fact: Definition cofactor n A (i j : 'I_n) : R := (-1) ^+ (i + j) * determinant (row' i (col' j A)).
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype finfun bigop finset fingroup perm order) mathcomp(div prime binomial ssralg countalg finalg zmodp)