What a wonderful occasion it is to be celebrating 65 years of Hugo Sonn- schein Given his many contributions to economic research and academia more broadly, there is much to celebrate. This volume, presented to Hugo at a confer ence in his honor at the University of Chicago in October 2005, highlights one of his deepest contributions. It is perhaps the hardest to detect from reading his bios and vita; but something that he is famous for among economists in general and economic theorists in particular. It is his incredible record as a mentor and advisor of students. In putting this volume...

When Murat Sertel asked us whether we would be interested in organizing a special issue of the Review of Economic Design on the formation of networks and groups, we were happy to accept because of the growing research on this important topic. We were also pleasantly surprised at the response to our request for submissions to the special issue, receiving a much larger number of sub missions than we had anticipated. In the end we were able to put together two special issues of insightful papers on this topic. Given the growing interest in this topic, we also decided (with encouragement from...

What a wonderful occasion it is to be celebrating 65 years of Hugo Sonn- schein Given his many contributions to economic research and academia more broadly, there is much to celebrate. This volume, presented to Hugo at a confer ence in his honor at the University of Chicago in October 2005, highlights one of his deepest contributions. It is perhaps the hardest to detect from reading his bios and vita; but something that he is famous for among economists in general and economic theorists in particular. It is his incredible record as a mentor and advisor of students. In putting this volume...