intros work ds ni1 ni2 ai a c le21 in_ngamma.
apply in_ngamma_eqv with ni1.
apply ge_eqv; assumption.
assumption.
Qed.
(***********************************************************************)
Inductive le_app_spec (ni1 : nested_imps) (n : nat) : Set :=
Le_App_Spec_Intro :
forall ni11 ni12 : nested_imps,
ni1 = ni11 ++ ni12 -> length ni11 = n -> le_app_spec ni1 n.

Lemma le_app0 :
forall ni1 ni21 ni22 : nested_imps,
le_ni ni1 (ni21 ++ ni22) -> le_app_spec ni1 (length ni21).