Results 1 to 10 of about 1,660 (35)
Deformations of nearly G2 structures
Journal of the London Mathematical Society, Volume 104, Issue 4, Page 1795-1811, November 2021., 2021 Abstract We describe the second order obstruction to deformation for nearly G2 structures on compact manifolds. Building on work of Alexandrov and Semmelmann, this allows proving rigidity under deformation for the proper nearly G2 structure on the Aloff–Wallach space N(1,1).
Paul‐Andi Nagy, Uwe Semmelmann
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Limits of Riemannian 4‐manifolds and the symplectic geometry of their twistor spaces
Transactions of the London Mathematical Society, Volume 4, Issue 1, Page 100-109, December 2017., 2017 Abstract The twistor space of a Riemannian 4‐manifold carries two almost complex structures, J+ and J−, and a natural closed 2‐form ω. This article studies limits of manifolds for which ω tames either J+ or J−. This amounts to a curvature inequality involving self‐dual Weyl curvature and Ricci curvature, and which is satisfied, for example, by all anti‐
Joel Fine
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A remark on four‐dimensional almost Kähler‐Einstein manifolds with negative scalar curvature
International Journal of Mathematics and Mathematical Sciences, Volume 2004, Issue 35, Page 1837-1842, 2004., 2004 Concerning the Goldberg conjecture, we will prove a result obtained by applying the result of Iton in terms of L2‐norm of the scalar curvature.
R. S. Lemence, T. Oguro, K. Sekigawa
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Randers manifolds of positive constant curvature
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 18, Page 1155-1165, 2003., 2003 We prove that any simply connected and complete Riemannian manifold, on which a Randers metric of positive constant flag curvature exists, must be diffeomorphic to an odd‐dimensional sphere, provided a certain 1‐form vanishes on it.
Aurel Bejancu, Hani Reda Farran
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A note on Chen′s basic equality for submanifolds in a Sasakian space form
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 11, Page 711-716, 2003., 2003 It is proved that a Riemannian manifold M isometrically immersed in a Sasakian space form M˜(c) of constant φ‐sectional curvature c < 1, with the structure vector field ξ tangent to M, satisfies Chen′s basic equality if and only if it is a 3‐dimensional minimal invariant submanifold.
Mukut Mani Tripathi +2 more
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Some submersions of CR‐hypersurfaces of Kaehler‐Einstein manifold
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 18, Page 1137-1144, 2003., 2003 The Riemannian submersions of a CR‐hypersurface M of a Kaehler‐Einstein manifold M˜ are studied. If M is an extrinsic CR‐hypersurface of M˜, then it is shown that the base space of the submersion is also a Kaehler‐Einstein manifold.
Vittorio Mangione
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Foliations by minimal surfaces and contact structures on certain closed 3‐manifolds
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 21, Page 1323-1330, 2003., 2003 Let (M, g) be a closed, connected, oriented C∞ Riemannian 3‐manifold with tangentially oriented flow F. Suppose that F admits a basic transverse volume form μ and mean curvature one‐form κ which is horizontally closed. Let {X, Y} be any pair of basic vector fields, so μ(X, Y) = 1.
Richard H. Escobales Jr.
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The local moduli of Sasakian 3‐manifolds
International Journal of Mathematics and Mathematical Sciences, Volume 32, Issue 2, Page 117-127, 2002., 2002 The Newman‐Penrose‐Perjes formalism is applied to Sasakian 3‐manifolds and the local form of the metric and contact structure is presented. The local moduli space can be parameterised by a single function of two variables and it is shown that, given any smooth function of two variables, there exists locally a Sasakian structure with scalar curvature ...
Brendan S. Guilfoyle
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Ricci curvature of submanifolds in Kenmotsu space forms
International Journal of Mathematics and Mathematical Sciences, Volume 29, Issue 12, Page 719-726, 2002., 2002 In 1999, Chen established a sharp relationship between the Ricci curvature and the squared mean curvature for a submanifold in a Riemannian space form with arbitrary codimension. Similar problems for submanifolds in complex space forms were studied by Matsumoto et al.
Kadri Arslan +4 more
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Chern classes of integral submanifolds of some contact manifolds
International Journal of Mathematics and Mathematical Sciences, Volume 32, Issue 8, Page 481-490, 2002., 2002 A complex subbundle of the normal bundle to an integral submanifold of the contact distribution in a Sasakian manifold is given. The geometry of this bundle is investigated and some results concerning its Chern classes are obtained.
Gheorghe Pitiş
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