Kreuzungen in Cluster-Level-Graphen

Clustered graphs are an enhanced graph model with a recursive clustering of the vertices according to a given nesting relation. This prime technique for expressing coherence of certain parts of the graph is used in many applications, such as biochemical pathways and UML class diagrams. For directed clustered graphs usually level drawings are used, leading to clustered level graphs. In this thesis we analyze the interrelation of clusters and levels and their influence on edge crossings and cluster/edge crossings.Cluster-Graphen sind ein erweitertes Graph-Modell mit einem rekursiven Clustering der Knoten entsprechend einer gegebenen Inklusionsrelation. Diese bedeutende Technik um Zusammengehörigkeit bestimmter Teile des Graphen auszudrücken wird in vielen Anwendungen benutzt, etwa biochemischen Reaktionsnetzen oder UML Klassendiagrammen. Für gerichtete Cluster-Graphen werden üblicherweise Level-Zeichnungen verwendet, was zu Cluster-Level-Graphen führt. Diese Arbeit analysiert den Zusammenhang zwischen Clustern und Level und deren Auswirkungen auf Kantenkreuzungen und Cluster/Kanten-Kreuzungen

Clan-Based Incremental Drawing

The stability is an essential issue for incremental drawings. To allow stable updating, means to modify graph slightly (such as adding or deleting an edge or a node) without changing the layout dramatically from previous layout. In this paper, a method for achieving stable incremental directed graph layout by using clan-based graph decomposition is described. For a given directed graph, the clan-based decomposition generates a parse tree. The parse tree, which is used for layout, is also employed in locating changes and maintaining visual stability during incremental drawing. By using the generated parse tree, each incremental update can be done very efficiently