ÄÅ 9:;9<# (NAP-XPS): surface charge transfer c M,$" OPQ (XPS): surface redox activity, surface restructuring c M,@"J OPQ , c M,e#C OPQ (NAP-XPS): surface redox activity, surface restructuring a Optimal model complexity with respect to predictability identified by leave-one-material-out cross-validation. 6 and 5 correspond to the depth of the symbolic-regression tree and to the descriptor dimension, respectively. b With the application of multi-task SISSO, the fitted model coefficients (coeff.) are allowed to adapt to each reaction, i.e., -0 = -0 (7), where 7 stands for reaction (ethane, propane or n-butane oxidation), or simultaneously to each reaction and temperature, i.e., -0 =â (r, T), in the case of the model X 9:;9<# ()((* . The best identified model for the yield of CO and CO2 is 2-D and it is shown in eq. 3 of Table . The Y D*I ()((* expression contains the carbon and RAE surface contents on the fresh and activated catalysts under UHV (L M,$" D ,and L M,9BC OPQ , respectively), the surface RAE oxidation state of the activated catalyst under UHV (c M,9BC OPQ ) and the valence-band onset under alkane-rich feed (ÄÅ 9:;9<# ). These key parameters reflect that the formation of the combustion products is governed OPQ , respectively, as well as the charge-transfer from the surface to adsorbed species, encoded by c M,9BC OPQ , and ÄÅ @"J . The 12 catalysts are represented in the coordinates of the 2-D descriptor in Fig. . They are roughly located in three portions of the plot, containing (i) the combustion catalysts MnWO4 and SmMnO3, (ii) VPP, a-VPP and V2O5, which produce significant COx in ethane and propane oxidation and (ii) the remaining catalysts, which provide low = D* y . In this "map of potential catalysts", the values predicted by the model (Y D*I ()((* ) are indicated by the grey scale. Interestingly, the gradient of Y D*I ()((* , determined by the reactiondependent fitted coefficients, shows that 1 z pÇ y , which contains the electronic properties Ω M,9BC OPQ and ÄÅ @"J , becomes more important than 1 4 ò pÇ y , as one moves from ethane, to propane and n-butane oxidation. This can be related to the number of electrons that needs to be transferred from the catalyst surface to the adsorbed species in order to achieve combustion, which increases in the order C2 < C3 < C4 oxidation.