English

Snowflake groups and conjugator length functions with non-integer exponents

Group Theory 2025-12-17 v1

Abstract

We exhibit novel geometric phenomena in the study of conjugacy problems for discrete groups. We prove that the snowflake groups BpqB_{pq}, indexed by pairs of positive integers p>qp>q, have conjugator length functions CL(n)n\text{CL}(n)\simeq n and annular Dehn functions Ann(n)n2α\text{Ann}(n) \simeq n^{2\alpha}, where α=log2(2p/q)\alpha = \log_2(2p/q). Then, building on BpqB_{pq}, we construct groups B~pq+\tilde{B}_{pq}^+, for which CL(n)nα+1\text{CL}(n)\simeq n^{\alpha+1}. Thus the conjugator length spectrum and the spectrum of exponents of annular Dehn functions are both dense in the range [2,)[2,\infty).

Keywords

Cite

@article{arxiv.2512.14038,
  title  = {Snowflake groups and conjugator length functions with non-integer exponents},
  author = {Martin R. Bridson and Timothy R. Riley},
  journal= {arXiv preprint arXiv:2512.14038},
  year   = {2025}
}

Comments

27 pages, 5 figures

R2 v1 2026-07-01T08:26:36.246Z