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  2. 3-sphere - Wikipedia

    en.wikipedia.org/wiki/3-sphere

    Direct projection of 3-sphere into 3D space and covered with surface grid, showing structure as stack of 3D spheres (2-spheres) In mathematics, a hypersphere or 3-sphere is a 4-dimensional analogue of a sphere, and is the 3-dimensional n-sphere. In 4-dimensional Euclidean space, it is the set of points equidistant from a fixed central point.

  3. Homotopy groups of spheres - Wikipedia

    en.wikipedia.org/wiki/Homotopy_groups_of_spheres

    An ordinary sphere in three-dimensional space—the surface, not the solid ball—is just one example of what a sphere means in topology. Geometry defines a sphere rigidly, as a shape. Here are some alternatives. Implicit surface: x 2 0 + x 2 1 + x 2 2 = 1; This is the set of points in 3-dimensional Euclidean space found

  4. Dymaxion map - Wikipedia

    en.wikipedia.org/wiki/Dymaxion_map

    The March 1, 1943, edition of Life magazine included a photographic essay titled "Life Presents R. Buckminster Fuller's Dymaxion World", illustrating a projection onto a cuboctahedron, including several examples of possible arrangements of the square and triangular pieces, and a pull-out section of one-sided magazine pages with the map faces printed on them, intended to be cut out and glued to ...

  5. n-sphere - Wikipedia

    en.wikipedia.org/wiki/N-sphere

    In mathematics, an n-sphere or hypersphere is an ⁠ ⁠-dimensional generalization of the ⁠ ⁠-dimensional circle and ⁠ ⁠-dimensional sphere to any non-negative integer ⁠ ⁠. The circle is considered 1-dimensional, and the sphere 2-dimensional, because the surfaces themselves are 1- and 2-dimensional respectively, not because they ...

  6. 3-manifold - Wikipedia

    en.wikipedia.org/wiki/3-manifold

    The 3-sphere is an especially important 3-manifold because of the now-proven Poincaré conjecture. Originally conjectured by Henri Poincaré, the theorem concerns a space that locally looks like ordinary three-dimensional space but is connected, finite in size, and lacks any boundary (a closed 3-manifold).

  7. Sphere - Wikipedia

    en.wikipedia.org/wiki/Sphere

    A sphere (from Greek σφαῖρα, sphaîra) [1] is a geometrical object that is a three-dimensional analogue to a two-dimensional circle. Formally, a sphere is the set of points that are all at the same distance r from a given point in three-dimensional space. [2] That given point is the center of the sphere, and r is the sphere's radius.

  8. Hopf fibration - Wikipedia

    en.wikipedia.org/wiki/Hopf_fibration

    Furthermore, if two points on the 3-sphere map to the same point on the 2-sphere, i.e., if p(z 0, z 1) = p(w 0, w 1), then (w 0, w 1) must equal (λ z 0, λ z 1) for some complex number λ with |λ| 2 = 1. The converse is also true; any two points on the 3-sphere that differ by a common complex factor λ map to the same point on the 2-sphere.

  9. Surface (topology) - Wikipedia

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

    In the part of mathematics referred to as topology, a surface is a two-dimensional manifold. Some surfaces arise as the boundaries of three-dimensional solid figures; for example, the sphere is the boundary of the solid ball. Other surfaces arise as graphs of functions of two variables; see the figure at right.