English

Liftable mapping class groups of regular abelian covers

Geometric Topology 2024-12-11 v1

Abstract

Let SgS_g be the closed oriented surface of genus g0g \geq 0, and let Mod(Sg)\mathrm{Mod}(S_g) be the mapping class group of SgS_g. For g2g\geq 2, we develop an algorithm to obtain a finite generating set for the liftable mapping class group LModp(Sg)\mathrm{LMod}_p(S_g) of a regular abelian cover pp of SgS_g. A key ingredient of our method is a result that provides a generating set of a group GG acting on a connected graph XX such that the quotient graph X/GX/G is finite. As an application of our algorithm, when kk is prime, we provide a finite generating set for LModpk(S2)\mathrm{LMod}_{p_k}(S_2) for cyclic cover pk:Sk+1S2p_k:S_{k+1}\to S_2. Using the Birman-Hilden theory, when k=2,3k=2,3 and g=2g=2, we also obtain a finite generating set for the normalizer of the Deck transformation group of pkp_k in Mod(Sk+1)\mathrm{Mod}(S_{k+1}). We conclude the paper with an application of our algorithm that gives a finite generating set for LModp(S2)\mathrm{LMod}_p(S_2), where p:S5S2p:S_5\to S_2 is a cover with deck transformation group isomorphic to Z2Z2\mathbb{Z}_2\oplus \mathbb{Z}_2.

Keywords

Cite

@article{arxiv.2412.07319,
  title  = {Liftable mapping class groups of regular abelian covers},
  author = {Neeraj K. Dhanwani and Pankaj Kapari and Kashyap Rajeevsarathy and Ravi Tomar},
  journal= {arXiv preprint arXiv:2412.07319},
  year   = {2024}
}

Comments

27 pages, 9 figures

R2 v1 2026-06-28T20:29:10.646Z