Submitted on: 26 July 2015.
Revised on: 18 October 2015.
Accepted on: 08 December 2015.
___________________Communications in Combinatorics and Optimization
http://reply.papertrans.cn/1/61/6004/6004-32.png
Submitted on: 28 March 1998.
Revised on: 14 May 1998.
Accepted on: 30 May 1998.
___________________Communications in Combinatorics and Optimization
Submitted on: 12 December 2001.
Revised on: 04 February 2002.
Accepted on: 28 March 2002.
___________________Communications in Combinatorics and Optimization
Submitted on: 10 October 2008.
Revised on: 01 November 2008.
Accepted on: 12 November 2008.
___________________Communications in Combinatorics and Optimization
Submitted on: 04 January 2017.
Revised on: 10 March 2017.
Accepted on: 28 April 2017.
___________________Communications in Combinatorics and Optimization