Sampled molecules not included in GDB-13 were labeled with the topological and chemical filters used in the enumeration process of GDB-13 that they broke . The molecules with disallowed topology were labelled the following way: carbon skeletons from all the molecules in GDB-13 were calculated and compared to the carbon skeletons for each sampled molecule, labelling the molecules whose skeleton was not in GDB-13. All tautomers for all the molecules were calculated with MolVS [34] 0.1.1. For each molecule, if one tautomer was part of GDB-13, the molecule was labelled as a tautomer. Molecules with disallowed functional groups, heteroatom configurations or bonds were detected using SMARTS.