(* 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 l13_2_1 : forall A B C D E, TS A B C D -> Per B C A -> Per B D A -> Col C D E
-> Perp A E C D -> CongA C A B D A B
-> CongA B A C D A E /\ CongA B A D C A E /\ Bet C E D.