The Modular DFT of the Symmetric Group

Fuente: arXiv
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Main Author: Walters, Jackson
Format: Preprint
Published: 2024
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author Walters, Jackson
author_facet Walters, Jackson
contents We describe the discrete Fourier transform (DFT) for a cyclic group when $p|N$ by factoring $x^N-1$ over finite fields and constructing the Fourier transform and its inverse using Bézout's identity for polynomials. For the symmetric group, in the modular case when $p|n!$ we construct the Peirce decomposition using central primitive orthogonal idempotents, yielding a change-of-basis matrix which generalizes the DFT. We compute the unitary DFT for the symmetric group over number fields containing sufficiently many square roots. For $n=3$, we compute the Galois group of the splitting field of the characteristic polynomial. All constructions are implemented in SageMath.
format Preprint
id arxiv_https___arxiv_org_abs_2404_05796
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Modular DFT of the Symmetric Group
Walters, Jackson
Representation Theory
Commutative Algebra
Combinatorics
We describe the discrete Fourier transform (DFT) for a cyclic group when $p|N$ by factoring $x^N-1$ over finite fields and constructing the Fourier transform and its inverse using Bézout's identity for polynomials. For the symmetric group, in the modular case when $p|n!$ we construct the Peirce decomposition using central primitive orthogonal idempotents, yielding a change-of-basis matrix which generalizes the DFT. We compute the unitary DFT for the symmetric group over number fields containing sufficiently many square roots. For $n=3$, we compute the Galois group of the splitting field of the characteristic polynomial. All constructions are implemented in SageMath.
title The Modular DFT of the Symmetric Group
topic Representation Theory
Commutative Algebra
Combinatorics
url https://arxiv.org/abs/2404.05796