An interactive three-stage model for mutual funds portfolio selection

The aim of this work is to be a useful instrument for helping finance practitioners on the selection of suitable mutual fund portfolios. The portfolio selection problem is characterized by imprecision and/or vagueness inherent in the required data and more generally, in the context where investors have to make decisions. In order to mitigate these problems, a three stage model has been proposed based on a multi-index model and considering several market scenarios described in an imprecise way by an expert. The proposed fuzzy model allows the Decision Maker to select, by means of an outranking method, a suitable portfolio taking into account the uncertainty related to the market scenarios and the imprecision and/or vagueness associated with the model data.     

Is there still such a thing as the ‘European social model'?

This article presents a definition and characterisation of the ‘European social model’ (ESM), admitting the existence of variants and increasing heterogeneity in institutional and social contexts within the EU in the wake of successive enlargements. The constituent parts of the ESM are compared with data observed in the different countries, in search of empirical evidence of the ESM‘s position as a distinctive model of development, characteristic of Western Europe as opposed to the paths taken by other non‐European developed OECD countries.     

A unified approach to restricted games

There have been two main lines in the literature on restricted games: the first line was started by Myerson (1977) that studied graph-restricted games an the second one was initiated by Faigle (1989). The present paper provides a unified way to look on the literature and establishes connections between the two different lines on restricted games. The strength and advantages of this unified approach becomes clear in the study of the inheritance of the convexity from the game to the restricted game where an interesting result by Nouweland and Borm (1991) on the convexity of graph-restricted games is turned into a direct consequence of the corresponding result by Faigle (1989), by means of this relation. This revised version was published online in June 2006 with corrections to the Cover Date.     

The Lovász Extension of Market Games

The multilinear extension of a cooperative game was introduced by Owen in 1972. In this contribution we study the Lovász extension for cooperative games by using the marginal worth vectors and the dividends. First, we prove a formula for the marginal worth vectors with respect to compatible orderings. Next, we consider the direct market generated by a game. This model of utility function, proposed by Shapley and Shubik in 1969, is the concave biconjugate extension of the game. Then we obtain the following characterization: The utility function of a market game is the Lovász extension of the game if and only if the market game is supermodular. Finally, we present some preliminary problems about the relationship between cooperative games and combinatorial optimization.     

Polysubstance use patterns in underground rave attenders: a cluster analysis

Drug use in mainstream rave parties has been widely documented in a large number of studies. However, not much is known about drug use in underground raves. The purpose of this study is to find out the polysubstance use patterns at underground raves. Two hundred and fifty-two young people between the ages of 18 and 30 who went to underground raves were interviewed. They were given a questionnaire to collect information on drug use at raves. Ravers used a mean of 4.9 different drugs at the last rave they had been to. Over 75% of them used tobacco, alcohol, cannabis, and amphetamine, and over half also used powder ecstasy. Two differentiated use patterns were found: one pattern concentrated more on the use of stimulants and the other on the use of hallucinogens. Underground ravers have a "standard" sociodemographic profile. The use of drugs is much higher than equivalent age group. Higher drug use prevalence than in mainstream rave parties is also observed. Different patterns of use appear which will be necessary to consider in designing preventions and risk reduction strategies,