Presented By: Combinatorics Seminar - Department of Mathematics
An introduction to webs (Combinatorics seminar)
Julianna Tymoczko (Smith)
The combinatorial spider is a diagrammatic category that encodes quantum sl(n) representations, and was formalized by Kuperberg. Webs are certain directed planar graphs (with edge-weights), corresponding to the morphisms in this category, and endowed with skein-type relations that indicate algebraic equivalences. Webs are well-understood in the case n=2, when they are essentially noncrossing matchings (or Temperley-Lieb diagrams), and in the substantially more complicated case n=3.
In this talk, we sketch some of the historical evolution of webs, including work of Kuperberg, Khovanov, Fontaine, and Cautis-Kamnitzer-Morrison, as well as the convergence with a collection of combinatorial ideas about plabic graphs from Postnikov, Fomin-Pylyavskyy, Fraser-Lam-Le, and others. We also describe a new approach, joint with Heather M. Russell, that uses a set of colored paths called \emph{strands} to give a global construction for webs, via graph-theoretic and combinatorial notions generalized from smaller dimensions. Time permitting, we'll also allude to connections to algebraic geometry.
In this talk, we sketch some of the historical evolution of webs, including work of Kuperberg, Khovanov, Fontaine, and Cautis-Kamnitzer-Morrison, as well as the convergence with a collection of combinatorial ideas about plabic graphs from Postnikov, Fomin-Pylyavskyy, Fraser-Lam-Le, and others. We also describe a new approach, joint with Heather M. Russell, that uses a set of colored paths called \emph{strands} to give a global construction for webs, via graph-theoretic and combinatorial notions generalized from smaller dimensions. Time permitting, we'll also allude to connections to algebraic geometry.