基金We acknowledge the financial support fromNational Social Science Foundation of China(SSFC Grant 07AJL002)National Natural Science Foundation of China(NSFC Grant 70825003).
基金This research is supported by a project of Financial Mathematics,Financial Engineering and Financial Management,which is one of"Ninth Five-Hear Plan"Major Projects of National Natural Science Foundation of China(Grant 79790130)Basic Research Foundation,School of Economics and Management,Tsinghua University.