The UC Berkeley combinatorics seminar |
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DATE |
SPEAKER |
TITLE (click to show abstract) |

January 30th | Max Wimberley, UC Berkeley |
## Introduction to the Schiffmann Algebra and its ApplicationsDiscovered by Schiffmann and Vasserot in 2008 as the Hall Algebra of an elliptic curve, the Schiffmann algebra has proven to be a remarkably useful tool in unifying and generalizing many topics in symmetric function theory, including the diagonal harmonics and the shuffle conjecture. My talk will focus on providing an accessible exposition of the algebra, its presentations and its symmetries, grounded in computation. As time allows, I will discuss my own investigation into a particular Poisson degeneration of the algebra and its relationship to a conjectured formula for the "triagonal harmonics," the version of the diagonal harmonics with three alphabets of variables instead of two. |

February 6th | Tamsen McGinley, Santa Clara University |
## Crystals Graphs, Perforated Tableaux, and Combinatorial ObjectsCrystal graphs of biwords are directed graphs whose nodes are biwords and whose edges are determined by "crystal operators". These are used to model irreducible representations of GL_n . We present a new model for the nodes of a crystal graph, called a "perforated tableaux", on which the crystal operators are easily defined. We show that several well-known combinatorial objects, including semi-standard Young tableaux, Littlewood-Richardson fillings, and the Robinson-Schensted-Knuth correspondence, naturally appear in the setting of perforated tableaux. |

Friday, February 10th, Evans 740, 4 PM |
Sarah Brauner, University of Minnesota |
## Configuration spaces and combinatorial algebrasIn this talk, I will discuss connections between configuration spaces, an important class of topological space, and combinatorial algebras arising from the theory of reflection groups. In particular, I will present work relating the cohomology rings of some classical configuration spaces—such as the space of n ordered points in Euclidean space—with Solomon’s descent algebra and the peak algebra. The talk will be centered around two questions. First, how are these objects related? Second, how can studying one inform the other? This is joint, on-going work with Marcelo Aguiar and Vic Reiner. |

February 13th | No Seminar | |

February 20th | Academic Holiday - No Seminar | |

February 27th | ||

March 6th | ||

Tuesday March 7th, Evans 748, 4 PM |
Bruce Sagan, Michigan State University | |

March 13th | Ray Li, UC Berkeley | |

March 20th | Lucy Martinez, Rutgers University | |

March 27th | Spring Break - No Seminar | |

April 3rd | Yan Zhuang, Davidson College | |

April 10th | Joseph Pappe, UC Davis | |

April 17th | Dustin Ross, SFSU | |

April 24th | Mark Haiman, UC Berkeley | |

May 1st | Anastasia Chavez, St. Mary's College of CA | |

May 3rd, time and place TBA |
Matt Hogancamp, Northeastern University |