In algebra

• Order (group theory)
  Order (group theory)
  In group theory, a branch of mathematics, the term order is used in two closely related senses:* The order of a group is its cardinality, i.e., the number of its elements....
  
  , the cardinality of a group or period of an element
• Order, or degree of a polynomial
  Degree of a polynomial
  The degree of a polynomial represents the highest degree of a polynominal's terms , should the polynomial be expressed in canonical form . The degree of an individual term is the sum of the exponents acting on the term's variables...
  
  
• Order, or dimension of a matrix
• Order (ring theory), an algebraic structure
• Ordered group
  Ordered group
  In abstract algebra, a partially-ordered group is a group equipped with a partial order "≤" that is translation-invariant; in other words, "≤" has the property that, for all a, b, and g in G, if a ≤ b then a+g ≤ b+g and g+a ≤ g+b.An element x of G is called positive element if 0 ≤ x...
  
  
• Ordered field
  Ordered field
  In mathematics, an ordered field is a field together with a total ordering of its elements that is compatible with the field operations. Historically, the axiomatization of an ordered field was abstracted gradually from the real numbers, by mathematicians including David Hilbert, Otto Hölder and...
  
  

In arithmetic

• Order (number theory), the multiplicative order
  Multiplicative order
  In number theory, given an integer a and a positive integer n with gcd = 1, the multiplicative order of a modulo n is the smallest positive integer k withThe order of a modulo n is usually written ordn, or On.- Example :To determine the multiplicative order of 4 modulo 7, we compute 42 = 16 ≡ 2 ...
  
   in modular arithmetic
• Orders of magnitude, a class of scale or magnitude of any amount
• Order of operations
  Order of operations
  In mathematics and computer programming, the order of operations is a rule used to clarify unambiguously which procedures should be performed first in a given mathematical expression....
  
  

In analysis

• Orders of approximation
  Orders of approximation
  In science, engineering, and other quantitative disciplines, orders of approximation refer to formal or informal terms for how precise an approximation is, and to indicate progressively more refined approximations: in increasing order of precision, a zeroth order approximation, a first order...
  
   in Big O notation
• Order of convergence, a measurement of convergence
• Order (differential equation), or order of highest derivative, of a differential equation
• Order of an entire function
  Entire function
  In complex analysis, an entire function, also called an integral function, is a complex-valued function that is holomorphic over the whole complex plane...
  
  
• Ordered list, a tuple
  Tuple
  In mathematics and computer science, a tuple is an ordered list of elements. In set theory, an n-tuple is a sequence of n elements, where n is a positive integer. There is also one 0-tuple, an empty sequence. An n-tuple is defined inductively using the construction of an ordered pair...
  
   or sequence
  Sequence
  In mathematics, a sequence is an ordered list of objects . Like a set, it contains members , and the number of terms is called the length of the sequence. Unlike a set, order matters, and exactly the same elements can appear multiple times at different positions in the sequence...
  
  
• Z-order (curve)
  Z-order (curve)
  In mathematical analysis and computer science, Z-order, Morton order, or Morton code is a space-filling curve which maps multidimensional data to one dimension while preserving locality of the data points. It was introduced in 1966 by G. M. Morton...
  
  , a space-filling curve
• NURBS order, a number one greater than the degree of the polynomial representation of a non-uniform rational B-spline

In combinatorics

• Order in the Josephus permutation
• Weak order of permutations
• Ordered selections and partitions of the twelvefold way in combinatorics
• Ordered set, a permutation
  Permutation
  In mathematics, the notion of permutation is used with several slightly different meanings, all related to the act of permuting objects or values. Informally, a permutation of a set of objects is an arrangement of those objects into a particular order...
  
  , bijection
  Bijection
  A bijection is a function giving an exact pairing of the elements of two sets. A bijection from the set X to the set Y has an inverse function from Y to X. If X and Y are finite sets, then the existence of a bijection means they have the same number of elements...
  
   or cyclic order
• Unordered subset
  Subset
  In mathematics, especially in set theory, a set A is a subset of a set B if A is "contained" inside B. A and B may coincide. The relationship of one set being a subset of another is called inclusion or sometimes containment...
  
   or combination

In statistics

• Mean
  Mean
  In statistics, mean has two related meanings:* the arithmetic mean .* the expected value of a random variable, which is also called the population mean....
  
  , median
  Median
  In probability theory and statistics, a median is described as the numerical value separating the higher half of a sample, a population, or a probability distribution, from the lower half. The median of a finite list of numbers can be found by arranging all the observations from lowest value to...
  
  , quantiles are first-order statistics
• Variance
  Variance
  In probability theory and statistics, the variance is a measure of how far a set of numbers is spread out. It is one of several descriptors of a probability distribution, describing how far the numbers lie from the mean . In particular, the variance is one of the moments of a distribution...
  
  , correlation
  Correlation
  In statistics, dependence refers to any statistical relationship between two random variables or two sets of data. Correlation refers to any of a broad class of statistical relationships involving dependence....
  
  , power spectrum are second-order statistics
• Skewness
  Skewness
  In probability theory and statistics, skewness is a measure of the asymmetry of the probability distribution of a real-valued random variable. The skewness value can be positive or negative, or even undefined...
  
  , bispectrum
  Bispectrum
  In mathematics, in the area of statistical analysis, the bispectrum is a statistic used to search for nonlinear interactions. The Fourier transform of the second-order cumulant, i.e., the autocorrelation function, is the traditional power spectrum...
  
  , kurtosis
  Kurtosis
  In probability theory and statistics, kurtosis is any measure of the "peakedness" of the probability distribution of a real-valued random variable...
  
   are examples of higher-order statistics
  Higher-order statistics
  Higher-order statistics are descriptive measures of, among other things, qualities of probability distributions and sample distributions, and are, themselves, extensions of first- and second-order measures to higher orders. Skewness and kurtosis are examples of this...
  
  

In fractals

• Complexor
  Complexor
  In chaos theory a complexor is mathematically equivalent to a chaotic attractor. The word was coined by Marcial Losada , derived from the words "complex order"....
  
  , or complex order in fractals
• Orders of construction in the Pythagoras tree
• Order of extension in Lakes of Wada
  Lakes of Wada
  In mathematics, the lakes of Wada are three disjoint connected open sets of the plane with the counterintuitive property that they all have the same boundary....
  
  
• Order of Rényi dimensions
  Fractal dimension
  In fractal geometry, the fractal dimension, D, is a statistical quantity that gives an indication of how completely a fractal appears to fill space, as one zooms down to finer and finer scales. There are many specific definitions of fractal dimension. The most important theoretical fractal...
  
  

In graphs

• Graph order, the number of nodes in a graph
• Ordered pair
  Ordered pair
  In mathematics, an ordered pair is a pair of mathematical objects. In the ordered pair , the object a is called the first entry, and the object b the second entry of the pair...
  
  , including undirected and directed graphs
• Ordered triple
  Tuple
  In mathematics and computer science, a tuple is an ordered list of elements. In set theory, an n-tuple is a sequence of n elements, where n is a positive integer. There is also one 0-tuple, an empty sequence. An n-tuple is defined inductively using the construction of an ordered pair...
  
  , or mixed graph
  • Glossary of graph theory
    Glossary of graph theory
    Graph theory is a growing area in mathematical research, and has a large specialized vocabulary. Some authors use the same word with different meanings. Some authors use different words to mean the same thing. This page attempts to keep up with current usage....
    
    

Order theory

• Order theory
  Order theory
  Order theory is a branch of mathematics which investigates our intuitive notion of order using binary relations. It provides a formal framework for describing statements such as "this is less than that" or "this precedes that". This article introduces the field and gives some basic definitions...
  
  , which studies various binary relations known as orders
• Order (journal)
  Order (journal)
  Order is a quarterly peer-reviewed academic journal on order theory and its applications, published by Springer Science+Business Media. It was founded in 1984 by University of Calgary mathematics professor Ivan Rival; as of 2010, its editor in chief is Dwight Duffus, the Goodrich C...
  
  , an academic journal on order theory
• Partial order, often called just "order" in order theory texts; a transitive antisymmetric relation
• Total order
  Total order
  In set theory, a total order, linear order, simple order, or ordering is a binary relation on some set X. The relation is transitive, antisymmetric, and total...
  
  , a partial order that is also total, in that either the relation or its inverse holds between any unequal elements
• Dense order
  Dense order
  In mathematics, a partial order ≤ on a set X is said to be dense if, for all x and y in X for which x In mathematics, a partial order ≤ on a set X is said to be dense if, for all x and y in X for which x...
  
  , a total order where between any unequal pair of elements there is always an intervening element in the order
• Order topology
  Order topology
  In mathematics, an order topology is a certain topology that can be defined on any totally ordered set. It is a natural generalization of the topology of the real numbers to arbitrary totally ordered sets...
  
  , a topology of total order for totally ordered sets
• Ordinal numbers, which are assigned to sets based on their set-theoretic order
• Glossary of order theory
  Glossary of order theory
  This is a glossary of some terms used in various branches of mathematics that are related to the fields of order, lattice, and domain theory. Note that there is a structured list of order topics available as well...
  
  
• List of order theory topics

In other mathematical theories

• Order in Ramsey theory
  Ramsey theory
  Ramsey theory, named after the British mathematician and philosopher Frank P. Ramsey, is a branch of mathematics that studies the conditions under which order must appear...
  
  , uniform structures in consequence to critical set cardinality
• Set theory (music)
  Set theory (music)
  Musical set theory provides concepts for categorizing musical objects and describing their relationships. Many of the notions were first elaborated by Howard Hanson in connection with tonal music, and then mostly developed in connection with atonal music by theorists such as Allen Forte , drawing...
  
   encompasses ordered pitch and pitch classes (Musical set theory)
• Type theory
  Type theory
  In mathematics, logic and computer science, type theory is any of several formal systems that can serve as alternatives to naive set theory, or the study of such formalisms in general...
  
   encompasses: zeroth-order
  Zeroth-order logic
  Zeroth-order logic is first-order logic without quantifiers. A finitely axiomatizable zeroth-order logic is isomorphic to a propositional logic. Zeroth-order logic with axiom schema is a more expressive system than propositional logic...
  
  , first-order
  First-order logic
  First-order logic is a formal logical system used in mathematics, philosophy, linguistics, and computer science. It goes by many names, including: first-order predicate calculus, the lower predicate calculus, quantification theory, and predicate logic...
  
  , second-order
  Second-order logic
  In logic and mathematics second-order logic is an extension of first-order logic, which itself is an extension of propositional logic. Second-order logic is in turn extended by higher-order logic and type theory....
  
   and higher-order logic
  Higher-order logic
  In mathematics and logic, a higher-order logic is a form of predicate logic that is distinguished from first-order logic by additional quantifiers and a stronger semantics...