Require Export GeoCoq.Tarski_dev.Ch14_prod.
Section Order.
Context `{T2D:Tarski_2D}.
Context `{TE:@Tarski_euclidean Tn TnEQD}.

Lemma pos_null_neg : forall O E E' A MA,
Opp O E E' A MA -> Ps O E A \/ O = A \/ Ps O E MA.