Dividing a system into almost unidirectional blocks.- A linear algorithm for five-coloring a planar graph.- On the layering problem of multilayer PWB wiring.- A status on the linear arboricity.- On centrality functions of a graph.- Canonical decompositions of symmetric submodular systems.- The subgraph homeomorphism problem on reducible flow graphs.- Combinatorial problems on series-parallel graphs.- A graph-planarization algorithm and its application to random graphs.- Some common properties for regularizable graphs, edge-critical graphs and b-graphs.- "Dualities" in graph theory and in the related fields viewed from the metatheoretical standpoint.- On central trees of a graph.- On polynomial time computable problems.- Homomorphisms of graphs and their global maps.- Algorithms for some intersection graphs.- An efficient algorithm to find a Hamiltonian circuit in a 4-connected maximal planar graph.- Characterization of polyhex graphs as applied to chemistry.- The two disjoint path problem and wire routing design.