Academic Editor: Allan C. Peterson
Copyright © 2010 Jaromír Baštinec et al. 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.
New nonoscillation and oscillation criteria are derived for scalar delay differential equations and
and in the critical case including equations with several unbounded delays,
without the usual assumption that the parameters
and of the equations are continuous functions. These conditions improve and extend some known oscillation results in the critical case for delay differential equations.