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

Lemma suma2__conga : forall A B C D E F G H I G' H' I',
SumA A B C D E F G H I -> SumA A B C D E F G' H' I' -> CongA G H I G' H' I'.