intros gamma work context a b forces_ba minimal0.
unfold minimal in |- *.
intros c k k_is_mon k_forces_gamma in_c.
apply minimal0; try assumption.
apply forces_gamma_cons_gamma_weak with b; try assumption.
intros; apply forces_ba; assumption.
Qed.

(* Specifications: *)
Lemma minimal_cons_gamma_weak2 :
forall (gamma : flist) (work : nf_list) (context : flist) (a b c : form),
(forall k : kripke_tree,
Is_Monotone_kripke_tree k -> forces_t k b -> forces_t k c -> forces_t k a) ->
minimal (a :: gamma) work context -> minimal (b :: c :: gamma) work context.