proposition: Lemma lagrangeE i : lagrange_ i = lagrange_def i :> {poly _}.
proof: Proof. rewrite [lagrange]unlock tnth_map. by rewrite [val _]npolypK tnth_ord_tuple // size_lagrange_def. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice fintype tuple) mathcomp(bigop binomial finset finfun ssralg countalg finalg poly polydiv) mathcomp(perm fingroup matrix mxalgebra mxpoly vector countalg)