What are valences? I don't think it was defined prior to this.
I also thought extraordinary vertices are vertices that aren't degree 6, but it looks like prior to this, even in a normal grid of squares, each vertex is degree 4, so aren't they all extraordinary vertices?
Oops I just saw later "valence of vertex" so I'm assuming that's the same meaning as "degree of vertex"
Also confused...2 extraordinary with degree 5? 6 non-quad face?