On the existence of positive periodic solutions for neutral functional differential equation with multiple deviating arguments ✩

By means of the abstract continuation theory for k-contractions, some criteria are established for the existence and nonexistence of positive periodic solutions of the following neutral functional differential equation: dN dt = N(t) a(t) − β(t)N(t)− n j=1 bj (t)N t − σj (t ) − m i=1 ci (t)N t −τi (t ) .  2003 Elsevier Science (USA). All rights reserved