(* Gabriel Braun April 2013 *)
Require Export GeoCoq.Tarski_dev.Ch13_1.
Section Length_1.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
(** Pappus Desargues *)
(******************** length *********************)

(* Specifications: *)
Lemma lg_exists : forall A B, exists l, Q_Cong l /\ l A B.
Lemma lg_cong : forall l A B C D, Q_Cong l -> l A B -> l C D -> Cong A B C D.
Lemma lg_cong_lg : forall l A B C D, Q_Cong l -> l A B -> Cong A B C D -> l C D.
Lemma lg_sym : forall l A B, Q_Cong l -> l A B -> l B A.
Lemma ex_points_lg : forall l, Q_Cong l -> exists A, exists B, l A B.
End Length_1.