Definable Real Number

(Set Theory)

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Set Theory
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What is Definable real number?

Informally, a definable real number is a real number that can be uniquely specified by its description. The description may be expressed as a construction or as a formula of a formal language. For example, the positive square root of 2, , can be defined as the unique positive solution to the equation , and it can be constructed with a compass and straightedge. Different choices of a formal language or its interpretation can give rise to different notions of definability. Specific varieties of definable numbers include the constructible numbers of geometry, the algebraic numbers, and the computable numbers.

Technology Types

set theory


Definable numberDefinable numbersUndefinable numberUndefinable numbers


Difinebla nombro (eo)정의 가능한 수 (ko)可定义数 (zh)

Tech Info

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