Global Instance IncidLP_morphisml : Proper(EqL ==> eq ==> iff) IncidLP.Global Instance IncidLP_morphismr : Proper(eq ==> EqP ==> iff) IncidLP.

Lemma same_side_prime__plane : forall A B C D, same_side' A B C D -> exists p, IncidP A p /\ IncidP B p /\ IncidP C p /\ IncidP D p.