proposition: Theorem interIncl1 : forall L1 L2 L3 : list A, inter L1 L2 L3 -> InclEq L3 L1.
proof: Proof. intros L1 L2 L3 H'; elim H'; auto with datatypes core. intros a b L4 L5 L6 H'0 H'1 H'2. apply InclEqCons; auto. apply InclEqTrans with (y := L4); auto. intros a b L4 L5 L6 H'0 H'1 H'2. apply InclEqTrans with (y := L4); auto. Qed.
imports: Coq(Arith) Coq(Lexicographic_Exponentiation)