proposition: Lemma constt_p_elt pi x : pi.-elt x -> x.`_pi = x.
proof: Proof. by rewrite -p_eltNK -{3}(consttC pi x) => /constt1P->; rewrite mulg1. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq div) mathcomp(fintype bigop finset prime fingroup morphism) mathcomp(gfunctor automorphism quotient action gproduct) mathcomp(cyclic)