proposition: Lemma umfoldrPt a (z0 d : R) k v : um_foldr a z0 d (pts k v) = if C k then a k v z0 else d.
proof: Proof. by rewrite /um_foldr validPt assocsPt; case: (C k). Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)