Approximability results for stable marriage problems with ties

We consider instances of the classical stable marriage problem in which persons may include ties in their preference lists. We show that, in such a setting, strong lower bounds hold for the approximability of each of the problems of finding an egalitarian, minimum regret and sex-equal stable matching. We also consider stable marriage instances in which persons may express unacceptable partners in addition to ties. In this setting, we prove that there are constants delta, delta' such that each of the problems of approximating a maximum and minimum cardinality stable matching within factors of delta, delta' (respectively) is NP-hard, under strong restrictions. We also give an approximation algorithm for both problems that has a performance guarantee expressible in terms of the number of lists with ties. This significantly improves on the best-known previous performance guarantee, for the case that the ties are sparse. Our results have applications to large-scale centralized matching schemes

Technological and environmental risks in the context of climate change.

Considering the importance of the debate on the topic of disasters related to landslides, flooding and technological risks, under international and more recently in Brazil, this work analyzes the situations of vulnerability risk areas on the Northern Coast of São Paulo. The situation analyzed refers to the effects of the implementation of large infrastructure projects related to oil and gas on the occupation of risk areas to landslides and flooding, besides considering the technological risks inherent in these megaprojects. Figure 1 show the technological and environmental risks in three regions of Brazilian Southeast coast ? detailed to Northern coast of São Paulo

Multiscale approaches to analyse risks and vulnerabilities in the coastal zone (Brazil).

The objectives of this work were: (i) identified the risk areas of landslides, flooding and sea level rise and social vulnerabilities in different scales of analysis; (ii) analyse the risk perception of people living in this risk areas; (iii) found a common dialogues between sciences and communities to inform policy and decision-making in the different socioeconomic sectors