Submitted on: 13 October 2015.
Revised on: 01 November 2015.
Accepted on: 21 November 2015.
PROCEEDINGS OF THE EDINBURGH MATHEMATICAL SOCIETY
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Submitted on: 04 July 2008.
Revised on: 08 August 2008.
Accepted on: 20 August 2008.
PROCEEDINGS OF THE EDINBURGH MATHEMATICAL SOCIETY
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Submitted on: 22 May 2016.
Revised on: 30 May 2016.
Accepted on: 17 June 2016.
PROCEEDINGS OF THE EDINBURGH MATHEMATICAL SOCIETY
Submitted on: 06 January 2009.
Revised on: 18 February 2009.
Accepted on: 11 March 2009.
PROCEEDINGS OF THE EDINBURGH MATHEMATICAL SOCIETY
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