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  2. Natural density - Wikipedia

    en.wikipedia.org/wiki/Natural_density

    A subset A of positive integers has natural density α if the proportion of elements of A among all natural numbers from 1 to n converges to α as n tends to infinity.. More explicitly, if one defines for any natural number n the counting function a(n) as the number of elements of A less than or equal to n, then the natural density of A being α exactly means that [1]

  3. Congruence subgroup - Wikipedia

    en.wikipedia.org/wiki/Congruence_subgroup

    Here is a list of algebraic groups such that the congruence subgroup property is known to hold for the associated arithmetic lattices, in case the rank of the associated Lie group (or more generally the sum of the rank of the real and ⁠ ⁠-adic factors in the case of ⁠ ⁠-arithmetic groups) is at least 2: [14]

  4. Roth's theorem on arithmetic progressions - Wikipedia

    en.wikipedia.org/wiki/Roth's_Theorem_on...

    Roth's theorem on arithmetic progressions (infinite version): A subset of the natural numbers with positive upper density contains a 3-term arithmetic progression. An alternate, more qualitative, formulation of the theorem is concerned with the maximum size of a Salem–Spencer set which is a subset of [ N ] = { 1 , … , N } {\displaystyle [N ...

  5. List of mathematical abbreviations - Wikipedia

    en.wikipedia.org/wiki/List_of_mathematical...

    pdf – probability density function. pf – proof. PGL – projective general linear group. Pin – pin group. pmf – probability mass function. Pn – previous number. Pr – probability of an event. (See Probability theory. Also written as P or.) probit – probit function. PRNG – pseudorandom number generator.

  6. Word2vec - Wikipedia

    en.wikipedia.org/wiki/Word2vec

    These models are shallow, two-layer neural networks that are trained to reconstruct linguistic contexts of words. Word2vec takes as its input a large corpus of text and produces a vector space , typically of several hundred dimensions , with each unique word in the corpus being assigned a corresponding vector in the space.

  7. Generator (mathematics) - Wikipedia

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

    In mathematics and physics, the term generator or generating set may refer to any of a number of related concepts. The underlying concept in each case is that of a smaller set of objects, together with a set of operations that can be applied to it, that result in the creation of a larger collection of objects, called the generated set .

  8. Glossary of mathematical jargon - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_mathematical...

    A property holds "generically" on a set if the set satisfies some (context-dependent) notion of density, or perhaps if its complement satisfies some (context-dependent) notion of smallness. For example, a property which holds on a dense G δ ( intersection of countably many open sets ) is said to hold generically.

  9. Szemerédi's theorem - Wikipedia

    en.wikipedia.org/wiki/Szemerédi's_theorem

    In arithmetic combinatorics, Szemerédi's theorem is a result concerning arithmetic progressions in subsets of the integers. In 1936, Erdős and Turán conjectured [1] that every set of integers A with positive natural density contains a k-term arithmetic progression for every k. Endre Szemerédi proved the conjecture in 1975.