Definition ColG A B C := BetG A B C \/ BetG B C A \/ BetG C A B.

(* Specifications: *)
Lemma col_decG : forall A B C, ColG A B C \/ ~ ColG A B C.
Lemma inner_paschT : forall A B C P Q, BetG A P C -> BetG B Q C -> exists x, BetG P x B /\ BetG Q x A.