# Disjoint

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**Ideal (order theory)**— In mathematical order theory, an ideal is a special subset of a partially ordered set (poset). Although this term historically was derived from the notion of a ring ideal of abstract algebra, it has subsequently been generalized to a different… …82

**Non-measurable set**— This page gives a general overview of the concept of non measurable sets. For a precise definition of measure, see Measure (mathematics). For various constructions of non measurable sets, see Vitali set, Hausdorff paradox, and Banach–Tarski… …83

**Symbolic combinatorics**— in mathematics is a technique of analytic combinatorics that uses symbolic representations of combinatorial classes to derive their generating functions. The underlying mathematics, including the Pólya enumeration theorem, are explained on the… …84

**Sigma additivity**— In mathematics, additivity and sigma additivity of a function defined on subsets of a given set are abstractions of the intuitive properties of size (length, area, volume) of a set. Contents 1 Additive (or finitely additive) set functions 2 σ… …85

**Point process**— In statistics and probability theory, a point process is a type of random process for which any one realisation consists of a set of isolated points either in time or geographical space, or in even more general spaces. For example, the occurrence …86

**Graph operations**— Operations on graphs produce new graphs from old ones. They may be separated into the following major categories. Contents 1 Unary operations 1.1 Elementary operations 1.2 Advanced operations 2 …87

**Polynomial conjoint measurement**— is an extension of the theory of conjoint measurement to three or more attributes. It was initially developed by the mathematical psychologists David Krantz (1968) and Amos Tversky (1967). The theory was given a comprehensive mathematical… …88

**Théorème de Robertson-Seymour**— En mathématiques, et plus précisément en théorie des graphes, le théorème de Robertson–Seymour (parfois également appelé le théorème des mineurs, et connu, avant qu il soit démontré, sous le nom de conjecture de Wagner), est un théorème démontré… …89

**Axiom of choice**— This article is about the mathematical concept. For the band named after it, see Axiom of Choice (band). In mathematics, the axiom of choice, or AC, is an axiom of set theory stating that for every family of nonempty sets there exists a family of …90

**Axiom of regularity**— In mathematics, the axiom of regularity (also known as the axiom of foundation) is one of the axioms of Zermelo Fraenkel set theory and was introduced by harvtxt|von Neumann|1925. In first order logic the axiom reads::forall A (exists B (B in A)… …