\begin{slide}{violet}
\violet
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\end{center}
Hopfield: if $T$ is symmetric, 0 diag., and amps are ``high gain'' mode,
then the stable output states are binary \{-1,1\}, and are local min. of
$$
E(\theta) = (-1/2)\sum_{i=0}^{N-1}\sum_{j=0}^{N-1} T_{ij}\theta_i\theta_j - \sum_{i=0}^{N-1} \theta_i I_i
$$
\end{slide}
