English

Multiplicative groups avoiding a fixed group

Number Theory 2024-09-12 v1

Abstract

We know that any finite abelian group GG appears as a subgroup of infinitely many multiplicative groups Zn×\mathbb{Z}_n^\times (the abelian groups of size ϕ(n)\phi(n) that are the multiplicative groups of units in the rings Z/nZ\mathbb{Z}/n\mathbb{Z}). It seems to be less well appeciated that GG appears as a subgroup of almost all multiplicative groups Zn×\mathbb{Z}_n^\times. We exhibit an asymptotic formula for the counting function of those integers whose multiplicative group fails to contain a copy of GG, for all finite abelian groups GG (other than the trivial one-element group).

Keywords

Cite

@article{arxiv.2409.06869,
  title  = {Multiplicative groups avoiding a fixed group},
  author = {Matthias Hannesson and Greg Martin},
  journal= {arXiv preprint arXiv:2409.06869},
  year   = {2024}
}

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20 pages