Chessboard squares.

Chetwynd, Amanda G. and Rhodes, S. J. (1995) Chessboard squares. Discrete Mathematics, 141 (1-3). pp. 47-59. ISSN 0012-365X

Abstract

In this paper we consider the problem posed by Häggkvist on finding n × n arrays which are avoidable. An array is said to be avoidable if an n × n latin square on the same symbols can be found which differs from the given array in every cell. We describe a family of arrays, known as chessboard arrays, and classify these arrays as avoidable or non-avoidable.