Information retrieval systems depend on Boolean queries. Proposed evolution of Boolean queries should increase the performance of the information retrieval system. Information retrieval systems quality are measured in terms of two different criteria, precision and recall. Evolutionary techniques are widely applied for optimization tasks in different areas including the area of information retrieval systems. In information retrieval applications both criteria have been combined in a single scalar fitness function by means of a weighting scheme 'harmonic mean'. Usage of genetic algorithms in the Information retrieval, especially in optimizing a Boolean query, is presented in this paper. Influence of both criteria, precision and recall, on quality improvement are discussed as well.
It has been known for a long time that for bootstrapping the distribution of the extremes under the traditional linear normalization of a sample consistently, the bootstrap sample size needs to be of smaller order than the original sample size. In this paper, we show that the same is true if we use the bootstrap for estimating a central, or an intermediate quantile under power normalization. A simulation study illustrates and corroborates theoretical results.
The contribution of woodiniee (Apodemus sylvaticus), yellow-necked mice (Apodemus flavicollis) and bank voles (Clethrionomys glareolus) was compared in a focus of Lyme borreliosis in Switzerland during a 7 months’ study. All three species of mice and one species of shrews (Sorex araneus) were shown parasitized by infected Ixodes ricinus immatures. About 14% of larvae and 50% of nymphs collected on small mammals were infected with B. burgdorferi. Spirochetes were isolated from blood of 3 woodmice and one yellow-necked mouse. The infectious status of rodents was estimated by tick xenodiagnosis. Prevalence of infected rodents ranged from 20% to 44%. Mice presented a higher potential infectivity than voles. The prevalence of infected rodents showed a seasonal variation.