English

Group distance magic Cartesian product of two cycles

Combinatorics 2021-09-06 v1

Abstract

Let G=(V,E)G=(V,E) be a graph and Γ\Gamma an Abelian group both of order nn. A Γ\Gamma-distance magic labeling of GG is a bijection  ⁣:VΓ\ell \colon V\rightarrow \Gamma for which there exists μΓ\mu \in \Gamma such that % \sum_{x\in N(v)}\ell (x)=\mu for all vVv\in V, where N(v)N(v) is the neighborhood of vv. Froncek %(\cite{ref_CicAus}) showed that the Cartesian product CmCnC_m \square C_n, m,n3m, n\geq3 is a Zmn\mathbb{Z}_{mn}-distance magic graph if and only if mnmn is even. It is also known that if mnmn is even then CmCnC_m \square C_n has Zα×A\mathbb{Z}_{\alpha}\times \mathcal{A}-magic labeling for any α0(modlcm(m,n))\alpha \equiv 0 \pmod {{\rm lcm}(m,n)} and any Abelian group A\mathcal{A} of order mn/αmn/\alpha. %\cite{ref_CicAus} However, the full characterization of group distance magic Cartesian product of two cycles is still unknown. In the paper we make progress towards the complete solution this problem by proving some necessary conditions. We further prove that for nn even the graph CnCnC_{n}\square C_{n} has a Γ\Gamma-distance magic labeling for any Abelian group Γ\Gamma of order n2n^{2}. Moreover we show that if mnm\neq n, then there does not exist a (Z2)m+n(\mathbb{Z}_2)^{m+n}-distance magic labeling of the Cartesian product C2mC2nC_{2^m} \square C_{2^{n}}. We also give necessary and sufficient condition for CmCnC_{m} \square C_{n} with gcd(m,n)=1\gcd(m,n)=1 to be Γ\Gamma-distance magic.

Keywords

Cite

@article{arxiv.1905.04946,
  title  = {Group distance magic Cartesian product of two cycles},
  author = {Sylwia Cichacz and Dalibor Froncek and Paweł Dyrlaga},
  journal= {arXiv preprint arXiv:1905.04946},
  year   = {2021}
}