Michael Gelfond has been an extraordinary mentor, teacher, and colleague for many people in the knowledge representation and reasoning (KR&R), logic programming (LP), and answer set programming (ASP) communities.

Michael’s current and former students often like to tell stories about their experience with Michael as a supervisor. These stories invariably begin with meetings in which Michael would review the student’s work. The review would usually not go past the first few paragraphs of the work: Michael would simply find too many mistakes, inaccuracies, parts that need clarification! But these stories also invariably end with the students explaining how Michael’s mentoring turned them into better researchers and better persons, how he taught them to appreciate the importance of accuracy, of slow, deliberate and careful thinking, of academic and personal integrity.

Michael is not only an amazing researcher, who has changed our areas of research in many ways. He is also an amazing person. Even among people who do not share his views, he is deeply respected for his integrity and straightforwardness. He has a keen interest in people, which makes him very caring and understanding – first of all toward his students. Thanks to Michael’s ability of “slow thinking,” which he says he learned from his advisor Nikolai Aleksandrovich Shanin – but which Michael has undoubtedly refined on his own – he can think with astonishing lucidity about any topic, be it scientific or non-scientific.

It is because of all these reasons, and so many more that we could never discuss in this brief preface, that we have decided to honor Michael on the occasion of his 65th birthday with a collection of papers written by his closest friends and colleagues. Several of these papers were presented during the Symposium on Constructive Mathematics in Computer Science, held in Lexington, KY, during October 25–26, 2010.