proposition: Lemma gacentE : 'C_(|to)(A) = 'Fix_(R | to)(A).
proof: Proof. by rewrite -{2}(setIidPr sAD). Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(fintype bigop finset fingroup morphism perm) mathcomp(automorphism quotient)