This book originated from a course given at the Univcrsidad Aut6noma of Madrid in the Spring of 1994 and in the Universidad Complutense of Madrid in 1995. The goal of these courses is to give the non-specialist an introduction to some old and new ideas in the field of strongly correlated systems, in particular the problems posed by the high-1 superconducting materials. As theoretical physicists, our starting viewpoint to address the problem of strongly correlat ed ferlnion systems and related issues of modern condensed matter physics .is the renormalization group approach applied both to...

This volume, intended as a contribution to the 10th birthday of high Tc-superconductivity, conveys the essential ideas of the field and addresses researchers as well as graduate students. A special feature is the pedagogical treatment of a variety of modern computational methods to deal with non-pertubative effects in strongly correlated systems. Among the topics treated are the Hubbard models, real space renormalization group methods, quantum phase transitions, the non-linear sigma model, spin ladders and layers, and the quantum Hall effect.