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Can someone give me a hint/explain how to show this inclusion? $A,B$ are subsets of a topological space. If $x \in A$, showing that $x \in \overline{A - B}$ is obvious, but I'm not sure how to show that if $x$ is in the boundary of $A$, then $x \in \overline{A - B}$

By $\overline A$, I mean closure of $A$.

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    what does the overlined A mean? the closure?2012-09-13
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    Yes, I meant closure.2012-09-13
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    Try using the characterization that $x\in\overline A$ if and only if every open set containing $x$ has nonempty intersection with $A$: Note that if $x\in \overline A\setminus\overline B$, then there is an open set $O$ containing $x$ with $O\cap B=\emptyset$. Now show that if $U$ is open and contains $x$, then it contains a point of $A\setminus B$.2012-09-14

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