proposition: Lemma size_tail p k : size (tail k p) = size p - k.
proof: Proof. by rewrite /size /tail size_drop. Qed.
imports: Coq(ZArith Reals) Coquelicot(Coquelicot) mathcomp.ssreflect(ssreflect ssrfun ssrbool eqtype ssrnat seq fintype bigop) Flocq(Core) Stdlib MathComp Interval Xreal Basic_rec