In this paper we present the notions of median useful for the aggregation of preferences and, more generally, in problems of consensus. After the introduction on the general notion of median, the first section studies the median relations of a profile of arbitrary or particular (tournaments,...

We consider here a NP-hard problem related to the Routing and Wavelength Assignment (RWA) problem in optical networks, dealing with Scheduled Lightpath Demands (SLDs). An SLD is a connection demand between two nodes of the network, during a certain time. Given a set of SLDs, we want to assign a...

Pensions reforms have been accelerating in Europe since the 1990s and the beginning of the 2000s : a common trend consists of strengthening the link between the individual contribution period and the level of pension. In a first part of the paper, we show that this common trend takes place...

I examine in detail the motives of bilateral aid allocation decisions, as they are revealed by data on bilateral aid commitments. I identify both self-interest and recipient needs and merits motives in aid allocation. Self-interest motives are related to economic and political ties between...

Most studies on the green tax reform issue point out that environmental taxes exacerbate pre-existing tax distortions, thereby increasing the welfare costs associated with the overall tax code. As a result, the optimal environmental tax should lie below the Pigovian level (or marginal social...