Abstract
We study the following nonlinear boundary-value problems for fractional differential equations: D. u(t) = f(t, v(t), D ss-1 v(t)), t > 0, D ss v(t) = g(t, u(t), D.-1 u(t)), t > 0, u > 0 and v > 0 in (0,1), lim t! 0+ u(t) = lim 0+ v(t) = 0, where 1 <.. 2 and 1 < ss. 2. Under certain conditions imposed on f and g, the existence of positive solutions is established by applying the Schauder fixed-point theorem.