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Issue 1, Volume 7, January 2008
Print ISSN: 1109-2750
E-ISSN: 2224-2872

 
 

 

 

 

 

 

 


Title of the Paper:  Constraint Satisfaction Problem Using Modified Branch and Bound Algorithm

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Authors: Azlinah Mohamed, Marina Yusoff, Itaza Afiani Mohtar, Sofianita Mutalib, Shuzlina Abdul Rahman

Abstract: A constraint satisfaction problem (CSP) involves assigning possible values to a set of variables without defying any constraints. There are various techniques available to solve or give partial solution to CSP. This paper presents a modification of branch and bound algorithm, which is used to solve a constraint satisfaction problem in map colouring problem. There are two constraints involved which are only three colours are allowed to be used and adjacent regions in the map must not be of the same colour. The modified branch and bound algorithm uses back jumping when it encounters a dead-end in the search. Static variable ordering was also applied to aid the searching process. The modified branch and bound algorithm shows a better result in terms of the number of nodes instantiated and the reduced number of backtracking at dead ends. The result illustrated that the modified branch and bound algorithm with the use of variable ordering technique is better if compared to backjumping. Thus, it is concluded that the modified branch and bound algorithm would improve constraint satisfaction problem. 


Keywords:
Backjumping, Branch and Bound Algorithm, Constraint Satisfaction Problem, and Static Variable Ordering  

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Title of the Paper: An Application of Type-2 Fuzzy Notions in Website Structures Selection: Utilizing Extended TOPSIS Method

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Authors: Hamed Qahri Saremi, Gholam Ali Montazer

Abstract: Giving more effectiveness to e-commerce sites increases customer satisfaction as visitors can navigate the website easier and find their targets in less time and cost. With the development of web content, the structure of a website becomes more complex and critical to both web designers and users in a way that has made the prioritizing of various options of website structure a pivotal decision making problem incorporating large uncertainty in judgment. Finding a response to such a need, TOPSIS, a conventional MADM technique, had been a mere remedy for years, solving the problems with a more or less adequate accuracy. In an aspiring step toward an improvement in this method, Fuzzy TOPSIS method, a combination of ordinary TOPSIS method and Fuzzy theory, could heal some of shortcomings of uncertainties and ordinary TOPSIS in decision making. However there are still lots of occasions in which decision making is faced with lots of shadowiness making the Fuzzy TOPSIS method not sufficiently receptive. As a sensible response to this drawback, in this paper, we utilize a brand-new extension to TOPSIS and Fuzzy TOPSIS methods, based on type-2 fuzzy notions with ability to cope with type-2 fuzzy environment and data incorporating much more fuzziness in decision making. We apply this method to a vague case of the real world and discuss its results against the other previously-developed TOPSIS methods. 

Keywords: Decision Making; Website Structure; TOPSIS; Type-2 Fuzzy Sets; Interval Valued Fuzzy Sets; MADM; Fuzzy TOPSIS; IVF-TOPSIS  

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Title of the Paper: A Novel Robust Watermarking Technique Using IntDCT Based AC Prediction

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Authors: Kuo-Ming Hung

Abstract: Because of the blocking artifacts resulted from 8x8 Discrete Cosine Transform (DCT) , most watermarking technologies have been proposed using DCT whose image quality was not very good. In 1990, Gonzales et al. described a technique which predicts a few low frequency AC coefficients. The AC predictor uses the dequantized DC values of a 3x3 neighborhood of 8x8 blocks to predict the AC values in the center block. Wang proposed a data hiding scheme using the AC prediction technology in 2005. But it is unable to be suitable for the image of all types to predict AC coefficients accurately. We propose a new watermarking system by using the technologies of 4x4 integer DCT transform and adaptive AC estimation. We use 4x4 INTDCT transform to reduce blocking artifacts caused from 8x8 DCT transform and improve Imperceptibility and watermark capacity greatly. Moreover, we utilize AC prediction value as error-checking code to enhance robustness of watermark.  

Keywords: Watermark; DCT; IntDCT; AC prediction; H.264

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Title of the Paper: Implementation Feasibility of Convex Recursive Deletion Regions Using Multi-Layer Perceptrons

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Authors: Che-Chern Lin

Abstract: A constructive algorithm to implement convex recursive deletion regions via two-layer perceptrons has been presented in a recent study. In the algorithm, the absolute values of the weights become larger and larger when the number of nested layers of a convex recursive deletion region increases. In addition, the absolute values of the weights are determined according to the complexity of the structure of the convex recursive deletion region. More complicated convex recursive deletion regions result in larger values of weights. Besides, the constructive procedure is needed to get the parameters (weights and thresholds) for the neural networks. In this paper, we propose a simple three-layer network structure to implement the convex recursive deletion regions in which all weights of the second and third layers are all 1ís and the thresholds for the nodes in the second layer are pre-determined according to the structures of the convex recursive deletion regions. This paper also provides the activation function for the output node. In brief, all of parameters (weights and activation functions) in the proposed structure are pre-determined and no constructive algorithm is needed for solving the convex recursive deletion region problems. We prove the feasibility of the proposed structure and give an illustrative example to demonstrate how the proposed structure implements the convex recursive deletion regions. Finally, we provide the conceptual diagram of the hardware implementation of the proposed network structure.  

Keywords: Multi-layer perceptrons, nested decision region, convex recursive deletion region, hardware implementation.   

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Title of the Paper: Construction of Virtual Backbone on Growth-Bounded Graph with Variable Transmission Range

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Authors: Yanjing Sun, Xiangping Gu, Jiansheng Qian

Abstract: Virtual backbone has been used extensively in various aspects for wireless ad hoc or sensor networks recently. We propose an approximation solution to construct a virtual backbone based on a more generalized and realistic model of polynomial bounded growth. A localized distributed algorithm of MCDS_GBG for computing a Minimum Connected Dominating Sets as backbone in the growth-bounded graph is presented. This approach consists of three stages: firstly construct an MIS by network decomposition scheme; secondly compute a minimum dominating set in 2-separated collection with r transmission range and finally use Marking process and ruling k to reduce the virtual backbone with 3r transmission range. The computed Connected Dominating Set guarantees a constant stretch factor on the length of a shortest path and induces a subgraph of constant degree while the nodes only require direct neighborhood information. The efficiency of our approach is confirmed through both theoretical analysis and comparison study.  

Keywords: Virtual backbone; Growth-bounded graph; Connected dominating sets; Maximal independent sets; Wireless ad hoc sensor network; Network decomposition   

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