(** This lemma used to be an axiom in previous versions of Tarski's axiom system. It is a been shown to a theorem by Gupta in his Phd 1965. *)
(** This corresponds to l9_6 in Tarski's book. *)

Lemma cop3_tsp__tsp : forall A B C D E F P Q, ~ Col D E F ->
Coplanar A B C D -> Coplanar A B C E -> Coplanar A B C F ->
TSP A B C P Q -> TSP D E F P Q.