Submitted on: 07 September 2006.
Revised on: 23 December 2006.
Accepted on: 16 February 2007.
___________________ARS Mathematica Contemporanea---UP FAMNIT
http://reply.papertrans.cn/1/27/2642/2642-12.png
http://reply.papertrans.cn/1/27/2642/2642-13.png
http://reply.papertrans.cn/1/27/2642/2642-14.png
http://reply.papertrans.cn/1/27/2642/2642-15.png
http://reply.papertrans.cn/1/27/2642/2642-16.png
http://reply.papertrans.cn/1/27/2642/2642-17.png
Submitted on: 16 February 1998.
Revised on: 25 March 1998.
Accepted on: 20 May 1998.
___________________ARS Mathematica Contemporanea---UP FAMNIT
Submitted on: 17 June 2008.
Revised on: 12 August 2008.
Accepted on: 28 September 2008.
___________________ARS Mathematica Contemporanea---UP FAMNIT
Submitted on: 15 May 2005.
Revised on: 29 June 2005.
Accepted on: 17 July 2005.
___________________ARS Mathematica Contemporanea---UP FAMNIT