  First Laszlo Szekely and more recently Saharon Shelah and Alexander Soifer
have presented examples of infinite graphs whose chromatic numbers depend on
the axioms chosen for set theory. The existence of such graphs may be relevant
to the Chromatic Number of the Plane problem. In this paper we construct a new
class of graphs with ambiguous chromatic number. They are unit distance graphs
with vertex set R^n, and hence may be seen as further evidence that the
chromatic number of the plane might depend on set theory.
