5. The enzyme enhancement addressed in this work is a two-objective problem, which precludes the identification of a unique "best" variant. The reason is obviously that each variant is given two scores (related to stability and catalysis) and there is no single variant that simultaneously displays the highest values for the two scores. Therefore, it is of interest in this context to briefly discuss how variant selection would be carried out when several properties are relevant for an intended application. In general, for multi-objective optimization problems, a global optimum cannot be generally identified. However, the Pareto front is a fundamental concept in engineering, including enzyme engineering, that, at a very basic level, provides a criterium to decide which variants within a set need to be considered for a practical application in a multi-objective optimization problem.