Positive solutions of singular and nonsingular Fredholm integral equations (Q1969993)

The authors consider the nonlinear Fredholm integral equation \[ y(t)=h(t)+ \int^T_0k(t,s) \biggl[f\bigl(y(s) \bigr)+g\bigl(y(s) \bigr)\biggr]ds, \quad t\in [0,T], \] where \(h\in C[0,T]\), \(f:[0,\infty) \to[0,\infty)\) is continuous and nondecreasing, \(g:(0,\infty) \to[0,\infty)\) is continuous and nonincreasing and possibly singular. Existence of nonnegative continuous solutions is proved with the help of Krasnoselskij's fixed point theorem.