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JOURNALS // Vestnik Udmurtskogo Universiteta. Matematika. Mekhanika. Komp'yuternye Nauki // Archive

Vestn. Udmurtsk. Univ. Mat. Mekh. Komp. Nauki, 2015 Volume 25, Issue 1, Pages 21–28 (Mi vuu461)

MATHEMATICS

Disconjugacy of solutions of a second order differential equation with Colombeau generalized functions in coefficients

I. G. Kim

Department of Mathematical Analysis, Udmurt State University, ul. Universitetskaya, 1, Izhevsk, 426034, Russia

Abstract: We consider a differential equation
\begin{equation} Lx\doteq x''+P(t)x'+Q(t)x=0,\qquad t\in[a, b]\subset\mathcal I\doteq(\alpha,\beta)\subset\mathbb R, \end{equation}
where $P,Q$ are $C$-generalized functions defined on $\mathcal I$ and are known as equivalence classes of Colombeau algebra. Let $\mathcal R_P$ and $\mathcal R_Q$ be representatives of $P$ and $Q$ respectively, $\mathcal A_N$ are classes of functions with compact support used to define Colombeau algebra. We obtain new sufficient conditions for disconjugacy of the equation (1). We prove that if the condition
\begin{equation*} (\exists N\in\mathbb N)\,(\forall\varphi\in\mathcal A_N)\,(\exists\mu_0<1)\ \int_a^b|\mathcal R_P(\varphi_\mu,t)|\,dt+\int_a^b|\mathcal R_Q(\varphi_\mu,t)|\,dt<\frac4{b-a+4}\quad(0<\mu<\mu_0), \end{equation*}
is satisfied, where $\varphi_\mu\doteq\frac1\mu\varphi\left(\frac t\mu\right)$, then the equation (1) is disconjugate on $[a,b]$. We prove the separation theorem and its corollary.

Keywords: $C$-generalized function, $C$-generalized number, weak equation, disconjugacy.

UDC: 517.917

MSC: 46F30

Received: 18.01.2015



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