English

Characterizing slopes for torus knots, II

Geometric Topology 2021-06-08 v1

Abstract

A slope pq\frac pq is called a characterizing slope for a given knot K0S3K_0\subset S^3 if whenever the pq\frac pq--surgery on a knot KS3K\subset S^3 is homeomorphic to the pq\frac pq--surgery on K0K_0 via an orientation preserving homeomorphism, then K=K0K=K_0. In a previous paper, we showed that, outside a certain finite set of slopes, only the negative integers could possibly be non-characterizing slopes for the torus knot T5,2T_{5,2}. Applying recent work of Baldwin--Hu--Sivek, we improve our result by showing that a nontrivial slope pq\frac pq is a characterizing slope for T5,2T_{5,2} if pq>1\frac pq>-1 and pq{0,1,±12,±13}\frac pq\notin \{0,1, \pm\frac12,\pm\frac13\}. In particular, every nontrivial L-space slope of T5,2T_{5,2} is characterizing for T5,2T_{5,2}. As a consequence, if a nontrivial pq\frac pq-surgery on a non-torus knot in S3S^3 yields a manifold of finite fundamental group, then p>9|p|>9.

Cite

@article{arxiv.2106.02806,
  title  = {Characterizing slopes for torus knots, II},
  author = {Yi Ni and Xingru Zhang},
  journal= {arXiv preprint arXiv:2106.02806},
  year   = {2021}
}

Comments

7 pages, 2 figures

R2 v1 2026-06-24T02:51:44.512Z