proposition: Lemma or9_equiv: forall A1 A2 A3 A4 A5 A6 A7 A8 A9 , or9 A1 A2 A3 A4 A5 A6 A7 A8 A9 <-> A1 \/ A2 \/ A3 \/ A4 \/ A5 \/ A6 \/ A7 \/ A8 \/ A9 .
proof: Proof. intros. split. intros H. rewrite <- or8_equiv. destruct H. constructor 1. exact H. constructor 2. exact H. constructor 3. exact H. constructor 4. exact H. constructor 5. exact H. constructor 6. exact H. constructor 7. exact H. constructor 8. left. exact H. constructor 8. right. exact H. intros H. destruct H. constructor 1. exact H. rewrite <- or8_equiv in H. destruct H. constructor 2. exact H. constructor 3. exact H. constructor 4. exact H. constructor 5. exact H. constructor 6. exact H. constructor 7. exact H. constructor 8. exact H. constructor 9. exact H. Qed.
imports: Coq(Setoid Morphisms)