http://reply.papertrans.cn/2/103/10260/10260-31.png
http://reply.papertrans.cn/2/103/10260/10260-32.png
Submitted on: 15 December 2015.
Revised on: 09 January 2016.
Accepted on: 31 January 2016.
___________________Frontiers of Mathematics in China
Submitted on: 07 September 2016.
Revised on: 28 December 2016.
Accepted on: 17 January 2017.
___________________Frontiers of Mathematics in China
Submitted on: 03 March 2010.
Revised on: 14 April 2010.
Accepted on: 08 May 2010.
___________________Frontiers of Mathematics in China
http://reply.papertrans.cn/2/103/10260/10260-36.png