I review some properties of D-branes in the SU(2) and SL(2,R) WZW models. I comment on a potential difficulty for the realization of ‘warped brane worlds’ in string theory. This short note is based on a talk given at the Strings’01 conference in Mumbay. Unité mixte du CNRS et de l’Ecole Normale Supérieure, UMR 8549.

Forecast horizons are de ned as long enough planning horizons that ensure agreement of rst period optimal production decisions of nite and in nite horizon problems regardless of changes in future demand. In this paper, we prove forecast horizon existence and provide computational procedures for production planning problems that satisfy the following monotonicity property: for any xed nite plann...

The paper examines within a uni…ed methodology expectational coordination in a series of economic models. The methodology views the predictions associated with the Rational Expectations Hypothesis as reasonable whenever they can be derived from more basic Common Knowledge hypothesis. The paper successively considers a simple non noisy N-dimensional model, standard models with " intrinsic " unce...

This paper explores French assets returns predictability within a VAR setup. Using quarterly data from 1970Q4 to 2006Q4, it turns out that bonds, equities and bills returns are actually predictable. This feature implies that the investment horizon does indeed matter in the asset allocation. The VAR parameters estimates are then used to compute real returns conditional volatility across investme...

We examine the dynamic pricing decision of a …rm facing random demand while selling a …xed stock of two di¤erentiated products over an in…nite horizon. Prices in each period depend on the available stock of both products (varieties). In addition to the standard tradeo¤ between a higher revenue and the probability of selling the product, a higher price for one product also a¤ects the probability...

We study the development of a social norm of trust and reciprocity via the contagious strategy as de ned in Kandori (1992) among a group of strangers. The players anonymously and randomly meet each other and play a binary trust game in the in nite horizon. In order to provide the investors with proper incentives to follow the contagious strategy, the su cient condition requires that there exist...

We prove theorems pertaining to periodic arrays of spherical obstacles which show how the macroscopic limit of the mean free path depends on the scaling of the size of the obstacles. We treat separately the cases where the obstacles are totally and partially absorbing, and we also distinguish between two-dimensional arrays, where our results are optimal, and higher dimensional arrays where they...