Table of Contents

Coherent configurations and generalized polygons.- Some thoughts oh the no-three-in-line problem.- A moore-penrose inverse for boolean relation matrices.- The stability index of graphs.- Stability.- An application of combinatorial techniques to a topological problem.- Embeddings of projective planes.- An Extension of kasteleyn's method of enumerating the 1-factors of planar graphs.- A class of block designs having the same parameters as the design of points and lines in a projective 3-space.- Counting stable trees.- The Hamiltonian product of graphs.- Derivable chains containing generalized hall planes.- Characterisation of a pregeometry by its flats.- Eulerian washing machines.- Sum-free sets, difference sets and cyclotomy.- Polyhedral decomposition of trivalent graphs.- Graphs and block designs associated with the three-dimensional unitary groups.- Williamson matrices of even order.- Supersquares.