Alexander polynomial of sextics

Alexander polynomials of sextics are computed in the case of sextics with only simple singularities or sextics of torus type with arbitrary singularities. We will show that for irreducible sextics, there are only 4 possible Alexander polynomials: (t(2) - t + 1)(j), j = 0, 1, 2, 3. For the computation, we use the method of Libgober and Loeser-Vaquie [5, 7] and the classification result in our previous papers [12, 11].