Section T6_2.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
(* Lemma t2_8 : forall A B C D E : Tpoint, Bet A B C -> Bet D B E -> Cong A B D B -> Cong B C B E -> Cong A E C D. *)

Lemma colx : forall A B C X Y, A <> B -> Col X Y A -> Col X Y B -> Col A B C -> Col X Y C.