set of rational numbers
61Portal:Mathematics — Wikipedia portals: Culture Geography Health History Mathematics Natural sciences People Philosophy Religion Society Technology …
62Closure (topology) — For other uses, see Closure (disambiguation). In mathematics, the closure of a subset S in a topological space consists of all points in S plus the limit points of S. Intuitively, these are all the points that are near S. A point which is in the… …
63Completeness axiom — In mathematics the completeness axiom, also called Dedekind completeness of the real numbers, is a fundamental property of the set R of real numbers. It is the property that distinguishes R from other ordered fields, especially from the set of… …
64infinity — /in fin i tee/, n., pl. infinities. 1. the quality or state of being infinite. 2. something that is infinite. 3. infinite space, time, or quantity. 4. an infinite extent, amount, or number. 5. an indefinitely great amount or number. 6. Math. a.… …
65Jordan measure — In mathematics, the Jordan measure (also known as the Jordan content) is an extension of the notion of size (length, area, volume) to shapes more complicated than, for example, a triangle, disk, or parallelipiped. It turns out that for a set to… …
66Cantor's first uncountability proof — Georg Cantor s first uncountability proof demonstrates that the set of all real numbers is uncountable. Cantor formulated the proof in December 1873 and published it in 1874 in Crelle s Journal [cite… …
67Dense-in-itself — In mathematics, a subset A of a topological space is said to be dense in itself if A contains no isolated points. Every dense in itself closed set is perfect. Conversely, every perfect set is dense in itself. A simple example of a set which is… …
68Chaitin's constant — In the computer science subfield of algorithmic information theory, a Chaitin constant or halting probability is a real number that informally represents the probability that a randomly constructed program will halt. These numbers are formed from …
69Fuzzy logic — is a form of multi valued logic derived from fuzzy set theory to deal with reasoning that is approximate rather than precise. Just as in fuzzy set theory the set membership values can range (inclusively) between 0 and 1, in fuzzy logic the degree …
70Essential supremum and essential infimum — In mathematics, the concepts of essential supremum and essential infimum are related to the notions of supremum and infimum, but the former are more relevant in measure theory, where one often deals with statements which are not valid everywhere …
