Force directed embedding of hierarchical cluster graphs

Cluster graphs are a valuable concept to visualize structu-red relational information. Hierarchical cluster graphs im-pose further levels of granularity which may be controlled by the user. In this paper we present a force directed layout adjustment algorithm for hierarchical cluster graphs. Clus-ters and cluster hierarchies respectively, can be dynamically closed or opened which is vital to selectively reduce the in-formation presented by large graphs. In our case such an operation only rearranges the graph locally, therefore pre-serving the mental map of the user. We also present results achieved with our algorithm in the domain of semantic net exploration.