Conjugator Length in Iterated Cyclic Amalgams of Free Groups
Abstract
Let π0 be the set of finitely generated free groups on some countable alphabet and and define πr inductively as the union of πrβ1 with the set of amalgamated free products G1βZZG2, where G1,G2β πrβ1. We show, for all r, that every element of πr has linear conjugator length, quantifying a result of Larsen and extending a result of Kharlampovich and Myasnikov. This is achieved by a linear conjugator length bound on a family of iterated HNN extensions of free groups. Also, in an appendix, we adapt a proof of A. WeiΓ to show that all Generalized Baumslag-Solitar Groups have linear conjugator length. As a consequence, we obtain that one-relator groups with non-trivial center have linear conjugator length, giving evidence for a conjecture of Bridson, Riley, and Sale.
Related
BibTeX
@misc{gillis2026conjugator,
title = {{Conjugator Length in Iterated Cyclic Amalgams of Free Groups}},
author = {Conan Gillis},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.21116},
eprint = {2609.21116},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.21116},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Conjugator Length in Iterated Cyclic Amalgams of Free Groups
AU - Conan Gillis
PY - 2026
DA - 2026/09/21
PB - arXiv
DO - 10.48550/arxiv.2609.21116
UR - https://arxiv.org/abs/2609.21116
AB - Let π_0 be the set of finitely generated free groups on some countable alphabet and and define π_r inductively as the union of π_rβ1 with the set of amalgamated free products G_1β_ZZG_2, where G_1,G_2β π_rβ1. We show, for all r, that every element of π_r has linear conjugator length, quantifying a result of Larsen and extending a result of Kharlampovich and Myasnikov. This is achieved by a linear conjugator length bound on a family of iterated HNN extensions of free groups. Also, in an appendix, we adapt a proof of A. WeiΓ to show that all Generalized Baumslag-Solitar Groups have linear conjugator length. As a consequence, we obtain that one-relator groups with non-trivial center have linear conjugator length, giving evidence for a conjecture of Bridson, Riley, and Sale.
ER -