Fundamenta Informaticae - Volume 76, issue 1-2

Authors: Saha, Suman | Murthy, C.A. | Pal, Sankar K.

Article Type: Research Article

Abstract: Combining the results of a number of individually trained classification systems to obtain a more accurate classifier is a widely used technique in pattern recognition. In this article, we have introduced a rough set based meta classifier to classify web pages. The proposed method consists of two parts. In the first part, the output of every individual classifier is considered for constructing a decision table. In the second part, rough set attribute reduction and rule generation …processes are used on the decision table to construct a meta classifier. It has been shown that (1) the performance of the meta classifier is better than the performance of every constituent classifier and, (2) the meta classifier is optimal with respect to a quality measure defined in the article. Experimental studies show that the meta classifier improves accuracy of classification uniformly over some benchmark corpora and beats other ensemble approaches in accuracy by a decisive margin, thus demonstrating the theoretical results. Apart from this, it reduces the CPU load compared to other ensemble classification techniques by removing redundant classifiers from the combination. Show more

Keywords: Text classification, Rough set, Meta classifier

Citation: Fundamenta Informaticae, vol. 76, no. 1-2, pp. 171-187, 2007

Authors: Tarasyuk, Igor V.

Article Type: Research Article

Abstract: In the last decades, a number of stochastic enrichments of process algebras was constructed to allow one for specification of stochastic processes within the well-developed framework of algebraic calculi. In [40], a continuous time stochastic extension of finite Petri box calculus (PBC) was proposed called sPBC. The algebra sPBC has interleaving semantics due to the properties of continuous time distributions. At the same time, PBC has step semantics, and it could be natural to propose its …concurrent stochastic enrichment. We construct a discrete time stochastic extension dtsPBC of finite PBC. A step operational semantics is defined in terms of labeled transition systems based on action and inaction rules. A denotational semantics is defined in terms of a subclass of labeled discrete time stochastic Petri nets (LDTSPNs) called discrete time stochastic Petri boxes (dts-boxes). A consistency of both semantics is demonstrated. In addition, we define a variety of probabilistic equivalences that allow one to identify stochastic processes with similar behaviour which are differentiated by too strict notion of the semantic equivalence. The interrelations of all the introduced equivalences are investigated. Show more

Keywords: Stochastic Petri nets, stochastic process algebras, Petri box calculus, discrete time, transition systems, operational semantics, dts-boxes, denotational semantics, empty loops, probabilistic equivalences

Citation: Fundamenta Informaticae, vol. 76, no. 1-2, pp. 189-218, 2007