Submitted on: 13 June 2001.
Revised on: 07 July 2001.
Accepted on: 01 August 2001.
___________________Journal for Geometry and Graphics
Submitted on: 26 January 2008.
Revised on: 02 March 2008.
Accepted on: 02 April 2008.
___________________Journal for Geometry and Graphics
Submitted on: 26 April 2004.
Revised on: 06 August 2004.
Accepted on: 17 August 2004.
___________________Journal for Geometry and Graphics
Submitted on: 07 December 2016.
Revised on: 23 January 2017.
Accepted on: 13 March 2017.
___________________Journal for Geometry and Graphics
http://reply.papertrans.cn/2/150/14970/14970-25.png
Submitted on: 18 July 2011.
Revised on: 04 September 2011.
Accepted on: 25 September 2011.
___________________Journal for Geometry and Graphics
Submitted on: 16 April 2006.
Revised on: 23 July 2006.
Accepted on: 12 August 2006.
___________________Journal for Geometry and Graphics
http://reply.papertrans.cn/2/150/14970/14970-28.png
Submitted on: 11 August 2001.
Revised on: 20 September 2001.
Accepted on: 18 October 2001.
___________________Journal for Geometry and Graphics
Submitted on: 28 March 2008.
Revised on: 01 July 2008.
Accepted on: 21 July 2008.
___________________Journal for Geometry and Graphics