New Kamenev-type oscillation criteria for second order neutral nonlinear differential equations

In this paper, some new oscillation criteria for second order neutral nonlinear differential equation[r(t)(y(t)+p(t)y(σ(t)))′]′+∑i=1nqi(t)fi(y(τi(t)))=0,t⩾t0are established. New oscillation criteria are different from most known ones in the sense that they are based on a class of new functions Φ(t, s, l) defined in the sequel. Our results are sharper than some previous results which can be seen by the example at the end of this paper.