Dr. Kostja Siefen is a Technical Account Manager at Gurobi Optimization. He is a member of the Gurobi Technical Support team and Presales Engineer for the EMEA region. Dr. Siefen holds a Ph.D. in Operations Research from the University of Paderborn (Germany). He joined Gurobi in September 2015 after many years of experience in the development and design of decision support systems using mathematical optimization methods. Before joining Gurobi he worked three years at Daimler Research & Development in Ulm, Germany and at the University of Paderborn as a lecturer and participated in several research projects in the field of optimization methods. Since 1998, before focusing on optimization and during his studies he continuously worked as system administrator, software developer and support engineer for an IT service company. Kostja has been active in academic teaching and customer training since 2009. His responsibilities at Gurobi include training at customer workshops, training events and webinars. Beyond Gurobi, Kostja enjoys spending time with his little daughter and wife, working as a Les Mills group fitness instructor, traveling and good food.