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On definability in the nondeterministic information system. (English) Zbl 0677.68110

Summary: We introduce several approximation operations \b{E}\({}_ i\) in the space (U,E), where E is a cover of a set U. In particular when E is a partition of U, they are reduced to the operations \b{X} and \(\bar X\) of Pawlak. We investigate the properties of the operations \b{E}\({}_ i\), the relations among them and their connections with set-theoretical oprations \(\cup\), -, \(\cap\). We examine the notions of definability with respect to the introduced operations. We apply the results obtained to the nondeterministic information systems, but the scope of applications may be extended.

MSC:

68P20 Information storage and retrieval of data
93A99 General systems theory
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