Hebbian memory weights for a Hopfield network
= Hebbian memory weights for a Hopfield network
{c}
{title2=$w_{ij}=M^{-1}\sum_\mu\xi_i^\mu\xi_j^\mu,\quad i\ne j$}
For $M$ binary units and desired patterns $\xi^\mu$, use these symmetric weights and set $w_{ii}=0$. For one pattern, the field at that pattern is $(M-1)\xi_i/M$, so it is stable. Several patterns add cross-talk terms; storage by this rule alone does not guarantee stability of every arbitrary collection of patterns.