Geometric invariants of link cobordism (Q1063909)

In this paper, the author defines new cobordism invariants \(\{\beta^ i(L)\), \(i=1,2,...\}\) for 2-component n-links in \((n+2)\)-sphere, using a geometric operation called the derivative. If \(n>1\), only \(\beta^ 1(L)\) coincides with the Sato-Levine invariant. However, for \(n=1\), they are not new, since it is proved that these are simply the coefficients of Kojima-Yamasaki's \(\eta\)-function after a change of variable [see \textit{S. Kojima} and \textit{M. Yamasaki}, Invent. Math. 54, 213-228 (1979; Zbl 0404.57004)]. These invariants vanish for boundary links and are additive under a band-sum.