Department;
of;
Mathematics,;
Xinyang;
Teachers;
College,;
Xinyang;
464000,;
Henan,;
China;
Beijing;
Institute;
of;
Information;
and;
Control,;
Beijing;
100037,;
China;
Academy;
of;
Mathematics;
and;
System;
Science,;
C.A.S.;
Beijing;
100080,;
China;