Modified proofs due to added triv_forall_equality.
Isabelle NEWS -- history of user-visible changes
================================================
New in Isabelle94-8 (??????????? 1997 FIXME)
---------------------------------------
* HOL: primrec now also works with type nat;
* 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;
* the NEWS file;
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;
New in Isabelle94-4
-------------------
* greatly space requirements;
* theory files (.thy) no longer require \...\ escapes at line breaks;
* searchable theorem database (see the section "Retrieving theorems" on
page 8 of the Reference Manual);
* new examples, including Grabczewski's monumental case study of the
Axiom of Choice;
* The previous version of HOL renamed to Old_HOL;
* The new version of HOL (previously called CHOL) uses a curried syntax
for functions. Application looks like f a b instead of f(a,b);
* Mutually recursive inductive definitions finally work in HOL;
* In ZF, pattern-matching on tuples is now available in all abstractions and
translates to the operator "split";
New in Isabelle94-3
-------------------
* new infix operator, addss, allowing the classical reasoner to
perform simplification at each step of its search. Example:
fast_tac (cs addss ss)
* a new logic, CHOL, the same as HOL, but with a curried syntax
for functions. Application looks like f a b instead of f(a,b). Also pairs
look like (a,b) instead of <a,b>;
* PLEASE NOTE: CHOL will eventually replace HOL!
* In CHOL, pattern-matching on tuples is now available in all abstractions.
It translates to the operator "split". A new theory of integers is available;
* In ZF, integer numerals now denote two's-complement binary integers.
Arithmetic operations can be performed by rewriting. See ZF/ex/Bin.ML;
* Many new examples: I/O automata, Church-Rosser theorem, equivalents
of the Axiom of Choice;
New in Isabelle94-2
-------------------
* Significantly faster resolution;
* the different sections in a .thy file can now be mixed and repeated
freely;
* Database of theorems for FOL, HOL and ZF. New
commands including qed, qed_goal and bind_thm store theorems in the database.
* Simple database queries: return a named theorem (get_thm) or all theorems of
a given theory (thms_of), or find out what theory a theorem was proved in
(theory_of_thm);
* Bugs fixed in the inductive definition and datatype packages;
* The classical reasoner provides deepen_tac and depth_tac, making FOL_dup_cs
and HOL_dup_cs obsolete;
* Syntactic ambiguities caused by the new treatment of syntax in Isabelle94-1
have been removed;
* Simpler definition of function space in ZF;
* new results about cardinal and ordinal arithmetic in ZF;
* 'subtype' facility in HOL for introducing new types as subsets of existing
types;
$Id$