Variables (D : {group aT}) (f : {morphism D >-> rT}).

(* Specifications: *)
Lemma morphim_rank_abelian G : abelian G -> 'r(f @* G) <= 'r(G).
Lemma morphim_p_rank_abelian p G : abelian G -> 'r_p(f @* G) <= 'r_p(G).
Lemma isog_homocyclic G H : G \isog H -> homocyclic G = homocyclic H.
End IsogAbelian.