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  2. Tuple - Wikipedia

    en.wikipedia.org/wiki/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 and an ordered pair, respectively. The term "infinite tuple" is occasionally used for "infinite sequences".

  3. List (abstract data type) - Wikipedia

    en.wikipedia.org/wiki/List_(abstract_data_type)

    List (abstract data type) In computer science, a list or sequence is collection of items that are finite in number and in a particular order. An instance of a list is a computer representation of the mathematical concept of a tuple or finite sequence. A list may contain the same value more than once, and each occurrence is considered a distinct ...

  4. Cartesian product - Wikipedia

    en.wikipedia.org/wiki/Cartesian_product

    In mathematics, specifically set theory, the Cartesian product of two sets A and B, denoted A × B, is the set of all ordered pairs (a, b) where a is in A and b is in B. [1] In terms of set-builder notation, that is [2][3] A table can be created by taking the Cartesian product of a set of rows and a set of columns.

  5. Multiset - Wikipedia

    en.wikipedia.org/wiki/Multiset

    A multiset may be formally defined as an ordered pair (A, m) where A is the underlying set of the multiset, formed from its distinct elements, and : + is a function from A to the set of positive integers, giving the multiplicity – that is, the number of occurrences – of the element a in the multiset as the number m(a).

  6. Permutation - Wikipedia

    en.wikipedia.org/wiki/Permutation

    In mathematics, a permutation of a set can mean one of two different things: an arrangement of its members in a sequence or linear order, or. the act or process of changing the linear order of an ordered set. [ 1 ] An example of the first meaning is the six permutations (orderings) of the set {1, 2, 3}: written as tuples, they are (1, 2, 3), (1 ...

  7. Name–value pair - Wikipedia

    en.wikipedia.org/wiki/Name–value_pair

    A name–value pair, also called an attribute–value pair, key–value pair, or field–value pair, is a fundamental data representation in computing systems and applications. Designers often desire an open-ended data structure that allows for future extension without modifying existing code or data. In such situations, all or part of the data ...

  8. Binary relation - Wikipedia

    en.wikipedia.org/wiki/Binary_relation

    In order to specify the choices of the sets and , some authors define a binary relation or correspondence as an ordered triple (,,), where is a subset of called the graph of the binary relation. The statement ( x , y ) ∈ R {\displaystyle (x,y)\in R} reads " x {\displaystyle x} is R {\displaystyle R} -related to y {\displaystyle y} " and is ...

  9. Relational algebra - Wikipedia

    en.wikipedia.org/wiki/Relational_algebra

    In database theory, relational algebra is a theory that uses algebraic structures for modeling data and defining queries on it with well founded semantics. The theory was introduced by Edgar F. Codd. The main application of relational algebra is to provide a theoretical foundation for relational databases, particularly query languages for such ...