Graph Powers of Groups
Abstract
The Lights Out Puzzle, played on a graph Γ, has been studied using linear algebra over 𝔽2 and more generally over ℤ/kℤ. We generalize the setting by allowing the states of vertices to be the elements of a group G, where a click in vertex v multiplies the state of v and its neighbors by an element g ∈ G on the right. Starting with the identity element e ∈ G for all vertices, the totality of all achievable state configurations forms a group GΓ. This group generalizes parallel products of group actions and provides a rich structure for analysis. For many graphs, which we term "RA" (reducible to abelian), the problem reduces --- regardless of G --- to a linear algebra question over ℤ. We discuss a chain of five different subgroups consisting of commutators and introduce techniques for showing that families of graphs are RA using each. In particular, using Heisenberg groups, we establish that a graph is RA precisely when a certain lattice spans ℤ|Γ|. While most graphs appear to be RA, we show the odd-dimensional cube graphs Q2n+1 and folded cube graphs □d, for d odd or 2, are not.
Related
BibTeX
@article{cunningham2026graph,
title = {{Graph Powers of Groups}},
author = {Gabe Cunningham and Igor Minevich},
journal = {The Electronic Journal of Combinatorics},
year = {2026},
month = oct,
doi = {10.37236/14315},
url = {https://www.combinatorics.org/ojs/index.php/eljc/article/view/v33i4p16},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Graph Powers of Groups
AU - Gabe Cunningham
AU - Igor Minevich
PY - 2026
DA - 2026/10/23
JO - The Electronic Journal of Combinatorics
DO - 10.37236/14315
UR - https://www.combinatorics.org/ojs/index.php/eljc/article/view/v33i4p16
AB - The Lights Out Puzzle, played on a graph Γ, has been studied using linear algebra over 𝔽_2 and more generally over ℤ/kℤ. We generalize the setting by allowing the states of vertices to be the elements of a group G, where a click in vertex v multiplies the state of v and its neighbors by an element g ∈ G on the right. Starting with the identity element e ∈ G for all vertices, the totality of all achievable state configurations forms a group G^Γ. This group generalizes parallel products of group actions and provides a rich structure for analysis. For many graphs, which we term "RA" (reducible to abelian), the problem reduces --- regardless of G --- to a linear algebra question over ℤ. We discuss a chain of five different subgroups consisting of commutators and introduce techniques for showing that families of graphs are RA using each. In particular, using Heisenberg groups, we establish that a graph is RA precisely when a certain lattice spans ℤ^|Γ|. While most graphs appear to be RA, we show the odd-dimensional cube graphs Q_2n+1 and folded cube graphs □_d, for d odd or 2, are not.
SN - 1077-8926
ER -