[1]Sino-German Faculty,Qingdao University of Science and Technology,Qingdao266061,China;
[2]School of Information Science and Technology,Qingdao University of Science and Technology,Qingdao266061,China;
[3]College of Computer Science and Technology,Harbin Engineering University,Harbin150001,China;
[2]School of Information Science and Technology,Qingdao University of Science and Technology,Qingdao266061,China;
Character variable; Natural bases; Dimension expanding; Text classification;