## Existence of positive solutions to second order Neumann boundary value problems.(English)Zbl 0963.34019

Summary: The existence of positive solutions to second-order Neumann boundary value problems $-u''+ Mu= f(t,u),\quad u'(0)= u'(1)= 0,$ and $u''+ Mu= f(t, u),\quad u'(0)= u'(1),$ is proved by a simple application of a fixed-point theorem in cones due to Krasnoselskij.

### MSC:

 34B18 Positive solutions to nonlinear boundary value problems for ordinary differential equations 34B15 Nonlinear boundary value problems for ordinary differential equations