For the test set of five compositions (Sr4Ti3O10, Y2TiO5, Y2Ti2O7, SrY2O4 and Y2O3), we compare performance on one key metric; the number of steps taken to identify the global minimum for each composition-policy pair, where each step consists of the structure modification via an action and subsequent local energy minimisation using GULP . Each step in the CSP run is followed by an accept / reject stage to determine whether to accept the new structure or retain the previous one (see Methods). As CSP codes are stochastic, multiple repeat runs are required to build up statistics. While there is no common standard for how many repeat calculations to perform when testing a CSP code, typical benchmarking examples perform ~ 30 -70 , in this work we perform 40 repeats for every composition and policy tested, for a total of 600 runs across the five compositions and calculate the "mean number of steps" Nmean for each composition-policy pair. Nmean represents how many steps FUSE needs on average to find the structure with the global minimum energy (Fig. ). For the majority of compositions, namely Sr4Ti3O10, Y2TiO5, Y2Ti2O7, SrY2O4, Nmean is calculated as the mean number of steps required to find the global minimum among all 40 runs. However, the Original policy is unable to attain the global minimum for SrY2O4 in 28 runs out of 40, given a minimum of 90,000 steps in the search, so the lower bound on Nmean is provided for this composition-policy pair calculated as the mean number of steps to completion among 12 successful and 28 stopped runs.