NEWS

*** empty log message ***

Isabelle NEWS -- history of user-visible changes
================================================


New in Isabelle94-8 (??????????? 1997 FIXME)
---------------------------------------

* the NEWS file;

* new utilities to build / run / maintain Isabelle etc. (in parts
still somewhat experimental); old Makefiles etc. still functional;

* simplifier: termless order as parameter; added interface for
simplification procedures (functions that produce *proven* rewrite
rules on the fly, depending on current redex);

* now supports alternative (named) syntax tables (parser and pretty
printer); internal interface is provided by add_modesyntax(_i);

* Pure, FOL, ZF, HOL, HOLCF now support symbolic input and output; to
be used in conjunction with the isabelle symbol font; uses the
"symbols" syntax table;

* infixes may now be declared with names independent of their syntax;

* added typed_print_translation (like print_translation, but may
access type of constant);

* prlim command for dealing with lots of subgoals (an easier way of
setting goals_limit);

* HOL/ex/Ring.thy declares cring_simp, which solves equational
problems in commutative rings, using axiomatic type classes for + and *;

* ZF now has Fast_tac, Simp_tac and Auto_tac.  WARNING: don't use
ZF.thy anymore!  Contains fewer defs and could make a bogus simpset.
Beware of Union_iff.  eq_cs is gone, can be put back as ZF_cs addSIs
[equalityI];

* more examples in HOL/MiniML and HOL/Auth;

* more default rewrite rules in HOL for quantifiers, union/intersection;



New in Isabelle94-7 (November 96)
---------------------------------

* allowing negative levels (as offsets) in prlev and choplev;

* super-linear speedup for large simplifications;

* FOL, ZF and HOL now use miniscoping: rewriting pushes
quantifications in as far as possible (COULD MAKE EXISTING PROOFS
FAIL); can suppress it using the command Delsimps (ex_simps @
all_simps); De Morgan laws are also now included, by default;

* improved printing of ==>  :  ~:

* new object-logic "Sequents" adds linear logic, while replacing LK
and Modal (thanks to Sara Kalvala);

* HOL/Auth: correctness proofs for authentication protocols;

* HOL: new auto_tac combines rewriting and classical reasoning (many
examples on HOL/Auth);

* HOL: new command AddIffs for declaring theorems of the form P=Q to
the rewriter and classical reasoner simultaneously;

* function uresult no longer returns theorems in "standard" format;
regain previous version by: val uresult = standard o uresult;



New in Isabelle94-6
-------------------

* oracles -- these establish an interface between Isabelle and trusted
external reasoners, which may deliver results as theorems;

* proof objects (in particular record all uses of oracles);

* Simp_tac, Fast_tac, etc. that refer to implicit simpset / claset;

* "constdefs" section in theory files;

* "primrec" section (HOL) no longer requires names;

* internal type "tactic" now simply "thm -> thm Sequence.seq";



New in Isabelle94-5
-------------------

* reduced space requirements;

* automatic HTML generation from theories;

* theory files no longer require "..." (quotes) around most types;

* new examples, including two proofs of the Church-Rosser theorem;

* non-curried (1994) version of HOL is no longer distributed;


$Id$