proposition: Lemma isog_pseries pis : G \isog H -> pseries pis G \isog pseries pis H.
proof: Proof. exact: gFisog. 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)