Definition:Regular Open Set
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Definition
Let $T$ be a topological space.
Let $A \subseteq T$.
Then $A$ is regular open in $T$ if and only if:
- $A = A^{- \circ}$
That is, if and only if $A$ equals the interior of its closure.
Also see
- Results about regular open sets can be found here.
Sources
- 1978: Lynn Arthur Steen and J. Arthur Seebach, Jr.: Counterexamples in Topology (2nd ed.) ... (previous) ... (next): Part $\text I$: Basic Definitions: Section $1$: General Introduction: Closures and Interiors