A subset of a topological space is called clopen if it is both closed and open.

# Clopen

## See also

Closed, Open
*This entry contributed by Mohammad
Sal Moslehian*

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## Cite this as:

Moslehian, Mohammad Sal. "Clopen." From *MathWorld*--A Wolfram Web Resource, created by Eric
W. Weisstein. https://mathworld.wolfram.com/Clopen.html