First of all, we would like to express thanks to our employer, the Institute of Information Theory and Automation (ÚTIA) of the CAS, Prague, for creating an inspiring and friendly environment and for ongoing support of our research. We  thank both universities where we teach, the Czech Technical University, Faculty of Nuclear Science and Physical Engineering and the Charles University, Faculty of Mathematics and Physics, for their support and for administration of all our courses. We would also like to thank the many students in our courses and our tutorial attendees who have asked challenging and stimulating questions.  Many our colleagues and friends helped us with the preparation of the book in various sense. We are most grateful to all of them.

The work on  this book was  partially supported by the Czech Science Foundation under the projects No. GA13-29225S in 2014 and No. GA15-16928S in 2015-16.

Last but not least, we would like to thank our families. Their encouragement and patience was instrumental in completing this book.