intros a gamma work context minimal0.
unfold minimal in |- *.
intros b k k_is_mon k_forces_gamma in_b.
apply minimal0; try assumption.
apply forces_gamma_shift_work_gamma; assumption.
Qed.

Lemma minimal_shift_work_gamma :
forall (a : normal_form) (gamma : flist) (work : nf_list) (context : flist),
minimal gamma (a :: work) context ->
minimal (nf2form a :: gamma) work context.