Existence of positive periodic solutions of neutral nonlinear differential systems with variable delays

Abstract

Hocine Gabsi1, Abdelouaheb Ardjouni2,∗ and Ahcene Djoudi3 1 Department of Mathematics, University of El-Oued, El-Oued, Algeria.; hocinegabsi@gmail.com 2 Department of Mathematics and Informatics, University of Souk Ahras, P.O. Box 1553, Souk Ahras, 41000, Algeria. 3 Applied Mathematics Lab, Faculty of Sciences, Department of Mathematics, University of Annaba, P.O. Box 12, Annaba 23000, Algeria.; adjoudi@yahoo.com * Correspondence: abd_ardjouni@yahoo.fr