Perfect Codes in Cayley Graphs of Hajós Groups
Abstract
A perfect code in a graph Γ is an independent set C such that every vertex of Γ outside C has exactly one neighbour in C. A perfect code in a directed graph can be defined similarly by requiring no arc between vertices of C and for every vertex v outside C there exists exactly one vertex u in C such that the arc from u to v exists in Γ. A subset X of an abelian group G is said to be periodic if there exists a non-identity element g of G such that g + X = X. A factorization of G is a pair of nonempty subsets $(A, B)$ of G such that every element g of G can be expressed uniquely as g = a+b with a ∈ A and b ∈ B. If for every factorization $(A, B)$ of an abelian group G at least one of A and B is periodic, then G is said to be a Hajós group. In this paper we classify all Cayley graphs (directed or undirected) of Hajós groups which admit perfect codes, and moreover we determine all perfect codes in such Cayley graphs.
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BibTeX
@article{hafidh2026perfect,
title = {{Perfect Codes in Cayley Graphs of Hajós Groups}},
author = {Yusuf Hafidh and Binzhou Xia and Sanming Zhou},
journal = {The Electronic Journal of Combinatorics},
year = {2026},
month = oct,
doi = {10.37236/14502},
url = {https://www.combinatorics.org/ojs/index.php/eljc/article/view/v33i4p17},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Perfect Codes in Cayley Graphs of Hajós Groups
AU - Yusuf Hafidh
AU - Binzhou Xia
AU - Sanming Zhou
PY - 2026
DA - 2026/10/23
JO - The Electronic Journal of Combinatorics
DO - 10.37236/14502
UR - https://www.combinatorics.org/ojs/index.php/eljc/article/view/v33i4p17
AB - A perfect code in a graph Γ is an independent set C such that every vertex of Γ outside C has exactly one neighbour in C. A perfect code in a directed graph can be defined similarly by requiring no arc between vertices of C and for every vertex v outside C there exists exactly one vertex u in C such that the arc from u to v exists in Γ. A subset X of an abelian group G is said to be periodic if there exists a non-identity element g of G such that g + X = X. A factorization of G is a pair of nonempty subsets $(A, B)$ of G such that every element g of G can be expressed uniquely as g = a+b with a ∈ A and b ∈ B. If for every factorization $(A, B)$ of an abelian group G at least one of A and B is periodic, then G is said to be a Hajós group. In this paper we classify all Cayley graphs (directed or undirected) of Hajós groups which admit perfect codes, and moreover we determine all perfect codes in such Cayley graphs.
SN - 1077-8926
ER -