Put in minimal simpset to avoid excessive simplification,
just as in revision 1.9 of HOL/indrule.ML
(* Title: HOLCF/ssum1.thy
ID: $Id$
Author: Franz Regensburger
Copyright 1993 Technische Universitaet Muenchen
Partial ordering for the strict sum ++
*)
Ssum1 = Ssum0 +
consts
less_ssum :: "[('a ++ 'b),('a ++ 'b)] => bool"
rules
less_ssum_def "less_ssum s1 s2 == (@z.
(! u x.s1=Isinl(u) & s2=Isinl(x) --> z = (u << x))
&(! v y.s1=Isinr(v) & s2=Isinr(y) --> z = (v << y))
&(! u y.s1=Isinl(u) & s2=Isinr(y) --> z = (u = UU))
&(! v x.s1=Isinr(v) & s2=Isinl(x) --> z = (v = UU)))"
end