English

Symmetry groups of non-simply-connected four-manifolds

Geometric Topology 2013-07-26 v2 Algebraic Topology

Abstract

Let MM be a closed, connected, orientable topological four-manifold with H1(M)H_1(M) nontrivial and free abelian, b2(M)0,2b_2(M)\ne 0, 2, and χ(M)0\chi(M)\ne 0. We show that if GG is a finite group of 2-rank 1\le 1 which admits a homologically trivial, locally linear, effective action on MM, then GG must be cyclic. With additional assumptions to ensure orientability of some components of the singular set (e.g. if GG acts by symplectic symmetries, or preserving a spin structure), we also rule out C2×C2C_2 \times C_2 actions. The proofs use equivariant cohomology, localization, and a careful study of the first cohomology groups of the (potential) singular set.

Keywords

Cite

@article{arxiv.0707.3835,
  title  = {Symmetry groups of non-simply-connected four-manifolds},
  author = {Michael McCooey},
  journal= {arXiv preprint arXiv:0707.3835},
  year   = {2013}
}

Comments

16 pages. An earlier version erroneously asserted that surfaces fixed by certain involutions were orientable, and that error invalidated a later proof. This version discusses the problem and corrects the error