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Topologically closed
From Mathematics Is A Science
Revision as of 22:36, 3 September 2011 by imported>Tom
Given a topological space $X$, its subset $A$ is called sequentially closed if taking the limits of sequences of the elements of $A$ won't result in elements outside of $A$.
Allowing transfinite sequences results in a concept equivalent to the usual definition closed set, see Open and closed sets.
Compare to algebraically closed subsets.