我们研究二阶Hamiltonian系统-ü=▽F1(t,u)+ε▽F2(t,u)a。e。t∈[0,T]的多重周期解,其中ε是一个参数,T>0。F1(F2)∶R×RN→R关于t是T周期的,▽F1(t,x)关于x是奇的;并且Fi(t,x)(i=1,2)对所有x∈RN关于t是可测的,对几乎所有t∈[0,T]关于x是连续可微的,而且存在a∈C(R+,R+),b∈L+(0,T;R+)使得|Fi(t,x)|≤a(|x|)b(t),|▽Fi(t,x)|≤a(|x|)b(t)对所有x∈RN及几乎所有t∈[0,T]成立。我们对F1施加适当的条件,能够证明对任意的j∈N存在εj>0使得|ε|≤εj,则上述问题至少有j个不同的周期解。
We study the multiplicity of periodic solutions for second order hamiltonian systems-ü=▽F1(t,u)+ε▽F2(t,u)a.e.t∈[0,T],whereεis a parameter and T〉0,F1(F2)∶R×RN→Ris Tperiodic int,▽F1(t,x)is odd with respect to x,Fi(t,x)(i=1,2)is measurable intfor all x∈RNand continuously differentiable in xfor a.e.t∈ [0,T],and there exist a∈C(R+,R+),b∈L+(0,T;R+)such that|Fi(t,x)|≤a(|x|)b(t),|▽Fi(t,x)|≤a(|x|)b(t)for all x∈RNand a.e.t∈ [0,T].Under suitable conditions only on F1,we prove that for any j∈Nthere existsεj 〉0such that if|ε|≤εj,then the above problem possesses at least jdistinct periodic solutions.