Historically, there has always been a close connection between Probability Theory and Combinatorial Problems. As more sophisticated techniques have become available in Probability Theory, it has become possible to use such methods in answering some of the more complex questions arising in the study of Combinatorial Systems. The recent growth in computer science has increased the interest in certain combinatorial problems. This book, which uses probabilistic methods to study some difficult combinatorial questions, will be of great interest to those who deal with Combinatorial Structures.