Section Basic.
Variable S : {group gT}.
Hypotheses (pS : p.-group S) (esS : extraspecial S).
Let pZ : p.-group 'Z(S) := pgroupS (center_sub S) pS.
End Basic.

Lemma injm_extraspecial D G (f : {morphism D >-> rT}) :
'injm f -> G \subset D -> extraspecial G -> extraspecial (f @* G).