proposition: Lemma undefb0 : undefb (Unit : U) = false.
proof: Proof. by case: undefbP=>// /esym/undef0. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)