GRASP and statistical bounds for heuristic solutions to combinatorial problems

The quality of a heuristic solution to a NP-hard combinatorial problem is hard to assess. A few studies have advocated and tested statistical bounds as a method for assessment. These studies indicate that statistical bounds are superior to the more widely known and used deterministic bounds. However, the previous studies have been limited to a few metaheuristics and combinatorial problems and, hence, the general performance of statistical bounds in combinatorial optimization remains an open question. This work complements the existing literature on statistical bounds by testing them on the metaheuristic Greedy Randomized Adaptive Search Procedures (GRASP) and four combinatorial problems. Our findings confirm previous results that statistical bounds are reliable for the p-median problem, while we note that they also seem reliable for the set covering problem. For the quadratic assignment problem, the statistical bounds has previously been found reliable when obtained from the Genetic algorithm whereas in this work they found less reliable. Finally, we provide statistical bounds to four 2-path network design problem instances for which the optimum is currently unknown.

Lanseringen och etableringen av ett socialt problem : En analys av debatten om ledarkulturen inom svensk landslagsgymnastik i Dagens Nyheter 2012–2013

The launching and establishment of a social problem: An analysis of the debate on Swedish national level gymnastics in Dagens Nyheter 2012-2013 In 2012 Sweden’s largest daily newspaper, Dagens Nyheter, published a number of articles on the state of affairs in Swedish national level gymnastics. In these articles, ex-gymnasts, coaches, parents and physicians stepped forward and testified about recurrent wrongdoings and abuse against young (particularly) female gymnasts. In response to the criticism, the accused coaches and representatives of the Swedish Gymnastics Federation downsized or dismissed the criticism as inaccurate. This being said, and using discursive psychology and a qualitative design, this article sheds light upon this debate – by viewing it as a struggle between a hegemonic discourse of ”the goodness” of sports, on the one hand, a number of unfavorable and negative testimonies of the state of affairs in Swedish national level gymnastics on the other. More concretely, this struggle has been analyzed with regard to the discursive and rhetoric resources the involved parties’ used to pursue their claims about the state of affairs in Swedish national level gymnastics and the impact these resources had for their credibility and legitimacy. Questions were: Who is entitled ”to spell out” their view on the state of affairs within Swedish national level gymnastics? What is mediated and how? How are descriptions and accounts about reality constructed as credible and factual? It is concluded that social problems are launched via co-production; in this process, the gymnastics community, the research community, single individuals, and the media – were co-actors.