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Submitted on: 31 October 2001.
Revised on: 24 January 2002.
Accepted on: 18 March 2002.
___________________JOURNAL OF PURE AND APPLIED ALGEBRA
Submitted on: 26 August 2002.
Revised on: 17 December 2002.
Accepted on: 13 February 2003.
___________________JOURNAL OF PURE AND APPLIED ALGEBRA
Submitted on: 20 March 2007.
Revised on: 08 July 2007.
Accepted on: 29 August 2007.
___________________JOURNAL OF PURE AND APPLIED ALGEBRA
Submitted on: 15 March 2010.
Revised on: 14 May 2010.
Accepted on: 21 June 2010.
___________________JOURNAL OF PURE AND APPLIED ALGEBRA
Submitted on: 15 November 2018.
Revised on: 12 February 2019.
Accepted on: 17 March 2019.
___________________JOURNAL OF PURE AND APPLIED ALGEBRA