Dietmar is the Vice President IT Solutions at BuyIn, the Procurement Alliance of Deutsche Telekom and Orange, that also provides Procurement services to other telecommunications operators worldwide. Before joining IT Procurement, he has held various positions in IT, e.g. at Deutsche Telekom and Daimler. Dietmar holds a master in mathematics with focus on computer science. He has been a university lecturer in mathematics and a researcher in geometry. Dietmar is the discoverer of the “Bruehl’s lemma”, a mathematical theorem named after him.