In terms of discovering materials which are chemically distinct from existing materials, train contribution to validation log density is the preferred proxy. We note that each of the proxies produce distinct plots. In the case of Figure , clusters tend to be stratified horizontally, whereas in Figure , cluster shapes exhibit similar orientations. As expected (Section 3.1), unclassified points appear frequently at or near the first Pareto front owing to the fact that unclassified points are likely to have a lower density proxy and therefore higher score. By contrast, unclassified points appear infrequently at or near the latter Pareto front. Additionally, the unique list of clusters present at the Pareto front are different for each plot. In other words, these are two types of chemical uniqueness -the first emphasizing chemical "distance" from other compounds and the latter emphasizing performance superiority over chemically similar compounds. We believe that either may be successfully used in the domain of materials discovery.