In mathematics, the flatness (symbol: ⏥) of a surface is the degree to which it approximates a mathematical plane. The term is often generalized for higher-dimensional manifolds to describe the degree to which they approximate the Euclidean space of the same dimensionality. (See curvature.)
Flatness in homological algebra and algebraic geometry means, of an object
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Flatness (mathematics) Wikipedia(Text) CC BY-SA