Random generation of subgroups of the modular group with a fixed isomorphism type

Fuente: arXiv
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Main Authors: Bassino, Frédérique, Nicaud, Cyril, Weil, Pascal
Format: Preprint
Published: 2023
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author Bassino, Frédérique
Nicaud, Cyril
Weil, Pascal
author_facet Bassino, Frédérique
Nicaud, Cyril
Weil, Pascal
contents We show how to efficiently count and generate uniformly at random finitely generated subgroups of the modular group $\textsf{PSL}(2,\mathbb{Z})$ of a given isomorphism type. The method to achieve these results relies on a natural map of independent interest, which associates with any finitely generated subgroup of $\textsf{PSL}(2,\mathbb{Z})$ a graph which we call its silhouette, and which can be interpreted as a conjugacy class of free finite index subgroups of $\textsf{PSL}(2,\mathbb{Z})$.
format Preprint
id arxiv_https___arxiv_org_abs_2310_18923
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Random generation of subgroups of the modular group with a fixed isomorphism type
Bassino, Frédérique
Nicaud, Cyril
Weil, Pascal
Group Theory
Combinatorics
20E07, 20F69, 05A15, 05E16, 05C30
We show how to efficiently count and generate uniformly at random finitely generated subgroups of the modular group $\textsf{PSL}(2,\mathbb{Z})$ of a given isomorphism type. The method to achieve these results relies on a natural map of independent interest, which associates with any finitely generated subgroup of $\textsf{PSL}(2,\mathbb{Z})$ a graph which we call its silhouette, and which can be interpreted as a conjugacy class of free finite index subgroups of $\textsf{PSL}(2,\mathbb{Z})$.
title Random generation of subgroups of the modular group with a fixed isomorphism type
topic Group Theory
Combinatorics
20E07, 20F69, 05A15, 05E16, 05C30
url https://arxiv.org/abs/2310.18923