--- /dev/null
+(**************************************************************************)
+(* ___ *)
+(* ||M|| *)
+(* ||A|| A project by Andrea Asperti *)
+(* ||T|| *)
+(* ||I|| Developers: *)
+(* ||T|| The HELM team. *)
+(* ||A|| http://helm.cs.unibo.it *)
+(* \ / *)
+(* \ / This file is distributed under the terms of the *)
+(* v GNU General Public License Version 2 *)
+(* *)
+(**************************************************************************)
+
+include "basic_2/i_dynamic/ntas_preserve.ma".
+
+(* ITERATED NATIVE TYPE ASSIGNMENT FOR TERMS ********************************)
+
+(* Main properties **********************************************************)
+
+theorem ntas_trans (h) (a) (G) (L) (T0):
+ ∀n1,T1. ⦃G,L⦄ ⊢ T1 :*[h,a,n1] T0 →
+ ∀n2,T2. ⦃G,L⦄ ⊢ T0 :*[h,a,n2] T2 → ⦃G,L⦄ ⊢ T1 :*[h,a,n1+n2] T2.
+#h #a #G #L #T0 #n1 #T1 * #X1 #HT0 #HT1 #H01 #H11 #n2 #T2 * #X2 #HT2 #_ #H22 #H02
+elim (cnv_cpms_conf … HT0 … H01 … H02) -T0 <minus_O_n <minus_n_O #X0 #H10 #H20
+/3 width=5 by ntas_intro, cpms_trans/
+qed-.