English

Domination of the rectangular queen's graph

Combinatorics 2019-12-16 v2

Abstract

The queen's graph Qm×nQ_{m \times n} has the squares of the m×nm \times n chessboard as its vertices; two squares are adjacent if they are in the same row, column, or diagonal of the board. A set DD of squares of Qm×nQ_{m \times n} is a dominating set for Qm×nQ_{m \times n} if every square of Qm×nQ_{m \times n} is either in DD or adjacent to a square in DD. The minimum size of a dominating set of Qm×nQ_{m \times n} is the domination number, denoted by γ(Qm×n)\gamma(Q_{m \times n}). Values of γ(Qm×n),4mn18,\gamma(Q_{m \times n}), \, 4 \leq m \leq n \leq 18, \, are given here, in each case with a file of minimum dominating sets (often all of them, up to symmetry) in an online appendix at https://www.combinatorics.org/ojs/index.php/eljc/article/view/v26i4p45/HTML. In these ranges for mm and nn, monotonicity fails once: γ(Q8×11)=6>5=γ(Q9×11)=γ(Q10×11)=γ(Q11×11)\gamma(Q_{8 \times 11}) = 6 > 5 = \gamma(Q_{9 \times 11}) = \gamma(Q_{10 \times 11}) = \gamma(Q_{11 \times 11}). Lower bounds on γ(Qm×n)\gamma(Q_{m \times n}) are given. In particular, if mnm \leq n then γ(Qm×n)min{m,(m+n2)/4}\gamma(Q_{m \times n}) \geq \min \{ m, \lceil (m+n-2)/4 \rceil \}. A set of squares is independent if no two of its squares are adjacent. The minimum size of an independent dominating set of Qm×nQ_{m \times n} is the independent domination number, denoted by i(Qm×n)i(Q_{m \times n}). Values of i(Qm×n),4mn18,i(Q_{m \times n}), \, 4 \leq m \leq n \leq 18, \, are given here, in each case with some minimum dominating sets. In these ranges for mm and nn, monotonicity fails twice: i(Q8×11)=6>5=i(Q9×11)=i(Q10×11)=i(Q11×11)i(Q_{8 \times 11}) = 6 > 5 = i(Q_{9 \times 11}) = i(Q_{10 \times 11}) = i(Q_{11 \times 11}), and i(Q11×18)=9>8=i(Q12×18)i(Q_{11 \times 18}) = 9 > 8 = i(Q_{12 \times 18}).

Keywords

Cite

@article{arxiv.1606.02060,
  title  = {Domination of the rectangular queen's graph},
  author = {Sándor Bozóki and Péter Gál and István Marosi and William D. Weakley},
  journal= {arXiv preprint arXiv:1606.02060},
  year   = {2019}
}
R2 v1 2026-06-22T14:19:21.512Z