Six (Seven) problems in frame theory

Abstract

Progress in research is due to great scientists. It is due to great mentors and teachers who inspire and challenge their colleagues and students to consider new problems. And it is due to great personalities, whose positive attitude and support make us go the extra mile in order to reach the goal. Professor Butzer has all these properties. It is a great honor for me to be invited to contribute to a book that celebrates him and his work, and I want to thank Professor Schmeisser and Professor Zayed for giving me this opportunity. Finally, at last, but not least: Paul, thanks for all!