Canonical horner_mx_linear := AddLinear horner_mxZ.Section IntegralOverField.mx A d.+1) <= d.
Proof. by exists (n ^ 2)%N; rewrite rank_leq_col. Qed.Definition mxminpoly := 'X^d - mn degree_mxminpoly_proof.
Local Notation d := degree_mxminpoly.