1. Department of Mathematics, University of Kaiserslautern, Erwin-Schrödinger Straße 49, 67653 Kaiserslautern, Germany
2. Department of Business Administration and International Finance, Nürtingen-Geislingen University (HfWU), Sigmaringer Straße 25, 72622 Nürtingen, Germany
3. Department of Financial Mathematics, Fraunhofer ITWM, 67653 Kaiserslautern, Germany