Krzysztof R. Apt received his PhD in 1974 in mathematical logic from the University of Warsaw in Poland. He is a senior researcher at CWI, Amsterdam and Professor of Computer Science at the University of Amsterdam. He is the author of three other books: Verification of Sequential and Concurrent Programs (with E.-R. Olderog), From Logic Programming to Prolog, and Principles of Constraint Programming, and has published 50 journal articles and 15 book chapters. He is the founder and the first editor-in-chief of the ACM Transactions on Computational Logic, and past president of the Association for Logic Programming. He is a member of the Academia Europaea (Mathematics and Informatics Section).