So when I typed the equation here:
$$ \text{Tr } \frac{\partial }{\partial \sum_i \beta_i} \Big ( \sum_{i}^N(I + - \beta_i \rho H +\frac{( \beta_i \rho H)^2}{2!} + \dots \Big )_{G.M} = \text{Tr } \frac{\partial }{\partial \sum_i \beta_i} \Big (I_f - \beta_f \rho_f H_f + \dots \Big )_{G.M} $$
The G.M at the corner does not appear? Why is that?