Singular perturbations for nonlinear Robin problems

In this paper, taking the study of radially symmetric solutions for Poisson equation as the background, we discuss the existence, uniqueness and asymptotic estimates of solutions of the singularly perturbed Robin problem for the general nonlinear second-order ordinary differential equation with a small parameter ϵ > 0: a(x, ϵ) y″ = ƒ(x, y, y′, ϵ), 0 < x < 1, a0y(0, ϵ) − b0y′(0, ϵ) = A0, a1y(1, ϵ) + b1y′1(1, ϵ) = A1.