proposition: Lemma swapXY_Y : swapXY 'Y = 'X.
proof: Proof. by rewrite swapXY_polyC map_polyX. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype choice ssrnat seq) mathcomp(fintype tuple finfun bigop fingroup perm div) mathcomp(ssralg zmodp matrix mxalgebra) mathcomp(poly polydiv mxpoly binomial)