The maximum complexity, i.e., the maximum number of operators in one combined model, was set to 10. For the singlet exciton energy, triplet exciton energy, and singlet exciton binding energy a total of roughly 5 × 10 2 , 4 × 10 5 , and 6 × 10 10 features were generated by SISSO with a rung of 1, 2, and 3, respectively. For the singlet-triplet gap, a total of roughly 6.5 × 10 2 , 7.5 × 10 5 , and 2 × 10 11 features were generated by SISSO with a Rung of 1, 2, and 3, respectively.