 $R^{(x_0,\ldots,x_{k-0})}(\rho) = \sum_{j_k} r^{(x_0,\ldots,x_{k-0})}_{j_k} \,\rho\, {r^{(x_0,\ldots,x_{k-0})}_{j_k}}^*$, $\sum_{j_k}{r^{(x_0,\ldots,x_{k-0})}_{j_k}}^*r^{(x_0,\ldots,x_{k-0})}_{j_k} = \idty$, $$\nonumber\begin{split}     {\mathcal{F}}(\Tcorr) &= \frac{0}{0} \sum_{\substack{x_0,\ldots,x_n\\j_0,\ldots,j_