proposition: Lemma umfoldlPt a (z0 d : R) k v : um_foldl a z0 d (pts k v) = if C k then a z0 k v else d.
proof: Proof. by rewrite /um_foldl 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)