English

Admissible pair of spaces for not correctly solvable linear differential equations

Classical Analysis and ODEs 2014-09-30 v1

Abstract

We consider the differential equation \begin{align}\label{ab} -y'(x)+q(x)y(x)=f(x), \quad x \in \mathbb R, \end{align} where fLp(R)f \in L_{p}(\mathbb R), p[1,)p\in [1,\infty), and 0qL1loc(R)0\leq q \in L_{1}^{\rm loc}(\mathbb R), 0q(t)dt=0q(t)dt=,\int\limits_{-\infty}^{0}q(t)\,dt=\int\limits_{0}^{\infty}q(t)\,dt=\infty, \begin{align*} q_{0}(a)=\inf_{x\in \mathbb R}\int_{x-a}^{x+a}q(t)\,dt=0 \quad{\rm \ for ~ any }\quad a\in (0,\infty). \end{align*} Under these conditions, the equation ({\rm \ref{ab}}) is not correctly solvable in Lp(R)L_{p}(\mathbb R) for any p[1,)p \in [1, \infty) . Let q(x)q^{*}(x) be the Otelbaev-type average of the function q(t),tRq(t), t\in \mathbb{R}, at the point t=xt=x; θ(x)\theta(x) be a continuous positive function for xRx \in \mathbb R, and \begin{align*} L_{p,\theta }(\mathbb R) = \{f\in L_{p}^{\rm loc}(\mathbb R):\, \int_{-\infty}^{\infty}|\theta(x)f(x)|^{p}\,dx<\infty \}, \end{align*} \begin{align*} \|f\|_{L_{p,\theta}(\mathbb R)}=\left(\int_{-\infty}^{\infty}|\theta(x)f(x)|^{p}\,dx\right)^{1/p}\ \end{align*} We show that if there exists a constant c[1,)c\in [1, \infty), such that the inequality c1q(x)θ(x)cq(x)c^{-1}q^{*}(x)\leq \theta(x)\leq cq^{*}(x) holds for all xRx \in \mathbb{R}, then under some additional conditions for qq the pair of spaces {Lp,θ(R);Lp(R)}\{L_{p, \theta}(\mathbb R); L_{p}(\mathbb R)\} is admissible for the equation ({\rm \ref{ab}}).

Keywords

Cite

@article{arxiv.1409.7823,
  title  = {Admissible pair of spaces for not correctly solvable linear differential equations},
  author = {N. Chernyavskaya and L. Dorel and L. Shuster},
  journal= {arXiv preprint arXiv:1409.7823},
  year   = {2014}
}