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We present a new method for manufacturing complex-valued harmonic morphisms from a wide class of Riemannian Lie groups. This yields new solutions from an important family of homogeneous Hadamard manifolds. We also give a new method for…

Differential Geometry · Mathematics 2010-05-24 Sigmundur Gudmundsson , Jonas Nordström

We investigate the structure of a harmonic morphism $F$ from a Riemannian 4-manifold M^4 to a 2-surface $N^2$ near a critical point $m_0$. If $m_0$ is an isolated critical point or if $M^4$ is compact without boundary, we show that $F$ is…

Differential Geometry · Mathematics 2013-07-16 Ali Makki , Marina Ville

We survey recent results in hermitian integral geometry, i.e. integral geometry on complex vector spaces and complex space forms. We study valuations and curvature measures on complex space forms and describe how the global and local…

Differential Geometry · Mathematics 2019-04-02 Andreas Bernig

There is a known hyperk\"ahler structure on any complexified Hermitian symmetric space $G/K$, whose construction relies on identifying $G/K$ with both a (co)adjoint orbit and the cotangent bundle to the compact Hermitian symmetric space…

Differential Geometry · Mathematics 2021-05-28 Ralph J. Bremigan

We collect the recent results on invariant f-structures in the generalized Hermitian geometry. Here the canonical f-structures on homogeneous k-symmetric spaces play a remarkable role. Specifically, these structures provide a wealth of…

Differential Geometry · Mathematics 2007-05-23 Vitaly V. Balashchenko

We complete the classification of six-dimensional strongly unimodular almost nilpotent Lie algebras admitting complex structures. For several cases we describe the space of complex structures up to isomorphism. As a consequence we determine…

Differential Geometry · Mathematics 2023-06-19 Anna Fino , Fabio Paradiso

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 almost Hermitian 4-manifolds with holonomy algebra, for the canonical Hermitian connection, of dimension at most one. We show how Riemannian 4-manifolds admitting five orthonormal symplectic forms fit therein and classify them. In…

Differential Geometry · Mathematics 2013-07-10 SImon G. Chiossi , Paul-Andi Nagy

Complex manifolds with compatible metric have a naturally defined subspace of harmonic differential forms that satisfy Serre, Hodge, and conjugation duality, as well as hard Lefschetz duality. This last property follows from a…

Differential Geometry · Mathematics 2020-01-17 Scott O. Wilson

We give an elementary proof of the fact that any 4-dimensional para-Hermitian manifold admits a unique para-Kaehler--Weyl structure. We then use analytic continuation to pass from the para-complex to the complex setting and thereby show any…

Differential Geometry · Mathematics 2012-10-26 Peter Gilkey , Stana Nikcevic

We present a comprehensive construction of scalar, vector and tensor harmonics on maximally symmetric three-dimensional spaces. Our formalism relies on the introduction of spin-weighted spherical harmonics and a generalized helicity basis…

General Relativity and Quantum Cosmology · Physics 2019-12-25 Cyril Pitrou , Thiago S. Pereira

We introduce and study properties of certain new multifunctional harmonic spaces in the upper halfspace.We prove several sharp embedding theorems for such multifunctional spaces,these results are new even in the case of a single function.

Functional Analysis · Mathematics 2013-01-08 Milos Arsenovic , Romi F. Shamoyan

These notes are concerned with harmonic and holomorphic functions on Euclidean spaces, using quaternions and Clifford algebras in higher dimensions. The main themes are weak solutions, the mean-value property, and subharmonicity.

Classical Analysis and ODEs · Mathematics 2007-05-23 Stephen Semmes

In this paper, a lot of examples of four-dimensional manifolds with an almost hypercomplex pseudo-Hermitian structure are constructed in several explicit ways. The received 4-manifolds are characterized by their linear invariants in the…

Differential Geometry · Mathematics 2012-05-08 Mancho Manev , Kouei Sekigawa

Pseudo-harmonic morphisms give rise on the domain space to a distribution which admits an almost complex structure compatible with the given Riemannian metric. We shall show that this property, together with the harmonicity, are preserved…

Differential Geometry · Mathematics 2007-05-23 Radu Slobodeanu

We study complex non-K\"ahler manifolds with Hermitian metrics being locally conformal to metrics with special cohomological properties. In particular, we provide examples where the existence of locally conformal holomorphic-tamed…

Differential Geometry · Mathematics 2016-08-04 Daniele Angella , Luis Ugarte

We study the problem of classifying the holomorphic $(m,n)$-subharmonic morphisms in complex space. This determines which holomorphic mappings preserves $m$-subharmonicity in the sense that the composition of the holomorphic mapping with a…

Complex Variables · Mathematics 2019-03-01 Per Ahag , Rafal Czyz , Lisa Hed

On a complex manifold $(M,J)$, we interpret complex symplectic and pseudo-K\"ahler structures as symplectic forms with respect to which $J$ is, respectively, symmetric and skew-symmetric. We classify complex symplectic structures on…

Differential Geometry · Mathematics 2025-03-26 Giovanni Bazzoni , Alejandro Gil-García , Adela Latorre

We consider and resolve the gap problem for almost quaternion-Hermitian structures, i.e. we determine the maximal and submaximal symmetry dimensions, both for Lie algebras and Lie groups, in the class of almost quaternion-Hermitian…

Differential Geometry · Mathematics 2020-08-19 Boris Kruglikov , Henrik Winther

K-Theory for hermitian symmetric spaces of non-compact type, as developed recently by the authors, allows to put Cartan's classification into a homological perspective. We apply this method to the case of inductive limits of finite…

K-Theory and Homology · Mathematics 2016-09-23 Dennis Bohle , Wend Werner