(** 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_osp__osp : 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 ->
OSP A B C P Q -> OSP D E F P Q.