Section T15.
Context `{T2D:Tarski_2D}.
Context `{TE:@Tarski_euclidean Tn TnEQD}.
(** Lemma 15.2 *)
(** Cong corresponds to length equality.*)
(** Le corresponds to length inequality.*)
(********************************************************)

Lemma ltp__diff_pos : forall O E E' A B D, LtP O E E' A B -> Diff O E E' B A D -> Ps O E D.