Although we omit host structures with cations outside the training set in this study, adding a small number of training structures in the future (the full search space from Figure ) could further expand the model's applicability. Figure shows the predicted ∆ ĤO d K vs. ∆H f , and, although correlation is evident across the entire enthalpy range, there is little correlation within [2.3, 4.0] eV. Furthermore, a simple model using features derived only from the host composition would clearly be insufficient due to an inability to distinguish individual oxygen vacancies. Within a single structure, these can span a very large range as shown for the min, median, and max predictions for MP structure mp-1247717 (Ca 4 Mn 3 AlO 11 ).