Closed set
Concept history
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Revision 655
7/27/2026, 10:18:57 AM · Ancient Tree
Concept edited
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Let $X$ be a [[Topological space|topological space]]. A subset $A\subseteq X$ is closed in $X$ if its [[Complement|complement]] $X\backslash A$ is [[Open set|open]].1
Let $X$ be a [[Topological space|topological space]]. A subset $A\subseteq X$ is closed in $X$ if its [[Complement of a subset|complement]] $X\backslash A$ is [[Open set|open]].Revision 654
7/27/2026, 10:18:47 AM · Ancient Tree
Concept created
Let $X$ be a [[Topological space|topological space]]. A subset $A\subseteq X$ is closed in $X$ if its [[Complement|complement]] $X\backslash A$ is [[Open set|open]].