A collection of research papers on combinatorics, with a preface about Paul Erd?s.A collection of surveys and research papers on recent topics of interest in combinatorics. Originally published in journal form, it is here reissued as a book due to its special interest. It is dedicated to Paul Erdös, one of the greatest mathematicians of his century, and includes a new preface, written by friends and colleagues, describing his work and containing many anecdotes about his life. Here is a succinct introduction to important recent ideas in combinatorics for researchers and graduate students.A collection of surveys and research papers on recent topics of interest in combinatorics. Originally published in journal form, it is here reissued as a book due to its special interest. It is dedicated to Paul Erdös, one of the greatest mathematicians of his century, and includes a new preface, written by friends and colleagues, describing his work and containing many anecdotes about his life. Here is a succinct introduction to important recent ideas in combinatorics for researchers and graduate students.This collection of surveys and research papers on recent topics of interest in combinatorics is dedicated to Paul Erdös, who attended the conference and who is represented by two articles in the collection, including one, unfinished, which he was writing on the eve of his sudden death. Erdös was one of the greatest mathematicians of his century and often the subject of anecdotes about his somewhat unusual lifestyle. A new preface, written by friends and colleagues, gives a flavor of his life, including many such stories, and also describes the broad outline and importance of his work in combinatorics and other related fields.Preface; Paul Erd?s: the man and the mathematician (191396) Mikl?s Simonovits and Vera T. S?s; 1. A selection of problems and results in combinatorics Paul Erd?s; 2. Combinatorial Nullstellensatz Noga Alon; 3. Connectedness,lc"