Submitted on: 16 May 2002.
Revised on: 18 June 2002.
Accepted on: 14 July 2002.
Theory of Probability and Mathematical Statistics
http://reply.papertrans.cn/3/295/29433/29433-32.png
http://reply.papertrans.cn/3/295/29433/29433-33.png
Submitted on: 30 April 2008.
Revised on: 09 May 2008.
Accepted on: 19 May 2008.
Theory of Probability and Mathematical Statistics
http://reply.papertrans.cn/3/295/29433/29433-35.png
http://reply.papertrans.cn/3/295/29433/29433-36.png