PreprintCC BY 4.0arXiv
Indecomposable characters of the wreath product of a torus by the infinite block-diagonal symmetric group
Abstract
In this paper we obtain a complete description of all indecomposable characters (central positive-definite functions) of "block-diagonal" inductive limits of semidirect products πNrtimesSN of the compact N-dimensional torus πN with the symmetric group SN. The classification is proved by means of a variant of the ergodic method of Vershik and Kerov, namely by studying the weak limits of characters of finite-dimensional subgroups. As an application of our results, we give another proof of the classification of indecomposable characters of the infinite unitary group with block diagonal embeddings.
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BibTeX
@misc{nessonov2026indecomposable,
title = {{Indecomposable characters of the wreath product of a torus by the infinite block-diagonal symmetric group}},
author = {Nikolay Nessonov and Nhok Tkhai Shon Ngo},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.25275},
eprint = {2609.25275},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.25275},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Indecomposable characters of the wreath product of a torus by the infinite block-diagonal symmetric group
AU - Nikolay Nessonov
AU - Nhok Tkhai Shon Ngo
PY - 2026
DA - 2026/09/21
PB - arXiv
DO - 10.48550/arxiv.2609.25275
UR - https://arxiv.org/abs/2609.25275
AB - In this paper we obtain a complete description of all indecomposable characters (central positive-definite functions) of "block-diagonal" inductive limits of semidirect products π^NrtimesS_N of the compact N-dimensional torus π^N with the symmetric group S_N. The classification is proved by means of a variant of the ergodic method of Vershik and Kerov, namely by studying the weak limits of characters of finite-dimensional subgroups. As an application of our results, we give another proof of the classification of indecomposable characters of the infinite unitary group with block diagonal embeddings.
ER -