Abstract
Interest has centred recently on the application of the theory of directed graphs to social networks. Graph theory provides a vocabulary and a set of measures which enable the formal properties of a social network to be expressed. A social network may be represented by a number of directed graphs each of which depicts some institutional or interactional aspect of the relationships among individuals involved in it. Such directed graphs may be so complex that their properties are not easily ascertained by visual inspection. However, all the properties of a directed graph may be obtained by performing certain operations on its adjacency matrix.)Whilst a computer may be programmed to perform these operations, optical coincidence cards may be adapted to provide a novel and simple alternative method of manipulating boolean matrices up to 50 × 50 in size which is of low cost and does not require special skills or access to special equipment.