The finite basis problem for additively idempotent semirings that relate to S_7

Fuente: arXiv
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Main Authors: Gao, Zidong, Jackson, Marcel, Ren, Miaomiao, Zhao, Xianzhong
Format: Preprint
Published: 2025
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author Gao, Zidong
Jackson, Marcel
Ren, Miaomiao
Zhao, Xianzhong
author_facet Gao, Zidong
Jackson, Marcel
Ren, Miaomiao
Zhao, Xianzhong
contents The $3$-element additively idempotent semiring $S_7$ is a nonnitely based algebra of the smallest possible order. In this paper we study the nite basis problem for some additively idempotent semirings that relate to $S_7$. We present a su cient condition under which an additively idempotent semiring variety is nonnitely based and as applications, show that some additively idempotent semiring varieties that contain $S_7$ are also nonnitely based. We then consider the subdirectly irreducible members of the variety $\mathsf{V}(S_7)$ generated by $S_7$. We show that $\mathsf{V}(S_7)$ contains exactly $6$ finitely based subvarieties, all of which sit at the base of the subvariety lattice, then invoke results from the homomorphism theory of Kneser graphs to verify that $\mathsf{V}(S_7)$ contains a continuum of subvarieties.
format Preprint
id arxiv_https___arxiv_org_abs_2501_19049
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The finite basis problem for additively idempotent semirings that relate to S_7
Gao, Zidong
Jackson, Marcel
Ren, Miaomiao
Zhao, Xianzhong
Group Theory
Combinatorics
16Y60, 03C05, 08B15
The $3$-element additively idempotent semiring $S_7$ is a nonnitely based algebra of the smallest possible order. In this paper we study the nite basis problem for some additively idempotent semirings that relate to $S_7$. We present a su cient condition under which an additively idempotent semiring variety is nonnitely based and as applications, show that some additively idempotent semiring varieties that contain $S_7$ are also nonnitely based. We then consider the subdirectly irreducible members of the variety $\mathsf{V}(S_7)$ generated by $S_7$. We show that $\mathsf{V}(S_7)$ contains exactly $6$ finitely based subvarieties, all of which sit at the base of the subvariety lattice, then invoke results from the homomorphism theory of Kneser graphs to verify that $\mathsf{V}(S_7)$ contains a continuum of subvarieties.
title The finite basis problem for additively idempotent semirings that relate to S_7
topic Group Theory
Combinatorics
16Y60, 03C05, 08B15
url https://arxiv.org/abs/2501.19049