One Class of Clusterization Problems in Network Models

Abstract

One clustering problem, which arises in design of search systems, is considered. NP-hardness of the general case of the problem is proved. A complexity status is determined for the cases with certain particular structures of the directed graph, such as: Complete Acyclic graph, Path graph, OutTree and InTree graphs. For the cases of Path and InTree graphs the exact algorithms with quadratic complexity are proposed.