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Submitted on: 26 August 2013.
Revised on: 08 October 2013.
Accepted on: 02 December 2013.
___________________Journal of Homotopy and Related Structures
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Submitted on: 10 September 2006.
Revised on: 07 January 2007.
Accepted on: 23 January 2007.
___________________Journal of Homotopy and Related Structures
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Submitted on: 11 February 2001.
Revised on: 10 March 2001.
Accepted on: 29 April 2001.
___________________Journal of Homotopy and Related Structures