Boundary Value Problems
Volume 2009 (2009), Article ID 540863, 20 pages
doi:10.1155/2009/540863
Recent existence results for second-order singular periodic differential equations
Jifeng Chu1
and Juan J. Nieto2
1Department of Mathematics, College of Science, Hohai University, Nanjing 210098, China
2Departamento de Análisis Matemático, Facultad de Matemáticas, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
Abstract
We present some recent existence results for second-order singular periodic differential equations. A nonlinear alternative principle of Leray-Schauder type, a well-known fixed point theorem in cones, and Schauder's fixed point theorem are used in the proof. The results shed some light on the differences between a strong singularity and a weak singularity.