In GuacaMol, molecules highly similar to the target (bit-vector Tanimoto similarity above 0.323) are removed from the population of initial molecules to increase the effectiveness of the benchmarks. That initial population is randomly selected from ChEMBL, which exclusively consists of molecules that have both been synthesised in a lab and tested against biological targets. To set up GB-BI for the GuacaMol rediscovery benchmark of Troglitazone, we chose the feature space to be spanned by molecular mass, 225 u. to 555 u., a lipophilicity, log P = -0.4 to log P = 5.6, a topological polar surface area (TPSA) between 0 Å 2 and 140 Å 2 , and a Wildman-Crippen molar refractivity value between 40 and 130. The ranges were chosen to roughly correspond to properties of orally active drugs, and in accordance with our previous work the archive was set up with 150 niches.