Warsaw Fall Seminars In Mathematical Economics 1975

On February 20, 1978, the Department of Econometrics of the University of Tilburg organized a symposium on Convex Analysis and Mathematical th Economics to commemorate the 50 anniversary of the University. The general theme of the anniversary celebration was "innovation" and since an important part of the departments' theoretical work is con centrated on mathematical economics, the above mentioned theme was chosen. The scientific part of the Symposium consisted of four lectures, three of them are included in an adapted form in this volume, the fourth lec ture was a mathematical one with the title "On the development of the application of convexity". The three papers included concern recent developments in the relations between convex analysis and mathematical economics. Dr. P.H.M. Ruys and Dr. H.N. Weddepohl (University of Tilburg) study in their paper "Economic theory and duality", the relations between optimality and equilibrium concepts in economic theory and various duality concepts in convex analysis. The models are introduced with an individual facing a decision in an optimization problem. Next, an n person decision problem is analyzed, and the following concepts are defined: optimum, relative optimum, Nash-equilibrium, and Pareto-optimum.

The seminar for which the proceedings are published here evolved from a cooperative research program on bilinear systems and applications to immunology at the Oregon State University and at the University of Rome. The topics include more general forms of variable structure systems which may be divided into categories of mathematical system theory, economic applications and biological applications. Throughout the seminar there was emphasis on the integration of theory and app- cation. In most cases, theoretical derivations are motivated by their need to solve practical problems. In reading the proceedings, it becomes apparent that bilinear systems, quadratic systems and more general variable structure or adaptive systems become natural models in many cases and excellent approximations in others. It is seen that linear systems have very limited use particularly in economics and biology. Variable structure systems are analyzed in terms of structure,volterra kernels, system modelling, parameter identification,- controllability and Lie algebra to mention a few. Certainly, it ia nbt possible to present a complete tre- ment of these numerous topics, but at the Same time the unifying power of the systems approach and variable structure systems is shown.

Since the beginning of the fifties, the ruling paradigm in the discipline of economics has been that of a competitive general equilibrium. Associated dynamic analyses have therefore been preoccupied with the stability of this equilibrium state, corresponding simply to studies of comparative statics. The need to permeate the boundaries of this paradigm in order to open up new pathways for genuine dynamic analysis is now pressing. The contributions contained in this volume spring from this very ambition. A growing circle of economists have recently been inspired by two distinct but complementary sources: (i) the pathbreaking work of Joseph Schumpeter, and (ii) recent contributions to physics, chemistry and theoretical biology. It turns out that problems which are firmly rooted in the economic discipline, such as innovation, technological change, business cycles and economic development, contain many clear parallels with phenomena from the natural sciences such as the slaving principle, adiabatic elimination and self-organization. In such dynamic worlds, adjustment processes and adaptive behaviour are modelled with the aid of the mathematical theory of nonlinear dynamical systems. The dynamics is defined for a much wider set of conditions or states than simply a set of competitive equilibria. A common objective is to study and classify ways in which the qualitative properties of each system change as the parameters describing the system vary.

The purpose of this monograph is to illuminate the central issues of dynamic analysis applied to economic models, using a generally accepted language of the study of dynamical systems at a level of sophistication likely to be understood by an economist versed in elementary topology. Whether an economic system is governed by a first order difference equation or several simultaneous multivalued partial differential equations, its solution is a flow that determines the state of the system given an initial condition and elapsed time. Thus the flow of a system is the central concept from which the theory here expounded develops. The explicit examples and applications herein are discrete time models, but the theoretical re sults hold for continuous time models as well. The supplementary bibliography in cludes several papers at the frontier of set-valued dynamics which may be viewed using the basic concepts defined in this text; all of these works involve demon strating that (almost) all possible trajectories that a system may follow converge to some set of equilibria. The application of set valued dynamical analysis to economic models is pro~ vided to engender in the reader an appreciation for the relevance of these con cepts to economic theory.

The object of this collection of essays is to acquaint the English speaking reader with the work of the IFO Institute for Economic Re search, tlunich, in the field of business cycle surveys. These written surveys of about 10,000 businessmen in the West German economy collect information which is not otherwise contained in the official statis tics. The information in question primarily involves entrepreneurial judgements and anticipations (plans and expectations). These variables have proved to be very useful for economic diagnosis and prognosis. In the meantime, the survey methods developed by the IFO Institute have been adopted by 16 different countries throughout the world. The monthly business cycle surveys carried out by the EEC Commission, Brussels, in the industries of the member countries are also based to a large extent on the IFO methods. This is the first publication in English to furnish a comprehensive review of the IFO survey technique and the possibilities of utilization of this survey method in business cycle research. Efforts to develop new economic indicators on the basis of judgement and anticipation data have not yet terminated; many theoretical and methodical questions have still to be answered, and perhaps many have yet to be posed. Accordingly, the following collection of ten essays is not a final stock-taking but an interim report on several paths taken by the IFO Institute in its search for economic indicators. Possibly, some of these will later prove to have been a roundabout way.