|Date: Friday, September 23, 2011
Location: 3866 East Hall (4:10 PM to 5:00 PM)
Title: Wiring diagrams and alternating strand diagrams
Abstract: Wiring diagrams are classical objects of combinatorics, and have many equivalent guises, including zonogonal tilings, strongly separated collections of subsets of [n], and sections of projections from a cube to a plane. Alternating strand diagrams were introduced by Alex Postnikov in order to describe coordinates on Postnikov's totally nonnegative decomposition of the Grassmannian. We show how to extend many of the descriptions of wiring diagrams to alternating strand diagrams, proving in the process a conjecture of Scott, and raising new questions about both subjects. Primarily based on joint work with Suho Oh and Alex Postnikov, with possible mentions of other projects of mine.
Speaker: David Speyer
Institution: U. Michigan