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**Remarks on the uniqueness of second order ODEs.**
*(English)*
Zbl 1224.34008

Summary: We are concerned with the uniqueness problem for solutions to the second order ODE of the form \(x''+f(x,t)=0\), subject to appropriate initial conditions under the unique assumption that \(f\) is non-decreasing with respect to \(x\) for each \(t\) fixed. We show that there is non-uniqueness in general. On the other hand, several types of reasonable additional assumptions make the problem uniquely solvable. The interest in this problem comes, among others, from the study of oscillations of lumped parameter systems with implicit constitutive relations.

### MSC:

34A12 | Initial value problems, existence, uniqueness, continuous dependence and continuation of solutions to ordinary differential equations |

### References:

[1] | P. Hartman: Ordinary Differential Equations. 2nd ed. with some corrections and additions. S.M. Hartman, Baltimore, 1973. · Zbl 0281.34001 |

[2] | L. Meirovitch: Elements of Vibration Analysis. Second edition. McGraw-Hill, New York, 1986. · Zbl 0359.70039 |

[3] | D. Pražák, K.R. Rajagopal: Mechanical oscillators described by a system of differential-algebraic equations. Submitted. |

[4] | K.R. Rajagopal: A generalized framework for studying the vibration of lumped parameter systems. Submitted. |

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