The UC Berkeley combinatorics seminar
|DATE||SPEAKER||TITLE (click to show abstract)|
|January 25th||Eugene Gorsky UC Davis||
Algebraic weaves and braid varietiesIn the talk I will define braid varieties, a class of affine algebraic varieties associated to positive braids, and develop a Soergel-like diagrammatic calculus for correspondences between them. The braid varieties are closely related to augmentation varieties for Legendrian links, and the correspondences provide an algebraic machinery to study exact Lagrangian fillings of such links. This is a joint work with Roger Casals, Mikhail Gorsky and Jose Simental Rodriguez.
|February 1st||Christopher Ryba UC Berkeley||
Stable characters from permutation patternsFor a fixed permutation σ∈Sk, let Nσ denote the function which counts occurrences of σ as a pattern in permutations from Sn. We study the expected value (and d-th moments) of Nσ on conjugacy classes of Sn and prove that the irreducible character support of these class functions stabilizes as n grows. This says that there is a single polynomial in the variables n,m1,…,mdk which computes these moments on any conjugacy class (of cycle type 1^m1,2^m2,⋯) of any symmetric group. Our proof is, to our knowledge, the first application of partition algebras to the study of permutation patterns. This is joint work with Christian Gaetz.
|February 8th||Camille Combe Universite de Paris||February 15th||Academic Holiday - no talk||February 22nd||Nikhil Srivastava UC Berkeley||March 1st||Jonathan Novak UCSD||March 8th||Alejandro Morales UMass Amherst||March 15th||Raul Penaguiao SFSU||March 22nd||Spring Recess - no talk||March 29th||Foster Tom UC Berkeley||April 5th||Jeremy Meza UC Berkeley||April 12th||Zajj Daugherty CUNY||April 19th||Kelly Isham UC Irvine||April 26th||Yulia Alexandr UC Berkeley||May 3rd||Vasu Tewari University of Hawai'i|