LINEARIZED OSCILLATIONS FOR DIFFERENTIAL-EQUATIONS OF NEUTRAL TYPE

Consider the nonlinear neutral delay differential equation [x(t) - P(t ) g(x(t - tau))]' + Q(t) h(x(t - sigma)) = 0 t greater than or equal t o t(0) with P(t), Q(t) continuous, tau > 0, sigma greater than or equa l to 0. We obtain new sufficient conditions for the oscillation of all solutions by an associate linear equation, and thereby establish some new criteria as proposed in an earlier open problem.