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  2. Intersection number - Wikipedia

    en.wikipedia.org/wiki/Intersection_number

    There is an approach to intersection number, introduced by Snapper in 1959-60 and developed later by Cartier and Kleiman, that defines an intersection number as an Euler characteristic. Let X be a scheme over a scheme S , Pic( X ) the Picard group of X and G the Grothendieck group of the category of coherent sheaves on X whose support is proper ...

  3. Intersection number (graph theory) - Wikipedia

    en.wikipedia.org/wiki/Intersection_number_(graph...

    As well as being called the intersection number, the minimum number of these cliques has been called the R-content, [7] edge clique cover number, [4] or clique cover number. [8] The problem of computing the intersection number has been called the intersection number problem , [ 9 ] the intersection graph basis problem , [ 10 ] covering by ...

  4. Intersection - Wikipedia

    en.wikipedia.org/wiki/Intersection

    As another example, the number 5 is not contained in the intersection of the set of prime numbers {2, 3, 5, 7, 11, …} and the set of even numbers {2, 4, 6, 8, 10, …} , because although 5 is a prime number, it is not even. In fact, the number 2 is the only number in the intersection of these two

  5. Serre's multiplicity conjectures - Wikipedia

    en.wikipedia.org/wiki/Serre's_multiplicity...

    Since André Weil's initial definition of intersection numbers, around 1949, there had been a question of how to provide a more flexible and computable theory, which Serre sought to address. In 1958, Serre realized that classical algebraic-geometric ideas of multiplicity could be generalized using the concepts of homological algebra .

  6. Riemann–Roch theorem for surfaces - Wikipedia

    en.wikipedia.org/wiki/Riemann–Roch_theorem_for...

    K) is a Chern number and the self-intersection number of the canonical class K, and e = c 2 is the topological Euler characteristic. It can be used to replace the term χ(0) in the Riemann–Roch theorem with topological terms; this gives the Hirzebruch–Riemann–Roch theorem for surfaces.

  7. Distance-regular graph - Wikipedia

    en.wikipedia.org/wiki/Distance-regular_graph

    The numbers ,, are called the intersection numbers of the graph. They satisfy the equation + + =, where = is the valency, i.e., the number of ...

  8. Enumerative geometry - Wikipedia

    en.wikipedia.org/wiki/Enumerative_geometry

    2 The number of lines meeting 4 general lines in space; 8 The number of circles tangent to 3 general circles (the problem of Apollonius). 27 The number of lines on a smooth cubic surface (Salmon and Cayley) 2875 The number of lines on a general quintic threefold; 3264 The number of conics tangent to 5 plane conics in general position

  9. Set (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Set_(mathematics)

    A set of polygons in an Euler diagram This set equals the one depicted above since both have the very same elements.. In mathematics, a set is a collection of different [1] things; [2] [3] [4] these things are called elements or members of the set and are typically mathematical objects of any kind: numbers, symbols, points in space, lines, other geometrical shapes, variables, or even other ...