• Multi-fidelity BO. Often, we have a choice of multiple experimental methods to evaluate the property of an NPM. These methods usually involve a tradeoff in resource cost and the accuracy of the evaluation. For example, a molecular simulation of gas adsorption in an NPM is a low-fidelity experiment (cheap, but inaccurate) while measurement of gas adsorption in an NPM in a physical laboratory is a high-fidelity experiment (costly, but accurate). Intuitively, it is possible to leverage low-fidelity experiments to prune NPMs with low property values and to identify promising NPM candidates that can be searched further using high-fidelity experiments. In multi-fidelity BO [ -], we select both an NPM to evaluate and the fidelity of the experiment in each iteration. This allows optimization of the overall resource cost of experiments-of both low-and high-fidelity-for identifying high-performing NPMs.