Section NormalComplement.
Variables K H G : {group gT}.
Hypothesis complH_K : H \in [complements to K in G].
End NormalComplement.
(* Semi-direct product *)

Lemma sdprod_context G K H : K ><| H = G ->
[/\ K <| G, H \subset G, K * H = G, H \subset 'N(K) & K :&: H = 1].