proposition: Lemma parnotmeet: forall A B C D, Par A B C D -> ~ Meet A B C D.
proof: Proof. intros. conclude_def Par. Qed.
imports: GeoCoq.Elements.OriginalProofs.lemma_30helper GeoCoq.Elements.OriginalProofs.lemma_crossimpliesopposite GeoCoq.Elements.OriginalProofs.proposition_30A