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Theory Of Skyline Queries

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Many attempts have been made towards developing optimized algorithms and introduction of several models for skyline queries. Skyline queries had been studied as the maximum vectors before Borzsony and colleagues [23] introduced skyline queries for database applications. Various algorithms are provided for skyline computations, including calculation of the progressive skyline using auxiliary structures, the nearest neighbor algorithm for processing the skyline query, the branch and bound skyline (BBS) algorithm, the sort-filter skyline (SFS) algorithm that exploits pre-arranged lists, and linear erase-sorting (LESS) algorithm for the skyline. Recently, there has been a growing interest in addressing the problem of "large dimensions" for …show more content…

In [28], it is shown that the proposed method is not correct. Sharifzadeh and colleagues [29] have proposed another version of the method that eliminates the flaws of the previous version, but it is computationally costly. Other methods for calculating skyline have been suggested as well. A multi-objective optimized process for skyline has been presented based on the genetic algorithm by Özyer et al. [30]. Fuzzy skyline has been proposed to make the skyline more flexible. In particular, fuzzy skyline in [31] is considered and a flexible overcome relation is provided. This relationship makes it possible to extend skyline with points that are not highly dominated by any other points (even if they are strongly dominated). Yet, other methods arise to improve the skyline. A variety of fuzzy skyline methods are studied in [32]. In the paper, five incentives are raised to fuzzify the skyline. The first motivation is to refine the skyline with the introduction of a sequence of points to find the best skyline points. The second is to make the skyline more flexible. This means that where points' conditions are close to the skyline points, they are also considered as members of the skyline. In the third case, the skyline can become easier with different methods. For example, by

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