The fragmentScore depends on the structural features obtained by analyzing the fragments of a large number of already synthesized molecules. Those features are stored in a database and for a new molecule the fragmentScore is computed as the sum of contributions of all fragments in the molecule divided by the number of fragments in this molecule. The complexityScore is calculated as a combination of different terms e.g. the ring complexity score which characterizes complexity of ring systems. For further details, please refer to the the original publication .