Minimum entropy coloring

We study an information-theoretic variant of the graph coloring problem in which the objective function to minimize is the entropy of the coloring. The minimum entropy of a coloring is called the chromatic entropy and was shown by Alon and Orlitsky (IEEE Trans. Inform. Theory 42(5):1329–1339, 1996) to play a fundamental role in the problem of coding with side information. In this paper, we consider the minimum entropy coloring problem from a computational point of view. We first prove that this problem is NP-hard on interval graphs. We then show that, for every constant ε>0, it is NP-hard to find a coloring whose entropy is within (1−ε)log n of the chromatic entropy, where n is the number of vertices of the graph. A simple polynomial case is also identified. It is known that graph entropy is a lower bound for the chromatic entropy. We prove that this bound can be arbitrarily bad, even for chordal graphs. Finally, we consider the minimum number of colors required to achieve minimum entropy and prove a Brooks-type theorem. S. Fiorini acknowledges the support from the Fonds National de la Recherche Scientifique and GERAD-HEC Montréal. G. Joret is a F.R.S.-FNRS Research Fellow.     

A comparison of dependence function estimators in multivariate extremes

Various nonparametric and parametric estimators of extremal dependence have been proposed in the literature. Nonparametric methods commonly suffer from the curse of dimensionality and have been mostly implemented in extreme-value studies up to three dimensions, whereas parametric models can tackle higher-dimensional settings. In this paper, we assess, through a vast and systematic simulation study, the performance of classical and recently proposed estimators in multivariate settings. In particular, we first investigate the performance of nonparametric methods and then compare them with classical parametric approaches under symmetric and asymmetric dependence structures within the commonly used logistic family. We also explore two different ways to make nonparametric estimators satisfy the necessary dependence function shape constraints, finding a general improvement in estimator performance either (i) by substituting the estimator with its greatest convex minorant, developing a computational tool to implement this method for dimensions \(D\ge 2\) or (ii) by projecting the estimator onto a subspace of dependence functions satisfying such constraints and taking advantage of Bernstein–Bézier polynomials. Implementing the convex minorant method leads to better estimator performance as the dimensionality increases.     

Bayesian inference for Gaussian excursion set generated Cox processes with set-marking

This work considers spatial Cox point processes where the random intensity is defined by a random closed set such that different point intensities appear in the two phases formed by the random set and its complement. The point pattern is observed as a set of point coordinates in a bounded region W?? ^d together with the information on the phase of the location of each point. This phase information, called set-marking, is not a representative sample from the random set, and hence it cannot be directly used for deducing properties of the random set. Excursion sets of continuous-parameter Gaussian random fields are applied as a flexible model for the random set. Fully Bayesian method and Markov chain Monte Carlo (MCMC) simulation is adopted for inferring the parameters of the model and estimating the random set. The performance of the new approach is studied by means of simulation experiments. Further, two forestry data sets on point patterns of saplings are analysed. The saplings grow in a clear-cut forest area where, before planting and natural seeding, the soil has been mounded forming a blotched soil structure. The tree densities tend to be different in the tilled patches and in the area outside the patches. The coordinates of each sapling have been measured and it is known whether this location is in a patch or outside. This example has been a motivation for the study.     

Documenting Discrimination: A Study of Recruitment Cases Brought to the Norwegian Gender Equality Ombud

This article investigates appointment cases brought to the Gender Equality Ombud over a ten-year period (1985–94). The study presented here aims to explore gender discrimination in recruitment and why it is so hard to document. An advantage of studying appointment cases brought to the Ombud is that the three parties — the plaintiff, the hiring authority and the Ombud — are all engaged in presenting arguments directly concerning gender discrimination. The two key questions are: how do hiring authorities argue to counter assertions of discrimination? And on what grounds are arguments accepted/not accepted by the Ombud? The cases investigated are divided into three categories: cases from male-dominated organizations, woman-dominated organizations and gender-balanced organizations. How the gender of the candidates has influenced the hiring process can only be read indirectly from most cases; hiring authorities usually argue that it is the concern for personal suitability that has been the decisive factor. In the analysis of the cases three main types of justifications of hiring preferences are identified: ‘continuity’, ‘renewal’ and ‘the woman is unfit’. The decision situation of the Ombud is uncertain in most cases. In many cases the juridical expertise of hiring authorities seems to be decisive. The demarcation line is unclear concerning which arguments should be accepted as impartial and which should be rejected because of vagueness or subjectivity.     

Drinking Motives,Alcohol Use,and Sexual Attraction in Youth

Sexual minority youth were found to be more likely to drink alcohol during weekdays compared to heterosexual youth. Drinking during weekdays was associated with consuming alcohol as a coping strategy. Sexual minority youth also more frequently consumed alcohol to eliminate personal worries (coping) and to not be excluded by their peers (conformity). Sexual orientation–related alcohol problems should be addressed at an early stage. Such efforts are likely to be effective if insecurities and stress related to sexual orientation are addressed as well.     

‘Run after time’: the roads of suitcase traders

Since the 1990s, the development of informal trade in trans-frontier places bordering Mongolia has offered opportunities for Mongolian people to develop new trade links with China, Kazakhstan, and Russia. These ‘businessmen of the transition’ or informal ‘suitcase traders’ go abroad along roads opened to and through Russia and China. My article analyses the ‘circulatory roads’ opened by suitcase traders. I take two examples of this activity: Mongolian Kazakh traders who go to Russia and Mongolian traders who go to China. The trans-frontier places reveal the particular ways of being and skills of drivers, retailers and wholesalers.     

Green Care services in the Nordic countries: an integrative literature review

This article reviews Nordic literature on Green Care for people out of work or school, or with mental health- and/or drug-related problems, published from 1995 to April 2014. Green Care is a well-established international concept that uses animals, plants and nature in an active process to offer health-promoting activities for people. Reports, evaluations and scientific articles are included. The main finding was that the Green Care services described in the literature provided positive activities for our target group. Seven main categories emerged during the analysis: mastery and coping, positive effects on mental health, physical activity, structure and meaningfulness, the feeling of dignity produced by performing a decent ordinary job, social gains, animals and nature experienced as being supportive. Essential intervention factors identified can be described as: (i) contact with animals, (ii) supportive natural environments, (iii) the service leader as a significant important other, (iv) social acceptance and fellowship with other participants and (v) meaningful and individually adapted activities in which mastery can be experienced. These five components interact in a holistic way; the synergetic effects extend the sum of the single factors.     

Coparenting in Stepfamilies: A Cluster Analysis

The aim of this study was to identify types of coparenting in stepfamilies based on observational data and to examine whether these types differed regarding marital satisfaction and child adjustment. Forty-five couples attended two videotaped discussion tasks on topics of agreement and disagreement regarding coparenting issues. An exploratory cluster analysis identified three main types of coparenting in stepfamilies: (1) Cooperative coparenting (n = 19), (2) Complementing coparenting (n = 16), and (3) Conflictual coparenting (n = 10). The Complementing coparenting type appeared as a new type of coparenting that had not been described in earlier studies and that might be specific to coparenting between non-biological parents. Comparison between the three clusters showed no differences for marital satisfaction and child adjustment. Each cluster is illustrated by a family case to provide a better understanding of coparenting dynamics in stepfamilies.     

Le faux problème de l'indéfinition de la religion: les origines du ‘problème’ et ses enjeux actuels

When one refuses to participate in shallow debates on the definition of religion, which define in general tactics of declassing the beliefs of others or of under-classing our own beliefs, one recognizes that beyond the emerging patchworked spiritual diversification which emerges in today's advanced industrial societies there is a unified religious dogma. The idea that spirituality will be contradictory to religion does not constitute a pertinent concrete distinction, but occupies a place in this new religious dogma that presents itself as spiritual.