[1] Yunnan Univ, Dept Stat, Kunming 650091, Yunnan, Peoples R China
[2] Univ Hong Kong, Dept Stat & Actuarial Sci, Pokfulam Rd, Hong Kong, Hong Kong, Peoples R China
[3] South Univ Sci & Technol China, Dept Math, Shenzhen 518055, Guangdong, Peoples R China