fact: Definition rV_prod n (x : 'rV[A * B]_n) : {: 'rV[A]_n * 'rV[B]_n} := (\row_(k < n) (x ``_ k).1, \row_(k < n) (x ``_ k).2).
imports: mathcomp(all_ssreflect ssralg fingroup finalg perm zmodp) mathcomp(matrix mxalgebra vector) ssr_ext f2