The similarity between individual pairs of USRCAT descriptors is canonically calculated by the USRscore 77 , a special variant of the Manhattan distance. In line with the use of USRscore for USRCAT descriptors, we use the Canberra distance Fig. Heatmaps for the mean values for the maximum fitness (upper, left) and the maximum error (bottom, left) are shown. Additional calculations were made to determine and show heatplots for the rate of rediscovery of Troglitazone (upper, right) and the average amount of fitness calls it requires (bottom, right). These four heatmaps reflect the performance of the various combinations of representations and acquisition functions for GB-BI based on ten independent runs for each combination. Darker hue's correspond to a better performance. Note that only successful Troglitazone rediscoveries were considered in computing the mean fitness call value, i.e. displayed values are excluding failed runs, but in the two cases were there was no successful rediscovery of Troglitazone at all, the mean fitness calls were fixed to the overall maximum (5000). For compactness and improved readability, SMILES and SELFIES are abbreviated to SMI and SLF, respectively.