arXiv research

Families of hypersurfaces that are level-set families of harmonic functions free of critical points are characterized by a local differential-geometric condition. Harmonic functions with a specified level-set family are constructed from geometric data. As a by-product, it is shown that the evolution of the gradient of …

Study on harmonic functions on nonnegative curvature 3D manifolds.

Proves positive mass theorem for 3-manifolds with a boundary.

Proves a function's locally least gradient property if its level sets are minimal laminations.

Find conditions for starshapedness of level sets in Heisenberg group.

New methods using spacetime harmonic functions solve geometric inequalities.

Study on isoperimetric inequalities and regularity of $A$-harmonic functions on surfaces.

A simple formula is derived for the Ricci scalar curvature of any smooth level set ${ψ(x_0,x_1,...,x_n)=C}$ embedded in the Euclidean space $\mathbb R^{n+1}$, in terms of the gradient $\nablaψ$ and the Laplacian $Δψ$. Some applications are given to the geometry of low-dimensional $p$-harmonic functions and high-dime…

The paper studies conditions for graphs connecting level sets of harmonic polynomials.

The paper proves a geometric capacitary inequality for sub-static manifolds with harmonic potentials.

We prove the following theorem. Let $U$ be a pseudo-harmonic function on a surface $M^2$. For a real valued continuous function $V : M^2 \to {\mathbb R}$ to be a conjugate pseudo-harmonic function of $U$ on $M^2$ it is necessary and sufficient that $V$ is open on level sets of $U$.

Study on 3-manifolds with nonnegative scalar curvature and positive harmonic functions.

Motivated by a question of Rubel, we consider the problem of characterizing which noncompact hypersurfaces in $\RR^n$ can be regular level sets of a harmonic function modulo a $C^\infty$ diffeomorphism, as well as certain generalizations to other PDEs. We prove a versatile sufficient condition that shows, in particular…

In this paper we describe the notion of an annular end of a Riemann surface being of finite type with respect to some harmonic function and prove some theoretical results relating the conformal structure of such an annular end to the level sets of the harmonic function. We then apply these results to understand and cha…

We continue the study of the variation of the $p$--modulus of a foliation initiated by the first author. We derive the formula for the second variation which allows to study $p$--stable foliations. We obtain some results concerning codimension one $p$--stable foliations. Moreover, we derive the equation for the critica…

Paper excludes the lowest energy level as an accumulation point for harmonic maps into analytic manifolds.

In the present paper we study two-dimensional maximal surfaces with harmonic level-sets. As a corollary we obtain a new class of one-periodic maximal surfaces.

An explicit lower bound for the mass of an asymptotically flat Riemannian 3-manifold is given in terms of linear growth harmonic functions and scalar curvature. As a consequence, a new proof of the positive mass theorem is achieved in dimension three. The proof has parallels with both the Schoen-Yau minimal hypersurfac…

It is known that the $L^{2}$-norms of a harmonic function over spheres satisfies some convexity inequality strongly linked to the Almgren's frequency function. We examine the $L^{2}$-norms of harmonic functions over a wide class of evolving hypersurfaces. More precisely, we consider compact level sets of smooth regular…

On some specified convex supporting sets of spheres, we find a generalized longitude function whose level sets are totally geodesic. Given an arbitrary (weakly) harmonic map into spheres, the composition of the generalized longitude function and harmonic map satisfies an elliptic equation of divergence type. With the a…

For a harmonic function u on Euclidean space, this note shows that its gradient is essentially determined by the geometry of its level hypersurfaces. Specifically, the factor by which |grad(u)| changes along a gradient flow is completely determined by the mean curvature of the level hypersurfaces intersecting the flow.

Let $M$ be a compact, connected Riemannian manifold whose Riemannian volume measure is denoted by $σ$. Let $f: M \rightarrow \mathbb{R}$ be a non-constant eigenfunction of the Laplacian. The random wave conjecture suggests that in certain situations, the value distribution of $f$ under $σ$ is approximately Gaussian. Wr…

The paper proves a spacetime version of dihedral rigidity for cubes in 3D spacetime.

Study on lengths and curvatures of harmonic functions on smooth and singular surfaces.

We give a lower bound for the Lorentz length of the ADM energy-momentum vector (ADM mass) of 3-dimensional asymptotically flat initial data sets for the Einstein equations. The bound is given in terms of linear growth `spacetime harmonic functions' in addition to the energy-momentum density of matter fields, and is val…

Researchers prove a Penrose inequality for spacetime with specific conditions.

Paper proves stronger Penrose inequality with matter density.

Paper shows non-convexity in solutions to Hessian equations.

Rigidity theorem shows massless hyperboloidal data embeds into Minkowski space.

Stability of positive mass theorem proven under Ricci curvature bounds.

The paper proves energy theorems for specific initial data sets in 3D spacetime.

Willmore surfaces are the extremals of the Willmore functional (possibly under a constraint on the conformal structure). With the characterization of Willmore surfaces by the (possibly perturbed) harmonicity of the mean curvature sphere congruence [Blaschke, Ejiri, Rigoli, Burstall-Calderbank], a zero-curvature formula…

Study rigidifies geometry of electrostatic systems with specific tensor properties.

In this paper we generalize the monotonicity formulas of [C] for manifolds with nonnegative Ricci curvature. Monotone quantities play a key role in analysis and geometry; see, e.g., [A], [CM1] and [GL] for applications of monotonicity to uniqueness. Among the applications here is that level sets of Green's function on …

The paper proves geodesics and conic sections are length-minimizing under specific metrics.

For a homotopically energy-minimizing map $u: N^3\to S^1$ on a compact, oriented $3$-manifold $N$ with boundary, we establish an identity relating the average Euler characteristic of the level sets $u^{-1}\{θ\}$ to the scalar curvature of $N$ and the mean curvature of the boundary $\partial N$. As an application, we ob…

Let $U(\boldsymbol r),\boldsymbol r\inΩ\subset \mathbb R^2$ be a harmonic function that solves an exterior Dirichlet problem. If all the level sets of $U(\boldsymbol r),\boldsymbol r\inΩ$ are smooth Jordan curves, then there are several geometric inequalities that correlate the curvature $κ(\boldsymbol r)$ with the ma…

The paper extends Hodge-de Rham theory to higher-dimensional Sierpinski gaskets.

For a harmonic map $u:M^3\to S^1$ on a closed, oriented $3$--manifold, we establish the identity $2π\int_{θ\in S^1}χ(Σ_θ)\geq \frac{1}{2}\int_{θ\in S^1}\int_{Σ_θ}(|du|^{-2}|Hess(u)|^2+R_M)$ relating the scalar curvature $R_M$ of $M$ to the average Euler characteristic of the level sets $Σ_θ=u^{-1}\{θ\}$. As our prima…

Study examines harmonic functions in sub-Riemannian and RCD settings.

New proof of Positive Mass Theorem using Green's function and monotonicity formula.

We find a class of minimal hypersurfaces H(k) as the zero level set of Pfaffians, resp. determinants of real 2k+2 dimensional antisymmetric matrices. While H(1) and H(2) are congruent to a 6-dimensional quadratic cone resp. Hsiang's cubic su(4) invariant in R15, H(k>2) (special harmonic so(2k+2)-invariant cones of degr…

New metrics produce discrete zero sets for nondegenerate harmonic forms.

Proves rigidity of SU(2) and SO(3) quantum representations at prime levels.

Researchers find second-order estimates for $p$-Laplacian in RCD spaces.

The paper studies harmonic maps to the circle with complex singular sets.

In this paper we show the existence of weak solutions $w : M \rightarrow \mathbb{R}$ of the inverse mean curvature flow starting from a relatively compact set (possibly, a point) on a large class of manifolds satisfying Ricci lower bounds. Under natural assumptions, we obtain sharp estimates for the growth of $w$ and f…

Existence of harmonic maps near projections in hyperbolic spaces for large convex sets.