HOL/subset.thy, equalities.thy, mono.thy: new
HOL/Lfp.thy: now depends upon mono
HOL/Gfp.thy: depends upon Lfp, not just mono
(* Title: Substitutions/setplus.thy
Author: Martin Coen, Cambridge University Computer Laboratory
Copyright 1993 University of Cambridge
Minor additions to HOL's set theory
*)
Setplus = Set +
rules
ssubset_def "A < B == A <= B & ~ A=B"
end