proposition: Lemma SF_last_lx x0 (s : SF_seq) : fst (SF_last x0 s) = last 0 (SF_lx s).
proof: Proof. rewrite /SF_last /=. apply sym_eq ; by apply last_unzip1. Qed.
imports: Coq(Reals Psatz ssreflect ssrbool) mathcomp(seq) Rcomplements Rbar Lub Hierarchy