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  2. Tuple - Wikipedia

    en.wikipedia.org/wiki/Tuple

    Tuple. In mathematics, a tuple is a finite sequence or ordered list of numbers or, more generally, mathematical objects, which are called the elements of the tuple. An n-tuple is a tuple of n elements, where n is a non-negative integer. There is only one 0-tuple, called the empty tuple. A 1-tuple and a 2-tuple are commonly called a singleton ...

  3. Relational algebra - Wikipedia

    en.wikipedia.org/wiki/Relational_algebra

    That is, the Cartesian product of a set of n-tuples with a set of m-tuples yields a set of "flattened" (n + m)-tuples (whereas basic set theory would have prescribed a set of 2-tuples, each containing an n-tuple and an m-tuple). More formally, R × S is defined as follows:

  4. Multiset - Wikipedia

    en.wikipedia.org/wiki/Multiset

    In mathematics, a multiset (or bag, or mset) is a modification of the concept of a set that, unlike a set, [1] allows for multiple instances for each of its elements. The number of instances given for each element is called the multiplicity of that element in the multiset. As a consequence, an infinite number of multisets exist that contain ...

  5. Relational model - Wikipedia

    en.wikipedia.org/wiki/Relational_model

    The relational model (RM) is an approach to managing data using a structure and language consistent with first-order predicate logic, first described in 1969 by English computer scientist Edgar F. Codd, [1][2] where all data is represented in terms of tuples, grouped into relations. A database organized in terms of the relational model is a ...

  6. Permutation - Wikipedia

    en.wikipedia.org/wiki/Permutation

    To effectively convert a Lehmer code d n, d n−1, ..., d 2, d 1 into a permutation of an ordered set S, one can start with a list of the elements of S in increasing order, and for i increasing from 1 to n set σ i to the element in the list that is preceded by d n+1−i other ones, and remove that element from the list.

  7. Function (mathematics) - Wikipedia

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

    In mathematics, a function from a set X to a set Y assigns to each element of X exactly one element of Y. [ 1 ] The set X is called the domain of the function [ 2 ] and the set Y is called the codomain of the function. [ 3 ] Functions were originally the idealization of how a varying quantity depends on another quantity.

  8. Real coordinate space - Wikipedia

    en.wikipedia.org/wiki/Real_coordinate_space

    In mathematics, the real coordinate space or real coordinate n-space, of dimension n, denoted Rn or , is the set of all ordered n -tuples of real numbers, that is the set of all sequences of n real numbers, also known as coordinate vectors. Special cases are called the real line R1, the real coordinate planeR2, and the real coordinate three ...

  9. Direct sum - Wikipedia

    en.wikipedia.org/wiki/Direct_sum

    The direct sum is an operation between structures in abstract algebra, a branch of mathematics. It is defined differently, but analogously, for different kinds of structures. As an example, the direct sum of two abelian groups and is another abelian group consisting of the ordered pairs where and . To add ordered pairs, we define the sum to be ...