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Submitted on: 06 February 2004.
Revised on: 14 March 2004.
Accepted on: 16 April 2004.
___________________IMA Journal of Management Mathematics
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Submitted on: 16 December 2002.
Revised on: 11 March 2003.
Accepted on: 18 April 2003.
___________________IMA Journal of Management Mathematics
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Submitted on: 03 February 2010.
Revised on: 24 May 2010.
Accepted on: 14 July 2010.
___________________IMA Journal of Management Mathematics
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