On the lowest possible dimension of supports of solutions to the discrete Schrodinger equation

Fuente: arXiv
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Main Author: Krymskii, Stanislav
Format: Preprint
Published: 2024
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author Krymskii, Stanislav
author_facet Krymskii, Stanislav
contents In this article we study the possible size of support of solutions to the discrete stationary Schrodinger equation $Δu(x)+V(x)u(x)=0$ in $\mathbb{Z}^d$. We show that for any nonzero solution to any discrete stationary Schrodinger equation the dimension of the support is at least $\log_2(d)-7.$ In the related setting of $\mathbb{Z}_2$-valued harmonic functions in $\mathbb{Z}^d$ one can improve the estimate on support's dimension to $\log_2(d).$ However, we also provide an example where a $\mathbb{Z}_2$-valued harmonic function in $\mathbb{Z}^d$ has a fractal-like support with dimension $\log_2(d)+1$. This fractal satisfies a recurrence relation: $$X = 2X+\{e_1,-e_1,\dots,e_d,-e_d\}.$$ This example and estimate provide an answer to the Malinnikova's question about the smallest size of set $X\subset\mathbb{Z}^d$ such that no cross contains exactly one point of $X$.
format Preprint
id arxiv_https___arxiv_org_abs_2401_02800
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the lowest possible dimension of supports of solutions to the discrete Schrodinger equation
Krymskii, Stanislav
Analysis of PDEs
In this article we study the possible size of support of solutions to the discrete stationary Schrodinger equation $Δu(x)+V(x)u(x)=0$ in $\mathbb{Z}^d$. We show that for any nonzero solution to any discrete stationary Schrodinger equation the dimension of the support is at least $\log_2(d)-7.$ In the related setting of $\mathbb{Z}_2$-valued harmonic functions in $\mathbb{Z}^d$ one can improve the estimate on support's dimension to $\log_2(d).$ However, we also provide an example where a $\mathbb{Z}_2$-valued harmonic function in $\mathbb{Z}^d$ has a fractal-like support with dimension $\log_2(d)+1$. This fractal satisfies a recurrence relation: $$X = 2X+\{e_1,-e_1,\dots,e_d,-e_d\}.$$ This example and estimate provide an answer to the Malinnikova's question about the smallest size of set $X\subset\mathbb{Z}^d$ such that no cross contains exactly one point of $X$.
title On the lowest possible dimension of supports of solutions to the discrete Schrodinger equation
topic Analysis of PDEs
url https://arxiv.org/abs/2401.02800