Milnor invariants via unipotent Magnus embeddings

Abstract

We reconfigure the Milnor invariant of links in terms of central group extensions and unipotent Magnus embeddings. We also develop a diagrammatic computation of the invariant and compute the first non-vanishing invariants of the Milnor link and of several other links. Moreover, we refine the original Milnor invariants of higher degree.

arXiv comment15 pages.We revised minors mistakes, and added a comparison with the original Milnor invariant