Normal flows and harmonic manifolds.
González-Dávila, J.C., Vanhecke, Lieven (1997)
Publications de l'Institut Mathématique. Nouvelle Série
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González-Dávila, J.C., Vanhecke, Lieven (1997)
Publications de l'Institut Mathématique. Nouvelle Série
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Andrzej Derdzinski (1980)
Mathematische Zeitschrift
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Harold Donnelly (1986)
Mathematische Zeitschrift
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Qilin Yang (2009)
Colloquium Mathematicae
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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...
Yukio Otsu (1991)
Mathematische Zeitschrift
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Jing Mao (2016)
Czechoslovak Mathematical Journal
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In this paper, for complete Riemannian manifolds with radial Ricci or sectional curvature bounded from below or above, respectively, with respect to some point, we prove several volume comparison theorems, which can be seen as extensions of already existing results. In fact, under this radial curvature assumption, the model space is the spherically symmetric manifold, which is also called the generalized space form, determined by the bound of the radial curvature, and moreover, volume...
Andrzej Derdzinski (1982)
Mathematische Annalen
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Yaning Wang (2016)
Open Mathematics
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Let M3 be a three-dimensional almost Kenmotsu manifold satisfying ▽ξh = 0. In this paper, we prove that the curvature tensor of M3 is harmonic if and only if M3 is locally isometric to either the hyperbolic space ℍ3(-1) or the Riemannian product ℍ2(−4) × ℝ. This generalizes a recent result obtained by [Wang Y., Three-dimensional locally symmetric almost Kenmotsu manifolds, Ann. Polon. Math., 2016, 116, 79-86] and [Cho J.T., Local symmetry on almost Kenmotsu three-manifolds, Hokkaido...
Paweł Grzegorz Walczak (1984)
Banach Center Publications
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Helmut Kaul, Stefan Hildebrandt, Kjell-Ove Widman (1975)
Mathematica Scandinavica
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Barbara Opozda (1983)
Annales Polonici Mathematici
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Yunhee Euh, Jeong Hyeong Park, Kouei Sekigawa (2017)
Czechoslovak Mathematical Journal
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We derive a curvature identity that holds on any 6-dimensional Riemannian manifold, from the Chern-Gauss-Bonnet theorem for a 6-dimensional closed Riemannian manifold. Moreover, some applications of the curvature identity are given. We also define a generalization of harmonic manifolds to study the Lichnerowicz conjecture for a harmonic manifold “a harmonic manifold is locally symmetric” and provide another proof of the Lichnerowicz conjecture refined by Ledger for the 4-dimensional...
M.T. Anderson, J. Cheeger (1991)
Geometric and functional analysis
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