Wednesday, 9 October 2013

general topology - Limit sequence sets

In my measure theory book I came across the following definition:
Let (An)n1 be a sequence of subsets of some set X. Define:



lim supnAn:=n1knAk



lim infnAn:=n1knAk



Call the sequence convergent if lim supnAn=lim infnAn , in which case we define limnAn:=lim supnAn



My question is, does this notion of convergence correspond to some sort of metric on the set of subsets of X, or is it completely unrelated to the usual concept of a limit? Thanks

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