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Content available remote Reconstruction of Concurrent System Models Described by Decomposed Data Tables
EN
This paper deals with reconstruction of net models of concurrent systems described by information systems changing in time. Constructed net models have the form of coloured Petri nets. Resulting nets are constructed on the basis of decomposed information systems. In many practical cases, a description of modelled systems changes in time. New knowledge about structures and behaviours of systems appears. When new descriptions appear, the net models should be changed taking into consideration the new knowledge. An approach to reconstruction of net models is here presented. One of many possible cases is considered, i.e., when the new global state of the modelled system appears. The ability to compute reducts and components of a new information system, being a new description of a modelled system, in an efficient way is important for reconstruction. Therefore, some propositions and corollaries useful to compute reducts of a new information system on the basis of reducts of an old information system are given. These propositions and corollaries are the basis to formulate algorithms for computing new reducts and components. Moreover, a way to determine the cost of the reconstruction of a net model is given. The cost of the reconstruction is treated as the cost of adding new functional modules, communication lines or their modifications. The discussed approach to model reconstruction extends and refines that proposed by Z. Suraj in 1998. An example is given in this paper to illustrate the presented idea.
2
Content available remote On Modal and Fuzzy Decision Logics Based on Rough Set Theory
EN
Some modal decision logic languages are proposed for knowledge representation in data mining through the notions of models and satisfiability. The models are collections of data tables consisting of a finite set of objects described by a finite set of attributes. Some relationships may exist between data tables in a collection and the modalities of our languages are interpreted with respect to these relations in Kripkean style semantics. The notion of fuzzy decision logic is also reviewed and combined with the modal decision logic. The combined logic is shown to be useful in the representation of fuzzy sequential patterns.
3
Content available remote A possibilistic decision logic with applications
EN
In this paper, we investigate a knowledge representation formalism in the context of fuzzy data tables. A possibilistic decision logic incorporating linguistic terms is proposed for representing and reasoning about knowledge in fuzzy data tables. Two applications based on the logic are described. The first is the extraction of fuzzy rules from general fuzzy data tables. In this application, the knowledge in the tables may be made explicit by the formulas of the logic or used implicitly in decision-making. The second is for the fuzzy quantization problem of precise data tables. It can be viewed as a special case of the first, however, due to some special properties of the problem, a polynomial time rule extraction process can be obtained. Finally, the relationship of the logic with some works for handling uncertain information in data tables is also discussed.
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