proposition: Theorem Disjointf : forall L1 L2 : list A, Disjoint L1 L2 -> Disjoint L1 (map f L2).
proof: Proof. intros L1 L2 H'; elim H'; auto. intros L3 L4; elim L4; simpl in |- *; auto. intros H'0. apply DisjointDef; simpl in |- *; auto. intros a l H'0 H'1. apply DisjointCons1; auto. apply H'0; auto. intros a0 H'2; red in |- *; intros H'3. lapply (H'1 a0); [ intros H'5; case H'5 | idtac ]; auto. red in |- *; intros H'2. lapply (H'1 (f a)); [ intros H'5; case H'5 | idtac ]; auto. Qed.
imports: Coq(Arith) Coq(Lexicographic_Exponentiation)