Explicit equational bases for the power semirings of S7
Abstract
For every semigroup S, the set π«(S) of all subsets of S and the set π«+(S) of all nonempty subsets of S form additively idempotent semirings under set-theoretic union and elementwise multiplication, called the full and nonempty power semirings of S, respectively. We investigate the finite basis problem for the full and nonempty power semirings π«(S7) and π«+(S7) of the multiplicative reduct of S7, where S7 is the unique nonfinitely based three-element additively idempotent semiring. We provide explicit infinite equational bases for both and prove that they are nonfinitely based. For π«+(S7), we establish a new sufficient condition for an additively idempotent semiring to be nonfinitely based and apply it to obtain the required result. Moreover, we show that the interval [V(π«+(S7)), V(π«(S7))] in the lattice of additively idempotent semiring varieties has the cardinality of the continuum.
Related
BibTeX
@misc{yue2026explicit,
title = {{Explicit equational bases for the power semirings of $S_7$}},
author = {Mengya Yue and Miaomiao Ren and Zidong Gao},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.19957},
eprint = {2609.19957},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.19957},
}
RIS
TY - UNPB
TI - Explicit equational bases for the power semirings of S_7
AU - Mengya Yue
AU - Miaomiao Ren
AU - Zidong Gao
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2609.19957
UR - https://arxiv.org/abs/2609.19957
AB - For every semigroup S, the set π«(S) of all subsets of S and the set π«^+(S) of all nonempty subsets of S form additively idempotent semirings under set-theoretic union and elementwise multiplication, called the full and nonempty power semirings of S, respectively. We investigate the finite basis problem for the full and nonempty power semirings π«(S_7) and π«^+(S_7) of the multiplicative reduct of S_7, where S_7 is the unique nonfinitely based three-element additively idempotent semiring. We provide explicit infinite equational bases for both and prove that they are nonfinitely based. For π«^+(S_7), we establish a new sufficient condition for an additively idempotent semiring to be nonfinitely based and apply it to obtain the required result. Moreover, we show that the interval [V(π«^+(S_7)), V(π«(S_7))] in the lattice of additively idempotent semiring varieties has the cardinality of the continuum.
ER -