(* 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 per2_col_eq : forall A P P' B, A <> P -> A <> P' -> Per A P B -> Per A P' B -> Col P A P' -> P = P'.