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
DOI:
10.20537/vm150103