Journal of Inequalities and Applications
Volume 2006 (2006), Article ID 42120, 22 pages

Oscillation and nonoscillation theorems for a class of even-order quasilinear functional differential equations

Jelena Manojlović1 and Tomoyuki Tanigawa2

1Department of Mathematics and Computer Science, Faculty of Science and Mathematics, University of Niš, Višegradska 33, Niš 18000, Serbia and Montenegro
2Department of Mathematics, Faculty of Science Education, Joetsu University of Education, Niigata 943-8512, Japan

Received 13 November 2005; Accepted 30 January 2006

Copyright © 2006 Jelena Manojlović and Tomoyuki Tanigawa. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We are concerned with the oscillatory and nonoscillatory behavior of solutions of even-order quasilinear functional differential equations of the type (|y(n)(t)|αsgny(n)(t))(n)+q(t)|y(g(t))|βsgny(g(t))=0, where α and β are positive constants, g(t) and q(t) are positive continuous functions on [0,), and g(t) is a continuously differentiable function such that g(t)>0, limtg(t)=. We first give criteria for the existence of nonoscillatory solutions with specific asymptotic behavior, and then derive conditions (sufficient as well as necessary and sufficient) for all solutions to be oscillatory by comparing the above equation with the related differential equation without deviating argument.