The International Erwin Schrödinger Institute is a meeting place that nurtures the development and exchange of ideas among leading experts in mathematics and mathematical physics. In particular, the ESI encourages intellectual exchange between scientists from Eastern Europe and the rest of the world. The purpose of the series, ESI Lectures in Mathematics and Physics, published by the European Mathematical Society (EMS), is to produce selected texts arising from its research program better known to a wider community and easily available to a worldwide audience. It publishes lecture notes on courses given by internationally renowned experts on highly active research topics. In order to make the series attractive to graduate students as well as researchers, special emphasis is given to concise and lively presentations with a level and focus appropriate to a student’s background and at prices commensurate with a student’s means. EMS titles are distributed in the Americas by the American Mathematical Society.