Three-component link homotopy
In 2019, Schneidermann and Teicher showed that the Kirk invariant classifies two-component link maps of two-spheres in the four-sphere up to link homotopy. In this paper, we construct a three-component link homotopy invariant. We construct two link maps where each component has the same image, and apply our invariant to prove that nevertheless they are not link homotopic. We develop tools to help distinguish between three-component link maps. We then construct a similar invariant for three-component annular link maps. Towards the end of the paper we discuss how to generalise to an $n$-component link map invariant.
math.GT↗