This book contains a collection of articles on the topics mentioned in the title or closely related to them, and is dedicated to Prof Aristide Halanay from the University of Bucharest, Romania, in occasion of his 70th birthday. The authors are in most cases former students of Halanay or research associates from the University of Bucharest, the Mathematical Institute of the Romanian Academy and the Technical University of Bucharest. There are contributions from mathematicians from Finland, Belgium, the United States of America, Morocco, India and Ireland.The topics indicated above are in most...