Let L be a link with n components and let X denote the universal abelian cover of S^{3} - L.
The first homology H_{1}(X) of X may be expressed as a Z[t_{1}^{±}, ...,
t_{n}^{±}] module. This is called the Alexander module of L, denoted A(L).
The multivariable Alexander polynomial Δ(L) of L is the order of A(L), and is unique up to multiplication
by ±1, ±t_{1}, ..., ±t_{n}^{±}.