Electronic Journal of Differential Equations,
Vol. 2007(2007), No. 99, pp. 1-10.

Title: Almost periodic solutions for higher-order Hopfield neural
       networks without bounded activation functions

Authors: Fuxing Zhang (Shaoyang Univ., Hunan, China)
         Ya Li  (Hunan Univ., Changsha, China)

Abstract:
 In this paper, we consider  higher-order Hopfield neural networks
 (HHNNs) with time-varying delays. Based on the fixed point theorem,
 Lyapunov functional method, differential inequality techniques,
 and without assuming the boundedness on the activation functions,
 we establish sufficient conditions for the existence and local
 exponential stability of the almost periodic solutions.
 The results of this paper are new and they complement previously
 known results.

Submitted March 11, 2007. Published July 13, 2007.
Math Subject Classifications: 34C25, 34K13.
Key Words: High-order Hopfield neural networks; almost periodic solution; 
           exponential stability; time-varying delays.