NECESSARY AND SUFFICIENT CONDITIONS FOR OSCILLATION OF NONLINEAR NEUTRAL DIFFERENTIAL EQUATIONS
Tang Xianhua (Dept. of Applied Math., Central South University of Technology,Changsha 410083)
First we establish the equivalence of the oscillation of the following two dif- ferential equations and (r(t)y'(t))' + τ~(-1)f(t, r(t -σ1(t))y(t),..., r(t -σn(t))y(t)) = 0. (**) Next, we establish the necessary and sufficient conditions of all solutions to (*) being oscillatory, when f is strongly superlinear or strongly sublinear.