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In this paper, we address several interconnected problems in the theory of harmonic maps between Riemannian manifolds. First, we present necessary background and establish one of the main results of the paper: a criterion characterizing…

Differential Geometry · Mathematics 2025-07-14 Sergey Stepanov , Irina Tsyganok

We construct explicit complex-valued $p$-harmonic functions and harmonic morphisms on the classical compact symmetric complex and quaternionic Grassmannians. The ingredients for our construction method are joint eigenfunctions of the…

Differential Geometry · Mathematics 2023-08-22 Elsa Ghandour , Sigmundur Gudmundsson

We study consequences and applications of the folklore statement that every double complex over a field decomposes into so-called squares and zigzags. This result makes questions about the associated cohomology groups and spectral sequences…

Representation Theory · Mathematics 2021-04-07 Jonas Stelzig

We investigate an extended version of Hilbert space of analytic functions called Hilbert space of complex-valued harmonic functions. It is found that functions in Hilbert space of complex-valued harmonic functions exhibit many properties…

Complex Variables · Mathematics 2024-10-30 Tseganesh Getachew Gebrehana , Hunduma Legesse Geleta

Let $g:\mathbb{R}^2\to\mathbb{R}$ be a homogeneous polynomial of degree $p>1$, $G=(-g'_{y}, g'_{x})$ be its Hamiltonian vector field, and $G_t$ be the local flow generated by $G$. Denote by $E(G,O)$ the space of germs of $C^{\infty}$…

Dynamical Systems · Mathematics 2015-12-25 Sergiy Maksymenko

We~describe the Dirichlet space of $M$-harmonic functions, i.e.~functions annihilated by the invariant Laplacian on~the unit ball of the complex $n$-space, as~the limit of the analytic continuation (in~the spirit of Rossi and Vergne) of the…

Complex Variables · Mathematics 2024-03-15 Miroslav Engliš , El-Hassan Youssfi

Harmonic functions of two variables are exactly those that admit a conjugate, namely a function whose gradient has the same length and is everywhere orthogonal to the gradient of the original function. We show that there are also partial…

Differential Geometry · Mathematics 2014-04-23 Paul Baird , Michael Eastwood

Let $M$ be a smooth manifold. When $\Gamma$ is a group acting on the manifold $M$ by diffeomorphisms one can define the $\Gamma$-co-invariant cohomology of $M$ to be the cohomology of the differential complex…

Differential Geometry · Mathematics 2021-01-05 Mehdi Nabil

It is a well-known and elementary fact that a holomorphic function on a compact complex manifold without boundary is necessarily constant. The purpose of the present article is to investigate whether, or to what extent, a similar property…

Differential Geometry · Mathematics 2007-05-23 R. Feres , A. Zeghib

We explain a new phenomenon on non compact complete Riemannian four manifolds, where d^+ image of one forms can not exhaust densely on L^2 self dual forms on each compact subset, if a certain L^2 self dual harmonic form exists. This leads…

Differential Geometry · Mathematics 2020-01-07 Tsuyoshi Kato

In this paper we prove the analytic continuation of a two variable zeta function defined using the vector space of binary forms of degree $d$ to the entire two dimensional complex space as a meromorphic function.

Number Theory · Mathematics 2023-09-21 Eun Hye Lee , Ramin Takloo-Bighash

We prove that manifolds admitting a Riemannian metric for which products of harmonic forms are harmonic satisfy strong topological restrictions, some of which are akin to properties of flat manifolds. Others are more subtle, and are related…

Differential Geometry · Mathematics 2007-05-23 D. Kotschick

In this paper we generalize harmonic maps and morphisms to the \emph{degenerate semi-Riemannian category}, in the case when the manifolds $M$ and $N$ are \emph{stationary} and the map $\phi :M\to N$ is \emph{radical-preserving}. We…

Differential Geometry · Mathematics 2007-05-23 Alberto Pambira

We consider harmonic maps into pseudo-Riemannian manifolds. We show the removability of isolated singularities for continuous maps, i.e. that any continuous map from an open subset of R^m into a pseudo-Riemannian manifold which is two times…

Analysis of PDEs · Mathematics 2007-05-23 Frederic Helein

Let $h$ be a harmonic function defined on a spherical disk. It is shown that $\Delta^k |h|^2$ is nonnegative for all $k\in \mathbb{N}$ where $\Delta$ is the Laplace-Beltrami operator. This fact is generalized to harmonic functions defined…

Spectral Theory · Mathematics 2023-12-05 Gabor Lippner , Dan Mangoubi , Zachary McGuirk , Rachel Yovel

Consider a real-analytic orientable connected complete Riemannian manifold $M$ with boundary of dimension $n\ge 2$ and let $k$ be an integer $1\le k\le n$. In the case when $M$ is compact of dimension $n\ge 3$, we show that the manifold and…

Analysis of PDEs · Mathematics 2010-07-07 Katsiaryna Krupchyk , Matti Lassas , Gunther Uhlmann

In this paper we generalize a result in [1], showing that an arbitrary Riemannian symmetric space can be realized as a closed submanifold of a covering group of the Lie group defining the symmetric space. Some properties of the subgroups of…

Geometric Topology · Mathematics 2007-05-23 Jinpeng An , Zhengdong Wang

Let $\pi:(E,\nabla^{E}) \to (M,g)$ be an affine submersion with horizontal distribution, where $\nabla^{E}$ is a symmetric connection and $M$ is a Riemannian manifold. Let $\sigma$ be a section of $\pi$, namely, $\pi \circ \sigma = Id_{M}$.…

Differential Geometry · Mathematics 2009-12-14 S. N. Stelmastchuk

The spaces of Riemannian metrics on a closed manifold $M$ are studied. On the space ${\mathcal M}$ of all Riemannian metrics on $M$ the various weak Riemannian structures are defined and the corresponding connections are studied. The space…

Differential Geometry · Mathematics 2007-05-23 N. K. Smolentsev

An Hermitian bounded symmetric domain in a complex vector space, given in its circled realization, is endowed with two natural symplectic forms: the flat form and the hyperbolic form. In a similar way, the ambient vector space is also…

Differential Geometry · Mathematics 2008-12-13 Antonio J. Di Scala , Andrea Loi , Guy Roos