Boundedness of Dehn surgery slopes admitting hyperbolic $\mathrm{PSL}(2,\mathbb{R})$-representations for two-bridge knots

Fuente: arXiv
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Main Authors: Jiang, Shunjiang, Tao, Ran
Format: Preprint
Published: 2026
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author Jiang, Shunjiang
Tao, Ran
author_facet Jiang, Shunjiang
Tao, Ran
contents We study Dehn fillings on two-bridge knots via non-abelian representations into $\mathrm{PSL}(2,\mathbb{R})$ whose meridian image is hyperbolic. For each fixed nontrivial two-bridge knot, we prove that the set of surgery slopes admitting such representations is bounded. Equivalently, Dehn fillings along slopes with sufficiently large absolute value admit no non-abelian $\mathrm{PSL}(2,\mathbb{R})$ representations with hyperbolic meridian image. The proof combines the Riley polynomial with Khoi's surgery-slope formula. On each admissible real algebraic branch, we express the meridian and longitude translation parameters as functions of the branch parameter and derive uniform endpoint estimates for their quotient. The resulting bound is effective in principle but not optimized. We also provide examples illustrating the parameter sets and endpoint behavior.
format Preprint
id arxiv_https___arxiv_org_abs_2605_30817
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Boundedness of Dehn surgery slopes admitting hyperbolic $\mathrm{PSL}(2,\mathbb{R})$-representations for two-bridge knots
Jiang, Shunjiang
Tao, Ran
Geometric Topology
57K10, 57K31
We study Dehn fillings on two-bridge knots via non-abelian representations into $\mathrm{PSL}(2,\mathbb{R})$ whose meridian image is hyperbolic. For each fixed nontrivial two-bridge knot, we prove that the set of surgery slopes admitting such representations is bounded. Equivalently, Dehn fillings along slopes with sufficiently large absolute value admit no non-abelian $\mathrm{PSL}(2,\mathbb{R})$ representations with hyperbolic meridian image. The proof combines the Riley polynomial with Khoi's surgery-slope formula. On each admissible real algebraic branch, we express the meridian and longitude translation parameters as functions of the branch parameter and derive uniform endpoint estimates for their quotient. The resulting bound is effective in principle but not optimized. We also provide examples illustrating the parameter sets and endpoint behavior.
title Boundedness of Dehn surgery slopes admitting hyperbolic $\mathrm{PSL}(2,\mathbb{R})$-representations for two-bridge knots
topic Geometric Topology
57K10, 57K31
url https://arxiv.org/abs/2605.30817