proposition: Lemma um_unitbPt k v : unitb (pts k v : U) = false.
proof: Proof. by rewrite ptsU um_unitbU. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)