A point which is a member of the set closure of a given set and the set closure of its complement set. If is a subset of , then a point is a boundary point of if every neighborhood of contains at least one point in and at least one point not in .

# Boundary Point

## See also

Boundary## Explore with Wolfram|Alpha

## Cite this as:

Weisstein, Eric W. "Boundary Point." From
*MathWorld*--A Wolfram Web Resource. https://mathworld.wolfram.com/BoundaryPoint.html