One of the main problems in current economic theory is to write contracts which are Pareto optimal, incentive compatible, and also implementable as a perfect Bayesian equilibrium of a dynamic, noncooperative game. The question arises whether it is possible to provide Walrasian type or cooperative equilibrium concepts which have these properties. This volume contains original contributions on noncooperative and cooperative equilibrium notions in economies with differential information and provides answers to the above questions. Moreover, issues of stability, learning and continuity of alternative equilibria are also examined.

These original essays focus on a wide range of topics related to Frank Hahn'sdistinguished work in economics. Ranging from market analysis and game theory to the microeconomicfoundations of macroeconomics and from equilibrium and optimality with missing markets to economicsand society, they reflect the diversity of modem research in economic theory. What distinguishesHahn's work and many of the essays in this book is that the motivation often comes from practicalconcerns about unemployment, savings and investment, poverty, or the stability of markets.The essaysin Part I deal with the microeconomic foundations of macroeconomics - a field in which Hahn has madeimportant contributions, most notably in the theory of monetary economics. Topics include anevaluation of Hahn's contribution to the theory of distribution and such macroeconomic themes ascoordination failure, multiple equilibria, and strategic issues.Part II contains recentcontributions to game theory reflecting Hahn's interest in the question of what is rationalbehavior. The essays in Part III concentrate on general-equilibrium theory with missing markets, afield in which Hahn has made major advances. Although the essays address a different set of issues,they share with Hahn's works such themes as market failure, indeterminacy of equilibrium, and therole of money.Partha Dasgupta is Professor of Economics at Cambridge University. Douglas Gale isProfessor of Economics at Boston University. Oliver Hart is Professor of Economics at theMassachusetts Institute of Technology. Eric Maskin is Professor of Economics at HarvardUniversity.

The paper analyzes the effects of informational asymmetries on the market structure of the banking industry in a multi-period model of spatial competition. All lenders face uncertainty with regard to borrowers’ creditworthiness, but, in the process of lending, incumbent banks gather proprietary information about their clients, acquiring an advantage over potential entrants. These informational asymmetries are an important determinant of the industry structure and may represent a barrier to entry for new banks. The paper shows that, in contrast with traditional models of horizontal differentiation, the steady-state equilibrium is characterized by a finite number of banks even in the absence of fixed costs.