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  2. Ramanujan's ternary quadratic form - Wikipedia

    en.wikipedia.org/wiki/Ramanujan's_ternary...

    In number theory, a branch of mathematics, Ramanujan's ternary quadratic form is the algebraic expression x 2 + y 2 + 10z 2 with integral values for x, y and z. [ 1 ] [ 2 ] Srinivasa Ramanujan considered this expression in a footnote in a paper [ 3 ] published in 1916 and briefly discussed the representability of integers in this form.

  3. Quadratic form - Wikipedia

    en.wikipedia.org/wiki/Quadratic_form

    An integral quadratic form has integer coefficients, such as x 2 + xy + y 2; equivalently, given a lattice Λ in a vector space V (over a field with characteristic 0, such as Q or R), a quadratic form Q is integral with respect to Λ if and only if it is integer-valued on Λ, meaning Q(x, y) ∈ Z if x, y ∈ Λ.

  4. Category:Quadratic forms - Wikipedia

    en.wikipedia.org/wiki/Category:Quadratic_forms

    Ramanujan's ternary quadratic form; S. ... Quadratic form (statistics) Surgery structure set; Sylvester's law of inertia; T. Tensor product of quadratic forms; U. U ...

  5. Genus of a quadratic form - Wikipedia

    en.wikipedia.org/wiki/Genus_of_a_quadratic_form

    An integral quadratic form is a quadratic form on Z n, or equivalently a free Z-module of finite rank. Two such forms are in the same genus if they are equivalent over the local rings Z p for each prime p and also equivalent over R .

  6. Glossary of biology - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_biology

    This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms.It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology ...

  7. Binary quadratic form - Wikipedia

    en.wikipedia.org/wiki/Binary_quadratic_form

    The oldest problem in the theory of binary quadratic forms is the representation problem: describe the representations of a given number by a given quadratic form f. "Describe" can mean various things: give an algorithm to generate all representations, a closed formula for the number of representations, or even just determine whether any ...

  8. Definite quadratic form - Wikipedia

    en.wikipedia.org/wiki/Definite_quadratic_form

    In mathematics, a definite quadratic form is a quadratic form over some real vector space V that has the same sign (always positive or always negative) for every non-zero vector of V. According to that sign, the quadratic form is called positive-definite or negative-definite .

  9. Quadric - Wikipedia

    en.wikipedia.org/wiki/Quadric

    In mathematics, a quadric or quadric surface (quadric hypersurface in higher dimensions), is a generalization of conic sections (ellipses, parabolas, and hyperbolas).It is a hypersurface (of dimension D) in a (D + 1)-dimensional space, and it is defined as the zero set of an irreducible polynomial of degree two in D + 1 variables; for example, D = 1 in the case of conic sections.