Learning Robust to Distributional Uncertainties and Adversarial Data

Successful training of data-intensive deep neural networks critically rely on vast, clean, and high-quality datasets. In practice however, their reliability diminishes, particularly with noisy, outlier-corrupted data samples encountered in testing. This challenge intensifies when dealing with anonymized, heterogeneous data sets stored across geographically distinct locations due to, e.g., privacy concerns. This present paper introduces robust learning frameworks tailored for centralized and federated learning scenarios. Our goal is to fortify model resilience with a focus that lies in (i) addressing distribution shifts from training to inference time; and, (ii) ensuring test-time robustness, when a trained model may encounter outliers or adversarially contaminated test data samples. To this aim, we start with a centralized setting where the true data distribution is considered unknown, but residing within a Wasserstein ball centered at the empirical distribution. We obtain robust models by minimizing the worst-case expected loss within this ball, yielding an intractable infinite-dimensional optimization problem. Upon leverage the strong duality condition, we arrive at a tractable surrogate learning problem. We develop two stochastic primal-dual algorithms to solve the resultant problem: one for
$\epsilon $
-accurate convex sub-problems and another for a single gradient ascent step. We further develop a distributionally robust federated learning framework to learn robust model using heterogeneous data sets stored at distinct locations by solving per-learner’s sub-problems locally, offering robustness with modest computational overhead and considering data distribution. Numerical tests corroborate merits of our training algorithms against distributional uncertainties and adversarially corrupted test data samples.