Filip Murlak is Associate Professor at the University of Warsaw, where he lectures on automata, complexity, logic, and databases. His publications include the books Relational and XML Data Exchange (2010) and Foundations of Data Exchange (2014). Damian Niwiński is Professor at the University of Warsaw, where he lectures on automata theory, languages and computations, complexity, algorithmic game theory, and information theory. His publications include the monograph Rudiments of Mu-calculus (with A. Arnold, 2001). Wojciech Rytter is Professor at the University of Warsaw and a member of the Academia Europaea. He is the author of a large number of publications on automata, formal languages, parallel computing and text algorithms. He is a co-author of several books, including Efficient parallel algorithms (1987), Text algorithms (1994) and 125 Exercises in Text Algorithms (2021).

'This book is just enormously fun. One can pick it up and quickly get lost in a fascinating problem. It's a book I would keep on my bookshelf and reach for when I have an exceptionally bright student I wish to challenge.' Anuj Dawar, University of Cambridge

• Part I. Problems: 1. Words, numbers, graphs; 2. Regular languages; 3. Context-free languages; 4. Theory of computation; Part II. Solutions: 1. Words, numbers, graphs; 2. Regular languages; 3. Context-free languages; 4. Theory of computation; Further reading; Index.

Filip Murlak is Associate Professor at the University of Warsaw, where he lectures on automata, complexity, logic, and databases. His publications include the books Relational and XML Data Exchange (2010) and Foundations of Data Exchange (2014). Damian Niwiński is Professor at the University of Warsaw, where he lectures on automata theory, languages and computations, complexity, algorithmic game theory, and information theory. His publications include the monograph Rudiments of Mu-calculus (with A. Arnold, 2001). Wojciech Rytter is Professor at the University of Warsaw and a member of the Academia Europaea. He is the author of a large number of publications on automata, formal languages, parallel computing and text algorithms. He is a co-author of several books, including Efficient parallel algorithms (1987), Text algorithms (1994) and 125 Exercises in Text Algorithms (2021).

'This book is just enormously fun. One can pick it up and quickly get lost in a fascinating problem. It's a book I would keep on my bookshelf and reach for when I have an exceptionally bright student I wish to challenge.' Anuj Dawar, University of Cambridge

• Part I. Problems: 1. Words, numbers, graphs; 2. Regular languages; 3. Context-free languages; 4. Theory of computation; Part II. Solutions: 1. Words, numbers, graphs; 2. Regular languages; 3. Context-free languages; 4. Theory of computation; Further reading; Index.