Explorative Graph VisualizationDissertationzurErlangung des akademischen GradesDoktor-Ingenieur (Dr.-Ing.)der Fakultät für Informatik und Elektrotechnikder Universität Rostockvorgelegt vonDipl. Inf. Hans-Jörg Schulz, geb. am 26. Februar 1979 in Rostockaus Bad DoberanRostock, 1. April 2010urn:nbn:de:gbv:28-diss2010-0090-9Principal Advisor: Prof. Dr.-Ing. habil. Heidrun SchumannUniversity of Rostock, GermanyExternal Reviewers: Ao.Univ.-Prof. Dipl.-Ing. Dr.techn. Keith AndrewsTechnical University Graz, AustriaDr. James Abello, Research ProfessorDIMACS Institute, Rutgers University, USADate of Defense: 09-JUN-2010AbstractNetwork structures (graphs) have become a natural part of everyday life and their anal-ysis helps to gain an understanding of their inherent structure and the real-world aspectsthereby expressed. The exploration of graphs is largely supported and driven by visualmeans. The aim of this thesis is to give a comprehensive view on the problems associatedwith these visual means and to detail concrete solution approaches for them. This is doneon all three levels involved: the data level, the representation level, and the task level.In a first step, the intricate dependencies on the level alone are discussedfor the case of implicit tree visualizations. With the awareness of the representation issuesinvolved, a second step takes the characteristics on data level into account, which are mostimportantly graph size and graph type.