Definition abelem_rV : gT -> rVn := xchoose ab_rV_P.
Local Notation ErV := abelem_rV.

(* Specifications: *)
Lemma abelem_rV_M : {in E &, {morph ErV : x y / (x * y)%g >-> x + y}}.
Canonical abelem_mx_linear g := Linear (abelem_mx_linear_proof g).