Graph Theory and Network Analysis Group, Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, 69115 Heidelberg, Germany and Department of Computer Science, University of Science and Technology Kaiserslautern, 67663 Kaiserslautern, Germany.|Graph Theory and Network Analysis Group, Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, 69115 Heidelberg, Germany and Department of Computer Science, University of Science and Technology Kaiserslautern, 67663 Kaiserslautern, Germany.|Graph Theory and Network Analysis Group, Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, 69115 Heidelberg, Germany and Department of Computer Science, University of Science and Technology Kaiserslautern, 67663 Kaiserslautern, Germany.