University Libraries Promotion and Tenure Recognition

The predecessor to this book is called Recursively Enumerable Sets and Degrees. It was one of the first books I bought as a student at the University of Heidelberg in Germany. It still holds up well, even though the corners are tattered and some pages have become alarmingly loose. We did not use the book in a course back then, I was just told it was the standard book on the subject, so I wanted to have it. A year later, I came to the United States for the first time, as an exchange student at the University of Illinois. I brought the book with me, and it so happened that I finally got to use it in a course there. That's when I read every line of it (at least twice). Later I taught from this book myself. Soare worked on a new version for a long time, and he often told me about how his views had changed and how he wanted to present the subject in a different way. I agreed with him. That's why I am choosing the new version. It is a great book, and it has made the journey through space and time, from Heidelberg to Penn State with me as a reliable and unassuming companion.