Almost periodic solutions of second-order neutral delay–differential equations with piecewise constant arguments ✩

In this paper, we present an existence theorem of almost periodic solutions of second-order neutral delay–differential equations with piecewise constant arguments of the form (x(t ) + x(t − 1)) = qx([t ]) + f (t), where [·] denotes the greatest integer function, q is a nonzero constant, and f (t) is almost periodic.  2004 Elsevier Inc. All rights reserved.