ON THE UNORIENTED SATO-LEVINE INVARIANT

The Sato-Levine invariant for 2-component links with linking number zero is generalized to links with even linking numbers using not necessarily orientable surfaces. It is well defined modulo 4 and completely classifies “unoriented pass equivalence classes” of 2-component proper links. It is shown that it can be expressed in terms of the coefficients of the Conway polynomial and some applications to the Arf invariant are given.