# Flag curvature

## Definition

The **flag curvature** of a Finsler manifold (viz a differential manifold endowed with a Finsler metric ) defines a scalar (real number) for the following input: a point on the manifold, a tangent plane at that point, and a nonzero vector in the tangent plane.

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When the Finsler metricis a Riemannian metric, the flag curvature depends only on the tangent plane and *not* on the nonzero vector. Further, it equals the sectional curvature of that tangent plane.