Fundamenta Informaticae - Volume 58, issue 2

Authors: Alhazov, Artiom | Martín-Vide, Carlos | Pan, Linqiang

Article Type: Research Article

Abstract: P systems are parallel molecular computing models based on processing multisets of objects in cell-like membrane structures. Recently, Petr Sosík has shown that a semi-uniform family of P systems with active membranes and 2-division is able to solve the PSPACE-complete problem QBF-SAT in linear time; he has also conjectured that the membrane dissolving rules of the (d) type may be omitted, but probably not the (f) type rules for non-elementary membrane division. In this paper, we …partially confirm the conjecture proving that dissolving rules are not necessary. Moreover, the construction is now uniform. It still remains open whether or not non-elementary membrane division is needed. Show more

Keywords: Membrane computing, P system, PSPACE-complete problem, QBF-SAT problem

Citation: Fundamenta Informaticae, vol. 58, no. 2, pp. 67-77, 2003

Authors: Bělohlávek, Radim

Article Type: Research Article

Abstract: In fuzzy set theory, similarity phenomenon is approached using so-called fuzzy equivalence relations. An important role in fuzzy modeling is played by similarity-based closure (called also the extensional hull). Intuitively, the degree to which an element x belongs to a similarity-based closure of a fuzzy set A is the degree to which it is true that there is an element y in A which is similar to x. In this paper, we show a basic relationship …between similarity-based closure and metric closure, and provide an axiomatic characterization of the operation of a similarity-based closure. Show more

Keywords: similarity, fuzy equivalence, fuzzy closure operator

Citation: Fundamenta Informaticae, vol. 58, no. 2, pp. 79-91, 2003

Authors: Chan, Chao-Wen | Chang, Chin-Chen

Article Type: Research Article

Abstract: More and more sensitive image data is generated and transmitted over the Internet. To protect them, a new image hiding scheme is proposed in this paper. The proposed scheme is based on steganography, the principle of human visibility, and interpolating polynomials. The scheme assumes the capacity of a cover image to its hypothetic upper bound size of a cover image in the general image hiding schemes. Moreover, the scheme introduces MSB channel of image hiding over …which we can transmit secret information of text type. Show more

Keywords: DCT, frequency domain, image hiding, interpolating polynomials, steganorgraphy, torus automorphism

Citation: Fundamenta Informaticae, vol. 58, no. 2, pp. 93-104, 2003

Authors: Kłlopotek, Mieczysław

Article Type: Research Article

Abstract: Bayesian networks have many practical applications due to their capability to represent joint probability distribution over many variables in a compact way. Though there exist many algorithms for learning Bayesian networks from data, they are not satisfactory because the learned networks usually are not suitable directly for reasoning as they need to be transformed to some other form (tree, polytree, hypertree) statically or dynamically, and this transformation is not trivial [25]. So far only a restricted …class of very simple Bayesian networks: trees and poly-trees are directly applicable in reasoning. This paper defines and explores a new class of networks: the Structured Bayesian Networks. Two methods of reasoning are outlined for this type of networks. Possible methods of learning from data are indicated. Similarity to hierarchical networks is pointed at. Show more

Keywords: Bayesian networks, reasoning, structured networks, hierarchical networks

Citation: Fundamenta Informaticae, vol. 58, no. 2, pp. 105-137, 2003

Authors: Kou, Hui | Luo, Maokang

Article Type: Research Article

Abstract: A dependence space is an ordered pair consisting of a nonempty finite set and a congruence on its boolean lattice, and is viewed as a general model to deal with the indiscernibility-type incompleteness of information in rough set analysis. In this paper we consider the question when a dependence space can be locally approximated by a approximation space. We introduce a concept of (weakly) local approximation spaces and establish several important relationships among equivalences, reducts, and …sub-reducts with respect to (weakly) local approximation spaces. It is shown that a dependence space is a local approximation space if and only if it is locally reducible if and only if the closure lattice generated by the dependence space is an atomic lattice. This result also gives a partial solution to an open problem posed by M. Novotný. Show more

Keywords: dependence space, congruence, approximation space, (weakly) local approximation, locally reducible dependence space

Citation: Fundamenta Informaticae, vol. 58, no. 2, pp. 139-150, 2003

Authors: Terlikowski, Tomasz

Article Type: Research Article

Abstract: In this paper, we introduce the concept of risk in control. We pose ourselves and we try to answer the general question: what is risk function? The respective definitions using the necessary logical notions are formulated and analyzed with the aid of numerous examples. The reader will find all relevant notions in [14], [15], [16] and [17].

Keywords: set theory, control variants, risk function, functional description, elementariness

Citation: Fundamenta Informaticae, vol. 58, no. 2, pp. 151-165, 2003

Authors: Tsai, Chwei-Shyong | Chang, Chin-Chen

Article Type: Research Article

Abstract: A new segmentation technique that is suitable for object-based coding schemes is proposed in this paper. Focusing on DCT frequency coefficients, the proposed technique assigns each frequency coefficient a corresponding rate value according to the importance of edge information. On the other hand, it adopts frequency sensitivity and edge contrast information as well as the properties of the human visual system to weight each frequency coefficient. As a result, the segmentation technique proposed in this paper …can effectively reveal the necessary significant edges that make up the shape of objects so as to further facilitate obtaining meaningful objects. Show more

Keywords: MPEG, object-based coding, human visual system, DCT

Citation: Fundamenta Informaticae, vol. 58, no. 2, pp. 167-178, 2003

Authors: Tsai, Chwei-Shyong | Chang, Chin-Chen

Article Type: Research Article

Abstract: To reduce blocking artifacts and enhance visual quality, a simple and efficient DWT-based technique is proposed for post-processing of block-based encoded images. Basically, the technique proposed in this paper removes the blocking artifacts that appear in smooth blocks within the DWT frequency domain. From the experimental results, we see that the proposed technique can easily and effectively remove the blocking artifacts as well as enhance the visual quality of an image. In addition, compared with some …other current deblocking methods, the deblocked images created by using the proposed technique have higher PSNR. Show more

Keywords: Blocking artifact, DWT, JPEG

Citation: Fundamenta Informaticae, vol. 58, no. 2, pp. 179-188, 2003

Authors: Wu, Hsien-Chu | Chang, Chin-Chen

Article Type: Research Article

Abstract: This paper proposes a fractal-based watermarking scheme that efficiently protects the intellectual property rights of digital images. The main feature of fractal encoding is that it uses the self-similarity between the larger and smaller parts of an image to compress the image. When our scheme uses this self-similar relationship, it effects both the embedding and extraction of the watermark. As seen from the experimental results, the proposed scheme provides more robust capability than other compression-based …watermarking techniques. Show more

Keywords: Affine transformation, digital watermarking technique, fractal image compression, intellectual property rights, self-similarity

Citation: Fundamenta Informaticae, vol. 58, no. 2, pp. 189-202, 2003