Advances in Difference Equations 
Volume 2005 (2005), Issue 3, Pages 215-226
doi:10.1155/ADE.2005.215

Periodic solutions for a coupled pair of delay difference equations

Guang Zhang,1 Shugui Kang,2 and Sui Sun Cheng3

 1Department of Mathematics, Qingdao Technological University, Shandong, Qingdao 266033, China
2Department of Mathematics, Yanbei Normal University, Shanxi, Datong 037000, China
3Department of Mathematics, National Tsing Hua University, Hsinchu 300, Taiwan
Received 31 January 2005; Revised 24 March 2005

Abstract

Based on the fixed-point index theory for a Banach space, positive periodic solutions are found for a system of delay difference equations. By using such results, the existence of nontrivial periodic solutions for delay difference equations with positive and negative terms is also considered.