Multivariable Alexander polynomial (${\Delta }_L(t_1,\dots ,t_r)$)

For a link with at least two components, this polynomial is the greatest common divisor of the appropriate maximal minors of an abelianized Alexander matrix, with one variable per oriented component meridian. It is defined up to multiplication by a signed monomial. For a deficiency-one presentation with $g$ generators and $g-1$ relators, use its $(g-1)$-row minors. This normalization gives one for a Hopf link.