To exemplify the predictions of 'Ring Breaker', we retrieved examples from the organic chemistry literature for which commonly used ring-forming reactions were used (Figure ). We assessed each substrate against each of the three methods of prioritization mentioned previously, both for the USPTO and Reaxys datasets (Figure ). As mentioned in the overview of template-based retrosynthesis planning, not all templates are applicable for a given compound. Therefore, using a brute force application we exhaustively applied all the templates underlying each model to determine the maximum number of templates that were applicable. Figure shows the results obtained are as expected, the standard and filtered models have the same underlying set of templates and have not been constrained to those corresponding to ring formations. Therefore, both models have a higher number of applicable templates than the Ring Breaker model, for which only templates that have been used in the context of ring formations were considered. The same pattern is observed for the Reaxys dataset as shown in Figure . More importantly, the maximum number of applicable templates that correspond to ring formations is a much smaller fraction of the total amount as shown in Figure and Figure . : Application of all templates underlying each of the models, 'Ring Breaker', standard, and filtered models, to the substrates in Figure . a) For the USPTO dataset, the maximum number of templates the can be applied from the standard and filtered models far exceeds that from the 'Ring Breaker' model. This is because of the larger number of templates available to the standard and filtered models. The number of templates that can be applied in the top 50 predictions (b) which also correspond to ring formations, is a fraction of those that can be applied by brute force in silico. The same is observed for models built on the Reaxys dataset as shown in c) and d). The discrepancy between the top 50 predictions of the 'Ring Breaker' model and standard and filtered models is described in SI_3 of the supporting information.