proposition: Lemma umallUnR f1 f2 : valid (f1 \+ f2) -> um_all (f1 \+ f2) -> um_all f2.
proof: Proof. by rewrite joinC; apply: umallUnL. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)