Bashar Al-Rawi

Microsoft, Washington, West Virginia, United States

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Publications (3)0 Total impact

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    ABSTRACT: The Employee Timetabling Problem (ETP) is concerned with assigning a number of employees into a given set of shifts over a fixed period of time while meeting the employee's preferences and organizational work regulations. The problem also attempts to optimize the performance criteria and distribute the shifts equally among the employees. The problem is known to be a complex optimization problem. It has received intensive research during the past few years given its common use in industries and organizations. Several formulations and algorithms based on incomplete search approaches have been proposed to solve employee timetabling problems. In this paper, we propose a complete search approach using Boolean satisfiability (SAT) and integer linear programming (ILP) to solve these problems. The 0-1 ILP model of interest is developed and solved using advanced SAT and ILP solvers. A tool has also been developed to automate the process of producing and solving the ILP model. Experimental results indicate that the proposed approach can effectively handle employee timetabling problems.
    Full-text · Article · Apr 2013 · Journal of Computers
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    Fadi A. Aloul · Bashar Al-Rawi · Mokhtar Aboelaze
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    ABSTRACT: Optical networks consist of switches that are connected using fiber optics links. Each link consists of a set of wavelengths and each wavelength can be used by one or more users to transmit information between two switches. In order to establish a connection between the source and destination nodes, a set of switches and links must be efficiently selected. This is known as the routing problem. A wavelength is then assigned in each selected link to establish the connection. This is known as the wavelength assignment problem. The problem of routing and wavelength assignment (RWA) in optical networks has been shown to be NP-complete. In this paper, we propose a new approach to solving the RWA problem using advanced Boolean satisfiability (SAT) techniques. SAT has been heavily researched in the last few years. Significant advances have been proposed and have lead to the development of powerful SAT solvers that can handle very large problems. SAT solvers use intelligent search algorithms that can traverse the search space and efficiently prune parts that contain no solutions. These solvers have recently been used to solve many challenging problems in Engineering and Computer Science. In this paper, we show how to formulate the RWA problem as a SAT instance and evaluate several advanced SAT techniques in solving the problem. Our approach is verified on various network topologies. The results are promising and indicate that using the proposed approach can improve on previous techniques.
    Full-text · Conference Paper · Feb 2008
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    Fadi Aloul · Bashar Al-Rawi · Anas Al-Farra · Basel Al-Roh
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    ABSTRACT: The employee timetabling problem (ETP) is concerned with assigning a number of employees into a given set of shifts over a fixed period of time, e.g. a week, while meeting the employee's preferences and organizational work regulations. The problem also attempts to optimize the performance criteria and distribute the shifts equally among the employees. The problem is considered a classical NP-complete optimization problem. It has received intensive research during the past few years given its use in industries and organizations. Several formulations and algorithms based on local search have been proposed to solve ETPs (Dowsland, 1998; Kragelund, 1997; Meisels et al., 1997; and Meisels and Schaerf, 2003). In this paper, we propose a complete approach using integer linear programming (ILP) to solve these problems. The ILP model of interest is developed and solved using the generic ILP solver CPLEX and the Boolean satisfiability ILP solver PBS. Experimental results indicate that the proposed model is tractable for reasonable-sized ETP problems
    Full-text · Conference Paper · Dec 2006