ChengduInstituteofComputerApplications;
ChineseAcademyofSciences;
Chengdu610041;
P.R.China;
ChengduInstituteofComputerApplications;
ChineseAcademyofSciences;
Chengdu610041;
P.R.China//FakultaetfürMathematikundInformatik;
Universit[itMannheim;
D7;
27;
68131Mannheim;
Germany;