proposition: Lemma pseries_pop pi pis gT (G : {group gT}) : 'O_pi(G) = 1 -> pseries (pi :: pis) G = pseries pis G.
proof: Proof. by move=> OG1; rewrite /pseries rev_cons -cats1 foldr_cat /= pcore_mod1 OG1. 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)