Damir Z. Arov is Professor in Mathematics at South-Ukrainian National Pedagogical University in Odessa. He introduced the notion of ╬╡-entropy (predating the KolmogorovтАУSinai entropy), is one of the authors behind the AdamyanтАУArovтАУKrein theory used in HтИЮ control, and developed passive systems theory and the theory of J-contractive matrix-valued functions. He has written approximately 200 journal articles and co-authored three monographs with Professor Harry Dym. Professor Arov, is an honorary doctor from ├Еbo Akademi University, Finland, and has received the Krein prize from the Ukrainian Academy of Sciences.
Olof J. Staffans is Professor Emeritus in Mathematics at ├Еbo Akademi University in Finland. He is the author of Well-Posed Linear Systems (Cambridge, 2005) and a co-author of Volterra Integral and Functional Equations (Cambridge, 1990), and has published more than 100 journal articles. He is a fellow of the American Mathematical Society and a member of the Finnish Society of Sciences and Letters from which he received the E. J. Nystr├╢m award.