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Submitted on: 10 May 2006.
Revised on: 05 July 2006.
Accepted on: 01 August 2006.
___________________International Journal of Mathematics and Computer Science
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Submitted on: 19 August 2023.
Revised on: 01 October 2023.
Accepted on: 28 October 2023.
___________________International Journal of Mathematics and Computer Science
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Submitted on: 18 September 2019.
Revised on: 23 November 2019.
Accepted on: 04 January 2020.
___________________International Journal of Mathematics and Computer Science