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open set
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open set

 * References


OPEN SET

mathematics
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LEARN ABOUT THIS TOPIC IN THESE ARTICLES:


DEFINING TOPOLOGICAL SPACES

 * 
   In topology: Topological space
   
   …sets in T are called open sets and T is called a topology on X. For example,
   the real number line becomes a topological space when its topology is
   specified as the collection of all possible unions of open intervals—such as
   (−5, 2), (1/2, π), (0, Square root of√2), …. (An analogous…
   
   Read More
 * In Hausdorff space
   
   …specified collection of subsets, called open sets, that satisfy three
   axioms: (1) the set itself and the empty set are open sets, (2) the
   intersection of a finite number of open sets is open, and (3) the union of
   any collection of open sets is an open set. A Hausdorff…
   
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