English

A just-infinite iterated monodromy group without the congruence subgroup property

Group Theory 2025-05-27 v1

Abstract

We prove that the iterated monodromy group of the polynomial z2+iz^2+i is just-infinite, regular branch and does not have the congruence subgroup property. This yields the first example of an iterated monodromy group of a polynomial with these properties. Additional information is provided about the congruence kernel, rigid kernel and branch kernel of this group.

Keywords

Cite

@article{arxiv.2505.19649,
  title  = {A just-infinite iterated monodromy group without the congruence subgroup property},
  author = {Santiago Radi},
  journal= {arXiv preprint arXiv:2505.19649},
  year   = {2025}
}

Comments

21 pages, 1 figure