Section Suma_1.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
(** Unicity of the sum. *)
(** Commutativity of the sum. *)

Lemma suma_sym : forall A B C D E F G H I, SumA A B C D E F G H I -> SumA D E F A B C G H I.