(* Gabriel Braun April 2013 *)
Require Export GeoCoq.Tarski_dev.Ch12_parallel.
Section L13_1.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
(** Pappus Desargues *)

Lemma perp2_pseudo_trans : forall A B C D E F P, Perp2 A B C D P -> Perp2 C D E F P -> ~ Col C D P ->
Perp2 A B E F P.