Existence of positive solutions for self-adjoint boundary-value problems with integral boundary conditions at resonance.
In this paper we deal with the four-point singular boundary value problem where , , , , , , , and may be singular at . By using the well-known theory of the Leray-Schauder degree, sufficient conditions are given for the existence of positive solutions.
In this paper we deal with the boundary value problem in the Hilbert space. Existence of a solutions is proved by using the method of lower and upper solutions. It is not necessary to suppose that the homogeneous problem has only the trivial solution. We use some results from functional analysis, especially the fixed-point theorem in the Banach space with a cone (Theorem 4.1, [5]).