--- /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 "datatypes_defs/Sequent.ma".
+
+theorem linj_inj: \forall a,c. linj a = linj c \to a = c.
+ intros; whd in H:(? ? % %); destruct; autobatch.
+qed.
+
+theorem rinj_inj: \forall b,d. rinj b = rinj d \to b = d.
+ intros; whd in H:(? ? % %); destruct; autobatch.
+qed.