uncountable set
21Borel set — In mathematics, a Borel set is any set in a topological space that can be formed from open sets (or, equivalently, from closed sets) through the operations of countable union, countable intersection, and relative complement. Borel sets are named… …
22Cantor set — In mathematics, the Cantor set, introduced by German mathematician Georg Cantor in 1883 [Georg Cantor (1883) Über unendliche, lineare Punktmannigfaltigkeiten V [On infinite, linear point manifolds (sets)] , Mathematische Annalen , vol. 21, pages… …
23Paradoxes of set theory — This article contains a discussion of paradoxes of set theory. As with most mathematical paradoxes, they generally reveal surprising and counter intuitive mathematical results, rather than actual logical contradictions within modern axiomatic set …
24Non-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… …
25Club set — In mathematics, particularly in mathematical logic and set theory, a club set is a subset of a limit ordinal which is closed under the order topology, and is unbounded relative to the limit ordinal. The name club is a contraction of closed and… …
26Stationary set — In mathematics, particularly in set theory and model theory, there are at least three notions of stationary set:Classical notionIf kappa is a cardinal of uncountable cofinality, Csubseteqkappa, and C intersects every club in kappa, then C is… …
27Tree (set theory) — In set theory, a tree is a partially ordered set (poset) ( T …
28Descriptive set theory — In mathematical logic, descriptive set theory is the study of certain classes of well behaved subsets of the real line and other Polish spaces. As well as being one of the primary areas of research in set theory, it has applications to other… …
29Infinite set — In set theory, an infinite set is a set that is not a finite set. Infinite sets may be countable or uncountable. Some examples are: * the set of all integers, {..., 1, 0, 1, 2, ...}, is a countably infinite set; and * the set of all real numbers… …
30Ideal (set theory) — In the mathematical field of set theory, an ideal is a collection of sets that are considered to be small or negligible . Every subset of an element of the ideal must also be in the ideal (this codifies the idea that an ideal is a notion of… …
