  These contain introductory points on two issues that we shall revisit  (again, in supplementary documents)  at the end of this entry.    The reason for the separation is that   the issues discussed pertain to game theory and measure theory  on the one hand, and fractals and metric spaces on the other.  That is, the discussions are not entirely set theoretic.    In addition, the mathematical prerequisites for all our supplements are   greater than for the main body of this entry.   They may be omitted without losing the main thread. However, we emphasize  that the  overall theory presented in this entry does treat all of these  instances of circularity “under the same roof.”  