Abstract. An algorithm to detect invisible relevant persons in a homogeneous social network is studied with computer simulation. The network is effective as a model for contemporary inter-working terrorists where large hub persons do not exist. Absense of large hub persons results in that the observed communication flow is also homogeneous. Clues regarding invisible relevant persons are hardly found in communication records. This task is, therefore, generally difficult. We demonstrate that our algorithm identifies the portion of the market baskets representing communication records, where invisible relevant persons are likely to be hidden, with good precision. 1 Problem The activity of an organization is often under influence of invisible, but relevant persons. The influence is not directly observed. For example, a coordinator, who provides a number of activists with clever plans, communication means, attacking skill, money, etc., is hidden behind a terrorist network. The coordina...