proposition: Theorem appendEqInv : forall L1 L2 L3 : list A, append L1 L2 L3 -> forall m : A, InEq m L3 -> InEq m L1 \/ InEq m L2.
proof: Proof. intros L1 L2 L3 H'; elim H'; simpl in |- *; auto. intros a b L4 L5 L6 H'0 H'1 H'2 m H'3; inversion_clear H'3; auto. case (H'2 m H); intros H'5; auto. intros a b L4 L5 L6 H'0 H'1 H'2 m H'3; inversion_clear H'3; auto. case (H'2 m H); intros H'5; auto. intros a b L4 L5 L6 H'0 H'1 H'2 m H'3; inversion_clear H'3; auto. case (H'2 m H); intros H'5; auto. Qed.
imports: Coq(Arith) Coq(Lexicographic_Exponentiation)