English

Liminal ${\rm SL}_2\mathbb{Z}_p$-representations and odd-th cyclic covers of genus one two-bridge knots

Geometric Topology 2026-01-28 v4 Number Theory

Abstract

Let pp be a prime number and let KK be a genus one two-bridge knot. In the spirit of arithmetic topology, we observe that if pp divides the size of the 1st homology group of some odd-th cyclic branched cover of the knot KK, then its group π1(S3K)\pi_1(S^3-K) admits a liminal SL2Zp{\rm SL}_2\mathbb{Z}_p-character, where Zp\mathbb{Z}_p denotes the ring of pp-adic integers. In addition, we discuss the existence of liminal SL2Zp{\rm SL}_2\mathbb{Z}_p-representations and give a remark on a general two-bridge knot. In the course of argument, we also point out a constraint for prime numbers dividing certain Lucas-type sequences by using the Legendre symbols.

Keywords

Cite

@article{arxiv.2501.00323,
  title  = {Liminal ${\rm SL}_2\mathbb{Z}_p$-representations and odd-th cyclic covers of genus one two-bridge knots},
  author = {Honami Sakamoto and Ryoto Tange and Jun Ueki},
  journal= {arXiv preprint arXiv:2501.00323},
  year   = {2026}
}

Comments

11 pages, 1 figure, minor corrections in v2, corrections on the p=2 case in Theorem 1.1 and the tables in Remark 5.2 in v3, Remark 6.5 (1) updated in v4