Section Homg.
Implicit Types rT gT aT : finGroupType.
Definition homg rT aT (C : {set rT}) (D : {set aT}) :=
[exists (f : {ffun aT -> rT} | morphic D f), f @: D == C].

Lemma morphim_homg aT rT (A D : {set aT}) (f : {morphism D >-> rT}) :
A \subset D -> homg (f @* A) A.