Syzygies of the transfer ideal of the symmetric group

Fuente: arXiv
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Autores principales: Derksen, Harm, Pevzner, Alexandra
Formato: Preprint
Publicado: 2026
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author Derksen, Harm
Pevzner, Alexandra
author_facet Derksen, Harm
Pevzner, Alexandra
contents We consider the modular action of the symmetric group $S_n$ on $R = k[x_1,\ldots,x_n]$ when $\mathrm{char}(k) = p \leq n$. We show that the image of the transfer map $R\to R^{S_n}$ is an elimination ideal $J\cap R^{S_n}$, where $J\subset R^{S_n}[t]$ is generated by $p$ polynomials with generic coefficients. The structure of this elimination ideal depends only on the quotient $q$ when writing $n = qp + r$ with unique remainder $0 \leq r < p$, implying that the image of the transfer also enjoys this stability. We conjecture a determinantal presentation of the elimination ideal and prove it in the case that $q = 2$. Furthermore, we exhibit a GL-equivariant, linear minimal free resolution of a certain initial ideal, allowing us to extract the graded Betti numbers of the elimination ideal.
format Preprint
id arxiv_https___arxiv_org_abs_2604_27341
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Syzygies of the transfer ideal of the symmetric group
Derksen, Harm
Pevzner, Alexandra
Commutative Algebra
13A50, 13D02 (Primary) 05E40 (Secondary)
We consider the modular action of the symmetric group $S_n$ on $R = k[x_1,\ldots,x_n]$ when $\mathrm{char}(k) = p \leq n$. We show that the image of the transfer map $R\to R^{S_n}$ is an elimination ideal $J\cap R^{S_n}$, where $J\subset R^{S_n}[t]$ is generated by $p$ polynomials with generic coefficients. The structure of this elimination ideal depends only on the quotient $q$ when writing $n = qp + r$ with unique remainder $0 \leq r < p$, implying that the image of the transfer also enjoys this stability. We conjecture a determinantal presentation of the elimination ideal and prove it in the case that $q = 2$. Furthermore, we exhibit a GL-equivariant, linear minimal free resolution of a certain initial ideal, allowing us to extract the graded Betti numbers of the elimination ideal.
title Syzygies of the transfer ideal of the symmetric group
topic Commutative Algebra
13A50, 13D02 (Primary) 05E40 (Secondary)
url https://arxiv.org/abs/2604.27341