 This is equivalent to the number of nodes on the Coxeter diagram, or the number of hyperplanes in the Wythoffian construction.Because ("n"+1)-dimensional polytopes are tilings of "n"-dimensional spherical space, tilings of "n"-dimensional Euclidean and hyperbolic space are also considered to be ("n"+1)-dimensional.Hence, the tilings of two-dimensional space are grouped with the three-dimensional solids.