Section Suma_1.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
(** Unicity of the sum. *)
(** Commutativity of the sum. *)
(** CongA preserves SumA. *)
(** Out preserves SumA. *)
(** ABC + 0 =  ABC (two lemmas) *)
(** 0 + DEF = DEF (two lemmas) *)
(** Some permutation properties:*)
(** Basic cases of sum *)

Lemma bet__suma : forall A B C P, A <> B -> B <> C -> P <> B -> Bet A B C ->
SumA A B P P B C A B C.