(* Gabriel Braun November 2012 *)
Require Export GeoCoq.Tarski_dev.Ch12_parallel.
Section Quadrilateral.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.

Lemma mid_plg_1 :
forall A B C D M,
A <> C ->
Midpoint M A C -> Midpoint M B D ->
Parallelogram A B C D.