unfold nsearch_spec in |- *.
intros goal work ds ni ai a context in_ngamma complete sound mon.
apply NSearch_Res with ni; try assumption.
apply le_ni_refl.
apply NDerivable.
apply sound with (c := NAtom goal); assumption.
Qed.
(**********************************************************************)

(* Specifications: *)
Lemma nefq :
forall (goal : Int) (work : nf_list) (ds : disjs)
(ni : nested_imps) (ai : atomic_imps) (a : atoms)
(context : flist), nsearch_spec goal (NFalsum :: work) ds ni ai a context.