The authors consider singular boundary value problems (BVP) of nonlinear second-order differential equations (1) , (2) , , (3) , . In (2) the limit is a constant not previously given, but in (3) is a given constant.
The main methods used in the article are upper and lower solution techniques. Necessary and sufficient conditions for the existence of a solution to a class of sublinear singular boundary value problems are obtained. As an application the authors consider a singular BVP that arises in nonlinear mechanics.