# Residuals

Most of the discussion in these pages is about what could be done with a fixed store of sensory+motivational contexts ($\mathbf{W}$). In that case, what matters is that the current context, $\vec{r}$, identifies a unique 'recognised context', $\mathbf{W(k,:)}$. Of course, the current context, will never be quite the same as the stored context; the difference, or residual, is important for learning and memory.