On the number of subdirect products involving semigroups of integers and natural numbers

Ashley Clayton, Catherine Reilly, Nik Ruškuc

Research output: Contribution to journalArticlepeer-review

Abstract

In this paper, we extend a recent result that for the (additive) semigroup of positive integers ℕ, there are continuum many subdirect products of ℕ × ℕ up to isomorphism. We prove that for U,V each one of ℤ (the group of integers), ℕ 0 (the monoid of non-negative integers), or ℕ, the direct product U × V contains continuum many (semigroup) subdirect products up to isomorphism.

Original languageEnglish
Article number2650137
JournalJournal of Algebra and Its Applications
Early online date18 Feb 2025
DOIs
Publication statusE-pub ahead of print - 18 Feb 2025

Keywords

  • Semigroup
  • indecomposable element
  • integer
  • natural number
  • subdirect product

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