In everyday life we must often reach decisions while knowing that the outcome will not only depend on our own choice, but also on the choices of others. These situations are the focus of epistemic game theory. Unlike classical game theory, it explores how people may reason about their opponents before they make their final choice in a game. Packed with examples and practical problems based on stories from everyday life, this is the first textbook to explain the principles of epistemic game theory. Each chapter is dedicated to one particular, natural way of reasoning. The book then shows how each of these ways of reasoning will affect the final choices that can rationally be made and how these choices can be found by iterative procedures. Moreover, it does so in a way that uses elementary mathematics and does not presuppose any previous knowledge of game theory.

This book is concerned with situations in which several persons reach decisions independently and the final consequence depends, potentially, upon each of the decisions taken. Such situations may be described formally by an extensive form game: a mathematical object which specifies the order in which decisions are to be taken, the information available to the decision makers at each point in time, and the consequence that results for each possible combination of decisions. A necessary requirement for rational behavior in such games is that each decision maker should reach a decision that is optimal, given his preferences over his own decisions. This requirement is far from sufficient, however, since every decision maker should in addition base his preferences upon the conjecture that his opponents will act optimally as well. It is this principle that distinguishes noncooperative game theory from one-person decision theory. The main purpose of Rationality in Extensive Form Games is to discuss different formalizations of this principle in extensive form games, such as backward induction, Nash equilibrium, forward induction and rationalizability, under the assumption that the decision makers' preferences are given by subjective expected utility functions. The various formalizations, or rationality criteria, are illustrated by examples, and the relationships among the different criteria are explored.

I would like to use this preface to thank some persons and institutions which have been important during the various stages of writing this book. First of all, I am grateful to Kluwer Academic Publishers for giving me the opportunity to write this book. I started writing the book in 1998 while I was working at the Departament d'Economia i d'Historia Economica at Universidad Autonoma de Barcelona, and continued the writing job from september 1998 to september 2000 at the Departamento de Economfa at Universidad Carlos III de Madrid. The book has been completed while I was visiting the Department of Quantitative Economics at the University of Maastricht from october 2000 to august 2001. I wish to thank these three departments for their hospitality. The book has improved substantially by comments and critique from the following persons who have read parts of the manuscript: Geir Asheim, Eric van Damme, Janos Flesch, Mari-Angeles de Frutos, Diego Moreno, Hans Peters, Antonio Romero and Dries Vermeulen. I should also mention my discussions with Peter Wakker about the decision-theoretic foundations of noncooperative game theory, which have had an important impact on various parts of the book. Finally, I wish to express my warmest gratitude to my parents, my brother and my sister, and, last but not least, to Cati, to whom I dedicate this book.

In everyday life we must often reach decisions while knowing that the outcome will not only depend on our own choice, but also on the choices of others. These situations are the focus of epistemic game theory. Unlike classical game theory, it explores how people may reason about their opponents before they make their final choice in a game. Packed with examples and practical problems based on stories from everyday life, this is the first textbook to explain the principles of epistemic game theory. Each chapter is dedicated to one particular, natural way of reasoning. The book then shows how each of these ways of reasoning will affect the final choices that can rationally be made and how these choices can be found by iterative procedures. Moreover, it does so in a way that uses elementary mathematics and does not presuppose any previous knowledge of game theory.