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Submitted on: 07 February 1999.
Revised on: 19 March 1999.
Accepted on: 10 May 1999.
___________________INFORMATION PROCESSING LETTERS
Submitted on: 02 January 2017.
Revised on: 16 March 2017.
Accepted on: 27 April 2017.
___________________INFORMATION PROCESSING LETTERS
Submitted on: 26 May 2014.
Revised on: 23 August 2014.
Accepted on: 01 October 2014.
___________________INFORMATION PROCESSING LETTERS
Submitted on: 28 February 2014.
Revised on: 26 June 2014.
Accepted on: 03 August 2014.
___________________INFORMATION PROCESSING LETTERS
Submitted on: 14 October 2014.
Revised on: 01 December 2014.
Accepted on: 03 January 2015.
___________________INFORMATION PROCESSING LETTERS