S-asymptotically -periodic solutions of semilinear fractional integro-differential equations

We study S -asymptotically ω -periodic solutions of the semilinear fractional equation u ′ = ∂ − α + 1 A u + f ( t , u ) , 1 < α < 2 , considered in a Banach space X , where A is a linear operator of sectorial type μ < 0 .