Events for 11/27/2018 from all calendars

Center for Approximation and Mathematical Data Analytics

Time: 1:00PM - 2:00PM

Location: BLOC 220

Speaker: David Rolnick, Univ. Penn.

Title: Reducing catastrophic forgetting in reinforcement learning

Abstract: Deep learning approaches often fail when the data changes over time. This happens because the weights in a neural network will overwrite what they learned in the past with what they learned most recently. This phenomenon, known as catastrophic forgetting, presents a major impediment to learning in real-world situations. We examine this issue in the context of reinforcement learning, where the goal is to learn one game, then another, and then come back to the first game without forgetting it. While many methods to counteract catastrophic forgetting have been proposed, we find that a simple approach based upon experience replay performs as well or better while requiring less task information. This work is part of a collaboration with Google DeepMind. No background knowledge on reinforcement learning is assumed.

Colloquium - Khrystyna Serhiyenko

Time: 4:00PM - 5:00PM

Location: BLOC 220

Speaker: Khrystyna Serhiyenko, University of California, Berkeley

Description:
Title: Cluster structures in Grassmannian and Schubert varieties
Astract: Cluster algebras are commutative rings defined by a set of generators and relations and equipped with a rich combinatorial structure. It turns out that coordinate rings of many important variates from Lie theory are cluster algebras. In this talk, we will discuss cluster structures in Schubert varieties of the Grassmannian and their categorification via representation theory of preprojective algebras. In particular, we will relate combinatorics of Postnikov's plabic graphs and recent work of Leclerc on cluster structures in flag varieties. This naturally generalizes the known results for the Grassmannian, and has been conjectured for some time. We will also examine new connections between Grassmannians and certain combinatorial objects called $sl_k$ friezes.

Student/Postdoc Working Geometry Seminar

Time: 5:00PM - 6:00PM

Location: BLOC 628

Speaker: JM Landsberg

Title: News from Warsaw: apolarity and border rank