Rosenkrantz et al. and Johnson and Papadimitriou constructed families of TSP instances with n cities for which the nearest neighbor rule yields a tour-length that is a factor Ω(log n) above the length of the optimal tour. We describe two new families of TSP instances, for which the nearest neighbor rule shows the same bad behaviour. The instances in the first family are graphical, and the instances in the second family are Euclidean. Our construction and our arguments are extremely simple and suitable for classroom use.
