## On oscillation criteria for third order nonlinear delay differential equations.(English)Zbl 1212.34189

Summary: We are concerned with the oscillation of third order nonlinear delay differential equations of the form $(r_{2}(t) (r_{1}(t) x')')'+p(t) x'+q(t) f(x(g(t))) =0.$ We establish some new sufficient conditions which insure that every solution of this equation either oscillates or converges to zero.

### MSC:

 34K11 Oscillation theory of functional-differential equations

### Keywords:

third order; functional differential equation
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