Two nonfinitely based additively idempotent semirings of order four

Fuente: arXiv
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Main Authors: Yue, Mengya, Ren, Miaomiao, Gao, Zidong
Format: Preprint
Published: 2026
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author Yue, Mengya
Ren, Miaomiao
Gao, Zidong
author_facet Yue, Mengya
Ren, Miaomiao
Gao, Zidong
contents We establish two sufficient conditions for an additively idempotent semiring to be nonfinitely based. As applications, we prove that two specific $4$-element additively idempotent semirings, $S_{(4,545)}$ and $S_{(4,634)}$, whose additive reducts are chains, have no finite basis for their identities. Furthermore, we show that the interval $[\mathsf{V}(S_{(4,545)}),\mathsf{V}(S_{(4,634)})]$ in the lattice of semiring varieties contains \(2^{\aleph_0}\) distinct varieties. Consequently, the join of two finitely based additively idempotent semiring varieties is not necessarily finitely based. Moreover, we obtain the smallest example of a finitely based additively idempotent semiring $S$ whose extension $S^0$ (obtained by adjoining a new element) is nonfinitely based.
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publishDate 2026
record_format arxiv
spellingShingle Two nonfinitely based additively idempotent semirings of order four
Yue, Mengya
Ren, Miaomiao
Gao, Zidong
Rings and Algebras
Group Theory
We establish two sufficient conditions for an additively idempotent semiring to be nonfinitely based. As applications, we prove that two specific $4$-element additively idempotent semirings, $S_{(4,545)}$ and $S_{(4,634)}$, whose additive reducts are chains, have no finite basis for their identities. Furthermore, we show that the interval $[\mathsf{V}(S_{(4,545)}),\mathsf{V}(S_{(4,634)})]$ in the lattice of semiring varieties contains \(2^{\aleph_0}\) distinct varieties. Consequently, the join of two finitely based additively idempotent semiring varieties is not necessarily finitely based. Moreover, we obtain the smallest example of a finitely based additively idempotent semiring $S$ whose extension $S^0$ (obtained by adjoining a new element) is nonfinitely based.
title Two nonfinitely based additively idempotent semirings of order four
topic Rings and Algebras
Group Theory
url https://arxiv.org/abs/2603.00015