FG Praktische Informatik / Softwaresystemtechnik
Abstract. SoftUrbs is a systematic approach to utilize the City metaphor for the visualization and interpretation of large software systems as urban structures. The maincontributions are, firstly, a systematic approach to construct and use these visualizations by adopting thethree-staged cartographic modeling chain and, secondly, the use of force-directed layouts of the city map. The latter provides a framework for flexible and incrementally adaptable layouts, which are necessary to preserve a city's overall morphology throughout the structural evolution of the visualized software system. The distinction between different model stages helps to create uniform and consistent visualizations supporting different usage scenarios. The conceptshave been implemented and were successfully applied in some large scale industry projects.
We introduce energy models for drawing clustered small-world graphs. Clustered means that there exist (probably unknown) sets of nodes with many edges between nodes of the same set and few edges to nodes outside the set. Small-world means that the graph-theoretic distances between nodes are small relative to the number of nodes. Previous force or energy models do not produce satisfactory results for such graphs. In drawings that have minimum energy with respect to our new energy models, different clusters are clearly separated and have interpretable distances.We formally characterize the minimum energy drawings of our new energy mod%ADels and of a class of energy models that contains among others the well-known Fruchterman-Reingold model. These characterizations show 1) in what sense the minimum energy drawings of these energy models fulfill requirements like small, uniform edge lengths, well-distributed nodes, or separated clusters, and 2) what properties of the drawn graph can be inferred from the drawings
In this paper we analyze the efficiency of binary decision diagrams (BDDs) and clock difference diagrams (CDDs) in the verification of timed automata. Therefore we present empirical and analytical complexity results for three communication protocols. The contributions of the analyses are: Firstly, they explain the empirical results. Secondly, they show that BDDs and CDDs of polynomial size exist for the reachability sets of the three protocols. Thirdly, they show that CDD-based tools, which currently use at least exponential space for two of the protocols, will only find polynomial-sized CDDs if they use better variable orders, as the BDD-based tool Rabbit does. Finally, they give insight into the dependency of the BDD and CDD size on properties of the model, in particular the number of automata and the magnitude of the clock values.