End T13.
Section T13_2D.
Context `{T2D:Tarski_2D}.
Context `{TE:@Tarski_euclidean Tn TnEQD}.

Lemma not_par_inter_exists : forall A1 B1 A2 B2,
~ Par A1 B1 A2 B2 -> exists X, Col X A1 B1 /\ Col X A2 B2.