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Rules for Transforming Order Dependent Transaction into Order Independent Transaction* Print E-mail

Rules for Transforming Order Dependent Transaction into Order Independent Transaction*

Hamidah Ibrahim

Department of Computer Science, Universiti Putra Malaysia, Malaysia

 

Abstract: A transaction is a collection of operations that performs a single logical function in a database application. Each transaction is a unit of both atomicity and consistency. Thus, transactions are required not to violate any database consistency constraints. In most cases, the update operations in a transaction are executed sequentially. The effect of a single operation in a transaction potentially may be changed by another operation in the same transaction. This implies that the sequential execution sometimes does some redundant work. A transaction with a set of update operations is order dependent if and only if the execution of the transaction following the serialibility order as in the transaction produce an output which will be different from the output produced by interchanging the operations in the transaction. Otherwise, the transaction is order independent [8]. In this paper, we present rules that can be applied to generate order independent transaction given an order dependent transaction. An order independent transaction has an important advantage of its update statements being executed in parallel without considering their relative execution orders. With an order independent transaction, we can consider its single updates in an arbitrary order. Furthermore, executing transaction in parallel can reduce the execution time.

Keywords: Transaction, parallel processing, transaction decomposition, subtransaction, update operations.

Received March 2, 2004; accepted June 29, 2004

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Integrating GIS and MCDM Using COM Technology Print E-mail

Integrating GIS and MCDM Using COM Technology

Khalid Eldrandaly1, Neil Eldin2, Daniel Sui1, Mohamed Shouman3, and Gamal Nawara4

1Geography Department, Texas A&M University, USA

2Construction Science Department, Texas A&M University, USA

3College of Computers and Informatics, Zagazig University, Egypt

4Industrial and Systems Engineering Department, Zagazig University, Egypt

Abstract: Problems involving the processing of spatial data such as industrial site selection and land use allocation are multi-facetted challenges. Not only they often involve numerous technical requirements, but may also contain economical, social, environmental and political dimensions that may have conflicting values. Solutions for these problems involve highly complex spatial data analysis processes and frequently require advanced means to address physical suitability conditions, while considering the multiple socio-economic variables. Geographic Information Systems (GIS) and Multi-Criteria Decision-Making techniques (MCDM) are two common tools employed to solve these problems. However, each suffers from serious shortcomings. GIS, which deals mainly with physical suitability analysis, has very limited capability of incorporating the decision maker’s preferences into the problem solving process. MCDM, which deals mainly with analyzing decision problems and evaluating the alternatives based on a decision maker’s values and preferences, lacks the capability of handling spatial data (e. g., buffering and overlay) that are crucial to spatial analysis. The need for combining the strengths of these two techniques has prompted researchers to seek integration of GIS and MCDM. Current integration strategies (loose coupling and tight coupling) have their own limitations. Such limitations were successfully eliminated by using Component Object Model (COM) technology to integrate GIS and MCDM. An illustrative example was included to validate the capabilities of the presented integration strategy.

Keywords: GIS, MCDM, AHP, integration strategies, software interoperability.

Received March 1, 2004; accepted May 29, 2004

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Solving the Maximum Satisfiability Problem Using an Evolutionary Local Search Print E-mail

Solving the Maximum Satisfiability Problem Using an Evolutionary Local Search Algorithm

Mohamed El Bachir Menai1 and Mohamed Batouche2

1Artificial Intelligence Laboratory, University of Paris 8, France

2 Computer Science Department, University Mentouri of Constantine, Algeria

 

Abstract: The MAXimum propositional SATisfiability problem (MAXSAT) is a well known NP-hard optimization problem with many theoretical and practical applications in artificial intelligence and mathematical logic. Heuristic local search algorithms are widely recognized as the most effective approaches used to solve them. However, their performance depends both on their complexity and their tuning parameters which are controlled experimentally and remain a difficult task. Extremal Optimization (EO) is one of the simplest heuristic methods with only one free parameter, which has proved competitive with the more elaborate general-purpose method on graph partitioning and coloring. It is inspired by the dynamics of physical systems with emergent complexity and their ability to self-organize to reach an optimal adaptation state. In this paper, we propose an extremal optimization procedure for MAXSAT and consider its effectiveness by computational experiments on a benchmark of random instances. Comparative tests showed that this procedure improves significantly previous results obtained on the same benchmark with other modern local search methods like WSAT, simulated annealing and Tabu Search (TS).

Keywords: Constraint satisfaction, MAXSAT, heuristic local search, extremal optimization.

Received February 29, 2004; accepted June 30, 2004

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A Connectionist Expert Approach for Print E-mail

A Connectionist Expert Approach for Speech Recognition

Halima Bahi and Mokhtar Sellami

Department of Computer Science, University of Annaba, Algeria

 

Abstract: Artificial Neural Networks (ANNs) are widely and successfully used in speech recognition, but still many limitations are inherited to their topologies and learning style. In an attempt to overcome these limitations, we combine in a speech recognition hybrid system the pattern processing of ANNs and the logical inferencing of symbolic approaches. In particular, we are interested in the Connectionist Expert System (CES) introduced by Gallant [10], it consists of an expert system implemented throughout a Multi Layer Perceptron (MLP). In such network, each neuron has a symbolic significance. This will overcome one of the difficulties encountered when we built an MLP, which is how to find the appropriate network configuration and will provide it with explanation capabilities. In this paper, we present a CES dedicated to Arabic speech recognition. So, we implemented a neural network where the input neurons represent the acoustical level, they are defined using the vector quantization techniques. The hidden layer represents the phonetic level and according to the Arabic particularities, the used phonetic unit is the syllable. Finally, the output neurons stand for the lexical level, since they are the vocabulary words.

Keywords: Artificial intelligence, speech recognition, hybrid system, neuro-symbolic integration, expert system, neural networks.

Received February 23, 2004; accepted July 8, 2004

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Data Integration in a PLM Perspective for Mechanical Products Print E-mail

Data Integration in a PLM Perspective for Mechanical Products

Sihem Mostefai1, Abdelaziz Bouras2, and Mohamed Batouche1

1Department of Computing Science, University Mentouri of Constantine, Algeria

2CERRAL, IUT Lumière, University of Lyon II, France

Abstract: One of today’s hottest topics in information technology is integration. In this paper, we deal with the problem of data integration in a Product Lifecycle Management (PLM) vision. That is, how to integrate product data throughout the entire product lifecycle, ranging from conception, through design, to manufacture, operation and destruction. This paper presents three approaches studied in the context of mechanical products to show how the problem of integration is dealt with. The study is mainly based on some examples of activities (or phases) taken from the product development lifecycle. Including the entire set of activities is out of the scope of this paper. Nevertheless, the three proposed approaches; meta-data, features, and ontologies show enough flexibility and potential to be generalized quite easily to other phases.

Keywords: Multiple view feature modelling, collaborative design, data exchange, PLM, data integration.

Received February 21, 2004; accepted July 6, 2004

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