SCAI - Institute for Algorithms and Scientific Computing, GMD - German National Research Center for Information Technology, Schloss Birlinghoven, Sankt Augustin, 53754, Germany. Alexander.Zien@gmd.de|SCAI - Institute for Algorithms and Scientific Computing, GMD - German National Research Center for Information Technology, Schloss Birlinghoven, Sankt Augustin, 53754, Germany. Alexander.Zien@gmd.de|SCAI - Institute for Algorithms and Scientific Computing, GMD - German National Research Center for Information Technology, Schloss Birlinghoven, Sankt Augustin, 53754, Germany. Alexander.Zien@gmd.de|SCAI - Institute for Algorithms and Scientific Computing, GMD - German National Research Center for Information Technology, Schloss Birlinghoven, Sankt Augustin, 53754, Germany. Alexander.Zien@gmd.de