proposition: Lemma injm_pseries pis G : G \subset D -> f @* pseries pis G = pseries pis (f @* G).
proof: Proof. exact: injmF. 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)