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The existence and uniqueness of periodic solutions for a kind of Duffing-type equation with two deviating arguments. (English) Zbl 1205.34084
The Duffing-type delay differential equation $$x''(t) + f(x(t-\tau(t))) + g(x(t-\gamma(t))) = e(t)$$ is considered, where $\tau$, $\gamma$ and $e$ are real-valued continuous periodic functions with period $T$, $\tau'(t) <1$, $\gamma'(t) < 1$, $\int^T_0e(t)\,dt = 0$, and $f$ and $g$ are $C^1$ functions satisfying $f(c) + g(c) \not\equiv e(t)$ for all $t$ and $c$. Sufficient conditions are provided to ensure the existence, as well as uniqueness, of $T$-periodic solutions and it is claimed that these complement some known results.

##### MSC:
 34K13 Periodic solutions of functional differential equations
##### Keywords:
periodic solutions; Duffing equations; deviating arguments
Full Text:
##### References:
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