set of rational numbers
41Number system — This article is about different sets of numbers. For different methods of expressing numbers with symbols, see numeral system. In mathematics, a number system is a set of numbers, (in the broadest sense of the word), together with one or more… …
42Complete metric space — Cauchy completion redirects here. For the use in category theory, see Karoubi envelope. In mathematical analysis, a metric space M is called complete (or Cauchy) if every Cauchy sequence of points in M has a limit that is also in M or,… …
43Floating point — In computing, floating point describes a method of representing real numbers in a way that can support a wide range of values. Numbers are, in general, represented approximately to a fixed number of significant digits and scaled using an exponent …
44Addition — is the mathematical process of putting things together. The plus sign + means that two numbers are added together. For example, in the picture on the right, there are 3 + 2 apples meaning three apples and two other apples which is the same as… …
45Continuum hypothesis — This article is about the hypothesis in set theory. For the assumption in fluid mechanics, see Fluid mechanics. In mathematics, the continuum hypothesis (abbreviated CH) is a hypothesis, advanced by Georg Cantor in 1877[citation needed], about… …
46Fraction (mathematics) — A cake with one quarter removed. The remaining three quarters are shown. Dotted lines indicate where the cake may be cut in order to divide it into equal parts. Each quarter of the cake is denoted by the fraction 1/4. A fraction (from Latin:… …
47Dedekind–MacNeille completion — The Hasse diagram of a partially ordered set (left) and its Dedekind–MacNeille completion (right). In order theoretic mathematics, the Dedekind–MacNeille completion of a partially ordered set (also called the completion by cuts or normal… …
48Cantor , Georg Ferdinand Ludwig Philipp — (1845–1918) German mathematician The son of a prosperous merchant of St. Petersburg, at that time the capital of Russia, Cantor was educated at the University of Berlin where he completed his PhD in 1868. In 1870 he joined the faculty of the… …
49Binary relation — Relation (mathematics) redirects here. For a more general notion of relation, see Finitary relation. For a more combinatorial viewpoint, see Theory of relations. In mathematics, a binary relation on a set A is a collection of ordered pairs of… …
50Supremum — In mathematics, given a subset S of a partially ordered set T , the supremum (sup) of S , if it exists, is the least element of T that is greater than or equal to each element of S . Consequently, the supremum is also referred to as the least… …
