English

On the existence of reflecting $n$-queens configurations

Combinatorics 2025-08-20 v2 Number Theory

Abstract

In 1967, Klarner proposed a problem concerning the existence of reflecting nn-queens configurations. The problem considers the feasibility of placing nn mutually non-attacking queens on the reflecting chessboard, an n×nn\times n chessboard with a 1×n1\times n "reflecting strip" of squares added along one side of the board. A queen placed on the reflecting chessboard can attack the squares in the same row, column, and diagonal, with the additional feature that its diagonal path can be reflected via the reflecting strip. Klarner noted the equivalence of this problem to a number theory problem proposed by Slater, which asks: for which nn is it possible to pair up the integers 1 through nn with the integers n+1n+1 through 2n2n such that no two of the sums or differences of the nn pairs of integers are the same. We prove the existence of reflecting nn-queens configurations for all sufficiently large nn, thereby resolving both Slater's and Klarner's questions for all but a finite number of integers.

Keywords

Cite

@article{arxiv.2407.12742,
  title  = {On the existence of reflecting $n$-queens configurations},
  author = {Tantan Dai and Tom Kelly},
  journal= {arXiv preprint arXiv:2407.12742},
  year   = {2025}
}

Comments

9 pages, 2 figures, to appear in Forum of Math, Sigma