Difference between revisions of "Dense"
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+ | Let <math>X</math> be a [[topological space]] and <math>S</math> be a [[subspace]] of <math>X</math>. Then <math>S</math> is '''dense''' in <math>X</math> if, for any <math>x\in X</math> and any [[open set|open]] neighborhood <math>U\ni x</math>, <math>U\cap S\neq\varnothing</math>. For example, the [[rational number]]s are dense in the [[real number]]s. |
Latest revision as of 15:42, 18 August 2006
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Let be a topological space and be a subspace of . Then is dense in if, for any and any open neighborhood , . For example, the rational numbers are dense in the real numbers.