Submitted on: 30 October 2019.
Revised on: 24 December 2019.
Accepted on: 11 January 2020.
___________________Acta Universitatis Sapientiae Informatica
Submitted on: 31 January 1998.
Revised on: 05 May 1998.
Accepted on: 17 June 1998.
___________________Acta Universitatis Sapientiae Informatica
Submitted on: 05 July 2017.
Revised on: 22 September 2017.
Accepted on: 03 October 2017.
___________________Acta Universitatis Sapientiae Informatica
Submitted on: 25 July 2015.
Revised on: 20 September 2015.
Accepted on: 05 November 2015.
___________________Acta Universitatis Sapientiae Informatica
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Submitted on: 13 May 2009.
Revised on: 06 June 2009.
Accepted on: 04 July 2009.
___________________Acta Universitatis Sapientiae Informatica