Triple linking numbers and surface systems (1709.08478v1)

Abstract: We give a refined value group for the collection of triple linking numbers of links in the 3-sphere. Given two links with the same pairwise linking numbers we show that they have the same refined triple linking number collection if and only if the links admit homeomorphic surface systems. Moreover these two conditions hold if and only if the link exteriors are bordant over $B \mathbb{Z}^n$, and if and only if the third lower central series quotients $\pi/\pi_3$ of the link groups are isomorphic preserving meridians and longitudes. We also show that these conditions imply that the link groups have isomorphic fourth lower central series quotients $\pi/\pi_4$, preserving meridians.