intros...
Qed.
Hint Resolve cong_commutativity : sTarski.
(** (Outer) Five segments configuration. *)
Definition OFSC := fun A B C D A' B' C' D' =>
Bet A B C /\ Bet A' B' C' /\
Cong A B A' B' /\ Cong B C B' C' /\
Cong A D A' D' /\ Cong B D B' D'.
Hint Unfold OFSC : Tarski.

(* Specifications: *)
Lemma five_segments_with_def : forall A B C D A' B' C' D',
OFSC A B C D A' B' C' D' -> A<>B -> Cong C D C' D'.