Results 1 to 10 of about 132,930 (155)
On the sectional curvature of compact hypersurfaces [PDF]
Proceedings of the American Mathematical Society, 1990 We establish a sufficient condition for compact hypersurfaces of a complete riemannian manifold to be spherical. It is well known, from the works of Jacobowitz, Jorge and Koutroufiotis, and others, that the maximum sectional curvature of such hypersurfaces can be estimated from the curvature of the ambient space and the outer radius.
Leslie Coghlan, Yoe Itokawa
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A sectional curvature for statistical structures
Linear Algebra and its Applications, 2016 19 ...
Opozda, Barbara
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Group-Quotients with Positive Sectional Curvatures [PDF]
Proceedings of the American Mathematical Society, 1977 Let H be a closed subgroup of compact Lie group G. A necessary and sufficient condition is obtained for the existence of a left-invariant Riemannian metric on G such that the subduced metric on the quotient H G has strictly positive sectional curvatures.
Robert Geroch
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SECTIONAL CURVATURES OF GRASSMANN MANIFOLDS [PDF]
Proceedings of the National Academy of Sciences, 1968 Yung-Chow Wong
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Four-manifolds of pinched sectional curvature
Pacific Journal of Mathematics, 2022 In this paper, we study closed four-dimensional manifolds. In particular, we show that under various new pinching curvature conditions (for example, the sectional curvature is no more than 5/6 of the smallest Ricci eigenvalue) then the manifold is definite.
Cao, Xiaodong, Tran, Hung
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On the higher order sectional curvatures [PDF]
Illinois Journal of Mathematics, 1975 A. M. Naveira
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On the scalar curvature and sectional curvatures of a Kaehler submanifold [PDF]
Proceedings of the American Mathematical Society, 1973 For a Kaehler submanifold of a complex space form, pinching for scalar curvature implies pinching for sectional curvatures. 1 . Statement of result. The scalar curvature is, by definition, the sum of Ricci curvatures with respect to an orthonormal basis of the tangent space, and the Ricci curvature is the sum of sectional curvatures.
Koichi Ogiue, Bang-yen Chen
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Sweeping out sectional curvature [PDF]
Geometry & Topology, 2014 We observe that the maximal open set of constant curvature k in a Riemannian manifold with curvature bounded below or above by k has a convexity type property, which we call "two-convexity". This statement is used to prove a number of rigidity statements in comparison geometry.
Panov, D., Petrunin, A.
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Sectional curvature and Weitzenbock formulae
Indiana University Mathematics Journal, 2022 We establish a new algebraic characterization of sectional curvature bounds $\sec\geq k$ and $\sec\leq k$ using only curvature terms in the Weitzenböck formulae for symmetric $p$-tensors. By introducing a symmetric analogue of the Kulkarni-Nomizu product, we provide a simple formula for such curvature terms.
Bettiol, R., Mendes, R.
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Strongly positive curvature [PDF]
, 2014 We begin a systematic study of a curvature condition (strongly positive curvature) which lies strictly between positive curvature operator and positive sectional curvature, and stems from the work of Thorpe in the 1970s.
Bettiol, Renato G. +1 more
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