Walter Neumann
Columbia/Barnard

The Casson Invariant Conjecture says that the signature of the Milnor fiber of a complete intersection singularity with homology sphere link should be eight times the Casson invariant of the link. It suggests that the Milnor fiber is a topologically natural coboundary for the link. Recent progress includes a conjectural classification of the 3-manifolds, singularities, and Milnor fibers to which this applies, and a proof of the conjecture for a largish subclass of these.