proposition: Lemma Incid_line : forall P A B l, A<>B -> IncidentL A l -> IncidentL B l -> Col P A B -> IncidentL P l.
proof: Proof. intros. unfold IncidentL in *. destruct l as [C D HCD]. simpl in *. ColR. Qed.
imports: Morphisms GeoCoq.Axioms.hilbert_axioms GeoCoq.Axioms.parallel_postulates GeoCoq.Meta_theory.Parallel_postulates.tarski_playfair GeoCoq.Meta_theory.Parallel_postulates.SPP_ID GeoCoq.Meta_theory.Dimension_axioms.upper_dim_3 GeoCoq.Meta_theory.Parallel_postulates.parallel_postulates GeoCoq.Utils.triples