The Conditional Entropy Bottleneck
This addresses critical reliability issues in machine learning models, offering a novel approach to enhance robustness, though it builds incrementally on the Information Bottleneck framework.
The paper tackles failures in robust generalization, such as adversarial vulnerability and poor out-of-distribution detection, by proposing the Conditional Entropy Bottleneck (CEB) objective, which shows strong empirical improvements across various datasets and robustness challenges.
Much of the field of Machine Learning exhibits a prominent set of failure modes, including vulnerability to adversarial examples, poor out-of-distribution (OoD) detection, miscalibration, and willingness to memorize random labelings of datasets. We characterize these as failures of robust generalization, which extends the traditional measure of generalization as accuracy or related metrics on a held-out set. We hypothesize that these failures to robustly generalize are due to the learning systems retaining too much information about the training data. To test this hypothesis, we propose the Minimum Necessary Information (MNI) criterion for evaluating the quality of a model. In order to train models that perform well with respect to the MNI criterion, we present a new objective function, the Conditional Entropy Bottleneck (CEB), which is closely related to the Information Bottleneck (IB). We experimentally test our hypothesis by comparing the performance of CEB models with deterministic models and Variational Information Bottleneck (VIB) models on a variety of different datasets and robustness challenges. We find strong empirical evidence supporting our hypothesis that MNI models improve on these problems of robust generalization.