The Adams operators on connected graded Hopf algebras

Fuente: arXiv
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Auteurs principaux: Li, Y. -Y., Zhou, G. -S.
Format: Preprint
Publié: 2024
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author Li, Y. -Y.
Zhou, G. -S.
author_facet Li, Y. -Y.
Zhou, G. -S.
contents The Adams operators on a Hopf algebra $H$ are the convolution powers of the identity map of $H$. They are also called Hopf powers or Sweedler powers. It is a natural family of operators on $H$ that contains the antipode. We study the linear properties of the Adams operators when $H=\bigoplus_{m\in \mathbb{N}} H_m$ is connected graded. The main result is that for any of such $H$, there exist a PBW type homogeneous basis and a natural total order on it such that the restrictions $Ψ_n|_{H_m}$ of the Adams operators are simultaneously upper triangularizable with respect to this ordered basis. Moreover, the diagonal coefficients are determined in terms of $n$ and a combinatorial number assigned to the basis elements. As an immediate consequence, we obtain a complete description of the characteristic polynomial of $Ψ_n|_{H_m}$, both on eigenvalues and their multiplicities, when $H$ is locally finite and the base field is of characteristic zero. It recovers the main result of the paper [2] by Aguiar and Lauve, where the approach is different from ours.
format Preprint
id arxiv_https___arxiv_org_abs_2402_13774
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Adams operators on connected graded Hopf algebras
Li, Y. -Y.
Zhou, G. -S.
Rings and Algebras
The Adams operators on a Hopf algebra $H$ are the convolution powers of the identity map of $H$. They are also called Hopf powers or Sweedler powers. It is a natural family of operators on $H$ that contains the antipode. We study the linear properties of the Adams operators when $H=\bigoplus_{m\in \mathbb{N}} H_m$ is connected graded. The main result is that for any of such $H$, there exist a PBW type homogeneous basis and a natural total order on it such that the restrictions $Ψ_n|_{H_m}$ of the Adams operators are simultaneously upper triangularizable with respect to this ordered basis. Moreover, the diagonal coefficients are determined in terms of $n$ and a combinatorial number assigned to the basis elements. As an immediate consequence, we obtain a complete description of the characteristic polynomial of $Ψ_n|_{H_m}$, both on eigenvalues and their multiplicities, when $H$ is locally finite and the base field is of characteristic zero. It recovers the main result of the paper [2] by Aguiar and Lauve, where the approach is different from ours.
title The Adams operators on connected graded Hopf algebras
topic Rings and Algebras
url https://arxiv.org/abs/2402.13774