Abstract
This paper is concerned with the oscillation of the first order linear delay differential equation x' (t) + q(t)x(tau(t)) = 0, t >= t(0), where q, tau is an element of C([t(0),infinity), [0,infinity)), tau(t) <= t, such that lim (tau(t))(t ->infinity) = infinity. Several new oscillation criteria of iterative and non-iterative types are obtained. Two examples are presented to show the strength and applicability of these criteria over known ones.