The set of points, known as boundary points, which are members of the set closure of a given set and the set closure of its complement set. The boundary is sometimes called the frontier.

# Boundary

## See also

Boundary Conditions, Boundary Map, Boundary Point, Boundary Set, Natural Boundary, Surgery## Explore with Wolfram|Alpha

## Cite this as:

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