Definition block_mxAx := block_mxA. (* Bypass Prenex Implicits *)
(* Bijections mxvec : 'M_(m, n) <----> 'rV_(m * n) : vec_mx *)
Section VecMatrix.
Variables m n : nat.

(* Specifications: *)
Lemma mxvec_cast : #|{:'I_m * 'I_n}| = (m * n)%N.
Coercion pair_of_mxvec_index k (i_k : is_mxvec_index k) :=
let: IsMxvecIndex i j := i_k in (i, j).