Z. Lonc Majorization, packing, covering and matroids Z Majcher Some special realizations of partition matrix sequences R. Nedela Covering spaces of locally homogeneous graphs Z Ryjatek N2-locally disconnected graphs G. Schaar On ‘maximal’ Hamiltonian cycles in the square of a block J. Topp Graphs with unique minimum edge dominating sets and graphs with unique max- imum independent sets of vertices H. Vu Dinh On the length of longest dominating cycles in graphs B. Wei Hamiltonian paths and hamiltonian connectivity in graphs M. Woéniak A note on minimal order of a bipartite graph with exactly q quadrilaterals Research problems Author index to volume 121