intros l i j below_l less_ij.
unfold below_list in |- *.
intros a in_a.
apply below_form_less_below_form with i.
apply below_l; assumption.
assumption.
Qed.

Lemma below_cons_list_head :
forall (a : form) (l : flist) (i : Int),
below_list (a :: l) i -> below_form a i.