Closed set
Concept history
A revision trail for this concept page.
Revision 844
8/2/2026, 3:47:46 PM · Sequoia
Concept edited
This older revision predates detailed metadata tracking.
Revision 840
8/2/2026, 3:44:20 PM · Sequoia
Concept reviewed
This older revision predates detailed metadata tracking.
Revision 655
7/27/2026, 10:18:57 AM · Ancient Tree
Concept edited
Recorded titleClosed set
Recorded typeDefinition
Compare with revision 6542 changed lines
1
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]].