\item Soundness: if $P^*$ convinces $V$ with probability $p > \frac{1}{2}$
then we can, in theory, run $P^*$ with (say) $c = 0$ and get $\gamma$.
We then \emph{rewind} $P^*$, give it $c = 1$, and get $\gamma \beta$,
\item Soundness: if $P^*$ convinces $V$ with probability $p > \frac{1}{2}$
then we can, in theory, run $P^*$ with (say) $c = 0$ and get $\gamma$.
We then \emph{rewind} $P^*$, give it $c = 1$, and get $\gamma \beta$,