| 1. |
- Hammer, Peter L., et al.
(författare)
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Maximum weight archipelago subgraph problem
- 2014
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Ingår i: Annals of Operations Research. - : Springer Science and Business Media LLC. - 0254-5330 .- 1572-9338. ; 217:1, s. 253-262
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Tidskriftsartikel (refereegranskat)abstract
- This paper is devoted to a new problem of combinatorial optimization. The problem is called Maximum Weight Archipelago Subgraph Problem (MWASP). Archipelago is a signed graph such that the negative edges connect the components of the graph of the positive edges. The new problem is to find a subset of edges in a weighted signed graph such that (i) if the edges of the subset are deleted from the graph then the remaining graph is an archipelago; and (ii) the subset has minimal total weight among the subsets having property (i). The problem is NP-complete, however a polynomial algorithm is provided to obtain the maximal weight of an edge what is still necessary to delete. The problem MWAP is used to analyze the relation of the blue chips of the Dow Jones Index.
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| 2. |
- Bohman, Samuel, 1975-
(författare)
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Web Applications for Large-Scale Decision Support : Preference Elicitation, Modeling and Visualization
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis addresses the lack of effective and efficient technology design in current e-participation research by investigating two approaches that yet have not been explored to any great extent in the literature: decision science and data visualization. It is concerned with the problem of how to combine techniques from these two fields to achieve decision support in the context of e-participation; from preference elicitation and modeling to data analysis, visualization and final recommendations, such that it can provide value to practitioners. The work was carried out in two separate research projects, but which shared a common research strategy: to develop, demonstrate, and evaluate e-participation technologies in real-life settings. The first project was a pilot designed to provide European universities with a web-based e-participation platform to empower students in the Bologna Process. Thirteen universities in Europe participated as end-users of the platform. Using a mixed methods research design, the results showed that ICT is poorly conceptualized in e-participation research and practice, typically conceived informally and simply as tools, independent of the political and social context within which they are developed and used. With regard to sociotechnical challenges in e-participation, the results confirm much of previous research that has underlined the prevalence of technological determinism, institutional resistance, privacy and trust issues, among many other factors. In the second project we developed a decision analytic framework for structuring, evaluating, and analyzing stakeholder conflicts in land-use planning. The Municipality of Upplands Väsby in Stockholm, Sweden, participated as a trial. Using agile design principles and methods we implemented the framework as a prototype spatial decision support system using the R programming language. Our prototype shows that a combination of decision science and data visualization has the potential to become a powerful tool in the hands of governments to enable members of society to identify where their differences really matter and where they are unimportant, thus providing structure and new insight to democratic debate. Furthermore, we believe it has the potential to alleviate some of the barriers and limitations associated with traditional methods of community engagement, including distance and time constraints, issues of scale, and high costs.
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| 3. |
- Majlender, Peter
(författare)
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A note on the convexity assumption of possibilistic correlation
- 2012
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Ingår i: Applied Mathematics Letters. - : Elsevier BV. - 0893-9659 .- 1873-5452. ; 25:4, s. 672-675
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Tidskriftsartikel (refereegranskat)abstract
- In 2005, 2005, Carlsson, Fuller and Majlender introduced a measure of possibilistic correlation of fuzzy numbers A and B by their joint possibility distribution C as an average degree of interaction between the gamma-level sets of A and B as compared to their individual dispersions. They proved that this possibilistic correlation coefficient can never exceed 1 in absolute value, if all gamma-level sets of the joint possibility distribution C are convex. In this communication, we shall formulate a special class of joint possibility distributions with non-convex gamma-level sets, for which the correlation coefficient can take values outside the interval [-1, 1]. in particular, this result will show that the assumption about the convexity of the level sets of C is essential for the possibilistic correlation to be bounded by the interval [-1, 1].
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| 4. |
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| 5. |
- Zacarias, Orlando P., et al.
(författare)
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Comparison of infant malaria incidence in districts of Maputo province, Mozambique
- 2011
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Ingår i: Malaria Journal. - : Springer Science and Business Media LLC. - 1475-2875. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Background: Malaria is one of the principal health problems in Mozambique, representing 48% of total external consultations and 63% of paediatric hospital admissions in rural and general hospitals with 26.7% of total mortality. Plasmodium falciparum is responsible for 90% of all infections being also the species associated with most severe cases. The aim of this study was to identify zones of high malaria risk, showing their spatially and temporal pattern. Methods: Space and time Poison model for the analysis of malaria data is proposed. This model allows for the inclusion of environmental factors: rainfall, temperature and humidity as predictor variables. Modelling and inference use the fully Bayesian approach via Markov Chain Monte Carlo (MCMC) simulation techniques. The methodology is applied to analyse paediatric data arising from districts of Maputo province, Mozambique, between 2007 and 2008. Results: Malaria incidence risk is greater for children in districts of Manhica, Matola and Magude. Rainfall and humidity are significant predictors of malaria incidence. The risk increased with rainfall (relative risk - RR: .006761, 95% interval: .001874, .01304), and humidity (RR: .049, 95% interval: .03048, .06531). Malaria incidence was found to be independent of temperature. Conclusions: The model revealed a spatial and temporal pattern of malaria incidence. These patterns were found to exhibit a stable malaria transmission in most non-coastal districts. The findings may be useful for malaria control, planning and management.
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