The Lamplighter groups have infinite weak cop number
Abstract
The weak-cop number of a graph, a variation of the cop number, is an invariant suitable for infinite graphs and is a quasi-isometric invariant. While for any there exist locally finite infinite graphs with weak-cop number , it is an open question whether there exists locally finite vertex transitive graphs whose weak-cop number is different than and . We test this question on Cayley graphs of wreath products, these are objects known for their exotic geometries. We prove that Cayley graphs of wreath products of nontrivial groups by infinite groups have infinite weak-cop number. The result is proved by defining a new pursuit and evasion game and proving the existence of strategies for the evader. We also include a short argument that Cayley graphs of Thompson's group have infinite weak cop number.
Cite
@article{arxiv.2406.11996,
title = {The Lamplighter groups have infinite weak cop number},
author = {Anders Cornect and Eduardo Martínez-Pedroza},
journal= {arXiv preprint arXiv:2406.11996},
year = {2025}
}
Comments
Version 4. 16 pages. Version accepted for publication by Geometriae Dedicata