or signed minor, n. of a square matrix A is the signed determinant of the submatrix of A obtained by deleting a given row and given column. For example, if row i and column j are deleted from A, then (-1)^{i + j} times the determinant of the resulting (n - 1)-by-(n - 1) matrix is the i,j cofactor of A.
The determinant of A may be computed as the sum of the products of the entries in any one row or column and their respective cofactors. The sum of the products of the entries in one row (or column) with the cofactors of the entries in a different ro w (or column) is zero. See minor.