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  2. Differential geometry of surfaces - Wikipedia

    en.wikipedia.org/wiki/Differential_geometry_of...

    The idea of local parametrization and change of coordinate was later formalized through the current abstract notion of a manifold, a topological space where the smooth structure is given by local charts on the manifold, exactly as the planet Earth is mapped by atlases today. Changes of coordinates between different charts of the same region are ...

  3. Hypersurface - Wikipedia

    en.wikipedia.org/wiki/Hypersurface

    In geometry, a hypersurface is a generalization of the concepts of hyperplane, plane curve, and surface.A hypersurface is a manifold or an algebraic variety of dimension n − 1, which is embedded in an ambient space of dimension n, generally a Euclidean space, an affine space or a projective space. [1]

  4. Exotic R4 - Wikipedia

    en.wikipedia.org/wiki/Exotic_R4

    In mathematics, an exotic is a differentiable manifold that is homeomorphic (i.e. shape preserving) but not diffeomorphic (i.e. non smooth) to the Euclidean space. The first examples were found in 1982 by Michael Freedman and others, by using the contrast between Freedman's theorems about topological 4-manifolds, and Simon Donaldson's theorems about smooth 4-manifolds.

  5. Topological manifold - Wikipedia

    en.wikipedia.org/wiki/Topological_manifold

    A topological space X is called locally Euclidean if there is a non-negative integer n such that every point in X has a neighborhood which is homeomorphic to real n-space R n. [2] A topological manifold is a locally Euclidean Hausdorff space. It is common to place additional requirements on topological manifolds.

  6. 3-sphere - Wikipedia

    en.wikipedia.org/wiki/3-sphere

    The 3-sphere is naturally a smooth manifold, in fact, a closed embedded submanifold of R 4. The Euclidean metric on R 4 induces a metric on the 3-sphere giving it the structure of a Riemannian manifold. As with all spheres, the 3-sphere has constant positive sectional curvature equal to ⁠ 1 / r 2 ⁠ where r is the radius.

  7. Atlas (topology) - Wikipedia

    en.wikipedia.org/wiki/Atlas_(topology)

    In mathematics, particularly topology, an atlas is a concept used to describe a manifold. An atlas consists of individual charts that, roughly speaking, describe individual regions of the manifold. In general, the notion of atlas underlies the formal definition of a manifold and related structures such as vector bundles and other fiber bundles.

  8. Category of manifolds - Wikipedia

    en.wikipedia.org/wiki/Category_of_manifolds

    The objects of Man • p are pairs (,), where is a manifold along with a basepoint , and its morphisms are basepoint-preserving p-times continuously differentiable maps: e.g. : (,) (,), such that () =. [1] The category of pointed manifolds is an example of a comma category - Man • p is exactly ({}), where {} represents an arbitrary singleton ...

  9. Mean curvature flow - Wikipedia

    en.wikipedia.org/wiki/Mean_curvature_flow

    In the field of differential geometry in mathematics, mean curvature flow is an example of a geometric flow of hypersurfaces in a Riemannian manifold (for example, smooth surfaces in 3-dimensional Euclidean space).