Two-Dimensional Minimax Latin Hypercube Designs

We investigate minimax Latin hypercube designs in two dimensions for several distance measures.For the l-distance we are able to construct minimax Latin hypercube designs of n points, and to determine the minimal covering radius, for all n.For the l1-distance we have a lower bound for the covering radius, and a construction of minimax Latin hypercube designs for (infinitely) many values of n.We conjecture that the obtained lower bound is attained, except for a few small (known) values of n.For the l2-distance we have generated minimax solutions up to n = 27 by an exhaustive search method.The latter Latin hypercube designs will be included in the website www.spacefillingdesigns.nl.minimax;Latin hypercube designs;circle coverings

Bounds on separated pairs of subgraphs, eigenvalues and related polynomials

We give a bound on the sizes of two sets of vertices at a given minimum distance (a separated pair of subgraphs) in a graph in terms of polynomials and the spectrum of the graph. We find properties of the polynomial optimizing the bound. Explicit bounds on the number of vertices at maximal distance and distance two from a given vertex, and on the size of two equally large sets at maximal distance are given, and we find graphs for which the bounds are tight.Graphs;Eigenvalues;Polynomials;mathematics