Neumann–Wahl Casson invariant conjecture

Let $(X,o)$ be a complete intersection isolated surface singularity, and let its link $\partial(X,o)$ be an integral homology sphere.

Casson invariant conjecture. The Casson invariant of $\partial(X,o)$ is equal to one-eighth of the signature of the Milnor fiber of $(X,o)$.

This conjecture concerns the relationship between the topology of links of complete intersection surface singularities and the topology of their Milnor fibers. It was later proved for splice type singularities with integral homology sphere links by Némethi and Okuma.