One-relator Sasakian groups

Abstract

We prove that any one-relator group $G$ is the fundamental group of a compact Sasakian manifold if and only if $G$ is either finite cyclic or isomorphic to the fundamental group of a compact Riemann surface of genus g > 0 with at most one orbifold point of order $n\ge 1$. We also classify all groups of deficiency at least two that are also the fundamental group of some compact Sasakian manifold.