--- /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 *)
+(* *)
+(**************************************************************************)
+
+set "baseuri" "cic:/matita/PREDICATIVE-TOPOLOGY/class_le".
+
+include "class_defs.ma".
+
+theorem cle_cl: \forall C,c1,c2. cle ? c1 c2 \to cin C c1 \land cin C c2.
+intros; elim H; clear H; clear c2;
+ [| decompose H2 ]; auto.
+qed.
+
+theorem cle_trans: \forall C,c1,c2. cle C c1 c2 \to
+ \forall c3. cle ? c3 c1 \to cle ? c3 c2.
+intros 4; elim H; clear H; clear c2;
+ [| apply ceq_sing; [||| apply H4 ]]; auto.
+qed.