proposition: Lemma swapXY_eq0 u : (swapXY u == 0) = (u == 0).
proof: Proof. by rewrite (inv_eq swapXYK) raddf0. 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)