Closed set

Revision as of 12:10, 27 February 2010 by Azjps (talk | contribs) (create)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

In topology, a closed set is the complement of an open set.

Equivalently, a set is closed if it contains all of its limit points, or if its closure is equal to itself.

Under the standard topology of the real line, a closed set is the union of a number of disjoint closed intervals and closed rays.

This article is a stub. Help us out by expanding it.