We study the eigenvalue interval for the existence of positive solutions to a semipositone higher order fractional differential equation = = where , , , , satisfying , is the standard Riemann-Liouville derivative, , and is allowed to be changing-sign. By using reducing order method, the eigenvalue interval of existence for positive solutions is obtained.
Jing Wu. Xinguang Zhang. "Eigenvalue Problem of Nonlinear Semipositone Higher Order Fractional Differential Equations." Abstr. Appl. Anal. 2012 (SI06) 1 - 14, 2012. https://doi.org/10.1155/2012/740760