proposition: Lemma centvC U V : (U <= 'C(V))%VS = (V <= 'C(U))%VS.
proof: Proof. by apply/centvsP/centvsP=> cUV u v UVu /cUV->. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(choice fintype div tuple finfun bigop ssralg) mathcomp(finalg zmodp matrix vector poly)