End Tensor.
(* Representation sigma type and standard representations. *)
Section StandardRepresentation.
Variables (R : fieldType) (gT : finGroupType) (G : {group gT}).
Local Notation reprG := (mx_representation R G).
Record representation :=
Representation {rdegree; mx_repr_of_repr :> reprG rdegree}.

Lemma mx_repr0 : mx_repr G (fun _ : gT => 1%:M : 'M[R]_0).
Definition dadd_grepr rG1 rG2 :=
Representation (MxRepresentation (add_mx_repr rG1 rG2)).