Triple positive solutions for nonlocal fractional differential equations with singularities both on time and space variables

In this paper, different height functions of the nonlinear term on special bounded sets together with Leggett-Williams and Krasnosel'skii fixed point theorems are employed to establish the existence of triple positive solutions for a class of higher-order fractional differential equations with integral conditions. The singularities are with respect not only to the time but also to the space variables.