Since the appearance in 1975 of this work, the field of combinatorial algorithms has continued its rapid evolution. We have substantially rewritten several of the chapters in order to take account of theoretical or algorithmic improvements, and to clarify the presentation.
The result has been that a number of speedups, storage economies, and program simplifications have been made, some significant new theoretical material such as that in the two new chapters (13 and 14) has been added, and some minor errors have been corrected. As an inducement to any reader who will point out to us an error or misprint, we offer a copy of the complete errata sheet as it stands at that time.
In the spring of 1977 one of us (H.W.) had the pleasure of teaching a course at Swarthmore College based on this book. One of the students in that class, Mr. David Bayer, made a number of original and insight ful observations which have resulted in improvements to our al gorithms. We acknowledge our debt to him and wish him every suc cess in his young career as a mathematician.
