spatial regions $R_1$ and $R_2$ at time $t_1$, initially evolving independently, and let $I(R_1)$ and $I(R_2)$ be their respective future domains of influence. If these domains overlap at some later time $t_2$, the relative rate of evolution can matter: the data in $R_1$ at time $t_1$, for instance, will change the data in $I(R_1)\cap I(R_2)$ at time $t_2$, and thus the subsequent evolution of $R_2$. Using a term from computer science, Wall calls this the “race problem”: two independent regions are “racing” toward the intersection $I(R_1)\cap I(R_2)$ , and the one that gets there first determines the subsequent evolution. Such behavior, which is known to occur in particular models, clearly breaks diffeomorphism invariance; in an emergent gravity model, it would be interpreted as a failure of Hamiltonian constraints smeared by two different lapses to weakly commute. Avoiding this problem seems very difficult, requiring either an arbitrary division of space into nonoverlapping regions or the imposition of extremely delicate consistency conditions. It can be argued that these consistency conditions appear automatically for a “perfect action,” a discrete action that is already invariant under the full diffeomorphism group [@Dittrich0; @Dittrich4], but it is not clear how such a structure would arise from 