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\begin{frame}{Russell's Barber Paradox}
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What does the law require of the barber?\pause{}

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\begin{description}
\item[Case 1: The barber shaves himself.]\mbox{}\pause
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Then he does \mediumblue{\eqref{self-shaved}} and \mediumblue{\eqref{barber-shaved}}.
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By doing \alert{both \eqref{self-shaved} and \eqref{barber-shaved}},
he violates the law that only permits exactly one of these options.
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$\;\;\alert{\xmark}$
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\item[Case 2: The barber does not shave himself.]\mbox{}\pause
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Then he does not do \mediumblue{\eqref{self-shaved}}.
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As he is the barber, he also is not shaved by the barber.
So he does not do \mediumblue{\eqref{barber-shaved}}.
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By doing \alert{neither \eqref{self-shaved} nor \eqref{barber-shaved}},
the law is again violated.
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$\;\;\alert{\xmark}$
\end{description}
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\end{frame}