Reflections on the N + k Queens Problem
Given a regular chessboard, can you place eight queens on it, so that no two queens attack each other? More generally, given a square chessboard with N rows and N columns, can you place N queens on it, so that no two queens attack each other? This puzzle, known as the N queens problem, is old, and famous, and has an extensive history. Here we present a recently formulated elaboration, which we call the N + k queens problem. We describe some of what is known about the N + k queens problem, prove a few new results, and propose some open questions.
College Mathematics Journal, Vol. 40, No. 3, 2009, 204-210.