Symmetric twofold CR submanifolds in a Euclidean space
Minoru Kobayashi (1987)
Colloquium Mathematicae
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Minoru Kobayashi (1987)
Colloquium Mathematicae
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Alan Weinstein (2000)
Journal of the European Mathematical Society
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We define a distance between submanifolds of a riemannian manifold and show that, if a compact submanifold is not moved too much under the isometric action of a compact group , there is a -invariant submanifold -close to . The proof involves a procedure of averaging nearby submanifolds of riemannian manifolds in a symmetric way. The procedure combines averaging techniques of Cartan, Grove/Karcher, and de la Harpe/Karoubi with Whitney’s idea of realizing submanifolds as zeros...
Ze-Jun Hu, Guo-Xin Wei (2003)
Colloquium Mathematicae
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Let M̅ be a compact Riemannian manifold with sectional curvature satisfying (resp. ), which can be isometrically immersed as a hypersurface in the Euclidean space (resp. the unit Euclidean sphere). Then there exist no stable compact minimal submanifolds in M̅. This extends Shen and Xu’s result for 1/4-pinched Riemannian manifolds and also suggests a modified version of the well-known Lawson-Simons conjecture.
Kairen Cai (2003)
Colloquium Mathematicae
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Let M be a compact submanifold with parallel mean curvature vector embedded in the unit sphere . By using the Sobolev inequalities of P. Li to get estimates for the norms of certain tensors related to the second fundamental form of M, we prove some rigidity theorems. Denote by H and the mean curvature and the norm of the square length of the second fundamental form of M. We show that there is a constant C such that if , then M is a minimal submanifold in the sphere with sectional...
W. Slósarska, Z. Żekanowski (1972)
Colloquium Mathematicae
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Miroslava Petrović-Torgašev, Leopold C. A. Verstraelen (2008)
Archivum Mathematicum
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It was conjectured in [26] that, for all submanifolds of all real space forms , the Wintgen inequality is valid at all points of , whereby is the normalised scalar curvature of the Riemannian manifold and , respectively , are the squared mean curvature and the normalised scalar normal curvature of the submanifold in the ambient space , and this conjecture was shown there to be true whenever codimension . For a given Riemannian manifold , this inequality can be interpreted...
Paolo Piccinni (1984)
Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni
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Si considera la seconda forma fondamentale di foliazioni su varietà riemanniane e si ottiene una formula per il laplaciano - Se ne deducono alcune implicazioni per foliazioni su varietà a curvatura costante.
Shyamal K. Hui, Richard S. Lemence, Pradip Mandal (2020)
Commentationes Mathematicae Universitatis Carolinae
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A submanifold of a generalized Sasakian-space-form is said to be -totally real submanifold if and for all . In particular, if , then is called Legendrian submanifold. Here, we derive Wintgen inequalities on Legendrian submanifolds of generalized Sasakian-space-forms with respect to different connections; namely, quarter symmetric metric connection, Schouten-van Kampen connection and Tanaka-Webster connection.
Hai-Ping Fu (2016)
Annales Polonici Mathematici
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Let Mⁿ (n ≥ 3) be an n-dimensional complete super stable minimal submanifold in with flat normal bundle. We prove that if the second fundamental form A of M satisfies , where α ∈ [2(1 - √(2/n)), 2(1 + √(2/n))], then M is an affine n-dimensional plane. In particular, if n ≤ 8 and , d = 1,3, then M is an affine n-dimensional plane. Moreover, complete strongly stable hypersurfaces with constant mean curvature and finite -norm curvature in ℝ⁷ are considered.
Yan Zhao, Ximin Liu (2019)
Czechoslovak Mathematical Journal
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We give the definition of -biminimal submanifolds and derive the equation for -biminimal submanifolds. As an application, we give some examples of -biminimal manifolds. Finally, we consider -minimal hypersurfaces in the product space and derive two rigidity theorems.
Yaning Wang, Ximin Liu (2014)
Annales Polonici Mathematici
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We consider an almost Kenmotsu manifold with the characteristic vector field ξ belonging to the (k,μ)’-nullity distribution and h’ ≠ 0 and we prove that is locally isometric to the Riemannian product of an (n+1)-dimensional manifold of constant sectional curvature -4 and a flat n-dimensional manifold, provided that is ξ-Riemannian-semisymmetric. Moreover, if is a ξ-Riemannian-semisymmetric almost Kenmotsu manifold such that ξ belongs to the (k,μ)-nullity distribution, we prove...
Xi Guo and Lan Wu (2015)
Communications in Mathematics
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Let be an -dimensional submanifold in the unit sphere , we call a -extremal submanifold if it is a critical point of the functional . In this paper, we can study gap phenomenon for these submanifolds.
Oihane F. Blanco, Miguel Sánchez, José M. Senovilla (2013)
Journal of the European Mathematical Society
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, that is to say, Lorentzian manifolds with vanishing second derivative of the curvature tensor , are characterized by several geometric properties, and explicitly presented. Locally, they are a product where each factor is uniquely determined as follows: is a Riemannian symmetric space and is either a constant-curvature Lorentzian space or a definite type of plane wave generalizing the Cahen–Wallach family. In the proper case (i.e., at some point), the curvature...
Payel Karmakar (2022)
Mathematica Bohemica
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The present paper deals with the study of some properties of anti-invariant submanifolds of trans-Sasakian manifold with respect to a new non-metric affine connection called Zamkovoy connection. The nature of Ricci flat, concircularly flat, -projectively flat, -projectively flat, --projectively flat, pseudo projectively flat and -pseudo projectively flat anti-invariant submanifolds of trans-Sasakian manifold admitting Zamkovoy connection are discussed. Moreover, Ricci solitons on...