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 conga_bet_conga : forall A B C D E F A' C' D' F',
CongA A B C D E F -> A' <> B -> C' <> B -> D' <> E -> F' <> E ->
Bet A B A' -> Bet C B C' -> Bet D E D' -> Bet F E F' ->
CongA A' B C' D' E F'.