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  2. Projective plane - Wikipedia

    en.wikipedia.org/wiki/Projective_plane

    A projective plane of order N is a Steiner S(2, N + 1, N 2 + N + 1) system (see Steiner system). Conversely, one can prove that all Steiner systems of this form (λ = 2) are projective planes. The number of mutually orthogonal Latin squares of order N is at most N − 1. N − 1 exist if and only if there is a projective plane of order N.

  3. Bruck–Ryser–Chowla theorem - Wikipedia

    en.wikipedia.org/wiki/Bruck–Ryser–Chowla_theorem

    The theorem, for example, rules out the existence of projective planes of orders 6 and 14 but allows the existence of planes of orders 10 and 12. Since a projective plane of order 10 has been shown not to exist using a combination of coding theory and large-scale computer search, [1] the condition of the theorem is evidently not sufficient for ...

  4. Galois geometry - Wikipedia

    en.wikipedia.org/wiki/Galois_geometry

    The Fano plane, the projective plane over the field with two elements, is one of the simplest objects in Galois geometry.. Galois geometry (named after the 19th-century French mathematician Évariste Galois) is the branch of finite geometry that is concerned with algebraic and analytic geometry over a finite field (or Galois field). [1]

  5. Fano plane - Wikipedia

    en.wikipedia.org/wiki/Fano_plane

    According to a theorem by Steinitz [12] configurations of this type can be realized in the Euclidean plane having at most one curved line (all other lines lying on Euclidean lines). [13] The upper figure is an alternative representation of the Fano plane in grid layout – compare with one of the finite projective plane of order 3 below

  6. Projective geometry - Wikipedia

    en.wikipedia.org/wiki/Projective_geometry

    Projective geometry was instrumental in the validation of speculations of Lobachevski and Bolyai concerning hyperbolic geometry by providing models for the hyperbolic plane: [12] for example, the Poincaré disc model where generalised circles perpendicular to the unit circle correspond to "hyperbolic lines" , and the "translations" of this ...

  7. Incidence geometry - Wikipedia

    en.wikipedia.org/wiki/Incidence_geometry

    If P is a finite set, the projective plane is referred to as a finite projective plane. The order of a finite projective plane is n = k – 1, that is, one less than the number of points on a line. All known projective planes have orders that are prime powers. A projective plane of order n is an ((n 2 + n + 1) n + 1) configuration. The smallest ...

  8. Real projective plane - Wikipedia

    en.wikipedia.org/wiki/Real_projective_plane

    The quotient map from the sphere onto the real projective plane is in fact a two sheeted (i.e. two-to-one) covering map. It follows that the fundamental group of the real projective plane is the cyclic group of order 2; i.e., integers modulo 2.

  9. Non-Desarguesian plane - Wikipedia

    en.wikipedia.org/wiki/Non-Desarguesian_plane

    Hanfried Lenz gave a classification scheme for projective planes in 1954, [6] which was refined by Adriano Barlotti in 1957. [7] This classification scheme is based on the types of point–line transitivity permitted by the collineation group of the plane and is known as the Lenz–Barlotti classification of projective planes.