Cai, Hong
Chen, Geng
Chen, Robin Ming
Shen, Yannan
Funding for this research was provided by:
doctoral found of Qingdao University of Science and Technology (010022896)
Division of Mathematical Sciences (1715012)
Division of Mathematical Sciences (1613375)
Simons Foundation (354996)
Article History
Received: 18 November 2016
Accepted: 22 February 2018
First Online: 7 March 2018