Basic enumeration --
The sieve --
Permutations --
Two classical enumeration problems in graph theory --
Parity and duality --
Connectivity --
Factors of graphs --
Independent sets of points --
Chromatic number --
Extremal problems for graphs --
Spectra of graphs and random walks --
Automorphisms of graphs --
Hypergraphs --
Ramsey theory --
Reconstruction.

The main purpose of this book is to provide help in learning existing techniques in combinatorics. The most effective way of learning such techniques is to solve exercises and problems. This book presents all the material in the form of problems and series of problems (apart from some general comments at the beginning of each chapter)