PreprintCC BY 4.0arXiv
Ideal Structures in Idealizations and Cardinalities of Annihilating Ideals
Abstract
We describe the ideals of an idealization Dltimes M by triples (I,N,φ), where I is an ideal of D, N is a submodule of M with IM⊆ N, and φ∈HomD(I,M/N). For a domain D and torsion-free M, the nonzero proper ideals of Dltimes M with nonzero annihilator are exactly 0ltimes N. As an application, for R=ℝ[[t]]ltimesℝ[[t]], the nonzero proper annihilating ideals form a countable set, while the set of all nonzero proper ideals has cardinality 2ℵ0. This answers negatively a question of Behboodi and Rakeei.
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BibTeX
@misc{nikandish2026ideal,
title = {{Ideal Structures in Idealizations and Cardinalities of Annihilating Ideals}},
author = {Reza Nikandish},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.25157},
eprint = {2609.25157},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.25157},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Ideal Structures in Idealizations and Cardinalities of Annihilating Ideals
AU - Reza Nikandish
PY - 2026
DA - 2026/09/21
PB - arXiv
DO - 10.48550/arxiv.2609.25157
UR - https://arxiv.org/abs/2609.25157
AB - We describe the ideals of an idealization Dltimes M by triples (I,N,φ), where I is an ideal of D, N is a submodule of M with IM⊆ N, and φ∈Hom_D(I,M/N). For a domain D and torsion-free M, the nonzero proper ideals of Dltimes M with nonzero annihilator are exactly 0ltimes N. As an application, for R=ℝ[[t]]ltimesℝ[[t]], the nonzero proper annihilating ideals form a countable set, while the set of all nonzero proper ideals has cardinality 2^ℵ_0. This answers negatively a question of Behboodi and Rakeei.
ER -