This can be represented as follows:
\[
\begin{tikzpicture}
\draw (-2,-2) rectangle (2,2);
\node at (-2,2) [above left] {$U$};
\draw (-0.5,0) circle (1);
\node at (-0.5,0) {$A$};
\draw (0.5,0) circle (1);
\node at (0.5,0) {$B$};
\end{tikzpicture}
\]
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