# 5 – Aut | $\nps$

There is a natural chamber sub-structure over $\nps$,
bounded by $(-2)$-walls. That is,

$$\nps = \bigcup_{D\in \mathcal{C}}D$$ for a sub-collection $\mathcal{C}\subset\mathcal{C}_S$ of the $\ps$-chamber structure.