  In 2004, some equivalent versions of Polya's permanent problem were listed in
24 versions. However, there is a flaw on the theorem that affirms an
equivalence of version 11 and 12. In order to correct the slip, we provide a
characterization when the determinant and permanent of a given nonnegative
matrix are equal. Moreover, the new characterization yields necessary and
sufficient conditions for the equality of the determinant and permanent of
powers of a given nonnegative matrix.
