Infinite series of quaternionic 1-vertex cube complexes, the doubling construction, and explicit cubical Ramanujan complexes
Group Theory
2019-10-22 v1 Number Theory
Abstract
We construct vertex transitive lattices on products of trees of arbitrary dimension based on quaternion algebras over global fields with exactly two ramified places. Starting from arithmetic examples, we find non-residually finite groups generalizing earlier results of Wise, Burger and Mozes to higher dimension. We make effective use of the combinatorial language of cubical sets and the doubling construction generalized to arbitrary dimension. Congruence subgroups of these quaternion lattices yield explicit cubical Ramanujan complexes, a higher dimensional cubical version of Ramanujan graphs (optimal expanders).
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Cite
@article{arxiv.1808.03290,
title = {Infinite series of quaternionic 1-vertex cube complexes, the doubling construction, and explicit cubical Ramanujan complexes},
author = {Nithi Rungtanapirom and Jakob Stix and Alina Vdovina},
journal= {arXiv preprint arXiv:1808.03290},
year = {2019}
}
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35 pages