Fundamenta Informaticae - Volume 65, issue 4

Authors: Chan, Chi-Shiang | Chang, Chin-Chen

Article Type: Research Article

Abstract: Simple least-significant-bit (LSB) substitution is the most straightforward way to embed the secret image in the host image. Based on the simple LSB substitution, the method using substitution table is proposed to improve the quality of the stego-image. In this paper, we shall bring up a new method that uses the un-embedded host pixel bits to partition the host pixel into different planes. This way, we can derive the optimal substitution table for each plane. By …combining the optimal substitution tables, we can obtain the final result that we call the multi-bit-reference substitution table. After transforming the secret data according multi-bit-reference substitution table, we can embed the transformed secret data in the host image so that the host image will be degraded possibly less. The experimental results show that our method leads to good results. Show more

Keywords: Image hiding, least-significant-bit substitution, dynamic programming

Citation: Fundamenta Informaticae, vol. 65, no. 4, pp. 291-305, 2005

Authors: Georgescu, Irina

Article Type: Research Article

Abstract: In a previous paper connections between the congruence axioms WFCA, SFCA and the revealed preference axioms WAFRP, SAFRP for fuzzy choice functions whose domain contains the characteristic functions of pairs and of triples of alternatives have been studied. The first objective of this paper is to establish such connections for the case of arbitrary fuzzy choice functions. We introduce the new revealed preference axioms WAFRP^o , SAFRP^o , HAFRP and we prove …two main theorems: 1. The axioms WFCA and WAFRP^o are equivalent; 2. The axioms SFCA and HAFRP are equivalent. Our second objective is to define G-rational, M-rational, G-normal and M-normal fuzzy choice functions and to investigate some of their properties. The notions and the results are formulated in terms of the residuum of the Gödel t-norm and the proofs use the residuated lattice structure of the interval [0,1]. Show more

Keywords: Revealed preference, fuzzy choice function, rationality, normality

Citation: Fundamenta Informaticae, vol. 65, no. 4, pp. 307-328, 2005

Authors: Li, Sanjiang | Ying, Mingsheng | Li, Yongming

Article Type: Research Article

Abstract: Region Connection Calculus (RCC) is the most widely studied formalism of Qualitative Spatial Reasoning. It has been known for some time that each connected regular topological space provides an RCC model. These 'standard' models are inevitable uncountable and regions there cannot be represented finitely. This paper, however, draws researchers' attention to RCC models that can be constructed from finite models hierarchically. Compared with those 'standard' models, these countable models have the nice property that …regions where can be constructed in finite steps from basic ones. We first investigate properties of three countable models introduced by Düuntsch, Stell, Li and Ying, resp. In particular, we show that (i) the contact relation algebra of our minimal model is not atomic complete; and (ii) these three models are non-isomorphic. Second, for each n>0, we construct a countable RCC model that is a sub-model of the standard model over the Euclidean unit n-cube; and show that all these countable models are non-isomorphic. Third, we show that every finite model can be isomorphically embedded in any RCC model. This leads to a simple proof for the result that each consistent spatial network has a realization in any RCC model. Show more

Keywords: Region Connection Calculus, Qualitative Spatial Reasoning, (Generalized) Boolean connection algebra, Countable RCC models, Hierarchical spatial reasoning

Citation: Fundamenta Informaticae, vol. 65, no. 4, pp. 329-351, 2005

Authors: Lu, Tzu-Chuen | Chang, Chin-Chen

Article Type: Research Article

Abstract: The vector quantization (VQ) compression scheme has been well accepted as an efficient image compression technique. However, the compression bit rate of the VQ scheme is limited. In order to improve its efficiency, in this paper, we shall propose a new lossless data compression scheme to further condense the VQ index table. The proposed scheme exploits the inter-block correlations in the index table to re-encode the indices. Unlike the well known existing re-encoding schemes such as …SOC and STC, the proposed scheme uses a smaller number of compression codes to encode every index that coincides with another on the predefined path. Compared with VQ, SOC and STC, the proposed scheme performs better in terms of compression bit rate. Show more

Keywords: vector quantization, index table, SOC, STC, data compression

Citation: Fundamenta Informaticae, vol. 65, no. 4, pp. 353-371, 2005

Authors: Richard, Adrien | Comet, Jean-Paul | Bernot, Gilles

Article Type: Research Article

Abstract: In the field of biological regulation, models extracted from experimental works are usually complex networks comprising intertwined feedback circuits. The overall behavior is difficult to grasp and the development of formal methods is needed in order to model and simulate biological regulatory networks. To model the behavior of such systems, R. Thomas and coworkers developed a qualitative approach in which the dynamics is described by a state transition system. Even if all steady states of the …system can be detected in this formalism, some of them, the singular ones, are not formally included in the transition system. Consequently, temporal properties in which singular states have to be described, cannot be checked against the transition system. However, steady singular states play an essential role in the dynamics since they can induce homeostasis or multistationnarity and sometimes are associated to biological phenotypes. These observations motivated our interest for developing an extension of Thomas formalism in which all singular states are represented, allowing us to check temporal properties concerning singular states. We easily demonstrate in our formalism the previously demonstrated theorems giving the conditions for the steadiness of singular states. We also prove that our formalism is coherent with the Thomas one since all paths of the Thomas transition system are preserved in our one, which in addition includes singular states. Show more

Keywords: biological networks, feedback circuits, singular states, steady states

Citation: Fundamenta Informaticae, vol. 65, no. 4, pp. 373-392, 2005