(* Basic_2A1: uses: nta_fwd_csn *)
theorem nta_fwd_fsb (h) (a) (G) (L):
∀T,U. ❪G,L❫ ⊢ T :[h,a] U →
- ∧∧ ≥𝐒[h] ❪G,L,T❫ & ≥𝐒[h] ❪G,L,U❫.
+ ∧∧ ≥𝐒 ❪G,L,T❫ & ≥𝐒 ❪G,L,U❫.
#h #a #G #L #T #U #H
elim (cnv_inv_cast … H) #X #HU #HT #_ #_ -X
-/3 width=2 by cnv_fwd_fsb, conj/
+/3 width=3 by cnv_fwd_fsb, conj/
qed-.