interpretation "stratified static type assignment (term)"
'StaticType h g l L T U = (ssta h g l L T U).
+definition ssta_step: ∀h. sd h → lenv → relation term ≝ λh,g,L,T,U.
+ ∃l. ⦃h, L⦄ ⊢ T •[g, l+1] U.
+
(* Basic inversion lemmas ************************************************)
fact ssta_inv_sort1_aux: ∀h,g,L,T,U,l. ⦃h, L⦄ ⊢ T •[g, l] U → ∀k0. T = ⋆k0 →