http://reply.papertrans.cn/1/60/5931/5931-31.png
http://reply.papertrans.cn/1/60/5931/5931-32.png
Submitted on: 19 December 2008.
Revised on: 12 January 2009.
Accepted on: 08 March 2009.
___________________COMBINATORICA---SPRINGER HEIDELBERG
Submitted on: 19 January 2016.
Revised on: 09 May 2016.
Accepted on: 08 June 2016.
___________________COMBINATORICA---SPRINGER HEIDELBERG
http://reply.papertrans.cn/1/60/5931/5931-35.png
Submitted on: 17 June 2021.
Revised on: 27 August 2021.
Accepted on: 25 September 2021.
___________________COMBINATORICA---SPRINGER HEIDELBERG