added Pair_eq to pair_ss in prod.ML
removed it locally in llist.ML because preconditions of the form <a,b> =
<?x,?y>, which used to be solved by reflexivity, now rewrote to a = ?x & b =
?y, which is not solved by reflexivity.
(* Title: HOL/lfp.thy
ID: $Id$
Author: Lawrence C Paulson, Cambridge University Computer Laboratory
Copyright 1992 University of Cambridge
The Knaster-Tarski Theorem
*)
Lfp = Sum +
consts lfp :: "['a set=>'a set] => 'a set"
rules
(*least fixed point*)
lfp_def "lfp(f) == Inter({u. f(u) <= u})"
end