Speaker: Tim Griffin, University of Cambridge Title: Exploring the Stratified Shortest Paths Problem Date/time: 3pm Tuesday May 4 Location: room 302 in the Computer Science building Abstract: The Border Gateway Protocol (BGP) is the keystone among Internet routing protocols as it maintains connectivity in the entire global Internet. BGP has evolved into a rather mysterious beast. Theoretical work over the last ten years has made it clear that BGP represents something novel in the context of routing protocols: BGP does not compute globally optimal paths, but only locally optimal paths. The talk will explain how this exotic type of routing can be understood in an algebraic setting. The Stratified Shortest-Paths Problem (SSPP) is presented as a very simple example of this type of algebra. The SSPP is meant to capture the essence of a BGP-like path problem without BGP's many operational complexities. Bio: Tim Griffin is a Senior Lecturer and Fellow at King's College, University of Cambridge. His research interests include network protocol design and analysis, with a focus on Internet routing protocols.