Triple Linking of Surfaces in 4-Space
  Triple linking numbers were defined for 3-component oriented surface-links in 4-space using signed triple points on projections in 3-space. In this paper we give an algebraic formulation using intersections of homology classes (or cup products on cohomology groups). We prove that spherical links have trivial triple linking numbers and that triple linking numbers are link homology invariants. 
J. Scott Carter (Univ. of South Alabama), Seiichi Kamada (Osaka City   Univ.), Masahico Saito (Univ. of South Florida), Shin...