## Oscillation criteria for second-order nonlinear differential equations with damping.(English)Zbl 0977.34027

The authors consider second-order nonlinear differential equations with damping of the form $(a(t)\Psi(x)x')'+p(t)x'+q(t)f(x)=0,\quad t\geq t_0,$ where $$p$$ and $$q$$ are allowed to change signs. Using Philos’ technique some new oscillatory criteria are established.

### MSC:

 34C10 Oscillation theory, zeros, disconjugacy and comparison theory for ordinary differential equations 34C15 Nonlinear oscillations and coupled oscillators for ordinary differential equations

### Keywords:

oscillation; damping