Harald Lang

Managerial effort incentives, X-inefficiency and international trade☆

Abstract A contract-theoretic general equilibrium model is employed to investigate the old idea that international competition yields welfare gains by reducing internal slack — ‘X-inefficiency’ — in firms. This popular notion is partly supported in that trade is shown to yield welfare gains by inducing increased supply of a non-contractible factor, which initially is socially under-supplied. However, it is also shown that common statements such as ‘gains from reduced X-inefficiency’ do not seem meaningful. Furthermore, contrary to popular belief, trade need not benefit the X-inefficient economy more than the X-efficient economy.

Comparative statics in dynamic programming models with an application to job search

This paper presents a technique for qualitative comparative statics analysis in dynamic programming models. Let the value function v be the fixed point of a contraction mapping which depends differentially on some exogenous parameter theta. Then the derivative of v with respect to theta exists and is also the fixed point of a contraction mapping. Since this derivative is the fixed point of a contraction mapping its qualitative properties can be investigated using mathematical induction. This comparative statics methodology is illustrated with an application to a model of job search.

General Equilibrium Wage and Price Distributions

This paper extends models of search market equilibrium to incorporate general-equilibrium considerations. The model we treat is one with a single product market and a single labor market. An equilibrium distribution of prices and wages is the result of optimal price- and wage-setting behavior by firms in conjunction with optimal search by individuals. We prove the existence of a degenerate equilibrium and of a two-point dispersion equilibrium.

On sums of subspaces in topological vector spaces and an application in theoretical tomography

We give a sufficient condition in order that a finite sum of closed subspaces of a Frechet space be closed. This is used to solve a problem in theoretical tomography

On measuring the impact of unemployment benefits on the duration of unemployment spell

Abstract Many empirical estimates of the impact of policy changes in unemployment benefit upon the duration of unemployment spell ignore the equilibrium effect, i.e., the demand for labor is assumed to remain unchanged. We argue that this assumption is impermissible.

Price elasticities for residential demand for telephone calling time: An estimate on Swedish data☆

Abstract The paper shows how price elasticities for telephone calling time can be estimated when there is little or no variability in the telephone tariff, taking into account the fact that the price per minute of calling time differs across distance zones as well as according to when the call is made. We apply this method to data on residential demand for telephone calling time in Sweden.

An integral representation formula for systems of convolution equations

AMS(MOS): 46F10 We give an integral representation formula for entire holomorphic solutions of exponential type to systems of convolution equations.