The purpose of the Handbook of Discrete and Combinatorial Mathematics is to provide a comprehensive reference volume for computer scientists， engineers， mathematicians，as well as students， physical and social scientists， and reference librarians， who need information about discrete and combinatorial mathematics：This first edition of this book was the first resource that presented such information in a ready-reference form designed for all those who use aspects of this subject in their work or studies. This second edition is a major revision of the first edition. It includes extensive additions and updates， summarized later in this preface. The scope of this handbook includes the many areas generally considered to be parts of discrete mathe-matics， focusing on the information considered essential to its application in computer science， engineering， and other disciplines.