Warped products, solid hyperbolic fillings, and the identity $D^{1,p} = N^{1,p} + \mathbb{R}$

Fuente: arXiv
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Main Authors: Kangasniemi, Ilmari, Kline, Josh, Shanmugalingam, Nageswari, Speight, Gareth
Format: Preprint
Published: 2025
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author Kangasniemi, Ilmari
Kline, Josh
Shanmugalingam, Nageswari
Speight, Gareth
author_facet Kangasniemi, Ilmari
Kline, Josh
Shanmugalingam, Nageswari
Speight, Gareth
contents We construct a large class of metric measure spaces $Z$ which satisfy the identity $D^{1,p}(Z) = N^{1,p}(Z) + \mathbb{R}$, i.e.\ any measurable function $u \colon Z \to \mathbb{R}$ with an $L^p$-integrable upper gradient is a constant term away from being $L^p$-integrable. To do so, we construct a family of hyperbolic fillings $\mathbb{H}_{α, β}(Y)$, $α, β\in (0, \infty)$, of a metric measure space $Y$, via a warped product of $Y$ with an exponentially weighted positive real line. We then show that for certain classes of $Y$, the above identity is satisfied for $Z=\mathbb{H}_{α,β}(Y)$ when $1\le p\le β/α$. We also show that under mild assumptions on $Y$, the warped product $\mathbb{H}_{α, β}(Y)$ is Gromov hyperbolic as a metric space and the Gromov boundary of $\mathbb{H}_{α, β}(Y)$ is quasisymmetric to $Y$.
format Preprint
id arxiv_https___arxiv_org_abs_2508_01857
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Warped products, solid hyperbolic fillings, and the identity $D^{1,p} = N^{1,p} + \mathbb{R}$
Kangasniemi, Ilmari
Kline, Josh
Shanmugalingam, Nageswari
Speight, Gareth
Metric Geometry
Analysis of PDEs
46E36, 30L15, 53C23
We construct a large class of metric measure spaces $Z$ which satisfy the identity $D^{1,p}(Z) = N^{1,p}(Z) + \mathbb{R}$, i.e.\ any measurable function $u \colon Z \to \mathbb{R}$ with an $L^p$-integrable upper gradient is a constant term away from being $L^p$-integrable. To do so, we construct a family of hyperbolic fillings $\mathbb{H}_{α, β}(Y)$, $α, β\in (0, \infty)$, of a metric measure space $Y$, via a warped product of $Y$ with an exponentially weighted positive real line. We then show that for certain classes of $Y$, the above identity is satisfied for $Z=\mathbb{H}_{α,β}(Y)$ when $1\le p\le β/α$. We also show that under mild assumptions on $Y$, the warped product $\mathbb{H}_{α, β}(Y)$ is Gromov hyperbolic as a metric space and the Gromov boundary of $\mathbb{H}_{α, β}(Y)$ is quasisymmetric to $Y$.
title Warped products, solid hyperbolic fillings, and the identity $D^{1,p} = N^{1,p} + \mathbb{R}$
topic Metric Geometry
Analysis of PDEs
46E36, 30L15, 53C23
url https://arxiv.org/abs/2508.01857