CRITICAL POINT;
SADDLE POINT THEOREM;
PALAIS-SMALE CONDITION;
D O I:
10.2307/2159584
中图分类号:
O29 [应用数学];
学科分类号:
070104 ;
摘要:
We consider the system of second order differential equations u" + del G(u) = e(t) = e(t + T), where the potential G: R(n) --> R is not necessarily convex. Using critical point theory, we give conditions under which the system has infinitely many subharmonic solutions.