs [Nat_Numeral_Simprocs.combine_numerals];

* HOL: 0 is now overloaded, so the type constraint ::nat may sometimes be

needed;

* HOL: the constant for f``x is now "image" rather than "op ``";

* HOL: the disjoint sum is now "<+>" instead of "Plus"; the cartesian

product is now "<*>" instead of "Times"; the lexicographic product is

now "<*lex*>" instead of "**";

* HOL: exhaust_tac on datatypes superceded by new generic case_tac;

* HOL: simplification no longer dives into case-expressions

* HOL: the recursion equations generated by 'recdef' are now called

f.simps instead of f.rules;

* HOL: theory Sexp now in HOL/Induct examples (used to be part of main

HOL, but was unused); should better use HOL's datatype package anyway;

* HOL: removed obsolete theorem binding expand_if, use split_if instead;

* HOL/Real: "rabs" replaced by overloaded "abs" function;

* HOL/ML: even fewer consts are declared as global (see theories Ord,

Lfp, Gfp, WF); this only affects ML packages that refer to const names

internally;

* HOL, ZF: syntax for quotienting wrt an equivalence relation changed from

  A/r to A//r;

* Isar: changed syntax of local blocks from {{ }} to { };

* Isar/Provers: intro/elim/dest attributes: changed

intro/intro!/intro!!  flags to intro!/intro/intro? (in most cases, one

should have to change intro!! to intro? only);

* Provers: strengthened force_tac by using new first_best_tac;

* Provers: Blast_tac now warns of and ignores "weak elimination rules" e.g.

  [| inj ?f;          ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W

use instead the strong form,

  [| inj ?f; ~ ?W ==> ?f ?x = ?f ?y; ?x = ?y ==> ?W |] ==> ?W

In HOL, FOL and ZF the function cla_make_elim will create such rules

from destruct-rules;

* Provers: safe_asm_full_simp_tac is no longer in the simplifier signature. Use

  val safe_asm_full_simp_tac = generic_simp_tac true (true,true,true);

  if required.

* ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global

timing flag supersedes proof_timing and Toplevel.trace;

* ML: PureThy.add_thms/add_axioms/add_defs return theorems as well;

* ML: PureThy.add_defs gets additional argument to indicate potential

overloading (usually false);

* LaTeX: several changes of isabelle.sty;

*** Document preparation ***

* formal comments (text blocks etc.) in new-style theories may now

contain antiquotations of thm/prop/term/typ to be presented according

to latex print mode; concrete syntax is like this: @{term[show_types]

"f(x) = a + x"};

* isatool mkdir provides easy setup of Isabelle session directories,

including proper document sources;

* generated LaTeX sources are now deleted after successful run

(isatool document -c); may retain a copy somewhere else via -D option

of isatool usedir;

* isatool usedir -D now lets isatool latex -o sty update the Isabelle

style files, achieving self-contained LaTeX sources;

* old-style theories now produce (crude) LaTeX output as well;

* browser info session directories are now self-contained (may be put

on WWW server seperately); improved graphs of nested sessions; removed

graph for 'all sessions';

*** Isar ***

* Pure: local results and corresponding term bindings are now subject

to Hindley-Milner polymorphism (similar to ML); this accommodates

incremental type-inference nicely;

* Pure: new 'obtain' language element supports generalized existence

reasoning;

* Pure: new calculational elements 'moreover' and 'ultimately' support

plain accumulation of results, without applying any rules yet;

* Pure: scalable support for case-analysis type proofs: new 'case'

language element refers to local contexts symbolically, as produced by

certain proof methods; internally, case names are attached to theorems

as "tags";

* Pure: theory command 'hide' removes declarations from

class/type/const name spaces;

* Pure: theory command 'defs' supports option "(overloaded)" to

indicate potential overloading;

* Pure: changed syntax of local blocks from {{ }} to { };

* Pure: syntax of sorts made inner, i.e. have to write "{a, b, c}"

instead of {a, b, c};

* Pure now provides its own version of intro/elim/dest attributes;

useful for building new logics, but beware of confusion with the

Provers/classical ones;

* Pure: the local context of (non-atomic) goals is provided via case

name 'antecedent';

* Pure: removed obsolete 'transfer' attribute (transfer of thms to the

current context is now done automatically);

* Pure: theory command 'method_setup' provides a simple interface for

definining proof methods in ML;

* Provers: splitter support (via 'split' attribute and 'simp' method

modifier); 'simp' method: 'only:' modifier removes loopers as well

(including splits);

* HOL: new proof method 'cases' and improved version of 'induct' now

support named cases; major packages (inductive, datatype, primrec,

recdef) support case names and properly name parameters;

* HOL: removed 'case_split' thm binding, should use 'cases' proof

method anyway;

* HOL/Calculation: new rules for substitution in inequalities

(monotonicity conditions are extracted to be proven terminally);

* HOL: removed obsolete expand_if = split_if; theorems if_splits =

split_if split_if_asm; datatype package provides theorems foo.splits =

foo.split foo.split_asm for each datatype;

* names of theorems etc. may be natural numbers as well;

* Provers: intro/elim/dest attributes: changed intro/intro!/intro!!

flags to intro!/intro/intro? (in most cases, one should have to change

intro!! to intro? only);

* 'pr' command: optional goals_limit argument; no longer prints theory

contexts, but only proof states;

* diagnostic commands 'pr', 'thm', 'prop', 'term', 'typ' admit

additional print modes to be specified; e.g. "pr(latex)" will print

proof state according to the Isabelle LaTeX style;

* improved support for emulating tactic scripts, including proof

methods 'tactic', 'res_inst_tac' etc., 'subgoal_tac', and 'case_tac' /

'induct_tac' (for HOL datatypes);

* simplified (more robust) goal selection of proof methods: 1st goal,

all goals, or explicit goal specifier (tactic emulation); thus 'proof

method scripts' have to be in depth-first order;

* tuned 'let' syntax: replaced 'as' keyword by 'and';

* removed 'help' command, which hasn't been too helpful anyway; should

instead use individual commands for printing items (print_commands,

print_methods etc.);

* added 'nothing' --- the empty list of theorems;

*** HOL ***

* HOL/Prolog: a (bare-bones) implementation of Lambda-Prolog

* HOL/Algebra: new theory of rings and univariate polynomials, by

Clemens Ballarin;

* HOL/record: fixed select-update simplification procedure to handle

extended records as well; admit "r" as field name;

* HOL/ex: new theory Factorization proving the Fundamental Theorem of

Arithmetic, by Thomas M Rasmussen;

* HOL/ex/Multiquote: multiple nested quotations and anti-quotations --

basically a generalized version of de-Bruijn representation; very

useful in avoiding lifting all operations;

* HOL/Real: "rabs" replaced by overloaded "abs" function;

* HOL: 0 is now overloaded over the new sort "zero", allowing its use with

other numeric types and also as the identity of groups, rings, etc.;

* HOL: new axclass plus_ac0 for addition with the AC-laws and 0 as identity.

Types nat and int belong to this axclass;

* greatly improved simplification involving numerals of type nat, int, real:

   (i + #8 + j) = Suc k simplifies to  #7 + (i + j) = k

   i*j + k + j*#3*i     simplifies to  #4*(i*j) + k

  two terms #m*u and #n*u are replaced by #(m+n)*u

    (where #m, #n and u can implicitly be 1; this is simproc combine_numerals)

  and the term/formula #m*u+x ~~ #n*u+y simplifies simplifies to #(m-n)+x ~~ y

    or x ~~ #(n-m)+y, where ~~ is one of = < <= or - (simproc cancel_numerals);

* HOL: new version of "case_tac" subsumes both boolean case split and

"exhaust_tac" on datatypes; INCOMPATIBILITY: exhaust_tac no longer

exists, may define val exhaust_tac = case_tac for ad-hoc portability;

* HOL: simplification no longer dives into case-expressions: only the

selector expression is simplified, but not the remaining arms. To

enable full simplification of case-expressions for datatype t, you

need to remove t.weak_case_cong from the simpset, either permanently

(Delcongs[thm"t.weak_case_cong"];) or locally (delcongs [...]).

* HOL/recdef: the recursion equations generated by 'recdef' for

function 'f' are now called f.simps instead of f.rules; if all

termination conditions are proved automatically, these simplification

rules are added to the simpset, as in primrec; rules may be named

individually as well, resulting in a separate list of theorems for

each equation;

* HOL/While is a new theory that provides a while-combinator. It permits the

definition of tail-recursive functions without the provision of a termination

measure. The latter is necessary once the invariant proof rule for while is

applied.

* HOL: new (overloaded) notation for the set of elements below/above some

element: {..u}, {..u(}, {l..}, {)l..}. See theory SetInterval.

* HOL: theorems impI, allI, ballI bound as "strip";

* theory Sexp now in HOL/Induct examples (used to be part of main HOL,

but was unused);

* fewer consts declared as global (e.g. have to refer to "Lfp.lfp"

instead of "lfp" internally; affects ML packages only);

* tuned AST representation of nested pairs, avoiding bogus output in

case of overlap with user translations (e.g. judgements over tuples);

*** FOL & ZF ***

* AddIffs now available, giving theorems of the form P<->Q to the

  simplifier and classical reasoner simultaneously;

*** General ***

* AST translation rules no longer require constant head on LHS;

* improved name spaces: ambiguous output is qualified; support for

hiding of names;

* compression of ML heaps images may now be controlled via -c option

of isabelle and isatool usedir (currently only observed by Poly/ML);

* provide TAGS file for Isabelle sources;

* ML: infix 'OF' is a version of 'MRS' with more appropriate argument

order;

* ML: renamed flags Syntax.trace_norm_ast to Syntax.trace_ast; global

timing flag supersedes proof_timing and Toplevel.trace;

* ML: PureThy.add_defs gets additional argument to indicate potential

overloading (usually false);

* ML: new combinators |>> and |>>> for incremental transformations

with secondary results (e.g. certain theory extensions):

New in Isabelle99 (October 1999)

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

*** Overview of INCOMPATIBILITIES (see below for more details) ***

* HOL: The THEN and ELSE parts of conditional expressions (if P then x else y)

are no longer simplified.  (This allows the simplifier to unfold recursive

functional programs.)  To restore the old behaviour, declare

    Delcongs [if_weak_cong];

* HOL: Removed the obsolete syntax "Compl A"; use -A for set

complement;

* HOL: the predicate "inj" is now defined by translation to "inj_on";

* HOL/datatype: mutual_induct_tac no longer exists --

  use induct_tac "x_1 ... x_n" instead of mutual_induct_tac ["x_1", ..., "x_n"]

* HOL/typedef: fixed type inference for representing set; type

arguments now have to occur explicitly on the rhs as type constraints;

* ZF: The con_defs part of an inductive definition may no longer refer

to constants declared in the same theory;

* HOL, ZF: the function mk_cases, generated by the inductive

definition package, has lost an argument.  To simplify its result, it

uses the default simpset instead of a supplied list of theorems.

* HOL/List: the constructors of type list are now Nil and Cons;

* Simplifier: the type of the infix ML functions

        setSSolver addSSolver setSolver addSolver

is now  simpset * solver -> simpset  where `solver' is a new abstract type

for packaging solvers. A solver is created via

        mk_solver: string -> (thm list -> int -> tactic) -> solver

where the string argument is only a comment.

*** Proof tools ***

* Provers/Arith/fast_lin_arith.ML contains a functor for creating a

decision procedure for linear arithmetic. Currently it is used for

types `nat', `int', and `real' in HOL (see below); it can, should and

will be instantiated for other types and logics as well.

* The simplifier now accepts rewrite rules with flexible heads, eg

     hom ?f ==> ?f(?x+?y) = ?f ?x + ?f ?y

  They are applied like any rule with a non-pattern lhs, i.e. by first-order

  matching.

*** General ***

* New Isabelle/Isar subsystem provides an alternative to traditional

tactical theorem proving; together with the ProofGeneral/isar user

interface it offers an interactive environment for developing human

readable proof documents (Isar == Intelligible semi-automated

reasoning); for further information see isatool doc isar-ref,

src/HOL/Isar_examples and http://isabelle.in.tum.de/Isar/

* improved presentation of theories: better HTML markup (including

colors), graph views in several sizes; isatool usedir now provides a

proper interface for user theories (via -P option); actual document

preparation based on (PDF)LaTeX is available as well (for new-style

theories only); see isatool doc system for more information;

* native support for Proof General, both for classic Isabelle and

Isabelle/Isar;

* ML function thm_deps visualizes dependencies of theorems and lemmas,

using the graph browser tool;

* Isabelle manuals now also available as PDF;

* theory loader rewritten from scratch (may not be fully

bug-compatible); old loadpath variable has been replaced by show_path,

add_path, del_path, reset_path functions; new operations such as

update_thy, touch_thy, remove_thy, use/update_thy_only (see also

isatool doc ref);

* improved isatool install: option -k creates KDE application icon,

option -p DIR installs standalone binaries;

* added ML_PLATFORM setting (useful for cross-platform installations);

more robust handling of platform specific ML images for SML/NJ;

* the settings environment is now statically scoped, i.e. it is never

created again in sub-processes invoked from isabelle, isatool, or

Isabelle;

* path element specification '~~' refers to '$ISABELLE_HOME';

* in locales, the "assumes" and "defines" parts may be omitted if

empty;

* new print_mode "xsymbols" for extended symbol support (e.g. genuine

long arrows);

* new print_mode "HTML";

* new flag show_tags controls display of tags of theorems (which are

basically just comments that may be attached by some tools);

* Isamode 2.6 requires patch to accomodate change of Isabelle font

mode and goal output format:

diff -r Isamode-2.6/elisp/isa-load.el Isamode/elisp/isa-load.el

244c244

<       (list (isa-getenv "ISABELLE") "-msymbols" logic-name)

---

>       (list (isa-getenv "ISABELLE") "-misabelle_font" "-msymbols" logic-name)

diff -r Isabelle-2.6/elisp/isa-proofstate.el Isamode/elisp/isa-proofstate.el

181c181

< (defconst proofstate-proofstart-regexp "^Level [0-9]+$"

---

> (defconst proofstate-proofstart-regexp "^Level [0-9]+"

* function bind_thms stores lists of theorems (cf. bind_thm);

* new shorthand tactics ftac, eatac, datac, fatac;

* qed (and friends) now accept "" as result name; in that case the

theorem is not stored, but proper checks and presentation of the

result still apply;

* theorem database now also indexes constants "Trueprop", "all",

"==>", "=="; thus thms_containing, findI etc. may retrieve more rules;

*** HOL ***

** HOL arithmetic **

* There are now decision procedures for linear arithmetic over nat and

int:

1. arith_tac copes with arbitrary formulae involving `=', `<', `<=',

`+', `-', `Suc', `min', `max' and numerical constants; other subterms

are treated as atomic; subformulae not involving type `nat' or `int'

are ignored; quantified subformulae are ignored unless they are

positive universal or negative existential. The tactic has to be

invoked by hand and can be a little bit slow. In particular, the

running time is exponential in the number of occurrences of `min' and

`max', and `-' on `nat'.

2. fast_arith_tac is a cut-down version of arith_tac: it only takes

(negated) (in)equalities among the premises and the conclusion into

account (i.e. no compound formulae) and does not know about `min' and

`max', and `-' on `nat'. It is fast and is used automatically by the

simplifier.

NB: At the moment, these decision procedures do not cope with mixed

nat/int formulae where the two parts interact, such as `m < n ==>

int(m) < int(n)'.

* HOL/Numeral provides a generic theory of numerals (encoded

efficiently as bit strings); setup for types nat/int/real is in place;

INCOMPATIBILITY: since numeral syntax is now polymorphic, rather than

int, existing theories and proof scripts may require a few additional

type constraints;

* integer division and remainder can now be performed on constant

arguments;

* many properties of integer multiplication, division and remainder

are now available;

* An interface to the Stanford Validity Checker (SVC) is available through the

tactic svc_tac.  Propositional tautologies and theorems of linear arithmetic

are proved automatically.  SVC must be installed separately, and its results

must be TAKEN ON TRUST (Isabelle does not check the proofs, but tags any

invocation of the underlying oracle).  For SVC see

  http://verify.stanford.edu/SVC

* IsaMakefile: the HOL-Real target now builds an actual image;

** HOL misc **

* HOL/Real/HahnBanach: the Hahn-Banach theorem for real vector spaces

(in Isabelle/Isar) -- by Gertrud Bauer;

* HOL/BCV: generic model of bytecode verification, i.e. data-flow

analysis for assembly languages with subtypes;

* HOL/TLA (Lamport's Temporal Logic of Actions): major reorganization

-- avoids syntactic ambiguities and treats state, transition, and

temporal levels more uniformly; introduces INCOMPATIBILITIES due to

changed syntax and (many) tactics;

* HOL/inductive: Now also handles more general introduction rules such

  as "ALL y. (y, x) : r --> y : acc r ==> x : acc r"; monotonicity

  theorems are now maintained within the theory (maintained via the

  "mono" attribute);

* HOL/datatype: Now also handles arbitrarily branching datatypes

  (using function types) such as

  datatype 'a tree = Atom 'a | Branch "nat => 'a tree"

* HOL/record: record_simproc (part of the default simpset) takes care

of selectors applied to updated records; record_split_tac is no longer

part of the default claset; update_defs may now be removed from the

simpset in many cases; COMPATIBILITY: old behavior achieved by

  claset_ref () := claset() addSWrapper record_split_wrapper;

  Delsimprocs [record_simproc]

* HOL/typedef: fixed type inference for representing set; type

arguments now have to occur explicitly on the rhs as type constraints;

* HOL/recdef (TFL): 'congs' syntax now expects comma separated list of theorem

names rather than an ML expression;

* HOL/defer_recdef (TFL): like recdef but the well-founded relation can be

supplied later.  Program schemes can be defined, such as

    "While B C s = (if B s then While B C (C s) else s)"

where the well-founded relation can be chosen after B and C have been given.

* HOL/List: the constructors of type list are now Nil and Cons;

INCOMPATIBILITY: while [] and infix # syntax is still there, of

course, ML tools referring to List.list.op # etc. have to be adapted;

* HOL_quantifiers flag superseded by "HOL" print mode, which is

disabled by default; run isabelle with option -m HOL to get back to

the original Gordon/HOL-style output;

* HOL/Ord.thy: new bounded quantifier syntax (input only): ALL x<y. P,

ALL x<=y. P, EX x<y. P, EX x<=y. P;

* HOL basic syntax simplified (more orthogonal): all variants of

All/Ex now support plain / symbolic / HOL notation; plain syntax for

Eps operator is provided as well: "SOME x. P[x]";

* HOL/Sum.thy: sum_case has been moved to HOL/Datatype;

* HOL/Univ.thy: infix syntax <*>, <+>, <**>, <+> eliminated and made

thus available for user theories;

* HOLCF/IOA/Sequents: renamed 'Cons' to 'Consq' to avoid clash with

HOL/List; hardly an INCOMPATIBILITY since '>>' syntax is used all the

time;

* HOL: new tactic smp_tac: int -> int -> tactic, which applies spec

several times and then mp;

*** LK ***

* the notation <<...>> is now available as a notation for sequences of

formulas;

* the simplifier is now installed

* the axiom system has been generalized (thanks to Soren Heilmann)

* the classical reasoner now has a default rule database

*** ZF ***

* new primrec section allows primitive recursive functions to be given

directly (as in HOL) over datatypes and the natural numbers;

* new tactics induct_tac and exhaust_tac for induction (or case

analysis) over datatypes and the natural numbers;

* the datatype declaration of type T now defines the recursor T_rec;

* simplification automatically does freeness reasoning for datatype

constructors;

* automatic type-inference, with AddTCs command to insert new

type-checking rules;

* datatype introduction rules are now added as Safe Introduction rules

to the claset;

* the syntax "if P then x else y" is now available in addition to

if(P,x,y);

*** Internal programming interfaces ***

* tuned simplifier trace output; new flag debug_simp;

* structures Vartab / Termtab (instances of TableFun) offer efficient

tables indexed by indexname_ord / term_ord (compatible with aconv);

* AxClass.axclass_tac lost the theory argument;

* tuned current_goals_markers semantics: begin / end goal avoids

printing empty lines;

* removed prs and prs_fn hook, which was broken because it did not

include \n in its semantics, forcing writeln to add one

uncoditionally; replaced prs_fn by writeln_fn; consider std_output:

string -> unit if you really want to output text without newline;

* Symbol.output subject to print mode; INCOMPATIBILITY: defaults to

plain output, interface builders may have to enable 'isabelle_font'

mode to get Isabelle font glyphs as before;

* refined token_translation interface; INCOMPATIBILITY: output length

now of type real instead of int;

* theory loader actions may be traced via new ThyInfo.add_hook

interface (see src/Pure/Thy/thy_info.ML); example application: keep

your own database of information attached to *whole* theories -- as

opposed to intra-theory data slots offered via TheoryDataFun;

* proper handling of dangling sort hypotheses (at last!);

Thm.strip_shyps and Drule.strip_shyps_warning take care of removing

extra sort hypotheses that can be witnessed from the type signature;

the force_strip_shyps flag is gone, any remaining shyps are simply

left in the theorem (with a warning issued by strip_shyps_warning);

New in Isabelle98-1 (October 1998)

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

*** Overview of INCOMPATIBILITIES (see below for more details) ***

* several changes of automated proof tools;

* HOL: major changes to the inductive and datatype packages, including

some minor incompatibilities of theory syntax;

* HOL: renamed r^-1 to 'converse' from 'inverse'; 'inj_onto' is now

called `inj_on';

* HOL: removed duplicate thms in Arith:

  less_imp_add_less  should be replaced by  trans_less_add1

  le_imp_add_le      should be replaced by  trans_le_add1

* HOL: unary minus is now overloaded (new type constraints may be

required);

* HOL and ZF: unary minus for integers is now #- instead of #~.  In

ZF, expressions such as n#-1 must be changed to n#- 1, since #-1 is

now taken as an integer constant.

* Pure: ML function 'theory_of' renamed to 'theory';

*** Proof tools ***

* Simplifier:

  1. Asm_full_simp_tac is now more aggressive.

     1. It will sometimes reorient premises if that increases their power to

        simplify.

     2. It does no longer proceed strictly from left to right but may also

        rotate premises to achieve further simplification.

     For compatibility reasons there is now Asm_lr_simp_tac which is like the

     old Asm_full_simp_tac in that it does not rotate premises.

  2. The simplifier now knows a little bit about nat-arithmetic.

* Classical reasoner: wrapper mechanism for the classical reasoner now

allows for selected deletion of wrappers, by introduction of names for

wrapper functionals.  This implies that addbefore, addSbefore,

addaltern, and addSaltern now take a pair (name, tactic) as argument,

and that adding two tactics with the same name overwrites the first

one (emitting a warning).

  type wrapper = (int -> tactic) -> (int -> tactic)

  setWrapper, setSWrapper, compWrapper and compSWrapper are replaced by

  addWrapper, addSWrapper: claset * (string * wrapper) -> claset

  delWrapper, delSWrapper: claset *  string            -> claset

  getWrapper is renamed to appWrappers, getSWrapper to appSWrappers;

* Classical reasoner: addbefore/addSbefore now have APPEND/ORELSE

semantics; addbefore now affects only the unsafe part of step_tac

etc.; this affects addss/auto_tac/force_tac, so EXISTING PROOFS MAY

FAIL, but proofs should be fixable easily, e.g. by replacing Auto_tac

by Force_tac;

* Classical reasoner: setwrapper to setWrapper and compwrapper to

compWrapper; added safe wrapper (and access functions for it);

* HOL/split_all_tac is now much faster and fails if there is nothing

to split.  Some EXISTING PROOFS MAY REQUIRE ADAPTION because the order

and the names of the automatically generated variables have changed.

split_all_tac has moved within claset() from unsafe wrappers to safe

wrappers, which means that !!-bound variables are split much more

aggressively, and safe_tac and clarify_tac now split such variables.

If this splitting is not appropriate, use delSWrapper "split_all_tac".

Note: the same holds for record_split_tac, which does the job of

split_all_tac for record fields.

* HOL/Simplifier: Rewrite rules for case distinctions can now be added

permanently to the default simpset using Addsplits just like

Addsimps. They can be removed via Delsplits just like

Delsimps. Lower-case versions are also available.

* HOL/Simplifier: The rule split_if is now part of the default

simpset. This means that the simplifier will eliminate all occurrences

of if-then-else in the conclusion of a goal. To prevent this, you can

either remove split_if completely from the default simpset by

`Delsplits [split_if]' or remove it in a specific call of the

simplifier using `... delsplits [split_if]'.  You can also add/delete

other case splitting rules to/from the default simpset: every datatype

generates suitable rules `split_t_case' and `split_t_case_asm' (where

t is the name of the datatype).

* Classical reasoner / Simplifier combination: new force_tac (and

derivatives Force_tac, force) combines rewriting and classical

reasoning (and whatever other tools) similarly to auto_tac, but is

aimed to solve the given subgoal completely.

*** General ***

* new top-level commands `Goal' and `Goalw' that improve upon `goal'

and `goalw': the theory is no longer needed as an explicit argument -

the current theory context is used; assumptions are no longer returned

at the ML-level unless one of them starts with ==> or !!; it is

recommended to convert to these new commands using isatool fixgoal

(backup your sources first!);

* new top-level commands 'thm' and 'thms' for retrieving theorems from

the current theory context, and 'theory' to lookup stored theories;

* new theory section 'locale' for declaring constants, assumptions and

definitions that have local scope;

* new theory section 'nonterminals' for purely syntactic types;

* new theory section 'setup' for generic ML setup functions

(e.g. package initialization);

* the distribution now includes Isabelle icons: see

lib/logo/isabelle-{small,tiny}.xpm;

* isatool install - install binaries with absolute references to

ISABELLE_HOME/bin;

* isatool logo -- create instances of the Isabelle logo (as EPS);

* print mode 'emacs' reserved for Isamode;

* support multiple print (ast) translations per constant name;

* theorems involving oracles are now printed with a suffixed [!];

*** HOL ***

* there is now a tutorial on Isabelle/HOL (do 'isatool doc tutorial');

* HOL/inductive package reorganized and improved: now supports mutual

definitions such as

  inductive EVEN ODD

    intrs

      null "0 : EVEN"

      oddI "n : EVEN ==> Suc n : ODD"

      evenI "n : ODD ==> Suc n : EVEN"

new theorem list "elims" contains an elimination rule for each of the

recursive sets; inductive definitions now handle disjunctive premises

correctly (also ZF);

INCOMPATIBILITIES: requires Inductive as an ancestor; component

"mutual_induct" no longer exists - the induction rule is always

contained in "induct";

* HOL/datatype package re-implemented and greatly improved: now

supports mutually recursive datatypes such as

  datatype

    'a aexp = IF_THEN_ELSE ('a bexp) ('a aexp) ('a aexp)

            | SUM ('a aexp) ('a aexp)

            | DIFF ('a aexp) ('a aexp)

            | NUM 'a

  and

    'a bexp = LESS ('a aexp) ('a aexp)

            | AND ('a bexp) ('a bexp)

            | OR ('a bexp) ('a bexp)

as well as indirectly recursive datatypes such as

  datatype

    ('a, 'b) term = Var 'a

                  | App 'b ((('a, 'b) term) list)

The new tactic  mutual_induct_tac [<var_1>, ..., <var_n>] i  performs

induction on mutually / indirectly recursive datatypes.

Primrec equations are now stored in theory and can be accessed via

<function_name>.simps.

INCOMPATIBILITIES:

  - Theories using datatypes must now have theory Datatype as an

    ancestor.

  - The specific <typename>.induct_tac no longer exists - use the

    generic induct_tac instead.

  - natE has been renamed to nat.exhaust - use exhaust_tac

    instead of res_inst_tac ... natE. Note that the variable

    names in nat.exhaust differ from the names in natE, this

    may cause some "fragile" proofs to fail.

  - The theorems split_<typename>_case and split_<typename>_case_asm

    have been renamed to <typename>.split and <typename>.split_asm.

  - Since default sorts of type variables are now handled correctly,

    some datatype definitions may have to be annotated with explicit

    sort constraints.

  - Primrec definitions no longer require function name and type

    of recursive argument.

Consider using isatool fixdatatype to adapt your theories and proof

scripts to the new package (backup your sources first!).

* HOL/record package: considerably improved implementation; now

includes concrete syntax for record types, terms, updates; theorems

for surjective pairing and splitting !!-bound record variables; proof

support is as follows:

  1) standard conversions (selectors or updates applied to record

constructor terms) are part of the standard simpset;

  2) inject equations of the form ((x, y) = (x', y')) == x=x' & y=y' are

made part of standard simpset and claset via addIffs;

  3) a tactic for record field splitting (record_split_tac) is part of

the standard claset (addSWrapper);

To get a better idea about these rules you may retrieve them via

something like 'thms "foo.simps"' or 'thms "foo.iffs"', where "foo" is

the name of your record type.

The split tactic 3) conceptually simplifies by the following rule:

  "(!!x. PROP ?P x) == (!!a b. PROP ?P (a, b))"

Thus any record variable that is bound by meta-all will automatically

blow up into some record constructor term, consequently the

simplifications of 1), 2) apply.  Thus force_tac, auto_tac etc. shall

solve record problems automatically.

* reorganized the main HOL image: HOL/Integ and String loaded by

default; theory Main includes everything;

* automatic simplification of integer sums and comparisons, using cancellation;

* added option_map_eq_Some and not_Some_eq to the default simpset and claset;

* added disj_not1 = "(~P | Q) = (P --> Q)" to the default simpset;

* many new identities for unions, intersections, set difference, etc.;

* expand_if, expand_split, expand_sum_case and expand_nat_case are now

called split_if, split_split, split_sum_case and split_nat_case (to go

with add/delsplits);

* HOL/Prod introduces simplification procedure unit_eq_proc rewriting

(?x::unit) = (); this is made part of the default simpset, which COULD

MAKE EXISTING PROOFS FAIL under rare circumstances (consider

'Delsimprocs [unit_eq_proc];' as last resort); also note that

unit_abs_eta_conv is added in order to counter the effect of

unit_eq_proc on (%u::unit. f u), replacing it by f rather than by

%u.f();

* HOL/Fun INCOMPATIBILITY: `inj_onto' is now called `inj_on' (which

makes more sense);

* HOL/Set INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;

  It and 'sym RS equals0D' are now in the default  claset, giving automatic

  disjointness reasoning but breaking a few old proofs.

* HOL/Relation INCOMPATIBILITY: renamed the relational operator r^-1

to 'converse' from 'inverse' (for compatibility with ZF and some

literature);

* HOL/recdef can now declare non-recursive functions, with {} supplied as

the well-founded relation;

* HOL/Set INCOMPATIBILITY: the complement of set A is now written -A instead of

    Compl A.  The "Compl" syntax remains available as input syntax for this

    release ONLY.

* HOL/Update: new theory of function updates:

    f(a:=b) == %x. if x=a then b else f x

may also be iterated as in f(a:=b,c:=d,...);

* HOL/Vimage: new theory for inverse image of a function, syntax f-``B;

* HOL/List:

  - new function list_update written xs[i:=v] that updates the i-th

    list position. May also be iterated as in xs[i:=a,j:=b,...].

  - new function `upt' written [i..j(] which generates the list

    [i,i+1,...,j-1], i.e. the upper bound is excluded. To include the upper

    bound write [i..j], which is a shorthand for [i..j+1(].

  - new lexicographic orderings and corresponding wellfoundedness theorems.

* HOL/Arith:

  - removed 'pred' (predecessor) function;

  - generalized some theorems about n-1;

  - many new laws about "div" and "mod";

  - new laws about greatest common divisors (see theory ex/Primes);

* HOL/Relation: renamed the relational operator r^-1 "converse"

instead of "inverse";

* HOL/Induct/Multiset: a theory of multisets, including the wellfoundedness

  of the multiset ordering;

* directory HOL/Real: a construction of the reals using Dedekind cuts

  (not included by default);

* directory HOL/UNITY: Chandy and Misra's UNITY formalism;

* directory HOL/Hoare: a new version of Hoare logic which permits many-sorted

  programs, i.e. different program variables may have different types.

* calling (stac rew i) now fails if "rew" has no effect on the goal

  [previously, this check worked only if the rewrite rule was unconditional]

  Now rew can involve either definitions or equalities (either == or =).

*** ZF ***

* theory Main includes everything; INCOMPATIBILITY: theory ZF.thy contains

  only the theorems proved on ZF.ML;

* ZF INCOMPATIBILITY: rule `equals0D' is now a well-formed destruct rule;

  It and 'sym RS equals0D' are now in the default  claset, giving automatic

  disjointness reasoning but breaking a few old proofs.

* ZF/Update: new theory of function updates

    with default rewrite rule  f(x:=y) ` z = if(z=x, y, f`z)

  may also be iterated as in f(a:=b,c:=d,...);

* in  let x=t in u(x), neither t nor u(x) has to be an FOL term.

* calling (stac rew i) now fails if "rew" has no effect on the goal

  [previously, this check worked only if the rewrite rule was unconditional]

  Now rew can involve either definitions or equalities (either == or =).

* case_tac provided for compatibility with HOL

    (like the old excluded_middle_tac, but with subgoals swapped)

*** Internal programming interfaces ***

* Pure: several new basic modules made available for general use, see

also src/Pure/README;

* improved the theory data mechanism to support encapsulation (data

kind name replaced by private Object.kind, acting as authorization

key); new type-safe user interface via functor TheoryDataFun; generic

print_data function becomes basically useless;

* removed global_names compatibility flag -- all theory declarations

are qualified by default;

* module Pure/Syntax now offers quote / antiquote translation

functions (useful for Hoare logic etc. with implicit dependencies);

see HOL/ex/Antiquote for an example use;

* Simplifier now offers conversions (asm_)(full_)rewrite: simpset ->

cterm -> thm;

* new tactical CHANGED_GOAL for checking that a tactic modifies a

subgoal;

* Display.print_goals function moved to Locale.print_goals;

* standard print function for goals supports current_goals_markers

variable for marking begin of proof, end of proof, start of goal; the

default is ("", "", ""); setting current_goals_markers := ("<proof>",

"</proof>", "<goal>") causes SGML like tagged proof state printing,

for example;

New in Isabelle98 (January 1998)

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

*** Overview of INCOMPATIBILITIES (see below for more details) ***

* changed lexical syntax of terms / types: dots made part of long

identifiers, e.g. "%x.x" no longer possible, should be "%x. x";

* simpset (and claset) reference variable replaced by functions

simpset / simpset_ref;

* no longer supports theory aliases (via merge) and non-trivial

implicit merge of thms' signatures;

* most internal names of constants changed due to qualified names;

* changed Pure/Sequence interface (see Pure/seq.ML);

*** General Changes ***

* hierachically structured name spaces (for consts, types, axms, thms

etc.); new lexical class 'longid' (e.g. Foo.bar.x) may render much of