Positive solution of singular boundary value problems on a half-line (Q2508051)

This paper analyzes the existence of positive solutions of singular sub-linear boundary value problems on the half-line. It represents a generalization to singular nonlinearities of some results of a previous paper by \textit{S. Chen} and \textit{Y. Zhang}, appeared in J. Math. Anal. Appl. 195, 449--468 (1995; Zbl 0852.34019). The authors obtain necessary and sufficient conditions for the existence of positive continuous solutions or smooth solutions on \([0,\infty]\) by constructing new upper and lower solutions.