Fundamenta Informaticae - Volume 68, issue 4

Authors: Bocharov, Igor | Lukin, Pavel

Article Type: Research Article

Abstract: The article discusses an application of Kullback-Leibler divergence to the recognition of speech signals and suggests three algorithms implementing this divergence criterion: correlation algorithm, spectral algorithm and filter algorithm. Discussion covers an original approach to the problem of speech variability and is illustrated with results of experimental speech signal modeling. The article gives a number of recommendations on the choice of appropriate model parameters and provides a comparison to some other methods of …speech recognition. Show more

Keywords: speech recognition, speech variability, information divergence

Citation: Fundamenta Informaticae, vol. 68, no. 4, pp. 303-313, 2005

Authors: Lin, Chih-Yang | Chang, Chin-Chen | Lin, Chia-Chen

Article Type: Research Article

Abstract: Density-based clustering can identify arbitrary data shapes and noises. Achieving good clustering performance necessitates regulating the appropriate parameters in the density-based clustering. To select suitable parameters successfully, this study proposes an interactive idea called GADAC to choose suitable parameters and accept the diverse radii for clustering. Adopting the diverse radii is the original idea employed to the density-based clustering, where the radii can be adjusted by the genetic algorithmto cover the clusters …more accurately. Experimental results demonstrate that the noise and all clusters in any data shapes can be identified precisely in the proposed scheme. Additionally, the shape covering in the proposed scheme is more accurate than that in DBSCAN. Show more

Keywords: Clustering algorithms, genetic algorithms, DBSCAN

Citation: Fundamenta Informaticae, vol. 68, no. 4, pp. 315-331, 2005

Authors: Poranen, Timo

Article Type: Research Article

Abstract: The optimal linear arrangement problem is defined as follows: given a graph G, find a linear ordering for the vertices of G on a line such that the sum of the edge lengths is minimized over all orderings. The problem is NP-complete and it has many applications in graph drawing and in VLSI circuit design. We introduce a genetic hillclimbing algorithm for the optimal linear arrangement problem. We compare the quality of the solutions and running times …of our algorithm to those obtained by simulated annealing algorithms. To obtain comparable results, we use a benchmark graph suite for the problem. Our experiments show that there are graph classes for which the optimal linear arrangement problem can be efficiently approximated using our genetic hillclimbing algorithm but not using simulated annealing based algorithms. For hypercubes, binary trees and bipartite graphs, the solution quality is better and the running times are shorter than with simulated annealing algorithms. Also the average results are better. On the other hand, there also are graph classes for which simulated annealing algorithms work better. Show more

Keywords: Genetic algorithm, optimization, hillclimbing, optimal linear arrangement problem

Citation: Fundamenta Informaticae, vol. 68, no. 4, pp. 333-356, 2005

Authors: Qi, Guilin | Milligan, Peter | Sage, Paul

Article Type: Research Article

Abstract: Incidence calculus is a probabilistic logic which possesses both numerical and symbolic approaches. However, Liu in [5] pointed out that the original incidence calculus had some drawbacks and she established a generalized incidence calculus theory (GICT) based on Łukasiewicz's three-valued logic to improve it. In a GICT, an incidence function is defined to relate each proposition ϕ in the axioms of the theory to a set of possible worlds in which ϕ has truth value true. …But the incidence function only represents those absolute true states of propositions, so it can not deal with the uncertain states. In this paper, we use two incidence functions i_* and i^* to relate the axioms to the sets of possible worlds. For an axiom ϕ, i_* (ϕ) is to be thought of as the set of possible worlds in which ϕ has truth value true, while i^* (ϕ) is the set of possible worlds in which ϕ is true or undeterminable. Since i^* can represent the undeterminable state, our newly defined theory is more efficient to handle vague information than GICT. Show more

Keywords: probabilistic logic, incidence calculus, basic incidence assignment

Citation: Fundamenta Informaticae, vol. 68, no. 4, pp. 357-378, 2005

Authors: Sydow, Marcin

Article Type: Research Article

Abstract: The World Wide Web with its billions of hyperlinked documents is a huge and important resource of information. There is a necessity of filtering this information. Link analysis of the Web graph turned out to be a powerful tool for automatically identifying authoritative documents. One of the best examples is the PageRank algorithm used in Google [1] to rank search results. In this paper we extend the model underlying the PageRank algorithm by incorporating …"back button" usage modeling in order to make the model less simplistic. We explain the existence and uniqueness of the ranking induced by the extended model. We also develop and implement an efficient approximation method for computing the novel ranking and present succesful experimental results made on 80- and 50- million page samples of the real Web. Show more

Keywords: Web Information Retrieval, Link Analysis, PageRank, Back Button Modeling

Citation: Fundamenta Informaticae, vol. 68, no. 4, pp. 379-398, 2005

Authors: Wu, Hsien-Chu | Hwang, Min-Shiang | Liu, Chia-Hsin

Article Type: Research Article

Abstract: Password authentication, which is widely used for authenticated method, also is important protocol by requiring a username and password before being allowed access to resources. In 2001, Lin et al. proposed the optimal strong-password authentication protocol, called (OSPA) which is a one-time password method by verifying with the different verifier every time for affirming its identity. However, Chen-Ku and Tsuji-Shimizu pointed respectively out that OSPA is vulnerable to the stolen-verifier attack and impersonation …attack. In this paper, we shall propose the improved protocol secure against the known attacks to enhance the security Show more

Keywords: Authentication, cryptography, hash function, password

Citation: Fundamenta Informaticae, vol. 68, no. 4, pp. 399-406, 2005