Differential Topology And General Equilibrium With Complete And Incomplete Markets

General equilibrium In this book we try to cope with the challenging task of reviewing the so called general equilibrium model and of discussing one specific aspect of the approach underlying it, namely, market completeness. With the denomination "general equilibrium" (from now on in short GE) we shall mainly refer to two different things. On one hand, in particular when using the expression "GE approach", we shall refer to a long established methodolog ical tradition in building and developing economic models, which includes, as of today, an enormous amount of contributions, ranging in number by several 1 thousands • On the other hand, in particular when using the expression "stan dard differentiable GE model", we refer to a very specific version of economic model of exchange and production, to be presented in Chapters 8 and 9, and to be modified in Chapters 10 to 15. Such a version is certainly formulated within the GE approach, but it is generated by making several quite restrictive 2 assumptions • Even to list and review very shortly all the collective work which can be ascribed to the GE approach would be a formidable task for several coauthors in a lifetime perspective. The book instead intends to address just a single issue. Before providing an illustration of its main topic, we feel the obligation to say a word on the controversial character of GE. First of all, we should say that we identify the GE approach as being based 3 on three principles .

The purpose of this book is to give a sound economic foundation of finance. Finance is a coherent branch of applied economics that is designed to understand financial markets in order to give advice for practical financial decisions. This book argues that for a sound economic foundation of finance the famous general equilibrium model which in its modern form emphasizes the incompleteness of financial markets is well suited. The aim of the book is to demonstrate that financial markets can be meaningfully embedded into a more general system of markets including, for example, commodity markets. The interaction of these markets can be described via the well known notion of a competitive equilibrium. We argue that for a sound foundation this competitive equilibrium should be unique. In a first step we demonstrate that this essential goal cannot of be achieved based only on the rationality principle, i. e. on the assumption utility maximization of some utility function subject to the budget constraint. In particular we show that this important lack of structure is disturbing as well for the case of mean-variance utility functions which are the basis of the Capital Asset Pricing Model, one of the cornerstones of finance. The final goal of our book is to give reasonable restrictions on the agents' utility functions which lead to a well determined financial markets model.

A leading scholar in the field presents post-1970s developments in the theory of general equilibrium, unified by the concept of equilibrium manifold. In The Equilibrium Manifold, noted economic scholar and major contributor to the theory of general equilibrium Yves Balasko argues that, contrary to what many textbooks want readers to believe, the study of the general equilibrium model did not end with the existence and welfare theorems of the 1950s. These developments, which characterize the modern phase of the theory of general equilibrium, led to what Balasko calls the postmodern phase, marked by the reintroduction of differentiability assumptions and the application of the methods of differential topology to the study of the equilibrium equation. Balasko's rigorous study demonstrates the central role played by the equilibrium manifold in understanding the properties of the Arrow-Debreu model and its extensions. Balasko argues that the tools of differential topology articulated around the concept of equilibrium manifold offer powerful methods for studying economically important issues, from existence and uniqueness to business cycles and economic fluctuations. After an examination of the theory of general equilibrium's evolution in the hundred years between Walras and Arrow-Debreu, Balasko discusses the properties of the equilibrium manifold and the natural projection. He highlights the important role of the set of no-trade equilibria, the structure of which is applied to the global structure of the equilibrium manifold. He also develops a geometric approach to the study of the equilibrium manifold. Applications include stability issues of adjustment dynamics for out-of-equilibrium prices, the introduction of price-dependent preferences, and aspects of time and uncertainty in extensions of the general equilibrium model that account for various forms of market frictions and imperfections. Special effort has been made at reducing the mathematical technicalities without compromising rigor. The Equilibrium Manifold makes clear the ways in which the postmodern” developments of the Arrow-Debreu model improve our understanding of modern market economies.

This book presents a comprehensive treatment of the theory of regular economies, which is one of the most advanced topics in modern general equilibrium theory, emphasizing the basic ideas, the tools and the important applications. Although many notions and tools of differential topology are required to understand the theory, the author chooses a minimum of them and heuristically arranges them; that is, instead of lumping together all the necessary mathematics, the author puts at the beginning of each chapter the minimum mathematics required for the economic analysis of the chapter, so that the reader will not only save much effort on the mathematics but also directly understand how successfully the mathematics is used for the economic issues. Contents: Foundations of Regular Economies: What Is a Regular Economy?; Regular Economies and Genericity; Formalization of Regular Economies; The Number of Equilibria in Regular Economies; Stability of Equilibria in Regular Economies; Transversality and Regular Economies: Space of Utility Functions; Transversality and Regular Economies; Transversality Theorems and Regular Economies; The Number of Extended Equilibria in Regular Economies; Developments of Regular Economies: Production Economy with Linear Activities; Incomplete Markets I; Incomplete Markets II. Readership: Upper level undergraduates, graduate students and researchers involved with the application of mathematics to economic analysis.

General Equilibrium Analysis is a systematic exposition of the Walrasian model of economic equilibrium with a finite number of agents, as formalized by Arrow, Debreu and McKenzie at the beginning of the fifties and since then extensively used, worked and studied. Existence and optimality of general equilibrium are developed repeatedly under different sets of hypothesis which define some general settings and delineate different approaches to the general equilibrium existence problem. The final chapter is devoted to the extension of the general equilibrium model to economies defined on an infinite dimensional commodity space. The objective of General Equilibrium Analysis is to give to each problem in each framework the most general solution, at least for the present state of art. The intended readers are graduate students, specialists and researchers in economics, especially in mathematical economics. The book is appropriate as a class text, or for self-study.

In the area of dynamic economics, David Cass’s work has spawned a number of important lines of research, including the study of dynamic general equilibrium theory, the concept of sunspot equilibria, and general equilibrium theory when markets are incomplete. Based on these contributions, this volume contains new developments in the field, written by Cass's students and co-authors.