“…On the other hand, there has been much more focus paid in developing the theory of existence and uniqueness of positive solutions for nonlinear FDEs have been investigated by using Leray-Schauder, coincidence degree theory, xed point index theory, xed point theorems in cones and so on, we refer the readers to [10,11,13,12,15,23,6,22,20,30]. For instance, N. Li and C. Wang in [22] studied the existence and uniqueness of positive solution for nonlinear FDE D θ 0+ φ(t) = f (t, φ(t)), 0 < t < 1, φ(0) = 0,…”