ABSTRACT While the identification of nonlinear dynamical systems is a fundamental building block of model-based reinforcement learning and feedback control, its sample complexity is only understood for systems that either have discrete states and actions or for systems that can be identified from data generated by i.i.d. random inputs. Nonetheless, many interesting dynamical systems have…

ABSTRACT We study generalization properties of weakly supervised learning. That is, learning where only a few true labels are present for a task of interest but many more “weak” labels are available. In particular, we show that embeddings trained using weak labels only can be fine-tuned on the downstream task of interest at the fast…

ABSTRACT While stochastic gradient descent (SGD) is still the de facto algorithm in deep learning, adaptive methods like Adam have been observed to outperform SGD across important tasks, such as NLP models. The settings under which SGD performs poorly in comparison to adaptive methods are not well understood yet. Instead, recent theoretical progress shows that…

ABSTRACT Low-rank approximation of the Gaussian kernel is a core component of many data-science algorithms. Often the approximation is desired over an algebraic variety (e.g., in problems involving sparse data or low-rank data). Can better approximations be obtained in this setting? In this talk, I’ll show that the answer is yes: The improvement is exponential…

ABSTRACT Social media platforms moderate content using a process known as algorithmic filtering (AF). While AF has the potential to greatly improve the user experience, it has also drawn intense scrutiny for its roles in, for example, spreading fake news, amplifying hate speech, and facilitating digital red-lining. However, regulating AF can be harmful to the…