Prenex Implicits char_poly_mx char_poly.

Lemma mx_poly_ring_isom (R : ringType) n' (n := n'.+1) :
exists phi : {rmorphism 'M[{poly R}]_n -> {poly 'M[R]_n}},
[/\ bijective phi,
forall p, phi p%:M = map_poly scalar_mx p,
forall A, phi (map_mx polyC A) = A%:P
& forall A i j k, (phi A)`_k i j = (A i j)`_k].