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From infinitesimal harmonic transformations to Ricci solitons

Sergey E. Stepanov, Irina I. Tsyganok, Josef Mikeš (2013)

Mathematica Bohemica

The concept of the Ricci soliton was introduced by R. S. Hamilton. The Ricci soliton is defined by a vector field and it is a natural generalization of the Einstein metric. We have shown earlier that the vector field of the Ricci soliton is an infinitesimal harmonic transformation. In our paper, we survey Ricci solitons geometry as an application of the theory of infinitesimal harmonic transformations.

Gap properties of harmonic maps and submanifolds

Qun Chen, Zhen Rong Zhou (2005)

Archivum Mathematicum

In this article, we obtain a gap property of energy densities of harmonic maps from a closed Riemannian manifold to a Grassmannian and then, use it to Gaussian maps of some submanifolds to get a gap property of the second fundamental forms.

Harmonic and Minimal Unit Vector Fields on the Symmetric Spaces G 2 and G 2 / S O ( 4 )

László Verhóczki (2012)

Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica

The exceptional compact symmetric spaces G 2 and G 2 / S O ( 4 ) admit cohomogeneity one isometric actions with two totally geodesic singular orbits. These singular orbits are not reflective submanifolds of the ambient spaces. We prove that the radial unit vector fields associated to these isometric actions are harmonic and minimal.

Harmonic maps and representations of non-uniform lattices of PU ( m , 1 )

Vincent Koziarz, Julien Maubon (2008)

Annales de l’institut Fourier

We study representations of lattices of PU ( m , 1 ) into PU ( n , 1 ) . We show that if a representation is reductive and if m is at least 2, then there exists a finite energy harmonic equivariant map from complex hyperbolic m -space to complex hyperbolic n -space. This allows us to give a differential geometric proof of rigidity results obtained by M. Burger and A. Iozzi. We also define a new invariant associated to representations into PU ( n , 1 ) of non-uniform lattices in PU ( 1 , 1 ) , and more generally of fundamental groups of orientable...

Harmonic maps and Riemannian submersions between manifolds endowed with special structures

Stere Ianuş, Gabriel Eduard Vîlcu, Rodica Cristina Voicu (2011)

Banach Center Publications

It is well known that Riemannian submersions are of interest in physics, owing to their applications in the Yang-Mills theory, Kaluza-Klein theory, supergravity and superstring theories. In this paper we give a survey of harmonic maps and Riemannian submersions between manifolds equipped with certain geometrical structures such as almost Hermitian structures, contact structures, f-structures and quaternionic structures. We also present some new results concerning holomorphic maps and semi-Riemannian...

Harmonic maps from compact Kähler manifolds with positive scalar curvature to Kähler manifolds of strongly seminegative curvature

Qilin Yang (2009)

Colloquium Mathematicae

It is well known there is no non-constant harmonic map from a closed Riemannian manifold of positive Ricci curvature to a complete Riemannian manifold with non-positive sectional curvature. If one reduces the assumption on the Ricci curvature to one on the scalar curvature, such a vanishing theorem does not hold in general. This raises the question: What information can we obtain from the existence of a non-constant harmonic map? This paper gives an answer to this problem when both manifolds are...

Harmonic metrics on four dimensional non-reductive homogeneous manifolds

Amirhesam Zaeim, Parvane Atashpeykar (2018)

Czechoslovak Mathematical Journal

We study harmonic metrics with respect to the class of invariant metrics on non-reductive homogeneous four dimensional manifolds. In particular, we consider harmonic lifted metrics with respect to the Sasaki lifts, horizontal lifts and complete lifts of the metrics under study.

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