Time scales in linear delayed differential equations

The aim of this paper is to apply and justify the so-called aggregation of variables method for reduction of a complex system of linear delayed differential equations with two time scales: slow and fast. The difference between these time scales makes a parameter ε > 0 to appear in the formulation, being a mathematical problem of singular perturbations. The main result of this work consists of demonstrating that, under some hypotheses, the solution to the perturbed problem converges when ε→0 to the solution of an aggregated system whose construction is proposed. © 2005 Elsevier Inc. All rights reserved.