fact: Definition npolyX : n.-tuple {poly_n K} := [tuple npolyp n 'X^i | i < n].
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice fintype tuple) mathcomp(bigop binomial finset finfun ssralg countalg finalg poly polydiv) mathcomp(perm fingroup matrix mxalgebra mxpoly vector countalg)