Quasi-Kähler groups, 3-manifold groups, and formality (Q543316)

By definition, a manifold \(X\) is quasi-Kähler if \(X = \overline{X}\setminus D,\) where \(\overline{X}\) is a compact, connected Kähler manifold and \(D\) is a divisor with normal crossings. The aim of the paper is to classify 1-formal groups which occur as fundamental groups of both quasi-Kähler manifolds and closed, connected, orientable 3-manifolds. Among other things the authors study formality properties of smooth affine surfaces, links of quasi-homogeneous isolated surface singularities, Brieskorn manifolds, etc. In the quasi-homogeneous case the positive-dimensional components of the first characteristic variety for the associated singularity link are described explicitly. The authors remark that the case of 3-manifolds has been earlier investigated in [\textit{A. Dimca, S. Papadima} and \textit{A. Suciu}, Int. Math. Res. Not. 2008, Article ID rnm119, 36 p. (2008; Zbl 1156.32018)].