三阶微分方程组边值问题常号解的存在性

MULTIPLE CONSTANT-SIGN SOLUTIONS OF BVPS FOR THIRD-ORDER DIFFERENTIAL SYSTEMS

利用Krasnonel′skii′s不动点定理,结合Leray-Schauder抉择定理,研究下列三阶微分方程组边值问题um"i(t)=fi(t,u1(t),u2(t),...,un(t)), t∈[0,1],u′i(0)=u″i(0)=ui(1)=0, i=1,2,3,...,n在某些条件下常号解的存在性.