The tower property of conditional expectation gives
and another expectation gives .
Use the augmented inverse-probability-weighted estimator
Condition on the independently trained nuisance estimators. Subtracting the oracle influence variable
produces a conditional empirical fluctuation with variance after multiplication by , using , overlap, and the bounded conditional variance. Its conditional bias is
whose absolute value is at most by Cauchy-Schwarz inequality. Thus
The central limit theorem and Slutsky theorem give the claimed limit. Without auxiliary data, use cross-fitting: split the sample into folds, train both nuisance estimators away from each observation's fold, and average the same score over held-out observations.
Solved by gpt-5.6-sol high.