Fundamenta Informaticae - Volume 61, issue 3-4

Authors: Bergstra, Jan A. | Middelburg, Cornelis A.

Article Type: Research Article

Abstract: We propose a process algebra obtained by adapting the process algebra with continuous relative timing from Baeten and Middelburg [Process Algebra with Timing, Springer, 2002, Chap. 4] to spatially located actions. This process algebra makes it possible to deal with the behaviour of systems with a known time-dependent spatial distribution, such as protocols transmitting data via a mobile intermediate station. It is a reformulation of the real space process algebra from Baeten and Bergstra [Formal Aspects …of Computing, 5, 1993, 481–529] in a setting with urgent actions. This leads to many simplifications. Show more

Keywords: process algebra, continuous relative timing, spatially located actions, distributed systems, state operator, maximal progress, asynchronous communication, urgent actions

Citation: Fundamenta Informaticae, vol. 61, no. 3-4, pp. 183-211, 2004

Authors: Chan, Yung-Kuan | Wang, Her-Fa | Lee, Chin-Fan

Article Type: Research Article

Abstract: This paper presents a refined VQ-based image compression method which modifies the traditional VQ-based image compression method. The refined VQ-based image compression method further lossless encodes the compression data which is generated by the traditional VQ-based image compression method into a set of compression codes. The index image generated by the refined method is a contracted image of the compressed image, which can be used as the preview of the compressed image on image management. Although …the PSNRs of the reconstructed images that are decoded by the refined VQ-based image compression method and the traditional VQ-based image compression method are the same, the refined VQ-based image compression method provides a better storage efficiency. Show more

Keywords: VQ-based compression method, LBG algorithm, K-means clustering, JPEG compression method, JBIG compression method

Citation: Fundamenta Informaticae, vol. 61, no. 3-4, pp. 213-221, 2004

Authors: Georgescu, Irina

Article Type: Research Article

Abstract: This paper is concerned with consistency properties for fuzzy consumers. We introduce the consistency conditions Fα, Fβ, Fδ as fuzzy forms of Sen's properties alpha, beta and delta. Other consistency conditions are also studied: Fα2, Fβ(+), Fγ2 and FPI. The main results are: (1) A fuzzy consumer verifies Fα, Fβ if and only if the congruence axiom WFCA holds; (2) If h is a normal fuzzy consumer then Fδ holds if and only if the associated fuzzy preference relation R is quasi-transitive; (3) A fuzzy consumer is normal if and only if conditions Fα2, Fγ2 hold.

Keywords: fuzzy relation, fuzzy consumers, fuzzy revealed preference

Citation: Fundamenta Informaticae, vol. 61, no. 3-4, pp. 223-245, 2004

Authors: Janin, David | Lenzi, Giacomo

Article Type: Research Article

Abstract: In 1970 [26], in Weakly definable relations and special automata, Math. Log. and Found. of Set Theory, pp 1-23, Rabin shows that a language is recognizable by a tree automaton with Büchi like infinitary condition if and only if it is definable as the projection of a weakly definable language. In this paper, we refine this result characterizing such languages as those definable in the monadic Σ2 level of the quantifier alternation depth hierarchy of …monadic second order logic (MSO). This new result also contributes to a better understanding of the relationship between the quantifier alternation depth of hierarchy of MSO and the fixpoint alternation depth hierarchy of the mu-calculus: it shows that the bisimulation invariant fragment of the monadic Σ2 level equals the νμ-level of the mu-calculus hierarchy. Show more

Citation: Fundamenta Informaticae, vol. 61, no. 3-4, pp. 247-265, 2004

Authors: Kozera, Ryszard

Article Type: Research Article

Abstract: We discuss the problem of estimating the trajectory of a regular curve γ:[0,T]→Rn and its length d(γ) from an ordered sample of interpolation points Qm ={γ(t0 ),γ(t1 ),...,γ(tm )}, with tabular points ti 's unknown, coined as interpolation of unparameterized data. The respective convergence orders for estimating γ and d(γ) with cumulative chord piecewise-quartics are established for different types of unparameterized data including egr-uniform and more-or-less uniform samplings. The latter extends previous results on cumulative …chord piecewise-quadratics and piecewise-cubics. As shown herein, further acceleration on convergence orders with cumulative chord piecewise-quartics is achievable only for special samplings (e.g. for ε-uniform samplings). On the other hand, convergence rates for more-or-less uniform samplings coincide with those already established for cumulative chord piecewise-cubics. The results are experimentally confirmed to be sharp for m large and n=2,3. A good performance of cumulative chord piecewise-quartics extends also to sporadic data (m small) for which our asymptotical analysis does not apply directly. Show more

Keywords: interpolation, unparameterized data, cumulative chord piecewise-quartics, curve and length estimation, orders of approximation

Citation: Fundamenta Informaticae, vol. 61, no. 3-4, pp. 267-283, 2004

Authors: Kozera, Ryszard | Noakes, Lyle

Article Type: Research Article

Abstract: Cumulative chord C1 piecewise-cubics, for unparameterized data from regular curves in Rn , are constructed as follows. In the first step derivatives at given ordered interpolation points are estimated from ordinary (non-C1 ) cumulative chord piecewise-cubics. Then Hermite interpolation is used to generate a C1 piecewise-cubic interpolant. Theoretical estimates of orders of approximation are established, and their sharpness verified through numerical experiments. Good performance of the interpolant is also confirmed …experimentally on sparse data. Show more

Keywords: interpolation, unparameterized data, cumulative chord, curve and length estimation, orders of approximation

Citation: Fundamenta Informaticae, vol. 61, no. 3-4, pp. 285-301, 2004

Authors: Skarbek, Władysław | Kucharski, Krzysztof | Bober, Mirosław

Article Type: Research Article

Abstract: The complete theory for Fisher and dual discriminant analysis is presented as the background of the novel algorithms. LDA is found as composition of projection onto the singular subspace for within-class normalised data with the projection onto the singular subspace for between-class normalised data. The dual LDA consists of those projections applied in reverse order. The experiments show that using suitable composition of dual LDA transformations gives as least as good results as recent …state-of-the-art solutions. Show more

Keywords: linear discriminant analysis, dual linear discriminant analysis, feature extraction, face recognition, face descriptor

Citation: Fundamenta Informaticae, vol. 61, no. 3-4, pp. 303-334, 2004

Authors: Skarbek, Władysław | Sikora, Thomas | Galinski, Grzegorz

Article Type: Research Article

Abstract: Several fast filtering attributes are analysed for vector interval (cell) pruning while querying the vector approximation file. Beside distance range, sum and median features their deviation forms are introduced. Range and K-NN queries are considered and appropriate acceptance intervals are designed. The impact of feature space dimensionality on index design is discussed, too.

Keywords: multidimensional indexing, index filtering, vector interval, vector approximation file

Citation: Fundamenta Informaticae, vol. 61, no. 3-4, pp. 335-349, 2004

Authors: Werner, Matthias | Popova-Zeugmann, Louchka | Richling, Jan

Article Type: Research Article

Abstract: Times and priorities are important concepts that are frequently used to model real-world systems. Thus, there exist extensions for Petri nets which allow to model times and priorities. In contrast, many proof techniques are based on classical (time-less and priority-less) Petri nets. However, this approach fails frequently for timed and prioritized Petri nets. In this paper, we present an approach to prove non-reachability in a Priority Duration Petri net. We use for this proving technique a …state equation as well as conditions for firing that include a priority rule and a maximal step rule. Our approach leads to a system of equations and inequalities, which provide us with a sufficient condition of non-reachability. We demonstrate the application of our approach with an example. Show more

Keywords: priority duration Petri net, state equation, non-reachability

Citation: Fundamenta Informaticae, vol. 61, no. 3-4, pp. 351-368, 2004

Authors: Wnukowicz, Karol

Article Type: Research Article

Abstract: The paper presents new methods for image content indexing by the use of color temperature feature. A descriptor for dominant color temperature is introduced, for which two types of queries are discussed: a query by color temperature value and a query by example. Finally, a data structure for search optimized storage of the introduced descriptor is proposed and evaluated.

Keywords: image indexing, color temperature

Citation: Fundamenta Informaticae, vol. 61, no. 3-4, pp. 369-378, 2004

Authors: Yu, Yuan-Hui | Chang, Chin-Chen

Article Type: Research Article

Abstract: This paper presents an effective and efficient method for solving scenery image segmentation by applying the SVMs methodology. Scenery image segmentation is regarded as a data classification problem, and is effectively answered by the proposed method in this paper. Using the model selection in our system architecture, our system is relatively simple compared to other conventional heuristic image segmentation approaches yet demonstrates promising classification results.

Keywords: SVMs, SVM-based classification, scenery image segmentation, model selection,

Citation: Fundamenta Informaticae, vol. 61, no. 3-4, pp. 379-388, 2004

Authors: Hwang, Min-Shiang | Lo, Jung-Wen | Liu, Chia-Hsin

Article Type: Research Article

Abstract: The denial-of-service attack, a malicious client executes a key agreement protocol simultaneously many times to exhaust the server's memory or computing resource and to interfere the honest client connecting with the server. It is a serious problem in the key agreement protocol. A key agreement protocol which resists to the storage-exhaustion and the CPU-exhaustion attack was firstly proposed by Hiros-Matsuura. However, their protocol is not efficient enough during the weak key validation. Our proposed protocol modifies …the weak key validation and avoids the unnecessary heavy computation to enhance the resistance of the denial-of-service attack. The most important contributions of our protocol are not only efficiently to resist CPU-exhaustion and memory-exhaustion attacks but also prevent bandwidth consumption. Show more

Keywords: cryptography, denial-of-service, Diffie-Hellman, key agreement, security

Citation: Fundamenta Informaticae, vol. 61, no. 3-4, pp. 389-398, 2004