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We show that geometric disorder leads to purely singular continuous spectrum generically. The main input is a result of Simon known as the ``Wonderland theorem''. Here, we provide an alternative approach and actually a slight strengthening…

Mathematical Physics · Physics 2007-05-23 Daniel Lenz , Peter Stollmann

In this note, we prove that the infimum of the mean curvature on any disconnected boundary component of an unbounded mean convex domain in $\mathbb{R}^n$ must be zero.

Differential Geometry · Mathematics 2026-05-19 Jian Ge

In this note, we characterize the sharp boundary condition such that the fractional harmonic extensions with H\"older regularity up to the boundary is globally H\"older continuous. The proofs are based on estimates of fractional harmonic…

Analysis of PDEs · Mathematics 2025-08-19 Feng Li

Let $E\subset \mathbb{R}^{n+1}$, $n\ge 2$, be an Ahlfors-David regular set of dimension $n$. We show that the weak-$A_\infty$ property of harmonic measure, for the open set $\Omega:= \mathbb{R}^{n+1}\setminus E$, implies uniform…

Classical Analysis and ODEs · Mathematics 2018-10-10 Steve Hofmann , Phi Le , José María Martell , Kaj Nyström

We obtain an integral inequality for asymptotically linear harmonic functions on asymptotically flat 3-manifolds with noncompact boundary, which implies positivity of a convex combination of ADM masses of two conformally related metrics…

Differential Geometry · Mathematics 2025-12-04 Alex Freire , Mohammad Tariquel Islam

Let $E\subset \mathbb{R}^{n+1}$, $n\ge 2$, be a closed, Ahlfors-David regular set of dimension $n$ satisfying the "Riesz Transform bound" $$\sup_{\varepsilon>0}\int_E\left|\int_{\{y\in E:|x-y|>\varepsilon\}}\frac{x-y}{|x-y|^{n+1}} f(y)…

Classical Analysis and ODEs · Mathematics 2016-08-28 Steve Hofmann , José María Martell , Svitlana Mayboroda

We give a sufficient condition for a Borel subset $E\subset X$ of a complete metric space with $\mathcal{H}^n(E)<\infty$ to be $n$-rectifiable. This condition involves a decomposition of $E$ into rectifiable curves known as an Alberti…

Metric Geometry · Mathematics 2025-01-07 David Bate , Julian Weigt

In a recent paper, Cs\"ornyei and Wilson prove that curves in Euclidean space of $\sigma$-finite length have tangents on a set of positive $\mathscr{H}^{1}$-measure. They also show that a higher dimensional analogue of this result is not…

Classical Analysis and ODEs · Mathematics 2016-12-30 Jonas Azzam

The present paper, along with its sequel, establishes the correspondence between the properties of the solutions of a class of PDEs and the geometry of sets in Euclidean space. We settle the question of whether (quantitative) absolute…

Analysis of PDEs · Mathematics 2020-01-15 Steve Hofmann , José María Martell , Svitlana Mayboroda , Tatiana Toro , Zihui Zhao

One can describe isomorphism of two compact hyperbolic Riemann surfaces of the same genus by a measure-theoretic property: a chosen isomorphism of their fundamental groups corresponds to a homeomorphism on the boundary of the Poincar\'e…

Algebraic Geometry · Mathematics 2011-12-22 Gunther Cornelissen , Janne Kool

Absolute continuity implies uniform continuity, but generally not vice versa. In this short note, we present one sufficient condition for a uniformly continuous function to be absolutely continuous, which is the following theorem: For a…

Classical Analysis and ODEs · Mathematics 2015-03-17 Kai Yang , Chenhong Zhu

We generalize the Arzel\`a-Ascoli theorem in the space of continuous maps on a compact interval with values in Euclidean N-space by providing a quantitative link between the Hausdorff measure of noncompactness in this space and a natural…

Functional Analysis · Mathematics 2013-03-15 Ben Berckmoes

Rademacher theorem states that every Lipschitz function on the Euclidean space is differentiable almost everywhere, where "almost everywhere" refers to the Lebesgue measure. In this paper we prove a differentiability result of similar type,…

Classical Analysis and ODEs · Mathematics 2015-03-27 Giovanni Alberti , Andrea Marchese

A generalized divergence theorem is established allowing for domains with inner boundaries. The normal trace of a rough integrand is not a Radon measure; rather, the boundary integral is expressed via a surface functional continuous with…

Analysis of PDEs · Mathematics 2025-10-29 Thomas Ruf

We prove that a generic area-preserving diffeomorphism of a compact surface with non-empty boundary has an equidistributed set of periodic orbits. This implies that such a diffeomorphism has a dense set of periodic points, although we also…

Symplectic Geometry · Mathematics 2023-10-23 Abror Pirnapasov , Rohil Prasad

We prove the following. If $f$ is a harmonic quasiconformal mapping between the unit ball in $\mathbb{R}^n$ and a spatial domain with $C^{1,\alpha}$ boundary, then $f$ is Lipschitz continuous in $B$. This generalizes some known results for…

Analysis of PDEs · Mathematics 2021-03-19 Anton Gjokaj , David Kalaj

In the present paper, homeomorphisms in metric spaces which generalize quasiconformal mappings, are investigated. It is proved that, at some conditions on metric spaces and boundaries of corresponding domains, families of above mappings are…

Metric Geometry · Mathematics 2017-10-10 Evgeny Sevost'yanov

Given a harmonic measure of a hyperbolic lamination on a compact metric space, a positive harmonic function is defined on the universal cover of a typical leaves. We discuss some properties of this function. Especially if all the leaves are…

Geometric Topology · Mathematics 2013-06-06 Shigenori Matsumoto

We show that for a uniformly elliptic divergence form operator $L$, defined in an open set $\Omega$ with Ahlfors-David regular boundary, BMO-solvability implies scale invariant quantitative absolute continuity (the weak-$A_\infty$ property)…

Analysis of PDEs · Mathematics 2016-07-05 Steve Hofmann , Phi Le

We prove the existence of nontrivial unbounded exceptional domains in the Euclidean space $\R^N$, $N\geq4$. These domains arise as perturbations of complements of straight cylinders in $\R^N$, and by definition they support a positive…

Analysis of PDEs · Mathematics 2023-06-21 Ignace Aristide Minlend , Tobias Weth , Jing Wu