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Vol: 56(70) No: 3 / September 2011

The Decision Rules Synthesis Based on Similarity Relation
Vladimir Brtka
Department of Computer Science, University of Novi Sad, Technical Faculty “Mihajlo Pupin”, Djure Djakovica bb, 23000 Zrenjanin, Serbia, phone: (+381) 23 550 515, e-mail: brtkav@gmail.com
Eleonora Brtka
Department of Computer Science, University of Novi Sad, Technical Faculty “Mihajlo Pupin” , Djure Djakovica bb, 23000 Zrenjanin, Serbia, e-mail: brtka@sbb.rs
Visnja Ognjenovic
Department of Computer Science, University of Novi Sad, Technical Faculty “Mihajlo Pupin”, Djure Djakovica bb, 23000 Zrenjanin, Serbia, e-mail: visnjaognjenovic@gmail.com
Ivana Berkovic
Department of Computer Science, University of Novi Sad, Technical Faculty “Mihajlo Pupin”, Djure Djakovica bb, 23000 Zrenjanin, Serbia, e-mail: berki@.sbb.rs


Keywords: rough sets theory, indiscernibility, similarity, decision rules

Abstract
This paper deals with data analyses based on the rough sets theory when table organized data is available. The application of the rough sets theory enables synthesis of the decision rules in the readable If Then form. Unlike the standard approach to decision rules synthesis when the whole data table is used, proposed approach is focused to a single element of the data table. Similarity classes are formed by similarity relation for each element. Local and global similarity relations have been described as well as the process of the aggregation of local similarities. Instead of the partition, as is the case when equivalence based indiscernibility relation is used, we have similarity classes, so decision rules are synthesized according to each similarity class separately in a standard way by rough sets toolkit Rosetta. This enables an insight to the properties of each similarity class. Possible advantage of the proposed approach is that a single element is not evaluated by its own properties only, but by the properties of entire similarity class to which the element belongs. An experiment was conducted on small data sample available via Internet ftp protocol. Generated decision rules can be analyzed by different techniques, by domain experts. Results show how the technique based the proposed approach can be implemented and used in various enterprises.

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