The journal 4OR: A Quarterly Journal of Operations Research publishes in almost every issue a state-of-the-art survey authored by a prominent scholar on invitation by the editors. Following an invitation from the late Peter L. Hammer, founder of the Annals of Operations Research, we edited a volume, which appeared in 2007, that collected the eleven surveys published in volumes 1–3 (2003–2005) of 4OR, in order to make them more widely available to the Operations Research community. The new Editor-in-Chief, Endre Boros, found this initiative quite valuable, and decided to promote a follow-up, resulting in a second volume, that collected the eleven surveys published in volumes 4–6 (2006–2008) of the journal. As this series was very successful, it was decided to continue it. The present volume collects the eleven papers that appeared in the next triennium of 4OR (2009–2011). We agreed to give the authors the opportunity to revise and update their texts to include the most recent relevant material. In the first article of the volume the reader will find an introductory description of these surveys. We warmly thank all authors for their contribution.