^{H^0}_\eta (\gamma_x)$ for all $\eta \in \mathcal{N}( {{\mathbb R}}^d \times \{+,-\})$ and $\gamma_x \in  {{\mathbb R}}^d \times \{+,-\}$ such that both $\eta$ and $\eta + \delta_{\gamma_x}$ are outside the dynamically impossible set $