supported by grants from The National Natural Science Foundation of China(60873146,60973092,60903097,61172183);Hi-Tech Research and Development Program of China(2009AA02Z307);Project of Science and Technology Innovation Platform of Computing and Software Science(985 Engineering);The Key Laboratory for Symbol Computation and Knowledge Engineering of the National Education Ministry of China;Graduate Innovation Fund of Jilin University(20111062);Natural Science Foundation of Jilin Province(20101503)~~