Comenius University, Mlynsk\'a dolina, 842 15 Bratislava, Slovak Republic
E-mail: kubacek@fmph.uniba.sk
Abstract. It is proved that under some conditions the set of all solutions of an initial value problem for $n$-th order functional differential system on an unbounded interval is a compact $R_\delta$.
AMSclassification. 34K05, 34K25
Keywords. initial value problem, functional differential system, $R_\delta-set$