English

Homology Covers and Automorphisms: Examples

Geometric Topology 2024-12-04 v5 Complex Variables

Abstract

Let SS be a Riemann surface with a non-abelian fundamental group and for each integer k2k \geq 2 or k=k=\infty, let S~k\widetilde{S}_{k} be its kk-homology cover. The surface S~k\widetilde{S}_{k} admits a group of conformal automorphisms MkH1(S;Zk)M_{k} \cong {\rm H}_{1}(S;{\mathbb Z}_{k}), where Z:=Z{\mathbb Z}_{\infty}:={\mathbb Z}, such that S=S~k/MkS=\widetilde{S}_{k}/M_{k}. If LAut(S)L \leq {\rm Aut}(S), then there is a short exact sequence 1MkL~kL11 \to M_{k} \to \widetilde{L}_{k} \to L \to 1, where L~k\widetilde{L}_{k} is a subgroup of conformal automorphisms of S~k\widetilde{S}_{k}. In general, the above exact sequence does not need to be split. This paper investigates situations when the splitting is or is not obtained.

Keywords

Cite

@article{arxiv.2407.05442,
  title  = {Homology Covers and Automorphisms: Examples},
  author = {Rubén A. Hidalgo},
  journal= {arXiv preprint arXiv:2407.05442},
  year   = {2024}
}

Comments

Changes in the Abstract and the Introduction. Part of the original introduction is now in Section 2. Some edition in Section 3. Some mistakes in Example 5 were corrected

R2 v1 2026-06-28T17:32:02.415Z