A closed set contains all its boundary points
Closed set
A closed set contains all its boundary points
In topology, a closed set is defined as a set that contains all its boundary points. This means that if a point is on the boundary of a closed set, it must be included within the set itself. Understanding this concept is fundamental to grasping the broader principles of topology and the behavior of sets within topological spaces.
Example
Consider the closed interval [a, b] in the real line. This interval includes both points a and b, which are its boundary points. Therefore, [a, b] is a closed set because it contains all its boundary points.
Recognizing that closed sets contain all their boundary points helps in identifying and working with closed sets in various topological contexts.
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