proposition: Lemma ftE (b : UM.base C V) : from (to b : U) = b.
proof: Proof. by case: U b =>x [*]. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)