Curvature (mathematics) | Riemannian geometry | Riemannian manifolds

Sectional curvature

In Riemannian geometry, the sectional curvature is one of the ways to describe the curvature of Riemannian manifolds. The sectional curvature K(σp) depends on a two-dimensional linear subspace σp of the tangent space at a point p of the manifold. It can be defined geometrically as the Gaussian curvature of the surface which has the plane σp as a tangent plane at p, obtained from geodesics which start at p in the directions of σp (in other words, the image of σp under the exponential map at p). The sectional curvature is a real-valued function on the 2-Grassmannian bundle over the manifold. The sectional curvature determines the curvature tensor completely. (Wikipedia).

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From playlist Life Science Math: Vectors

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From playlist Vector Valued Functions

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From playlist Ecole d'été 2021 - Curvature Constraints and Spaces of Metrics

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Hopf conjecture | Aspherical space | Space form | Schur's lemma (Riemannian geometry) | Soul theorem | Fiber bundle | Tangent space | Élie Cartan | Isoperimetric inequality | Cartan–Hadamard theorem | Grassmannian | Hyperbolic geometry | Cartan–Hadamard conjecture | Riemann curvature tensor | Riemannian geometry | Exponential map (Riemannian geometry) | Hyperbolic space | Curvature of Riemannian manifolds | Toponogov's theorem | Hadamard manifold | Geodesic | Riemannian manifold | Comparison theorem | Isometry | Euclidean space | N-sphere | Glossary of Riemannian and metric geometry | Fundamental group | Curvature | Gaussian curvature | Surface (topology)