Combinatorics is a fundamental mathematical discipline as well as an essential component of many mathematical areas, and its study has experienced an impressive growth in recent years. While in the past many ofthe basic combinatorial results were obtained mainly by ingenuity and detailed reasoning, without relying on many deep, well developed tools, the modern theory has grown out of this early stage. There are already well developed enumeration methods, some of which are based on deep algebraic techniques. The probabilistic method initiated by Erdos, became one of the most powerful tools in the modern theory, and its study has been fruitful to Combinatorics, as well as to Probability Theory. Algebraic and topological techniques play a crucial role in the modern theory, and Polyhedral Combinatorics, Linear Programming and constructions of designs have been developed extensively. The tight connection between Discrete Mathematics
and Theoretical Computer Science, and the rapid development of the latter in recent years, stimulated the study of algorithmic combinatorics and combinatorial optimization.