Hildegard Dierker

Nonexistence of Constrained Efficient Equilibria When Markets are Incomplete

We consider economies with incomplete markets, production, an a given distribution of initial endowments. The main purpose of the paper is to present a robust example of an economy with only one firm and one good per state in which no production decision entails a constrained efficient outcome. In particular, the unique Dreze equilibrium is dominated by every other production decision.

Price-dispersed preferences and C1 mean demand

In this paper we introduce the concept of price-dispersed preferences. Moreover we state conditions under which economies with price-dispersed preference distributions have a continuously differentiable mean demand function.

Continuous mean demand functions derived from non-convex preferences

Abstract In this paper we show that for a large subset of utility functions in the space of all C1 utility functions and for all prices the mean demand of those consumers whose taste is represented by a given utility function in that subset is uniquely determined. This implies that for a large set of economies mean demand is a continuous function. Our analysis uses derivatives of first and of higher order. The result is essentially a consequence of the multijet transversality theorem.

Product differentiation and market power

Assuming asymmetry across firms and constant unit costs Perloff and Salop (1985) show: If product differentiation increases, the prices rise in a symmetric equilibrium. This raise the question of whether, in general, more product differentiation leads to higher market prices. Giving up the symmetry and the constant unit costs assumptions we present examples in which at least one firm lowers its equilibrium price when product differentiation increases. We formulate a model of product differentiation and state and discuss, within the theory of supermodular games, conditions ensuring that all firms raise their prices in a Nash equilibrium if product differentiation increases.

Objectives of an Imperfectly Competitive Firm: A Surplus Approach

We consider a firm acting strategically on behalf of its shareholder. The price normalization problem arising in general equilibrium models of imperfect competition can be overcome by using the concept of real wealth maximization. This concept is based on shareholders´ aggregate demand and does not involve nay utility comparisons. We explore the efficiency properties of real wealth maxima for the group of shareholders. A strategy is called S-efficient (S stands for shareholders) if there is not other strategy such that shareholders´new total demand can be redistributed in a way that all shareholders will be better off. Our main result states that the set of real wealth maximizing strategies coincides with the set of S-efficient strategies provided that shareholders´social surplus is concave. The concavity assumption is shown to be independent of the commodity bundle used to normalize prices and measure wealth.

Smoothing demand by aggregation with respect to wealth

Abstract We suggest in this paper to treat the problem of smoothing demand by aggregation in a two-step procedure, corresponding to the two different constituents of consumption characteristics, wealth and preferences. Instead of imposing a manifold structure on preferences we exploit the nice structure of wealth-space. The first step of this procedure, aggregation with respect to wealth, is carried out. It is shown that, for any preference, aggregation with respect to wealth yields a mean demand which is almost everywhere C 1 . Moreover, it is shown that for an important class of preferences, vanishing Gaussian curvature of indifference surfaces does not destroy differentiability of the mean demand function.