Scientific Journals and Yearbooks Published at SAS

Article List

Computing and Informatics


Volume 24, 2005, No. 5

Content:


  Separating Concerns in Programming: Data, Control and Actions
J. KOLLAR, J. PORUBaN, P. VACLAVIK

Programming languages, process functional programming, AspectJ, aspect-oriented programming, PFL, computational reflection, programming environments

A multi-paradigm language provides an opportunity to a user for exploiting more programming methodologies. It simplifies the language syntax, and extends the application areas by the extended semantics. That is why multi-paradigm languages can align a problem in wider application areas and more flexibly than that based on a single paradigm. In this paper, we present the idea of separating three essential concerns of programming currently being implemented in PFL -- a process functional language. We separate data, control, and actions by the definition of a purely control structure. Then, by the structured application of a structure of actions to a purely control structure, we will express the computation of activated actions in a structured way, considering explicitly defined synchronization in computation.

Computing and Informatics. Volume 24, 2005, No. 5: 441-462.

 
  Decision Fusion and Contextual Information for Arabic Words Recognition
N. FARAH, L. SOUICI, M. SELLAMI

Arabic word recognition, holistic approach, multiclassifiers, decision fusion, contextual information

The study of multiple classifier systems has become recently an area of intensive research in pattern recognition. Also in handwriting recognition, systems combining several classifiers have been investigated. An approach for recognizing the legal amount for handwritten Arabic bank check is described in this article. The solution uses multiple information sources to recognize words. The recognition step is preformed with a parallel combination of three kinds of classifiers using holistic word structural features. The classification stage results are first normalized, and the sum combination is performed as a decision fusion scheme, after which a syntactic analyzer makes final decision on the candidate words. Using this approach, the obtained results are very interesting and promising.

Computing and Informatics. Volume 24, 2005, No. 5: 463-479.

 
  Efficient Vertical Handoffs in Wireless Overlay Networks
H. BADIS, Kh. AL AGHA

Overlay networks, micro-mobility, macro-mobility, mobile IP, vertical handoffs

Mobile IP is used to keep track of location information and make the data available to the mobile device anytime, anywhere. It is designed to address the macro-mobility management, it does not address micro-level mobility issues such as handoff latency and packet loss. In this paper, we propose a mobility management scheme to handle the movements of mobile nodes among different wireless network technologies. Our scheme combines: (a) A hierarchical mobility management architecture to hide mobility of mobile nodes within the foreign domain from the home agent; (b) A handoff protocol to reduce packet loss during the transition from one cell to another; (c) The use of our proposed virtual cells in order to reduce the upward vertical handoff latency and disruption as much as possible. Our design is based on the Internet Protocol (IP) and is compatible with the Mobile IP standard (MIP). We also present simulation results showing that our handoff scheme is very fast to meet the requirements of an interactive communication session such as Internet telephony and avoiding packet loss.

Computing and Informatics. Volume 24, 2005, No. 5: 481-494.

 
  An Image Retrieval System Based on the Color Complexity of Images
Yung-Kuan CHAN, Yi-Tung LIU, Rung-Ching CHEN

Image retrieval, color-based image retrrieval, color histogram, fuzzy color histogram

The fuzzy color histogram (FCH) spreads each pixel's total membership value to all histogram bins based on their color similarity. The FCH is insensitive to quantization errors. However, the FCH can state only the global properties of an image rather than the local properties. For example, it cannot depict the color complexity of an image. To characterize the color complexity of an image, this paper presents two image features -- the color variances among adjacent segments (CVAAS) and the color variances of the pixels within an identical segment (CVPWIS). Both features can explain not only the color complexity but also the principal pixel colors of an image. Experimental results show that the CVAAS and CVPWIS based image retrieval systems can provide a high accuracy rate for finding out the database images that satisfy the users' requirement. Moreover, both systems can also resist the scale variances of images as well as the shift and rotation variances of segments in images.

Computing and Informatics. Volume 24, 2005, No. 5: 495-511.

 
  Behavioural Equivalences on Finite-State Systems are PTIME-hard
Z. SAWA, P. JANCAR

Verification, finite transition systems, bisimulation equivalence, trace equivalence, computational complexity, PTIME-hardness

The paper shows a LOGSPACE-reduction from the Boolean circuit value problem which demonstrates that any relation subsuming bisimilarity and being subsumed by trace preorder (ie, language inclusion) is PTIME-hard, even for finite acyclic labelled transition systems. This reproves and substantially extends the result of Balcazar, Gabarro and Santha (1992) for bisimilarity.

Computing and Informatics. Volume 24, 2005, No. 5: 513-528.

 
  A (t, n) Threshold Secret Sharing System with Efficient Identification of Cheaters
Iuon-Chang LIN, Chin-Chen CHANG

Cheater identification, information security, secret sharing system

In this paper, we propose a new (t, n) threshold scheme. The scheme allows a user to divide portions of a secret among the designated group. Any t or more participants from a designated group of n members can cooperate to reconstruct the secret while (t-1) or less participants can not. Furthermore, the scheme provides an efficient mechanism to detect and identify cheaters. From the security analysis, we conclude that any participant does not have the ability to deceive other participants to obtain their portion of the secret. Therefore, this scheme is very practical for a broad spectrum of applications.

Computing and Informatics. Volume 24, 2005, No. 5: 529-541.