Combinatorial Mathematics IV

Comma-free codes and incidence algebras.- Non-orthogonal graeco-latin designs.- An infinite family of skew weighing matrices.- Some elementary aspects of the catalan numbers.- Some new constructions for orthogonal designs.- Bounds of finite relations.- Products of graphs and their spectra.- Some computational results on the spectra of graphs.- A non-imbeddable proper colouring.- Minimal degree of primitive permutation groups.- Number of factors in K-cycle decompositions of permutations.- Some incidence structures of maximal rank.- A theorem on planar graphs.- The number and stability indices of Cn-trees.- On crystallographic colour groups.- Designs from cyclotomy.- Bordered symmetric square roots of the identity matrix.- Integer sequences with given sum and restricted differences.- Orthogonal designs in order sixteen.- Counting arrangements of bishops.- The principle of random union of gametes in a finite population.- The stability index of the product of a path and a tree.- Computation of g(1,3;12).- Embedding proper colourings.- Some large subsquares.