The topological approach to the aggregation of preferences

(1) A domain of preferences allows for topological aggregation for each number of people if and only if this domain of preferences is contractible. (2) The combination of continuity and the Pareto principle implies the existence of a unique manipulator. (3) Arrow’s theorem can be translated into the previous statement. All of these results are obtained via algebraic topology. This paper introduces some of the tools developed in topology and applies them upon the problem of preference aggregation. This paper is based upon a lecture given at the conference “Mathematical aspects of social choice”, CREM, Université de Caen and CNRS, November 8–10, 2004. I thank the organizers Maurice Salles and Vincent Merlin for their warm hospitality, and the participants for the stimulating discussion. I am indebted to Bart Capéau and Roeland Vervenne for helpful remarks. I thank the referee for combining speed and quality.     

Feeling Attached and Feeling Accepted: Implications for Political Inclusion among Visible Minority Immigrants in Canada

Immigrants’ sense of belonging to their host communities is viewed as a core condition for their successful inclusion, but there is no consensus on which attributes of belonging are most relevant to understanding inclusion, nor is there agreement on how the sense of belonging ought to be measured empirically. This study examines how two related but independent dimensions of belonging help to better understand the political inclusion of visible minority immigrants in Canada. More specifically, it examines the role of feeling attached (immigrants’ feeling toward the host community) and the role of feeling accepted (immigrants’ sense of how their host communities feel about them). We assess the relationship between attachment, acceptance and political inclusion for both first- and second-generation visible minority Canadians; the results suggest there is analytical value in utilising separate measures of attachment and acceptance: political inclusion is more likely when both are stronger.     

Development and Validation of a Scale for the Measurement of Adolescents’ Developmental Assets in the Neighborhood

The aim of this study was to develop a valid and reliable instrument to assess features of a neighborhood that are relevant to the development and adjustment of adolescents. First, a scale was created from a literature review. Second, the content validity of this scale was validated through expert opinion. Finally, the scale was administered to a sample population for analysis of its psychometric properties. The sample consisted of 2,400 adolescents (1,068 boys and 1,332 girls) between ages 12 and 17 who were secondary students in public and private schools in Western Andalusia. The results demonstrate the adequacy of the psychometric properties of the constructed scale.     

Dispersal-related traits of the snail Cornu aspersum along an urbanisation gradient: maintenance of mobility across life stages despite high costs

Urban Ecosystems - The extreme fragmentation of natural habitats due to urbanisation can influence the evolution of dispersal strategies in species persisting in cities. The brown garden snail...     

On simulation and properties of the stable law

The stable distribution, in its many parametrizations, is central to many stochastic processes. Many random variables that occur in the study of Lévy processes are related to it. Good progress has been made recently for simulating various quantities related to the stable law. In this note, we survey exact random variate generators for these distributions. Many distributional identities are also reviewed.     

Topological aggregation, the case of an infinite population

 The literature on infinite Chichilnisky rules considers two forms of anonymity: a weak and a strong. This note introduces a third form: bounded anonymity. It allows us to prove an infinite analogue of the “Chichilnisky– Heal-resolution” close to the original theorem: a compact parafinite CW-complex X admits a bounded anonymous infinite rule if and only if X is contractible. Furthermore, bounded anonymity is shown to be compatible with the finite and the [0, 1]-continuum version of anonymity and allows the construction of convex means in infinite populations. With X=[0, 1], the set of linear bounded anonymous rules coincides with the set of medial limits. Received: 30 October 1993/Accepted: 22 April 1996     

The Balinski–Young Comparison of Divisor Methods is Transitive

The ‘favoring small states’ relation of Balinski and Young (Fair representation, 1982) imposes stronger requirements on the nature of seat transfers than the majorization-ordering introduced by Marshall et al. (Soc Choice Welfare 19(4):885–900, 2002). For divisor methods, however, the two relations coincide. As a consequence, when restricted to the class of divisor methods the Balinski and Young relation is transitive.     

Are “daddy’s boys” just as rich as daddy? The transmission of values between generations

The influence of parents’ savings behaviour on that of their children has often been remarked. This paper attempts to explain this “poids d’Anchise” via a unique French dataset collected by DELTA and TNS-Sofres in 2002 (Pat€r survey), which contains both savings and subjective information for two or three generations of the same family. Parents’ and children’s risk and discounting preferences are significantly positively intergenerationally correlated. The correlation coefficients are around 0.25, so that the two preferences are nonetheless far from identical. In addition, the elasticity of children’s wealth with respect to that of their parents is around 0.22. This correlation is corrected for the influence of age on wealth, and concerns only co-existing generations, that is before the most significant intergenerational transfers have taken place. The analysis of the raw correlations with a series of explanatory variables reveals that over 40 % of this elasticity can be explained by the permanent incomes of the two generations. Each of education and preferences separately account for about 20 %, and previous intergenerational transfers for about 13 %. When permanent income is controlled for, the contribution of savings preferences is around 13 %. The transmission of preferences therefore plays a non-negligible role in the intergenerational transmission of wealth inequalities, but is far from being the most important factor.