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2 International Journal of Applied Mathematics and Computer Science

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Optimization of the maximum likelihood estimator for determining the intrinsic dimensionality of high-dimensional data

Karbauskaitė R., Dzemyda G.

International Journal of Applied Mathematics and Computer Science

2015

Vol. 25, no. 4

895--913

One of the problems in the analysis of the set of images of a moving object is to evaluate the degree of freedom of motion and the angle of rotation. Here the intrinsic dimensionality of multidimensional data, characterizing the set of images, can be used. Usually, the image may be represented by a high-dimensional point whose dimensionality depends on the number of pixels in the image. The knowledge of the intrinsic dimensionality of a data set is very useful information in exploratory data analysis, because it is possible to reduce the dimensionality of the data without losing much information. In this paper, the maximum likelihood estimator (MLE) of the intrinsic dimensionality is explored experimentally. In contrast to the previous works, the radius of a hypersphere, which covers neighbours of the analysed points, is fixed instead of the number of the nearest neighbours in the MLE. A way of choosing the radius in this method is proposed. We explore which metric—Euclidean or geodesic—must be evaluated in the MLE algorithm in order to get the true estimate of the intrinsic dimensionality. The MLE method is examined using a number of artificial and real (images) data sets.

Mean Squared Load Criteria for Scheduling Independent Tasks

Dzemyda G.

International Journal of Applied Mathematics and Computer Science

1999

Vol. 9, no 4

939-954

Results of this paper extend the set of criteria which characterize the scheduling quality as well as the set of possible scheduling strategies. A new view on the minimum makespan criterion is presented in terms of the mean squared load of processing units. This leads in turn to the development of new scheduling algorithms. The interaction between processes of minimizing the new criteria and the maximum finishing time (makespan of the schedule) was discovered. We show the possibility of minimizing the maximum finishing time by minimizing the new criteria that characterize the mean squared load of processing units. Moreover, the optimal workload of processing units determined with the use of the proposed criteria is usually smoother (more balanced) than that found for traditional ones.