Some results on general assumptions about the existence of economic equilibrium

In the present paper we maximally use the possibilities provided by the Nash approach and the Kakutani fixed point theorem for proving the existence of an economic equilibrium. We obtain a general existence theorem which does not require a special form for income distribution functions and producer's objectives, independence of consumers' tastes, ordered preference and zero degree homogeneous price dependence. The role of the non-satiation assumption becomes more clear.     

A fixed point algorithm with economic applications

A new fixed point algorithm applicable to large scale economic problems is developed. Motivated by successive approximation the algorithm iterates on a convex combination of the traditional price to price map and the identity map. The actual combination used is determined from the convergence error of the previous iteration. The specified convex combination is guaranteed to be a contraction if the original map is Lipschitz continuous and antitonal. These sufficient conditions are shown to be weaker than the contraction requirement. A simple supply-demand example is presented to show the advantages of this algorithm over successive approximation.     

General equilibrium with externalities: A computational method and urban applications

Many problems of interest to urban economists involve economies with externalities in production or consumption. This paper explains how these problems can be described in such a way that the Scarf Algorithm for the computation of equilibrium prices can be applied. Several examples of applications to economies with prejudice, discrimination, and pollution are given.     

On local relative stability. With special reference to economic applications

Relative stability can be defined as the stability of equilibriumrays. Hence standard method of studying local stability by means of the spectrum of the Jacobian matrix at an equilibriumpoint cannot be used. This problem can often be circumvented by deriving from the original one a new system, having as state variables certainratios between the original variables, so that the equilibrium set will become a point and the standard method will apply. However, the Jacobian matrix at that point will be formed on the basis of a linear combination of the rows of the Jacobian matrix of the original system at a point of its equilibrium set and will normally be much more difficult to analyze. Here a method for studying local relative stability on the basis of the latter matrix is provided.

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Riassunto La stabilità relativa può esser definita come la stabilità diraggi di equilibrio. Quindi il metodo consueto consistente nello studiare la stabilità locale per mezzo dello spettro della matrice giacobiana in unpunto di equilibrio non può esser usato. Tuttavia questo problema spesso può esser superato qualora dal sistema originale possa esser derivato un altro sistema, avente come variabili di sato certi rapporti tra le variabili originarie, cosicché l'insieme di equilibrio del nuovo sistema si riduca ad un punto. In tal caso la matrice giacobiana in tale punto sarà formata sulla base di combinazioni lineari delle righe della matrice giacobiana del sistema originario in un punto del suo insieme di equilibrio, cosicché lo studio qualitativo della prima matrice sarà di regola molto più difficile di quello della seconda. Qui si propone un metodo per studiare la stabilità relativa locale sulla base della seconda matrice.

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I wish to thank M. Bianchi and E. Venini for their comments on previous drafts of this paper.     

Interregional trade and economic integration: A partial equilibrium analysis

The classical comparative static analysis of economic integration is extended to a spatial world by the theory of partial spatial price equilibrium. It is made operational by gravity-like specifications of the demand functions and is applied to a quantitative study of regional effects of the EEC and EFTA formation in Scandinavia and the FRG. Aggregated effects of integration on regional output are presented, based on a hypothetical pre-integration versus post-integration comparison for 1970. It is shown that, contrary to the common views, European economic integration has not been generally detrimental to geographically peripheral areas.     

Convergence to Walrasian equilibrium with minimal information

We consider convergence to Walrasian equilibrium in a situation where firms know only market price and their own cost function. We term this a situation of minimal information. We model the problem as a large population game of Cournot competition. The Nash equilibrium of this model is identical to the Walrasian equilibrium. We apply the best response (BR) dynamic as our main evolutionary model. This dynamic can be applied under minimal information as firms need to know only the market price and the their own cost to compute payoffs. We show that the BR dynamic converges globally to Nash equilibrium in an aggregative game like the Cournot model. Hence, it converges globally to the Walrasian equilibrium under minimal information. We extend the result to some other evolutionary dynamics using the method of potential games.

     

Absolute approximations to equilibrium in markets with non-convex preferences

It is by now a well-known result that non-convexity can be ‘cured’ in large markets. There exist approximations to core allocations and competitive equilibria, in these approximations the excess demand is made small relative to the size of the economy. This work is concerned with absolute approximations, that is, making the excess demand itself arbitrarily small.     

掘金单身经济

一种新的经济形态——单身经济正在兴起。单身经济出现的原因是什么这种以"单身"为诉求点的商业模式及形态又将指向何方     

On financial equilibrium with intermediation costs

This paper studies the set of competitive equilibria in financial economies with intermediation costs. We consider an arbitrary dividend structure, which includes options and equity with limited liabilities. We show a general existence result and upper-hemi continuity of the equilibrium correspondence. Finally, we prove that when intermediation costs approach zero, unbounded volume of asset trades is a necessary and sufficient condition, provided that, there is no financial equilibrium without intermediation costs.     

Minima of vector quadratic forms with applications to statistics

Summary Bush andOlkin (1959) give some results concerning the minimum values of quadratic forms and show some applications of their results to statistics. We generalize some results ofBush andOlkin’s to vector quadratic forms and consider some applications of the results to statistics.     

Differentiability as convergence to perfectly competitive equilibrium

A concept of convergence to perfectly competitive equilibrium, called asymptotically no-surplus, is demonstrated for a sequence of exchange economies in which both the number of agents and the number of commodities is increasing. The no-surplus criterion for perfect competition represents an ordinal extension of the marginal productivity theory of distribution. Its asymptotic definition resembles a Fréchet derivative.     

Macroeconomic scenarios for the south Mediterranean countries: Evidence from general equilibrium model simulation results

The “Arab spring” aftermath calls for a closer look at the developments in the south Mediterranean countries. This paper develops and assesses alternative scenarios for the region up to the year 2030 with the employment of GEM-E3, a computable general equilibrium model. The scenarios quantify three alternative visions of the regional future which assume: (i) south Mediterranean-EU cooperation, (ii) south Mediterranean global opening and (iii) escalation of regional conflicts and failure to cooperate. The scenarios are compared to the baseline scenario, which assumes a continuation of the regional policies observed in the recent past. Assumptions on trade integration, infrastructure, population and governance developments are adopted in each scenario. Infrastructure upgrades and governance improvements within an EU cooperation context are found to benefit the region most. The findings have important policy implications indicating alternatives to be implemented.     

城市湿地可持续利用的经济学分析

随着我国经济的发展,城市化水平的提高,人们深刻认识到:合理、科学利用城市湿地,改善人居环境,优化自然生态,实现社会经济可持续发展,已成为我国城市化进程中的重要环节.从经济学角度分析了城市居民对城市湿地的需求、城市湿地的供给以及城市湿地开发、利用带来的成本和收益.产权、公共财产资源、公共品和外部成本是分析、认识城市湿地可持续利用的关键因素.     

Learnability of an equilibrium with private information

This paper investigates the learnability of an equilibrium with private information. Agents of each type have their own private information about an exogenous variable and conduct adaptive learning with a heterogeneously misspecified perceived laws of motion (PLM) that includes only this variable. The paper shows that the existence of private information has a nonnegative impact on the learnability of the equilibrium; that is, the condition for learnability is unaffected or relaxed by heterogeneity and/or misspecification in PLMs caused by private information. In a New Keynesian model with private information about fundamental shocks, the learnability of the equilibrium is ensured by the Taylor principle of monetary policy. The paper also confirms that these results hold true not only in the presence of private information, but also in a variety of informational structures.     

Fitting nonlinear time-series models with applications to stochastic variance models

New strategies for the implementation of maximum likelihood estimation of nonlinear time series models are suggested. They make use of recent work on the EM algorithm and iterative simulation techniques. The estimation procedures are applied to the problem of fitting stochastic variance models to exchange rate data.     

On-the-job search equilibrium with endogenous unemployment benefits

This paper develops an on-the-job search model with wage posting where unemployment benefits are proportional to past wages. We emphasize that this contributes to increasing the reservation wages of unemployed workers and introduces a feedback effect of the distribution of wages on the distribution of unemployment benefits. We show that the model predictions are consistent with some stylized French facts and quantify the impact of inefficient rejections of low-wage offers by the unemployed. We find that, by reducing the indexing of unemployment benefits to previous earnings and increasing lump-sum transfers, it is possible to increase both employment and welfare.