Section T6_1.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
(** out reflexivity. l6_5 *)
(** out symmetry. *)
(** out transitivity. *)

Lemma l6_16_1 : forall P Q S X, P<>Q -> Col S P Q -> Col X P Q -> Col X P S.