Gon Buzaglo will present his General Exam "Online Control using Spectral Filtering" on Thursday, May 28, 2026 at 11:30 AM in CS 402. Committee Members: Elad Hazan (advisor), Mark Braverman, Clarence Rowley, Bartolomeo Stellato Abstract: We introduce a new algorithmic framework for controlling linear dynamical systems in adversarial environments. Our method achieves efficient online control with regret guarantees while improving the running-time dependence on the stability margin from polynomial to polylogarithmic. The approach is based on a novel convex relaxation that approximates linear control policies using a universal basis derived from the eigenstructure of a Hankel matrix, a technique which may be of independent interest. This yields a computationally efficient algorithm that matches the performance of prior online control methods while exponentially accelerating their runtime dependence on the stability margin. To demonstrate the generality of our approximation framework, we derive results for partial observation of the state and bandit feedback of the costs. Reading List: https://drive.google.com/file/d/1y6Bk6Bd0rduVU1kwgGVvk_0DdTxo857E/view?usp=s... Everyone is invited to attend the talk, and those faculty wishing to remain for the oral exam following are welcome to do so.