The 4thCologne-Bonn-ZermattSymposium: TheDenseInterstellarMedium in Galaxies took place in Zermatt, Switzerland, from September 22nd to 26th, 2003. This symposium continued the series of conferences on the dense interstellar medium which has been organized every 5 years since 1988 by the I. Physikalisches Institut der Unversit] at ] zuKoln. ] Re?ecting the by now well established and fruitful collaboration between the MPI ffur ] ] Radioastronomie, the Radioastronomisches Institut der Universit] at ] Bonn and the I. Physikal- ches Institut der Universit] at ] zu Koln ] in the context of the...

Studying the dynamics of a large number of particles interacting through long-range forces, commonly referred to as the "N-body problem," is a central aspect of many different branches of physics. In recent years, physicists have made significant advances in the development of fast N-body algorithms to deal efficiently with such complex problems. This book gives a thorough introduction to these so-called "tree methods," setting out the basic principles and giving many practical examples of their use. The authors assume no prior specialist knowledge, and they illustrate the techniques...