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Jang, Injoo; Yoo, Hyeong Seon
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This paper proposes an efficient inversion algorithm for Galois field GF(2^{n}) by using a modified multibit shifting method. It is well known that the efficiency of arithmetic algorithms depends on the basis and many foregoing papers use either polynomial or optimal normal basis. An inversion algorithm, which modifies a multibit shifting based on the Montgomery algorithm, is studied. Trinomials and AOPs (allone polynomials) are tested to calculate the inverse. It is shown that the suggested inversion algorithm reduces the computation time 1 ~ 26% of the forgoing multibit shifting algorithm. The modified algorithm can be applied in various applications and is easy to implement.
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Mysore, Venkatesh; Pnueli, Amir
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2 Citations
Reachability becomes undecidable in hybrid automata (HA) that can simulate a Turing (TM) or Minsky (MM) machine. Asarin and Schneider have shown that, between the decidable 2dim Piecewise Constant Derivative (PCD) class and the undecidable 3dim PCD class, there lies the “open” class 2dim Hierarchical PCD (HPCD). This class was shown to be equivalent to the class of 1dim Piecewise Affine Maps (PAM). In this paper, we first explore 2dim HPCD’s proximity to decidability, by showing that they are equivalent to 2dim PCDs with translational resets, and to HPCDs without resets. A hierarchy of intermediates also equivalent to the HPCD class is presented, revealing semblance to timed and initialized rectangular automata. We then explore the proximity to the undecidability frontier. We show that 2dim HPCDs with zeno executions or integerchecks can simulate the 2counter MM. We conclude by retreating HPCDs as PAMs, to derive a simple overapproximating algorithm for reachability. This also defines a decidable subclass 1dim Onto PAM (oPAM). The novel nontrivial transformation of 2dim HPCDs into “almost decidable” systems, is likely to pave the way for approximate reachability algorithms, and the characterization of decidable subclasses. It is hoped that these ideas eventually coalesce into a complete understanding of the reachability problem for the class 2dim HPCD (1dim PAM).
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Gao, Wei; Wong, KamFai; Lam, Wai
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Abstract
A proper noun dictionary is never complete rendering name translation from English to Chinese ineffective. One way to solve this problem is not to rely on a dictionary alone but to adopt automatic translation according to pronunciation similarities, i.e. to map phonemes comprising an English name to the phonetic representations of the corresponding Chinese name. This process is called transliteration. We present a statistical transliteration method. An efficient algorithm for aligning phoneme chunks is described. Unlike rulebased approaches, our method is datadriven. Compared to sourcechannel based statistical approaches, we adopt a direct transliteration model, i.e. the direction of probabilistic estimation conforms to the transliteration direction. We demonstrate comparable performance to sourcechannel based system.
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Zhovtobryukh, Dmytro; Hara, Veikko
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Future services must become intelligent to meet the high demands of pervasive computing environments. But until pervasive systems with their ambient intelligence supersede conventional mobile computing environments, it is quite a challenge to incorporate contextawareness and adaptability in services currently available. Such step would bring outstanding flexibility and ubiquity to contemporary mobile computing systems and semantically rich web environments. This paper presents a distinct vision of portable service provisioning which elaborates the concept of a portable service by proposing a dynamic reconfigurable service application design based on contextaware infrastructure support.
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Ceravolo, Paolo; Rocacher, Daniel
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The KIWI project developed a platform called OntoExtractor enabling semiautomatic extraction of ontologies. This platform is composed of different modules. A first module extract typical instances from a data flow. A second module propose some topological relations among the detected classes. A third module assist the knowledge engineer in transforming classes and relations tentatively proposed by the system in a standard knowledge representation format. This paper address the specific problem of detecting isa and partof relations among typical instances of a document base.
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Tsow, Alex; Johnson, Steven D.
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Design derivation, a correctbyconstruction system design method, specifies behavior with abstract datatypes. Refining these abstract datatypes is necessary for architectural decomposition. A new transformation primitive enables data refinement by generalizing term level injective homomorphisms to system equivalence.
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Jedrzejowicz, J.; Jedrzejowicz, P.
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The paper proposes an implementation of the population learning algorithm designed to solve instances of the quadratic assignment problem. A short overview of the population learning algorithm and a more detailed presentation of the proposed implementation is followed by the results of computational experiments carried. Particular attention is given to investigating performance characteristics and convergence of the PLA. Experiments have focused on identification of the probability distribution of solution time to a suboptimal target value.
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By
Hu, Guangming; Kuang, Xiaohui; Gong, Zhenghu
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2 Citations
Many emerging mobile wireless applications depend upon secure group communication, in which secure and efficient group rekeying algorithm is very important. In this paper, a novel rekeying algorithm is proposed, which is based on the Distributed Group Key Management Framework and secure clustering. This algorithm involves two phases: (a) Virtual Backbone Management phase: a dynamic virtual backbone is formed below the routing layer such that each node in the network is either a part of the backbone or one hop away from at least one of the backbone nodes. (b) Group Rekeying phase: backbone nodes form group rekeying forest, in which each group rekeying tree can generate a new and same groupkey. Because this algorithm generates group key with local secrete information, it is very fit for mobile ad hoc networks. Simulation shows that the algorithm performs better than many existing group key management protocols in terms of the success ratio and average delay of group rekeying.
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