intros x work ds ni ai a context mon.
unfold nminimal in |- *.
intros c k k_is_mon k_forces_ngamma in_a.
apply mon; try assumption.
apply forces_ngamma_shift_ni_work; assumption.
Qed.

Lemma nminimal_shift_work_ai_new :
forall (i : Int) (b : normal_form) (work : nf_list)
(ds : disjs) (ni : nested_imps) (ai ai' : atomic_imps)
(a : atoms) (context : flist),
(forall bs : nf_list, LOOKUP nf_list i ai bs -> False) ->
EQUIV_INS nf_list i (cons b) nf_nil ai ai' ->
nminimal (AImp i b :: work) ds ni ai a context ->
nminimal work ds ni ai' a context.