Disconjugacy of solutions of a second order differential equation with Colombeau generalized functions in coefficients
We consider a differential equation $$ Lx\doteq x''+P(t)x'+Q(t)x=0,\quad t\in[a, b]\subset \mathcal{I}\doteq(\alpha,\beta)\subset\mathbb{R}, \qquad(1) $$ 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 $$(\exists\, N\in\mathbb{N}) (\forall\, \varphi\in \mathcal{A}_N) (\exists\, \mu_0<1)\ \int_a^b|\mathcal{R}_P(\varphi_\mu,t)|\,dt+\int_a^b|\mathcal{R}_Q(\varphi_\mu,t)|\,dt<\frac{4}{b-a+4}\quad (0<\mu<\mu_0) $$ is satisfied, where $\varphi_{\mu}\doteq \frac{1}{\mu}\varphi \left(\frac{t}{\mu}\right)$, then the equation $(1)$ is disconjugate on $[a, b]$. We prove the separation theorem and its corollary.