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Evaluating the effect of urban intersections on walkability
No full textLecture Notes in Computer Science, Vol. 9789This study proposes an analytical and evaluative method of the performances of urban intersections from the perspective of pedestrians. We further present a case study assessment of walkability of crossings and their conduciveness to walk. Implications in integrated urban and transport planning practice are emphasized as the method is suited to support decision makers involved in urban roads management to identify major spatial and operational problems and to prioritize improvement interventions.nonouirechercheInternationa
The long-term outcomes of early educational differentiation in France
No full textThe French school system has long been divided clearly into two distinct tracks (Baudelot and Establet 1971). Since the end of the nineteenth century, primary-level school was designed to provide a common republican culture to all the pupils of the French nation, thereby leading to a long tradition of centralized education. In contrast, secondary education was designed to teach children from the elites rather than favouring social mobility for all children (Prost 1992). As in many European countries, education in France experienced a long process of democratization during the second half of the twentieth century resulting in a progressive unification of secondary education and in a wider participation on all levels (Duru-Bellat and Kieffer 2000). For example, whereas the share of those passing the upper secondary school diploma [baccalauréat ] in a cohort was 5 per cent in 1950, it reached 20 per cent in 1970 and 74 per cent in 2013. In 1980, 40 per cent of 18 to 24 year olds dropped out after completing lower secondary education (college ) compared to 11.4 per cent in 2012 (DEPP 2014).nonouirechercheInternationa
Parameterized Approximability of Maximizing the Spread of Influence in Networks
No full textIn this paper, we consider the problem of maximizing the spread of influence through a social network. Here, we are given a graph G = (V,E), a positive integer k and a threshold value thr(v) attached to each vertex v ∈ V. The objective is then to find a subset of k vertices to “activate” such that the number of activated vertices at the end of a propagation process is maximum. A vertex v gets activated if at least thr(v) of its neighbors are. We show that this problem is strongly inapproximable in fpt-time with respect to (w.r.t.) parameter k even for very restrictive thresholds. For unanimity thresholds, we prove that the problem is inapproximable in polynomial time and the decision version is W[1]-hard w.r.t. parameter k. On the positive side, it becomes r(n)-approximable in fpt-time w.r.t. parameter k for any strictly increasing function r. Moreover, we give an fpt-time algorithm to solve the decision version for bounded degree graphs.nonnonrechercheInternationa
Translating CSR: A comparative study in the emerging activity of corporate social evaluation in France
No full textouinonouirechercheInternationa
Projector Space Optimization in Quantum Control
No full textWe investigate in this work the numerical resolution of a quantum control problem; the specificity of the approach is that, instead of searching directly for the optimal laser intensity that drives the system toward its target, we consider here as main variable the evolution semigroup i.e. the set of propagators indexed with time. The precise form of the generator of the semigroup (e.g. dipolar) is then enforced as a constraint. We present both an algorithm and associated numerical results.ouinonouirechercheInternationa
Completeness in differential approximation classes
No full textWe study completeness in differential approximability classes. In differential approximation, the quality of an approximation algorithm is the measure of both how far is the solution computed from a worst one and how close is it to an optimal one. We define natural reductions preserving approximation and prove completeness results for the class of the NP optimization problems (class NPO), as well as for DAPX, the differential counterpart of APX, and for a natural subclass of DGLO, the differential counterpart of GLO. We also define class 0-APX of the NPO problems that are not differentially approximable within any ratio strictly greater than 0 unless P = NP. This class is very natural for differential approximation, although has no sense for the standard one. Finally, we prove the existence of hard problems for a subclass of DPTAS, the differential counterpart of PTAS.ouinonouirechercheInternationa
Health expenditures, longevity and growth
No full textThis paper offers an integrated view of the relationships between health spending, medical innovation, health status, growth and welfare. Health spending triggers technological progress, which is a potential source of better outcomes in terms of longevity and quality of life, a direct source of growth for the bio-tech industries and an indirect source of growth through improved of human capital. The latter contributes to GDP per capita through two main channels: higher participation of the population in the labour force and higher labour productivity levels. In turn, income growth induces an increase in health expenditure, as richer countries tend to spend a higher share of their income on health. To analyse these interactions, the paper first focuses on demographic facts, disentangling the role of longevity and carrying out some 'thought experiments' on the indexation of active life on longevity. It then analyses the links between health care expenditures, technology and health status from a micro-level perspective. We investigate empirically the relation between GDP growth and health expenditures and develop a projection method to assess the size of total aggregate expenditures that could be channeled to the health sector up to 2050 for the US, Europe and Japan. We finally assess the potential impact of these health expenditures and better health status on potential growth and productivity.ouinonouirechercheInternationa
Learning preference relations over combinatorial domains
No full textWe address the problem of learning preference relations over multiattribute(or combinatorial) domains. We do so by making hypotheses about thedependence structure between attributes that the preference relation enjoys. Thefirst hypothesis we consider is the simplest one, namely, separability (no dependencesbetween attributes: the preference over the values of each attribute is independentof the values of other attributes); then we consider the more general casewhere the dependence structure takes the form of an acyclic graph. In all cases,what we want to learn is a set of local preference relations (or equivalently, a CPnet)rather than a fully specified preference relation. We consider three forms ofconsistency between a CP-net and a set of examples, and for two of them we givean exact characterization in the case of separability, as well as complexity results.ouinonouirechercheInternationa
Greedy differential approximations for MIN SET COVER
No full textWe present in this paper differential approximation results for min set cover and min weighted set cover. We first show that the differential approximation ratio of the natural greedy algorithm for min set cover is bounded below by 1.365/Delta and above by , where Delta is the maximum set-cardinality in the min set cover-instance. Next, we study an approximation algorithm for min weighted set cover and provide a tight lower bound of 1/Delta.ouinonouirechercheInternationa
Efficient coalitions in Boolean games
No full textBoolean games are a logical setting for representing strategic games in a succinct way, taking advantage of the expressive power and conciseness of propositional logic. A Boolean game consists of a set of players, each of whom controlsa set of propositional variables and has a specific goal expressed by a propositional formula. We show here that Boolean games are a very simple setting, yetsophisticated enough, for studying coalitions. Due to the fact that players havedichotomous preferences, the following notion emerges naturally: a coalition ina Boolean game is efficient if it guarantees that the goal of each member of thecoalition is satisfied. We study the properties of efficient coalitions, and we givea characterization of efficient coalitions.ouinonouirechercheInternationa