English

Zero-sum partitions of Abelian groups of order $2^n$

Combinatorics 2023-06-22 v6 Group Theory

Abstract

The following problem has been known since the 80's. Let Γ\Gamma be an Abelian group of order mm (denoted Γ=m|\Gamma|=m), and let tt and mim_i, 1it1 \leq i \leq t, be positive integers such that i=1tmi=m1\sum_{i=1}^t m_i=m-1. Determine when Γ=Γ{0}\Gamma^*=\Gamma\setminus\{0\}, the set of non-zero elements of Γ\Gamma, can be partitioned into disjoint subsets SiS_i, 1it1 \leq i \leq t, such that Si=mi|S_i|=m_i and sSis=0\sum_{s\in S_i}s=0 for every ii, 1it1 \leq i \leq t. It is easy to check that mi2m_i\geq 2 (for every ii, 1it1 \leq i \leq t) and I(Γ)1|I(\Gamma)|\neq 1 are necessary conditions for the existence of such partitions, where I(Γ)I(\Gamma) is the set of involutions of Γ\Gamma. It was proved that the condition mi2m_i\geq 2 is sufficient if and only if I(Γ){0,3}|I(\Gamma)|\in\{0,3\}. For other groups (i.e., for which I(Γ)3|I(\Gamma)|\neq 3 and I(Γ)>1|I(\Gamma)|>1), only the case of any group Γ\Gamma with Γ(Z2)n\Gamma\cong(Z_2)^n for some positive integer nn has been analyzed completely so far, and it was shown independently by several authors that mi3m_i\geq 3 is sufficient in this case. Moreover, recently Cichacz and Tuza proved that, if Γ|\Gamma| is large enough and I(Γ)>1|I(\Gamma)|>1, then mi4m_i\geq 4 is sufficient. In this paper we generalize this result for every Abelian group of order 2n2^n. Namely, we show that the condition mi3m_i\geq 3 is sufficient for Γ\Gamma such that I(Γ)>1|I(\Gamma)|>1 and Γ=2n|\Gamma|=2^n, for every positive integer nn. We also present some applications of this result to graph magic- and anti-magic-type labelings.

Keywords

Cite

@article{arxiv.2111.05394,
  title  = {Zero-sum partitions of Abelian groups of order $2^n$},
  author = {Sylwia Cichacz and Karol Suchan},
  journal= {arXiv preprint arXiv:2111.05394},
  year   = {2023}
}