A. Replicating a SMARTS hierarchy from a SMIRNOFF hierarchy TABLE II. BESMARTS accuracy (%) against SMIRNOFF torsion labels. Accuracy was measured as the percentage of SMARTS patterns that mapped to exactly one Sage torsion SMARTS. The SMARTS hierarchies were built using a limit on both b , the number of bits search, and the depth graph which determines how far the chemical environment can extend. Accuracies are reported per binary reduction level, where the number of molecules corresponds to O(2 k ) for k = log 2 N where the number of molecules N = 49. The first test for the BESMARTS method is establishing if we can build a SMARTS hierarchy that can recapitulate a chemical perception model based on an existing SMARTS hierarchy. Success in such a test would indicate that BESMARTS can search chemical space effectively to find the distinguishing characteristics that the reference model encodes. Here we use the Sage set of parameters, the latest SMIRNOFF-format force field from the Open Force Field Consortium. Comparing to this model is interesting because nearly all of the SMARTS patterns were hand-curated by experts. An accurate reproduction of the Sage hierarchy therefore indicates that all chemical environments deemed important by experts were captured here. Because the reference model is based on SMARTS, any inaccuracy of this test indicates that the BESMARTS approach is not searching SMARTS effectively and/or the Sage SMARTS are too complex for this approach. We perform this test using the torsion parameters of the Sage force field, since these are the most complicated SMARTS and also the most numerous. The results are shown in Tbl. II.